The electronic properties and structural stability of LaFeO3 oxide by niobium doping: A density functional theory study

The niobium doping perovskite has been used in anode materials of solid oxide fuel cell. The electronic properties and structural stability of LaFeO3 (LFO) oxide by Nb-doping and the adsorption of H2 molecule at the clean and Nb-doped LFO (001) surface are investigated by theoretical calculations. The calculated results reveal that the band gap of the orthorhombic LFO is 2.04 eV and the gap disappears after the Nb-doping, which improves the electrical conductivity. The Nb-doping increases the formation energy of oxygen vacancy in orthorhombic LFO. The calculated results of binding energy and formation enthalpy imply that the structural stability is strengthened after Nb-doping, which provides a theoretical explanation for recent experimental observations. This result can be attributed to the change of electronic structure after the Nb-doping. The bond mechanisms for LFO and Nb-doped LFO are obtained by analyzing density of states, Mulliken charges and bond population. Based on adsorption properties, it can be found that the adsorption of H2 molecule is slightly enhanced after Nb-doping and the Nb-doping facilitates that H2 molecule dissociates to H atoms. These results could provide powerful interpretations for the origin of experimental phenomenon.