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To develop high-performance low-Pt electrocatalysts for direct alcohol fuel cells (DAFCs), we herein propose an interfacial engineering strategy, using interfacial Ag nanowire arrays as a sacrificing template and successfully fabricating a AgPtAu nanotrough array catalyst at water/air interfaces. By adjusting the conditions of interfacial reaction, composition-varied AgPtAu nanotrough arrays can be easily obtained. The formation of a trough-like morphology of AgPtAu can be attributed to the interface-confined Ag nanowire arrays reacting successively with PtCl62− and AuCl4− in the water phase. Optimized surface-Pt-rich Ag11Pt5Au84 nanotrough arrays exhibit ∼2270 and ∼2290 mA mgAu+Pt−1 in the mass activity towards methanol and ethanol electrooxidation, respectively, ∼3 times better than that of commercial Pt/C, and show improved tolerance towards CO-like carbonaceous intermediates. This work suggests that properly combining the positive catalytic effects of morphology and composition may be a possible avenue to tackle the issue of low-Pt electrocatalysts for DAFCs. [ABSTRACT FROM AUTHOR]

Seawater electrolysis provides a desirable pathway for large-scale production of green hydrogen without dependence on freshwater. However, its practical application is seriously hindered by low energy efficiency and insufficient durability because of the detrimental chlorine electro-oxidation and complex components of seawater. Herein, 2D MoN/Co2N hybrid nanosheets grown on 1D Cu nanowires and integrated on 3D Cu foam electrodes (Co/Mo–N–C/Cu) were fabricated for seawater splitting, which could enable the alkaline seawater electrolyzer assembled with these hierarchically structural electrodes to achieve a current density of 100 mA cm−2 at a low voltage of 1.70 V, along with good stability due to the synergistic effect among the MoN/Co2N hybrid nanosheets, unique 1D/2D/3D hierarchical structure, and the N-doped carbon protection layer. Theoretical calculations demonstrated that strong electron transfer occurred at heterogeneous interfaces, which could mediate the adsorption and desorption of intermediates, thus reducing the reaction energy barriers. [ABSTRACT FROM AUTHOR]

An electrochemical dehydrogenative [2 + 2 + 1] annulation used for the synthesis of imidazoles has been developed under undivided electrolytic conditions. In an undivided cell, aryl ketones and amines can smoothly participate in this transformation to furnish a variety of substituted imidazoles. The reaction avoids the use of both transition-metal catalysts and peroxide reagents, which makes it more sustainable and renewable. [ABSTRACT FROM AUTHOR]

The gene CCT67099 from Fusarium fujikuroi was shown to encode a novel enzyme from the Lytic Polysaccharide Monooxygenase (LPMO) Family AA11. The gene was expressed and a truncated version of the enzyme, designated as FfAA11, was purified from the periplasmic space of Escherichia coli cells at high yield. FfAA11 exhibited oxidative activity against α- and β-chitins, as well as lobster shells. Under optimised conditions, FfAA11 introduced 35 nmol of carboxylate (COO−) moieties per milligram of α-chitin. These carboxylate groups were introduced onto the chitin surface under mild enzymatic oxidation conditions in an aqueous solution without changes to the crystallinity of the chitin fibres. FfAA11 was also combined with a simple and environmentally friendly chemical method that transforms recalcitrant chitins into desirable functionalised (nano)materials. The use of ethyl(hydroxyimino)cyanoacetate (Oxyma)-assisted click chemistry allowed the rapid modification of the surface of FfAA11-oxidized chitins, with a fluorescent probe, a peptide, and gold nanoparticles. The chemical steps performed, including the FfAA11 oxidase treatment and surface chemical modification, were achieved without the production of any toxic by-products or waste organic solvents. This approach represents a novel method for the greener production of chitin-based biomaterials. [ABSTRACT FROM AUTHOR]

