Size dependent catalytic effect of TiO2 clusters in water dissociation

Abstract: We performed systematic first principles calculations based on density functional theory to probe the energetics of dissociation of water molecules on small (TiO2) n (n =3, 4, 6, 8, and 10) clusters. We found that the (TiO2) n clusters have a strong ability to adsorb water molecules and the dissociative adsorption of water molecules on the surface of (TiO2) n clusters with a three step process is irreversible, size-dependent and energetically more favorable than the same on the surfaces of titanium oxide. Charged (TiO2) n cluster also have strong ability in H2O molecule splitting similar as neutral ones. The efficiency of water molecules dissociating on (TiO2) n cluster surface varies inversely with the cluster size due to the steric effect. Our results indicate a higher efficiency of small clusters of titanium oxide in dissociating water molecules than its low index surfaces of bulk terminated. [Copyright &y& Elsevier]