Synergistic electronic interaction in RhCo catalyst regulated by vanadium–molybdenum oxide for enhanced alkaline hydrogen evolution

Abstract

Developing high-efficiency electrocatalysts for the hydrogen evolution reaction (HER) is critical for sustainable hydrogen energy. Herein, a vanadium–molybdenum oxide (HVMoO_x)-regulated RhCo catalyst (RhCoVMoO_x) was synthesized via a one-pot solvothermal method. Comprehensive physical characterizations (XRD, SEM/TEM, XPS, EPR) were conducted to analyze its crystal structure, morphology, elemental distribution, valence states and defect properties. Electrochemical tests in 1.0 M KOH showed that RhCoVMoO_x (V : Mo = 1 : 1, Co : Rh = 15 : 14) exhibited excellent HER performance (124 ± 3 mV overpotential at 10 mA cm⁻², 109.68 ± 4.2 mV dec⁻¹ Tafel slope, C_dl of 19.89 mF cm⁻², and 240-hour stability), along with good OER activity (306 ± 4 mV overpotential at 10 mA cm⁻²), demonstrating bifunctionality. Density functional theory (DFT) calculations reveal that strong orbital hybridization enhances electronic conductivity, while the optimized hydrogen adsorption free energy (ΔG_H* = 0.158 eV) approaches the ideal value, promoting favorable HER kinetics. This work offers insights into designing high-performance multi-metal electrocatalysts through electronic modulation.