▎ 摘　　要

Activation of the Ti-4 cluster on defective graphene for water adsorption and dissociation was investigated via density functional theory. Both the vacancy and the Ti cluster can promote the water dissociation reaction. The vacancy can efficiently enhance the adsorption of Ti atoms to stabilize the cluster. However, compared to the role of the vacancy, the cluster plays a more important role in activating water dissociation. A single water molecule and a second one can almost freely dissociate with (or without) a low barrier on the Ti-4 cluster, the barriers are substantially lower than that on a single Ti atom. The Ti-4 cluster decorated graphene is a promising candidate for activation of the dissociation of water molecules.