N, S dual defected CdIn2S4/C3N4 enhancing one-pot solvent-free photocatalytic synthesis of imine from alcohol oxidation and nitroaromatic reduction under visible light

Solvent-free photocatalytic synthesis of imine via the tandem coupling reaction between aldehyde from alcohol oxidation and amine from nitroaromatic reduction is a green route due to the photogenerated holes and electrons can be fully used for the oxidation and reduction reaction. In present study, N and S dual defected composite photocatalyst with Z-type heterojunction between CdIn₂S₄ and C₃N₄ was prepared. Under visible light irradiation, the coupling system of selective oxidation of benzyl alcohol to aromatic aldehydes and reduction of nitrobenzene to aniline was realized under solvent-free photocatalytic conditions. The yield of imine can reach 78.6 % with a selectivity of 98.0 % at room temperature for 20 h, giving the formation rate of imine of 786 μmol∙g⁻¹∙h⁻¹ that is higher than the currently reported solvent-free and even solvent-based photocatalytic performances of the entitled reaction. The reason for this excellent catalytic performance is revealed and the photocatalytic mechanism is proposed. Besides, the present photocatalyst shows good substrate expanding for benzyl alcohol derivatives and nitrobenzene derivatives. This work provides a strategy for one-pot direct photocatalytic synthesis of imine from alcohols and nitroaromatics.