Nitrogen coordinated silicon-doped graphene as a potential alternative metal-free catalyst for CO oxidation

Abstract

Metal-free catalysts have attracted more attention due to their highly active in catalytic oxidation reactions. The outstanding stability and catalytic activity of a single-atom Si incorporated N4 centers in graphene (Si-GN4) are investigated using first-principles calculations. It is found that the Si-GN4 configuration can be stable at high temperature, the positively charged Si dopant as the active center can effectively regulate the adsorption of reactive gases (CO and O2). Besides, the possible reaction processes of CO oxidations on the Si-GN4 surface through the Eley−Rideal (ER) mechanism are comparably analyzed. In the CO oxidation reactions, the preadsorbed O2 reacts with CO to form OOCO complex with smaller energy barrier (0.57 eV) than those of the formed CO3 complex (1.08 eV) and the dissociated O2 reaction (0.74 eV), indicating that this reaction as starting stare is an energetically more favorable process. This result indicates that the much stable Si-GN4 sheet will be a highly efficient catalyst for CO oxidation, which is comparable to that of the noble metal catalyst.