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Studies on the Molecular Mechanism of Electrochemical Oxygen Evolution Reaction by the Surface luminescence Spectroscopy

表面发光光谱研究电化学析氧反应的分子机理

基本信息

批准号：
61470008
负责人：
NAKATO Yoshihiro
金额：
$ 3.84万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

项目摘要

The majn purpose of this research is to elucidate the molecular mechanism of the photooxidation reaction of water at n-type metal oxide semiconductor electrodes such as n-TiO2 and n-SrTiO_3, mainly by using a method of our recently developed surface luminescence spectroscopy. Through such research, new active electrode materials for electrochemical oxidation reaction of water will be found. We have focused our attention mainly on the mechanism of the photooxidation reaction at the n-TiO, electrode. Though it has often been assumed so far that this reaction proceeds via adsorbed OH radicals produced by the oxidation of adsorbed OH ions by photogenerated holes, it has been concluded in this re- search that this reaction proceeds via interstitial OH radicals produced in the n-TiO_2 bulk close to the surface. Theoretical considerations have sup- ported the latter new mechanism, showing that (1) OH^- ions can be assumed to penetrate into the n-TiO_2 (rutile) bulk through channels present parallel to the c-axis of this crystal, and (2) the resulting interstitial OH- ions in the n-TiO_2 bulk are energetically more easily oxidized than the adsorbed OH- ions, and can be assumed to be oxidized by the photogenerated holes, contrary to the adsorbed OH- ions. The above new mechanism is of great interest, proposing quite a new concept for the understanding of the mechanism of electrode reactions. This mechanism is also very interesting from a practical view-point, in that it indicates the possibility of finding new active electrode materials through the re-investigation of electrode materials on the basis of this new concept. Furthermore, the present finging of this new mechanism is of great value in that it clearly indicates that the surface luminescence spectroscopy is very effective for the in situ investigation of the molecular mechanism of the electrode reactions.

本研究的主要目的是利用我们最近发展的表面发光光谱方法，阐明水在n型金属氧化物半导体电极如n-TiO_2和n-SrTiO_3上光氧化反应的分子机理。通过这些研究，将为水的电化学氧化反应寻找新的活性电极材料，我们主要研究了n-TiO_2电极上的光氧化反应机理。虽然迄今为止，人们通常认为该反应是通过光生空穴氧化吸附OH离子产生的吸附OH自由基进行的，但本研究得出结论，该反应是通过n-TiO_2本体靠近表面处产生的间隙OH自由基进行的。理论分析支持了后一种新的机理，表明（1）OH ~-离子可以通过平行于c轴的通道进入n-TiO_2（金红石）体相，（2）在n-TiO_2体相中产生的间隙OH ~-离子比吸附的OH ~-离子更容易被氧化，并且可以假设被光生空穴氧化，与吸附的OH-离子相反。上述新的机理是非常有趣的，为理解电极反应机理提出了一个相当新的概念。从实用的观点来看，这种机制也是非常有趣的，因为它表明了通过基于这种新概念重新研究电极材料来发现新的活性电极材料的可能性。此外，这一新机理的发现具有重要的价值，因为它清楚地表明，表面发光光谱是非常有效的原位研究的分子机制的电极反应。