Perspectives on the development of highly active, stable, and cost-effective OER electrocatalysts in acid

Polymer electrolyte membrane water electrolysis (PEMWE) is an attractive hydrogen energy production technology that offers various advantages such as compact design, high operating pressure, high current densities, and high hydrogen gas purity. However, PEMWE still faces several critical challenges, particularly with respect to the oxygen evolution reaction (OER) at the anode. Highly active, corrosion-resistant electrocatalytic materials are required for the acidic OER owing to its sluggish kinetics involving four-electron transfer under harsh anodic potentials. To date, IrO₂- or RuO₂-based noble metal electrocatalysts have been employed as commercial acidic OER electrocatalysts for PEMWE. However, they remain inadequate in terms of satisfying the industrial activity/stability-related requirements. Above all, the two noble metals are too rare and expensive, which significantly inhibits widespread commercialization of PEMWE. Therefore, low-cost, highly active, and highly stable OER electrocatalysts that can operate in acidic media must be urgently developed. This review paper presents various state-of-the-art strategies employed to address the aforementioned issues by classifying them according to objectives such as improving activity, enhancing stability, and reducing cost. Then, finally, we summarize major tasks and strategies to overcome them and put forward a few issues in this field.