Coupling the vanadium-induced amorphous/crystalline NiFe2O4 with phosphide heterojunction toward active oxygen evolution reaction catalysts

Developing efficient and robust electrocatalysts is increasingly essential for water splitting, severely hindered by the sluggish four-electron transfer process of oxygen evolution reaction (OER). Amorphous/crystalline heterophase engineering has recently emerged as a promising electronic modulation approach for OER catalysts but suffers from poor conductivity of the amorphous structure. Here, we coupled the amorphous/crystalline NiFe2O4 induced by vanadium doping with NiP heterojunction, highlighting the synergistic effect in modulating the electronic structures and the complementary effect in promoting conductivity. As a superior electrocatalyst to commercial RuO2, the as-prepared NFO-V0.3-P showed a low overpotential of 277 mV at the current density of 20 mA cm−2, a Tafel slope of 45 mV dec−1, and long-term stability. The excellent OER catalytic activity is attributed to the synergistic effect at the heterophase interface with rich active sites, fine-tuning of electronic regulation, and enhanced conductivity.