Visible light-driven graphitic carbon nitride (g-C₃N₄) photocatalyzed ketalization reaction in methanol with methylviologen as efficient electron mediator

Ketalization reaction, which is otherwise a typical acid catalyzed process, is herein firstly realized by a novel visible light driven photocatalytic reaction system with methylviologen (MV²⁺) as an efficient electron mediator and graphitic carbon nitride (g-C₃N₄) as the visible light sensitizer. The photons utilization efficiency of g-C₃N₄was maximized by simultaneous removal of the conduction band electrons and valence band holes by MV²⁺and methanol, respectively. The turn over number of MV²⁺reaches the remarkable high value of 31201/hour, with 72.7 mmol of cyclohexanone dimethyl ketal production in 1 h. The design strategy presented in this work could inspire the development of new and highly efficient photocatalytic reaction systems for broader purposes than usually expected.