▎ 摘　　要

The stable configuration, electronic structure, magnetic property, and catalytic activity of single-atom Co catalyst on graphene substrates are investigated using the first-principles calculations. In contrast to the pristine graphene, a vacancy defect in graphene strongly stabilizes the Co atom and makes it more positively charged, which helps to facilitate the adsorption of O-2 molecule and alleviate the CO poisoning of catalyst, since the larger adsorption energy of O-2 gains more transferred electrons from Co-graphene substrates as compared with that of the CO molecule. Besides, the anchored Co atom and adsorbed gas molecules can regulate the electronic structure and magnetic property of graphene substrates. Moreover, the sequential processes of CO oxidation on the Co-embedded graphene system have lower energy barrier (0.42 eV) by the Langmuir-Hinshelwood (LH) reaction (CO + O-2 -> OOCO) and is followed by the Eley-Rideal (ER) reaction with smaller energy barrier of 0.19 eV (CO + O-ads -> CO2). The results provide valuable guidance on selecting the catalyst of low cost and high activity to fabricate graphene-based materials, and the atomic-scale catalyst supported on graphene would be potential for gas sensors, spintronics and catalytic electrode in fuel cells. (C) 2015 Elsevier B.V. All rights reserved.