Stability and Solvation of Key Intermediates of Oxygen Evolution on TiO2, RuO2, IrO2 (110) Surfaces: A Comparative DFT Study

Abstract Oxygen Evolution Reaction (OER) is a fundamental process, with gold standards like RuO 2 and IrO 2 . Recently, it was suggested that OER could go through unconventional intermediates, −O−H, −OO−H. −O−H is formed by the direct interaction of an adsorbed O species to a metal surface atom and a proton bound to a surface oxygen. Similarly, in −OO−H, an adsorbed −OO adduct interacts with a proton on a surface oxygen. This work compares the nature of key intermediates of OER on TiO 2 , RuO 2 , and IrO 2 (110) surfaces by Density Functional Theory (DFT) calculations and Ab‐Initio Molecular Dynamics (AIMD). We rationalized the nature, the relative stability trends in vacuum and the effect of water solvation of the species. −OO−H is preferred than −OOH. −OH is preferred than −O−H except for RuO 2 . We investigated the nature of the catalyst/water interfaces and the interaction of intermediates with water based on AIMD. On RuO 2 , −OH and −O−H display a different interaction with water. −OO−H is quite rigid on RuO 2 , while it is dynamic on IrO 2 as the proton is shared between −OO and a surface oxygen atom. This study provides insights on the role of solvation to the nature of OER intermediates, that may help future studies.