Feng Jin, Liu Guokui, Yuan Shiling, Ma Yuchen
School of Chemistry and Chemical Engineering, Shandong University, 250100, China.
Phys Chem Chem Phys. 2017 Feb 15;19(7):4997-5003. doi: 10.1039/c6cp08622e.
The coupling of carbon nanodots (C-Dots) with graphitic carbon nitride (g-CN) has been demonstrated to boost the overall photocatalytic solar water splitting efficiency. However, the understanding on the role of the C-Dots and how the structure of C-Dots influences the photocatalytic reaction is still limited. In this work, we investigate the excited states of some C-Dot/g-CN composites with the C-Dots containing different functional groups including -OH, -CHO and -COOH by first-principles many-body Green's function theory. It is found that the increase of efficiency can be ascribed to the high separation rate and the low recombination rate of the electron-hole pair benefiting from the emergence of the charge-transfer excited state between the C-Dots and g-CN. Functional groups on the C-Dots play a crucial role in determining the charge transfer direction, active sites for reduction reaction and oxidation reaction of water, and whether the reaction is a four-electron process or a two-electron/two-electron process. These results can provide guidance for the design and optimization of the C-Dots for heterojunction photocatalysts.
碳纳米点（C点）与石墨相氮化碳（g-CN）的耦合已被证明可提高光催化太阳能水分解的整体效率。然而，对于C点的作用以及C点结构如何影响光催化反应的理解仍然有限。在这项工作中，我们通过第一性原理多体格林函数理论研究了一些含有不同官能团（包括-OH、-CHO和-COOH）的C点/g-CN复合材料的激发态。研究发现，效率的提高可归因于电子-空穴对的高分离率和低复合率，这得益于C点和g-CN之间电荷转移激发态的出现。C点上的官能团在确定电荷转移方向、水还原反应和氧化反应的活性位点以及反应是四电子过程还是两电子/两电子过程方面起着关键作用。这些结果可为异质结光催化剂中C点的设计和优化提供指导。
