Theoretical investigation of adsorption and dissociation of H2 on (ZrO2)n (n=1–6) clusters

The structure, vibration, and electronic structure of H2 molecule adsorbed on (ZrO2)n (n = 1–6) clusters were investigated with density functional theory. We found that H2 is easily absorbed on the top Zr atoms of (ZrO2)n (n = 1–6) clusters. The Zr5O10H2 cluster has the lowest binding energies in the ZrnO2nH2 (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 ZrnO2nH2 clusters. The dissociation mechanism of H2 shows that the charge transfers from (ZrO2)n cluster to H2 due to the important role of the orbital hybridization between the cluster and H2 molecule. With increasing the number of H2 molecule adsorbed on (ZrO2)n clusters, the adsorption favors to the sites with low coordinate number, and these adsorption modes present a symmetrical tendency.

► H2 is easily absorbed on the top Zr atoms of (ZrO2)n (n = 1–6) clusters. ► The dissociation mechanism of H2 shows charge transfers from (ZrO2)n cluster to H2. ► With increasing number of H2, the adsorption favors to low coordinate sites. ► These adsorption modes present a symmetrical tendency.