Ni/WC-Mo₂C ternary-interface electrocatalyst for bidirectional optimization of HER and OER

Developing efficient bifunctional electrocatalysts for water splitting remains challenging due to the antagonistic demands of oxygen and hydrogen evolution reactions (OER/HER). Herein, we present a ternary heterointerface non-precious catalyst, Ni/WC-Mo₂C, for bidirectional HER and OER optimization. Combining in situ characterization and theoretical calculations, we demonstrate how this design overcomes conventional Schottky junction limitations: (i) The band gradient of the WC-Mo₂C semiconductor heterojunction synergizes with metallic Ni's electron-donating properties to construct an “electron staircase” channel to enhance charge transfer while increasing active electron density and lowering the D-band center; and (ii) ternary interface-induced lattice strain buffering and localized electron redistribution stabilize high-valent Ni species and optimize intermediate adsorption/desorption energetics. This synergy resolves the OER-HER electronic conflict, endowing the catalyst with ultralow overpotentials of merely 26 mV for HER and 153 mV for OER at a current density of 10 mA cm ⁻² in 1.0 M KOH electrolyte. The assembled electrolyzer delivers a high current density of 1000 mA cm⁻² at a low cell voltage of 1.73 V and sustains stable overall water splitting operation for an extended duration of 1200 h, outperforming noble-metal benchmarks (Pt/C||RuO₂). This work establishes a new paradigm for non-precious bifunctional electrocatalyst design through multicomponent heterointerface engineering.