Theoretical evaluation on single-atom Fe doped divacancy graphene for catalytic CO and NO oxidation by O2 molecules

Abstract

The geometric stability, electronic structure and surface activity of non-noble metal Fe doped divacancy graphene (555-777-graphene-Fe) sheet are investigated through density functional theory calculations. Firstly, the adsorption geometries and magnetic properties of different gas reactants on 555-777-graphene-Fe substrate are discussed in detail. It is found that the coadsorption of O2/NO or O2/CO molecules are more stable than that of the single NO or CO, indicating that the presence of O2 can promote the stability of reactants. Secondly, the possible catalytic oxidation reactions for NO or CO molecule are systematically analyzed through Eley-Rideal (ER), Langmuir-Hinshelwood (LH) and new termolecular Eley-Rideal (TER) mechanisms. Based on the calculated results, the interaction between 2 NO and 2CO molecules (2 NO + 2CO → 2CO2 + 2 N, 2 N → N2) through continuous reactions (< 0.3 eV) are an energetically more favorable than those of other reactions (LH, ER and TER). Furthermore, the preadsorbed O2 reacting with CO molecule through ER reactions are easily generated CO2 (< 0.3 eV) as compared with those of LH and TER reactions. This research provides a further theoretical study for NO and CO oxidation on graphene-based catalyst in ambient temperatures.