Theoretical Calculation of Different Reaction Mechanisms for CO Oxidation on MnN3-Doped Graphene.

Abstract

In recent decades, great expectation has always been placed on catalysts that can convert toxic CO into CO2 under mild conditions. The catalytic mechanism of CO oxidation by Mn-coordinated N-doped graphene with a single vacancy (MnN3-SV) and a double vacancy (MnN3-DV) was studied by density functional theory (DFT) calculations. Molecular dynamics simulations showed that CO2 on MnN3-SV could not be desorbed from the substrate and MnN3-SV was not suitable for use as a CO oxidation catalyst. MnN3-DV was more suitable for CO oxidation (COOR) and from the electronic structure it was found that the Mn atom was the main active site, which was the reaction site for CO oxidation. At temperatures of 0 and 298.15 K, CO oxidation on MnN3-DV via the Langmuir–Hinshelwood (LH) mechanism was the best reaction pathway. The rate-determining step using MnN3-DV as the catalyst for CO oxidation through the LH mechanism was O2 + CO → OOCO, and the energy barrier was 0.861 eV at 298.15 K. MnN3-DV was suitable as a catalyst for CO oxidation in terms of both thermodynamics and kinetics. This study provides a comprehensive understanding of the various reaction mechanisms of CO oxidation on MnN3-DV, which is conducive to guiding the development and design of efficient catalysts for CO oxidation.