Ab initio molecular dynamics study of dissociative adsorption of H2 on defective graphene-supported Cu19 cluster

Abstract

The dissociative adsorption of H2 on Cu19 and defective graphene-supported Cu19 clusters (Cu19G) are investigated using ab initio molecular dynamics. The molecular-level trajectories show that, on Cu19, the preferred adsorption site is the bridge-hollow site, where the two H atoms are adsorbed at the bridge and hollow sites beside a Cu atom, with an adsorption energy of −0.74 eV. In contrast, on the defective graphene-supported Cu19 cluster, the favorite adsorption site is located where the two H atoms are adsorbed at hollow-hollow sites with an adsorption energy of −1.27 eV. In general, the average adsorption energy on the defective graphene-supported Cu19 cluster is −1.07 eV, which is about 84% larger than that of −0.58 eV on the Cu19 cluster. This indicates that the adsorption capacity is greatly enhanced for the dissociative adsorption of H2 on the defective graphene-supported Cu19 cluster. The d-band center shifts to the Fermi level, illustrating the enhanced adsorption capacity on the defective graphene-supported Cu19 cluster. The integrated crystal orbital Hamilton population analysis reveals that stronger bond interactions between hydrogen atoms with their bonded Cu atoms lead to much larger adsorption energies on the defective graphene-supported Cu19 cluster compared to the Cu19 cluster.