Ab Initio Simulation Explains the Enhancement of Catalytic Oxygen Evolution on CaMnO3

Experimental results have shown promising catalytic activity for the oxygen evolution reaction (OER) on the perovskite-type material CaMnO3. Through density functional theory investigations, we study the OER mechanism on CaMnO3, on the basis of a thermodynamic stability approach. Our results reveal that the formation of Mn vacancies caused by the solubility of Mn enhances lattice oxygen activity, which then reduces the energy of the adsorbate *OOH and therefore loosens the lower overpotential limit predicted from the scaling relationship. This effect suggests that, by doping manganite oxides with soluble elements, we could enhance their OER catalytic activities due to the high surface lattice oxygen activity induced by surface metal ion vacancies.