Š. Kment, K. Sivula, A. Naldoni, S. Sarmah, H. Kmentová, M. Kulkarni, Y. Rambabu, P. Schmuki and R. Zbořil, "FeO-based nanostructures and nanohybrids for photoelectrochemical water splitting," PROGRESS IN MATERIALS SCIENCE, vol. 110, p. 100632, 2020.
DOI: 10.1016/j.pmatsci.2019.100632, IF = 39.58
Abstract: The need to satisfy the growing global population’s enormous energy demands is a major challenge for modern societies. Photoelectrochemical (PEC) water splitting (WS) is seen as a leading strategy for producing an extremely promising renewable store of energy – hydrogen (H2). However, PEC-WS is a complex process involving several sequential physicochemical reaction steps including light absorption, separation of photoexcited charges, and surface redox reactions. At present, FeO-based semiconductors represent a unique class of materials known to exhibit very high performance in all these processes. This review summarizes and critically discusses the major components of PEC-WS systems incorporating FeO-based light-harvesting systems, and outlines the progress that has been made, particularly over the last decade. Emphasis is placed on materials used as photoanodes (including hematite and nonhematite iron oxides, spinel iron ferrites, and pseudobrookite iron titanates) as well as materials used as cocatalysts and passivation layers – notably iron hydroxyoxides and their composites. We discuss strategies for overcoming the main limitations of the aforementioned materials via nanostructuring, elemental doping, surface decoration, and the formation of advanced hybrid nanoarchitectures. Finally, we use this knowledge to present a critical overview of the field and the future prospects of Fe-O semiconductors in PEC-WS applications.
B. Cirera, A. Sánchez-Grande, B. de la Torre, J. Santos, S. Edalatmanesh, E. Rodríguez-Sánchez, K. Lauwaet, B. Mallada, R. Zbořil, R. Miranda, O. Gröning, P. Jelínek, N. Martín and D. Ecija, "Tailoring topological order and π-conjugation to engineer quasi-metallic polymers," NATURE NANOTECHNOLOGY, vol. 15, iss. 6, pp. 437-443, 2020.
DOI: 10.1038/s41565-020-0668-7, IF = 39.213
Abstract: Topological band theory predicts that a topological electronic phase transition between two insulators must proceed via closure of the electronic gap. Here, we use this transition to circumvent the instability of metallic phases in π-conjugated one-dimensional (1D) polymers. By means of density functional theory, tight-binding and GW calculations, we predict polymers near the topological transition from a trivial to a non-trivial quantum phase. We then use on-surface synthesis with custom-designed precursors to make polymers consisting of 1D linearly bridged acene moieties, which feature narrow bandgaps and in-gap zero-energy edge states when in the topologically non-trivial phase close to the topological transition point. We also reveal the fundamental connection between topological classes and resonant forms of 1D π-conjugated polymers.
M. Malaki and R. S. Varma, "Mechanotribological Aspects of MXene‐Reinforced Nanocomposites," ADVANCED MATERIALS, vol. 32, iss. 38, pp. 2003154, 2020.
DOI: 10.1002/adma.202003154, IF = 30.849
Abstract: MXenes are recently discovered 2D nanomaterial with superior mechanical, thermal, and tribological properties, being commonly employed in a wide variety of critical research areas, ranging from cancer therapy to energy and environmental applications. Due to their special properties, such as mechanoceramic nature with excellent mechanical performance, thermal stability and rich surface properties, MXenes have tremendous potential as advanced composite structures, especially those based on polymers due to a great affinity between macromolecules and the terminating groups of 2D MXenes. MXenes have been extensively explored in metal matrix nanocomposites as well as in solid‐ or liquid‐based lubrication systems owing to the 2D structure and antifriction characteristics. The purpose of the this paper is to provide a comprehensive insight into the material, mechanical, and tribological properties of the MXene nanolayers with discussions on the recent advancements attained from MXene‐reinforced nanocomposites starting with the synthesis, fabrication techniques, intricacies of the underlying physics and mechanisms, and finally focusing on the progress in computational studies. This analysis of MXene‐based composites will stimulate an emerging field with innumerable opportunities and ample potentials to produce newfangled materials and structures with targeted properties.
S. Hejazi, S. Mohajernia, B. Osuagwu, G. Zoppellaro, P. Andryskova, O. Tomanec, S. Kment, R. Zbořil and P. Schmuki, "On the Controlled Loading of Single Platinum Atoms as a Co‐Catalyst on TiO2 Anatase for Optimized Photocatalytic H2 Generation", ADVANCED MATERIALS, vol. 32, iss. 16, p. 1908505, 2020.
DOI: 10.1002/adma.201908505, IF = 30.849
Abstract: Single‐atom (SA) catalysis is a novel frontline in the catalysis field due to the often drastically enhanced specific activity and selectivity of many catalytic reactions. Here, an atomic‐scale defect engineering approach to form and control traps for platinum SA sites as co‐catalyst for photocatalytic H2 generation is described. Thin sputtered TiO2 layers are used as a model photocatalyst, and compared to the more frequently used (001) anatase sheets. To form stable SA platinum, the TiO2 layers are reduced in Ar/H2 under different conditions (leading to different but defined Ti3+‐Ov surface defects), followed by immersion in a dilute hexachloroplatinic acid solution. HAADF‐STEM results show that only on the thin‐film substrate can the density of SA sites be successfully controlled by the degree of reduction by annealing. An optimized SA‐Pt decoration can enhance the normalized photocatalytic activity of a TiO2 sputtered sample by 150 times in comparison to a conventional platinum‐nanoparticle‐decorated TiO2 surface. HAADF‐STEM, XPS, and EPR investigation jointly confirm the atomic nature of the decorated Pt on TiO2. Importantly, the density of the relevant surface exposed defect centers—thus the density of Pt‐SA sites, which play the key role in photocatalytic activity—can be precisely optimized.
H. L. Chia, C. C. Mayorga‐Martinez, Z. Sofer, P. Lazar, R. D. Webster and M. Pumera, "Vanadium Dopants: A Boon or a Bane for Molybdenum Dichalcogenides‐Based Electrocatalysis Applications," ADVANCED FUNCTIONAL MATERIALS, Article in press, 2020.
DOI: 10.1002/adfm.202009083, IF = 18.808
Abstract: The ever‐rising concerns with regards to energy shortages and climate change have made the search for clean and renewable energy sources a pressing priority for the sustainable development of societies. Although, conventional precious metal‐based catalysts such as platinum, iridium, and ruthenium are able to efficiently catalyze the conversion of chemical to electrical energy, they are often very costly, scarce, and suffer from poor stability, hence impeding their widespread applications. The limitations of the current state‐of art catalysts have propelled tremendous efforts in search for alternative catalysts. Notably, transition metal dichalcogenides (TMDs) have spurred much enthusiasm because of their natural abundance, low cost, and remarkable catalytic activity. Numerous studies have recounted that doping can tune the properties of TMDs and that vanadium dopants reportedly improve the electrical properties of Group 6 TMDs. Herein, the authors aspire to investigate the effects of doping varying amounts of vanadium on molybdenum dichalcogenides on their electrocatalytic activities toward hydrogen evolution reaction, oxygen evolution reaction, and oxygen reduction reaction. Despite previous studies bespeaking promising effects, the results here demonstrate both improvements and worsening of electrocatalytic performances from varying the stoichiometry of vanadium dopants in molybdenum dichalcogenides, depending on the type of materials and intended electrochemical applications.
V. M. Santhini, O. Stetsovych, M. Ondráček, J. I. Mendieta Moreno, P. Mutombo, B. Torre, M. Švec, J. Klívar, I. G. Stará, H. Vázquez, I. Starý and P. Jelínek, "On‐Surface Synthesis of Polyferrocenylene and its Single‐Chain Conformational and Electrical Transport Properties," ADVANCED FUNCTIONAL MATERIALS, Article in press, 2020.
DOI: 10.1002/adfm.202006391, IF = 18.808
Abstract: Unlike intrinsically conductive organic polymers, which are central to organic electronics/photovoltaics, metallopolymers contain multiple redox‐active centers allowing extra control of their intriguing properties. Ferrocene polymers are particularly attractive in this regard, but research of the iconic poly(1,1′‐ferrocenylene), a main‐chain ferrocene polymer with the most densely bound redox‐active iron centers, has practically stopped because it is an insoluble and rather inhomogeneous material. Herein, its synthesis on the Ag(111) surface is reported, based on the Ullmann coupling of 1′,1″′‐diiodo‐1,1″‐biferrocene. Conformationally flexible single‐chain nanowires up to 50 nm in length, thus overcoming the limits of conventional solution polymerization, are characterized by scanning probe microscopy techniques achieving atomic resolution. Single‐chain electrical conductivity measurements are performed in the longitudinal directions revealing apparent metal‐to‐semiconductor transition (depending on the number of ferrocene units lifted from the surface). A simple transport model is established to rationalize this observation.
T. M. Lima, V. de Macedo, D. S. Silva, W. N. Castelblanco, C. A. Pereira, R. E. Roncolatto, M. B. Gawande, R. Zbořil, R. S. Varma and E. A. Urquieta-González, "Molybdenum-promoted cobalt supported on SBA-15: Steam and sulfur dioxide stable catalyst for CO oxidation," APPLIED CATALYSIS B: ENVIRONMENTAL, vol. 277, pp. 119248, 2020.
DOI: 10.1016/j.apcatb.2020.119248, IF = 19.503
Abstract: It was studied a benign one-pot synthesis of a steam and SO2 stable molybdenum promoted cobalt catalyst supported on SBA-15 for CO oxidation runs at 730 ̊C. The physicochemical properties of the catalyst were analyzed by XRD, SEM/HRTEM, UV–vis, Raman spectroscopy, XPS, H2-TPR, and NH3-TPD. Well-dispersed Co3O4 and, molybdenum species allowed to maintain CO conversion close to 90 % against 55 % over the non-Mo-promoted Co-catalyst. That promising behavior was attributed to the strong Co-Mo interaction that improved the acidic properties, which strongly decreased deactivation by SO2 and water steam. The impregnated catalyst presented formation of aggregated MoO3 species and Co3O4 mainly inside the SBA-15 mesopores, leading to lower CO oxidation activity and lower catalytic stability in the presence of the above interfering compounds. Thus, the one-pot prepared molybdenum promoted cobalt catalyst supported over mesoporous silica SBA-15 emerges as a potential alternative to substitute CO oxidation catalysts based on noble metals.
P. Procházka, M. A. Gosalvez, L. Kormoš, B. de la Torre, A. Gallardo, J. Alberdi-Rodriguez, T. Chutora, A. O. Makoveev, A. Shahsavar, A. Arnau, P. Jelínek and J. Čechal, "Multiscale Analysis of Phase Transformations in Self-Assembled Layers of 4,4′-Biphenyl Dicarboxylic Acid on the Ag(001) Surface," ACS NANO, vol. 14, iss. 6, pp. 7269-7279, 2020.
DOI: 10.1021/acsnano.0c02491, IF = 15.881
Abstract: Understanding the nucleation and growth kinetics of thin films is a prerequisite for their large-scale utilization in devices. For self-assembled molecular phases near thermodynamic equilibrium the nucleation–growth kinetic models are still not developed. Here, we employ real-time low-energy electron microscopy (LEEM) to visualize a phase transformation induced by the carboxylation of 4,4′-biphenyl dicarboxylic acid on Ag(001) under ultra-high-vacuum conditions. The initial (α) and transformed (β) molecular phases are characterized in detail by X-ray photoemission spectroscopy, single-domain low-energy electron diffraction, room-temperature scanning tunneling microscopy, noncontact atomic force microscopy, and density functional theory calculations. The phase transformation is shown to exhibit a rich variety of phenomena, including Ostwald ripening of the α domains, burst nucleation of the β domains outside the α phase, remote dissolution of the α domains by nearby β domains, and a structural change from disorder to order. We show that all phenomena are well described by a general growth–conversion–growth (GCG) model. Here, the two-dimensional gas of admolecules has a dual role: it mediates mass transport between the molecular islands and hosts a slow deprotonation reaction. Further, we conclude that burst nucleation is consistent with a combination of rather weak intermolecular bonding and the onset of an additional weak many-body attractive interaction when a molecule is surrounded by its nearest neighbors. In addition, we conclude that Ostwald ripening and remote dissolution are essentially the same phenomenon, where a more stable structure grows at the expense of a kinetically formed, less stable entity via transport through the 2D gas. The proposed GCG model is validated through kinetic Monte Carlo (kMC) simulations.
M. K. Albolkany, Y. Wang, W. Li, S. Arooj, C. Chen, N. Wu, Y. Wang, R. Zbořil, R. A. Fischer and B. Liu, "Dual‐Function HKUST‐1: Templating and Catalyzing Formation of Graphitic Carbon Nitride Quantum Dots Under Mild Conditions," ANGEWANDTE CHEMIE INTERNATIONAL EDITION, Article in press. 2020.
DOI: 10.1002/anie.202009710, IF = 15.336
Abstract: Graphitic carbon nitride quantum dots (g‐CNQDs) are highly promising photoresponsive materials. However, synthesis of monodispersed g‐CNQDs remains challenging. Here we report the dual function of MOF [Cu3BTC2] (HKUST‐1) as a catalyst and template simultaneously to prepare g‐CNQDs under mild conditions. Cyanamide (CA), a graphitic carbon nitride precursor, catalytically dimerized inside the larger MOF cavities at 90 °C and condensed into g‐CNQDs at 120 °C in a controlled fashion. The HKUST‐1 template was stable under the reaction conditions, leading to uniform g‐CNQDs with a particle size of 2.22±0.68 nm. The as prepared g‐CNQDs showed photoluminescence emission with a quantum yield of 3.1 %. This concept (MOF dual functionality) for catalyzing CA polycondensation (open metal sites (OMSs) effect) and controlling the produced particle size (pore‐templating effect), together with the tunable MOF porosity, is expected to produce unique g‐CNQDs with controllable size, morphology, and surface functionality.
M. Lamanec, R. Lo, D. Nachtigallová, A. Bakandritsos, E. Mohammadi, M. Dračínský, R. Zbořil, P. Hobza and W. Wang, "The Existence of a N→C Dative Bond in the C
60
–Piperidine Complex," ANGEWANDTE CHEMIE INTERNATIONAL EDITION, Article in press, 2020.
DOI: 10.1002/anie.202012851, IF = 15.336
Abstract: The complexes formed between carbon allotropes (C20, C60 fullerenes, graphene, and single‐wall carbon nanotubes) and piperidine have been investigated by means of computational quantum chemical and experimental IR and NMR techniques. Alongside hydrogen bonds, the C⋅⋅⋅N tetrel bond, and lone‐pair⋅⋅⋅π interactions, the unexpected N→C dative/covalent bond has been detected solely in complexes of fullerenes with piperidine. Non‐planarity and five‐member rings of carbon allotropes represent the key structural prerequisites for the unique formation of a dative N→C bond. The results of thermodynamics calculations, molecular dynamics simulations, and NMR and FTIR spectroscopy explain the specific interactions between C60 and piperidine. The differences in behavior of individual carbon allotropes in terms of dative bonding formation brings a new insight into their controllable organic functionalization.
V. M. Santhini, C. Wäckerlin, A. Cahlík, M. Ondráček, S. Pascal, A. Matěj, O. Stetsovych, P. Mutombo, P. Lazar, O. Siri and P. Jelínek, "1D Coordination π–d Conjugated Polymers with Distinct Structures Defined by the Choice of the Transition Metal: Towards a New Class of Antiaromatic Macrocycles," ANGEWANDTE CHEMIE INTERNATIONAL EDITION, vol. 60, iss. 1, pp. 439-445, 2020.
DOI: 10.1002/anie.202011462, IF = 15.336
Abstract: Recently π–d conjugated coordination polymers have received a lot of attention owing to their unique material properties, although synthesis of long and defect‐free polymers remains challenging. Herein we introduce a novel on‐surface synthesis of coordination polymers with quinoidal ligands under ultra‐high vacuum conditions, which enables formation of flexible coordination polymers with lengths up to hundreds of nanometers. Moreover, this procedure allows the incorporation of different transition‐metal atoms with four‐ or two‐fold coordination. Remarkably, the two‐fold coordination mode revealed the formation of wires constituted by (electronically) independent 12‐membered antiaromatic macrocycles linked together through two C−C single bonds.
A. Sánchez‐Grande, J. I. Urgel, A. Cahlík, J. Santos, S. Edalatmanesh, E. Rodríguez‐Sánchez, K. Lauwaet, P. Mutombo, D. Nachtigallová, R. Nieman, H. Lischka, B. Torre, R. Miranda, O. Gröning, N. Martín, P. Jelínek and D. Écija, "Diradical Organic One‐Dimensional Polymers Synthesized on a Metallic Surface," ANGEWANDTE CHEMIE INTERNATIONAL EDITION, vol. 59, iss. 40, pp. 17594-17599, 2020.
