Inverse CeO₂/Cu Catalysts with Engineered Cu⁺-O_V-Ce³⁺ Interfacial Sites for Reverse Water Gas Shift Reaction

The reverse water-gas shift (RWGS) reaction can serve as a pivotal hub for converting CO₂ into value-added chemicals. However, conventional Cu/CeO₂ catalysts are constrained by a limited metal-oxide interfacial perimeter, suffering from both inadequate low-temperature activity and poor stability. Herein, a series of CeO₂/Cu-x catalysts (where x is the Ce/Cu molar ratio) were synthesized via an oxalic acid-assisted sol-gel coprecipitation method, and tested for RWGS at 400°C and atmospheric pressure. The optimal inverse CeO₂/Cu-0.1 achieves an intrinsic reaction rate of 197.0 µmol·g_cat ^-1·s^-1, which is 3.7 times higher than that of the conventional CeO₂/Cu-10 (53.1 µmol·g_cat ^-1·s^-1) and is much more stable. Structural analyses revealed that the CeO₂/Cu-0.1 is characterized by an inverse architecture of tiny CeO₂ crystallites (4.6 nm) on larger Cu particles (12.7 nm), which is distinct from conventional architecture of Cu clusters (3.3 nm) on larger CeO₂ particles (7.1 nm) for CeO₂/Cu-10. The inverse architecture significantly improves the density of Cu⁺-O_V-Ce³⁺ sites at the interfacial perimeter of CeO₂/Cu, which facilitates the synergistic activation of H₂ and CO₂ as well as subsequent reaction, leading to lower reaction orders and a much higher intrinsic rate. This work demonstrates the inverse oxide/metal architecture with engineered oxide-metal interfacial sites for enhancing RWGS.