Enhanced Acidic Oxygen Evolution Reaction Performance by Anchoring Iridium Oxide Nanoparticles on CoO.

The sluggish kinetics of the anodic process, known as the oxygen evolution reaction (OER), has posed a significant challenge for the practical application of proton exchange membrane water electrolyzers in industrial settings. This study introduces a high-performance OER catalyst by anchoring iridium oxide nanoparticles (IrO) onto a cobalt oxide (CoO) substrate via a two-step combustion method. The resulting IrO@CoO catalyst demonstrates a significant enhancement in both catalytic activity and stability in acidic environments. Notably, the overpotential required to attain a current density of 10 mA cm, a commonly used benchmark for comparison, is merely 301 mV. Furthermore, stability is maintained over a duration of 80 h, as confirmed by the minimal rise in overpotential. Energy spectrum characterizations and experimental results reveal that the generation of OER-active Ir species on the IrO@CoO surface is induced by the strong interaction between IrO and CoO. Theoretical calculations further indicate that IrO sites loaded onto CoO have a lower energy barrier for *OOH deprotonation to form desorbed O. Moreover, this interaction also stabilizes the iridium active sites by maintaining their chemical state, leading to superior long-term stability. These insights could significantly impact the strategies for designing and synthesizing more efficient OER electrocatalysts for broader industrial application.