Electronic and Structural Properties of C60 and Sc3N@C80 Supported on Graphene Nanoflakes

A theoretical study on the geometric and electronic structure of C60 and Sc3N@C80 absorbed on pristine graphene nanoflakes (GNFs) is presented. C60 is found to adsorb in two nearly degenerate configurations: with a pentagon facing the GNF, which is the most stable one, and with a hexagon facing the GNF in a face-to-face perfect alignment, rarely common in π–π interactions, 0.06 eV higher in energy. The calculated binding energy of 0.76 eV, which includes dispersion effects, is in good agreement with previous theoretical and experimental reports. On the contrary, Sc3N@C80 adsorption on the GNF resulted in a higher binding energy of 1.00 eV for nearly degenerate isomers that have a pentagon and a hexagon facing the SLG. This larger binding energy is explained in terms of a higher dispersion interaction between the larger metallofullerene and the GNF, and due to the fact that charge separation in Sc3N@C80, which results in a positively charged Sc3N inside a negatively charged C80, favors binding with the GNF...