Evolution of Small Ti Clusters and the Dissociative Chemisorption of H₂ on Ti

Abstract

The sequential growth of small titanium clusters with up to 15 atoms and the dissociative chemisorption of H2 on the minimum energy clusters have been studied within density functional theory under the generalized gradient approximation. It has been found that the low-energy clusters grow three dimensionally from Ti4 and follow a pentagonal growth pattern. The clusters Ti7 and Ti13 show a higher stability than other clusters with a configuration of pentagonal bipyramid and icosahedron structures, respectively. The second difference of binding energy plot indicates that these two clusters are highly stable; this agrees with the experimental collision-induced dissociation studies and previous theoretical calculations. For the first time, a systematic study of chemical reactivity of small Tin clusters, with n = 2−15, toward dissociative chemisorption of H2 is performed. It is found that the chemisorption occurs preferentially at the two adjacent edges of any Ti atom. The chemisorption energy as a function of the cluster size shows considerable structural changes in the Tin clusters due to H2 dissociation and adsorption, and the chemisorption energy of Ti13 cluster is found to be the highest.