Defect-engineered Cu O/CeO2 catalysts: Enhanced low-temperature CO preferential oxidation through dual-promotion of CO adsorption and O2 activation

• A mesoporous CeO 2 support with abundant oxygen vacancies was synthesized via pyrolysis of Ce-BDC MOF precursor. • The high-density mesoporous structure facilitates the dispersion of Cu x O species and generates more active Cu⁺ sites. • The coexistence of abundant oxygen vacancies and Cu⁺ sites synergistically enhance CO adsorption and O 2 activation. • The optimized 15Cu x O/CeO 2 –O exhibits remarkable catalytic performance at low temperatures. The preferential oxidation of CO (CO-PROX) represents a critical strategy for trace CO elimination in hydrogen purification, where CO adsorption and O 2 activation are crucial for enhancing catalytic performance. Herein, we report a defect-engineered strategy mediated by MOF to promote CO adsorption and O 2 activation. By pyrolyzing Ce-BDC MOF , we synthesized CeO 2 –O support with a high–density mesoporous structure and high surface area, facilitating the well-dispersion of Cu ₓ O species and forming abundant interfacial Cu + active sites. The well-dispersed Cu x O species enhance their interaction with CeO 2 –O, resulting in weakened Ce–O bonds and promoting both lattice oxygen activation and oxygen vacancy (Vo) formation for enhanced O 2 activation. The optimized 15Cu x O/CeO 2 –O catalyst demonstrates exceptional catalytic efficiency, achieving complete CO conversion at a comparatively low temperature (T 100 % = 115 °C), coupled with broad temperature window applicability and outstanding stability over multiple cycles. This work establishes a MOF-guided paradigm for engineering multifunctional catalytic sites, offering a generalizable approach to design high-performance oxide catalysts for hydrogen purification and beyond.