Photorechargeability and charge transfer characteristics in titanium oxide photocatalytic films with selforganized nano structure

光充电电池是一种新型的太阳能装置，它将光子能转换为电化学能，并将其原位储存在单个电池中。由于充电不需要任何外部电路，因此有望应用于分离的小型辅助电池。本研究利用氢等离子体还原法和光电化学腐蚀法在具有自组织纳米结构的二氧化钛薄膜表面制备了低能量存储点。当刻蚀在薄膜表面产生氧缺陷时，薄膜的光电动势和光充电量降低，而当刻蚀不产生氧缺陷时，薄膜的光电动势和光充电量迅速增加。如果多孔膜用相同的方式处理，协同效应是预期的光充电性。接下来，在化学气相沉积中的晶须状薄膜的晶体生长的控制，试图通过外部电场和紫外光。预期通过暴露具有自组织纳米结构的晶体表面上的高光活性位点来提高效率。晶体生长的变化与外部的激发，观察到的光充电性的影响是小的。高外部激励的进一步研究正在进行中。

The photorechargeable battery is a new solar device that converts photon energy to electrochemical energy and stores it in situ in a single cell. Since any external electrical circuits are not necessary for the charge, the application to separated small auxiliary batteries is expected. However, because of the upper limit of the photo-emf, realization of an efficient photocharge is a problem to be solved.In this research, low energy storage sites were created on the surface of titanium oxide thin films with self-organized nano-structure by the reduction with hydrogen plasma and photo-electrochemical etching. The photo-emf and the photorechargeable quantity reduced in the films when oxygen defects were produced on the surface by the etching, while they showed a rapid increase when the etching was not associated with oxygen defects. If porous films are treated with the same manner, synergistic effect is expected for the photorechargeablity.Next, the control of the crystal growth was attempted for whisker-shaped thin films by an external electric field and UV light in chemical vapor deposition. An increase of efficiency was expected by the exposure of the sites with high photo activity on the crystal surface with self-organized nano-structure. The change in the crystal growth was observed with the external excitation, while the effect on the photorechargeability was small. Further research with high external excitation is in progress.