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An extensive thermodynamic study of N-methylformamide (CAS RN: 123-39-7) and N,N-dimethylformamide (CAS RN: 68-12-2), is presented in this work. The liquid heat capacities of N-methylformamide were measured by Tian–Calvet calorimetry in the temperature interval (250–300) K. The vapor pressures for N-methylformamide and N,N-dimethylformamide were measured using static method in the temperature range 238 K to 308 K. The ideal-gas thermodynamic properties were calculated using a combination of the density functional theory (DFT) and statistical thermodynamics. A consistent thermodynamic description was developed using the method of simultaneous correlation, where the experimental and selected literature data for vapor pressures, vaporization enthalpies, and liquid phase heat capacities and the calculated ideal-gas heat capacities were treated together to ensure overall thermodynamic consistency of the results. The resulting vapor pressure equation is valid from the triple point to the normal boiling point temperature. [ABSTRACT FROM AUTHOR]

The large‐scale application of water electrolysis, for clean H2 production, requires the development of eco‐friendly and low‐cost electrocatalysts with high activity for hydrogen evolution reaction (HER) in alkaline media. The excellent alternatives to the benchmark noble metal‐based HER electrocatalyst are transition metal oxides (TMO). Because of the nontoxicity, cost‐effectiveness, availability, and easy electronic structure tuning, zinc oxide (ZnO) is a good TMO candidate. However, ZnO shows poor performance for HER electrocatalysis and therefore has been much less reported. Herein, it is reported that ZnO can be developed as a good HER electrocatalyst in alkaline media through simultaneously proper cobalt loading at the precursor level (coordination polymer) and defects engineering. The optimum amount of cobalt in ZnO shows an overpotential of 385 mV at 10 mA cm−2 (lower than that of ZnO and Co3O4) and a small Tafel slope of 76 mV dec−1. The introduction of cobalt at the precursor level and subsequently in the wurtzite frame of ZnO as revealed by the analyses, allows to considerably lower the bandgap and increasing the number of defects in the structure, thereby boosting the electrocatalytic performance. This work highlights the potential of cheap and environmentally friendly TMO as alternative HER electrocatalysts for large‐scale alkaline water electrolysis. [ABSTRACT FROM AUTHOR]

The growing demand for substitutes of lithium chemistries in battery leads to a surge in budding novel anion‐based electrochemical energy storage, where the chloride ion batteries (CIBs) take over the role. The application of CIBs is limited by the dissolution and side reaction of chloride‐based electrode materials in a liquid electrolyte. On the flipside, its solid‐state electrolytes are scarcely reported due to the challenge in realizing fast Cl− conductivity. The present study reports [Al(DMSO)6]Cl3, a solid‐state metal–organic material, allows chloride ion transfer. The strong Al‐Cl bonds in AlCl3 are broken down after coordinating of Al3+ by ligand DMSO, and Cl− in the resulting compound is weakly bound to complexions [Al(DMSO)6]3+, which may facilitate Cl− migration. By partial replacement of Cl− with PF6−, the room‐temperature ionic conductivity of as‐prepared electrolyte is increased by one order of magnitude from 2.172 × 10−5 S cm−1 to 2.012 × 10−4 S cm−1. When they are assembled with Ag (anode)/Ag–AgCl (cathode) electrode system, reversible electrochemical redox reactions occur on both sides, demonstrating its potential for solid‐state chloride ion batteries. The strategy by weakening the bonding interaction using organic ligands between Cl− and central metallic ions may provide new ideas for developing solid chloride‐ion conductors. [ABSTRACT FROM AUTHOR]

2D materials are being widely investigated for their potential application in light‐detecting devices. Very recently, a spin‐coated flexible 2D germanium‐based photodetector with great photocurrent density and responsivity as well as short rise and decay time is presented by Liu et. al. In this paper, the solid‐state single flake photodetector base on either pure germanane or (3‐hydroxypropyl)germanane is reported. Both prepared photodetectors while irradiated with different wavelengths of light exhibit outstanding responsivity of 1157 mA W−1 for GeH and 362 mA W−1 for (3‐hydroxypropyl)germanane, which exceeds Liu's flexible reported GeH photodetector (22 µA W−1) by more than five orders of magnitude. These constructed photodetectors also exhibit rise and fall times lower than 20 ms, which is also significantly faster than the GeH photodetector reported by Liu with rise and decay times 240 and 740 ms, respectively. [ABSTRACT FROM AUTHOR]

Two‐dimensional nanomaterials, as one of the most widely used substrates for energy storage devices, have achieved great success in terms of the overall capacity. Despite the extensive research effort dedicated to this field, there are still major challenges concerning capacitance modulation and stability of the 2D materials that need to be overcome. Doping of the crystal structures, pillaring methods and 3D structuring of electrodes have been proposed to improve the material properties. However, these strategies are usually accompanied by a significant increase in the cost of the entire material preparation process and also a lack of the versatility for modification of the various types of the chemical structures. Hence in this work, versatile, cheap, and environmentally friendly method for the enhancement of the electrochemical parameter of various MXene‐based supercapacitors (Ti3C2, Nb2C, and V2C), coated with functional and charged organic molecules (zwitterions—ZW) is introduced. The MXene‐organic hybrid strategy significantly increases the ionic absorption (capacitance boost) and also forms a passivation layer on the oxidation‐prone surface of the MXene through the covalent bonds. Therefore, this work demonstrates a new, cost‐effective, and versatile approach (MXene‐organic hybrid strategy) for the design and fabrication of hybrid MXene‐base electrode materials for energy storage/conversion systems. [ABSTRACT FROM AUTHOR]

