DFT study on H_2 and H adsorption and the electronic properties of single atom Cu modified Fe (111) surface

摘要

Density functional theory was used to study the adsorption of H-2 and H and electronic properties of single atom Cu modified Fe (1 1 1) including the Cu adsorption and substitution models. The adsorption ability of H-2 and H on Cu modified Fe (1 1 1) could be weakened by the weak adsorption sites provided by Cu atom, Cu occupying the strong adsorption sites of Fe (1 1 1), and weak adsorption of H-2 on Fe adjacent Cu, respectively. The analysis of electronic properties and crystal orbital Hamilton population of Fe-H bonds indicates that when Cu acts on Fe (1 1 1), the partial electrons of Fe can transfer to adjacent Cu, which weakens the bonding interaction between Fe and the adsorbed H-2 and H and then weakens adsorption of Fe (1 1 1) as following: (1) the more electrons Cu atom obtains, the weaker it adsorbs H-2 and H, (2) the more electrons Fe atom loses, the weaker it adsorbs H while there is an optimum charge point for H-2. Therefore, the adsorption, dissociation of H-2 and the catalytic activity of hydrogen-related reactions on Fe catalysts can be regulated by Cu modification, providing important information to further explore catalytic mechanism of syngas conversion reaction on Cu modified Fe catalysts.