Screened Fe3 and Ru3 Single-Cluster Catalysts Anchored on MoS2 Supports for Selective Hydrogenation of CO2

Efficient CO2 hydrogenation into valuable products is a promising strategy to address environmental issues and achieve green development goals, yet developing highly active and selective catalysts still remains a major challenge. The single-cluster catalysts frequently exhibit unexpected catalytic performance for complex reactions in heterogeneous catalysis due to the synergistic interaction between the active atoms. In this work, we have proposed candidate catalysts with Fe3 and Ru3 clusters anchored at the S vacancies on the MoS2 substrate for highly selective CO2 hydrogenation, which is screened from a series of transition-metal clusters including Fe3, Co3, Ni3, Ru3, Rh3, and Pd3 by employing density functional theory calculations. The electron structure analysis reveals that the orbital interactions between metal hydride and CO2 dominate the adsorption modes of CO2 molecules on M3 clusters, wherein CO2 forms a symmetrical η1–C adsorption mode on the Fe3 cluster and an asymmetric η2–C,O adsorption mode on the Ru3 cluster, thereby leading to different CO2 hydrogenation pathways. Furthermore, the underlying reaction mechanisms for CO2 hydrogenation on Fe3/MoS2–v and Ru3/MoS2–v have been explored, and the M3 clusters are suggested to act as electron reservoirs throughout the whole hydrogenation reaction. Combining with microkinetic simulations, we have showed the highly selective reactivity toward methanol formation on Fe3/MoS2–v and ethanol formation on Ru3/MoS2–v. Our work provides in-depth atomic-scale insights into the mechanism of CO2 transformation in transition-metal single-cluster catalysis, which would provide ideas for the design and development of highly selective catalysts for CO2 hydrogenation.