First-principles study of oxygen evolution on Co3O4 with short-range ordered Ir doping

Abstract

The large overpotential of oxygen evolution reaction (OER) in water-splitting process prevented its application in energy field, researchers attempted to find efficient catalysts. Here, we used short-range ordered Ir-doped Co3O4 (100) model to study the OER performance under various coordination conditions through first-principles calculations. This doping pattern enabled the model to display three types of active sites, included single Ir/Co site and double Ir sites, which were different in terms of propensity to adsorb reaction intermediates. The OER performance of three types of active sites with the same O and OH coverage was evaluated, we found that O covered surface increased OER catalytic activity for single Ir/Co site. While for double Ir sites, it exhibited the lowest overpotential among the above three types, and O/OH coverage had a little influence on its activity. Furthermore, Bader charge and partial density of states analyses showed that, for single Ir/Co site, the overpotential on covered surface was reduced due to the valence electrons decrease at the metal site. While for double Ir sites, the overpotential reduction was due to the unique adsorption patterns. Additionally, the solvation effect was considered. It was found that the solvation had a key effect on the adsorption energy depending on the binding site of the intermediate. But the overpotential trend in solvent was similar with that in vacuum on the same active site.