V. G. Chandrashekhar, T. Senthamarai, R. G. Kadam, O. Malina, J. Kašlík, R. Zbořil, M. B. Gawande, R. V. Jagadeesh and M. Beller, "Silica-supported Fe/Fe–O nanoparticles for the catalytic hydrogenation of nitriles to amines in the presence of aluminium additives," NATURE CATALYSIS, vol. 5, iss. 1, pp. 20-29, 2022.
DOI: 10.1038/s41929-021-00722-x, IF = 41.813
Abstract: The hydrogenation of nitriles to amines represents an important and frequently used industrial process due to the broad applicability of the resulting products in chemistry and life sciences. Despite the existing portfolio of catalysts reported for the hydrogenation of nitriles, the development of iron-based heterogeneous catalysts for this process is still a challenge. Here, we show that the impregnation and pyrolysis of iron(II) acetate on commercial silica produces a reusable Fe/Fe–O@SiO2 catalyst with a well-defined structure comprising the fayalite phase at the Si–Fe interface and α-Fe nanoparticles, covered by an ultrathin amorphous iron(III) oxide layer, growing from the silica matrix. These Fe/Fe–O core–shell nanoparticles, in the presence of catalytic amounts of aluminium additives, promote the hydrogenation of all kinds of nitriles, including structurally challenging and functionally diverse aromatic, heterocyclic, aliphatic and fatty nitriles, to produce primary amines under scalable and industrially viable conditions.
V. Šedajová, A. Bakandritsos, P. Błoński, M. Medveď, R. Langer, D. Zaoralová, J. Ugolotti, J. Dzíbelová, P. Jakubec, V. Kupka and M. Otyepka, "Nitrogen doped graphene with diamond-like bonds achieves unprecedented energy density at high power in a symmetric sustainable supercapacitor," ENERGY & ENVIRONMENTAL SCIENCE, vol. 15, iss. 2, pp. 740-748, 2022.
DOI: 10.1039/d1ee02234b, IF = 38.532
Abstract: Supercapacitors have attracted great interest because of their fast, reversible operation and sustainability. However, their energy densities remain lower than those of batteries. In the last decade, supercapacitors with an energy content of ∼110 W h L−1 at a power of ∼1 kW L−1 were developed by leveraging the open framework structure of graphene-related architectures. Here, we report that the reaction of fluorographene with azide anions enables the preparation of a material combining graphene-type sp2 layers with tetrahedral carbon–carbon bonds and nitrogen (pyridinic and pyrrolic) superdoping (16%). Theoretical investigations showed that the C–C bonds develop between carbon-centered radicals, which emerge in the vicinity of the nitrogen dopants. This material, with diamond-like bonds and an ultra-high mass density of 2.8 g cm−3, is an excellent host for the ions, delivering unprecedented energy densities of 200 W h L−1 at a power of 2.6 kW L−1 and 143 W h L−1 at 52 kW L−1. These findings open a route to materials whose properties may enable a transformative improvement in the performance of supercapacitor components.
A. Cheruvathoor Poulose, G. Zoppellaro, I. Konidakis, E. Serpetzoglou, E. Stratakis, O. Tomanec, M. Beller, A. Bakandritsos and R. Zbořil, "Fast and selective reduction of nitroarenes under visible light with an earth-abundant plasmonic photocatalyst," NATURE NANOTECHNOLOGY, vol. 17, iss. 5, pp. 485-492, 2022.
DOI: 10.1038/s41565-022-01087-3, IF = 39.213
Abstract: Reduction of nitroaromatics to the corresponding amines is a key process in the fine and bulk chemicals industry to produce polymers, pharmaceuticals, agrochemicals and dyes. However, their effective and selective reduction requires high temperatures and pressurized hydrogen and involves noble metal-based catalysts. Here we report on an earth-abundant, plasmonic nano-photocatalyst, with an excellent reaction rate towards the selective hydrogenation of nitroaromatics. With solar light as the only energy input, the chalcopyrite catalyst operates through the combined action of hot holes and photothermal effects. Ultrafast laser transient absorption and light-induced electron paramagnetic resonance spectroscopies have unveiled the energy matching of the hot holes in the valence band of the catalyst with the frontier orbitals of the hydrogen and electron donor, via a transient coordination intermediate. Consequently, the reusable and sustainable copper-iron-sulfide (CuFeS2) catalyst delivers previously unattainable turnover frequencies, even in large-scale reactions, while the cost-normalized production rate stands an order of magnitude above the state of the art.
