Enhancing the electrocatalytic oxygen evolution performance of iridium oxide in acidic media by inducing a lower valence state using CeO2 support

In this study, a composite catalyst consisting of IrOx nanoparticles dispersed in CeO2 support (IrOx/CeO2) was prepared for oxygen evolution reaction (OER) using a simple polyol method. The oxygen transfer from IrOx to oxygen defects in CeO2 induced a high ratio of lower-valence Ir3+ species, which are known to be an active phase for OER. The prepared IrOx/CeO2 catalyst exhibited excellent OER performance with a small overpotential of 263.4 mV at 10 mA/cm2, and good stability for 10 h under acidic condition, outperforming IrOx/C and commercial IrO2 catalysts. The lower-valence Ir3+ species near the catalyst surface functioned as possible active site ensembles, promoting the chemical and electrochemical steps during OER process and improving the OER activity. Additionally, the metal-support interaction between IrOx and CeO2 enhanced the durability of the catalyst.