Graphene nanoflakes and fullerenes doped with aluminum: features of Al-C interaction and adsorption characteristics of carbon shell

The aluminium-carbon interaction in two core-shell systems (Al22 nanoparticle coated with graphene nanoflake and Al@C60 metallofullerene) is investigated within the density functional theory. A set of non-equilibrium configurations of the coated Al22 nanoparticle is obtained from the ab initio molecular dynamics simulation. The Morse parameters describing the Al-C interaction are fitted based on density functional calculations performed at the B3LYP / 6-31G* level of theory. The Grimme’s D3 dispersion corrections are added to accurately account for the non-covalent interactions. It is shown that the concave carbon surface interacts much weaker with the nanoparticle and is located further away from it compared to the usually considered convex surfaces. Negligible charge transfer from aluminum core to carbon shell confirms that Al22 nanoparticle do not change the shell reactivity. In contrast, a single Al atom endohedrally doped C60 fullerene strongly interacts with the carbon cage and distorts the frontier molecular orbitals and reactivity of the compound. We also compare the hydrogen F..H-O bonds formed between the fluorinated C60F2 or Al@C60F2 cages and niacin drug molecule. We found that Al leads to drastic weakening of this hydrogen bond. We conclude that Al22 nanoparticle do not change reactivity of the carbon shell, whereas a single Al atom reduces reactivity of the outer fullerene.