Synergistic Effect of Copper and Indium Species for Highly Selective CO2 Hydrogenation to Methanol

CO₂ hydrogenation to methanol over Cu-based catalysts faces challenges such as low methanol selectivity and poor stability. Here, we report a series of CuIn bimetallic catalysts with different Cu/In ratios prepared by the coprecipitation method. Among them, the methanol selectivity of Cu₂₅In₇₅ reaches as high as 92.5% at 200 °C and 64.5% at 260 °C, which is 1.3 times and 1.9 times higher than that of the commercial catalyst at 200 and 260 °C, respectively. Moreover, Cu₂₅In₇₅ exhibits high stability for 200 h time-on-stream at 260 °C. The high selectivity originates from a strong interaction between Cu species and In₂O_3–x with oxygen vacancies. On the interface between Cu and In₂O_3–x, dispersed Cu is the main contributor to the activation and dissociation of H₂, while the oxygen vacancies in In₂O₃ adsorb and activate CO₂. During the reaction, the abundance of hydrogen facilitates the reduction of the In₂O₃ surface, promoting the generation of surface oxygen vacancies and providing the necessary hydrogen for the hydrogenation reaction. Our research unveils a promising synergistic strategy for the rational design and application of Cu-based catalysts in CO₂ hydrogenation, offering avenues for further exploration and advancement in this field.