DOI: 10.1002/anie.202006276, IF = 15.336
Abstract: We report on the synthesis and characterization of atomically precise one‐dimensional diradical peripentacene polymers on a Au(111) surface. By means of high‐resolution scanning probe microscopy complemented by theoretical simulations, we provide evidence of their magnetic properties, which arise from the presence of two unpaired spins at their termini. Additionally, we probe a transition of their magnetic properties related to the length of the polymer. Peripentacene dimers exhibit an antiferromagnetic (S=0) singlet ground state. They are characterized by singlet–triplet spin‐flip inelastic excitations with an effective exchange coupling (Jeff) of 2.5 meV, whereas trimers and longer peripentacene polymers reveal a paramagnetic nature and feature Kondo fingerprints at each terminus due to the unpaired spin. Our work provides access to the precise fabrication of polymers featuring diradical character which are potentially useful in carbon‐based optoelectronics and spintronics.
H. Kruse, K. Mrazikova, L. D'Ascenzo, J. Sponer and P. Auffinger, "Short but Weak: The Z‐DNA Lone‐Pair⋅⋅⋅π Conundrum Challenges Standard Carbon Van der Waals Radii," ANGEWANDTE CHEMIE INTERNATIONAL EDITION, vol. 59, iss. 38, pp. 16553-16560, 2020.
DOI: 10.1002/anie.202004201, IF = 15.336
Abstract: Current interest in lone‐pair⋅⋅⋅π (lp⋅⋅⋅π) interactions is gaining momentum in biochemistry and (supramolecular) chemistry. However, the physicochemical origin of the exceptionally short (ca. 2.8 Å) oxygen‐to‐nucleobase plane distances observed in prototypical Z‐DNA CpG steps remains unclear. High‐level quantum mechanical calculations, including SAPT2+3 interaction energy decompositions, demonstrate that lp⋅⋅⋅π contacts do not result from n→π* orbital overlaps but from weak dispersion and electrostatic interactions combined with stereochemical effects imposed by the locally strained structural context. They also suggest that the carbon van der Waals (vdW) radii, originally derived for sp3 carbons, should not be used for smaller sp2 carbons attached to electron‐withdrawing groups. Using a more adapted carbon vdW radius results in these lp⋅⋅⋅π contacts being no longer of the sub‐vdW type. These findings challenge the whole lp⋅⋅⋅π concept that refers to elusive orbital interactions that fail to explain short interatomic contact distances.
K. Holá, M. V. Pavliuk, B. Németh, P. Huang, L. Zdražil, H. Land, G. Berggren and H. Tian, "Carbon Dots and [FeFe] Hydrogenase Biohybrid Assemblies for Efficient Light-Driven Hydrogen Evolution," ACS CATALYSIS, vol. 10, iss. 17, pp. 9943-9952, 2020.
DOI: 10.1021/acscatal.0c02474, IF = 13.084
Abstract: Artificial photosynthesis is seen as a path to convert and store solar energy into chemical energy for our society. In this work, highly fluorescent aspartic acid-based carbon dots (CDs) are synthesized and employed as a photosensitizer to drive photocatalytic hydrogen evolution with an [FeFe] hydrogenase (CrHydA1). The direct interaction in CDs from l-aspartic acid (AspCDs)/CrHydA1 self-assembly systems, which is visualized from native gel electrophoresis, has been systematically investigated to understand the electron-transfer dynamics and its impact on photocatalytic efficiency. The study discloses the significant influence of the electrostatic surrounding generated by sacrificial electron donors on the intimate interplay within the oppositely charged subunits of the biohybrid assembly as well as the overall photocatalytic performance. The system reaches an external quantum efficiency of 1.7% at 420 nm and an initial activity of 1.73 μmol(H2) mg–1(hydrogenase) min–1 under favorable electrostatic conditions. Owing to the ability of the synthesized AspCDs to operate efficiently under visible light, in contrast to other materials that require UV illumination, the stability of the biohybrid assembly in the presence of a redox mediator extends beyond 1 week.
F. Malara, M. Fracchia, H. Kmentová, R. Psaro, A. Vertova, D. Oliveira de Souza, G. Aquilanti, L. Olivi, P. Ghigna, A. Minguzzi and A. Naldoni, "Direct Observation of Photoinduced Higher Oxidation States at a Semiconductor/Electrocatalyst Junction," ACS CATALYSIS, vol. 10, iss. 18, pp. 10476-10487, 2020.
DOI: 10.1021/acscatal.0c02789, IF = 13.084
Abstract: >Photoelectrochemical (PEC) water splitting devices using semiconductors and electrocatalysts rely on heterogeneous interfaces that drive charge separation, thus determining potential gradients that dictate the reaction efficiency. The PEC potential of the electrocatalyst depends on the chemical oxidation state of forming elements, which may strongly vary under the photoinduced charge flow. However, element-sensitive, real-time measurements of the oxidation state of the electrocatalyst are not generally possible by using conventional X-ray absorption techniques. Here we show that fixed energy X-ray absorption voltammetry and chronoamperometry, which measures the X-ray absorption coefficient variations along with photocurrent, can follow in real time the redox kinetics of electrocatalysts in operando. In order to demonstrate the validity, we investigate hematite (α-Fe2O3) photoanodes covered with a nickel hydroxide electrocatalyst and show that it is fully oxidized by photogenerated holes to nickel oxyhydroxide with Ni reaching higher oxidation state (NiIV) than that observed under electrocatalytic oxygen evolution in dark conditions. Highly oxidized Ni results from charge accumulation in the overlayer and can be observed only in the case of thick layers (with low PEC performance). On the other hand, the average oxidation state of Ni reaches lower values, under operative conditions, for very thin layers resulting in high PEC activity. We complete our study by presenting PEC activity and impedance spectroscopy analysis using different thickness of electrocatalyst, thus proving a detailed picture of the multiple and complex charge transfer processes occurring at a semiconductor/electrocatalyst junction.
D. Spanu, A. Minguzzi, S. Recchia, F. Shahvardanfard, O. Tomanec, R. Zboril, P. Schmuki, P. Ghigna and M. Altomare, "An Operando X-ray Absorption Spectroscopy Study of a NiCu−TiO2 Photocatalyst for H2 Evolution," ACS CATALYSIS, vol. 10, iss. 15, pp. 8293-8302, 2020.
DOI: 10.1021/acscatal.0c01373, IF = 13.084
Abstract: Cu- or Ni-decorated semiconductors represent a potential low-cost alternative to noble-metal-modified photocatalysts. Even more effective are bimetallic NiCu nanoparticles, which can provide a remarkable photocatalytic H2 evolution enhancement compared to single-element Cu or Ni systems. The main concern of such alloyed co-catalysts is their activity with respect to alteration of their elemental composition and oxidation state over reaction time. Ex situ characterization techniques provide controversial interpretations of the co-catalytic role of the individual elements. Hypotheses such as the in situ reduction of “native” Ni or Cu species during photocatalysis, the oxidation of metallic Cu or Ni into oxides or hydroxides, or the formation of p–n junctions or core/shell structures have been proposed. Herein, we present an operando X-ray absorption spectroscopy study of a NiCu–TiO2 system under UV light illumination in ethanol–water solutions, i.e., under photocatalytic H2 evolution conditions. The experimental approach allows for monitoring in real time chemical changes that take place in the co-catalyst under intermittent illumination, i.e., under light on–off cycles. We show that while Ni and Cu are partially oxidized in the as-formed NiCu co-catalyst (air-formed surface oxides or hydroxides) and undergo partial dissolution in the liquid phase under dark conditions, such Ni and Cu oxidized and dissolved species are reduced/redeposited as a bimetallic NiCu phase at the TiO2 surface under illumination. The dissolution/redeposition mechanism is triggered by TiO2 conduction band electrons. We not only prove a UV-light-induced healing of the NiCu co-catalyst but also unambiguously demonstrate that the species responsible for the strongly enhanced photocatalytic H2 evolution of NiCu nanoparticles are the metallic states of Ni and Cu.
S. Rej, L. Mascaretti, E. Y. Santiago, O. Tomanec, S. Kment, Z. Wang, R. Zbořil, P. Fornasiero, A. O. Govorov and A. Naldoni, "Determining Plasmonic Hot Electrons and Photohermal Effects during H2 Evolution with TiN–Pt Nanohybrids," ACS CATALYSIS, vol. 10, iss. 9, pp. 5261–5271, 2020.
DOI: 10.1021/acscatal.0c00343, IF = 13.084
Abstract: Hydrogen storage in chemical compounds is a promising strategy to enable lightweight, high density, and safe hydrogen technologies. However, the hydrogen release rate from these chemicals is limited by the intrinsic catalytic activity of metal catalysts, which can be enhanced by using light irradiation. Here nanohybrids including a core of plasmonic TiN and multiple Pt nanocrystal catalytic centers are assembled and show, under resonant conditions at 700 nm, hot electrons driven hydrogen evolution from ammonia borane at an apparent quantum yield of 120%. It is also demonstrated that solar irradiation enhances the activity of TiN-Pt nanohybrids by one order of magnitude through two synergistic mechanisms: the hot electrons and collective-heating contributions. Using the microscopic calculation of the photoinduced temperature around a single nanocrystal, it is revealed that the collective plasmonic heating regime dominates the macroscopic temperature distribution in the system. The presented data show that plasmonic hot electrons and photothermal heating can be used in synergy to trigger hydrogen release from ammonia borane on demand, providing a general strategy for greatly enhancing the activity in the dark of metal catalysts.
M. B. Gawande, P. Fornasiero and R. Zbořil, "Carbon-Based Single-Atom Catalysts for Advanced Applications," ACS CATALYSIS, vol. 10, iss. 3, pp. 2231-2259, 2020.
DOI: 10.1021/acscatal.9b04217, IF = 13.084
Abstract: Carbon-based materials are widely employed as metal-free catalysts or supports in catalysis, energy, and ecological applications because of their interesting properties. Generally, their high surface areas, size, shape, porosity, and the possibility of incorporating additional moieties through chemical functional designs are believed to be essential for enriching the catalytic activity of carbon-containing materials. Lately, the new field of single-atom catalysts (SACs) has emerged as the finest alternative for not only homogeneous but also heterogeneous catalysts used in various kinds of catalytic applications. Among a variety of SACs, carbon-based SACs are widely investigated catalysts because of their extraordinary features such as tunable morphologies, ordered porosity, and effortless immobilization through various metals (noble and non-noble), making them highly efficient single-atom catalysts for numerous important catalytic applications. Herein, we intend to report on the progress achieved in researching carbon-based single-atom catalysts, including primarily metals such as Co, Cu, Zn, Pd, Ni, Pt, among others, embedded in carbon matrices and applied to applications in organic catalysis, photocatalysis, and electrocatalysis. It is important to point out that the main focus of this Review is directed to the activity and applications of single-atom catalysts, which are discussed in detail; thus, characterization and rationalization are excluded. Finally, we provide a future perspective on the development and progress made on a carbon-based single metal atom for catalysis.
R. K. Sharma, P. Yadav, M. Yadav, R. Gupta, P. Rana, A. Srivastava, R. Zbořil, R. S. Varma, M. Antonietti and M. B. Gawande, "Recent development of covalent organic frameworks (COFs): synthesis and catalytic (organic-electro-photo) applications," MATERIALS HORIZONS, vol. 7, iss. 2, pp. 411-454, 2020.
DOI: 10.1039/c9mh00856j, IF = 13.266
Abstract: Covalent organic frameworks (COFs) are one of the most important and dynamic members of the porous organic materials and are constructed using reticular chemistry with the building blocks being connected via covalent bonds. Due to their fascinating properties such as large surface area; structural versatility; effortless surface modification; and high chemical stability, COFs are being widely deployed in catalytic; sensing; adsorption; gas storage; and many other valuable applications. This review summarizes selected and most recent espoused synthetic methodologies for their assembly including the formation of magnetic COFs. Potential insights in the field of catalysis; electrocatalysis; and photocatalysis, where COFs can serve as excellent platforms for supporting catalytic species, are also illustrated.
K. Kubiasová, J. C. Montesinos, O. Šamajová, J. Nisler, V. Mik, H. Semerádová, L. Plíhalová, O. Novák, P. Marhavý, N. Cavallari, D. Zalabák, K. Berka, K. Doležal, P. Galuszka, J. Šamaj, M. Strnad, E. Benková, O. Plíhal and L. Spíchal, "Cytokinin fluoroprobe reveals multiple sites of cytokinin perception at plasma membrane and endoplasmic reticulum," NATURE COMMUNICATIONS, vol. 11, iss. 1, pp. 4285, 2020.
DOI: 10.1038/s41467-020-17949-0, IF = 14.919
Abstract: Plant hormone cytokinins are perceived by a subfamily of sensor histidine kinases (HKs), which via a two-component phosphorelay cascade activate transcriptional responses in the nucleus. Subcellular localization of the receptors proposed the endoplasmic reticulum (ER) membrane as a principal cytokinin perception site, while study of cytokinin transport pointed to the plasma membrane (PM)-mediated cytokinin signalling. Here, by detailed monitoring of subcellular localizations of the fluorescently labelled natural cytokinin probe and the receptor ARABIDOPSIS HISTIDINE KINASE 4 (CRE1/AHK4) fused to GFP reporter, we show that pools of the ER-located cytokinin receptors can enter the secretory pathway and reach the PM in cells of the root apical meristem, and the cell plate of dividing meristematic cells. Brefeldin A (BFA) experiments revealed vesicular recycling of the receptor and its accumulation in BFA compartments. We provide a revised view on cytokinin signalling and the possibility of multiple sites of perception at PM and ER.
J. Berger, M. Ondráček, O. Stetsovych, P. Malý, P. Holý, J. Rybáček, M. Švec, I. G. Stará, T. Mančal, I. Starý and P. Jelínek, "Quantum dissipation driven by electron transfer within a single molecule investigated with atomic force microscopy," NATURE COMMUNICATIONS, vol. 11, iss. 1, p. 1337, 2020.
DOI: 10.1038/s41467-020-15054-w, IF = 14.919
Abstract: Intramolecular charge transfer processes play an important role in many biological, chemical and physical processes including photosynthesis, redox chemical reactions and electron transfer in molecular electronics. These charge transfer processes are frequently influenced by the dynamics of their molecular or atomic environments, and they are accompanied with energy dissipation into this environment. The detailed understanding of such processes is fundamental for their control and possible exploitation in future technological applications. Most of the experimental studies of the intramolecular charge transfer processes so far have been carried out using time-resolved optical spectroscopies on large molecular ensembles. This hampers detailed understanding of the charge transfer on the single molecular level. Here we build upon the recent progress in scanning probe microscopy, and demonstrate the control of mixed valence state. We report observation of single electron transfer between two ferrocene redox centers within a single molecule and the detection of energy dissipation associated with the single electron transfer.
T. Raček, O. Schindler, D. Toušek, V. Horský, K. Berka, J. Koča and R. Svobodová, "Atomic Charge Calculator II: web-based tool for the calculation of partial atomic charges," NUCLEIC ACIDS RESEARCH, vol. 48, iss. W1, pp. W591-W596, 2020.
DOI: 10.1093/nar/gkaa367, IF = 16.971
Abstract: Partial atomic charges serve as a simple model for the electrostatic distribution of a molecule that drives its interactions with its surroundings. Since partial atomic charges are frequently used in computational chemistry, chemoinformatics and bioinformatics, many computational approaches for calculating them have been introduced. The most applicable are fast and reasonably accurate empirical charge calculation approaches. Here, we introduce Atomic Charge Calculator II (ACC II), a web application that enables the calculation of partial atomic charges via all the main empirical approaches and for all types of molecules. ACC II implements 17 empirical charge calculation methods, including the highly cited (QEq, EEM), the recently published (EQeq, EQeq+C), and the old but still often used (PEOE). ACC II enables the fast calculation of charges even for large macromolecular structures. The web server also offers charge visualization, courtesy of the powerful LiteMol viewer. The calculation setup of ACC II is very straightforward and enables the quick calculation of high-quality partial charges. The application is available at https://acc2.ncbr.muni.cz.
S. K. Yadav, G. K. Grandhi, D. P. Dubal, J. C. Mello, M. Otyepka, R. Zbořil, R. A. Fischer and K. Jayaramulu, "Metal Halide Perovskite@Metal‐Organic Framework Hybrids: Synthesis, Design, Properties, and Applications," SMALL, vol. 16, iss. 47, pp. 2004891, 2020.
DOI: 10.1002/smll.202004891, IF = 13.281
Abstract: Metal halide perovskites (MHPs) have excellent optoelectronic and photovoltaic applications because of their cost‐effectiveness, tunable emission, high photoluminescence quantum yields, and excellent charge carrier properties. However, the potential applications of the entire MHP family are facing a major challenge arising from its weak resistance to moisture, polar solvents, temperature, and light exposure. A viable strategy to enhance the stability of MHPs could lie in their incorporation into a porous template. Metal‐organic frameworks (MOFs) have outstanding properties, with a unique network of ordered/functional pores, which render them promising for functioning as such a template, accommodating a wide range of MHPs to the nanosized region, alongside minimizing particle aggregation and enhancing the stability of the entrapped species. This review highlights recent advances in design strategies, synthesis, characterization, and properties of various hybrids of MOFs with MHPs. Particular attention is paid to a critical review of the emergence of MHP@MOF for comprehensive studies of next‐generation materials for various technological applications including sensors, photocatalysis, encryption/decryption, light‐emitting diodes, and solar cells. Finally, by summarizing the state‐of‐the‐art, some promising future applications of reported hybrids are proposed. Considering the inherent correlation and synergic functionalities of MHPs and MOFs, further advancement; new functional materials; and applications can be achieved through designing MHP@MOF hybrids.
