A Ni₃V₂O₈@g-CN nanocomposite-based p-n heterojunction: mechanistic insights into photocatalytic activation of the inert C(sp³)-H bond

Selective oxidation of C(sp³)-H bonds of aliphatic hydrocarbons to form value-added chemicals is still a challenging task being pursued. Herein, a p-n heterojunction based Ni₃V₂O₈@g-CN (NVO@g-CN) nanocomposite as a visible light active photocatalyst has been successfully reported for the activation and oxidization of an inert C(sp³)-H bond of cyclohexane under mild reaction conditions. Moreover, the p-n heterojunction formed enhances the charge separation at the interface leading to higher photocatalytic activity. Amid all composites, NVO-1@g-CN showed excellent performance towards the production of cyclohexanone with 93.4% selectivity. The plausible photooxidation mechanism was validated by EPR and UV-vis spectroscopy along with the scavenger experiments. Further mechanistic investigation using techniques like photocurrent density and photoluminescence experiments elucidate that the p-n heterojunction formed at the interface of the catalyst accelerates the charge separation by suppressing the recombination of photogenerated charge carriers. Thus, the p-n heterojunction based NVO@g-CN nanocomposite provides an efficient and sustainable approach for the selective photooxidation of cyclohexane.