Metal- and Nonmetal-Atom-Modified Graphene as Efficient Catalysts for CO Oxidation Reactions

Abstract

This study explores the metal Co- and nonmetal-atom-codoped graphene (CoNMx-graphene, x = 1–3 and NM = N, Si, P) as substrates for CO oxidation reactions. By density functional theory calculations, we show the formation mechanism of CoNM3-graphene configurations and their corresponding electronic structures and magnetic properties. On the CoNM3-graphene sheets, the adsorbed O2 is more stable than that of the CO molecule and serves as the reactive species. Besides, the coadsorption of CO/O2 (or 2CO) has larger adsorption energies than those of the isolated O2 and CO molecules, which would be used as an initial state for the CO oxidation reactions. Furthermore, the possible reaction mechanisms for CO oxidation on CoNM3-graphene are investigated in detail. It is found that the Eley–Rideal (ER) mechanism (CO + O2 → CO2 + Oads) on CoN3-graphene sheets has a smaller energy barrier than that of another initial state (CO + O2 → CO3), which is energetically more favorable than the Langmuir–Hinshelwood and new term...