S. S. Lam, V. Nguyen, M. T. Nguyen Dinh, D. Q. Khieu, D. D. La, H. T. Nguyen, D. V. N. Vo, C. Xia, R. S. Varma, M. Shokouhimehr, C. C. Nguyen, Q. V. Le and W. Peng, "Mainstream avenues for boosting graphitic carbon nitride efficiency: towards enhanced solar light-driven photocatalytic hydrogen production and environmental remediation," JOURNAL OF MATERIALS CHEMISTRY A, vol. 8, iss. 21, pp. 10571-10603, 2020.
DOI: 10.1039/d0ta02582h, IF = 12.732
Abstract: Photocatalysts comprising 2D carbon nitride-based systems have emerged as a fervently researched topic for addressing the problems of fuel depletion and the environment. However, the photocatalytic activities of pristine g-C3N4 are still mediocre and suffer from issues pertaining to the restrictions in light absorption, charge separation, and carrier-induced surface reactions; however, efforts have been made in the past decades to boost the efficiencies. This review endeavors to present a roadmap to prepare high-performance g-C3N4 photocatalysts by expounding the cutting-edge research on g-C3N4 materials either as a single component or g-C3N4-based composites including current challenges and perspectives on this topical theme. We believe that this review will provide a broader picture and recommendations for the preparation of superior g-C3N4 photocatalysts towards a greener, cleaner, and resilient future.
Y. Makimizu, J. Yoo, M. Poornajar, N. T. Nguyen, H. Ahn, I. Hwang, S. Kment and P. Schmuki, "Effects of low oxygen annealing on the photoelectrochemical water splitting properties of α-Fe2O3," JOURNAL OF MATERIALS CHEMISTRY A, vol. 8, iss. 3, pp. 1315-1325, 2020.
DOI: 10.1039/c9ta10358a, IF = 12.732
Abstract: Photoelectrochemical (PEC) water splitting is a promising method for converting solar energy into chemical energy stored in the form of hydrogen. Nanostructured hematite (α-Fe2O3) is one of the most attractive materials for highly efficient charge carrier generation and collection, due to its large specific surface area and shortened minority carrier diffusion length required to reach the surface. In the present work, PEC water splitting performance of α-Fe2O3 prepared by anodization of thin iron layers on FTO glass and subsequent annealing in a low O2–Ar atmosphere with only 0.03% O2 was investigated. The key finding is that annealing anodic nanostructures with a low oxygen concentration provides a strongly enhanced PEC performance compared with classical air annealing. The photocurrent of the former at 1.5 V vs. RHE results in 1.1 mA cm−2, being 11 times higher than that of the latter. The enhancement of the PEC performance of α-Fe2O3 annealed in a low oxygen atmosphere can be attributed to the controlled morphology, Sn doping, and introduction of oxygen vacancies, which contribute to the enhancement of the hole flux from the photogenerated site to the reactive surface and additionally lead to an enhanced hole transfer at the interface between α-Fe2O3 and the electrolyte. From the obtained results, it is evident that low oxygen annealing is a surprisingly effective method of defect engineering and optimizing α-Fe2O3 electrodes for a maximized PEC water splitting performance.
S. Mohajernia, P. Andryskova, G. Zoppellaro, S. Hejazi, S. Kment, R. Zboril, J. Schmidt and P. Schmuki, "Influence of Ti3+ defect-type on heterogeneous photocatalytic H2 evolution activity of TiO2," JOURNAL OF MATERIALS CHEMISTRY A, vol. 8, iss. 3, pp. 1432-1442, 2020.
DOI: 10.1039/c9ta10855f, IF = 12.732
Abstract: Reduced titanium dioxide has recently attracted large attention, particularly for its unique co-catalyst-free heterogeneous photocatalytic application for H2 generation. The enhanced photocatalytic activity of the reduced TiO2 was previously ascribed to the introduction of point crystal defects (mainly Ti3+ centers), which result in the formation of intrinsic co-catalytic centers and enhanced visible light absorption. In this work, we systematically investigate the effect of different defects in the TiO2−x lattice on photocatalytic H2 evolution. To introduce different types of defects, thermal annealing in air (oxidative), Ar (inert), Ar/H2 (reducing), and H2 (reducing) atmospheres was performed on commercially available anatase nanopowder. Then, the powders were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) to clarify the effect of treatment on material properties. Furthermore, the defect types were characterized by electron paramagnetic resonance (EPR) spectroscopy. We show that thermal annealing in different atmospheres can form different amounts of different defect types in the TiO2 structure. The highest photocatalytic activation is achieved by annealing the anatase powder in a reducing atmosphere for an appropriate temperature/annealing time. By combining the results from H2 generation and EPR analysis we show that the simultaneous presence of two types of defects, i.e. surface exposed Ti3+ and lattice embedded Ti3+ centers in an optimum low concentration is the determining factor for an optimized photocatalytic H2 evolution rate. In fact, annealing anatase powder under the so-reported optimized conditions in reducing atmosphere leads to the generation of a considerable amount of H2, with rates as high as 338 μmol h−1 g−1.
L. Wu, L. Wang, J. Zhu, M. Sun, X. Liu, P. Schmuki and J. Zhang, "Novel highly active and self-healing Co(CO3)xOHy cocatalysts on BiVO4 photoanodes for effective solar water oxidation," JOURNAL OF MATERIALS CHEMISTRY A, vol. 8, iss. 5, pp. 2563-2570, 2020.
DOI: 10.1039/c9ta13122a, IF = 12.732
Abstract: Recent reports show that Co-Pi cocatalysts on some photoanodes, such as Fe2O3 or BiVO4, accelerate the surface water oxidation rate, acting as a hole extracting layer that improves charge separation or as a “surface passivation agent”. In contrast, on semiconductors such as BiVO4, deposition of classic Co-based oxygen evolution catalysts (e.g. Co3O4, CoOOH) leads to a relatively low improvement of the photoelectrochemical (PEC) performance. This illustrates that even though a species may be an excellent electrocatalyst, it may not be an effective co-catalyst for PEC reactions. Clearly, for different semiconductors there is a need to directly identify and prepare specific, highly active and low-cost cocatalysts for promoting PEC water oxidation. Co(CO3)0.5(OH)·0.11H2O (or in general Co(CO3)xOHy) is usually used as a precursor to synthesize a range of Co-based efficient electrocatalysts. Herein, we for the first time show that Co(CO3)xOHy on BiVO4 provides an excellent oxygen evolution reaction activity, even close to the so far most efficient dual-layer FeOOH/NiOOH cocatalysts. Decoration of BiVO4 with Co(CO3)xOHy and the resulting photoanode shows a remarkable enhancement of photocurrent, achieving a photocurrent density of 5.0 mA cm−2 at 1.23 VRHE with an onset potential of 0.3 VRHE, which is one of the highest PEC activities of BiVO4 reported up to now. The outstanding PEC performance can be attributed to the improvement of charge separation and transfer efficiency caused by a uniform thin coating of Co(CO3)xOHy. The Co(CO3)xOHy exhibits the highest density of active sites, the highest surface area, and the best OER activity among the investigated cobalt-based cocatalysts. Remarkably, the Co(CO3)xOHy also displays a self-healing function in borate buffered electrolytes. Therefore, this work not only describes low-cost but highly active cobalt-based catalysts for PEC solar water oxidation, but additionally shows a self-repair function of this system.
A. Naldoni, Z. A. Kudyshev, L. Mascaretti, S. P. Sarmah, S. Rej, J. P. Froning, O. Tomanec, J. E. Yoo, D. Wang, S. Kment, T. Montini, P. Fornasiero, V. M. Shalaev, P. Schmuki, A. Boltasseva and R. Zbořil, "Solar Thermoplasmonic Nanofurnace for High-Temperature Heterogeneous Catalysis," NANO LETTERS, vol. 20, iss. 5, pp. 3663–3672, 2020.
DOI: 10.1021/acs.nanolett.0c00594, IF = 11.189
Abstract: Most of existing solar thermal technologies require highly concentrated solar power to operate in the temperature range 300–600 °C. Here, thin films of refractory plasmonic TiN cylindrical nanocavities manufactured via flexible and scalable process are presented. The fabricated TiN films show polarization-insensitive 95% broadband absorption in the visible and near-infrared spectral ranges and act as plasmonic “nanofurnaces” capable of reaching temperatures above 600 °C under moderately concentrated solar irradiation (~20 Suns). The demonstrated structures can be used to control nanometer-scale chemistry with zeptolitre (10–21 L) volumetric precision, catalyzing C–C bond formation and melting of inorganic deposits. It is further shown the possibility to perform solar thermal CO oxidation at rates of 16 mol h–1 m–2 and with a solar-to-heat thermoplasmonic efficiency of 63%. Access to scalable, cost-effective refractory plasmonic nanofurnaces opens the way to the development of modular solar thermal devices for sustainable catalytic processes.
J. Kopecka, P. Trouillas, A. Č. Gašparović, E. Gazzano, Y. G. Assaraf and C. Riganti, "Phospholipids and cholesterol: Inducers of cancer multidrug resistance and therapeutic targets," DRUG RESISTANCE UPDATES, vol. 49, p. 100670, 2020.
DOI: 10.1016/j.drup.2019.100670, IF = 18.500
Abstract: Lipids, phospholipids and cholesterol in particular, are the predominant components of the plasma membrane, wherein multidrug efflux transporters of the ATP-binding cassette (ABC) superfamily reside as integral pump proteins. In the current review, we discuss how lipids potently modulate the expression and activity of these multidrug efflux pumps, contributing to the development of the multidrug resistance (MDR) phenotype in cancer. The molecular mechanisms underlying this modulation of the MDR phenotype are pleiotropic. First, notwithstanding the high intra-and inter-tumor variability, MDR cells display an altered composition of plasma membrane phospholipids and glycosphingolipids, and are enriched with very long saturated fatty acid chains. This feature, along with the increased levels of cholesterol, decrease membrane fluidity, alter the spatial organization of membrane nano- and micro-domains, interact with transmembrane helices of ABC transporters, hence favoring drug binding and release. Second, MDR cells exhibit a peculiar membrane lipid composition of intracellular organelles including mitochondria and endoplasmic reticulum (ER). In this respect, they contain a lower amount of oxidizable fatty acids, hence being more resistant to oxidative stress and chemotherapy-induced apoptosis. Third, drug resistant cancer cells have a higher ratio of monosatured/polyunsatured fatty acids: this lipid signature reduces the production of reactive aldehydes with cytotoxic and pro-inflammatory activity and, together with the increased activity of anti-oxidant enzymes, limits the cellular damage induced by lipid peroxidation. Finally, specific precursors of phospholipids and cholesterol including ceramides and isoprenoids, are highly produced in MDR cells; by acting as second messengers, they trigger multiple signaling cascades that induce the transcription of drug efflux transporter genes and/or promote a metabolic reprogramming which supports the MDR phenotype.
High-throughput lipidomics and computational biology technologies are a great tool in analyzing the tumor lipid signature in a personalized manner and in identifying novel biomarkers of drug resistance. Moreover, beyond the induction of MDR, lipid metabolism offers a remarkable opportunity to reverse MDR by using lipid analogues and repurposing lipid-targeting drugs (e.g. statins and aminobisphosphonates) that reprogram the lipid composition of drug resistant cells, hence rendering them drug sensitive.
A. Tolios, J. De Las Rivas, E. Hovig, P. Trouillas, A. Scorilas and T. Mohr, "Computational approaches in cancer multidrug resistance research: Identification of potential biomarkers, drug targets and drug-target interactions," DRUG RESISTANCE UPDATES, vol. 48, p. 100662, 2020.
DOI: 10.1016/j.drup.2019.100662, IF = 18.500
Abstract: Like physics in the 19th century, biology and molecular biology in particular, has been fertilized and enhanced like few other scientific fields, by the incorporation of mathematical methods. In the last decades, a whole new scientific field, bioinformatics, has developed with an output of over 30,000 papers a year (Pubmed search using the keyword “bioinformatics”). Huge databases of mass throughput data have been established, with ArrayExpress alone containing more than 2.7 million assays (October 2019). Computational methods have become indispensable tools in molecular biology, particularly in one of the most challenging areas of cancer research, multidrug resistance (MDR). However, confronted with a plethora of different algorithms, approaches, and methods, the average researcher faces key questions: Which methods do exist? Which methods can be used to tackle the aims of a given study? Or, more generally, how do I use computational biology/bioinformatics to bolster my research?
The current review is aimed at providing guidance to existing methods with relevance to MDR research. In particular, we provide an overview on: a) the identification of potential biomarkers using expression data; b) the prediction of treatment response by machine learning methods; c) the employment of network approaches to identify gene/protein regulatory networks and potential key players; d) the identification of drug-target interactions; e) the use of bipartite networks to identify multidrug targets; f) the identification of cellular subpopulations with the MDR phenotype; and, finally, g) the use of molecular modeling methods to guide and enhance drug discovery.
This review shall serve as a guide through some of the basic concepts useful in MDR research. It shall give the reader some ideas about the possibilities in MDR research by using computational tools, and, finally, it shall provide a short overview of relevant literature.
A. Goswami, R. G. Kadam, J. Tuček, Z. Sofer, D. Bouša, R. S. Varma, M. B. Gawande and R. Zbořil, "Fe(0)-embedded thermally reduced graphene oxide as efficient nanocatalyst for reduction of nitro compounds to amines," CHEMICAL ENGINEERING JOURNAL, vol. 382, p. 122469, 2020.
DOI: 10.1016/j.cej.2019.122469, IF = 13.273
Abstract: The recent progress in metal nanoparticle-based catalytic systems has prompted the research community to focus on combining the unique physicochemical properties with their catalytic activities. In this context, magnetic nanomaterials offer significant advantage as they can be separated after the catalytic reaction and reused. Among such systems, Fe-based nanoparticles are undeniably the most popular as they can be synthesized from the earth-abundant resources. However, in view of the poor chemical stability of nanoscale zero-valent iron (nZVI) particles during the reaction process, their use in advanced catalytic systems is still challenging. Herein, we present a Fe(0) species embedded in a thermally reduced graphene oxide matrix (Fe/TRGO) as a nanocatalyst for the reduction of nitro compounds. The catalyst exhibits high substrate scope with high yield and selectivity and can be recycled up to four times without any significant loss in activity. The unique rGO (reduced graphene oxide)-entrapped doughnut-shaped structure of the Fe(0) species, accompanied by the thin oxide protection layer, is responsible for the superior catalytic activity. Due to the scalable synthesis and high catalytic efficiency the catalyst offers a real application potential in industrial transformations of nitro compounds.
E. Vermisoglou, D. Panáček, K. Jayaramulu, M. Pykal, I. Frébort, M. Kolář, M. Hajdúch, R. Zbořil and M. Otyepka, "Human virus detection with graphene-based materials," BIOSENSORS AND BIOELECTRONICS, vol. 166, pp. 112436, 2020.
DOI: 10.1016/j.bios.2020.112436, IF = 10.618
Abstract: Our recent experience of the COVID-19 pandemic has highlighted the importance of easy-to-use, quick, cheap, sensitive and selective detection of virus pathogens for the efficient monitoring and treatment of virus diseases. Early detection of viruses provides essential information about possible efficient and targeted treatments, prolongs the therapeutic window and hence reduces morbidity. Graphene is a lightweight, chemically stable and conductive material that can be successfully utilized for the detection of various virus strains. The sensitivity and selectivity of graphene can be enhanced by its functionalization or combination with other materials. Introducing suitable functional groups and/or counterparts in the hybrid structure enables tuning of the optical and electrical properties, which is particularly attractive for rapid and easy-to-use virus detection. In this review, we cover all the different types of graphene-based sensors available for virus detection, including, e.g., photoluminescence and colorimetric sensors, and surface plasmon resonance biosensors. Various strategies of electrochemical detection of viruses based on, e.g., DNA hybridization or antigen-antibody interactions, are also discussed. We summarize the current state-of-the-art applications of graphene-based systems for sensing a variety of viruses, e.g., SARS-CoV-2, influenza, dengue fever, hepatitis C virus, HIV, rotavirus and Zika virus. General principles, mechanisms of action, advantages and drawbacks are presented to provide useful information for the further development and construction of advanced virus biosensors. We highlight that the unique and tunable physicochemical properties of graphene-based nanomaterials make them ideal candidates for engineering and miniaturization of biosensors.
E. N. Zare, V. V. Padil, B. Mokhtari, A. Venkateshaiah, S. Wacławek, M. Černík, F. R. Tay, R. S. Varma and P. Makvandi, "Advances in biogenically synthesized shaped metal- and carbon-based nanoarchitectures and their medicinal applications," ADVANCES IN COLLOID AND INTERFACE SCIENCE, vol. 283, pp. 102236, 2020.
DOI: 10.1016/j.cis.2020.102236, IF = 12.984
Abstract: Non-spherical metal-based and carbon-based nanostructures have found applications in every facet of scientific endeavors, including engineering and biomedical fields. These nanostructures attract attention because of their biocompatibility and negligible cytotoxicity. Chemical and physical methods have been used for synthesizing earlier generations of metal-based and carbon-based nanostructures with variable architectures, including nanorods, nanowires, nanodots and nanosheets. However, these synthesis strategies utilize organic passivators which are toxic to the environment and the human body. Biogenic synthesis of nanoparticles is becoming increasing popular because of the necessity to develop eco-friendly and non-toxic strategies. Nanoparticles synthesized by natural compounds have immense potential in the biomedical arena. The present review focuses on plant-mediated synthesis of metal-based and carbon-based non-spherical nanoarchitectures and the role of green synthesis in improving their activities for biomedical applications.
