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

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journal contribution
posted on 05.01.2022, 17:07 by Abhinav S. Raman, Aleksandra Vojvodic
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.

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