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Electrochemical dehydrogenation of hydroxides plays a crucial role in the formation of high‐valence metal active sites toward 5‐hydroxymethylfurfural oxidation reaction (HMFOR) to produce the value‐added chemical of 2,5‐furandicarboxylic (FDCA). Herein, we construct benzoic acid ligand‐hybridized NiCo(OH)x nanowires (BZ‐NiCo(OH)x) with ample electron‐deficient Ni/Co sites for HMFOR. The robust electron‐withdrawing capability of benzoic acid ligands in BZ‐NiCo(OH)x speeds up the electrochemical activation and dehydrogenation of lattice‐hydroxyl‐groups (M2+−O−H⇌M3+−O), boosting the formation of abundant electron‐deficient and high‐valence Ni/Co sites. DFT calculation reveals that the deintercalation proton is prone to establishing a hydrogen bridge with the carbonyl group in benzoic acid, facilitating the proton transfer. Coupled with the synergistic oxidation of Ni/Co sites on hydroxyl and aldehyde groups, BZ‐NiCo(OH)x delivers a remarkable current density of 111.20 mA cm−2 at 1.4 V for HMFOR, exceeding that of NiCo(OH)x by approximately fourfold. And the FDCA yield and Faraday efficiency are as high as 95.24 % and 95.39 %, respectively. The ligand‐hybridized strategy in this work introduces a novel perspective for designing high‐performance transition metal‐based electrocatalysts for biomass conversion. [ABSTRACT FROM AUTHOR]

Fabricating efficient oxygen evolution reaction (OER) electrocatalysts is crucial for water electrocatalysis. Herein, the spinel-type high-entropy oxides of (Co, Fe, Mn, Ni, Cr)3O4 were synthesized through the high-temperature calcination approach. The influences of calcination temperatures on structures and electrochemical properties were investigated. The optimized catalyst of HEO-900 contains the hybrid structure of regular polyhedrons and irregular nanoparticles, which is beneficial for the exposure of electrochemically active sites. It was identified that the abundant high-valence metal species of Ni3+, Co3+, Fe3+, Mn4+, and Cr3+ are formed during the OER process, which is generally regarded as the electrochemically active sites for OER. Because of the synergistic effect of multi-metal active sites, the optimized HEO-900 catalyst indicates excellent OER activity, which needs the overpotential of 366 mV to reach the current density of 10 mA cm−2. Moreover, HEO-900 reveals the prominent durability of running for 24 h at the current density of 10 mA cm−2 without clear delay. Therefore, this work supplies a promising route for preparing high-performance multi-metal OER electrocatalysts for water electrocatalysis application. [ABSTRACT FROM AUTHOR]

Exploring effective electrocatalysts for the oxygen reduction reaction (ORR) is of great significance for rechargeable Zn–air batteries (ZABs). In particular, heteroatom-doping in metal-nitrogen-carbon single-atom catalysts (SACs) is considered an effective strategy to promote the electrocatalytic ORR. Herein, we report a practical strategy for designing single-Fe atom decorated S/N-doped carbon (Fe SAs@S/N–C) through the polymerization of phenylenediamine materials as an efficient ORR catalyst for ZABs. The introduction of S facilitates the high-density doping of Fe–N4 active sites, and regulates the adsorption energy of oxygen-containing intermediates by altering the electronic structure of Fe–N4 active sites. Benefiting from the S-doped carbon structure, the Fe SAs@S/N–C catalyst exhibits outstanding ORR performance (E1/2 = 0.84 V) under alkaline conditions, possesses superior durability after 10 K cyclic voltammetry cycles and methanol resistance, outperforming the commercial 20 wt% Pt/C catalyst. Moreover, the Fe SAs@S/N–C catalyst can be easily synthesized at the gram scale, meeting the requirement of practical applications. The liquid-state ZABs assembled with the Fe SAs@S/N–C catalyst as the air cathode demonstrate a large peak power density of 156 mW cm−2 and long-cycling over 300 h. Moreover, the as-assembled flexible all-solid-state ZABs exhibit excellent cycle stability under various bending conditions, demonstrating the promising potential of substituting Pt-based catalysts in practical applications. [ABSTRACT FROM AUTHOR]

Precise manipulation of the coordination environment of single‐atom catalysts (SACs), particularly the simultaneous engineering of multiple coordination shells, is crucial to maximize their catalytic performance but remains challenging. Herein, we present a general two‐step strategy to fabricate a series of hollow carbon‐based SACs featuring asymmetric Zn−N2O2 moieties simultaneously modulated with S atoms in higher coordination shells of Zn centers (n≥2; designated as Zn−N2O2−S). Systematic analyses demonstrate that the synergetic effects between the N2O2 species in the first coordination shell and the S atoms in higher coordination shells lead to robust discrete Zn sites with the optimal electronic structure for selective O2 reduction to H2O2. Remarkably, the Zn−N2O2 moiety with S atoms in the second coordination shell possesses a nearly ideal Gibbs free energy for the key OOH* intermediate, which favors the formation and desorption of OOH* on Zn sites for H2O2 generation. Consequently, the Zn−N2O2−S SAC exhibits impressive electrochemical H2O2 production performance with high selectivity of 96 %. Even at a high current density of 80 mA cm−2 in the flow cell, it shows a high H2O2 production rate of 6.924 mol gcat−1 h−1 with an average Faradaic efficiency of 93.1 %, and excellent durability over 65 h. [ABSTRACT FROM AUTHOR]