A. S. Sharma, V. S. Sharma, H. Kaur and R. S. Varma, "Supported heterogeneous nanocatalysts in sustainable, selective and eco-friendly epoxidation of olefins," GREEN CHEMISTRY, vol. 22, iss. 18, pp. 5902-5936, 2020.
DOI: 10.1039/d0gc01927e, IF = 10.182
Abstract: Epoxides are highly useful intermediates in the production of many chemicals, pharmaceuticals, perfumes, and polymers. In view of the continuing demand for epoxides, it is imperative to develop greener and sustainable reaction protocols. To address these challenges, highly active, selective and efficient heterogeneous catalysts have been designed. Historically, there has been a progressive replacement of hazardous peracids and chlorohydrin-based epoxidation of olefins by metal catalysts deploying tert-butyl hydroperoxide (TBHP), hydrogen peroxide (H2O2) and molecular oxygen (O2) as oxidants. The main focus of this review is to epitomize the wide scope of supported metal nanocatalysts that have been applied for the epoxidation of olefins. The synthesis, activity and selectivity of the nanocatalytic materials along with a critical appraisal of the performance of the support in the epoxidation of olefins are accentuated.
S. Kumar, M. B. Gawande, I. Medřík, M. Petr, O. Tomanec, V. Kupka, R. S. Varma and R. Zbořil, "Mechanochemical synthesis of Cu2S bonded 2D-sulfonated organic polymers: continuous production of dimethyl carbonate (DMC) via preheating of reactants," GREEN CHEMISTRY, vol. 22, iss. 17, pp. 5619-5627, 2020.
DOI: 10.1039/d0gc01030h, IF = 10.182
Abstract: The vital need for an external dehydrating agent in high-yield production of dimethyl carbonate (DMC) has been circumvented via in situ formation of copper sulfide (Cu2S) bonded 2D-sulfonated organic polymers, Cu-SOPm and Cu-SOPs, by deploying single-step and solvent-assisted mechanochemical and solvothermal methods, respectively. Cu-SOPm exhibited excellent catalytic activity for the continuous production of DMC from carbon dioxide and methanol without using a dehydrating agent. The presence of a higher amount of sulfonic acid groups (–SO3H) is the key factor, which can adsorb the ensuing water during the reaction thus shifting reaction equilibrium in the forward direction; Cu-SOPs is relatively less active catalytically owing to a smaller amount of sulfonic groups. All the reactions are accomplished on a high-pressure fixed-bed flow reactor and the effects of various reaction parameters (flow rate, catalyst amount, system temperature and pressure) are investigated, especially the preheating of the CO2 and CH3OH mixture, which facilitated methanol conversion considerably, and afforded 42.8% yield of DMC with 100% selectivity. The preparation of the catalysts and formation of DMC were supported by a plausible mechanism wherein increased residence time and high reaction pressure always favored the methanol conversion. This study enables the continuous high-yield generation of DMC under flow conditions deploying preheating of substrates and concomitantly addressing the lingering problem for designing a built-in dehydrating capability in the catalyst.
S. E. Hooshmand, R. Afshari, D. J. Ramón and R. S. Varma, "Deep eutectic solvents: cutting-edge applications in cross-coupling reactions," GREEN CHEMISTRY, vol. 22, iss. 12, pp. 3668-3692, 2020.
DOI: 10.1039/d0gc01494j, IF = 10.182
Abstract: Deep eutectic solvents (DESs), surmised as “the organic reaction medium of the century”, have reverberated a new symphony throughout the present green millennium. A brief historical account of the DES systems and their physicochemical properties as task-specific and designer solvents for cross-coupling reactions are appraised including the hole theory that explains the underlying mechanistic pathway for this emerging neoteric medium. The insights into cross-coupling reactions and their applications are included, highlighting the significant achievements pertaining to the dual role of DESs as a solvent and catalyst. In addition, popular “name-reactions” for the carbon–carbon and carbon–heteroatom bond formations related to the nature of DESs and the core optimum conditions are included. The review also encompasses the novel approaches to privileged catalytic systems and identify the voids left in cross-coupling reactions where DES systems have not made inroads yet. Finally, the challenges of utilizing the neoteric derivatives of DES for these reactions are expounded.
S. Iravani and R. S. Varma, "Sustainable synthesis of cobalt and cobalt oxide nanoparticles and their catalytic and biomedical applications," GREEN CHEMISTRY, vol. 22, iss. 9, pp. 2643-2661, 2020.
DOI: 10.1039/d0gc00885k, IF = 10.182
Abstract: Cobalt and cobalt oxide NPs are gaining diverse catalytic and biomedical applications, because of their unique antimicrobial, anticancer, catalytic, antioxidant, antifungal, and enzyme inhibition properties. Generally, various physicochemical approaches have been employed for the fabrication of these nanoparticles, but because of their considerable disadvantages such as toxicity and time consuming reactions, there is a demand for the development of safer, greener, eco-friendly, and cost-effective synthetic methods; greener tactics can eliminate the arduousness and complications of physicochemical methods. In this critical review, noteworthy recent advancements pertaining to the catalytic and biomedical applications of green-synthesized cobalt and cobalt oxide nanoparticles are highlighted along with their sustainable synthesis options.
A. Venkateshaiah, J. Y. Cheong, S. Shin, K. P. Akshaykumar, T. G. Yun, J. Bae, S. Wacławek, M. Černík, S. Agarwal, A. Greiner, V. V. T. Padil, I. Kim and R. S. Varma, "Recycling non-food-grade tree gum wastes into nanoporous carbon for sustainable energy harvesting," GREEN CHEMISTRY, vol. 22, iss. 4, pp. 1198-1208, 2020.
DOI: 10.1039/c9gc04310a, IF = 10.182
Abstract: The disposal of natural wastes has become a global problem and the use of lower-grade gums is very limited owing to their impurities as well as sticky nature. Rather than disposing these wastes, nanoporous carbon (nC) has instead been synthesized by carbonization and exfoliation. The synthesized nC exhibits a substantially high surface area along with abundant micro/mesopores. This desirable and useful nature of nC is well-suited for water-driven effective electrical energy conversion, which enables the fast evaporation of water via a capillary action through nanopores. Under asymmetric wetting in a water container and ambient conditions, the nC-based energy harvesters showed high capability of electricity production and reliable output generation, easily turning on a blue light-emitting diode (2.5 V and 20 mA) using a stored power source. In summary, many energy harvesters can be manufactured for the scale-up of electricity, and the suitability of regenerated carbon nanomaterials for green energy harvesting can contribute toward alleviating chronic environmental issues.
S. Iravani and R. S. Varma, "Greener synthesis of lignin nanoparticles and their applications," GREEN CHEMISTRY, vol. 22, iss. 3, pp. 612-636, 2020.
DOI: 10.1039/c9gc02835h, IF = 10.182
Abstract: The remarkable absorption capacity, biodegradability and non-toxicity of lignin nanoparticles enable them to be appropriate vehicles for drug molecules and inorganic particles. Lignin nanoparticles have potential applications in the biomedical and environmental fields, such as tissue engineering or regeneration, artificial muscles, and strong underwater antifouling materials. Additionally, the synthesis of nanoparticles using physicochemical methods can generate toxic and hazardous effects in the environment and often need expensive materials and instruments. Thus, applications of cost-effective, safer, simple, sustainable and eco-friendly approaches for fabricating nanoparticles which comply with the “green chemistry” principles are very important. In this review, significant recent advancements pertaining to the biomedical and therapeutic applications of lignin nanoparticles are highlighted including their greener synthetic options.
E. Y. C. Jorge, C. G. S. Lima, T. M. Lima, L. Marchini, M. B. Gawande, O. Tomanec, R. S. Varma and M. W. Paixão, "Sulfonated dendritic mesoporous silica nanospheres: a metal-free Lewis acid catalyst for the upgrading of carbohydrates," GREEN CHEMISTRY, vol. 22, iss. 5, pp. 1754-1762, 2020.
DOI: 10.1039/c9gc03489g, IF = 10.182
Abstract: Lignocellulosic biomass is becoming a viable alternative or complementary source for obtaining petroleum-derived products such as fuels, polymers and fine chemicals, among others. Nevertheless, the successful upgrading of lignocellulosics requires the design of efficient and robust catalysts, where sulfonated mesoporous silica materials may be an ideal choice for exploration. Herein, we have conducted the upgrading of several mono-, di- and polysaccharides such as xylose, fructose, glucose, sucrose and cellulose to valuable platform chemicals using a novel catalyst comprising sulfonated dendritic mesoporous silica nanospheres. Additionally, a thorough comparative study was conducted encompassing arrays of sulfonated silicas as catalysts with the aim of relating their activities and appreciating the features which could be responsible for their activity.
Y. Chen, Y. Meng, Y. Dong, X. Song, G. Huang, C. Zhang, Z. Ni, J. Navařík, O. Malina, R. Zbořil and M. Tong, "Light- and temperature-assisted spin state annealing: accessing the hidden multistability," CHEMICAL SCIENCE, vol. 11, iss. 12, pp. 3281-3289, 2020.
DOI: 10.1039/c9sc05971g, IF = 9.825
Abstract: Among responsive multistable materials, spin crossover (SCO) systems are of particular interest for stabilizing multiple spin states with various stimulus inputs and physical outputs. Here, in a 2D Hofmann-type coordination polymer, [Fe(isoq)2{Au(CN)2}2] (isoq = isoquinoline), a medium-temperature annealing process is introduced after light/temperature stimulation, which accesses the hidden multistability of the spin state. With the combined effort of magnetic, crystallographic and Mössbauer spectral investigation, these distinct spin states are identified and the light- and temperature-assisted transition pathways are clarified. Such excitation-relaxation and trapping-relaxation joint mechanisms, as ingenious interplays between the kinetic and thermodynamic effects, uncover hidden possibilities for the discovery of multistable materials and the development of multistate intelligent devices.
T. Senthamarai, V. G. Chandrashekhar, M. B. Gawande, N. V. Kalevaru, R. Zbořil, P. C. J. Kamer, R. V. Jagadeesh and M. Beller, "Ultra-small cobalt nanoparticles from molecularly-defined Co–salen complexes for catalytic synthesis of amines," CHEMICAL SCIENCE, vol. 11, iss. 11, pp. 2973-2981, 2020.
DOI: 10.1039/c9sc04963k, IF = 9.825
Abstract: We report the synthesis of in situ generated cobalt nanoparticles from molecularly defined complexes as efficient and selective catalysts for reductive amination reactions. In the presence of ammonia and hydrogen, cobalt–salen complexes such as cobalt(II)–N,N′-bis(salicylidene)-1,2-phenylenediamine produce ultra-small (2–4 nm) cobalt-nanoparticles embedded in a carbon–nitrogen framework. The resulting materials constitute stable, reusable and magnetically separable catalysts, which enable the synthesis of linear and branched benzylic, heterocyclic and aliphatic primary amines from carbonyl compounds and ammonia. The isolated nanoparticles also represent excellent catalysts for the synthesis of primary, secondary as well as tertiary amines including biologically relevant N-methyl amines.
T. Malina, E. Maršálková, K. Holá, R. Zbořil and B. Maršálek, "The environmental fate of graphene oxide in aquatic environment—Complete mitigation of its acute toxicity to planktonic and benthic crustaceans by algae," JOURNAL OF HAZARDOUS MATERIALS, vol. 399, pp. 123027, 2020.
DOI: 10.1016/j.jhazmat.2020.123027, IF = 10.588
Abstract: Graphene oxide (GO) as the most studied hydrophilic graphene derivative can be deployed in a broad spectrum of environmental technologies opening the issue of its ecotoxicity. Nevertheless, the information about its behavior in complex aquatic environment is still not sufficient. Here, we studied the interaction of three differently oxidized GO systems with planktonic and benthic crustaceans. By standard toxicity tests, we observed the importance of feeding strategy as well as the surface oxidation of GO with respect to GO’s ecotoxicity. However, to gain a clearer insight into GO’s environmental fate, we introduced a pre-treatment with algae as the most common source of food for crustaceans. Such an adjustment mimicking the conditions in real aquatic ecosystems resulted in complete mitigation of acute toxicity of GOs to all organisms and, more importantly, to the eradication of oxidative stress caused by GOs. We argue, that the pre-exposition of food is a crucial factor in GO’s overall environmental fate, even though this fact has been completely neglected in recent studies. These experiments proved that GO is not a hazardous material in complex aquatic environments because its acute toxicity can be successfully mitigated through the interaction with algae even at very high concentrations (25 mg/L).
D. Hermosilla, C. Han, M. N. Nadagouda, L. Machala, A. Gascó, P. Campo and D. D. Dionysiou, "Environmentally friendly synthesized and magnetically recoverable designed ferrite photo-catalysts for wastewater treatment applications," JOURNAL OF HAZARDOUS MATERIALS, vol. 381, p. 121200, 2020.
DOI: 10.1016/j.jhazmat.2019.121200, IF = 10.588
Abstract: Fenton processes are promising wastewater treatment alternatives for bio-recalcitrant compounds. Three different methods (i.e., reverse microemulsion, sol-gel, and combustion) were designed to synthesize environmentally friendly ferrites as magnetically recoverable catalysts to be applied for the decomposition of two pharmaceuticals (ciprofloxacin and carbamazepine) that are frequently detected in water bodies. The catalysts were used in a heterogeneous solar photo-Fenton treatment to save the cost of applying high-energy UV radiation sources, and was performed under a slightly basic pH to avoid metal leaching and adding salts for pH adjustment. All the developed catalysts resulted in the effective treatment of ciprofloxacin and carbamazepine in both synthetic and real domestic wastewater. In particular, the sol-gel synthesized ferrite was more magnetic and more suitable for reuse. The degradation pathways of both compounds were elucidated for this treatment. The degradation of ciprofloxacin involved attacks to the quinolone and piperazine rings. The degradation pathway of carbamazepine involved the formation of hydroxyl carbamazepine and dihydroxy carbamazepine before yielding acridine by hydrogen abstraction, decarboxylation, and amine cleavage, which would be further oxidized.
R. Langer, P. Błoński, C. Hofer, P. Lazar, K. Mustonen, J. C. Meyer, T. Susi and M. Otyepka, "Tailoring Electronic and Magnetic Properties of Graphene by Phosphorus Doping," ACS APPLIED MATERIALS & INTERFACES, vol. 12, iss. 30, pp. 34074-34085, 2020.
DOI: 10.1021/acsami.0c07564, IF = 9.229
Abstract: The electronic and magnetic properties of graphene can be modulated by doping it with other elements, especially those with a different number of valence electrons. In this article, we first provide a three-dimensional reconstruction of the atomic structure of a phosphorus substitution in graphene using aberration-corrected scanning transmission electron microscopy. Turning then to theoretical calculations based on the density functional theory (DFT), we show that doping phosphorus in various bonding configurations can induce magnetism in graphene. Our simulations reveal that the electronic and magnetic properties of P-doped (Gr-P) and/or phosphono-functionalized graphene (Gr-PO3H2) can be controlled by both the phosphorus concentration and configurations, ultimately leading to ferromagnetic (FM) and/or antiferromagnetic (AFM) features with the transition temperature up to room temperature. We also calculate core-level binding energies of variously bonded P to facilitate X-ray photoelectron spectroscopy-based identification of its chemical form present in P-doped graphene-based structures. These results may enable the design of graphene-based organic magnets with tailored properties for future magnetic or spintronic applications.
K. Zhang, K. O. Kirlikovali, R. S. Varma, Z. Jin, H. W. Jang, O. K. Farha and M. Shokouhimehr, "Covalent Organic Frameworks: Emerging Organic Solid Materials for Energy and Electrochemical Applications," ACS APPLIED MATERIALS & INTERFACES, vol. 12, iss. 25, pp. 27821-27852, 2020.
DOI: 10.1021/acsami.0c06267, IF = 9.229
Abstract: Covalent organic frameworks (COFs), materials constructed from organic building blocks joined by robust covalent bonds, have emerged as attractive materials in the context of electrochemical applications because of their high, intrinsic porosities and crystalline frameworks, as well as their ability to be tuned across two- and three-dimensions by the judicious selection of building blocks. Because of the recent and rapid development of this field, we have summarized COFs employed for electrochemical applications, such as batteries and capacitors, water splitting, solar cells, and sensors, with an emphasis on the structural design and resulting performance of the targeted electrochemical system. Overall, we anticipate this review will stimulate the design and synthesis of the next generation of COFs for use in electrochemical applications and beyond.
V. Urbanová, P. Lazar, N. Antonatos, Z. Sofer, M. Otyepka and M. Pumera, "Positive and Negative Effects of Dopants toward Electrocatalytic Activity of MoS2 and WS2: Experiments and Theory," ACS APPLIED MATERIALS & INTERFACES, vol. 12, iss. 18, pp. 20383-20392, 2020.
