Orbital Hybridization Engineering of Mo-Doped Co₂P Nanoarrays as Bifunctional Catalysts for Energy-Saving...

Urea-assisted electrolysis is a promising strategy for energy-efficient hydrogen production by replacing the oxygen evolution reaction (OER) with the thermodynamically favorable urea oxidation reaction (UOR). However, the sluggish UOR kinetics and the demand for efficient hydrogen evolution (HER) require highly active bifunctional catalysts. Herein, vertically aligned Mo-doped Co₂P (Mo-Co₂P) nanoarrays supported on nickel foam are constructed via a metal-organic framework (MOF)-derived strategy. Mo incorporation induces electronic redistribution, downshifting the Co d-band center and weakening d-p orbital hybridization, thereby reducing Co-P bond covalency and optimizing the hydrogen adsorption free energy to 0.15 eV. Under anodic conditions, the surface reconstructs into active oxyhydroxide phases, while Mo promotes urea adsorption and activation. Consequently, Mo-Co₂P achieves excellent bifunctional activity, requiring only -52 mV for HER and 1.359 V for UOR to reach 10 mA cm^-2. The assembled urea-assisted electrolyzer delivers 10 mA cm^-2 at a low cell voltage of 1.429 V, with a 13.2% lower energy consumption than conventional water electrolysis. This work highlights orbital hybridization and bond covalency engineering for developing advanced bifunctional catalysts.