The efficient capture and chemical conversion of carbon dioxide (CO2) requires a solid simultaneously with a large surface area and highly effective active sites. Herein, imidazolinium based porous hypercrosslinked ionic polymers (HIPs) with a high surface area, rich micro/mesoporosity and abundant ionic sites were constructed via the hypercrosslinkage of 2-phenylimidazoline and benzyl halides, in which quaternization and Friedel–Crafts alkylation happened simultaneously to afford ionic polymeric networks. The obtained HIPs were efficient in the selective capture of CO2 and cycloaddition of CO2 with epoxides. High yield, stable reusability and good substrate compatibility were achieved under mild conditions (down to ambient conditions), dramatically outperforming the homogeneous ionic liquid monomer and post-modified analogues. The synergistic adsorption and conversion enabled the efficient low-temperature conversion of diluted CO2 (0.15 bar CO2 and 0.85 bar nitrogen, the simulation of flue gas) catalyzed by HIPs in the presence of co-catalyst ZnBr2. The in situ formed ionic sites with a high leaving ability being homogeneously embedded in the hypercrosslinked polymeric skeleton responded to the high adsorption and catalysis performance. This work highlights the functional HIPs as a versatile platform to reach efficient CO2 capture and conversion under mild conditions. [ABSTRACT FROM AUTHOR]

Nucleophile oxidation reactions, represented by the incomplete methanol oxidation reaction (i-MOR) to formic acid, can effectively lower the potential of electrolytic hydrogen production while generating high-value products. In order to achieve an industrial grade i-MOR coupled with hydrogen production, designing efficient catalysts toward the i-MOR becomes crucial. In this work, a nickel–cobalt-layered double hydroxide (NiCo-LDH) catalyst incorporating an Fe-based "electron pump" is developed in accordance with the classic two-step NOR mechanism of Ni-based active sites. The coordinating effect of Co effectively reduces the oxidation potential of Ni(II / III) in NiCo-LDH, thus reducing the potential differential between it and the oxidation potential of Fe(II / III), consequently establishing an efficient electron transport pathway from Ni to Fe. Owing to the spontaneous dehydrogenation of methanol, elemental Fe can achieve a valence change during the i-MOR catalytic process. The "electron pump" composed of valence-change Fe effectively enhances the electron transfer, thus ensuring the efficient utilization of electron-deficient active Ni sites throughout the catalytic process. Therefore, FeEP-NiCo-LDH demonstrates outstanding i-MOR catalytic activity, with a potential requirement of 1.349 V (vs. RHE) and 1.430 V to deliver current densities of 10 mA cm−2 and 100 mA cm−2, respectively, while maintaining a Faraday efficiency of ca. 95%. [ABSTRACT FROM AUTHOR]

N,N-Dimethylformamide (DMF) is a universal solvent with wide applications across various industries. Current industrial synthesis requires high temperature and high pressure, starting from fossil-based carbon monoxide and dimethylamine (DMA). Herein, we report a green and electrochemical strategy to produce DMF under ambient conditions through direct oxidation of trimethylamine (TMA), which is a surplus chemical in DMA manufacturing. DMF production with 80% yield and >50% faradaic efficiency was achieved in an H-cell reactor over a graphite anode, coupled with hydrogen production at the cathode. Mechanistic investigations show that the reaction occurs through two-phase oxidation and that an aminal serves as the key intermediate. To achieve continuous DMF production, we set up a membrane-electrode assembly (MEA) flow reactor (2 cm × 2 cm), achieving a DMF productivity of 25 μmol h−1 and a faradaic efficiency of 40%. To further increase the productivity, we fabricated another membrane-free flow reactor (8 cm × 9 cm), delivering a high formation rate (550 μmol h−1) with high selectivity (>90%) at a constant current of 3 A in a 100-hour test. This study offers a unique opportunity to utilize electricity to drive surplus chemical utilization under ambient conditions, contributing to the sustainability of the chemical industry in the future. [ABSTRACT FROM AUTHOR]

Herein, we have developed metal and oxidant-free visible light-promoted alkene vs. alkyne regio- and chemoselective radical cascade cyclization of electronically unbiased 1,6-enynes with chalcogens to synthesize substituted pyrrolidines bearing chalcogens. The reaction generated three new bonds, namely, C–SO2, C–C, and C–Se under extremely mild conditions. Furthermore, we achieved regio- and chemoselective mono-addition of aromatic thiophenols with unactivated 1,6-enynes. The key features of this protocol are broad substrate scope, environment-friendly conditions, operational simplicity, atom economy, and amenability to gram-scale synthesis. The mechanistic studies corroborate that the reaction proceeds via a radical pathway. [ABSTRACT FROM AUTHOR]

