Inverse CeO2/Cu Catalysts with Engineered Cu+-OV-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·gcat -1·s-1, which is 3.7 times higher than that of the conventional CeO2/Cu-10 (53.1 µmol·gcat -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+-OV-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.