Incorporating Cu oxides with IrO2 for improving the stability of the oxygen evolution reaction in neutral and alkaline conditions

Developing highly efficient and stable electrocatalysts for the oxygen evolution reaction (OER) remains a major challenge, especially under different pH conditions. IrO₂ is renowned as one of the most efficient electrocatalysts for the OER, but it tends to degrade at high current densities. In general, incorporating secondary metals into primary catalysts has proven to be an effective way to enhance the electrocatalytic performance for water splitting. In this work, we present an electrochemically synthesized bimetallic Cu–IrO₂ electrocatalyst that demonstrates enhanced activity and stability for the OER compared to IrO₂ alone. In alkaline media, Cu–IrO₂ annealed at 300°C demonstrated an onset potential of 1.40 V vs RHE and a low Tafel slope of 46 mV dec^–1. The combination of Cu addition, in the form of Cu oxides, and heat treatment increased catalyst durability with minimal degradation over 80 h of testing under on–off electrolysis conditions. Similar enhancements were also found under neutral pH conditions. The improved activity of Cu oxide–incorporated IrO₂ is attributed to increased electrochemically active surface and low resistance to charge transfer while the improved durability is attributed to maintaining the structural and crystalline integrity of the catalyst during the OER.