Enhancing CO2 hydrogenation to methanol via synergistic effect of MoS2 interlayer spacing and sulfur vacancy

Abstract

Hydrogenation of carbon dioxide (CO2) to methanol is an important reaction to convert CO2 into valuable products and reduce carbon emission. MoS2 is an effective catalyst for CO2 hydrogenation, but the synergistic effects of interlayer spacing expansion and surface sulfur vacancies strengthening have not been studied systematically. Here, this work report hydrazine hydrate as an effective reducing agent for MoS2. The reducing agent can not only expand the interlayer spacing of MoS2, but also increase the concentration of sulfur vacancies through a simple treatment. More importantly, the synergistic effect between the interlayer spacing and sulfur vacancy of MoS2 significantly increases the methanol space-time yield (STY). At 220 °C, 4 MPa, and 8000 mL·gcat-1·h-1, the MoS2-N2H4-4 catalyst exhibits 76.8% methanol selectively, 5.52% CO2 conversion, a high methanol STY of up to 0.1214 g·gcat-1·h-1 and lasts for at least 200 h. The structural-performance relationship was further studied using physio-chemical characterizations and DFT. These results provide valuable insights into the development of highly efficient MoS2 catalysts for CO2 hydrogenation.