Heteroatom dopants overcome the activity-stability trade-off in RuO2 for acidic oxygen evolution

Abstract

The pursuit of RuO2 as an alternative acidic oxygen evolution reaction electrocatalyst to IrO2 holds great promise, yet simultaneously achieving highly active and stable RuO2 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 RuO2 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-RuO2 exhibits a low overpotential of 170 mV at 10 mA cm−2, a favorable Tafel slope of 44 mV dec−1, and an outstanding durability. We demonstrate that proton-exchange membrane water electrolyzers equipped with Ta/B-RuO2 achieves a current density of 1.0 A cm−2 at a low voltage of 1.6 V and maintains stable operation for 120 h at 200 mA cm−2. An efficient and durable alternative catalyst to iridium oxide is essential for acidic oxygen evolution. Here, the authors report a catalyst based on RuO2 co-doped with tantalum and boron, creating Ru-O-Ta frameworks and Ru-O-B active sites that stabilize the catalyst and enhance performance.