Interface charge engineering of ternary RuCoMo oxide nanofibers toward high-current-density water electrolysis

The efficacy of RuO₂ as a bifunctional electrocatalyst for alkaline water electrolysis is usually constrained by its sluggish hydrogen evolution kinetics and poor stability. Herein, we report the fabrication of ternary RuCoMoO _x nanofibers (NFs) incorporating oxide heterojunctions, which address these issues through interfacial charge engineering. The electron redistribution induced by the constructed interface optimizes the local electronic environment, endowing the catalyst with superior activity and stability for both the hydrogen and oxygen evolution reactions (HER/OER). The RuCoMoO _x NFs require ultralow overpotentials of 274.8 mV for the HER and 367.9 mV for the OER to deliver a high current density of 1 A cm^-2, surpassing commercial Pt/C and RuO₂ benchmarks. Moreover, the catalyst possesses superior operational stability for both the HER and the OER at 1 A cm^-2 compared to Pt/C and RuO₂, respectively. In a practical electrolyzer, the assembled symmetric RuCoMoO _x NFs‖RuCoMoO _x NFs system delivers a much lower working voltage than Pt/C‖RuO₂ and maintains stable operation at 1 A cm^-2 for 60 h. This work validates interfacial charge engineering as a key strategy for creating high-performance noble-metal-lean electrocatalysts for industrial water electrolysis.