Dispersion corrected density functional study of CO oxidation on pristine/functionalized/doped graphene surfaces in aqueous phase

Abstract

The catalytic oxidation of CO by molecular oxygen (O2) over graphene, epoxy functionalized graphene and sulphur doped graphene surface is investigated theoretically by employing dispersion corrected Density Functional Theory. The adsorption of O2 and CO molecules over the pristine, functionalized and doped graphene surface has been compared. The channel for oxidation of CO to CO2 is elucidated in detail in the presence of aqueous solvent. Computations suggest that catalytic cycle of CO oxidation is initiated through the ER-mechanism, with the formation of a carbonate intermediate, the second pre-adsorbed CO reacts with the carbonate intermediate through LH-mechanism whereby, two CO2 molecules are released and adsorption surface becomes available for the subsequent reaction. The activation barrier for CO oxidation is considerably lowered in the case of oxidation over functionalized 12.45kcal/mol and doped 14.52kcal/mol graphene surface in comparison to the observed barrier of 23.98kcal/mol for the pristine graphene.