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

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 O-2). 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 O-2 reacts with CO to form 0000 complex with smaller energy barrier (0.57 eV) than those of the formed CO3 complex (1.08 eV) and the dissociated O-2 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. (C) 2016 Elsevier Ltd. All rights reserved.