Interfacial hydrogen bond effect between CeO2 and g-C3N4 boosts conversion to adipic acid from aerobic oxidation of cyclohexane

The selective oxidation reaction of cyclohexane is one of the typical activated sp3 C-H reactions, and its product adipic acid (AA) is the indispensable raw material used to produce nylon. However, subjecting to the inertness of C-H bond and the great reactivity of AA, the targeted transformation of cyclohexane remains a challenge. Here, the interfacial hydrogen bond (IHD) was developed by anchoring CeO2 on graphite carbon nitride (g-C3N4) surface, which could boost targeted acquisition adipic acid from aerobic oxidation of cyclohexane. The results indicated that the IHD effect can be flexibly regulated by changing the ratio of Ce3+/Ce4+, further optimizing the properties of surface OH species and Lewis acid sites. Under the synergistic effect of Ce3+/Ce4+ and Lewis acid sites on reaction interface, the glorious performance (32.2% conversion of cyclohexane with 66.4% selectivity) was obtained over the as-prepared CeO2/g-C3N4 IHD system. In addition, the interfacial adsorption properties of cyclohexane were explored by the virtue of in situ infrared spectroscopy, revealing the IHD effect could tune the adsorption behavior of cyclohexanone and further improve the selectivity of AA. This work disclosed that engineering the interface hydrogen bond effect between CeO2 and g-C3N4 provided feasible strategies to obtain excellent catalyst for cyclohexane oxidation.