Theoretical investigation of adsorption and dissociation of H_2 on (ZrO_2)n (n = l-6) clusters

摘要

The structure, vibration, and electronic structure of H_2 molecule adsorbed on (ZrO_2)_n (n = 1-6) clusters were investigated with density functional theory. We found that H2 is easily absorbed on the top Zr atoms of (ZrO_2)_n (n = 1-6) clusters. The Zr_5O_(10)H_2 cluster has the lowest binding energies in the Zr_n0_(2n)H_2 (n = 1-6) clusters. By analyzing vibrational frequency and Mulliken charge, the H-O and Zr-H bonds were found to be formed in different sized Zrn02nH2 clusters. The dissociation mechanism of H_2 shows that the charge transfers from ZrO_2)_n cluster to H_2 due to the important role of the orbital hybridization between the cluster and H_2 molecule. With increasing the number of H_2 molecule adsorbed on ZrO_2)_n clusters, the adsorption favors to the sites with low coordinate number, and these adsorption modes present a symmetrical tendency.