Enhancing Photocatalytic‐Transfer Semi‐Hydrogenation of Alkynes Over Pd/C<sub>3</sub>N<sub>4</sub> Through Dual Regulation of Nitrogen Defects and the Mott–Schottky Effect
Yaning Hu, Shuo Zhang, Zedong Zhang, Hexin Zhou, Bing Li, Zhiyi Sun, Xuemin Hu, Wenxiu Yang, Xiaoyan Li, Yu Wang, Shuhu Liu, Dingsheng Wang, Jie Lin, Wenxing Chen, Shuo Wang
Abstract
Abstract The selective hydrogenation of alkynes is an important reaction; however, the catalytic activity and selectivity in this reaction are generally conflicting. In this study, ultrafine Pd nanoparticles (NPs) loaded on a graphite‐like C 3 N 4 structure with nitrogen defects (Pd/DCN) are synthesized. The resulting Pd/DCN exhibits excellent photocatalytic performance in the transfer hydrogenation of alkynes with ammonia borane. The reaction rate and selectivity of Pd/DCN are superior to those of Pd/BCN (bulk C 3 N 4 without nitrogen defects) under visible‐light irradiation. The characterization results and density functional theory calculations show that the Mott–Schottky effect in Pd/DCN can change the electronic density of the Pd NPs, and thus enhances the hydrogenation selectivity toward phenylacetylene. After 1 h, the hydrogenation selectivity of Pd/DCN reaches 95%, surpassing that of Pd/BCN (83%). Meanwhile, nitrogen defects in the supports improve the visible‐light response and accelerate the transfer and separation of photogenerated charges to enhance the catalytic activity of Pd/DCN. Therefore, Pd/DCN exhibits higher efficiency under visible light, with a turnover frequency (TOF) of 2002 min −1 . This TOF is five times that of Pd/DCN under dark conditions and 1.5 times that of Pd/BCN. This study provides new insights into the rational design of high‐performance photocatalytic transfer hydrogenation catalysts.