Theoretical study on the reaction kinetics of CO oxidation by nitrogen-doped graphene catalysts with different ligand structures

Abstract

Harmful carbon monoxide (CO) gas from vehicle exhaust and fossil fuel combustion seriously affects the ecological environment and human health, although this issue can be effectively solved by low-temperature catalytic combustion. Herein, an Fe and N codoped double vacancy graphene catalyst (Fe-CxNy) for the low-temperature catalytic combustion of CO is proposed, and the mechanism of the CO catalytic combustion reaction over the catalyst is systematically investigated by using density function theory (DFT). Four oxidation mechanisms, including Eley–Rideal (ER1 and ER2), Langmuir-Hinshelwood (LH) and Termolecular Eley–Rideal (TER), were compared in terms of oxidation pathways and energy distribution. All the results indicate that Fe-CxNy catalysts have efficient catalytic activity. The Fe-CN3 catalyst with the predominant LH reaction mechanism showed the best performance for the catalytic combustion of CO with only 0.20 eV, which was comparable to that of noble metals. The rate constant calculations further demonstrate that Fe-CN3 exhibits excellent catalytic performance at low temperatures. This work not only provides a theoretical basis for the design and development of low-temperature catalytic combustion CO catalysts, but also provides data support for the kinetic model of CO combustion reaction.