碳点/CeVO_(4)纳米复合物协同可见光活化过一硫酸盐降解盐酸四环素

CDs/CeVO_(4)nanohybrids synergistic visible light for activation of peroxymonosulfate toward tetracycline degradation

CeVO_(4)因其对可见光较低的利用率和光生电子空穴对易于复合的缺点限制其在光催化领域中的应用。碳点(CDs)具有独特的π共轭结构赋予其优异的光生电子存储和转移能力。本研究采用水热和共沉淀两步法成功制备出CDs与CeVO_(4)的纳米复合物(CDs/CeVO_(4)),在掺入CDs后,其光生载流子的转移和分离效率得到有效提高。在可见光照射下,CDs/CeVO_(4)能高效活化过一硫酸盐(PMS)降解盐酸四环素(TC),反应60 min后对TC的降解率达到90%。反应速率常数是CeVO_(4)的4.1倍(0.03815 min^(−1))。XPS、紫外可见漫反射光谱和时间分辨荧光光谱测试结果表明,CDs/CeVO_(4)相比于CeVO_(4)带隙变窄,可见光吸收能力增强,荧光寿命是CeVO_(4)的15.1倍(7.10 ns)。电子顺磁共振光谱(EPR)与XPS测试结果相互印证掺入CDs的纳米复合物中存在丰富的氧空位,进一步增强其活化PMS能力。活性物质捕获实验表明,h^(+)、SO_(4)^(-)和•OH是反应体系中的活性物质,在此基础上提出了该体系可能的降解机制。CDs/CeVO_(4)表现出良好的稳定性,经过5次循环实验后,仍表现出良好的催化性能。CDs/CeVO_(4)协同可见光活化PMS降解水中有机污染物为废水治理提供一种新的方法和思路。

The limited absorption of visible light and high recombination rate of photogenerated electron-hole pairs impede the practical application of CeVO_(4)in photocatalysis.The uniqueπ-conjugated structure of carbon dots(CDs)endows them with exceptional capabilities for the storing and transferring photogenerated electrons.Herein,CDs/CeVO_(4)was successfully synthesized by two-step method of hydrothermal and co-precipitation,resulting in a significant enhancement of photogenerated carrier transfer and separation efficiency with the incorporation of CDs.Under visible light irradiation,CDs/CeVO_(4)exhibit enhanced activity towards peroxymonosulfate(PMS)for the degradation of tetracycline hydrochloride(TC),resulting in a 90%degradation rate of TC after 60 min of reaction.The reaction rate constant is 4.1 times higher than that of CeVO_(4).XPS,UV-Vis DRS,and time-resolved fluorescence spectra demonstrate that CDs/CeVO_(4)exhibits a narrower band gap,an enhanced capacity for absorbing visible light,and a 15.1-fold increase in the fluorescence lifetime compared to CeVO_(4).The results of electron paramagnetic resonance(EPR)and XPS tests confirm the presence of abundant oxygen vacancies in CDs/CeVO_(4),thereby further enhancing their capacity for activating PMS.Capture experiments of active substances show that h^(+),SO_(4)^(-)and•OH are the active species in the reaction system,and a plausible degradation mechanism was proposed.After five cycles of experiments,the degradation rate decreased slightly,showing good photocatalytic performance.This work provides a new strategy for the degradation of organic pollutants in wastewater.