Optically pure 1,2,3,4-tetrahydroisoquinoline carboxylic acids are important chiral building blocks in the pharmaceutical and fine chemical industries. However, the existing chemo-enzymatic deracemization method employing D -amino acid oxidase from Fusarium solani M-0718 (FsDAAO) suffers from the requirement for a large excess of a nonselective chemical reducing agent. To explore an alternative method, we envisaged a concurrent biocatalytic oxidation and reduction cascade in one pot. Herein, we report a novel biocatalytic route for the asymmetric reduction of 3,4-dihydroisoquinoline-1-carboxylic acids employing Δ1-piperidine-2-carboxylate/Δ1-pyrrolidine-2-carboxylate reductase from Pseudomonas putida KT2440 (PpDpkA) as a biocatalyst, yielding the corresponding (S)-1-carboxyl-substituted tetrahydroisoquinolines with high conversions and enantiomeric excess (>99% ee). By combining FsDAAO and PpDpkA in one pot, a fully biocatalytic method was demonstrated for the deracemization of a range of racemic 1-carboxyl substituted tetrahydroisoquinolines to produce the corresponding (S)-enantiomers with >99% conversions and >99% ee. Furthermore, preparative-scale biotransformation of racemic 1,2,3,4-tetrahydroisoquinoline-1-carboxylic acid gave the (S)-enantiomer with 89% isolated yield and >99% ee. Taken together, we provide an enantioselective biocatalytic redox cascade method for the one-pot synthesis of enantiopure 1,2,3,4-tetrahydroisoquinoline carboxylic acids. [ABSTRACT FROM AUTHOR]

An ultramild reaction condition for the hydrocarbonylation of alkynes, which is performed under atmospheric pressure of CO in the absence of acids, has been developed. Palladium hydride (Pd-H) generated from triethylsilane (Et3SiH) rather than the traditionally used strong acid (HX) is applied for the first time in this transformation. In addition, an unusual counteranion-controlled linear and branch selectivity for terminal alkynes is observed under otherwise identical conditions. A wide range of 1,1-, 1,2-, and 1,2,2-substituted α,β-unsaturated thioesters or amides are regioselectively obtained from terminal and internal alkynes in moderate to excellent yields. Furthermore, the first enantioselective construction of indolone derivatives with a C–N chiral axis is achieved when using 2-(tert-butyl)-N-(2-alkynylphenyl)aniline as the substrate in the presence of TMS-SYNPHOS as the chiral ligand. [ABSTRACT FROM AUTHOR]

Transfer hydrogenation of nitroarenes to the corresponding anilines using hydrazine hydrate and non-noble metal catalysts has already been widely studied. However, the toxicity resulting from excess hydrazine hydrate and the high reaction temperature limit its industrial application. Herein, a novel N-doped molybdenum oxide compound (Mo4O4N3) was in situ prepared from g-C3N4 and (NH4)6Mo7O24·4H2O (AHM). The as-prepared Mo4O4N3 can achieve a 99% yield of aniline using a stoichiometric molar ratio of hydrazine hydrate (–NO2 : N2H4·H2O = 1 : 1.5) at room temperature for 50 minutes. Mechanistic experiments and characterization techniques indicate that the acidic sites of unsaturated Mo in Mo4O4N3 can efficiently activate N2H4 molecules to form active hydrogen species for catalytic transfer hydrogenation of nitroarenes without the generation of hazardous NH3. Besides, Mo4O4N3 still exhibited excellent catalytic performance for the large-scale reaction without solvent. This work may offer a feasible and efficient strategy for arylamine production. [ABSTRACT FROM AUTHOR]

