Liu Hu, Shen Mengqi, Zhou Peng, Guo Zhi, Liu Xinyang, Yang Weiwei, Gao Manyi, Chen Min, Guan Huanqin, Padture Nitin P, Yu Yongsheng, Guo Shaojun, Sun Shouheng
MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150001, China.
Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA.
Nanoscale. 2021 May 27;13(20):9315-9321. doi: 10.1039/d1nr01940f.
Developing an efficient single component photocatalyst for overall water splitting under visible-light irradiation is extremely challenging. Herein, we report a metal-free graphitic carbon nitride (g-CxN4)-based nanosheet photocatalyst (x = 3.2, 3.6, or 3.8) with melem rings conjugated by Schiff-base bonds (N[double bond, length as m-dash]C-C[double bond, length as m-dash]N). The presence of the conjugated Schiff-base bond tunes the band gap of g-CxN4 and, more importantly, serves as an electron sink to suppress electron-hole pair recombination. The projected density of states (PDOS) calculations suggest that the melem ring and Schiff-base bond act as oxidizing and reducing centers, respectively, for photocatalytic water splitting. As a result, g-CxN4, in particular g-C3.6N4, can catalyze overall water splitting without the need for any co-catalyst or sacrificial donor. Under visible light (>420 nm wavelength) irradiation, g-C3.6N4 catalyzes the overall water splitting with H2 and O2 generation rates of 75.0 and 36.3 μmol h-1 g-1, respectively. g-C3.6N4 is the most efficient single-component photocatalyst ever reported for overall water splitting. Our studies demonstrate a new approach for tuning the bandgap and the electronic structure of graphitic carbon nitride for maximizing its photocatalytic performance for water splitting, which will be important for hydrogen generation and for energy applications.
开发一种在可见光照射下用于整体水分解的高效单组分光催化剂极具挑战性。在此，我们报道了一种基于无金属石墨相氮化碳（g-CxN4）的纳米片光催化剂（x = 3.2、3.6或3.8），其蜜勒胺环通过席夫碱键（N=C-C=N）共轭。共轭席夫碱键的存在调节了g-CxN4的带隙，更重要的是，它作为电子阱抑制电子-空穴对的复合。态密度投影（PDOS）计算表明，蜜勒胺环和席夫碱键分别作为光催化水分解的氧化中心和还原中心。因此，g-CxN4，特别是g-C3.6N4，无需任何助催化剂或牺牲供体就能催化整体水分解。在可见光（波长>420 nm）照射下，g-C3.6N4催化整体水分解，H2和O2的生成速率分别为75.0和36.3 μmol h-1 g-1。g-C3.6N4是迄今为止报道的用于整体水分解的最有效的单组分光催化剂。我们的研究展示了一种调节石墨相氮化碳带隙和电子结构以最大化其水分解光催化性能的新方法，这对制氢和能源应用具有重要意义。
