Interface Engineering of Cu/CeO ₂ –Al ₂ O ₃ for Mixed-Oxide Interface-Driven Associative CO ₂ Activation in RWGS

Mixed-oxide catalysts show distinct catalytic behavior through crucial structural interactions among oxides and metals. While extensive research has focused on the individual roles of each oxide, the structural interactions in the mixed state and their role in catalytic mechanisms remain underexplored. To understand how mixed oxides alter catalytic behavior, we studied a suite of Cu-dispersed CeO2–Al2O3 catalysts in the reverse water gas shift (RWGS) reaction. Structural analyses revealed that beyond a certain ceria loading, further addition led to negligible nanostructural ceria evolution, marking the saturation of additional CeO2–Al2O3 interfacial structure formation and a corresponding plateau in catalytic performance. This finding indicates that catalytic activity is governed by the formation of CeO2–Al2O3 interfaces that stabilize active Cu species rather than by the total ceria loading. While ceria is well-known for its redox activity due to oxygen-vacancy properties, this study suggests that it also promotes the associative pathway through synergistic interactions with adjacent alumina domains, offering insights into reaction pathways in mixed-oxide catalysts. Overall, this study demonstrates that the CeO2–Al2O3 interface dictates both catalytic activity and mechanistic preference in the RWGS reaction, providing a design principle for developing interfacially engineered, mixed-oxide-supported catalysts for efficient CO2 conversion.