MIL-53(Fe)/g-C3N4复合材料的制备及其光催化性能
Preparation and photocatalytic properties of MIL-53(Fe)/g-C3N4 composites
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摘要: 本文采用溶剂热法制备了MIL-53(Fe)与g-C3N4不同质量比(0.80、2.40、4.00)的MIL-53(Fe)/g-C3N4复合材料(分别标记为MIL-53(Fe)/g-C3N4-1、MIL-53(Fe)/g-C3N4-2、MIL-53(Fe)/g-C3N4-3),并采用X射线衍射仪(XRD)、傅里叶变换红外光谱(FT-IR)、扫描电子显微镜(SEM)、比表面积分析仪(BET)、荧光光谱(PL)和紫外-可见漫反射光谱(UV-vis DRS)对其结构及形貌、吸附特性和光化学特性等进行了表征.在可见光(λ﹥420 nm)的光照条件下,研究了MIL-53(Fe)/g-C3N4复合材料对罗丹明B(rhodamine B,RhB)和小分子农药草甘膦(glyphosate)有机污染物的光催化降解特性,发现MIL-53(Fe)/g-C3N4-2在60 min内对RhB的降解率达到99.73%(k=0.10 min-1),降解速率分别是g-C3N4(k=0.06 min-1)和MIL-53(Fe)(k=0.02 min-1)的1.67倍和5.00倍.同样在可见光照射下,MIL-53(Fe)/g-C3N4-2也可以有效降解草甘膦,在360 min内对草甘膦的降解率为41.47%(k=1.44×10-3 min-1),降解速率约是g-C3N4(k=2.43×10-4 min-1)和MIL-53(Fe)(k=2.39×10-4 min-1)的6.00倍.结果表明,当MIL-53(Fe)与g-C3N4的复合质量比为2.40时,所制备的MIL-53(Fe)/g-C3N4复合材料在可见光下具有最佳的光催化活性,这归因于MIL-53(Fe)和g-C3N4的有效复合,促进了光生电子空穴的分离,还增加了比表面积,提高了光催化活性.结合自由基捕获实验,发现该催化体系降解过程中超氧自由基(·O2-)和空穴(h+)占主导作用.
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关键词:
- MIL-53(Fe) /
- 石墨型氮化碳 /
- 光催化降解
Abstract: MIL-53(Fe)/g-C3N4 composites with different mass ratios (0.80, 2.40, 4.00) of MIL-53(Fe)/g-C3N4-1, MIL-53(Fe)/g-C3N4-2 and MIL-53(Fe)/g-C3N4-3 were prepared by solvothermal method. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscope (SEM), specific surface area analyzer (BET), fluorescence spectrum (PL) and UV-visible diffuse reflectance spectroscopy (UV-vis DRS) were used to characterize their structure and morphology, adsorption characteristics and photochemical characteristics. The photocatalytic degradation performance of Rhodamine B (RhB) and small molecule pesticide (Glyphosate) by the as-prepared composites were studied under visible light (λ> 420 nm). It was found that the degradation efficiency of RhB reached 99.73% by MIL-53(Fe)/g-C3N4-2 (k=0.10 min-1) within 60 min, and the degradation rate was 1.67 times and 5.00 times of that of g-C3N4 (k=0.06 min-1) and MIL-53(Fe) (k=0.02 min-1) respectively. Meanwhile, under visible light irradiation, MIL-53(Fe)/g-C3N4-2 could effectively degrade glyphosate. The degradation efficiency of glyphosate was 41.47% (k=1.44×10-3 min-1) within 360 min, and the degradation rate was about 6 times of that of g-C3N4 (k=2.43×10-4 min-1) and MIL-53(Fe) (k=2.39×10-4 min-1). The experimental results showed that when the composite mass ratio of MIL-53(Fe) and g-C3N4 was 2.40, the prepared MIL-53(Fe)/g-C3N4 composite had the best photocatalytic activity in visible light. This was attributed to the effective combination of MIL-53(Fe) and g-C3N4, which promoted the separation of photogenic electron holes, increased the specific surface area and consequently, improved the photocatalytic activity. Combining with the free radical capture experiments, it was found that both superoxide free radical (·O2-) and hole (h+) played a dominant role during the degradation process of the catalytic system.-
Key words:
- MIL-53(Fe) /
- graphite carbon nitride /
- photodegradation
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