A STUDY ON PHOTOACTIVATION OF FUEL CELLS

光合作用被定义为从光子到化学势的能量转换，这些化学势积累在类囊体膜上。在这项研究项目中，人们试图制备具有光活性的超薄膜，以构建“人造类囊体膜”。本研究由两部分组成：作为模型体系，二氧化钛粉末被浸渍在Nafion膜(固体聚合物电解质)的表面。铂网被附着在Nafion薄膜的两个表面上，以构建在二氢气体存在下的燃料电池。当电池被紫外光照射时，甲醇水溶液可以用作燃料。光电流最高可达2 mA/cm~2。该光电流归因于二氧化钛的光活化。甲醇的光催化氧化在薄膜表面释放出二氢，从而实现了燃料电池的光活化。部分光电流可以归因于从二氧化钛导带到电极的直接电子流动。通过在水面上显影聚合物溶液，制备了一种新型的超薄聚合物薄膜。聚氯乙烯在四氢呋喃-甲苯混合溶剂中得到了最好的薄膜(厚度为25 nm)，并在一个表面选择性地浸渍了两叶性三联吡啶配合物。通过对薄膜表面光学二次谐波(SHG)的观察，证实了薄膜的非对称性。此外，膜表面的Ru络合物在水溶液中起到了光氧化还原的催化作用。

Photosynthesis is defined as an energy conversion from photon into chemical potentials, which are accumulated across thylakoid membrane. In this research project, attempts have been made to prepare photoactive, ultrathin films for construction of "artificial thylakoid membrane" . The study was consisted of two parts :As a model system, titanium dioxide powder was impregnated on the surface of Nafion film (solid polymer electrolyte). Platinum meshes were attached to both surfaces of the Nafion film to construct a fuel cell in the presence of dihydrogen gas. Aqueous methanol solutions could be used as a fuel, when the cell was illuminated with ultraviolet light. The photocurrent reached upto 2 mA/cm^2. The photocurrent was ascribed to photoactivation of titanium dioxide. Photocatalytic oxidation of methanol liberated dihydrogen at the film surface so that photoactivation of fuel cell was achieved. A part of the photocurrents could be ascribed to direct electron-flow from conduction band of the titanium dioxide to the electrode.A novel, ultrathin polymer film was prepared by developing polymer solutions on water surface. Polyvinylchloride in THF-toluene mixed solvent afforded the best thin film (25 nm in thickness), which was selectively impregnated with amphiphylic ruthenium trisbipyridine complexes at one surface. Asymmetric property of the film was confirmed by observation of optical second harmonic generation (SHG) at the surface. In addition, the ruthenium complexes at the membrane surface were verified to act as photoredox catalyst in aqueous solutions.