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

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.