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 RuO2 and IrO2. 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 bound to a surface oxygen. This work compares the nature of key intermediates of OER on TiO2, RuO2, and IrO2(110) surfaces by Density Functional Theory (DFT) calculations and Ab‐Initio Molecular Dynamics (AIMD). We rationalized the nature, the relative stability trends in vacuum, the effect of water solvation of the species. ‐OO‐H is preferred than ‐OOH. ‐OH is preferred than ‐O‐H except for RuO2. We investigated the nature of the catalyst/water interfaces and the interaction of intermediates with water based on AIMD. On RuO2, ‐OH and ‐O‐H display a different interaction with water. ‐OO‐H is quite rigid on RuO2, while it is dynamic on IrO2 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.