Catalyst recovery is an integral part of photoredox catalysis. It is often solved by adding another component-a sacrificial agent-whose role is to convert the catalyst back into its original oxidation state. However, an additive may cause a side reaction thus decreasing the selectivity and overall efficiency. Herein, we present a novel approach towards chemoselective photooxidation reactions based on suitable solvent-acetonitrile acting simultaneously as an electron acceptor for catalyst recovery, and on anaerobic conditions. This is allowed by the unique properties of the catalyst, 7,8-dimethoxy-3-methyl-5-phenyl-5-deazaflavinium chloride existing in both strongly oxidizing and reducing forms, whose strength is increased by excitation with visible light. Usefulness of this system is demonstrated in chemoselective dehydrogenations of 4-methoxy- and 4-chlorobenzyl alcohols to aldehydes without over-oxidation to benzoic acids achieving yields up to 70 %. 4-Substituted 1-phenylethanols were oxidized to ketones with yields 80-100 % and, moreover, with yields 31-98 % in the presence of benzylic methyl group, diphenylmethane or thioanisole which are readily oxidized in the presence of oxygen but these were untouched with our system. Mechanistic studies based on UV-Vis spectro-electrochemistry, EPR and time-resolved spectroscopy measurements showed that the process involving an electron release from an excited deazaflavin radical to acetonitrile under formation of solvated electron is crucial for the catalyst recovery., (© 2022 Wiley-VCH GmbH.)

Even though WS 2 nanotubes (NTs-WS 2 ) have great potential as anode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) thanks to their unusual layered structure, their conductivity and cycling stability are far from satisfactory. To tackle these issues, carbon-coated WS 2 (NTs-WS 2 @C) nanocomposites were prepared through a facile synthesis method that involved precipitating a carbon precursor (20% sucrose) on WS 2 nanotubes, followed by annealing treatment under an argon environment. Thanks to the presence of highly conductive and mechanically robust carbon on the outer surface, NTs-WS 2 @C nanocomposites show improved electrochemical performance compared with bare NTs-WS 2 . After 60 cycles at 80 mA g -1 current density, the cells display high capacities of 305 mAh g -1 in LIBs and 152 mAh g -1 in SIBs, respectively. As the current density increases to 600 mA g -1 , it provides specific capacities of 209 and 115 mAh g -1 , correspondingly. The enhanced electrochemical performance in LIBs and SIBs is primarily attributed to the synergistic effects of the tubular architecture of WS 2 , carbon network and stable nanocomposite structure, which can effectively constrain volume variation during the metal ions intercalation/deintercalation processes.

Fluorographene is the youngest stoichiometric derivative of graphene; hence, its reactivity is only poorly explored. Compared to graphene, the significantly higher reactivity of C-F bonds makes this material a suitable platform for a large number of chemical modifications. Fluorographene is also the only member of the halographene family that can be prepared in the stoichiometric composition (C 1 F 1 ). Herein, the chemical modification of fluorographene with Grignard reagents, which are well known in organic synthesis for the formation of new C-C bonds, is presented. The reaction with alkyl magnesium bromides led to successful modification of fluorographene with ethyl, vinyl, ethynyl and propargyl groups. Chemical characterisation showed the presence of covalently bonded functional groups in a high concentration exceeding one functional group per C 6 motif. The reactivity of Grignard reagents with fluorographene decreased from ethyl to ethynyl. The terminal carbon-carbon triple bonds were used for click reactions with organic azides leading to the formation of triazole rings. These findings open up a broad spectrum of opportunities for simple and robust modification of graphene by chemical reactions proceeding at room temperature under mild conditions. These results have major application potential in sensing, biomedical and energy-related applications., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In the last decade, graphene and graphene derivatives have become some of the most intensively studied materials. Tuning of the electronic and electrochemical properties of graphene is of paramount importance. In this study, six diazonium-modified graphenes containing different functional groups according to the diazonium salt precursor were investigated. These diazonium moieties have a strong mesomeric (resonance) effect and act as either electron-donating or -withdrawing species. Different graphene precursors, such as thermally and chemically reduced graphenes were studied. All the products were characterized in detail by elemental combustion analysis, FTIR spectroscopy, Raman spectroscopy, high-resolution X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry. Resistivity and zeta potential measurements were consistent with theoretical (DFT) calculations. The results show that chemical modification of graphene by diazotation strongly influences its properties, creating a huge application potential in microelectronics, energy storage and conversion devices, and electrocatalysis., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)