Effect of α-SiO2 substrate on the CO adsorption onto graphene using density functional theory calculations

Abstract

The adsorption mechanism of CO gas molecule onto the surface of free-standing graphene and graphene on the α-SiO₂ substrate is studied using the density functional theory. CO molecule is found to be physically adsorbed on the graphene surface. The adsorption properties of CO gas on free-standing graphene and graphene/α-SiO2, such as adsorption energy, adsorption distance, and response length, are calculated in detail. α-SiO₂ has been found as a good substrate to enhance the adsorption energy of CO onto graphene. The electronic band structures and density of states (DOS) analysis results show that the interaction between α-SiO₂ and graphene breaks the symmetry of graphene and a tunnelling bandgap occurs at the Dirac point. α-SiO₂ substrate modifies the electronic band structures of free-standing graphene and opens a narrow bandgap of 51 meV. The calculated charge transfer data suggest that the presence of α-SiO₂ enhances the charge donation of CO molecule to the graphene surface.