I. Obraztsov, A. Bakandritsos, V. Šedajová, R. Langer, P. Jakubec, G. Zoppellaro, M. Pykal, V. Presser, M. Otyepka and R. Zbořil, "Graphene Acid for Lithium‐Ion Batteries—Carboxylation Boosts Storage Capacity in Graphene," ADVANCED ENERGY MATERIALS, vol. 12, iss. 5, pp. 2103010, 2022.
DOI: 10.1002/aenm.202103010, IF = 29.368
Abstract: Environmentally sustainable, low-cost, flexible, and lightweight energy storage technologies require advancement in materials design in order to obtain more efficient organic metal-ion batteries. Synthetically tailored organic molecules, which react reversibly with lithium, may address the need for cost-effective and eco-friendly anodes used for organic/lithium battery technologies. Among them, carboxylic group-bearing molecules act as high-energy content anodes. Although organic molecules offer rich chemistry, allowing a high content of carboxyl groups to be installed on aromatic rings, they suffer from low conductivity and leakage to the electrolytes, which restricts their actual capacity, the charging/discharging rate, and eventually their application potential. Here, a densely carboxylated but conducting graphene derivative (graphene acid (GA)) is designed to circumvent these critical limitations, enabling effective operation without compromising the mechanical or chemical stability of the electrode. Experiments including operando Raman measurements and theoretical calculations reveal the excellent charge transport, redox activity, and lithium intercalation properties of the GA anode at the single-layer level, outperforming all reported organic anodes, including commercial monolayer graphene and graphene nanoplatelets. The practical capacity and rate capability of 800 mAh g−1 at 0.05 A g−1 and 174 mAh g−1 at 2.0 A g−1 demonstrate the true potential of GA anodes in advanced lithium-ion batteries.
C. R. Simmons, T. MacCulloch, M. Krepl, M. Matthies, A. Buchberger, I. Crawford, J. Šponer, P. Šulc, N. Stephanopoulos and H. Yan, "The influence of Holliday junction sequence and dynamics on DNA crystal self-assembly," NATURE COMMUNICATIONS, vol. 13, iss. 1, article no. 3112, 2022.
DOI: 10.1038/s41467-022-30779-6, IF = 14.919
Abstract: The programmable synthesis of rationally engineered crystal architectures for the precise arrangement of molecular species is a foundational goal in nanotechnology, and DNA has become one of the most prominent molecules for the construction of these materials. In particular, branched DNA junctions have been used as the central building block for the assembly of 3D lattices. Here, crystallography is used to probe the effect of all 36 immobile Holliday junction sequences on self-assembling DNA crystals. Contrary to the established paradigm in the field, most junctions yield crystals, with some enhancing the resolution or resulting in unique crystal symmetries. Unexpectedly, even the sequence adjacent to the junction has a significant effect on the crystal assemblies. Six of the immobile junction sequences are completely resistant to crystallization and thus deemed “fatal,” and molecular dynamics simulations reveal that these junctions invariably lack two discrete ion binding sites that are pivotal for crystal formation. The structures and dynamics detailed here could be used to inform future designs of both crystals and DNA nanostructures more broadly, and have potential implications for the molecular engineering of applied nanoelectronics, nanophotonics, and catalysis within the crystalline context.
D. D. Chronopoulos, H. Saini, I. Tantis, R. Zbořil, K. Jayaramulu and M. Otyepka, "Carbon Nanotube Based Metal–Organic Framework Hybrids From Fundamentals Toward Applications," SMALL, vol. 18, iss. 4, pp. 2104628, 2022.
DOI: 10.1002/smll.202104628, IF = 13.281
Abstract: Metal–organic frameworks (MOFs) materials constructed by the coordination chemistry of metal ions and organic ligands are important members of the crystalline materials family. Owing to their exceptional properties, for example, high porosity, tunable pore size, and large surface area, MOFs have been applied in several fields such as gas or liquid adsorbents, sensors, batteries, and supercapacitors. However, poor conductivity and low stability hamper their potential applications in several attractive fields such as energy and gas storage. The integration of MOFs with carbon nanotubes (CNTs), a well-established carbon allotrope that exhibits high conductivity and stability, has been proposed as an efficient strategy to overcome such limitations. By combining the advantages of MOFs and CNTs, a wide variety of composites can be prepared with properties superior to their parent materials. This review provides a comprehensive summary of the preparation of CNT@MOF composites and focuses on their recent applications in several important fields, such as water purification, gas storage and separation, sensing, electrocatalysis, and energy storage (supercapacitors and batteries). Future challenges and prospects for CNT@MOF composites are also discussed.
H. Saini, E. Otyepková, A. Schneemann, R. Zbořil, M. Otyepka, R. A. Fischer and K. Jayaramulu, "Hierarchical porous metal–organic framework materials for efficient oil–water separation," JOURNAL OF MATERIALS CHEMISTRY A, vol. 10, iss. 6, pp. 2751-2785, 2022.
