Divacancy-nitrogen/boron-codoped graphene as a metal-free catalyst for high-efficient CO oxidation

Metal-free catalysts have attracted wide attention due to their potentially catalytic applications. We performed density functional theory (DFT) calculations to investigate the different reaction mechanisms for CO catalytic oxidation on single-atom B incorporated into divacancy-nitrogen-doped graphene sheet (B-GN4). The calculated results show that the B atom can be strongly trapped at the active center of GN4 sheet and the formed B-GN4 configuration can be stable enough at high temperature. Based on the strong adsorption and significant activation of the reactants (CO and O2), the possible catalytic reactions of CO oxidation on the B-GN4 sheet are comparably studied through the Eley−Rideal (ER) and Langmuir-Hinshelwood (LH) mechanisms. In the sequential reactions, the dissociative adsorption of an O2 molecule as a starting step and following by the ER reactions (2O + 2CO → 2CO2) have much smaller energy barriers than the traditional ER and LH mechanisms. Besides, the dissociative reaction of CO molecule on the B-GN4 sheet, the formation process and surface activity of B-C codoped GN4 sheet (BC-GN4) are analyzed. This result indicates that the B-GN4 sheet as an anode material can promote the CO oxidation reaction, which provides a comprehensive understanding of graphene-based metal-free catalyst.