Density functional theory (DFT) was used to investigate the applicability of the graphene-supported Ni n nanoclusters as catalysts for the hydrogenation reaction. The adsorption and complete dissociation of the H2 on the Nin nanoclusters were investigated at the PBE-G/DNP level of theory. Accordingly, molecularly and dissociatively adsorbed hydrogens were seen on the Ni n (n = 2–3) and Ni n (n = 4–10) nanoclusters, respectively. The hydrogen adsorption on the Ni 6 and Ni 4 nanoclusters were more effective than other nanoclusters. Therefore, we investigated the hydrogen adsorption on the graphene-supported Ni 2 , Ni 4 and Ni 6 nanoclusters. The nanocluster adsorption energy on the graphene increased with the number of atoms in the nanocluster, whereas the adsorption energy per atom decreased. Hence, due to the stronger interactions of Ni-Ni than those of Ni-C, it seemed that the formation of nanoclusters on the graphene surface was favorable over the dispersion of the separate atoms. The results confirmed that the H 2 was dissociatively adsorbed on the graphene-supported Ni 4 and Ni 6 nanoclusters, which can make them good candidates as catalysts.
