First Principles Study of Different Atomic Exposure Terminals for Cu Adsorption on the Attapulgite (200) Surface

Abstract

The geometric structure, electronic structure, and charge transfer of transition metal Cu atoms adsorbed on different adsorption sites on three different termination surfaces (Mg/Al-O, Si1-O, and Si2-O) of Attapulgite (ATP) (200) slab were systematically studied by density functional theory (DFT) calculation method. The calculated results show that the adsorption energy of Cu adsorbed on the O atom Hcp site of the ATP (200) Mg/Al-O termination surface has the smallest adsorption energy and the most stable adsorption structure; the calculations and analysis of the density of states reveal that the strong p-d orbital hybridization occurs between Cu-O at the best adsorption site on the termination surface of ATP (200) Mg/Al-O, which makes the surface adsorption system very stable; through the calculation and analysis of Bader charge and deformation charge density, it is found that there is a significant charge transfer between the Cu atom and the adjacent O atom, and an open electron-poor region is formed above the Cu atom, which improves the ability of the ATP (200) surface to accept electrons. The calculated results are in good agreement with the experiments and effectively reveal the microscopic mechanism of the Cu-loaded modified ATP catalyst.