Desorption Kinetics of Carbon Dioxide from a Graphene-Covered Pt(111) Surface.

The interaction of carbon dioxide (CO2) with a graphene-covered Pt(111) surface was investigated using temperature-programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS). The TPD spectra show monolayer and multilayer desorption peaks; however, the multilayer peak is not well-separated from the monolayer peak. The TPD spectra for submonolayer and multilayer coverages align on separate common leading edges. This alignment is a signature of zero-order desorption kinetics. The RAIRS spectra for submonolayer coverages have a relatively sharp peak at ∼2350 cm-1, which is assigned to the ν3 asymmetric stretch. The peak is observed at the onset of CO2 adsorption, and the area of the peak increases linearly with coverage. This suggests that CO2 does not lie flat on the surface but instead has a component of its bond axis perpendicular to the graphene surface.