Lignin is an abundant source of aromatics, and the depolymerization of lignin provides significant potential for producing high-value chemicals. Selective hydrogenolysis of the C–O ether bond in lignin is an important strategy for the production of fuels and chemical feedstocks. In our study, catalytic hydrogenolysis of lignin model compounds (β-O-4, α-O-4 and 4-O-5 model compounds) over Ni3S2-CS catalysts was investigated. Hence, an array of 2D carbon nanostructure Ni3S2-CSs-X-Y derived catalysts were produced using different compositions at different temperatures (X = 0 mg, 0.2 mg, 0.4 mg, 0.6 mg, and 0.8 mg; Y = 600 °C, 700 °C, 800 °C, and 900 °C) were prepared and applied for hydrogenolysis of lignin model compounds and depolymerization of alkaline lignin. The highest conversion of lignin model compounds (β-O-4 model compound) was up to 100% and the yield of the obtained corresponding ethylbenzene and phenol could achieve 92% and 86%, respectively, over the optimal Ni3S2-CSs-0.4-700 catalyst in iPrOH at 260 °C without external H2. The 2D carbon nanostructure catalysts performed a good dispersion on the surface of the carbon nanosheets, which facilitated the cleavage of the lignin ether bonds. The physicochemical characterization studies were carried out by means of XRD, SEM, TEM, H2-TPR, NH3-TPD, Raman and XPS analyses. Based on the optimal reaction conditions (260 °C, 4 h, 2.0 MPa N2), various model compounds (β-O-4, α-O-4 and 4-O-5 model compounds) could also be effectively hydrotreated to produce the corresponding aromatic products. Furthermore, the optimal Ni3S2-CSs-0.4-700 catalyst could be carried out in the next five consecutive cycle experiments with a slight decrease in the transformation of lignin model compounds. [ABSTRACT FROM AUTHOR]

The visible-light-promoted cascade cyclization of 2-haloaryl isothiocyanates and isocyanides to access benzo[d]imidazo[5,1-b]thiazoles has been realized efficiently under metal- and photocatalyst-free conditions. The reaction mechanism was explored by several preliminary experiments involving reactive intermediate, free radical inhibitors, and corresponding photoelectric spectra. This protocol possesses some advantages over the previous methods such as readily available and inexpensive substrates, metal catalyst-free, step and atom economy, and mild reaction conditions. [ABSTRACT FROM AUTHOR]

Harvesting solar energy to drive highly efficient photocatalytic conversion of renewable biomass and its derivatives to value-added chemicals with the concomitant formation of hydrogen (H2) is a green and promising strategy to cope with the global energy dilemma. In this context, we have reported the facile assembly of uniformly distributed CdS nanoparticles (NPs) on the two-dimensional (2D) platform of Ti3C2Tx MXene nanosheets (NSs) via a low-temperature wet chemistry process, during which tight interfacial contact between CdS and Ti3C2Tx has been realized. The Ti3C2Tx/CdS composites feature remarkable enhancement in the aqueous-phase photoredox conversion of furfural alcohol to furfural and H2 by simultaneously utilizing photoexcited holes and electrons. Mechanistic studies reveal that the Ti3C2Tx MXene acts as an "electron sink" to capture the electrons generated from CdS and the close interfacial connection expedites the separation and transport of photoexcited charge carriers, thereby accelerating the photocatalytic performance of the Ti3C2Tx/CdS composites. We anticipate that this work would provide an instructive paradigm for further rational design of MXene/semiconductor hybrids for photoredox-catalyzed production of value-added products and H2 from biomass intermediates. [ABSTRACT FROM AUTHOR]

Design of stable high-performance heterogeneous catalysts has become crucial for efficient catalytic conversion of renewable biomass into high value-added chemicals. Noble metal alloy nanoparticles (NPs) are of great interest due to their unique tunable structures and high activity. In this study, Au–Pd alloy NPs supported on hydrophilic mesoporous poly(ionic liquid) (MPIL) exhibited encouragingly high performance in the aerobic oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) in water under mild conditions. Nearly complete conversion of HMF is attained at a low temperature of 90 °C under atmospheric O2, resulting in 99% FDCA yield and high turnover number (TON) of up to 350. After reaction, the catalyst can be facilely recovered and reused with stable activity. Surface wettability plays a dominant role in the oxidation of HMF to FDCA, and synergistic alloy effect accounts for high activity. The results also show that MPILs are a promising support platform to achieve stable and efficient metal NPs through task-specific design of functional monomers. [ABSTRACT FROM AUTHOR]

The regio- and stereoselective ring-opening of spiro-epoxyoxindoles with ammonia has been reported for the construction of 3-hydroxy-3-aminomethyloxindoles in high yields (up to 90%) and enantioselectivities (up to 99% ee) under mild and catalyst-free conditions. The reaction could be scaled up to the gram-scale and be used in the synthesis of analogues of dioxibrassinin and spirobrassinin. [ABSTRACT FROM AUTHOR]