In Situ X-ray Spectroscopy of the Electrochemical Development of Iridium Nanoparticles in Confined Electrolyte

Abstract

Iridium oxide-based catalysts are uniquely active and stable in the oxygen evolution reaction. Theoretical work attributes their activity to oxyl or mu(1)-O species. Verifying this intermediate experimentally has, however, been challenging. In the present study, these challenges were overcome by combining theory with new experimental strategies. Ab initio molecular dynamics of the solid-liquid interface were used to predict spectroscopic features, whereas sample architecture, developed for surface-sensitive X-ray spectroscopy of electrocatalysts in confined liquid, was used to search for these species under realistic conditions. Through this approach, we have identified mu(1)-O species during oxygen evolution. Potentiodynamic X-ray absorption additionally shows that these mu(1)-O species are created by electrochemical oxidation currents in a deprotonation reaction.