宽光谱响应CQDs/TiO_2复合材料的制备及其光催化活性

Preparation and Photocatalytic Activity of CQDs/TiO_2 Composites with Wide Spectral Response

通过超声法制备了CQDs/TiO_2复合光催化材料,采用XRD、FT-IR、HRTEM、DRS等手段对复合光催化材料的组成、结构和光学特性进行了表征。结果表明CQDs可以成功负载到TiO_2表面,并使催化剂的吸收带边产生红移。以罗丹明B(Rh B)为目标降解物,模拟太阳光和LED单色光为光源,考察了不同CQDs负载量对TiO_2光催化性能的影响,结果表明CQDs/TiO_2在模拟太阳光下展现出出色的光催化活性,当CQDs浓度为1.5 mg/m L时光催化降解效率达到最佳,研究还发现所制备的CQDs/TiO_2复合材料对光谱的可利用范围大大增宽,甚至在850 nm波长光照下依然可以发挥光催化作用。进一步对样品进行荧光及瞬态光电流表征,结果表明CQDs/TiO_2的宽光谱响应主要来源于CQDs的上转换荧光性质。

The CQDs/TiO2 composites photocatalysts are prepared by an ultrasonic method. The compositions,structures and optical properties of CQDs/TiO2 composites are detected through XRD,FTIR,HRTEM and DRS. The results indicate CQDs can successfully attach to the surface of TiO2 and result in a red shift of the absorption edge of catalysts. The photocatalytic activity of the obtained materials with different concentration of CQDs are evaluated by degradation of rhodamine B（Rh B） under simulated sunlight and monochromatic light irradiation. The results show the CQDs/TiO2 composites exhibit excellent ability of photocatalytic activity under simulated sunlight and the activity get to the best when the concentration of CQDs is 1. 5 mg/m L. Moreover,it is found the available range of spectrum of CQDs/TiO2 composites are significantly broadened, and the CQDs/TiO2 even showed effective photocatalytic performance under 850 nm light irradiation. The results of PL and transient photocurrent responses indicate the wide spectral response of CQDs/TiO2 composites can be ascribed to the unique upconverted photoluminescence behavior of CQDs.