Investigation on the photodegradation of organic contaminants by a semiconductor thin film electrod

采用二氧化钛固定透明导电氧化物玻璃的半导体电极，在氧气气氛中紫外光照射下对苯磺酸盐、葡萄糖等水溶性有机物进行光降解。有机质通过氧化步骤被矿化为CO2气体。在这些过程中，形成了醋酸和甲酸。通过电荷分离和羧酸的分解，光电流根据光电流倍增流向外电路，测量了在无烟的氯化钠电解液中光降解速率和CO_2释放的光电流产生。外加偏压使光电流增大，这与衬底在TiO2TCO表面的吸附密切相关。揭示二氧化钛薄膜的光催化和电化学性质具有十分重要的意义。采用脉冲激光CO_2沉积法、溶胶凝胶法、粘贴和溶胶凝胶法相结合的方法制备了纳米二氧化钛/二氧化钛薄膜电极。特别是在球形反应器中对TiCl4、H2和O2的混合气体进行了激光闪光击穿，在TCO板上沉积了TiO2薄膜。利用脉冲激光技术可以制备出纯净、均匀的锐钛矿型二氧化钛薄膜。锐钛矿和金红石的结晶率取决于TiCl4、H2和O2的气体组成。当H2和O2的组成为1：1时，可制得锐钛矿晶率大于98%、薄膜宽度为0.4μm的薄膜。以锐钛矿型TCO/TiO2为工作电极，以铂片为对电极，降解苯磺酸盐产生的最大光电流为3 mA/cm2。讨论了在太阳光照射下产生光电流的可能性。

Water-soluble organics such as benzene sulfonate, glucose, etc. were potodegraded in oxygen atmosphere under UV-illumination using a semicondtuctor electrode of which TiO_2-fixed transparent conductive oxide glass was employed. The organics were mineralized to CO_2 gas via oxidation steps. During these processes, acetic and formic acids were formed. The photocurrent was flowed to an outer circuit according to the "photocurrent doubling" by the charge separation as well as the decomposition of carboxylic acids.The photocurrent generation for the photodegradation rate and CO_2 evolution was measured in agneous NaCl electrolyte. The increase of photocurrent by applied biases was examined, which was closely related to the adsorption of the substrates on TiO_2/TCO surface. It is very important to reveal the photocatalytic and electrochemical characteristics of TiO_2 thin films. The TiO_2/TCO thin film electrode was prepared by the following procedures : (1) pulse-laser CO_2 deposition method, (2) sol-gel mnethod, (3) hybrid method combined with pasted and sol-gel techniques. In particular, the laser flash breakdown for the gas mixture of TiCl_4, H_2 and O_2 in a globular reactor was carried out to deposit TiO_2 thin film on TCO plate. The pure anatase and homogenous thin film of TiO_2 can be prepared by the pulse laser technique. The crystalline ratio of anatase and rutile is dependent upon the gas composition of TiCl_4, H_2 and O_2. When the composition of H_2 and O_2 was 1 : 1, the fine thin film having anatase crystal more than 98% and thin film width of 0.4μm was manufactured. When this anatase TCO/TiO_2 was employed as a working electrode with Pt plate as a counter electrode, benzene sulfonte was degraded to generate the maximum photocurrent of 3 mA/cm^2. The possibility of a newly wet solar cell was discussed concerning the photocurrent generation under solar exposure in the photodegradatin of aquatic pollutants.