Atomically Dispersed Co/C3n4 for Boosting Aerobic Cyclohexane Oxidation

In the present work, the atomically dispersed Co on C3N4 was synthesized by coupling the one-pot strategy with the electrostatic adsorption method and applied into the aerobic oxidation of cyclohexane. The characterization results of the resulting Co/C3N4-w revealed that the single-atom Co with the positive charge existed in the form of Co-N pairs in the sixfold cavities of C3N4 along with the electron transfer from Co atoms to C3N4. The catalytic activity of Co/C3N4-w presented the positive correlation with the loading of the single-atom Co, and the superior catalytic performance with 34.3% conversion and 95.2% overall selectivity was obtained over Co/C3N4-0.02. Experiments combined with DFT calculations demonstrated that the single-atom Co with the unsaturated coordination favored the dissociation activation of O2 and decomposition of the intermediate cyclohexylhydroperoxide, and the adsorption of cyclohexane on the C3N4 surface was enhanced due to the increased electron density, boosting the cyclohexane oxidation. Distinctively, Co/C3N4-0.02 exhibiting the high stability for the cyclohexane oxidation originated from the robust Co-N structures and hydrophobic nature of the C3N4 surface.