First-principles study on the catalytic role of Ag in the oxygen adsorption of LaMnO_3(001) surface

摘要

In the present paper, the catalytic role of Ag in the oxygen adsorption of LaMnO_3(001) surface has been theoretically investigated using first-principles calculations based on the density functional theory (DFT) and pseudopotential method. The O_2 adsorption energy is larger for the vertical adsorption and the covalent bond was formed between O_2 molecule and surface Mn. The calculation of electronic properties of interaction between Ag atom and LaMnO_3(001) surface demonstrates that the most stable position for Ag adsorption is hollow site. The O_2 adsorption energy dramatically increased from 0.298 eV to 1.108 eV due to Ag pre-adsorbed. It is Ag pre-adsorbed that facilitates O_2 adsorption on surface. The bond length and bond population of O_2 molecule indicate that Ag atom facilitates O_2 molecule dissociative adsorption. The Ag atom strengthens LaMnO_3(001) substrate activity and activity center was formed on surface, which enhances the electrocatalytic activity of LaMnO_3 as solid oxide fuel cells cathode material at low temperature.