Oxidation of CO by N2O over Al- and Ti-doped graphene: a comparative study

In this work, we employ density functional theory calculations to investigate the CO oxidation mechanisms by N2O molecules over Al- or Ti-doped graphene (Al-/Ti-graphene). The reaction barriers and thermodynamic parameters are calculated using the M06-2X density functional with the 6-31G* basis set. The possible reaction pathway proposed for the oxidation of CO with N2O molecules is as follows: N2O -> N-2 + O-ads and CO + O-ads -> CO2. Unlike Al-graphene, upon adsorption of the N2O molecules over Ti-graphene, they are quickly dissociated into N-2 and Oads species via a barrier-less reaction. Then, the activated Oads reacts with CO molecules to form CO2 molecules. The calculated activation energies of the reaction CO + O-ads -> CO2 on Al- and Ti-graphene are calculated to be 0.06 and 0.16 eV, which are lower than those on traditional noble metal catalysts. Our results indicate that both Al- and Ti-graphene can be used as a potential catalyst for low-temperature CO oxidation by N2O molecules.