College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, PR China.
College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, PR China.
Sci Total Environ. 2020 Feb 20;704:135404. doi: 10.1016/j.scitotenv.2019.135404. Epub 2019 Nov 23.
We have successfully synthesized novel Z-scheme CdS/CQDs/g-CN composites with visible-near-infrared light response for the photocatalytic degradation of rhodamine B (RhB), methylene Blue (MB) and phenol. Based on the energy band matching theory, CdS was coupled with g-CN using carbon quantum dots (CQDs) as the electron mediator to form the Z-scheme heterojunctions through a simple calcination process. Compared with the single-phase and binary composites, the Z-scheme CdS/CQDs/g-CN composites not only exhibited enhanced photocatalytic activity and photostability but also realized near-infrared light response. CQDs, as the electron mediator, can shuttle the electrons in the CdS/CQDs/g-CN interface via the Z-scheme electron transfer pathway, which lead to improvements in charge separation and oxidizability of the composites. The Z-scheme electron transfer was verified using various techniques, including PL, EIS, EPR and transient photocurrent response. The mechanism of Z-scheme charge transfer was also proposed for the improved photocatalytic RhB degradation activity. In addition, CQDs can capture near-infrared light through the upconversion fluorescence property, ameliorating the broad- spectrum photocatalytic competence. Therefore, the Z-scheme heterojunction with visible-near-infrared light response was utilized to improve charge separation, oxidizability and solar energy utilization, as well as to provide new insights for the construction of CQDs-based Z-scheme composites for photocatalysis applications.
我们成功合成了具有可见-近红外光响应的新型 Z 型 CdS/CQDs/g-CN 复合材料，用于光催化降解罗丹明 B（RhB）、亚甲基蓝（MB）和苯酚。基于能带匹配理论，通过简单的煅烧过程，CdS 与 g-CN 结合，使用碳量子点（CQDs）作为电子介质形成 Z 型异质结。与单相和二元复合材料相比，Z 型 CdS/CQDs/g-CN 复合材料不仅表现出增强的光催化活性和光稳定性，而且实现了近红外光响应。CQDs 作为电子介质，可以通过 Z 型电子转移途径在 CdS/CQDs/g-CN 界面上穿梭电子，从而提高复合材料的电荷分离和氧化性。通过各种技术，包括 PL、EIS、EPR 和瞬态光电流响应，验证了 Z 型电子转移。还提出了 Z 型电荷转移的机制，以解释改善的光催化 RhB 降解活性。此外，CQDs 可以通过上转换荧光特性捕获近红外光，改善宽光谱光催化能力。因此，利用具有可见-近红外光响应的 Z 型异质结来提高电荷分离、氧化性和太阳能利用率，并为构建用于光催化应用的基于 CQDs 的 Z 型复合材料提供新的思路。
