The comparative theoretical study of the LaBO3 (001) (B = Mn, Fe, Co, and Ni) surface properties and oxygen adsorption mechanisms

In this paper, the surface properties of the (001) surface LaBO3 (B = Mn, Fe, Co, and Ni) perovskites and oxygen adsorption mechanism are investigated using first-principles calculations based on density functional theory (DFT) and pseudopotential method. Surface rumpling and Mulliken effective atomic charges have been obtained. The surface rumpling displays a big wave and increases following the sequence Fe < Co < Mn < Ni at the BO2-terminated surface. The calculated effective charges show that the excess electronic charges at the LaO-terminated surface transfer to the inner atom of the surface. We also report a comparative study of oxygen molecular adsorption properties at BO2- and LaO-terminated surfaces of LaBO3 (001). The optimized geometries of the adsorbed oxygen species, adsorption energies, bond lengths, bond populations, and effective charges have been analyzed. The results show the oxygen molecule adsorption at the hollow site of the LaO-terminated surface has much higher adsorption energy and dissociation probability than that at other sites. Oxygen species has a strong tendency for getting adsorbed at the site and thereby filling it. The comparative study of the LaBO3 (001) surface properties and oxygen adsorption mechanism may guide us to search for high-efficiency cathode materials for solid oxide fuel cells (SOFC).