CdSQDs/TiO2复合材料的制备及光催化性能

Preparation of CdS Quantum Dot Composite Photocatalytic Material CdSQDs/TiO and Its Degradation of Organic Pollutant RhB

采用溶胶-凝胶法制备了一种CdS量子点(QDs)与TiO2的复合材料(CdSQDs/TiO2)。该材料具有较高的光催化活性和稳定性,在250 W金卤灯(波长>420 nm)照射下催化降解初始浓度为10μmol/L的模型污染物罗丹明B(RhB),反应120 min,RhB的降解率达到97%;反应240 min,RhB的TOC去除率约34%;经过8次循环使用,其光催化活性几乎没有损失。5,5-二甲基1-吡咯啉N-氧化物(DMPO)捕获自由基的电子顺磁共振(ESR)实验证明,光催化过程产生了·O^2-和·OH自由基,正是这些活性氧物质导致了RhB的降解。根据实验事实提出的光催化反应机理表明,CdSQDs和TiO2之间产生了协同作用,促进了光电子的转移,降低了光电子与空穴复合的几率,从而提高了光催化效率。

In this paper,a composite material composed of CdS quantum dot and TiO2 was prepared using sol-gel method.This material presents a high photocatalytic activity and stability.The degradation rate of RhB with an initial concentration of 10μmol/L reached 97%at 120 min and the TOC removal was about 34%at 240 min under the irradiation of 250 W metal halide lamp(λ>420 nm).After being cyclically reused for 8 times,almost no loss of the photocatalytic activity was obtained.Electron spin resonance(ESR)experiment in which radicals were captured by 5,5-dimethyl-1-pyrroline N-oxide(DMPO)proved that·O^2-and·OH radicals were generated in the photocatalytic process,which led to the degradation of RhB.A photocatalysis mechanism proposed in terms of experimental facts indicates that the synergistic effect between CdSQDs and TiO2 facilitates the photogenerated electrons transfer and reduces the probability of the recombination of photoelectrons and holes,thus the photocatalytic efficiency is improved.