Theoretical investigation of chemical reaction kinetics of CO catalytic combustion over NiNx-Gr

Abstract

Carbon monoxide (CO) produced by automobile exhaust emissions and fuel combustion is one of the domain pollutants severely causing experimental and human health problems, which catalytic combustion at low temperature is an effective way to remove. Here, a Ni and N co-doped double vacancy graphene catalyst (NiNx-Gr) was established for the combustion of CO at low temperature by regulating the number of N atoms. Based on the density function theory (DFT) method, the reaction mechanisms of CO catalytic combustion on different surface were developed, and the rate constants were also calculated by the means of transition state theory (TST). All NiNx-Gr catalysts exhibit excellent stability and catalytic performance, among which NiN3-Gr is the most outstanding. Molecular dynamics (MD) simulation results show that NiN3-Gr can still exist stably at the temperature of 1000 K. The calculation results of the potential energy surface show that CO is most advantageously oxidized by the TER mechanism on NiN3-Gr with a reaction energy barrier of only 1.71 eV. Furthermore, the results of the rate constants also indicate that NiN3-Gr is the most effective catalyst for CO combustion. All these results demonstrate that NiN3-Gr may serve as a high-performance material for catalytic CO combustion, which may offer some design insights for the experiments. This work not only proposes a catalyst for CO combustion, but also depicts a reasonable reaction mechanism in detail, which serves as a solid starting point for the further understanding of catalytic combustion kinetics of CO under low temperature.