1. Joint Center for Artificial Photosynthesis (JCAP) Energy Innovation Hub, LBNL, 1 Cyclotron Road, MS 976‐JCAP, Berkeley, CA 94720 (USA);2. SLAC National Accelerator Laboratory, 2575 Sand Hill Rd, Menlo Park, CA 94025 (USA)
Abstract:
An iridium oxide nanoparticle electrocatalyst under oxygen evolution reaction conditions was probed in situ by ambient‐pressure X‐ray photoelectron spectroscopy. Under OER conditions, iridium undergoes a change in oxidation state from IrIV to IrV that takes place predominantly at the surface of the catalyst. The chemical change in iridium is coupled to a decrease in surface hydroxide, providing experimental evidence which strongly suggests that the oxygen evolution reaction on iridium oxide occurs through an OOH‐mediated deprotonation mechanism.