Photocatalytic Oxidation of Cyclohexane in a Biphasic System Using Rapidly Synthesized Polymeric Carbon Nitride Films

The oxidation of cyclohexane (CHA) to cyclohexanol and cyclohexanone (collectively known as KA oil) is a key C–H activation reaction and holds a central step in Nylon™ production. However, traditional processes suffer from low conversion and complex reaction conditions. Photocatalytic approaches under ambient conditions offer a sustainable alternative, though most rely on suspended powders with challenges in light management, catalyst recovery, and scalability. Here, we demonstrate the use of immobilized carbon nitride films for visible light-driven oxidation of CHA in a biphasic CHA–water system at a mild temperature. The system achieves high KA oil yields without stirring, enabling better light utilization and operational simplicity. Product selectivity proved to depend on the type of acid added: HCl favors cyclohexanone, while HBr enhances cyclohexanol formation. Mixtures of both acids allow fine-tuning of the product ratio. These findings highlight the potential of scalable CN-based photocatalyst panels for energy-efficient KA oil production under benign conditions. The highest product yield was achieved after 6 days in a biphasic CHA + 1 M HCl system, obtaining 155 µM cm−2 KA oil.