Theoretical study on the effect of an O vacancy on the hydrogen storage properties of the LaFeO_3 (010) surface

摘要

Based on first-principles calculations, we investigated the hydrogen adsorption dissociation on the LaFeO3 (010) surface with an 0 vacancy. It was confirmed that H-2 molecules have four kinds of adsorption modes on LaFeO3 (010) surfaces with an 0 vacancy. First, H atoms are adsorbed on O atoms to form an -OH group. Second, H atoms are adsorbed on Fe atoms to form Fe H bonds. Third, two H atoms are adsorbed on the same O atom to form H2O. Fourth, two H atoms are adsorbed on the same Fe atom and it is a new type of adsorption, which does not exist in the ideal surface. The main channel of dissociative adsorption is the fourth adsorption mode of OH and Fe-H, where the H atoms adsorbed on the surface of Fe can be easily diffused into O atoms. Charge population analysis showed that increasing the O vacancy enhanced the interaction between Fe-H. In the system containing O vacancies adsorbed H atoms in the top of Fe to diffuse to the top of O need to overcome the energy barrier decreased from 0.968 eV to 0.794 eV. So the existence of an O vacancy enhances the hydrogen absorption properties of Fe atoms in LaFeO3. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.