N, P Codoped CoMoO₄ Nanowire Arrays: Enhanced Water-Splitting Performance and Dynamic Reconstruction Mechanism

Developing efficient and stable nonprecious metal bifunctional electrocatalysts remains one of the key challenges in achieving low-cost water splitting for hydrogen production. Cobalt molybdate (CoMoO₄) has attracted considerable attention due to its promising catalytic activity; however, its inherent hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance still require significant improvement. Elemental doping is a widely used strategy to regulate the electronic structure and surface properties of catalysts. Nevertheless, the structural evolution of N/P-doped CoMoO₄-based catalysts during the HER and OER processes, as well as the underlying mechanisms linking this evolution to catalytic performance, remain unclear. This work aims to elucidate the effects of nitrogen (N) and phosphorus (P) codoping on the HER and OER activities of CoMoO₄ catalysts and to investigate their dynamic reconstruction mechanisms under electrocatalytic conditions. Electrochemical testing indicates that NP_CoMoO₄ exhibits optimal performance in the HER, featuring the lowest overpotential (161 mV at 10 mA cm^-2), the lowest charge-transfer resistance, and excellent stability. Phosphorus doping significantly enhances oxygen evolution activity, with P_CoMoO₄ demonstrating an overpotential of only 377 mV at 100 mA cm^-2. Density functional theory calculations confirm that codoping with N and P eliminates the band gap near the Fermi level in CoMoO₄, thereby enhancing electron conduction and HER activity. Conversely, P doping improves conductivity while maintaining structural stability, which benefits the OER. Overall, this study elucidates the mechanism by which nonmetallic doping regulates the restructuring behavior and catalytic performance of CoMoO₄, offering a novel strategy for designing highly efficient bifunctional electrocatalysts for water splitting.