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

The competitive adsorption and reaction mechanism of the catalytic synthesis of NH3 from N-2 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 N-2. The FeO(100) surface was more stable for the adsorption of N-2 and H2O. The interaction between N-2 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 N-2 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 N-2 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.