DOI: 10.1021/acsami.0c00983, IF = 9.229
Abstract: Two-dimensional transition-metal dichalcogenides (TMDs) are lately in the scope within the scientific community owing to their exploitation as affordable catalysts for next-generation energy devices. Undoubtedly, only precise tailoring and control over the catalytic properties can ensure high efficiency and successful implementation of such devices in day-to-day practical utilization. However, contrary to theoretical predictions, systematic experimental work dealing with the doped materials and their impact to electrocatalysis are relatively underrated despite the considerable effect that it could bring into this field. Herein, we investigate the effect of four different dopants (i.e., Ti, V, Mn, and Fe) incorporated to both layered MoS2 and WS2 as solid-state solution toward their electrocatalytic performance through their evaluation as catalysts for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). Our results pointed out that doping by Mn and Fe can enhance the electrocatalytic performance toward ORR, whereas doping by Ti and V revealed poor electrocatalytic effects (inhibition) compared to both undoped MoS2 and WS2. Surprisingly, none of the dopants contributed to the improvement of either MoS2 or WS2 toward HER activity. Therefore, in addition to the experimental data, density functional theory calculations were performed to further investigate the role of the dopants in the performance of MoS2 toward HER. According to these calculations, all dopants preferably occupied the edges of the crystal structure and thus could affect the electrocatalytic properties of the initial material. However, the observed ΔG values for hydrogen adsorption revealed that MoS2 is the best catalyst with a subsequent trend for doped materials following the less negative binding energies V < Ti < Mn < Fe, which was in good agreement with experimentally obtained overpotentials of the respective samples. This study thus elucidates the reasons for negative effects of doping in TMDs. This study brings an insight that not all dopants are beneficial and not all reactions are affected in the same way by dopants in TMDs.
M. Brumovský, J. Filip, O. Malina, J. Oborná, O. Sracek, T. G. Reichenauer, P. Andrýsková and R. Zbořil, "Core–Shell Fe/FeS Nanoparticles with Controlled Shell Thickness for Enhanced Trichloroethylene Removal," ACS APPLIED MATERIALS & INTERFACES, vol. 12, iss. 31, pp. 35424-35434, 2020.
DOI: 10.1021/acsami.0c08626, IF = 9.229
Abstract: Zero-valent iron nanoparticles (nZVI) treated by reduced sulfur compounds (i.e., sulfidated nZVI, S-nZVI) have attracted increased attention as promising materials for environmental remediation. While the preparation of S-nZVI and its reactions with various groundwater contaminants such as trichloroethylene (TCE) were already a subject of several studies, nanoparticle synthesis procedures investigated so far were suited mainly for laboratory-scale preparation with only a limited possibility of easy and cost-effective large-scale production and FeS shell property control. This study presents a novel approach for synthesizing S-nZVI using commercially available nZVI particles that are treated with sodium sulfide in a concentrated slurry. This leads to S-nZVI particles that do not contain hazardous boron residues and can be easily prepared off-site. The resulting S-nZVI exhibits a core–shell structure where zero-valent iron is the dominant phase in the core, while the shell contains mostly amorphous iron sulfides. The average FeS shell thickness can be controlled by the applied sulfide concentration. Up to a 12-fold increase in the TCE removal and a 7-fold increase in the electron efficiency were observed upon amending nZVI with sulfide. Although the FeS shell thickness correlated with surface-area-normalized TCE removal rates, sulfidation negatively impacted the particle surface area, resulting in an optimal FeS shell thickness of approximately 7.3 nm. This corresponded to a particle S/Fe mass ratio of 0.0195. At all sulfide doses, the TCE degradation products were only fully dechlorinated hydrocarbons. Moreover, a nearly 100% chlorine balance was found at the end of the experiments, further confirming complete TCE degradation and the absence of chlorinated transformation products. The newly synthesized S-nZVI particles thus represent a promising remedial agent applicable at sites contaminated with TCE.
H. Ning, L. Jing, Y. Hou, S. Kalytchuk, Y. Li, X. Huang and M. Gao, "Manganese-Mediated Growth of ZnS Shell on KMnF3:Yb,Er Cores toward Enhanced Up/Downconversion Luminescence," ACS APPLIED MATERIALS & INTERFACES, vol. 12, iss. 10, pp. 11934-11944, 2020.
DOI: 10.1021/acsami.9b21832, IF = 9.229
Abstract: Epitaxially growing a semiconductor shell on the surface of upconversion nanocrystals to form a core/shell structure is believed to be a promising strategy to improve the luminescent efficiency of lanthanide ions doped in particle cores and, meanwhile, enriches the optical properties of the resulting nanocrystals. However, liquid-phase synthesis of such core/shell-structured nanocrystals comprised of a lanthanide ion-doped core and semiconductor shell remains challenging because of the chemical incompatibilities between lanthanides and the most intermediate gap semiconductors. In this context, the successful growth of ZnS shell on a KMnF3 core codoped with Yb3+/Er3+ ions is reported to enhance the upconversion luminescence of Er3+ ions. The underlying core/shell formation mechanism is elucidated in detail combining the hard–soft acid–base theory with structural analysis of the resulting nanocrystals. Quite unexpectedly, Mn2+ diffusion across the core/shell interface occurs during ZnS shell growth, giving rise to Mn2+ emission from the ZnS shell. Thus, the resulting core/shell particles exhibited unique up/downconversion luminescence from doped lanthanide metal ions and transition-metal ions, respectively. By manipulating the ion diffusion and shell growth kinetics, the upconversion and downconversion luminescent performance of KMnF3:Yb,Er@ZnS nanocrystals are further optimized and the related mechanisms are discussed. Further, temperature-dependent upconversion and downconversion photoluminescence properties of KMnF3:Yb,Er@ZnS nanocrystals show potential for ratiometric luminescence temperature sensing.
B. Reuillard, M. Blanco, L. Calvillo, N. Coutard, A. Ghedjatti, P. Chenevier, S. Agnoli, M. Otyepka, G. Granozzi and V. Artero, "Noncovalent Integration of a Bioinspired Ni Catalyst to Graphene Acid for Reversible Electrocatalytic Hydrogen Oxidation," ACS APPLIED MATERIALS & INTERFACES, vol. 12, iss. 5, pp. 5805-5811, 2020.
DOI: 10.1021/acsami.9b18922, IF = 9.229
Abstract: Efficient heterogeneous catalysis of hydrogen oxidation reaction (HOR) by platinum group metal (PGM)-free catalysts in proton-exchange membrane (PEM) fuel cells represents a significant challenge toward the development of a sustainable hydrogen economy. Here, we show that graphene acid (GA) can be used as an electrode scaffold for the noncovalent immobilization of a bioinspired nickel bis-diphosphine HOR catalyst. The highly functionalized structure of this material and optimization of the electrode-catalyst assembly sets new benchmark electrocatalytic performances for heterogeneous molecular HOR, with current densities above 30 mA cm–2 at 0.4 V versus reversible hydrogen electrode in acidic aqueous conditions and at room temperature. This study also shows the great potential of GA for catalyst loading improvement and porosity management within nanostructured electrodes toward achieving high current densities with a noble-metal free molecular catalyst.
H. Seelajaroen, A. Bakandritsos, M. Otyepka, R. Zbořil and N. S. Sariciftci, "Immobilized Enzymes on Graphene as Nanobiocatalyst," ACS APPLIED MATERIALS & INTERFACES, vol. 12, iss. 1, pp. 250-259, 2020.
DOI: 10.1021/acsami.9b17777, IF = 9.229
Abstract: Using enzymes as bioelectrocatalysts is an important step toward the next level of biotechnology for energy production. In such biocatalysts, a sacrificial cofactor as an electron and proton source is needed. This is a great obstacle for upscaling, due to cofactor instability and product separation issues, which increase the costs. Here, we report a cofactor-free electroreduction of CO2 to a high energy density chemical (methanol) catalyzed by enzyme–graphene hybrids. The biocatalyst consists of dehydrogenases covalently bound on a well-defined carboxyl graphene derivative, serving the role of a conductive nanoplatform. This nanobiocatalyst achieves reduction of CO2 to methanol at high current densities, which remain unchanged for at least 20 h of operation, without production of other soluble byproducts. It is thus shown that critical improvements on the stability and rate of methanol production at a high Faradaic efficiency of 12% are possible, due to the effective electrochemical process from the electrode to the enzymes via the graphene platform.
R. Rautela, S. Scarfe, J. Guay, P. Lazar, M. Pykal, S. Azimi, C. Grenapin, J. Boddison-Chouinard, A. Halpin, W. Wang, L. Andrzejewski, R. Plumadore, J. Park, J. Menard, M. Otyepka and A. Luican-Mayer, "Mechanistic insight into the limiting factors of graphene-based environmental sensors," ACS APPLIED MATERIALS & INTERFACES, vol. 12, iss. 35, pp. 39764-39771, 2020.
DOI: 10.1021/acsami.0c09051, IF = 9.229
Abstract: Graphene has demonstrated great promise for technological use, yet control over material growth and understanding of how material imperfections affect the performance of devices are challenges that hamper the development of applications. In this work we reveal new insight into the connections between the performance of the graphene devices as environmental sensors and the microscopic details of the interactions at the sensing surface. We monitor changes in the resistance of the chemical-vapour deposition grown graphene devices as exposed to different concentrations of ethanol. We perform thermal surface treatments after the devices are fabricated, use scanning probe microscopy to visualize their effects down to nanometer scale and correlate them with the measured performance of the device as an ethanol sensor. Our observations are compared to theoretical calculations of charge transfers between molecules and the graphene surface. We find that, although often overlooked, the surface cleanliness after device fabrication is responsible for the device performance and reliability. These results further our understanding of the mechanisms of sensing in graphene-based environmental sensors and pave the way to optimizing such devices, especially for their miniaturization, as with decrising size of the active zone the potential role of contaminants will rise.
R. Langer, E. Fako, P. Błoński, M. Vavrečka, A. Bakandritsos, M. Otyepka and N. López, "Anchoring of single-platinum-adatoms on cyanographene: Experiment and theory," APPLIED MATERIALS TODAY, vol. 18, p. 100462, 2020.
DOI: 10.1016/j.apmt.2019.100462, IF = 10.041
Abstract: Graphene decorated with isolated single atoms (SAs) offers new vista to magnetic and spintronic devices up to single-atom catalysts. While sp atoms can be efficiently bound to graphene, d-block atoms require anchoring groups to prevent nanoparticle formation. Identification of suitable binding sites is a challenging task because the interaction among graphene, anchoring groups and adatoms is very complex. Using density functional theory (DFT) we explored strength and nature of interactions of graphene covalently functionalized by −OH, −CN, −F, and −H groups as anchors for Pt SAs. Both theory and experiment showed that −CN groups acted as suitable ligand enabling immobilization of 3.7 wt % single Pt adatoms. The findings imply that CN functionalized graphene, i.e., cyanographene, is a perspective material for anchoring metal adatoms with potential implications as single-atom-catalysts.
R. Ahmad, G. V. Nutan, D. Singh, G. Gupta, U. Soni, S. Sapra and R. Srivastava, "Colloidal lead-free Cs2AgBiBr6 double perovskite nanocrystals: Synthesis, uniform thin-film fabrication, and application in solution-processed solar cells," NANO RESEARCH, 2020.
DOI: 10.1007/s12274-020-3161-6, IF = 8.897
Abstract: Recently developed lead-free double perovskite nanocrystals (NCs) have been proposed for the possible application in solution-processed optoelectronic devices. However, the optoelectronic applications of double perovskite NCs have been hampered due to the structural and chemical instability in the presence of polar molecules. Here, we report a facile strategy for the synthesis and purification of Cs2AgBiBr6 double perovskite NCs that remained stable even after washing with polar solvent. This is realized with our efficient colloidal route to synthesize Cs2AgBiBr6 NCs that involve stable and strongly coordinated precursor such as silver-trioctylphosphine complex together with bismuth neodecanoate, which leads to a significantly improved chemical and colloidal stability. Using layer-by-layer solid-state ligand exchange technique, a compact and crack-free thin film of Cs2AgBiBr6 NCs were fabricated. Finally, perovskite solar cells consisting of Cs2AgBiBr6 as an absorber layer were fabricated and tested.
T. Su, D. Zhao, Y. Wang, H. Lü, R. S. Varma and C. Len, "Innovative Protocols in the Catalytic Oxidation of 5‐Hydroxymethylfurfural," CHEMSUSCHEM, Article in press, 2020.
DOI: 10.1002/cssc.202002232, IF = 8.928
Abstract: 5‐Hydroxymethylfurfural (HMF) has been identified as one of the most promising biomass‐based multi‐purpose platform molecules. Innovative protocols, namely electrocatalysis, photocatalysis, and microwave (MW)‐assisted chemistry, as well as continuous‐flow systems, add a new dimension and another promising toolbox for the oxidation of HMF in recent years. This Minireview deals with recent progress in the catalytic oxidation of HMF to 2,5‐furandicarboxylic acid (FDCA) and other intermediates using noble, non‐noble, and metal‐free systems deploying emerging protocols. Selective HMF downstream oxidation products could be obtained not only via common catalyst modifications, namely nature of the metal, preparative method, and the property of deployed support, but also by using innovative processes.
S. Kumar, M. B. Gawande, J. Kopp, S. Kment, R. S. Varma and R. Zbořil, "P‐ and F‐co‐doped Carbon Nitride Nanocatalysts for Photocatalytic CO2Reduction and Thermocatalytic Furanics Synthesis from Sugars," CHEMSUSCHEM, vol. 13, iss. 19, pp. 5231-5238, 2020.
DOI: 10.1002/cssc.202001172, IF = 8.928
Abstract: A new P‐ and F‐co‐doped amorphous carbon nitride (PFCN) has been synthesized via sol‐gel‐mediated thermal condensation of dicyandiamide. Such synthesized P‐ and F‐co‐doped carbon nitride displayed a well‐defined mesoporous nanostructure and enhanced visible light absorption region up to infrared with higher BET surface area of 260.93 m2 g−1; the highest recorded value for phosphorus‐doped carbon nitride materials. Moreover, the formation mechanism is delineated and the role of templates was found to be essential not only in increasing the surface area but also in facilitating the co‐doping of P and F atoms. Co‐doping helped to narrow the optical band gap to 1.8 eV, thus enabling an excellent photocatalytic activity for the aqueous reduction of carbon dioxide into methanol under visible‐light irradiation, which is fifteen times higher (119.56 μmol g−1 h−1) than the bare carbon nitride. P doping introduced Brønsted acidity into the material, turning it into an acid‐base bifunctional catalyst. Consequently, the material was also investigated for the thermal conversion of common carbohydrates into furanics.
R. S. Almeida Ribeiro, L. E. Monteiro Ferreira, V. Rossa, C. G. S. Lima, M. W. Paixão, R. S. Varma and T. Melo Lima, "Graphitic Carbon Nitride‐Based Materials as Catalysts for the Upgrading of Lignocellulosic Biomass‐Derived Molecules," CHEMSUSCHEM, vol. 13, iss. 16, pp. 3992-4004, 2020.
DOI: 10.1002/cssc.202001017, IF = 8.928
Abstract: The use of graphitic carbon nitride (g‐C3N4)‐based catalysts in the upgrading of lignocellulosic biomass significantly contributes to the greener production of biofuels, polymer precursors, and building blocks. In recent years, several catalysts based on g‐C3N4 have been developed and applied in both photocatalyzed and non‐photocatalyzed (thermal) reactions. This Review provides an overview on the upgrading of lignocellulosic biomass deploying several compositions of g‐C3N4‐based catalysts.
Y. Monga, P. Kumar, R. K. Sharma, J. Filip, R. S. Varma, R. Zbořil and M. B. Gawande, "Sustainable Synthesis of Nanoscale Zerovalent Iron Particles for Environmental Remediation," CHEMSUSCHEM, vol. 13, iss. 13, pp. 3288-3305, 2020.
DOI: 10.1002/cssc.202000290, IF = 8.928
Abstract: Nanoscale zerovalent iron (nZVI) particles represent an important material for diverse environmental applications because of their exceptional electron‐donating properties, which can be exploited for applications such as reduction, catalysis, adsorption, and degradation of a broad range of pollutants. The synthesis and assembly of nZVI by using biological and natural sustainable resources is an attractive option for alleviating environmental contamination worldwide. In this Review, various green synthesis pathways for generating nZVI particles are summarized and compared with conventional chemical and physical methods. In addition to describing the latest environmentally benign methods for the synthesis of nZVI, their properties and interactions with diverse biomolecules are discussed, especially in the context of environmental remediation and catalysis. Future prospects in the field are also considered.
A. Taheri-Kafrani, S. Kharazmi, M. Nasrollahzadeh, A. Soozanipour, F. Ejeian, P. Etedali, H. Mansouri-Tehrani, A. Razmjou, S. M. Yek and R. S. Varma, "Recent developments in enzyme immobilization technology for high-throughput processing in food industries," CRITICAL REVIEWS IN FOOD SCIENCE AND NUTRITION, Article in press, 2020.
DOI: 10.1080/10408398.2020.1793726, IF = 7.862
Abstract: The demand for food and beverage markets has increased as a result of population increase and in view of health awareness. The quality of products from food processing industry has to be improved economically by incorporating greener methodologies that enhances the safety and shelf life via the enzymes application while maintaining the essential nutritional qualities. The utilization of enzymes is rendered more favorable in industrial practices via the modification of their characteristics as attested by studies on enzyme immobilization pertaining to different stages of food and beverage processing; these studies have enhanced the catalytic activity, stability of enzymes and lowered the overall cost. However, the harsh conditions of industrial processes continue to increase the propensity of enzyme destabilization thus shortening their industrial lifespan namely enzyme leaching, recoverability, uncontrollable orientation and the lack of a general procedure. Innovative studies have strived to provide new tools and materials for the development of systems offering new possibilities for industrial applications of enzymes. Herein, an effort has been made to present up-to-date developments on enzyme immobilization and current challenges in the food and beverage industries in terms of enhancing the enzyme stability.
