Oxygen adsorption on the Ag/La1−xSrxMnO3(0 0 1) catalysts surfaces: A first-principles study

The oxygen adsorption on Ag/LSM(0 0 1) catalysts surfaces has been investigated using first-principles density functional theory calculations. The most favorable oxygen adsorption sites are found to be atop surface Mn atoms on the MnO2-terminated surface and on the hollow positions of the La(Sr)O-terminated LSM(0 0 1) surface. The calculated adsorption energies for Ag atom demonstrate that the Ag adsorption at O site is much more favorable than Mn site. The atomic relaxation results indicate that Ag doping produces a strong local perturbation and a large effect on the surface properties. No significant improvement for oxygen adsorption is found due to Ag doping. However, the O2 adsorption energy increases from 0.495 eV to 0.937 eV due to the pre-adsorbed Ag. It is pre-adsorbed Ag that facilitates O2 adsorption on surface. The bond length and bond population of O2 molecule indicate that Ag atom facilitates O2 molecule dissociative adsorption. The adsorbed Ag on LSM strengthens its activity as SOFCs cathode by acting as an active center at the surface.

► The catalytic role of Ag in the oxygen adsorption of La1−xSrxMnO3(0 0 1) surface.
► The Ag doping produces a strong local perturbation.
► Ag adsorption at O site is much more favorable than Mn site.
► Ag atom facilitates O2 molecule dissociative adsorption.