DFT study on Ag loaded 2H-MoS2 for understanding the mechanism of improved photocatalytic reduction of CO2

Abstract

Transition metal modified molybdenum disulfide to improve the performance of photocatalytic reduction of carbon dioxide has been receiving much attention. Herein, a novel high-efficiency photocatalytic composite Ag/2H-MoS₂ has been constructed and simulated using density functional theory (DFT) for unveiling the mechanism of improved photocatalytic reduction of CO₂ in our experimental research. Our calculations about the band structure and electronic and optical properties indicate that the loading of Ag atoms enhances the photocatalytic performance of 2H-MoS₂ nanosheets by transferring the photogenerated electrons from the valence band of 2H-MoS₂ to the loaded Ag atoms. Furthermore, 20 wt% Ag loaded 2H-MoS₂ is the most suitable for the thermodynamic requirement of reducing CO₂ to CH₄ among the catalysts with different Ag loadings, and the formation of *CHO in 20 wt% Ag/2H-MoS₂ is the potential-determining step, whose Gibbs free energy reduces from 2.830 eV of 2H-MoS₂ to 0.925 eV. Meanwhile the thermochemical results predict the best path for reducing CO₂ on such a photocatalyst as CO₂ → *COOH → *CO → *CHO → *CH₂O → *OCH₃ → *CH₃OH → CH₄. The photocatalytic performance of pristine 2H-MoS₂ in CO₂ reduction is therefore significantly improved by loading silver. This research provides a theoretical reference for transition metal modified 2H-MoS₂ nanosheets.