Monitoring the Structural Changes in Iridium Nanoparticles during Oxygen Evolution Electrocatalysis with X-ray Total Scattering.

Understanding the structure of nanoparticles under (electro)catalytic operating conditions is crucial for uncovering structure-property relationships. By combining X-ray total scattering and pair distribution function analysis with small-angle X-ray scattering (SAXS), we obtained comprehensive structural information on ultrasmall (<3 nm) iridium nanoparticles and tracked their changes during oxygen evolution reaction (OER) in acid. When subjected to electrochemical conditions at reducing potentials, the metallic Ir nanoparticles are found to be decahedral.