J. Semerád, J. Filip, A. Ševců, M. Brumovský, N. H. A. Nguyen, J. Mikšíček, T. Lederer, A. Filipová, J. Boháčková and T. Cajthaml, "Environmental fate of sulfidated nZVI particles: the interplay of nanoparticle corrosion and toxicity during aging," ENVIRONMENTAL SCIENCE: NANO, vol. 7, iss. 6, pp. 1794-1806, 2020.
DOI: 10.1039/d0en00075b, IF = 8.131
Abstract: Nanomaterials have attracted research attention due to their unique properties, which have also made them increasingly useful for various applications, including remediation technologies. In this work, we tried to explore the aging phenomenon of several newly developed nanoscale zero-valent iron (nZVI) particles containing 0.25, 1, and 5% sulfur and to monitor the possible toxicity changes related to the nZVI particles before and during the aging period. We used several relevant techniques for monitoring nZVI aging, including transmission electron microscopy, X-ray powder diffraction, and particle size analysis. The toxicity of the nZVI particles was monitored using a new oxidative stress assay based on lipid peroxidation, a simple bacterial cultivation test. A test using activated sludge respiration and phospholipid fatty acid analysis of microbial populations was also employed. The results of the material analyses showed that the sulfidated nZVI particles were more stable than bare nZVI particles in terms of Fe0 content and particle diameter. The stability was more pronounced with the increasing content of sulfur in the nanoparticles; the content of α-Fe was only 35.3% in the nZVI particles compared with 78.6% in the 5% sulfur-doped nanoparticles after 60 days of aging. The results of the oxidative stress assay revealed that the toxicity was also lower with increasing sulfur content; nevertheless, the oxidative stress marker increased substantially after 7 days of aging, reaching a similar level to that caused by bare nZVI in some cases. Other results showed that even incubation in media used for the respective tests caused extensive aging; therefore, this information must be considered before the selection of toxicity assays for nanomaterial evaluation.
P. Skácelová, P. Lebed, J. Filip, D. Oughton and R. Zbořil, "Tracing of iron nanoparticles using an elemental signatures approach: laboratory and field-scale verification," ENVIRONMENTAL SCIENCE: NANO, vol. 7, iss. 2, pp. 623-633, 2020.
DOI: 10.1039/c9en00799g, IF = 8.131
Abstract: Nano-scale zero-valent iron (nZVI) is highly-attractive material that is widely studied and used for pollution abatement, and thus it is one of the most abundant types of engineered nanoparticles introduced into the environment. Nevertheless, there is still a lack of information about the extent of nZVI migration and fate in real groundwater conditions and associated environmental impact and risks related to its introduction into the groundwater/soil. The present paper proposes a new analytical approach based on a multi-elemental signatures (ICP-MS analyses of trace elements in particular nZVI type and soil/groundwater samples) enabling easy tracing of nZVI and their transformation products, as well as their distinguishing from background colloids. A multi-elemental signatures approach was verified under laboratory conditions (in a large-scale sand-filled tank) and subsequently verified at three contaminated sites remediated with nZVI. Multivariate data analysis on 39 elements, such as principle component analysis (PCA), demonstrates that the method can be used to observe changes in signatures over time and it enabled us to confirm the presence of nZVI in monitoring wells. PCA analysis indicated that lanthanides are particularly suitable for tracing nZVI particles.
S. Iravani and R. S. Varma, "Bacteria in Heavy Metal Remediation and Nanoparticle Biosynthesis," ACS SUSTAINABLE CHEMISTRY & ENGINEERING, vol. 8, iss. 14, pp. 5395-5409, 2020.
DOI: 10.1021/acssuschemeng.0c00292, IF = 8.198
Abstract: Biosynthesis of nanomaterials using natural and biological materials as reducing, stabilizing, and capping agents is an important field of biomaterial science, nanoscience, and nanobiotechnology. Relative to conventional approaches for the assembly of nanomaterial deploying hazardous and dangerous resources, bioinspired synthesis using bacteria has significant advantages of cost-effectiveness and eco-friendliness besides being a sustainable, nontoxic, and inexpensive option. Additionally, bacteria can be used for the bioreduction and biorecovery of heavy metal ions. Bacterial cells, as efficient biofactories, have significant ability to bioreduce metal ions that can be obtained as nanocrystals of varying morphologies and sizes. In this regard, bacteria-assisted nanoparticle synthesis and the associated parameters need to be optimized, comprehensively. The developments in nanoparticle biosynthesis domain conform to the green chemistry principles that minimize the use of hazardous materials and maximize the safety and sustainability of the nanoparticle preparation. In this review, important issues pertaining to bioaccumulation, biotransformation, and biosynthesis of metallic nanoparticles using bacteria are highlighted including the mechanistic aspects of the bacterial synthesis of nanoparticles.
G. Jaiswal, V. G. Landge, M. Subaramanian, R. G. Kadam, R. Zbořil, M. B. Gawande and E. Balaraman, "N-Graphitic Modified Cobalt Nanoparticles Supported on Graphene for Tandem Dehydrogenation of Ammonia–Borane and Semihydrogenation of Alkynes," ACS SUSTAINABLE CHEMISTRY & ENGINEERING, vol. 8, iss. 30, pp. 11058-11068, 2020.
DOI: 10.1021/acssuschemeng.9b07211, IF = 8.198
Abstract: The utilization of non-noble metals for the design of advanced catalysts is gaining importance from an environmental sustainability viewpoint. A variety of non-noble metal nanoparticles decorated on electron-rich carbon, which provides active sites for the catalysis, have been extensively studied in recent times. Herein, we report an efficient and reusable N-graphitic modified cobalt nanoparticles supported on graphene for dehydrogenation of ammonia–borane (AB, H3N–BH3), and selective catalytic hydrogenation of alkynes in tandem manner. The catalyst was prepared by a simple procedure on a multigram scale using inexpensive precursors followed by pyrolysis. This stable nanocatalyst performs efficiently with a nine-run recycling test. Furthermore, mechanistic studies clearly show that NH3:BH3 acts as a hydride source and methanol acts as a protic source during the stereoselective hydrogenation reaction. The findings demonstrate the potential for the development of N-graphitic modified metal nanoparticles supported on graphene for the development of new materials with far-reaching implications in catalysis and organic synthesis.
A. Lewalska-Graczyk, P. Pieta, G. Garbarino, G. Busca, M. Holdynski, G. Kalisz, A. Sroka-Bartnicka, R. Nowakowski, M. Naushad, M. B. Gawande, R. Zbořil and I. S.Pieta, "Graphitic Carbon Nitride–Nickel Catalyst: From Material Characterization to Efficient Ethanol Electrooxidation," ACS SUSTAINABLE CHEMISTRY & ENGINEERING, vol. 8, iss. 18, pp. 7244–7255, 2020.
DOI: 10.1021/acssuschemeng.0c02267, IF = 8.198
Abstract: N-doped carbon material, graphitic carbon nitride (gCN), is a semiconductor with high mechanical and thermal stability, which provides good dispersion of metal particles. As it is resistant to corrosion, it constitutes an alternative to carbon black as a catalyst support in polymer electrolyte membrane fuel cells (PEMFCs), e.g. in alcohol oxidation reactions. Due to the fact that its composition (C:N ratio, presence of H atoms) and structural form may vary according to the preparation conditions, a detailed analysis is necessary for their exact determination. In this research work, a detailed characterization of gCN catalyst support by spectroscopic (UV-vis, IR, Raman) and microscopic techniques (SEM, TEM, AFM) was conducted in order to gain deeper understanding of material properties. As a next step, Ni-doped graphitic carbon nitride (Ni/gCN) was tested in electrooxidation of ethanol demonstrating comparatively high peak current density and interesting photocatalytic properties. The obtained results suggest that the improvement of the activity and selectivity of Ni modified gCN can be a promising methodology for low temperature conversion of second-generation biofuels, helping mitigate the CO2 footprint and energy related emissions.
P. Sharma, D. K. Patel, S. Kancharlapalli, S. Magdassi and Y. Sasson, "Facile Combined Experimental and Computational Study: g-C3N4@PDMS-Assisted Knoevenagel Condensation Reaction under Phase Transfer Conditions," ACS SUSTAINABLE CHEMISTRY & ENGINEERING, vol. 8, iss. 6, pp. 2350-2360, 2020.
DOI: 10.1021/acssuschemeng.9b04082, IF = 8.198
Abstract: A new recyclable g-C3N4@PDMS heterogeneous catalyst has been developed as an efficient catalyst with an appreciable reactivity toward Knoevenagel condensation in the presence of crown ether (PTC). Here, a two-dimensional (2D) printed g-C3N4@PDMS heterogeneous catalyst opens the gate of possibility for high mechanical strength with the possibility of an appreciable recyclability. Various performed parameter studies clarify that g-C3N4 active sites exclusively enhance the cinnamic acid synthesis under mild reaction conditions. To explore the molecular mechanism of the condensation reaction over the heterogeneous catalyst surface, a systematic density functional theory-based computational study has been carried out. g-C3N4 material-based model substrate consisting of amine active sites has been considered for modeling the condensation reaction. The reaction energy profile for the condensation reaction between benzaldehyde and para-nitrotoluene on model substrate has been analyzed. The g-C3N4@PDMS catalyst is reused for several runs without loss in reaction rate, evidently due to the g-C3N4 active site being effectively implanted with highly resistant poly(dimethylsiloxane) (PDMS) layer. Recycled g-C3N4@PDMS heterogeneous 2D film characterization studies, viz., X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy, confirm that the active site and molecular structure are well preserved even after multiple reaction cycles. Various reactants were screened using the heterogeneous g-C3N4@PDMS catalyst, exhibiting an appreciable product yield (∼99%) at room temperature in a short reaction time of 30 min.
D. Zaoralová, V. Hrubý, V. Šedajová, R. Mach, V. Kupka, J. Ugolotti, A. Bakandritsos, M. Medved’ and M. Otyepka, "Tunable Synthesis of Nitrogen Doped Graphene from Fluorographene under Mild Conditions," ACS SUSTAINABLE CHEMISTRY & ENGINEERING, vol. 8, iss. 12, pp. 4764-4772, 2020.
DOI: 10.1021/acssuschemeng.9b07161, IF = 8.198
Abstract: The nitrogen doping of graphene via mild and low energy processes to afford homogeneous product composition and topology with high nitrogen content (>10 at. %) remains a challenge of contemporary 2D materials chemistry. Here, we report a previously unexplored route to synthesize N-doped graphene (NG) with exceptionally high N content (up to 18.2 at. %) by reaction of fluorographene (FG) with NaNH2 in N,N-dimethylformamide (at 130 °C) or acetonitrile (at 70 °C). The N content can be tuned by changing the reaction time, temperature, and/or solvent, ranging from 6.6 to 18.2 at. %, mainly in the form of pyridinic and pyrrolic configurations. With thermal annealing, the N content remained constant up to 400 °C but then decreased by ∼50% upon being further annealed to 1000 °C. Density functional theory (DFT) calculations showed that nitrogen incorporation into the carbon lattice mostly occurred at vacancies present in the starting material. We also conducted a thorough rationalization of side-reaction pathways leading to byproducts, which were confirmed by GC-MS analysis. This is the highest yet recorded N content for a wet chemical doping procedure and at such a low temperature of 70 °C. The reported synthetic approach thus offers a sustainable and cost-effective way to prepare NG with a broad tunability window of N content for potential applications related to energy storage and catalysis.
B. Mallada, S. Edalatmanesh, P. Lazar, J. Redondo, A. Gallardo, R. Zbořil, P. Jelínek, M. Švec and B. de la Torre, "Atomic-Scale Charge Distribution Mapping of Single Substitutional p- and n-Type Dopants in Graphene," ACS SUSTAINABLE CHEMISTRY & ENGINEERING, vol. 8, iss. 8, pp. 3437-3444, 2020.
DOI: 10.1021/acssuschemeng.9b07623, IF = 8.198
Abstract: Tuning the chemical properties of graphene by controlled doping is a widely investigated strategy. The effect of a substitutional single dopant on graphene local reactivity is much less explored. To improve the understanding of the role of p- and n-type dopants in graphene’s local chemical activity and quantification of its interaction with single molecules, we report an atomic-scale investigation of single boron (B) and nitrogen (N) dopants in graphene and their interactions with CO molecules by means of atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM) experiments and theoretical calculations. We infer that N/B doping significantly increases/lowers the chemical interaction of graphene with individual CO molecules as a result of weak electrostatic forces induced by distinct charge distribution around the dopant site. High-resolution AFM images allow dopant discrimination and their atomic-scale structural characterization, which may be crucial for the atomic-scale design of graphene derivatives with relevant potential applications in molecular sensing and catalysis.
J. K. Wychowaniec, J. Litowczenko, K. Tadyszak, V. Natu, C. Aparicio, B. Peplińska, M. W. Barsoum, M. Otyepka and B. Scheibe, "Unique cellular network formation guided by heterostructures based on reduced graphene oxide - Ti3C2Tx MXene hydrogels," ACTA BIOMATERIALIA, vol. 115, iss. , pp. 104-115, 2020.
DOI: 10.1016/j.actbio.2020.08.010, IF = 8.947
Abstract: Two-dimensional (2D) materials remain highly interesting for assembling three-dimensional (3D) structures, amongst others, in the form of macroscopic hydrogels. Herein, we present a novel approach for inducing chemical inter-sheet crosslinks via an ethylenediamine mediated reaction between Ti3C2Tx and graphene oxide in order to obtain a reduced graphene oxide-MXene (rGO-MXene) hydrogel. The composite hydrogels are hydrophilic with a stiffness of ~20 kPa. They also possess a unique inter-connected porous architecture, which led to a hitherto unprecedented ability of human cells across three different types, epithelial adenocarcinoma, neuroblastoma and fibroblasts, to form inter-connected three-dimensional networks. The attachments of the cells to the rGO-MXene hydrogels were superior to those of the sole rGO-control gels. This phenomenon stems from the strong affinity of cellular protrusions (neurites, lamellipodia and filopodia) to grow and connect along architectural network paths within the rGO-MXene hydrogel, which could lead to advanced control over macroscopic formations of cellular networks for technologically relevant bioengineering applications, including tissue engineering and personalized diagnostic networks-on-chip.
H. Alamgholiloo, S. Rostamnia, A. Hassankhani, X. Liu, A. Eftekhari, A. Hasanzadeh, K. Zhang, H. Karimi-Maleh, S. Khaksar, R. S. Varma and M. Shokouhimehr, "Formation and stabilization of colloidal ultra-small palladium nanoparticles on diamine-modified Cr-MIL-101: Synergic boost to hydrogen production from formic acid," JOURNAL OF COLLOID AND INTERFACE SCIENCE, vol. 567, pp. 126-135, 2020.
DOI: 10.1016/j.jcis.2020.01.087, IF = 8.128
Abstract: Ultra-small nano-sized palladium particles were successfully stabilized within the pores of diamine groups grafted open metal site metal-organic frameworks of Cr-MIL-101; coordinated diamine groups of ethylene diamine (ED) and propyl diamine (PD) on the active site of chromium units of Cr-MIL-101. The physiochemical properties of the Pd@Cr-MOFs were investigated using FTIR, XRD, SEM/EDX mapping, TEM, BET, and AAS. The Cr-MIL-101 stabilized ultra-small Pd nanoparticles, Pd@(ethylene diamine)/Cr-MIL-101, and Pd@(propyl diamine)/Cr-MIL-101, displayed catalytic activity for clean dehydrogenation of formic acid and generation of hydrogen at room temperature. The resultant Pd@ED/Cr-MIL-101 catalyst indicates high catalytic activity with turnover frequency (TOF) of 583 h−1 at 328 K, which is superior to most of the reported catalysts, including Pd@PD/Cr-MIL-101 with TOF 532 h−1. Our studies open up a new method to the design of an ultra-small metal nanoparticle for the catalytic dehydrogenation of HCOOH.
D. Sen, P. Błoński, B. d. l. Torre, P. Jelínek and M. Otyepka, "Thermally induced intra-molecular transformation and metalation of free-base porphyrin on Au(111) surface steered by surface confinement and ad-atoms," NANOSCALE ADVANCES, vol. 2, iss. 7, pp. 2986-2991, 2020.
DOI: 10.1039/d0na00401d, IF = 4.553
Abstract: We investigated chemical transformations of a fluorinated free-base porphyrin, 5,10,15,20-tetrakis(4-fluorophenyl)-21,23H-porphyrin (2H-4FTPP) under a Au(111) surface confinement and including gold adatoms by using an experiment and density functional theory based first-principles calculations. Annealing of 2H-4FTPP led to cyclodehydrogenation of the molecule to a π-extended fused aromatic planar compound, 2H-4FPP, and metallation of the porphyrin ring by Au atoms to Au-4FPP complex. Noticeable lowering of bond-dissociation energies of the pyrrole's C–H bonds of the Au(111) supported molecule with respect to their values in the gas phase explained the observed on-surface planarization. Our findings also indicate that Au adatoms may catalyze cleavage of C–H/F bonds in temperature-initiated processes on Au surfaces. BDEs and explicit inclusion of Au adatoms helps to rationalize thermally induced chemical reactions on the respective surface.
