Implanting Redox Dual Sites on Crystalline Carbon Nitride for High‐Efficiency Photocatalytic Selective Oxidative Coupling of Benzylamine into N‐benzylidenebenzylamine

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ABSTRACT Efficient photocatalysis over polymeric carbon nitride (PCN) for value‐added chemical synthesis is challenged by rapid charge carrier recombination and sluggish surface redox reaction kinetics. Herein, crystalline carbon nitride (CCN) introduced with Co single atoms and cyano groups (Co‐CCN) was successfully synthesized through a molten‐salt method for photocatalytic selective oxidative coupling of benzylamine (BA) into N‐benzylidenebenzylamine (NBBA). In comparison to PCN and CCN, the obtained Co‐CCN exhibits much higher photocatalytic performance, with both BA conversion and NBBA selectivity reaching 99%. Moreover, the NBBA yield, reaching 24.75 mmol g −1 h −1 , encouragingly outperforms almost all the reported PCN‐based photocatalysts. Spectral characterizations and theoretical calculations reveal that the electron‐deficient Co‐N 4 sites act as oxidation sites, promoting hole accumulation and facilitating the adsorption and activation of BA, while the strongly electron‐withdrawing cyano (‐C≡N) groups act as efficient electron‐extraction sites, enhancing charge separation and promoting O 2 absorption and activation, which synergistically contributes to the excellent photocatalytic activity. This study demonstrates a guidable strategy to the rational and cooperative modulation of molecular and electronic structures for efficient photocatalysis toward selective oxidative coupling of BA into NBBA, and also deepens the understanding of active sites engineering in photocatalytic organic transformation.

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