Engineering Metal-Vacancy Synergistic Centers in Mo@MoO₂ for Robust CO₂ Hydrogenation

In multiphase catalysis, metal and support interactions are essential for efficient catalysis in the reverse water-gas shift (RWGS). In particular, the synergistic interaction between active metals and OV facilitates efficient CO₂ adsorption and subsequent hydrogenation. In this work, a Mo@MoO₂ catalyst enriched with metallic molybdenum and oxygen vacancies (Mo-OVs) was constructed through a one-step hydrogen thermal treatment. This catalyst demonstrated exceptional catalytic activity in RWGS, achieving a CO₂ conversion rate of 50.2% when operated at 600 °C. The catalyst maintains its activity for 160 h without deactivation, demonstrating excellent reaction stability. The results indicate that the transition metal oxide MoO₃ readily reduces to MoO_3-x and MoO₂, which can further reduce to Mo and a large number of OVs. Both theoretical calculations and characterization results confirm that these Mo-OV active sites enhance catalytic activity. In conclusion, the approach of designing synergistic centers composed of metal species and vacancies offers important guidance for the development of highly active catalysts that benefit from cooperative dual-site interactions.