Advancing photocatalytic CH activation: VO2-Ag nanocomposites for efficient cyclohexane oxidation under mild conditions

The selective oxidation of inert C H bonds via sustainable photocatalytic methods represents a critical advancement in green chemistry. This research develops VO 2 -Ag nanocomposites for the selective photocatalytic oxidation of cyclohexane to KA oil (cyclohexanol/cyclohexanone) under mild conditions, addressing the inefficiency, high energy consumption, and over-oxidation of conventional methods. Oxygen-deficient VO 2 nanorods were synthesized solvothermally, followed by in situ photoreduction to deposit uniformly dispersed silver nanoparticles (Ag NPs) with the diameter of 6∼8 nm onto the VO₂ nanorod surface with the length of 500∼600 nm. The VO 2 -Ag synergy integrates three key features: (1) VO 2 oxygen vacancies modulating reactant adsorption, (2) Ag NP localized surface plasmon resonance (LSPR) enhancing visible-light absorption, and (3) a Schottky heterojunction promoting charge separation. The optimized VO 2 -Ag 40 composite achieved 9.17 % cyclohexane conversion and 95.04 % KA oil selectivity under visible light in 12 h, significantly outperforming pure VO 2 . Mechanistic studies identified h + , ·O 2 − , and ·OH as key active species. Enhanced activity stems from LSPR-broadened light absorption, Schottky-minimized charge recombination, and vacancy-optimized intermediate adsorption. This work highlights the potential of interfacial engineering and defect modulation in designing high-performance photocatalysts for sustainable hydrocarbon valorization, offering a scalable strategy for green chemical synthesis.