Catalytic synthesis of non-carbon fuel NH3 from easily available N2 and H2O over FeO(100) surface: study of reaction mechanism using the density functional theory

Abstract

The competitive adsorption and reaction mechanism of the catalytic synthesis of NH₃ from N₂ and H₂O over the FeO surface was investigated in this work. The theoretical calculation results indicated that H₂O was more easily adsorbed on the FeO surface than N₂. The FeO(100) surface was more stable for the adsorption of N₂ and H₂O. The interaction between N₂ and the FeO(100) surface was attributed to N and O atoms, and the interaction between H₂O and the FeO(100) surface was attributed to O and Fe atoms, which were caused by van der Waals forces and the chemical bond effect, respectively. In the synthesis process, H₂O was first dissociated over the FeO(100) surface, and the N₂ dissociation process was the controlling step in NH₃ synthesis. The theoretical calculation results also indicated that the –OH group was not conducive to the formation of the N-H bond, and it changed the controlling step from the dissociation of N₂ to the formation of –NH₂. Furthermore, the existence of O atoms or –OH groups from H₂O on the FeO(100) surface was not conducive to the dissociation of H₂O.