Tuning the content of S vacancies in MoS2 by Cu doping for enhancing catalytic hydrogenation of CO2 to methanol

Hydrogenation of CO2 to methanol is one of effective ways to promote "carbon neutrality". The activity of MoS2 as an efficient catalyst for the catalytic hydrogenation of CO2 to methanol is influenced by the content of in-plane S vacancies. Theoretically, the higher the density of in-plane S vacancies is, the better the performance of the catalyst is. In this work, a series of MoS2 nanosheets with different copper (Cu) dopant concentrations were prepared via hydrothermal method. It was found that the highest selectivity of MoS2-catalyzed CO2 hydrogenation to methanol along with the spatial-temporal yield was achieved at the Cu doping of 5%. Compared to the undoped MoS2 catalyst, the increase in methanol selectivity and spatial-temporal yield after doping was 13.37% and 2.27 times, respectively. This was due to the fact that Cu doping multiplied the number of S vacancies on MoS2, which altered the microstructure and chemical properties of the catalyst. However, a further increase in Cu dopant concentration reduced the S vacancy content on the MoS2 substrate, hindering the hydrogenation of the decomposed CO and thus decreasing the methanol yield. Therefore, a new technique to enhance MoS2-catalyzed CO2 hydrogenation to methanol was proposed.