Li adsorption on a graphene-fullerene nanobud system: density functional theory approach

Abstract

In this study, we investigated the mechanisms of Li adsorption on a graphene-C-60 nanobud system using density functional theory. Li adsorption on the hybrid system was enhanced compared to those using pure graphene and C-60. The Li adsorption energies ranged from -1.784 to -2.346 eV for the adsorption of a single Li atom, and from -1.905 to -2.229 eV for the adsorption of two Li atoms. Furthermore, adsorption energies were similar at most positions throughout the structure. The Li adsorption energy of an 18-Li adsorbed system was calculated to be -1.684 eV, which is significantly lower than Li-Li binding energy (-1.030 eV). These results suggest that Li atoms will be adsorbed preferentially (1) between C-60 and C-60, (2) between graphene and C-60, (3) on graphene, or (4) on C-60, rather than form Li clusters. As more Li atoms were adsorbed onto the graphene-C-60 nanobud system because of its improved Li adsorption capability, the metallic character of the system was enhanced, which was confirmed via analysis of band structure and electronic density of states.