Hollow Nickel-Cobalt-Iron Phosphide Nanoprisms for Efficient Oxygen Evolution

Developing efficient electrocatalysts for the oxygen evolution reaction (OER) is essential for sustainable water electrolysis. Herein, a hollow trimetallic phosphide catalyst (NiCoFe-P) was synthesized from Prussian blue analog nanoprisms through a self-templated etching process followed by gas-phase phosphorization. The resulting hierarchical hollow architecture with uniformly distributed Ni, Co, Fe, and P species provides abundant active sites and facilitates efficient mass and charge transport. The catalyst exhibited excellent OER performance in alkaline electrolyte, delivering a low overpotential of 274 mV at 10 mA cm^-2, a small Tafel slope of ≈51 mV dec^-1, and outstanding durability over 100 h. Density functional theory calculations combined with operando Raman spectroscopy reveal that optimized Fe─O electronic coupling facilitates the formation of oxygen intermediates, thereby enhancing OER kinetics.