| Environmental pollution is increasingly serious as the rapid development of human society. Chemical Oxygen Demand(COD) is an important index for water quality detection. Existing methods include potassium permanganate and potassium dichromate method, which oxide organic pollutants in water and then titrate remaining oxidant substances to calculate COD. Both of them need long time and cost are expensive. So develop sensitive and rapid analysis of COD method has important practical value.The main purpose of this paper is to construct Ti supported TiO2 nanotube array electrode, prepared TiO2 nanotube by anodic oxidation method, regulate the microstructure of the nanotube by changing the parameters of experiment. And then discussed the relationship between film nanostructure morphology and its performance in this article, and studied nanostructures photocatalytic electrode application in chemical oxygen demand detection. At last, Pt nanocrystalline were doped on the surface of TiO2 nanotube by galvanostatic deposition method and titanium wire supported Pt/TiO2 nanotube array electrode was prepared, and this electrode can be used for rapid electrocatalytic detection of COD in water. Main contents include:(1) Ti supported TiO2 nanotube array was prepared by using anodic oxidation method. Choose two kinds of electrolytic liquid systems to prepare TiO2 nanotube: NH4F-ethylene glycol system and HF-ethylene glycol system. These two systems can prepare TiO2 nanotube arrays successfully, however, HF has higher corrosiveness than NH4 F, it is suitable for preparing large-size nanotubes. In NH4F-glycol system, set oxidation voltage from 20 V, 30 V and 40 V respectively, and oxidation time is one hour, TiO2 nanotube arrays are all dense. Among them, TiO2 nanotube with 30 V oxidation voltage has the best form of morphology. In HF-glycol system, oxidation voltage and time remain the same, the prepared nanotubes array were longer and finer, arrangement is more dense as well. Further photoelectric chemical test showed that: TiO2 nanotube with oxidation voltage 30 V in NH4F- ethylene glycol system had the best photocurrent response.(2) In order to increase the photocatalytic activity, TiCl4 solution and liquid deposition method were used to modify TiO2 nanotube array. TiCl4 post-processing methods is widely used in dye sensitized solar cell. In TiCl4 post-processing method, TiO2 nanoparticles were deposited on the nanotube surface. On the one hand, nanoparticles can increase ultraviolet light absorption and improve the utilization rate of electrode, on the other hand, rough surface of the nanotubes can adsorb more organic substances in water, thus improve the rate of degradation. The experimental results showed that: nanotube electrode hydrolysis of 30 min has the best photocurrent corresponding. Photocurrent increased 19%. In liquid phase deposition method, TiO2 nanotube were dipped in(NH4)2TiF6 and H3BO3 solution, deposition rate is very fast nanoparticles deposited on the nanotube surface. Compared with the TiCl4 post-processing, deposit speed is very fast when heating, a thin film was formed on the nanotube surface in 30 min. With the increase of deposition time, TiO2 thin films became thicker and thicker. chose the best photocatalytic performance electrode as a test sample, selected five kinds of organic matters including glucose, made a series of concentrations of organic matter in sodium nitrate solution, test the TiO2 nanotubes photocurrent response curves for different concentrations of organic matter, thus it is concluded linear relationship between the static current and concentration of organic matter. Detection limit is 1.5 mM.(3) Electric catalytic oxidation method is called as a "environmentally friendly" technology, it has incomparable superiority like mild reaction condition, high energy efficiency, can be used under the atmospheric pressure, equipment and the operation is simple, small occupation area, low cost and produces little or no secondary pollution and so on. By far, TiO2 is the most widely used and ideal photoelectric catalyst, TiO2 does not dissolve in water and leak In the process of electric catalytic, This test chose the nano TiO2 in catalysis research, TiO2 is a kind of high corrosion resistance of the substrate electrode materials, the high catalytic activity of metal Pt particles with nanometer TiO2 membrane catalytic activity can be obtained high, stable performance of the new electric catalyst, this paper chose to Pt/TiO2 composite structure to electric catalytic oxidation of methanol test, in addition. This chapter also studies the Pt composite electrode for organic matter detection, selected different organisms, found under the condition of electrocatalysis, Pt composite catalyst can catalytic degradation of organic matter. |
PDF Full Text Request