Synergistic effect of dual active sites in Cu–Ni bimetallic catalysts for high-efficiency CO2 hydrogenation with 98.5% methanol selectivity

Take into consideration the backdrop of global energy crisis and rising carbon dioxide concentration in the atmosphere, to research and develop efficient catalysts for converting CO 2 into sustainable energy is crucial. Based on this background, this study employed the complexation combustion method to prepare CuNi nanoclusters (NCs) with varying atomic ratios and applied in catalytic hydrogenation of CO 2 to CO or methanol. Through systematic characterization techniques such as XRD, SEM, BET, in-situ XPS, EPR, and chemisorption, the crystal phase structure, morphological features, physico-chemical properties, and catalytic performance of the as-obtained catalysts were thoroughly analyzed. The results of activity measurements demonstrate that the electronic synergy between CuNi bimetals exerts a positive catalytic effect on CO 2 hydrogenation to methanol. Notably, the Cu 1 Ni 1 catalyst achieved the striking methanol selectivity (98.5%) while maintaining a higher conversion of CO 2 (11.4%). Specifically, thanks to the employment of acetic acid complexation together with the isolation and stabilization effects of Ni species, a considerable amount of metastable Cu + is detected in the obtained catalyst as evidenced by XRD and in-situ XPS, which synergistically interacts with Cu 0 and facilitates the redox cycling of Cu active sites for CO 2 hydrogenation. Besides, the CO 2 -TPD and EPR show that a higher concentration of oxygen defects and the resulting large number of basic sites with moderate strength greatly facilitate the adsorption of CO 2 and hydrogenation to methanol; however, the excessively sites with strong basicity which present on the surface of Cu 0 Ni 1 generate the strong adsorption of CO 2 molecules, making the reaction route turned to the reverse water gas shift which is conducive to the hydrogenation of CO 2 to CO. Thus, the bond strength between CO 2 and basic site could alternate the mechanism of catalytic reaction on supported copper based catalysts.