Single Atom Catalysts on Cr2NO2 MXene for CO Oxidation

Abstract

This work studies, by means of density functional theory, the adsorption of carbon monoxide (CO) molecules and their subsequent oxidation to carbon dioxide (CO2) on the MXene Cr2NO2 decorated with a single atom of transition metal (Sc, V, and Ti) by the Eley-Rideal mechanism. The dynamic stability of the MXene is evaluated through phonon calculations, and the thermal stability of the structure is determined by ab initio molecular dynamics. First, an oxygen (O2) molecule is adsorbed onto the metal atom. Sc and Ti provide a partial dissociation, while V exhibits a full decomposition into atomic O. For the first CO oxidation, all transition metals favor oxidizing CO, with Ti and V providing the larger and lower energy activation, respectively. However, in the second CO oxidation, the V site is poisoned since the CO2 molecule is unstable compared to adsorbed CO. In the Ti and Sc cases, CO2 formation is feasible, with Sc providing the lowest activation energies. Thus, the present study pinpoints Sc SACs on Cr2NO2 as an improved catalyst for CO oxidation reaction.