Heteroatom dopants overcome the activity-stability trade-off in RuO for acidic oxygen evolution.

The pursuit of RuO as an alternative acidic oxygen evolution reaction electrocatalyst to IrO holds great promise, yet simultaneously achieving highly active and stable RuO remains an urgent challenge, as conventional strategies often boost one property at the expense of the other. Here, we successfully construct Ta and B co-doped nanoporous RuO with Ru-O-Ta frameworks and Ru-O-B active sites to overcome the activity-stability trade-off. The Ru-O-Ta frameworks stabilize the Ru sites by mediating bridging oxygen and preferentially replenishing oxygen vacancies, thereby facilitating the oxygen evolution reaction through the adsorbate evolution mechanism. Concurrently, the Ru-O-Ta/B sites not only switch the rate-determining step but also lower the energy barriers, thereby enhancing catalytic activity. The Ta/B-RuO exhibits a low overpotential of 170 mV at 10 mA cm, a favorable Tafel slope of 44 mV dec, and an outstanding durability. We demonstrate that proton-exchange membrane water electrolyzers equipped with Ta/B-RuO achieves a current density of 1.0 A cm at a low voltage of 1.6 V and maintains stable operation for 120 h at 200 mA cm.