Role of the Support Effects on the Catalytic Activity of Gold Clusters: A Density Functional Theory Study

It is demonstrated that the support effects play a crucial role in the gold nanocatalysis. Two types of support are considered-the inert support of hexagonal boron nitride (h-BN) with the N and B vacancy defects and the active support of rutile TiO2(110). It is demonstrated that Au and Au-2 can be trapped effectively by the vacancy defects in h-BN. In that case, the strong adsorption on the surface defects is accompanied by the charge transfer to/from the adsorbate. The excess of the positive or negative charge on the supported gold clusters can considerably promote their catalytic activity. Therefore gold clusters supported on the defected h-BN surface can not be considered as pseudo-free clusters. We also demonstrate that the rutile TiO2(110) support energetically promotes H-2 dissociation on gold clusters. We show that the formation of the OH group near the supported gold cluster is an important condition for H-2 dissociation. We demonstrate that the active sites towards H-2 dissociation on the supported Au-n are located at corners and edges of the gold cluster in the vicinity of the low coordinated oxygen atoms on TiO2(110). Thus catalytic activity of a gold nanoparticle supported on the rutile TiO2(110) surface is proportional to the length of the perimeter interface between the nanoparticle and the support.