Computational investigations of Cu-embedded MoS2 sheet for CO oxidation catalysis

Abstract

Elevated amount of CO levels in the atmosphere poses serious health and environmental hazards. Oxidation of CO using suitable catalysts is one of the methods to control it. By means of DFT calculations, single Cu atom doped in S vacancy of MoS2 nanosheet is studied for CO oxidation catalysis. Cu atom is strongly confined at the S-defective site of the MoS2 sheet, possessing high energy barrier for the diffusion to its neighboring sites. Adsorption energy, charge transfer and orbital hybridization of CO and O2 molecules adsorbed Cu-doped MoS2 sheet reveal that O2 is relatively more strongly adsorbed than CO. High adsorption energy of O2 (− 2.115 eV) and large charge transfer between O2 and Cu–MoS2 sheet (0.493e), compared to CO, make O2 adsorption more favorable, which extenuates CO poisoning and hence helps in the efficient CO oxidation process. The complete oxidation of CO takes place in two steps: $$ {\text{CO}} + {\text{O}}_{2} \to {\text{OOCO}} $$ with activation energy of 0.201 eV, succeeded by $$ {\text{OOCO}} + {\text{CO}} \to 2{\text{CO}}_{2} $$ without any energy barrier. Our results show that the basal plane of MoS2 sheet gets activated by embedding it with Cu metal, which can catalyze CO oxidation reaction effectively and without poisoning issues. The high activity, stability and low cost features can possibly encourage fabricating MoS2-based catalysts for CO oxidation reaction.