Balancing Ru–O bond covalency and strength via atomic Ta doping for robust acidic oxygen evolution

Atomic Ta doping via a molten-salt route forms asymmetric Ta–O–Ru active sites that optimize Ru–O covalency and reinforce the Ta–O–Ru linkage, enabling RuO x –10Ta to achieve 189 mV at 10 mA cm −2 and >700 h stability of acidic OER.