Simultaneously Tuning Charge Separation and Oxygen Reduction Pathway on Graphitic Carbon Nitride by Polyethylenimine for Boosted Photocatalytic Hydrogen Peroxide Production

作者：Xiangkang Zeng, Yue Liu, Yuan Kang, Qinye Li, Yun Xia, Yinlong Zhu, Huilin Hou, Md Hemayet Uddin, Thomas R. Gengenbach, Dehua Xia, Chenghua Sun, David McCarthy, Ana Deletić, Jiaguo Yu, Xiwang Zhang · 发表于：ACS Catalysis · 年份：2020 · DOI：10.1021/acscatal.9b05247 · 被引用次数：486 · 研究领域：Advanced Photocatalysis Techniques、Gas Sensing Nanomaterials and Sensors、ZnO doping and properties

The synthesis of hydrogen peroxide (H 2 O 2 ) from H 2 O and O 2 by metal-free photocatalysts (e.g., graphitic carbon nitride, C 3 N 4 ) is a potentially promising approach to generate H 2 O 2 . However, the photocatalytic H 2 O 2 generation activity of the pristine C 3 N 4 in pure H 2 O is poor due to unpropitious rapid charge recombination and unfavorable selectivity. Herein, we report a facile method to boost the photocatalytic H 2 O 2 production by grafting cationic polyethylenimine (PEI) molecules onto C 3 N 4 . Experimental results and density functional theory (DFT) calculations demonstrate PEI can tune the local electronic environment of C 3 N 4 . The unique intermolecular electronic interaction in PEI/C 3 N 4 not only improves the electron–hole separation but also promotes the two-electron O 2 reduction to H 2 O 2 via the sequential two-step single-electron reduction route. With the synergy of improved charge separation and high selectivity of two-electron O 2 reduction, PEI/C 3 N 4 exhibits an unexpectedly high H 2 O 2 generation activity of 208.1 μmol g –1 h –1, which is 25-fold higher than that of pristine C 3 N 4 . This study establishes a paradigm of tuning the electronic property of C 3 N 4 via functional molecules for boosted photocatalysis activity and selectivity.