Studies On Photoelectric Properties Of Surface And Interface About Titanate Sodium Nanotubes And Correlated Nanocomposite System

One-dimensional(1D) nanostructured TiO2 materials such as nanotubules,nanowires have gained considerable attention for their brilliant prospects in photocalalyst,environment purification,solar cell and gas and humidity sensor. Especially from Kasuga and his coworkers developed a simple method of hydrothermal systhesis and obtained TiO2 nanotube in 1998, researchers devoted more and more attention to this material. Among these reseaches, however, the efforts focus on the compositions,structure and formation mechanism,only little attention have been paid to the properties of these 1D nanostructured materials. In fact, the eledtronic properties play a key role in determining their photo/eledctronic performance.The SPV method is a well-established contactless and nondestructive technique for semiconductor characterization that relies on analysizing illumination-induced changes in the surface voltage. SPS is an effective tool to investigate the photophysics of excited states generated by absorption in the aggregate state. SPV measurement features many advantages. In addition, SPS is a kind of action spectrum. The information provided by SPS is about the properties of sample surface layer (several atomic layers). This technique has been successfully employerd for the study of the charge transfer in photostimulated surface interation,dye sensitization processes and phtocalalysis.On the basis of the principle of SPS, the following is my work which is made of three parts: In Chapter 2, we modified titanate sodium nanotubes with CdSe quantum dots(QDS) by using bifunctional surface modifiers(HOOC-SH). The properties of these functional material were characterized by TEM,XRD,FTIR and so on.In Chapter 3, we characterized the photo/eledctronic properties of titanate sodium nanotubes modified by CdSe QDS by using SPS,FISPS,PL,UV-vis absorption. The results indicated that the titanate sodium nanotubes have higher and wider photovoltage response in the longer wavelength regions after modified with CdSe QDS than before. And their FISPS were also different. The indensity of photovoltage of titanate sodium nanotubes increased with the enhancement of the positive electric field, and decreased with the enhancement of the negative electric field. However, the indensity of photovoltage of the functional material first increased with the enhancement of the positive electric field, when the intensity of the electric field reached a certain value, the indensity of photovoltage increased in some wavelength regions while decreased in other wavelength regions. We invesitigated and analyzed this phenomena in details.In Chapter 4, we prepared titanate sodium nanotubes by hydrothermal method and studied the influence of annealed temperature on the photo/eledctronic properties of this material. The results indicated that, when the temperature under 300℃, the peak position of the spectroscopy was immobile while the response threshold value was red shift as the tempreture increased. But when the temperature over 300℃, both of the peak position and the response threshold value were blue shift as the annealed temperature increased. Under electric field, all the response threshold values of all the treated samples under different temperature extended to longer wavelength.