π–π interactions between benzene and graphene by means of large-scale DFT-D4 calculations

Abstract

The adsorption of aromatic molecules on graphene is essential for many applications. This study addresses the issues associated with predicting accurate binding energies between graphene and benzene using a series of increasingly larger nanographene (C24H12, C54H18, C96H24, C150H30, and C216H36). For this purpose, we consider several DFT methods developed for accurately predicting noncovalent interactions, namely, PBE0-D4, ωB97X-D4, PW6B95-D4, and MN15. The C150H30 and C216H36 nanographene predict binding energies converged to sub-kJ mol−1 with respect to the size of the nanographene. For the largest C216H36 nanographene, we obtain binding energies of −37.9 (MN15), −39.7 (ωB97X-D4), −40.7 (PW6B95-D4), and −49.1 (PBE0-D4) kJ mol−1. Averaging these values, we obtain ΔEe,bind = −41.8 ± 8.6 kJ mol−1, which translates to ΔH0,bind = −41.0 ± 8.6 kJ mol−1. This theoretical binding energy agrees with the experimental value of −48.2 ± 7.7 kJ/mol within overlapping uncertainties.