Asymmetric Bond Delta‐Polarization at the Interfacial Se─Ru─O Bridge for Efficient pH‐Robust Water Electrolysis

Abstract The rationalization of pH‐robust catalysis is highly desired but challengeable for overall water electrolysis (WE). It requests a metal active site that can make an efficient adaption with both cathodic hydrogen and anodic oxygen evolution reactions (HER/OER). Herein, a RuO 2‐x /RuSe 2 heterostructure electrocatalyst is profiled with interfacial Se─Ru─O bridge for the pH‐robust water splitting studies. An asymmetric bond delta‐polarization (Δp) is found at the interfacial Se─Ru─O bridge, including the Δp > 0 at the Ru─O part and Δp < 0 at the Ru─Se side by both experiment and calculation results. The enlarged Ru─O bond polarizability (Δp > 0) can in principle trigger the lattice oxygen mediated (LOM) pathway for OER; meanwhile, the reduced Ru─Se bond polarizability can benefit the HER due to the strengthened d‐p band hybridization. Resultantly, the heterostructure can deliver ultralow overpotentials of 25/10 mV for Pt‐beyond HER and 210/255 mV for OER at 10 mA cm −2 in acidic/alkaline media, respectively. In especial, the acidic overall WE can be stably operated for 200 h with a low cell voltage of 1.478 V at 10 mA cm −2 . This research clarifies the asymmetric bond polarization as the criterion for the rational design of efficient WE catalysts.