Continuous Flow Photocatalysis Boosting C─N Coupling for Sustainable High‐Efficiency Formamide Synthesis
Junchi Xu, G.H. Zhai, Gang Wang, Siyuan Yang, Zhenzhong Liu, Zilong Li, Jiawei Li, Chao Yang, Chengyuan Liu, Yang Pan, Haifeng Lv, Xiaojun Wu, Zhiyong Tang, Chao Gao, Yujie Xiong
Abstract
Abstract The construction of C─N bonds from simple precursors under ambient conditions is a fundamental challenge in green chemistry, especially when it comes to avoiding energy‐intensive protocols. Here, we present a continuous flow photocatalytic platform that enables the efficient coupling of C─N bonds between methanol and ammonia at ambient temperature and pressure. By synergistically engineering a Pd clusters‐decorated TiO 2 photocatalyst (1Pd/TiO 2 ) and a mass transfer‐enhanced gas–liquid–solid Taylor flow reactor, the system achieves a remarkable formamide productivity of 256.80 µmol h −1 (6.83‐fold enhancement compared to batch reactors) with less than 10% decay in production rate over 50 h of continuous operation, which is remarkably superior to state‐of‐the‐art photocatalytic systems for the synthesis of C─N compounds from C1 small molecules. Distinguishing from the conventional simultaneous bimolecular one‐electron oxidation pathway, a mechanistic study has shown that the precisely tailored Pd clusters on TiO 2 induce charge polarization to drive methanol dehydrogenation toward critical *CH 2 O intermediates, enabling direct nucleophilic NH 3 attack for C─N bond formation, thereby circumventing thermodynamic/kinetic barriers inherent to asynchronous radical generation in prior systems. This work establishes a paradigm for the sustainable, efficient synthesis of formamide via photocatalytic C─N coupling by bridging nanoscale photocatalyst engineering with macroscopic reactor design.