Faculty of Chemistry, Kharazmi University, Tehran, Iran.
Environ Sci Pollut Res Int. 2022 Aug;29(37):56490-56501. doi: 10.1007/s11356-022-19777-9. Epub 2022 Mar 26.
Photo-treatment of water is a promising environmentally friendly process that provides clean water and makes wastewater reusable in industry. Thus, efforts toward finding highly efficient photocatalysts have gained a huge attention to remove the organic contaminants in water. Quantum dots (QDs) are extensively utilized for photocatalytic remediation regarding their prominent optical, electrical, and chemical properties. Herein, we report the highly efficient and environmentally friendly synthesis of CoO-QDs-based graphene quantum dots (GQDs) and infinite coordination polymer comprising Zn nodes (Zn-ICP) nanocomposites as active and robust photocatalysts for photo-assisted water treatment. The pristine CoO-QDs, GQDs, and Zn-ICP showed lower activity under visible light. However, after functionalization of GQDs and Zn-ICP with CoO-QDs, the activity increased, and more photocatalytic efficiency was achieved. For instance, Zn-ICP, GQDs, CoO-QDs, CoO-QDs/Zn-ICP, and CoO-QDs/GQD degraded 21, 19, 52, 73, and 83% of rhodamine B (RhB) and 34, 46, 50, 73, and 76% of methylene blue (MB) after 60 min. The high photocatalytic efficiency was ascribed to the conjugation of CoO-QDs with GQDs and Zn-ICP which causes efficient absorption of visible light. The existence of CoO-QDs was found to be essential not only for effective charge separation but also widening the region of light absorption followed by increase in photocatalytic performances. Charge separation in photocatalytic reactions, energy levels of nanocomposites, and mechanism of the photocatalytic process were investigated by photoluminescence spectra (PL), Mott-Schottky, electrochemical impedance (EIS), and diffuse reflectance UV-Vis spectroscopy (DRS).
水的光处理是一种很有前途的环保工艺，它提供了清洁的水，并使工业废水能够重复使用。因此，人们努力寻找高效的光催化剂，以去除水中的有机污染物。量子点（QDs）由于其突出的光学、电学和化学性质，被广泛用于光催化修复。在此，我们报告了基于 CoO-QDs 的石墨烯量子点（GQDs）和由 Zn 节点（Zn-ICP）组成的无限配位聚合物的高效、环保合成，作为用于光辅助水处理的活性和强韧的光催化剂。原始的 CoO-QDs、GQDs 和 Zn-ICP 在可见光下活性较低。然而，在 GQDs 和 Zn-ICP 与 CoO-QDs 功能化后，活性增加，实现了更高的光催化效率。例如，Zn-ICP、GQDs、CoO-QDs、CoO-QDs/Zn-ICP 和 CoO-QDs/GQD 分别降解了 21%、19%、52%、73%和 83%的罗丹明 B（RhB）和 34%、46%、50%、73%和 76%的亚甲基蓝（MB），60 分钟后。高的光催化效率归因于 CoO-QDs 与 GQDs 和 Zn-ICP 的结合，这导致了可见光的有效吸收。发现 CoO-QDs 的存在不仅对于有效的电荷分离是必要的，而且还拓宽了光吸收区域，从而提高了光催化性能。光催化反应中的电荷分离、纳米复合材料的能级以及光催化过程的机制通过光致发光光谱（PL）、Mott-Schottky、电化学阻抗（EIS）和漫反射紫外可见光谱（DRS）进行了研究。
