Density functional study on the CO oxidation reaction mechanism on MnN 2 -doped graphene.

The CO oxidation mechanisms over three different MnN 2 -doped graphene (MnN 2 C 2 : MnN 2 C 2 -hex, MnN 2 C 2 -opp, MnN 2 C 2 -pen) structures were investigated through first-principles calculations. The vacancy in graphene can strongly stabilize Mn atoms and make them positively charged, which promotes O 2 activation and weakens CO adsorption. Hence, CO oxidation activity is enhanced and the catalyst is prevented from being poisoned. CO oxidation reaction (COOR) on MnN 2 C 2 along the Eley-Rideal (ER) mechanism and the Langmuir-Hinshelwood (LH) mechanism will leave one O atom on the Mn atom, which is difficult to react with isolated CO. COOR on MnN 2 C 2 -opp along the ER mechanism and termolecular Eley-Rideal (TER) mechanism need overcome low energy barriers in the rate limiting step (RLS), which are 0.544 and 0.342 eV, respectively. The oxidation of CO along TER mechanism on MnN 2 C 2 -opp is the best reaction pathway with smallest energy barrier. Therefore, the MnN 2 C 2 -opp is an efficient catalysis and this study has a guiding role in designing effective catalyst for CO oxidation.