S. Phetsang, S. Nootchanat, C. Lertvachirapaiboon, R. Ishikawa, K. Shinbo, K. Kato, P. Mungkornasawakul, K. Ounnunkad and A. Baba, "Enhancement of organic solar cell performance by incorporating gold quantum dots (AuQDs) on a plasmonic grating," NANOSCALE ADVANCES, vol. 2, iss. 7, pp. 2950-2957, 2020.
DOI: 10.1039/d0na00169d, IF = 4.553
Abstract: The incorporation of metallic nanoobjects into devices allows to increase light harvesting, which increases the device performance. In this study, we used a combination of gold quantum dots and grating-coupled surface plasmon resonance (GCSPR) to improve the performance of organic solar cells (OSCs) with a poly(3-hexylthiophene-2,5-diyl) (P3HT):[6,6]-phenyl C61 butyric acid methyl ester (PCBM) photoactive layer. Gold quantum dots with a green fluorescent color (green-AuQD) were loaded into a hole transport layer (HTL) aiming to harvest photons in the UV region and emit visible light into the neighboring photoactive layer. Meanwhile, plasmonic grating structures, which were created on the photoactive layer surfaces via the nanoimprinting technique, provided an enhancement effect through light scattering and GCSPR. Thus, an excellent enhancement of OSC efficiency with a significant increase in short circuit photocurrent (JSC) and power conversion efficiency (PCE) in comparison to that of the reference cell was achieved. The fabricated device provides a JSC value as high as 8.41 mA cm−2 (a 14.11% enhancement) and a PCE value of 3.91% (a 19.57% enhancement). The systematic study clearly reveals that the remarkable enhancement of OSC efficiency is achieved by incorporating both AuQD and plasmonic grating.
M. Nasrollahzadeh, M. Sajjadi, S. Iravani and R. S. Varma, "Starch, cellulose, pectin, gum, alginate, chitin and chitosan derived (nano)materials for sustainable water treatment: A review," CARBOHYDRATE POLYMERS, vol. 251, pp. 116986, 2020.
DOI: 10.1016/j.carbpol.2020.116986, IF = 9.381
Abstract: Natural biopolymers, polymeric organic molecules produced by living organisms and/or renewable resources, are considered greener, sustainable, and eco-friendly materials. Natural polysaccharides comprising cellulose, chitin/chitosan, starch, gum, alginate, and pectin are sustainable materials owing to their outstanding structural features, abundant availability, and nontoxicity, ease of modification, biocompatibility, and promissing potentials. Plentiful polysaccharides have been utilized for making assorted (nano)catalysts in recent years; fabrication of polysaccharides-supported metal/metal oxide (nano)materials is one of the effective strategies in nanotechnology. Water is one of the world's foremost environmental stress concerns. Nanomaterial-adorned polysaccharides-based entities have functioned as novel and more efficient (nano)catalysts or sorbents in eliminating an array of aqueous pollutants and contaminants, including ionic metals and organic/inorganic pollutants from wastewater. This review encompasses recent advancements, trends and challenges for natural biopolymers assembled from renewable resources for exploitation in the production of starch, cellulose, pectin, gum, alginate, chitin and chitosan-derived (nano)materials.
D. Silvestri, S. Wacławek, A. Venkateshaiah, K. Krawczyk, B. Sobel, V. V. Padil, M. Černík and R. S. Varma, "Synthesis of Ag nanoparticles by a chitosan-poly(3-hydroxybutyrate) polymer conjugate and their superb catalytic activity," CARBOHYDRATE POLYMERS, vol. 232, p. 115806, 2020.
DOI: 10.1016/j.carbpol.2019.115806, IF = 9.381
Abstract: This work describes an eco-friendly and sustainable technique for the synthesis of silver nanoparticles (nAg), where chitosan-poly(3-hydroxybutyrate) polymer conjugate (Chit-PHB) acts as a reducing and stabilizing material. The ensuing nanoparticles show an exceptional catalytic activity in the reduction of 4-nitrophenol to 4-aminophenol. nAg were characterized by several techniques, i.e. SEM and TEM-EDX, to confirm their production, size and morphology. Furthermore, infrared spectroscopy analysis proved the presence of a Chit-PHB coating on the nAg. The excellent catalytic properties of the nAg-Chit-PHB was discernible when the activity parameter (κc) normalized by the specific surface area (SSA) of the nanoparticles was taken into consideration; normalization of κc by the SSA is a vital parameter for the assessment of the accessibility to the surface area of particles. Herein synthesized Ag nanoparticles, as far as we know, exhibited the fastest reaction kinetics of 4-nitrophenol reduction compared to the silver nanoparticles reported in the literature.
M. Šimek, K. Lemr, M. Hermannová and V. Havlíček, "Analysis of hyaluronan and its derivatives using chromatographic and mass spectrometric techniques," CARBOHYDRATE POLYMERS, vol. 250, pp. 117014, 2020.
DOI: 10.1016/j.carbpol.2020.117014, IF = 9.381
Abstract: The aim of this paper is to review chromatographic and mass-spectrometric methods and underline the best analytical approaches for successful analysis of various hyaluronic acid species in different types of samples. Hyaluronan-degrading enzymes and chemical depolymerization produce di- or oligosaccharides suitable for hyaluronan quantification or structural characterization of hyaluronan derivatives. Efficient purification and pre-column derivatization of hyaluronan disaccharides by reductive amination allow subnanogram quantification in biological samples. The chromatographic separation is capable to distinguish all glycosaminoglycans disaccharides and to resolve hyaluronan fragments with 2−40 monomers. Using electrospray ionization or matrix assisted laser desorption ionization, hyaluronan fragments up to 8 kDa or 41 kDa, respectively, can be observed. One- or two-dimensional chromatographic separation with higly sensitive mass-spectrometric detection is an indispensable tool for revealing substituent position, extent of modification and substitution patterns of chemically modified hyaluronan derivatives. It is essential for studying structure‐biological function relationships of hyaluronan and its derivatives.
V. V. Padil, J. Y. Cheong, A. KP, P. Makvandi, E. N. Zare, R. Torres-Mendieta, S. Wacławek, M. Černík, I. Kim and R. S. Varma, "Electrospun fibers based on carbohydrate gum polymers and their multifaceted applications," CARBOHYDRATE POLYMERS, vol. 247, pp. 116705, 2020.
DOI: 10.1016/j.carbpol.2020.116705, IF = 9.381
Abstract: Electrospinning has garnered significant attention in view of its many advantages such as feasibility for various polymers, scalability required for mass production, and ease of processing. Extensive studies have been devoted to the use of electrospinning to fabricate various electrospun nanofibers derived from carbohydrate gum polymers in combination with synthetic polymers and/or additives of inorganic or organic materials with gums. In view of the versatility and the widespread choice of precursors that can be deployed for electrospinning, various gums from both, the plants and microbial-based gum carbohydrates are holistically and/or partially included in the electrospinning solution for the preparation of functional composite nanofibers. Moreover, our strategy encompasses a combination of natural gums with other polymers/inorganic or nanoparticles to ensue distinct properties. This early established milestone in functional carbohydrate gum polymer-based composite nanofibers may be deployed by specialized researchers in the field of nanoscience and technology, and especially for exploiting electrospinning of natural gums composites for diverse applications.
N. Motahharifar, M. Nasrollahzadeh, A. Taheri-Kafrani, R. S. Varma and M. Shokouhimehr, "Magnetic chitosan-copper nanocomposite: A plant assembled catalyst for the synthesis of amino- and N-sulfonyl tetrazoles in eco-friendly media," CARBOHYDRATE POLYMERS, vol. 232, p. 115819, 2020.
DOI: 10.1016/j.carbpol.2019.115819, IF = 9.381
Abstract: A greener, cost efficient and simple method is described to prepare copper nanoparticles (NPs) immobilized on the magnetic chitosan (one of the more versatile polysaccharides) using Euphorbia falcata leaf extract as reducing/stabilizing agent. The prepared catalyst (Cu NPs@Fe3O4-chitosan) was authenticated by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), Scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDS), thermogravimetry/derivative thermogravimetry (TG/DTG), Vibrating sample magnetometer (VSM), and elemental mapping. TEM analysis indicates that Cu NPs with average sizes in 5−10 nm range is formed on magnetic chitosan with the spherical morphology. The Cu NPs@Fe3O4-chitosan was employed as a new catalyst for the synthesis of different tetrazoles by the reaction of various secondary or tertiary cyanamides with sodium azide in water under reflux conditions. Easy separation by external magnetic field, mild reaction conditions, low cost and the reusability are some of the beneficial features of this catalyst.
J. Martincová, M. Otyepka and P. Lazar, "Oxidation of metallic two-dimensional transition metal dichalcogenides: 1T-MoS2 and 1T-TaS2," 2D MATERIALS, vol. 7, iss. 4, pp. 045005, 2020.
DOI: 10.1088/2053-1583/ab9dd4, IF = 7.103
Abstract: Molybdenum disulphide (MoS2) and tantalum disulphide (TaS2) are well-known members of the transition metal dichalcogenide (TMD) family. They occur naturally in hexagonal (2H) forms but can also be synthesized in metallic trigonal (1T) phases that are active hydrogen evolution catalysts and exhibit interesting phenomena such as superconductivity and charge density waves. Sparse experimental evidence indicates that 2D crystals of metallic TMDs degrade rapidly in air via an unknown oxidation mechanism. Here we present a computational study on oxidation at the edges and surfaces of 1T-MoS2 and 1T-TaS2 monolayers based on density functional theory calculations. Our results suggest that both 1T-MoS2 and 1T-TaS2 are very susceptible to oxidation because there are negligible energetic barriers to the dissociation of oxygen molecules at edge sites. However, further oxidation requires the substitution of sulphur atoms by oxygen, the rate of which is limited in the case of 1T-TaS2 because the detachment of SO2 groups is disfavored by 1.2 eV. Conversely, oxygen molecules adsorbed on 1T-MoS2 dissociate directly at molybdenum atoms at the edge, forming intermediate S-O-Mo structures that facilitate the subsequent formation and detachment of SO2. Oxidation is not harmful to the catalysis of the hydrogen evolution reaction on 1T-MoS2 but is detrimental to that on 1T-TaS2, which explains some apparently inconsistent experimental results. These results provide new insights into the mechanism of ambient oxidative degradation of metallic TMDs and the effect of oxidation on their catalytic properties.
V. Kachwal, P. K. Sharma, A. Sarmah, S. Chowdhury and I. R. Laskar, "A multistimuli responsive heteroleptic iridium(iii) complex: role of hydrogen bonding in probing solvent, pH and bovine serum albumin (BSA)," JOURNAL OF MATERIALS CHEMISTRY C, vol. 8, iss. 19, pp. 6605-6614, 2020.
DOI: 10.1039/c9tc07050h, IF = 7.393
Abstract: This article focuses on the vital role of hydrogen bonding to explain some unusual photophysical behaviors of an ‘Aggregation-induced emission’ (AIE) active Iridium(III) complex. The preponderance of hydrogen bonding leads to the complex's multifunctional character, viz., sensing ability of base and protein (BSA), pH probing, and solvatochromism. Depending on the hydrogen bonding capacity of the solvents, the emission properties of the complex are changed, i.e., green emission in non-polar solvents, yellowish-green emission in a chlorinated solvent, bright yellow emission in a polar aprotic solvent and weak yellow emission in polar protic solvent. A robust green emission was obtained with the addition of BSA into a solution of 1. The sensitivity of the complex to BSA was measured to be 9.3 pM. The mechanisms in all these cases have been explored based on control experiments and computational calculations/studies (DFT, TD-DFT, Docking).
S. Kalytchuk, L. Zdražil, M. Scheibe and R. Zboril, "Purple-emissive carbon dots enhance sensitivity of Si photodetectors to ultraviolet range," NANOSCALE, vol. 12, iss. 15, pp. 8379–8384, 2020.
DOI: 10.1039/d0nr00505c, IF = 7.790
Abstract: In this work, we realized the synthesis of purple-emissive carbon dots (p-CDs) by a facile and highly reproducible route using folic acid as a sole precursor. The emission of the p-CDs is located around 390 nm, and independent of the excitation wavelength with a high photoluminescence quantum yield of 54.6%, thus complementing an emission color palette of brightly emitting carbon dots to a purple. Purple-emissive CDs are highly stable in both the colloidal state and in polymer films. A carbon dot luminescence down-shifting layer is used to sensitize a Si photodetector to UV range. As an example, p-CDs with an excitation maximum at 330 nm were integrated into Si photodetector, resulting in improving the photoresponsivity in a UV range from 0.8 to 2.5 mA/W, with a relative enhancement of 203.8%. This work represents a cheap, scalable and environmentally friendly way to create purple-emissive carbon dots enhancing the photoresponsivity of commercial photodetectors in a UV range thus being applicable in optical power meters, optical wireless communication systems, sunlight sensors, spectrophotometers, or radiation detectors.
L. Zdražil, S. Kalytchuk, K. Holá, M. Petr, O. Zmeškal, Š. Kment, A. Rogach and R. Zbořil, "Carbon dot-based tandem luminescent solar concentrator," NANOSCALE, vol. 12, iss. 12, pp. 6664-6672, 2020.
DOI: 10.1039/c9nr10029f, IF = 7.790
Abstract: Luminescent solar concentrators (LSCs) are light-management devices, which are used for harvesting and concentrating of solar light from a large area to their edges. Being semitransparent devices, LSCs keep a great promise for future utilization in glass walls of urban buildings as environmentally friendly photovoltaic power plants. Development of cheap and eco-safe materials, extension of the LSC operation range as well as the enhancement of the optical efficiency are the key challenges, which need to be solved in order to transform energetically passive buildings into self-sustainable units. Here, a large area (64 cm2) tandem LSC fabricated from entirely eco-friendly highly emissive blue, green, and red carbon dots is demonstrated, with an internal optical quantum efficiency of 23.6% and an external optical quantum efficiency of 2.3%, while maintaining a high transparency across the visible spectrum. This opens up a new direction for application of carbon dots for advanced solar light harvesting technologies.
M. Langer, M. Paloncýová, M. Medved’ and M. Otyepka, "Molecular Fluorophores Self-Organize into C-Dot Seeds and Incorporate into C-Dot Structures," THE JOURNAL OF PHYSICAL CHEMISTRY LETTERS, vol. 11, iss. 19, pp. 8252-8258, 2020.
DOI: 10.1021/acs.jpclett.0c01873, IF = 6.475
Abstract: Various molecular fluorophores have been identified to be present during carbon-dot (C-dot) syntheses. However, the organization of such fluorophores in C-dots is still unknown. We study the self-assembly of 5-oxo-1,2,3,5-tetrahydroimidazo-[1,2-α]-pyridine-7-carboxylic acid (IPCA), a molecular fluorophore present during the synthesis of C-dots from citric acid and ethylenediamine. Both forms of IPCA (neutral and anionic) show a tendency to self-assemble into stacked systems, forming seeds of C-dots during their synthesis. IPCA also interacts with graphitic C-dot building blocks, fragments easily, and incorporates into their structures via π–π stacking. Both IPCA forms are able to create adlayers internally stabilized by an extensive hydrogen bonding network, with an arrangement of layers similar to that in ordinary graphitic C-dots. The results show the tendency of molecular fluorophores to form organized stacked seeds of C-dots and incorporate into C-dot structures. Such noncovalent structures can be further covalently interlinked via the carbonization process during C-dot growth.
S. Molinari, M. Magro, D. Baratella, G. Salviulo, J. Ugolotti, J. Filip, M. Petr, J. Tucek, G. Zoppellaro, R. Zboril and F. Vianello, "Smart synthetic maghemite nanoparticles with unique surface properties encode binding specificity toward AsIII," SCIENCE OF THE TOTAL ENVIRONMENT, vol. 741, pp. 140175, 2020.
DOI: 10.1016/j.scitotenv.2020.140175, IF = 7.963
Abstract: Pristine ɣ-Fe2O3 nanoparticles, called surface active maghemite nanoparticles (SAMNs) display unprecedented colloidal stability and specific binding properties. Herein, the interactions of SAMNs with AsV and AsIII as surface molecular probes were comparatively studied. Thermodynamic and kinetic characterizations, along with chemical and structural analysis of SAMN@As complexes, evidenced two distinct binding modalities. Arsenite, emerged as an elective and specific ligand for SAMNs, whereas arsenate adsorption was more labile, pH dependent and ruled by different binding possibilities. In particular, AsIII oxyacid exclusively interacts through inner-sphere coordination occupying available surface crystal positions resembling a key-lock fitting, while AsV leads to both outer-sphere and inner-sphere complexes. Noteworthy, discrimination between AsV and AsIII was never reported for nanostructured maghemite evidencing the importance of synthetic route on surface properties of the nanomaterial. The present report, besides enriching the chemistry of nanosized iron oxides, suggests SAMNs application for the remediation of water contaminated by AsIII, the most threatening As species in water.
J. Gajdár, K. Tsami, H. Michnová, T. Goněc, M. Brázdová, Z. Soldánová, M. Fojta, J. Jampílek, J. Barek and J. Fischer, "Electrochemistry of ring-substituted 1-hydroxynaphthalene-2-carboxanilides: Relation to structure and biological activity," ELECTROCHIMICA ACTA, vol. 332, p. 135485, 2020.