DOI: 10.1039/d1ta10008d, IF = 12.732
Abstract: Oil contaminated water is a global issue, decreasing the quality of water sources and is posing a threat to the health of humans and many ecosystems. The utilization of industrial level strategies is limited mainly due to their complex and time-consuming processing. Considering this, we choose materials for separating oils from water based on their ease of handling and good performance. However, high surface area porous materials, such as linens, zeolites, cotton, etc., offer low efficiency for oil/water separation. Special wettability is the most promising property of materials and is helpful for oil–water separation. Metal–organic frameworks (MOFs), a class of highly tunable porous structures of metal clusters/ions and multidentate organic ligands, offer exciting prospects for various applications. The unique tunability of the structure and properties of these materials can endow them with special wettability for the treatment of oily water. This review focuses on hydrophobic–oleophilic, hydrophilic–underwater oleophobic and switchable wettability MOFs and their implementation as oil/water separating materials. We classify different MOF-based materials as filtration materials, absorbents or adsorbents based on the methodology they are used in for separating oil/water mixtures and emulsions. We discuss different subclasses of MOF-based filtration, absorbent and adsorbent materials and summarize recent developments in their oil/water separation applications. Finally, we end our discussion by critically analyzing the importance of these MOFs for separating oils from water and highlighting potential future directions for achieving improved performance.
J. M. Flauzino, E. P. Nguyen, Q. Yang, G. Rosati, D. Panáček, A. G. Brito-Madurro, J. M. Madurro, A. Bakandritsos, M. Otyepka and A. Merkoçi, "Label-free and reagentless electrochemical genosensor based on graphene acid for meat adulteration detection," BIOSENSORS AND BIOELECTRONICS, vol. 195, pp. 113628, 2022.
DOI: 10.1016/j.bios.2021.113628, IF = 10.618
Abstract: With the increased demand for beef in emerging markets, the development of quality-control diagnostics that are fast, cheap and easy to handle is essential. Especially where beef must be free from pork residues, due to religious, cultural or allergic reasons, the availability of such diagnostic tools is crucial. In this work, we report a label-free impedimetric genosensor for the sensitive detection of pork residues in meat, by leveraging the biosensing capabilities of graphene acid - a densely and selectively functionalized graphene derivative. A single stranded DNA probe, specific for the pork mitochondrial genome, was immobilized onto carbon screen-printed electrodes modified with graphene acid. It was demonstrated that graphene acid improved the charge transport properties of the electrode, following a simple and rapid electrode modification and detection protocol. Using non-faradaic electrochemical impedance spectroscopy, which does not require any electrochemical indicators or redox pairs, the detection of pork residues in beef was achieved in less than 45 min (including sample preparation), with a limit of detection of 9% w/w pork content in beef samples. Importantly, the sample did not need to be purified or amplified, and the biosensor retained its performance properties unchanged for at least 4 weeks. This set of features places the present pork DNA sensor among the most attractive for further development and commercialization. Furthermore, it paves the way for the development of sensitive and selective point-of-need sensing devices for label-free, fast, simple and reliable monitoring of meat purity.
I. Dědek, V. Kupka, P. Jakubec, V. Šedajová, K. Jayaramulu and M. Otyepka, "Metal-organic framework/conductive polymer hybrid materials for supercapacitors," APPLIED MATERIALS TODAY, vol. 26, pp. 101387, 2022.
DOI: 10.1016/j.apmt.2022.101387, IF = 10.041
Abstract: This review article focuses on supercapacitor electrode materials based on composites of metal-organic frameworks (MOFs) and conductive polymers (CPs). MOFs have attracted enormous attention due to their unique properties such as high porosity, nanoscale periodicity, large surface area and structural diversity. The major disadvantage of MOFs for energy storage applications is their low electrical conductivity. Combining MOFs with other (nano)materials is an effective strategy to increase the specific capacitance and overall performance of electrode materials. CPs are attractive compounds because of their controllable conductivity and mechanical properties, particularly including large specific capacitance, ease of fabrication, high environmental stability and good film-forming properties. This review mostly deals with hybridization strategies and discusses critically various types of CPs with different MOFs in relation to hybridization techniques and obtained results. An excellent summary of MOF@CP hybrids is provided with respect to recent advances in this field and presents new perspectives for enhancing the electrochemical performance of future MOF@CP supercapacitors.
L. Giri, S. R. Rout, R. S. Varma, M. Otyepka, K. Jayaramulu and R. Dandela, "Recent advancements in metal–organic frameworks integrating quantum dots (QDs@MOF) and their potential applications," NANOTECHNOLOGY REVIEWS, vol. 11, iss. 1, pp. 1947-1976, 2022.
