Adsorption properties of NH3, NO, and O2 molecules over the FeO (100) and oxygen-defected FeO (100) surfaces: a density functional theory study

Iron-based catalysts can be used as de-NOx catalysts due to their good adsorption performance to gas molecules. However, the adsorption behaviours of NH3, NO, and O2 molecules on ferrous oxide surface are unclear. In this paper, the adsorption properties of NH3, NO, and O2 molecules over FeO (100) surface and oxygen-defected FeO (100) surface were studied by a density functional theory calculation. The Fe-top of the FeO (100) surface is the most active site. NH3 and NO can be adsorbed on the Fe-top sites by N terminal. The adsorption of O2 on the Hollow site of the FeO (100) surface has a larger adsorption energy. When oxygen-defected presents on the FeO (100) surface, the adsorption performances of NH3 and NO on the Fe-top sites are slightly decreased. NO and O2 can be adsorbed on the O-defected site, in which the adsorption energy of O2 is larger. For the adsorption of double molecules, O2 + NH3 or O2 + NO adsorbed on the FeO (100) surface have synergistic effects, respectively, which enhance the adsorption performance. Moreover, the co-adsorption behaviours of O2 + NH3 and O2 + NO on the O-defected FeO (100) surface also occur.