Dual modulation of electronic structure and intermediates adsorption via vanadium doping in amorphous-crystalline...

The development of active and stable bifunctional electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is highly desirable for efficient water electrolysis. Yet precise regulation of catalyst-intermediate interactions remains challenging. To address this, we fabricated vanadium-doped NiCoP nanowire arrays with amorphous-crystalline heterojunctions on nickel foam (V-NiCoP/NF) via a facile hydrothermal-phosphorization route. Systematic characterization reveals that V doping induces the formation of an amorphous CoNiPO_x phase and modulates the electronic structure, synergistically enhancing electrocatalytic activity. Density functional theory (DFT) calculations further demonstrate that V incorporation modifies the d-band center, promotes charge redistribution, and optimizes the adsorption energies of key intermediates for both HER (H₂O, H) and OER (OH, *O, *OOH). As a result, the V-NiCoP/NF electrolyzer demonstrated exceptional overall water splitting (OWS) performance, achieving a low voltage of 1.49 V at 10 mA cm^-2 and maintaining excellent stability for over 200 h. Particularly, benefiting from its unique nanoarchitecture comprising nanowire arrays, amorphous-crystalline heterojuctions and the doping effect of V, the V-NiCoP/NF electrode achieves outstanding bifunctional electrocatalytic activity, demanding low overpotentials of merely 57 mV for HER and 255 mV for OER at 10 mA cm^-2 in alkaline electrolyte. This work paves the way for the rational design of stable and highly active electrocatalysts for future energy conversion technologies.