The adsorption and diffusion theoretical investigations of H on LaFeO3(010) surface with an O vacancy

Abstract

Based on the first-principles method of density functional theory and the transition state theory, the adsorption, occupancy and diffusion behaviors of H atoms in LaFeO3(010) surface with O vacancy are investigated. It is found that, for the LaFeO3(010) surface with O vacancy, the H atom prefers to adsorb on the O atom and also could adsorb on the Fe atom; the adsorption energy of H atom in the surface layer is the biggest, while the adsorption energy decreases with the H atom in-depth diffusion to the bulk; the diffusion of H atoms from the surface layer to the bulk phase is a process of progressive rotation around the O atom, and the stepwise diffusion is more likely to occur than the direct diffusion. If the H atom can cross the barrier and diffuse from the surface to the subsurface, it will be more likely to diffuse inward. The presence of O vacancy can reduce the barrier for H atoms diffusion from the surface to the subsurface, and then improve the diffusion properties of the LaFeO3(010) surface system.