Adsorption and diffusion mechanism of hydrogen atom on the Li2O (111) and (110) surfaces from first principles calculations

Abstract

The adsorption and diffusion of H atoms on (111) and (110) surfaces of Li2O lithium ceramics were investigated by the first principles method based on the density functional theory. The formation energies of these two surfaces were 0.546 J/m2 and 0.781 J/m2, respectively, which are a little smaller than those obtained by others. Combined with the adsorption energy, local electronic density of states, Bader charge analysis and charge density, we found that H atoms have three kinds of adsorption type on these two surfaces: physical adsorption, weak chemisorption and chemisorption. Comparing the diffusion barrier of H atoms on two surfaces, it is found that H atoms need to overcome over a barrier about 1.0 eV from top O atom to bridge site of two top Li atoms on (111) surface by CI-NEB. It is easier for the H atom to diffuse on the (110) surface with the diffusion barrier not to exceed 1.0 eV.