CeO2–δ‐Modified CuFe2O4 with Enhanced Oxygen Transfer as Efficient Catalysts for Selective Oxidation of Fluorene under Mild Conditions.

The design of efficient catalysts for the selective oxidation of sp3 C–H bond with air at low temperature is of great importance to the scientific and industrial community. In this work, we design a CeO2–δ modified CuFe2O4 catalyst by a post‐modification method for the selective oxidation of fluorene under an air atmosphere and N‐hydroxyphthalimide (NHPI) at 60 °C. HRTEM results indicate that CeO2–δ nanoclusters sized around 5 nm are successfully modified on the surface of CuFe2O4. XPS and H2‐TPR results show that CeO2–δ modification would favor oxygen transfer at lower temperature due to the synergetic effect between CuFe2O4 and CeO2–δ with rich Ce3+/Ce4+ couples. The results demonstrate that CuFe2O4@CeO2–δ‐0.05 with 4.20 wt.‐% Ce present the best catalytic performance with 94 % conversion of fluorene and excellent reusability at least five times. It is anticipated that the modification of CeO2–δ nanoclusters on the surface leads to increased oxygen activation and transfer to CuFe2O4, which favors the activation of NHPI to phthalimide‐N‐oxyl (PINO) radicals and exhibits an improved catalytic performance. Our results provide some guidance on the design of efficient catalysts by the surface modification strategy. CeO2–δ modification with 4.20 wt.‐% Ce on the surface of CuFe2O4 nanoparticles favors oxygen transfer at lower temperature and leads to better catalytic activity than that of pure CuFe2O4 for the aerobic selective oxidation of fluorene due to the synergetic effect between CuFe2O4 and CeO2–δ with Ce3+/Ce4+. [ABSTRACT FROM AUTHOR]