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学科主题: 物理化学
题名: UV Raman Spectroscopic Studies on Surface Phase Transformation and Photocatalytic Performance of TiO2
作者: Li C(李灿)
会议名称: 21st NAM
会议日期: 2009-6-7
出版日期: 2009-06-07
会议地点: USA
通讯作者: 李灿
部门归属: 五室
主办者: Institute for Interfacial Catalysis
摘要: Introduction TiO2-based photocatalysts have recently attracted much interest for their potential applications to detoxification of environmental pollutants and solar-energy conversion [1]. As a strategy for enhancing the photoactivity of TiO2, coupling of different phases in the surface was proposed [2], meaning the effect of the surface-phase structure. On the other hand, the phase transformation, particularly the surface phase transformation, is one of the most important issues in the practical application of TiO2. The particle size greatly influences the surface and bulk phase transformation of TiO2 particles [3]. It is worth noting that whether the photoactivity or phase transformation of TiO2 is associated with the surface properties. UV Raman spectroscopy has been found to be more sensitive to the surface phase of the samples with strong-absorption in ultraviolet [4]. This advantage of UV Raman spectroscopy makes it possible to correlate the surface crystalline phase with photocatalytic performance. Materials and Methods The anatase TiO2 with different particle sizes were prepared at this laboratory [3, 4]; Preparation of anatase deposited on rutile sample (denoted as TiO2(A)/TiO2(R)) [2]: The rutile TiO2 (Alfa Aesar, 99.8% rutile phase) was used as the support. TiO2(A)/TiO2(R) sample was prepared by a wet impregnation method. Results and Discussion The rutile content in the surface and bulk during the phase transformation can be estimated by UV Raman spectroscopy and XRD, respectively. The proposed model of agglomerated TiO2 particles is shown in Figure 1. The transformation temperature is decreased with the decrease of the initial particle size. Rutile mainly nucleates at the interfaces of the contacting anatase grain (<60 nm) and the free surface, interface and bulk are all likely to work as rutile nucleation sites for particles larger than 60 nm. A correlation (Figure 2) has been found between the surface phase of TiO2 and its photoactivity for hydrogen evolution via the catalytic methanol reforming. It is found that the photoactivity is sensitive to the surface phase and the TiO2 samples with surface anataserutile mixed phase exhibit maximum photoactivity. The effect could be attributed to the formation of surface-phase junction between anatase and rutile, which essentially enhances the charge separation. The junction formed between MoS2 and CdS is supposed to be responsible for the enhanced photocatalytic activity of MoS2/ CdS. [5], the result further confirms the effect of the surface junction on photocatalytic activity. Significance The surface sensitivity of UV Raman spectroscopy can be widely applied in the investigation of surface properties and catalytic performance of catalysts. The importance of surface-phase junction provides a possible strategy to develop high-activity photocatalysts for both environmental protection and solar energy utilization.
语种: 中文
内容类型: 会议论文
URI标识: http://cas-ir.dicp.ac.cn/handle/321008/113842
Appears in Collections:中国科学院大连化学物理研究所_会议论文

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Recommended Citation:
Li C. UV Raman Spectroscopic Studies on Surface Phase Transformation and Photocatalytic Performance of TiO2[C]. 见:21st NAM. USA. 2009-6-7.
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