▎ 摘　　要

The adsorption of CO2 molecules on monolayer epitaxial graphene on a SiC(0001) surface at 30 K was investigated by temperature-programmed desorption and X-ray photoelectron spectroscopy. The desorption energy of CO, on graphene was :determined to be (30.1+25.1) +/- 1.5 kJ/mol at low coverages and approached the sublimation energy of dry ice (27-25 kJ/mol) with increasing the coverage. The adsorption of CO2 on graphene was thus categorized into physisorption, which was further supported by the binding energies of CO2 in core-level spectra. 'The adsoriptiOn states of CO2 on graphene Were theoretically examined by means of the van der WadIS density functional (vdW-DF) method that includes nonlocal correlation. The experimental desorption energy was successfully reproduced with high accuracy using vdW-DF calculations; the optB86b-vdW functional was found to be most appropriate to reproduCe the desorption energy in the present system.