Strontium-doped RuO2 electrocatalyst with abundant oxygen vacancies for boosting OER performance†

The oxygen evolution reaction (OER) plays a crucial role as the anode reaction of electrolytic water splitting in various applications. To date, it is still a great challenge to develop highly active and durable electrocatalysts for acidic electrolytic water splitting. Herein, we highlight an effective strategy to regulate the oxidation state of Ru species and oxygen vacancies in RuO₂ by introducing Sr heteroatoms into its lattice based on the principle of charge equilibrium. The as-prepared Sr_0.1RuO_x catalyst exhibits excellent OER activity with an overpotential of 201 mV at a current density of 10 mA cm⁻², which is attributed to the higher proportion of Ru⁴⁺ induced by Sr doping. Moreover, both experimental and theoretical calculations revealed that the introduced oxygen vacancies inhibited the overoxidation of Ru to Ru^n>4+ during the OER process, thus enhancing the stability of Sr_0.1RuO_x. Therefore, the PEM electrolyzer using Sr_0.1RuO_x as the anode catalyst can be operated for 240 hours at 10 mA cm⁻² without obvious attenuation. This work presents an effective strategy to regulate the structure of OER electrocatalysts with excellent performance.