Mo-Engineered O ads –Co 3 O 4 Interfaces via Electrochemical Reconstruction for Enhanced Methanol Oxidation and Hydrogen Evolution

Developing cost-effective and durable bifunctional electrocatalysts for methanol-assisted water electrolysis is crucial, yet it remains a critical challenge for sustainable hydrogen production. Herein, we report the electrochemical reconstruction of hydrothermally derived CoMoO 4 grown on nickel foam (NF) into oxygen-adsorbed Co 3 O 4 nanosheet arrays (O ads –Co 3 O 4 /NF). The reconstruction process involves progressive Mo dissolution and oxygen-vacancy filling, leading to a stabilized surface enriched with Co 3+ species and absorbed oxygen. The resulting hierarchical nanosheet architecture supported on porous NF provides abundant accessible active sites and promotes efficient mass and charge transport. Benefiting from these structural and electronic advantages, the optimized catalyst delivers 100 mA cm –2 at only 1.32 V (vs reversible hydrogen electrode) for the methanol oxidation reaction, achieving a high Faradaic efficiency of 98.89% toward formate, and exhibits efficient hydrogen evolution activity with an overpotential of 250 mV at 100 mA cm –2 . When integrated into a two-electrode methanol-assisted electrolyzer, the system requires only 1.63 V to reach 100 mA cm –2, corresponding to a reduction of 310 mV compared with conventional water electrolysis. Density functional theory calculations reveal that the reconstruction-induced upshift of the d-band center optimizes methanol adsorption (−1.03 eV) and hydrogen intermediate binding (−0.15 eV), accounting for the enhanced bifunctional activity. This work provides insights into the rational design of high-performance nonprecious metal bifunctional electrocatalysts for energy conversion applications.