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

采用以tio_2固定透明导电氧化玻璃为电极的半导体电极，在紫外照射下，在氧气气氛下对苯磺酸盐、葡萄糖等水溶性有机物进行了光电降解。有机物通过氧化步骤矿化为CO_2气体。在这些过程中，形成乙酸和甲酸。通过电荷分离和羧酸的分解，光电流按“光电流倍增”的规律流向外电路。测定了在磁性NaCl电解液中产生的光电流对光降解速率和CO_2析出的影响。结果表明，光电电流的增加与衬底在TiO_2/TCO表面的吸附密切相关。揭示TiO_2薄膜的光催化和电化学特性具有重要意义。制备TiO_2/TCO薄膜电极的方法有：(1)脉冲激光CO_2沉积法，(2)溶胶-凝胶法，(3)粘贴法和溶胶-凝胶法相结合的混合方法。在球形反应器中对TiCl_4、H_2和O_2气体混合物进行激光闪击穿，在TCO板上沉积TiO_2薄膜。采用脉冲激光技术可以制备纯锐钛矿和均匀TiO_2薄膜。锐钛矿和金红石的结晶率取决于TiCl_4、H_2和O_2的气体组成。当H_2与O_2的比例为1:1时，可制得锐钛矿结晶率大于98%、薄膜宽度为0.4μm的薄膜。以该锐钛矿TCO/TiO_2为工作电极，Pt板为反电极，苯磺酸盐降解后产生的最大光电流为3 mA/cm^2。讨论了一种新型湿式太阳能电池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.