Efficient porous carbon nitride/Ag3PO4 photocatalyst for selective oxidation of amines to imines: Z-scheme heterojunction and interfacial adsorption

The Ag3PO4-loaded porous carbon nitride (PCN)-based composite (PCN/Ag3PO4) was synthesized by a simple method as a photocatalyst for the efficient oxidation of benzylamine to N-benzylidenebenzylamine under simulated sunlight. The PCN in the composite had abundant amino groups, which can form stable complexes with benzylamine through hydrogen bonding, demonstrating by FTIR and 1H NMR titrations. DFT further confirmed that these complexes were more favorable to form at the PCN edge. Based on the experimental results, the catalyst was successfully modified by adding functional groups to promote the contact between the reaction substrate and the active center, thereby improving the catalytic activity. The transfer pathway of photo-excited charge separation in heterojunction photocatalyst and the possible mechanism for catalyzing the oxidative coupling reaction of benzylamine was proposed. This study explained the mechanism of amine-rich PCN promoting the oxidative coupling reaction of benzylamine, which provided an important idea for the design of efficient catalyst.