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 RuO2-x/RuSe2 heterostructure electrocatalyst is profiled with interfacial Se & horbar;Ru & horbar;O bridge for the pH-robust water splitting studies. An asymmetric bond delta-polarization (Delta p) is found at the interfacial Se & horbar;Ru & horbar;O bridge, including the Delta p > 0 at the Ru & horbar;O part and Delta p < 0 at the Ru & horbar;Se side by both experiment and calculation results. The enlarged Ru & horbar;O bond polarizability (Delta p > 0) can in principle trigger the lattice oxygen mediated (LOM) pathway for OER; meanwhile, the reduced Ru & horbar;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.