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Photocatalytic degradation of volatile chlorinated organic compounds on CuffiO_2 films prepared by size-controlled Cu deposition

尺寸控制铜沉积制备的 CuffiO_2 薄膜光催化降解挥发性氯化有机化合物

基本信息

批准号：
18550180
负责人：
YAMAZAKI Suzuko
金额：
$ 2.56万
依托单位：
Yamaguchi University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18550180/
关键词：
photocatalyst film metal-loaded TiO_2 materials for environmental remediation

项目摘要

Cu-deposited TiO_2 (Cu/TiO_2) films were prepared by photoreduction of Cu(II) in the presence of sodium formate. With the initial Cu(II) concentrations less than 50 mg L 1, the transmittance of the films decreased with an increase in the irradiation time. After the irradiation for 6 hrs, the scanning electron microscopy (SEM) indicated that the most of the Cu particles on the films were 0.51±0.04 μm. On the other hand, when irradiation was conducted in 100 or 150 mg L^<-1> Cu(II) solution, induction periods were observed before the transmittance decreased. The SEM images of the films indicated that Cu particles of 2.6±0.5 μm were deposited isolatedly with much open space in the induction periods. These facts proposed two methods to fabricate the Cu/TiO_2 films. The Cu amounts loaded on the film can be verified by changing the initial Cu(II) concentration less than 50 mg L^<-1> (method A), or changing the irradiation time within the induction period under the Cu(II) concentration above 100 mg L^<-1> (method B). The photocatalytic activities of the Cu/TiO_2 films prepared by both methods followed by calcination at 500℃ were compared in the degradation of methylene blue in aqueous solutions. The films prepared by method B showed a higher photocatalytic activity than a pure TiO_2 under no purging with air. This finding is attributable to higher transmittance of the films and function of the Cu particles as the electron trap which leads to suppression of the recombination between holes and electrons. Photocatalytic degradation of trichloroethylene (TCE) in the gas phase was also performed on the Cu/TiO_2 films prepared by method B. However, the TCE conversion decreased drastically with an increase in the irradiation time. This fact suggests that the accumulation of the by-products significantly affected the performance of the Cu/TiO_2 films.

在甲酸钠存在下通过光还原Cu(II)制备了Cu沉积TiO_2(Cu/TiO_2)薄膜。当初始Cu(II)浓度低于50 mg L 1 时，薄膜的透过率随着照射时间的增加而降低。照射6小时后，扫描电子显微镜(SEM)显示薄膜上的Cu颗粒大部分为0.51±0.04μm。另一方面，当在100或150mg L^-1 Cu(II)溶液中进行照射时，在透射率下降之前观察到诱导期。薄膜的SEM图像表明，在诱导期，2.6±0.5μm的Cu颗粒被孤立地沉积，并且有大量的开放空间。这些事实提出了两种制备Cu/TiO_2薄膜的方法。膜上负载的Cu量可以通过改变初始Cu(II)浓度小于50mg·L^-1(方法A)，或改变Cu(II)浓度高于100mg·L^-1>诱导期内的照射时间(方法B)来验证。比较两种方法制备的Cu/TiO_2薄膜经500℃焙烧后对水溶液中亚甲基蓝的光催化降解活性。方法B制备的薄膜在不进行空气吹扫的情况下表现出比纯TiO_2更高的光催化活性。这一发现归因于薄膜的较高透射率以及铜颗粒作为电子陷阱的作用，从而抑制了空穴和电子之间的复合。对方法B制备的Cu/TiO_2薄膜也进行了气相光催化降解三氯乙烯(TCE)。然而，随着照射时间的增加，TCE转化率急剧下降。这一事实表明副产物的积累显着影响了Cu/TiO_2薄膜的性能。