Photocatalytic Formamide Synthesis via Coupling of Electrophilic and Nucleophilic Radicals over Atomically Dispersed Bi Sites
Weiping Yang, Lei Xiao, Haoran Wu, Xin Li, Qin Ren, Jieyuan Li, Ying Zhou, Fan Dong
Abstract
Abstract Formamide (HCONH 2 ) plays a pivotal role in the manufacture of a diverse array of chemicals, fertilizers, and pharmaceuticals. Photocatalysis holds great promise for green fabrication of carbon‐nitrogen (C−N) compounds owing to its environmental friendliness and mild redox capability. However, the selective formation of the C−N bond presents a significant challenge in the photocatalytic synthesis of C−N compounds. This work developed a photocatalytic radical coupling method for the formamide synthesis from co‐oxidation of ammonia (NH 3 ) and methanol (CH 3 OH). An exceptional formamide yield rate of 5.47±0.03 mmol ⋅ g cat −1 ⋅ h −1 (911.87±5 mmol ⋅ g Bi −1 ⋅ h −1 ) was achieved over atomically dispersed Bi sites (Bi SAs ) on TiO 2 . An accumulation of 45.68 mmol ⋅ g cat −1 (2.0 g ⋅ g cat −1 ) of formamide was achieved after long‐term illumination, representing the highest level of photocatalytic C−N compounds synthesis. The critical C−N coupling for formamide formation originated from the “σ–σ” interaction between electrophilic ⋅CH 2 OH with nucleophilic ⋅NH 2 radical. The Bi SAs sites facilitated the electron transfer between reactants and photocatalysts and enhanced the nucleophilic attack of ⋅NH 2 radical on the ⋅CH 2 OH radical, thereby advancing the selective C−N bond formation. This work deepens the understanding of the C−N coupling mechanism and offers an intriguing photocatalytic approach for the efficient and sustainable production of C−N compounds.