Ir-RuO_x Nanoparticles on WO₃ Ultrafine Nanowires As Catalysts for the Oxygen Evolution Reaction in Acidic Media

Iridium- and ruthenium-based materials show high activity for oxygen evolution reaction (OER) in acidic media while Ru-based catalysts exhibit low stability, but Ir-based materials are limited by their high cost and low reserves. The rational design of the OER electrocatalysts to balance activity, stability, and cost is facing a challenge. Herein, we report a strategy to synthesize Ir-RuO x @WO 3 catalyst using a low-temperature wet reflux method to deposit Ir-RuO x nanoparticles on ultrafine WO 3 nanowires. Due to the metal–metal support interaction (MMSI) between Ir-RuO x and WO 3, the abundant hydroxyl groups on the surface, and the protection of active sites by the mild catalyst synthesis method, Ir-RuO x @WO 3 demonstrates the OER activity with a low overpotential of 148 mV at 10 mA/cm 2 while the total precious metal usage is only 7.673 wt % (2.990 wt % Ir and 4.647 wt % Ru). Besides, with Ru activating the valence state of Ir to improve the activity and Ir stabilizing the Ru site to improve the stability, Ir-RuO x @WO 3 achieved relative activity-stability balance as there was no noticeable degradation when operating at 10 mA/cm 2 for 12 h. This study presents design concepts of acidic OER catalysts to balance activity, stability, and cost, promoting the widespread use of PEMWE technology in industrial settings.