MOF-Derived CuO@Co1-xCex-O Composite Oxides with Ce-Regulated Defect Chemistry and Interfacial Redox Synergy for Low-Temperature CO Oxidation under Tunnel-Fire Conditions

Carbon monoxide (CO) can rapidly accumulate in confined environments such as tunnel fires, posing an acute poisoning risk and demanding catalysts with low-temperature light-off and fast purification capability. Here, we construct a porous mixed-oxide framework from a Ce–Co metal–organic framework precursor and subsequently load 7 wt% CuO, yielding CuO@Co x Ce 1−x –O composite catalysts. Tricobalt tetraoxide (Co 3 O 4 ), Cerium dioxide (CeO 2 ) and Copper (II) oxide (CuO) are deliberately selected to couple reversible oxygen storage/defect regulation (Ce 4+ /Ce 3+ ), low-temperature redox cycling (Co 3+ /Co 2+ ), and interfacial charge-transfer sites for CO activation (CuO). Meanwhile, the MOF-derived strategy enables homogeneous component dispersion, abundant porosity, and intimate heterointerfaces, thereby maximizing interfacial synergy. Among the series, CuO@ Co 8 Ce 2 –O (Co:Ce = 8:2) exhibits the best performance, decreasing the temperature required for 90% CO conversion by 216 °C relative to the undoped counterpart and maintaining stable activity during prolonged operation. Correlating micromorphology, surface physicochemical properties, and redox/oxygen-mobility behavior reveals that moderate Ce incorporation increases defect-associated reactive oxygen species and accelerates oxygen transport, while strengthened Ce–Co electronic coupling further promotes interfacial synergy at the CuO–oxide junctions. Mechanistic evidence supports a Mars–van Krevelen pathway with dynamically regenerated interfacial oxygen vacancies, enabling rapid CO oxidation. This work provides a rational interface-engineering strategy for efficient CO purification in confined fire-related scenarios.