Two-dimensional (2D) metal-organic framework (MOF) nanosheets have been recently regarded as the model electrocatalysts due to their porous structure, fast mass and ion transfer through the thickness, and large portion of exposed active metal centers. Combining them with electrically conductive 2D nanosheets is anticipated to achieve further improved performance in electrocatalysis. In this work, we in situ hybridized 2D cobalt 1,4-benzenedicarboxylate (CoBDC) with TiCT (the MXene phase) nanosheets via an interdiffusion reaction-assisted process. The resulting hybrid material was applied in the oxygen evolution reaction and achieved a current density of 10 mA cm at a potential of 1.64 V vs reversible hydrogen electrode and a Tafel slope of 48.2 mV dec in 0.1 M KOH. These results outperform those obtained by the standard IrO-based catalyst and are comparable with or even better than those achieved by the previously reported state-of-the-art transition-metal-based catalysts. While the CoBDC layer provided the highly porous structure and large active surface area, the electrically conductive and hydrophilic TiCT nanosheets enabled the rapid charge and ion transfer across the well-defined TiCT-CoBDC interface and facilitated the access of aqueous electrolyte to the catalytically active CoBDC surfaces. The hybrid nanosheets were further fabricated into an air cathode for a rechargeable zinc-air battery, which was successfully used to power a light-emitting diode. We believe that the in situ hybridization of MXenes and 2D MOFs with interface control will provide more opportunities for their use in energy-based applications.

A new and easily regenerable NAD(P)H model 9,10-dihydrophenanthridine (DHPD) has been designed for biomimetic asymmetric hydrogenation of imines and aromatic compounds. This reaction features the use of hydrogen gas as terminal reductant for the regeneration of the DHPD under the mild condition. Therefore, the substrate scope is not limited in benzoxazinones; the biomimetic asymmetric hydrogenation of benzoxazines, quinoxalines, and quinolines also gives excellent activities and enantioselectivities. Meanwhile, an unexpected reversal of enantioselectivity was observed between the reactions promoted by the different NAD(P)H models, which is ascribed to the different hydride transfer pathway. ■ INTRODUCTIONAs a couple of the most important coenzymes found in living cells, reduced nicotinamide adenine dinucleotide (NADH) and nicotinamide adenine dinucleotide phosphate (NADPH) play great roles in reduction−oxidation (redox) metabolism. 1 Therefore, NAD(P)H mimics have become one of the most significant fields in biomimetic chemistry over the past few decades (Figure 1). Despite that much progress has been achieved, most of the current research focuses on the hydride transfer ability and selectivity in redox reactions rather than the renewable capability of NAD(P)H models. 2As one of the simplest NAD(P)H models, Hantzsch esters (HEH) 3 have been widely and successfully used as reductant in the enantioselective transfer hydrogenation of unsaturated bonds (CC, CN, and CO) using organocatalysts 4,5 and metal catalysts (Figure 1). 6 Recently, we reported an efficient method for in situ regeneration of HEH from Hantzsch pyridine under hydrogen gas in biomimetic asymmetric hydrogenation (Scheme 1). 7a Although excellent enantioselectivities were obtained, the regeneration condition of HEH was harsh, and the substrate scope was limited to benzoxazinones which underwent no background reaction. Developing a milder biomimetic asymmetric hydrogenation is of great interest in the field of NAD(P)H mimics and good for extending the substrate generality. Based on our previous work on asymmetric hydrogenation, 8 we envisioned that looking for a new and easily regenerable NAD(P)H model is probably a good choice.To the best of our knowledge, the dihydropyridine amido group is the key structure in NAD(P)H models and plays an important part in the hydride transfer process. Therefore, most of the currently successful NAD(P)H models, such as HEH 3 and 1-benzyl-1,4-dihydronicotinamide (BNAH), 9 contain a dihydropyridine skeleton. Based on the design of NAD(P)H models, the search of NAD(P)H models that can be used in the

An environment-friendly and economical route for 5-hydroxymethylfurfural (HMF) aerobic oxidation to 2,5-furandicarboxylic acid (FDCA) in an ionic liquid (IL)-promoted base-free reaction system was reported using Fe–Zr–O as a catalyst.

2,5-Furandicarboxylic acid (FDCA), which is usually produced from HMF catalyzed by noble metal catalysts, is an important biobased monomer for the degradable polymer polyethylene furandicarboxylate (PEF). In order to reduce the high costs of starting material and catalysts, a novel approach for the direct conversion of fructose into FDCA was developed by employing [Bmim]Cl as a solvent with non-noble metal (Fe−Zr−O) as a catalyst. Relatively high FDCA yield was obtained at full fructose conversion under optimal conditions. The kinetic study revealed that the oxidation of intermediate FFCA to FDCA possessed the highest activation energy, indicating this step is most affected by reaction temperature. Additionally, in the IL-promoted reaction system, other biomass sources, such as glucose, galactose, mannose, starch, and cellulose also can be directly converted, with lower FDCA yield compared with that of fructose due to the ineffective isomerization of aldohexoses into fructose.

Ru nanodendrites composed of ultrathin fcc/hcp nanoblades were synthesized by a facile solvothermal reduction of Ru3+ together with Cu2+ followed by selective etching of Cu, resulting in a micro/mesoporous electrocatalyst that is highly efficient and stable for the hydrogen evolution reaction in alkaline media and outperformed commercial Pt/C at a lower cost.

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