Direct observation of structural disorder effects on iridium dioxide nanocrystal dissolution

The current state-of-the-art electrocatalyst for the oxygen evolution reaction (OER) is iridium dioxide, providing a compromise between activity and stability. The low elemental abundance of iridium, coupled with the dissolution of iridium dioxide under operating conditions, prevents the global-scale implementation of electrolyzers. Understanding the origin of iridium dioxide dissolution at the nanoscale is crucial for the development of next-generation electrocatalysts that efficiently utilize iridium to meet energy demands. Herein, we report the influence of structural disorder, modulated by synthesis temperature, on the nanoscale dissolution dynamics and electrocatalytic activity of iridium dioxide nanocrystals. Our observations of dissolution on single nanocrystals revealed that structural disorder destabilized the OER-inactive (111) facets and had no substantial effect on the stability of the OER-active (110) facets. These findings highlight the importance of understanding nanoscale dynamic restructuring and suggest the possibility of developing highly active and stable (110)-based iridium dioxide electrocatalysts for water oxidation.