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Study of Photophysical Process and Photocatalytic Activity of Anchored Catalyst Prepared by thev Sol-Gel Method

溶胶-凝胶法制备锚定催化剂的光物理过程及光催化活性研究

基本信息

批准号：
02805099
负责人：
FUJII Tsuneo
金额：
$ 1.15万
依托单位：
Shinshu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02805099/
关键词：
Sol-Gel Method Mixed Metal Oxides Photocatalyst Photophysics Anchored Catalyst Fluorescence Spectra Photo CVD Photoprobe 蛍光スペクトル光CVD

项目摘要

The absortion, fluorescence, and fluorescence-excitation spectra of some aromatic photoprobe molecules(l-naphthol, benzoqunolines, rhodamine VB, fluorescein, and pyrene)have been observed along with the progress of the sol-gel reaction of SI-AI and Si-Ti mixed alkoxides. The spectral changes during the sol-gel process reflected the changes of the polarity, microviscosity, and other chemical and physical properties around the photoprobes of the reaction specimes. In a case of small fraction of AI, gelation occurred relatively slow and polarity and microviscosity around the photoprobe molecules increased relatively fast. On the other hand, the reverse chemical and physical phenomena are observed in a case of large fraction of AI. In a case of acid catalyst, hydrolysis proceeded fast and the rate determing reaction is condensation step. On the other hand, in a case of basic catalyst, the condensation proceeds fast and the rate determining step is hydrolysis. Observation of the fluorescence spectra of aromatic molecules is a useful photophysical and photochemical probe for studying the sol-gel-xerogel transition of metal alkoxides on a molecular level.The thermal stability, similar to the photostability, of aromatic molecules encapsulated in xerogel state prepared by the sol-gel method is one of the important point for the utility of functional materials. We found that the encapsulated rhodamine B and fluorescein molecules have increased thermal stability than in air circumstance. This enhancement can be sttributed to the prevention of the permeation of oxygen into the pores of the prepared silica gel.Excimer-like fluorescence of pyrene during the sol-gel reaction disappeared before gelation, but the fluorescence intensity became strong in encapsulated state into pores of the Si-Ti and SI-AI. This striking phenomenon can be attributable to the adsorption of two molecules at Ti site and 1 : 1 complex formation between aromatic molecules and AI.

沿着Si-Al和Si-Ti混合醇盐溶胶-凝胶反应的进行，观察到了一些芳香族光探针分子（1-萘酚、苯并喹啉、罗丹明VB、荧光素和芘）的吸收光谱、荧光光谱和荧光激发光谱。溶胶-凝胶过程中的光谱变化反映了反应体系光探针周围的极性、微粘度等物理化学性质的变化。在一个小部分的AI的情况下，凝胶化发生相对缓慢，极性和微粘度周围的光探针分子增加相对较快。另一方面，在大部分AI的情况下观察到相反的化学和物理现象。在酸性催化剂作用下，水解反应进行得较快，反应的速率控制步骤为缩合反应。另一方面，在碱性催化剂的情况下，缩合进行得快，并且速率决定步骤是水解。芳香族分子的荧光光谱是从分子水平研究金属醇盐溶胶-凝胶-干凝胶转变的一种有用的光化学和物理探针，而利用溶胶-凝胶法制备的干凝胶包裹芳香族分子的热稳定性与光稳定性类似，是功能材料实用化的一个重要方面。结果表明，包封的罗丹明B和荧光素分子的热稳定性比在空气中有所提高。芘在溶胶-凝胶反应过程中的类准分子荧光在凝胶化前消失，但在Si-Ti和SI-Al的孔中，荧光强度在包封状态下变强。这是由于两个分子在Ti位上的吸附以及芳香分子与Al形成1：1络合物的结果。