A Cu doped RuO 2 catalyst for efficient and durable acidic water oxidation

Abstract Producing hydrogen by water electrolysis in acidic system is essential for advancing the proton‐exchange membrane water electrolyzer (PEMWE) and maintaining the global sustainability. However, excavating highly active and durable catalysts for anodic oxygen evolution reaction (OER) in acid medium remains a great challenge due to the sluggish kinetics of OER and the severe catalyst dissolution. In this work, we developed a Cu doped RuO 2 catalyst (Cu‐RuO 2 @CP) through simple drop casting and low temperature pyrolysis procedures. The incorporation of Cu into RuO 2 executes complicated responsibilities: improving OER activity by raising more oxygen vacancies and accelerating the charge transfer between solid‐liquid interface; strengthening the long‐term durability via suppressing the over‐oxidation of RuO 2 into soluble RuO 4 ; lowering the catalyst cost by replacing with less expensive Cu. Hence, the Cu‐RuO 2 @CP exhibits excellent activity and stability in 0.5 M H 2 SO 4 electrolyte, requiring a low overpotential of 200 mV to achieve 10 mA cm −2 and preserving stability for almost 500 h. Moreover, the overpotential is as low as 397 mV even when operating under an industrial‐level current density of 1000 mA cm −2 , paving a new way to develop high performance OER electrocatalyst in acidic environment to promote the large‐scale utilization of PEMWE.