Thermodynamic and kinetic analysis of the oxygen evolution reaction on TiO2 (100) and (101) surfaces: A DFT study

Abstract

The search for alternative energy sources with sustained economic viability and minimal pollution is imperative, making hydrogen a promising candidate as a fuel. This work provides important findings on the Oxygen Evolution Reactions (OER) on TiO₂, with a focus on elucidating the reaction mechanisms. Density Functional Theory calculations were applied on both the (101) and (100) surfaces of the catalyst. The application of overpotentials was evaluated, with 2.85 and 2.32 eV required for (101) and (100) surface, respectively, for all reaction steps to be exergonic. The 0.53 eV difference suggests a potentially favorable pathway for the OER on the (100) surface. When evaluating the kinetics, an additional barrier of 2.84 eV under the $U=0.00$ V condition on the (100) surface is found for the formation of the OOH intermediate, suggesting the kinetics preference for the oxygen evolution process on the (101) surface.