In this work, a new visible-light driven photocatalyst, carbon quantum dots (CQDs)/KNbO₃ composite, is successfully prepared via hydrothermal and mixed-calcination methods Multiple techniques, such as X-ray diffraction (XRD) spectroscopy, scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray (EDX) spectroscopy, fourier-transform infrared (FT-IR) spectroscopy, UV–vis diffuse reflectance spectroscopy and photoluminescence (PL) spectroscopy, are applied to investigate the morphologies, structures and optical properties of the prepared CQDs/KNbO₃ composites. The photocatalytic activity of CQDs/KNbO₃ composites is evaluated via degradation of crystal violet dye as target organic pollutant with simultaneous hydrogen production under visible-light irradiation. The results show that the CQDs/KNbO₃ composites exhibit much higher photocatalytic activity than the KNbO₃. It is ascribed to the presence of the CQDs as co-catalyst on the surface of KNbO₃ particles, forming much more active sites for trapping electrons and promoting the separation of photo-generated electron-hole pairs. In addition, the CQDs can absorb visible-lights and emit the ultraviolet-lights to activate the wide band-gap KNbO₃. The study of reusability shows that the CQDs/KNbO₃ can be effectively recycled for four repetitive cycles and maintain a higher level of photocatalytic activity. In conclusion, the present work designs an effectively visible-light driven photocatalyst, which can be applied in photocatalytic degradation of organic pollutants with simultaneous hydrogen evolution.

在这项工作中，成功地通过水热和混合煅烧方法成功地制备了一种新型的可见光驱动的光催化剂，碳量子点（CQDs）/ KNbO ₃复合材料，例如X射线衍射（XRD）光谱，扫描电子显微镜等多种技术。 （SEM），透射电子显微镜（TEM），X射线光电子能谱（XPS），能量色散X射线（EDX）光谱，傅立叶变换红外（FT-IR）光谱，UV-vis漫反射光谱和光致发光（ PL）光谱学用于研究制备的CQDs / KNbO ₃复合材料的形貌，结构和光学性质。CQDs / KNbO ₃的光催化活性通过降解作为目标有机污染物的结晶紫染料并在可见光照射下同时产氢，可对复合材料进行评估。结果表明，CQDs / KNbO ₃复合材料表现出比KNbO ₃高得多的光催化活性。这归因于CQDs作为助催化剂存在于KNbO ₃颗粒的表面上，形成了更多的活性位点以捕获电子并促进了光生电子-空穴对的分离。另外，CQD可吸收可见光并发射紫外光以激活宽带隙KNbO ₃。可重用性研究表明，CQDs / KNbO ₃可以有效地循环使用四个重复周期，并保持较高水平的光催化活性。总之，本工作设计了一种有效的可见光驱动的光催化剂，该催化剂可用于光催化降解有机污染物并同时释放出氢气。