Mechanistic insights into Ce-modulated reaction pathways for CO2 hydrogenation to methanol over Cu/ZnO catalysts

Ce-modified CuZn-based catalysts show promising performance in CO 2 hydrogenation to methanol. However, probing the nature of their active surface and elucidating the role of Ce in regulating reaction pathways at the molecular level remain challenging. In this study, a series of CuZnCe catalysts were prepared with varying CeO 2 contents. Kinetic tests reveal that CuZnCe catalysts exhibit significantly higher activity and methanol selectivity compared to the unmodified CuZn catalyst. In-situ AP-XPS analysis demonstrates that Ce species preferentially migrate toward the catalyst surface and exist predominantly in the form of Ce 3 + during CO 2 hydrogenation to methanol. In-situ DRIFTS confirms that the CuZn catalyst facilitates the direct hydrogenation of CO 2 to methanol via a formate intermediate. In contrast, the introduction of Ce shifts the reaction mechanism toward the reverse water-gas shift reaction followed by CO-hydrogenation (RWGS + CO-hydro), as Ce 3+ sites display a high propensity to stabilize carboxylate (CO 2 δ- ) intermediates derived from CO 2 . Meanwhile, the Cu-ZnO x interface remains essential for H 2 dissociation and supplying hydrogen species. The enhanced catalytic performance of the CuZnCe catalysts is primarily attributed to the synergistic effects between the Cu-ZnO x and Cu-CeO x interfaces. These findings highlight the pivotal role of metal-oxide interfaces in controlling reaction pathways and methanol selectivity during CO 2 hydrogenation to methanol, providing valuable insights for the rational design of high-performance catalysts.