Providing Atomistic Insights into the Dissolution of Rutile Oxides in Electrocatalytic Water Splitting

The stability and dissolution of rutile oxides such as RuO₂ and IrO₂ which are used as electrocatalysts for water splitting have long been the Achilles’ heel in the long-term operation of electrolyzers for sustainable production of hydrogen from water. In this study, using a combination of ab initio steered molecular dynamics, enhanced sampling, and ab initio thermodynamics, we investigate the surface stability and dissolution of three prominent electro­(photo)­catalysts for water splitting: RuO₂, IrO₂, and TiO₂ in the rutile phase. We provide an atomistic understanding of the dissolution process and establish possible dissolution paths for different oxides using the (110) surface as a prototype. Interestingly, we identify a distinct surface site specificity in the dissolution of the RuO₂(110) surface, with the coordinately undersaturated sites more prone to dissolution, whereas no such surface site specificity exists for the IrO₂(110) surface. In addition, our investigation of more complex dissolution mechanisms involving codissolution of the different surface sites on the RuO₂(110) surface reveals a hitherto unseen suppression of the dissolution of Ru from the bridge sites caused by the codissolving coordinately undersaturated sites. These findings provide routes to improving the stability and a path toward understanding the activity–stability conundrum in electrocatalytic water splitting.