A density functional theory study of gold clusters supported on layered double hydroxides

The geometrical structure and electronic properties of a series of Au (N) (N = 1-8) clusters supported on a Mg2+, Al3+-containing layered double hydroxides (MgAl-LDH) are investigated using density functional theory. The Au clusters are supported on two typical crystal faces of the LDH platelet, the basal {0001} and the lateral crystal face, respectively, corresponding to the top and edge site of monolayer MgAl-LDH lamella for the sake of simplicity. It is revealed that an increase in the charge transfer from the LDH lamella to the Au (N) clusters at the edge site rather than clusters on the top surface, demonstrating a preferential adsorption for Au (N) clusters at the edge of LDH lamella. Moreover, the calculated adsorption energy of the Au (N) clusters on the LDH lamella increases with the cluster size, irrespective of the adsorption site. The investigation on the interaction between O-2 and Au (N) clusters on the LDH lamella is further carried out for understanding the catalytic oxidation properties of the LDH-supported Au catalyst. The formation of reactive O-2 (-) species, a necessary prerequisite in catalytic oxidation of CO, by O-2 bridging two Au atoms of Au (N) clusters indicates that the LDH-supported Au catalyst has the required characteristics of a chemically active gold catalyst in CO oxidation.