Shaohui Zhang

This study deciphers the anionic modulation mechanism of halide ions (F⁻/Cl⁻) in cobalt-based hydroxides for oxygen evolution reaction (OER). Phase-pure Co(OH)₂, Co(OH)F, and Co₂(OH)₃Cl were fabricated via substrate-independent hydrothermal synthesis to eliminate conductive support interference. Electrocatalytic evaluation on glassy carbon electrodes demonstrates fluoride’s superior regulatory capability over chloride. X-ray photoelectron spectroscopy (XPS) analyses revealed that F⁻ incorporation induces charge redistribution through Co → F electron transfer, optimizing the electronic configuration via ligand effects. F⁻ incorporation simultaneously guided the anisotropic growth of 1D nanorods and reduced surface energy, thereby enhancing the wettability of Co(OH)F. The engineered Co(OH)F catalyst delivers exceptional OER performance: 318 mV overpotential at 10 mA/cm² in 1 M KOH with 94% current retention over 20 h operation. This study provides a synthetic strategy for preparing pure-phase Co(OH)F and compares halide ions’ effects on enhancing OER activity through electronic structure modulation and morphological control of basic cobalt salts.

The oxygen evolution reaction (OER), which involves a four-electron transfer and slow kinetics, requires an efficient catalyst to overcome the high energy barrier for high-performance water electrolysis. In this paper, a novel Ni₃S₂@V-NiFe(III) LDH/NF catalyst was prepared via a facile two-step hydrothermal method. The constructed heterostructure of Ni₃S₂@V-NiFe(III) LDH increases the specific surface area and regulates the electronic structure. Furthermore, the introduction of the V element forms an electron transport chain of Ni-O-Fe-O-V-O-Ni, which optimizes the binding energy between metal active sites and oxygen evolution reaction intermediates, accelerates electron transfer, and improves self-reconstruction. With this dual regulation strategy, Ni₃S₂@V-NiFe(III) LDH/NF exhibits exceptional OER performance with an overpotential of 280 mV at 100 mA/cm² and a Tafel slope of 45.4 mV/dec. This work develops a dual regulation strategy combining heterostructure formation and the doping effect, which are beneficial in the design of efficient OER catalysts.

Three-dimensional porous carbon materials with moderate heteroatom-doping have been extensively investigated as promising electrode materials for energy storage. In this study, we fabricated a 3D cross-linked chitosan-dicyandiamide-VOSO₄ hydrogel using a polymerization process. After pyrolysis at high temperature, 3D porous VO_x/N-doped carbon nanosheet hybrids (3D VNCN) were obtained. The unique 3D porous skeleton, abundant doping elements, and presence of VO_x 3D VNCN pyrolyzed at 800 °C (3D VNCN-800) ensured excellent electrochemical performance. The 3D VNCN-800 electrode exhibits a maximum specific capacitance of 408.1 F·g⁻¹ at 1 A·g⁻¹ current density and an admirable cycling stability with 96.8% capacitance retention after 5000 cycles. Moreover, an assembled symmetrical supercapacitor based on the 3D VNCN-800 electrode delivers a maximum energy density of 15.6 Wh·Kg⁻¹ at a power density of 600 W·Kg⁻¹. Our study demonstrates a potential guideline for the fabrication of porous carbon materials with 3D structure and abundant heteroatom-doping.