Graphene and graphene nanomesh supported nickel clusters: electronic, magnetic, and hydrogen storage properties

Small-sized nanoparticles are widely used in applications such as catalysis, nanoelectronics, and hydrogen storage. However, the small size causes a common problem: agglomeration on the support template. One solution is to use templates that limit the mobility of the nanoparticles. Graphene nanomeshes (GNMs) are two dimensional porous structures with controllably passivated pores. In this work, we employ first principles calculations to investigate the potential for using GNMs as support templates for Ni clusters and, at the same time, study their magnetic and hydrogen storage properties. We consider two Ni clusters (Ni-6 and Ni-13) and two GNMs (O-terminated and N-terminated), comparing our results to those of isolated Ni clusters and those of Ni clusters on graphene. High stability of the Ni clusters is found on the N-GNM in contrast to the O-GNM. We quantify the hydrogen storage capacity by calculating the adsorption energy for multiple H-2 molecules. The values on Ni-x/N-GNM are significantly reduced as compared to the corresponding isolated Ni-x clusters, but a high hydrogen storage capacity is maintained. The fact that Ni-x/N-GNM hosts spin polarization is interesting for spintronic applications.