Modeling studies on the uptake of hydrogen molecules by graphene

Detailed ab initio molecular orbital calculations on the interactions of molecular hydrogen, H₂, with various poly-aromatic hydrocarbons (PAHs) as a model system for graphene were carried out to accurately describe the physisorption phenomenon. The binding energies corrected for the basis set superposition error, ΔE_bind(BSSE), were obtained using the optimized geometries at the MP2 level with a large basis set and were compared with the single point binding energies, denoted as ΔE_bind(BSSE-s), using large basis sets on the geometries optimized at the small basis sets, such as SVP and TZVP. The calculations showed that the ΔE_bind(BSSE-s) values were similar to those at the MP2 level with the large basis sets. The binding strength increased gradually with increasing size of the PAHs. The ΔE_bind(BSSE-s) for an infinite graphene sheet was estimated to be −1.70 kcal mol⁻¹ using the non-linear curve fitting method. The present work could be expected to provide more useful and reliable information on H₂ physisorption.