First-Principles Modeling of Oxygen Adsorption on Ag-Doped LaMnO3 (001) Surface

Abstract

The density functional theory (DFT) method has been used to calculate oxygen adsorption on the Ag-doped MnO2- and LaO-terminated (001) LaMnO3 surfaces. The catalytic effect of Ag doping is revealed by comparison of the adsorption energies, electron charge redistribution, and interatomic distances for the doped and undoped surfaces. Adsorption of Ag on the MnO2-terminated surface increases the adsorption energy for both atomic and molecular oxygen. This increases the oxygen surface concentrations and could improve the cathode efficiency of fuel cells. The opposite effect takes place at the LaO-terminated surface. Due to the large adsorption energies, adsorbed oxygen atoms are immobile and the oxygen reduction reaction rate is controlled by the concentration and mobility of oxygen vacancies.