4:00 PM - 6:00 PM
[15p-P15-8] First-Principles Calculations of Nitric Oxide Adsorption and Its Magnetism on the FeO2 Terminated LaFeO3 (001) Surface: Oxygen Vacancy Effects
Keywords:surface, First-Principles calculation, oxide
Perovskite catalysts are attracting enormous attention since they utilized especially as automotive emissions catalysts. At low temperatures, within a short time from ignition of automotive engines, the reduction mechanism of nitrogen oxides (NOX) does not work well except in case of the Rh-doped catalyst with enhanced reactivity, so that nitric oxide (NO) adsorption is studied via DFT study. However, as far as we know, there are no discussions on its magnetism.
In this study, we evaluate adsorption energy of the NO molecule, Eads = E(slab-NO) - E(slab) - E(NO), on the FeO2 terminated LaFeO3 (001) surface with and without oxygen vacancies (VO). The plane-wave pseudo-potential density functional theory method as implemented in the Quantum-ESPRESSO package was used throughout the calculations[1]. The Perdew-Burke-Ernzerhof-Generalized Gradient approximation (PBE-GGA) was employed for the exchange-correlation functional.
As a result, on a clean surface of the LaFeO3 slab, the system realizes G-type antiferromagnetic ordering and high-spin configurations. Also, the Eads is evaluated around -1 eV, resulting in a tendency of NO adsorption. In case of a surface slab with VO of 25 at% with respect to the surface O in 1st FeO2 layer, the value is evaluated to be -1.35 eV close to that without VO, forming a bond between nitrogen of adsorbed NO with Fe in the 1st layer with the VO. In case of a surface slab with VO of 50 at% in the 1st FeO2 layer as shown in the figure, the value is evaluated to be -2.17 eV, leading to the enhancement of adsorption energy. We find strong anti-parallel spin coupling between the adsorbed NO and the Fe. We also find that formation of donor states due to the surface VO enhances the adsorption energy of NO.
In this study, we evaluate adsorption energy of the NO molecule, Eads = E(slab-NO) - E(slab) - E(NO), on the FeO2 terminated LaFeO3 (001) surface with and without oxygen vacancies (VO). The plane-wave pseudo-potential density functional theory method as implemented in the Quantum-ESPRESSO package was used throughout the calculations[1]. The Perdew-Burke-Ernzerhof-Generalized Gradient approximation (PBE-GGA) was employed for the exchange-correlation functional.
As a result, on a clean surface of the LaFeO3 slab, the system realizes G-type antiferromagnetic ordering and high-spin configurations. Also, the Eads is evaluated around -1 eV, resulting in a tendency of NO adsorption. In case of a surface slab with VO of 25 at% with respect to the surface O in 1st FeO2 layer, the value is evaluated to be -1.35 eV close to that without VO, forming a bond between nitrogen of adsorbed NO with Fe in the 1st layer with the VO. In case of a surface slab with VO of 50 at% in the 1st FeO2 layer as shown in the figure, the value is evaluated to be -2.17 eV, leading to the enhancement of adsorption energy. We find strong anti-parallel spin coupling between the adsorbed NO and the Fe. We also find that formation of donor states due to the surface VO enhances the adsorption energy of NO.