Modulating Cu species in copper–ceria catalyst for boosting CO preferential oxidation: Elucidating the role of ceria crystal plane

Copper–ceria has been regarded as an active catalyst for CO preferential oxidation (CO-PROX). However, modulation of Cu species by regulating the ceria crystal plane has remained largely underdeveloped. Herein, CuO/CeO2-X catalysts (X stands for treating temperature) were synthesized by the freeze-drying impregnation method using CeO2-X nanorods with variational termination planes as supports and employed to boost CO-PROX. The results from various characterization techniques reveal that the mass transfer between CuOx clusters and CeO2-X weakened, and the sintering of CuOx enhanced as the stability of CeO2-X exposed planes increased. It is manifested that the content and the effective diameter of CuOx clusters increase, and the cerium doping in CuOx clusters decreases. The CuO/CeO2-400 catalyst prepared from CeO2-400 with suitable crystal plane stability induces the most significant amount of Cu+–CO during the CO-PROX reaction, displaying optimal reactivity. This work expounds on the relationship between the initially exposed crystal plane of CeO2 and the structure of Cu species after loading CuO, which is of great significance for designing efficient catalysts for CO-PROX.