Xu Mingkai, Wang Ruizhao, Fu Haoyang, Shi Yanbiao, Ling Lan
State Key Laboratory for Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Proc Natl Acad Sci U S A. 2024 Mar 19;121(12):e2318787121. doi: 10.1073/pnas.2318787121. Epub 2024 Mar 13.
Manipulating exciton dissociation and charge-carrier transfer processes to selectively generate free radicals of more robust photocatalytic oxidation capacity for mineralizing refractory pollutants remains challenging. Herein, we propose a strategy by simultaneously introducing the cyano-group and Na into graphitic carbon nitride (CN) to obtain CN-Cy-Na, which makes the charge-carrier transfer pathways the dominant process and consequently achieves the selective generation of free radicals. Briefly, the cyano-group intensifies the local charge density of CN, offering a potential well to attract the hole of exciton, which accelerates the exciton dissociation. Meanwhile, the separated electron transfers efficiently under the robust built-in electric field induced by the cyano-group and Na, and eventually accumulates in the heptazine ring of CN for the following O reduction due to the reinforced electron sink effect caused by Na. As a result, CN-Cy-Na exhibits 4.42 mmol L h productivity with 97.6% selectivity for free radicals and achieves 82.1% total organic carbon removal efficiency in the tetracycline photodegradation within 6 h. Additionally, CN-Cy-Na also shows outstanding photodegradation efficiency of refractory pollutants, including antibiotics, pesticide plastic additives, and dyes. This work presents an innovative approach to manipulating the exciton effect and enhancing charge-carrier mobility within two-dimensional photocatalysts, opening an avenue for precise control of free radical generation.
操纵激子解离和电荷载流子转移过程以选择性地产生具有更强光催化氧化能力的自由基来矿化难降解污染物仍然具有挑战性。在此，我们提出了一种策略，即通过同时将氰基和钠引入石墨相氮化碳（CN）中来获得CN-Cy-Na，这使得电荷载流子转移途径成为主导过程，从而实现自由基的选择性生成。简而言之，氰基增强了CN的局部电荷密度，提供了一个势阱来吸引激子的空穴，这加速了激子解离。同时，分离出的电子在氰基和钠诱导的强大内建电场下有效转移，最终由于钠引起的增强电子阱效应而在CN的七嗪环中积累，用于后续的O还原。结果，CN-Cy-Na在6小时内对四环素的光降解中表现出4.42 mmol L h的产率，对自由基的选择性为97.6%，总有机碳去除效率达到82.1%。此外，CN-Cy-Na对包括抗生素、农药塑料添加剂和染料在内的难降解污染物也表现出出色的光降解效率。这项工作提出了一种创新方法来操纵激子效应并增强二维光催化剂内的电荷载流子迁移率，为精确控制自由基生成开辟了一条途径。