DOI: 10.1515/ntrev-2022-0118, IF = 7.848
Abstract: Design and development of new materials and their hybrids are key to addressing current energy issues. Thanks to their tunable textural and physiochemical properties, metal–organic frameworks (MOFs) show great potential toward gas sorption, catalysis, sensing, and electrochemical energy applications. Nevertheless, practical applications of MOFs have been hampered because of their limited electrical conductivity, micropore size, and poor stability. However, smart integration of zero-dimensional quantum dots (QDs) into an MOF template, where the host structure offers suitable interactions for enhancing the stability and synergic properties, may be a solution. The objective of this review is to summarize recent advances in the field of QD@MOFs, highlighting fresh approaches to synthesis strategies and progress made in their application to optoelectronic devices, sensing, biomedical, catalysis, and energy storage. The current challenges and future directions of QDs@MOFs hybrids toward advancing energy and environmental applications are also addressed. We anticipate that this review will inspire researchers to develop novel MOF hybrids for energy, optoelectronics, and biomedical applications.
R. Langer, K. Mustonen, A. Markevich, M. Otyepka, T. Susi and P. Błoński, "Graphene Lattices with Embedded Transition-Metal Atoms and Tunable Magnetic Anisotropy Energy: Implications for Spintronic Devices," ACS APPLIED NANO MATERIALS, vol. 5, iss. 1, pp. 1562-1573, 2022.
DOI: 10.1021/acsanm.1c04309, IF = 5.097
Abstract: Doping of the graphene lattice with transition-metal atoms resulting in a high magnetic anisotropy energy (MAE) is an important goal of materials research owing to its potential application in spintronics. In this article, using spin-polarized density functional theory including spin–orbit coupling, we examined the magnetic properties of graphene with vacancy defects, both bare and nitrogen-decorated, and doped by Cr, Mn, and Fe transition-metal single atom (TM-SA) and two different TM atoms simultaneously. The adsorption of a second TM atom on an already embedded TM atom, i.e., the formation of upright TM dimers, was also considered. It is found that the graphene-mediated coupling between TM dopants can significantly increase MAE compared to that of SA impurities. While the MAE of TM-SA did not exceed 2 meV, it was enhanced to −23 meV for Cr and Fe simultaneously embedded into two separated double-vacancy (DV) defects and to a remarkably high value of 119.7 meV for two upright Fe–Mn dimers bound to two separate DVs, considerably exceeding the sum for individual TM-SAs. The latter MAE corresponds to a blocking temperature of 34 K assuming a relaxation time of 10 years. The origin of the enhanced MAE is discussed in relation to the spin excitations at the Fermi level and changes in d-derived states accompanying the rotation of the magnetization between in-plane and out-of-plane directions. We demonstrate that the presence of partially occupied degenerate states at the Fermi level favors its formation. The stability of the systems is also discussed. The computational findings are supplemented by an atomic-resolution characterization of an incidental Mn impurity bonded to four carbon atoms, whose localized spin matches expectations as measured using core-level electron energy-loss spectroscopy. Conducting TM-doped graphene with robust magnetic features offers prospects for the design of graphene-based spintronic devices.
S. M. H. Hejazi, M. Shahrezaei, P. Błoński, M. Allieta, P. M. Sheverdyaeva, P. Moras, Z. Baďura, S. Kalytchuk, E. Mohammadi, R. Zbořil, Š. Kment, M. Otyepka, A. Naldoni and P. Fornasiero, "Defect engineering over anisotropic brookite toward substrate-specific photo-oxidation of alcohols," CHEM CATALYSIS, vol. 2, iss. 5, pp. 1177-1190, 2022.
DOI: 10.1016/j.checat.2022.03.015, CiteScore = 4.0
Abstract: Generally adopted strategies for enhancing the photocatalytic activity are aimed at tuning the visible light response, the exposed crystal facets, and the nanocrystal shape. Here, we present a different approach for designing efficient photocatalysts displaying a substrate-specific reactivity upon defect engineering. The platinized, defective anisotropic brookite TiO2 photocatalysts are tested for alcohol photoreforming showing up to an 11-fold increase in methanol oxidation rate, compared with the pristine one, while presenting much lower ethanol or isopropanol specific oxidation rates. We demonstrate that the substrate-specific alcohol oxidation and hydrogen evolution reactions are tightly related, and when the former is increased, the latter is boosted. The reduced anisotropic brookite shows up to 18-fold higher specific photoactivity with respect to anatase and brookite with isotropic nanocrystals. Advanced in situ characterizations and theoretical investigations reveal that controlled engineering over oxygen vacancies and lattice strain produces large electron polarons hosting the substrate-specific active sites for alcohol photo-oxidation.