DOI: 10.1016/j.electacta.2019.135485, IF = 6.901
Abstract: Twenty-two novel antimycobacterial agents, 1-hydroxynaphthalene-2-carboxanilides, were studied by cyclic voltammetry on a glassy carbon electrode in a phosphate buffer pH 7.2 – dimethyl sulfoxide (DMSO) mixed medium (9:1; v/v). All compounds exhibited similar voltammetric behavior with one irreversible anodic signal in the range 100–300 mV corresponding to the oxidation of hydroxyl group on the naphthalene moiety. A shift of the oxidation potential was caused solely by electron donating or withdrawing effects of substituents and their position on the benzene moiety. Mechanism of oxidation in the studied medium was briefly outlined. Values of oxidation potentials exhibited very good linear correlation with calculated Hammett σ substituent constants. For all active compounds, a relationship between oxidation potentials and MIC or IC50 values obtained from in vitro screening was investigated in detail. Primary in vitro screening of synthesized compounds was previously performed against three species of Mycobacterium pathogens. Additionally, their activity related to the inhibition of photosynthetic electron transport (PET) in spinach chloroplasts was tested in previous publications. In vitro screening against Mycobacterium tuberculosis was performed here for the first time with 1-hydroxy-N-(3-trifluoromethylphenyl)naphthalene-2-carboxamide being the most effective (MIC = 11.7 μmol L−1). Furthermore, several other compounds showed higher antimycobacterial activity than the standard isoniazid. Relation of biological activities and oxidation potentials was successfully found in some cases; however, final correlations must also be considered with other physical and chemical factors contributing to the biological activity. Relation of structure, biological activity and electrochemical potential was also studied by cyclic voltammetry in cathodic area for three compounds containing reducible nitro moiety.
M. Magro, S. Molinari, A. Venerando, D. Baratella, G. Zoppellaro, G. Salviulo, R. Zboril and F. Vianello, "Colloidal maghemite nanoparticles with oxyhydroxide-like interface and chiroptical properties," APPLIED SURFACE SCIENCE, vol. 534, pp. 147567, 2020.
DOI: 10.1016/j.apsusc.2020.147567, IF = 6.707
Abstract: Magnetic nanoparticles, mainly constituted of magnetite and maghemite, are widely used for environmental, biomedical and biotechnological applications. Herein, the synthesis and properties of maghemite nanoparticles characterized by chiroptical activity, representing an unprecedented feature for iron oxide nanoparticles, is described in detail. Among nanosized iron oxides, these maghemite nanoparticles stand out for the excellent colloidal stability in water and the witnessed ability to specifically bind selected molecules. The surface properties of nanoparticles were probed with AsIII and AsV oxyacids, studied by x-ray photoelectron spectroscopy and correlated to circular dichroism. The dichroic signal of nanoparticles was differently influenced by the coordination of ligands. Crystalline vacancies on the nanomaterial surface were identified as the chiral centers responsible of the dichroic behavior and the selectivity toward ligands. The latter was correlated with the ability of restructuring the nanomaterial at the crystal truncation. Furthermore, surface binding sites emerged for bearing labile coordination water in analogy with iron oxyhydroxides. The present report, besides enriching the colloidal chemistry of iron oxide based nanomaterials, can stimulate further research on inorganic systems expressing intrinsic chiral properties.
M. Nasrollahzadeh, N. Shafiei, Z. Nezafat, N. Sadat Soheili Bidgoli, F. Soleimani and R. S. Varma, "Valorisation of Fruits, their Juices and Residues into Valuable (Nano)materials for Applications in Chemical Catalysis and Environment," THE CHEMICAL RECORD, vol. 20, iss. 11, pp. 1338-1393, 2020.
DOI: 10.1002/tcr.202000078, IF = 6.771
Abstract: One of the most abundant wastes from all around the world is nutrient resources. Among them, fruits, their extracts, and residues comprise a major portion, which contain many valuable components that get lost during disposal or become burden on the shrinking landfills. These concerns are addressed by seeking sustainable processing methods that would have a minimal environmental impact. The crops contain renewable chemicals which are useful for catalysis, wastewater treatment, or preparation of nanomaterials; there has been an upsurge for the industrial applications of (nano)materials as their environmental and catalytic appliances is a fascinating subject to design cheaper and safer catalytic systems. Due to the excellent chemical properties of the fruit extracts, they have garnered attention as cost‐effective catalysts and support materials. This review focuses on the preparation of (nano)materials and their catalytic and environmental applications and highlights the potential appliances and industrial benefits derived from these low‐cost renewable and sustainable greener sources thus essentially converting waste into wealth.
K. E. Szkaradek, P. Stadlbauer, J. Šponer, R. W. Góra and R. Szabla, "UV-induced hydrogen transfer in DNA base pairs promoted by dark nπ* states," CHEMICAL COMMUNICATIONS, vol. 56, iss. 2, pp. 201-204, 2020.
DOI: 10.1039/c9cc06180k, IF = 6.222
Abstract: Dark nπ* states were shown to have substantial contribution to the destructive photochemistry of pyrimidine nucleobases. Based on quantum-chemical calculations, we demonstrate that the characteristic hydrogen bonding pattern of the GC base pair could facilitate the formation of a wobble excited-state charge-transfer Image ID:c9cc06180k-t1.gif complex. This entails a barrierless electron-driven proton transfer (EDPT) process which enables damageless photodeactivation of the base pair. These photostabilizing properties are retained even when guanine is exchanged to hypoxanthine. The inaccessibility of this process in the AT base pair sheds further light on the reasons why cytosine is less susceptible to the formation of photodimers in double-stranded DNA.
D. D. Chronopoulos, M. Medveď, G. Potsi, O. Tomanec, M. Scheibe and M. Otyepka, "Tunable one-step double functionalization of graphene based on fluorographene chemistry," CHEMICAL COMMUNICATIONS, vol. 56, iss. 13, pp. 1936-1939, 2020.
DOI: 10.1039/c9cc09514d, IF = 6.222
Abstract: Double functionalized graphene derivatives were synthetized by a one-pot reaction of fluorographene with organometallic nucleophiles. Their nucleophilicity governed the preference for grafting and was utilized for tuning the functionalization. This approach paves the way toward the facile, up-scalable and controllable multifunctionalization of graphene.
S. Iravani and R. S. Varma, "Green synthesis, biomedical and biotechnological applications of carbon and graphene quantum dots. A review," ENVIRONMENTAL CHEMISTRY LETTERS, vol. 18, iss. 3, pp. 703-727, 2020.
DOI: 10.1007/s10311-020-00984-0, IF = 9.027
Abstract: Carbon and graphene quantum dots are prepared using top-down and bottom-up methods. Sustainable synthesis of quantum dots has several advantages such as the use of low-cost and non-toxic raw materials, simple operations, expeditious reactions, renewable resources and straightforward post-processing steps. These nanomaterials are promising for clinical and biomedical sciences, especially in bioimaging, diagnosis, bioanalytical assays and biosensors. Here we review green methods for the fabrication of quantum dots, and biomedical and biotechnological applications.
V. Srivastava, E. N. Zare, P. Makvandi, X. Zheng, S. Iftekhar, A. Wu, V. V. Padil, B. Mokhtari, R. S. Varma, F. R. Tay and M. Sillanpaa, "Cytotoxic aquatic pollutants and their removal by nanocomposite-based sorbents," CHEMOSPHERE, vol. 258, p. 127324, 2020.
DOI: 10.1016/j.chemosphere.2020.127324, IF = 7.086
Abstract: Water is an extremely essential compound for human life and, hence, accessing drinking water is very important all over the world. Nowadays, due to the urbanization and industrialization, several noxious pollutants are discharged into water. Water pollution by various cytotoxic contaminants, e.g. heavy metal ions, drugs, pesticides, dyes, residues a drastic public health issue for human beings; hence, this topic has been receiving much attention for the specific approaches and technologies to remove hazardous contaminants from water and wastewater. In the current review, the cytotoxicity of different sorts of aquatic pollutants for mammalian is presented. In addition, we will overview the recent advances in various nanocomposite-based adsorbents and different approaches of pollutants removal from water/wastewater with several examples to provide a backdrop for future research.
S. Aslam, R. U. R. Sagar, H. Kumar, G. Zhang, F. Nosheen, M. Namvari, N. Mahmood, M. Zhang and Y. Qiu, "Mixed-dimensional heterostructures of hydrophobic/hydrophilic graphene foam for tunable hydrogen evolution reaction," CHEMOSPHERE, vol. 245, p. 125607, 2020.
DOI: 10.1016/j.chemosphere.2019.125607, IF = 7.086
Abstract: The synergetic effect of hydrophilic and hydrophobic carbon can be used to obtain tunable hydrogen evolution reaction (HER) at the interface. Herein, graphene oxide (GO-Hummers method) was coated on graphene foam (GF) synthesized via chemical vapor deposition to develop mixed-dimensional heterostructure for the observation of HER. The porosity of GF not only provides an optimized diffusion coefficient for better mass transport but also modified surface chemistry (GF/GO-hydrophobic/hydrophilic interface), which results in an onset potential 50 mV and overpotential of 450 mV to achieve the current density 10 mA/cm2. The surface analysis shows that inherent functional groups at the surface played a key role in tuning the activity of hybrid, providing a pathway to introduce non-corrosive electrodes for water splitting.
O. Ženata, A. Vrzalová, P. Bachleda, J. Janečková, A. Panáček, L. Kvítek and R. Vrzal, "The effect of graphene oxide on signalling of xenobiotic receptors involved in biotransformation," CHEMOSPHERE, vol. 253, pp. 126753, 2020.
DOI: 10.1016/j.chemosphere.2020.126753, IF = 7.086
Abstract: Graphene oxide (GO) is an engineered nanomaterial which was demonstrated to have outstanding capacity for adsorption of organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), the ligands and activators of the aryl hydrocarbon receptor (AhR). Due to the partially overlapping ligand capacity of AhR and pregnane X receptor (PXR), we tested the impact of GO particles on their signalling. While reporter gene assay revealed potentiating effect of GO on ligand-activated AhR-dependent luciferase activity, there was no effect for PXR. However, inducible target genes for AhR (CYP1A1) or PXR (ABCB1) were decreased at mRNA as well as protein levels by the presence of GO in HepG2 (for AhR), LS180 (for PXR) or primary human hepatocytes (both receptors). Moreover, the presence of GO diminished PXR and AhR protein levels in primary cultures of human hepatocytes. This was partially reversed by proteasome inhibitor MG132 for AhR but not for PXR. In conclusion, GO decreases ligand-stimulated activities of AhR and PXR in human cells.
B. Jaleh, S. Karami, M. Sajjadi, B. Feizi Mohazzab, S. Azizian, M. Nasrollahzadeh and R. S. Varma, "Laser-assisted preparation of Pd nanoparticles on carbon cloth for the degradation of environmental pollutants in aqueous medium," CHEMOSPHERE, vol. 246, p. 125755, 2020.
DOI: 10.1016/j.chemosphere.2019.125755, IF = 7.086
Abstract: Laser ablation in liquid (LAL), one of the attractive methods for fabrication of nanoparticles, was used for the modification of carbon cloth (CC) by deposition of palladium nanoparticles (Pd NPs); a simple stirring method was deployed to deposit Pd NPs on the CC surface. Characterization techniques viz X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscope (SEM), energy-dispersive X-ray spectrometry (EDS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) were applied to study the surface of the ensuing samples which confirmed that LAL technique managed to fabricate and deposit the Pd NPs on the surface of CC. In addition, the catalytic prowess of the carbon cloth-Pd NPs (CC/Pd NPs) was investigated in the NaBH4- or HCOOH-assisted reduction of assorted environmental pollutants in aqueous medium namely hexavalent chromium [Cr(VI)], 4-nitrophenol (4-NP), congo red (CR) and methylene blue (MB). The CC/Pd NPs system has advantages such as high stability/sustainability, high catalytic performance and easy reusability.
V. Šlachtová, M. Šebela, E. Torfs, L. Oorts, D. Cappoen, K. Berka, V. Bazgier and L. Brulíková, "Novel thiazolidinedione-hydroxamates as inhibitors of Mycobacterium tuberculosis virulence factor Zmp1," EUROPEAN JOURNAL OF MEDICINAL CHEMISTRY, vol. 185, p. 111812, 2020.
DOI: 10.1016/j.ejmech.2019.111812, IF = 6.514
Abstract: Zinc metalloprotease 1 (Zmp1) is an extracellular enzyme, which has been found essential for the intracellular survival and pathogenesis of Mycobacterium tuberculosis. In this work, we designed and synthesized a series of novel thiazolidinedione-hydroxamates and evaluated in silico their drug-likeness behavior. Then, their inhibitory properties towards a recombinant Zmp1 from Mycobacterium tuberculosis were analyzed by MALDI-TOF MS. Nine of the tested compounds were found to inhibit the enzymatic reaction more effectively than the generic metalloprotease inhibitor phosphoramidon. Furthermore, the synthesized thiazolidinedione-hydroxamate hybrids were evaluated for their in vitro antimycobacterial activity and acute cytotoxicity using whole-cell assays. Results showed that none of the hybrids exhibited acute cytotoxicity against RAW264.7 macrophages. Whereas extracellular antimycobacterial activity was limited, RAW264.7 macrophage infection results showed that a majority of the hybrids inhibited the intracellular growth of Mycobacterium tuberculosis at a concentration of 100 and 10 μM. The thiazolidinedione-hydroxamate compound 2n was considered to be the best candidate of the evaluated library.
B. Islam, P. Stadlbauer, M. Vorlíčková, J. Mergny, M. Otyepka and J. Šponer, "Stability of Two-Quartet G-Quadruplexes and Their Dimers in Atomistic Simulations," JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 16, iss. 6, pp. 3447-3463, 2020.
DOI: 10.1021/acs.jctc.9b01068, IF = 6.006
Abstract: Determination of RNA structural-dynamic properties is challenging for experimental methods. Thus, atomistic molecular dynamics (MD) simulations represent a helpful technique complementary to experiments. However, contemporary MD methods still suffer from limitations of force fields (ffs), including imbalances in the nonbonded ff terms. We have recently demonstrated that some improvement of state-of-the-art AMBER RNA ff can be achieved by adding a new term for H-bonding called gHBfix, which increases tuning flexibility and reduces risk of side-effects. Still, the first gHBfix version did not fully correct simulations of short RNA tetranucleotides (TNs). TNs are key benchmark systems due to availability of unique NMR data, although giving too much weight on improving TN simulations can easily lead to overfitting to A-form RNA. Here we combine the gHBfix version with another term called tHBfix, which separately treats H-bond interactions formed by terminal nucleotides. This allows to refine simulations of RNA TNs without affecting simulations of other RNAs. The approach is in line with adopted strategy of current RNA ffs, where the terminal nucleotides possess different parameters for terminal atoms than the internal nucleotides. Combination of gHBfix with tHBfix significantly improves the behavior of RNA TNs during well-converged enhanced-sampling simulations using replica exchange with solute tempering. TNs mostly populate canonical A-form like states while spurious intercalated structures are largely suppressed. Still, simulations of r(AAAA) and r(UUUU) TNs show some residual discrepancies with primary NMR data which suggests that future tuning of some other ff terms might be useful. Nevertheless, the tHBfix has a clear potential to improve modeling of key biochemical processes, where interactions of RNA single stranded ends are involved.
V. Mlýnský, P. Kührová, T. Kühr, M. Otyepka, G. Bussi, P. Banáš and J. Šponer, "Fine-Tuning of the AMBER RNA Force Field with a New Term Adjusting Interactions of Terminal Nucleotides," JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 16, iss. 6, pp. 3936-3946, 2020.
DOI: 10.1021/acs.jctc.0c00228, IF = 6.006
Abstract: Determination of RNA structural-dynamic properties is challenging for experimental methods. Thus, atomistic molecular dynamics (MD) simulations represent a helpful technique complementary to experiments. However, contemporary MD methods still suffer from limitations of force fields (ffs), including imbalances in the nonbonded ff terms. We have recently demonstrated that some improvement of state-of-the-art AMBER RNA ff can be achieved by adding a new term for H-bonding called gHBfix, which increases tuning flexibility and reduces risk of side-effects. Still, the first gHBfix version did not fully correct simulations of short RNA tetranucleotides (TNs). TNs are key benchmark systems due to availability of unique NMR data, although giving too much weight on improving TN simulations can easily lead to overfitting to A-form RNA. Here we combine the gHBfix version with another term called tHBfix, which separately treats H-bond interactions formed by terminal nucleotides. This allows to refine simulations of RNA TNs without affecting simulations of other RNAs. The approach is in line with adopted strategy of current RNA ffs, where the terminal nucleotides possess different parameters for terminal atoms than the internal nucleotides. Combination of gHBfix with tHBfix significantly improves the behavior of RNA TNs during well-converged enhanced-sampling simulations using replica exchange with solute tempering. TNs mostly populate canonical A-form like states while spurious intercalated structures are largely suppressed. Still, simulations of r(AAAA) and r(UUUU) TNs show some residual discrepancies with primary NMR data which suggests that future tuning of some other ff terms might be useful. Nevertheless, the tHBfix has a clear potential to improve modeling of key biochemical processes, where interactions of RNA single stranded ends are involved.