Potential-Regulated Phosphate Intercalation in Defective Nickel Hydroxyphosphate for Efficient Oxygen Evolution

Controlling the transformation and structural incorporation of phosphorus-containing species is critical for regulating the structure and catalytic performance of nickel-based oxygen-evolution catalysts, yet how catalyst-growth conditions direct phosphorus species evolution and structural incorporation remains unclear. Herein, a potential-directed in-situ electrodeposition strategy is developed to regulate the evolution and incorporation behavior of phosphorus-containing species, enabling the construction of phosphate-intercalated nickel hydroxyphosphate on nickel foam (NF). Using hypophosphite as the phosphorus precursor, the deposition potential guides phosphorus-containing species toward either Ni-P formation or phosphate intercalation into the α-Ni(OH)₂ framework through modulation of the local interfacial environment. The resulting phosphate-intercalated nickel hydroxyphosphate (Ni₂(PO₄)(OH)/NF) preserves the hydroxide framework while inducing lattice expansion, local structural distortion, defect-rich transport channels, and P-O-Ni coordination interactions. These structural and electronic features facilitate the formation and stabilization of high-valence Ni oxyhydroxide active species during oxygen evolution. As a result, Ni₂(PO₄)(OH)/NF delivers an overpotential of 197 mV at 10 mA cm^-2 in 1 M KOH and sustains stable electrolysis for over 1200 h. This work establishes a potential-regulated strategy for coupling interfacial alkalization with phosphorus species transformation and phosphate intercalation, providing mechanistic guidance for constructing oxyanion-intercalated electrocatalysts for efficient oxygen evolution.