Fabrication And Photocatalytic Application Of The Novel Functionalized TiO₂Nanotube Arrays

Nanotechnology is known as one of the most promising new technology in the21st century. Photocatalytic activity is a very unique performance of the semiconductor nanomaterials, which has aroused great attention in scientific and technological fields. With the deepening of the global environmental awareness, photocatalytic technology to eliminate organic pollutants has caused extensive concern. Because of the high activity, large surface area, stable chemical properties and nontoxicity, TiO2nanotube arrays prepared by anodization are considered to be one of the most prospective green environmental photocatalyst.However, TiO2is a high band gap (3.2eV) and low conductivity semiconductor material, which makes the photogenerated charge carriers cannot be delivered effectively during the photocatalytic process and then affect the photocatalytic degradation rate. In order to solve the above problem, it is necessary to dope or modify the TiO2nanotube arrays, broadening its absorption scope in the visible range and prolonging the lifetime of photo-carriers.In this study, the principal line is from functionalization TiO2nanotubes array to environmental applications, the research focus is the improvement of photocatalytic activity, and the objective is the elimination of organic pollutants and heavy metal ions. We prepared PbS/TiO2、 CU2O/TiO2and Au/TiO2composite materials successfully and studied the photocatalytic application. The details are listed as follows:(1)Fabrication and photocatalytic application of PbS/TiO2nanocomposites. The anodic TiO2nanotube arrays with100nm pore size,4μm length were loaded with PbS by pluse electrodeposition. Then, we did the photocatalytic degradation of methyl orange under different experimental conditions. The results showed that:PbS was successfully coupled to the nanotube arrays, the incorporation of PbS had no effect to the morphology of TiO2nanotube arrays, but significantly increased the photocatalytic activity.(2) Fabrication and photocatalytic application of Cu2O/TiO2network composite. Firstly, Cu particles were loaded TiO2nanotube arrays by pluse electrodeposition. After that, the Cu/TiO2nanotube arrays were anodized in alkaline media, resulting in the ultra-fine Cu2O nanonetworks modified TiO2NTs. The investigation shows that The Cu2O/TiO2network has much higher degradation rate (1.97ug/min cm2) than the unmodified TiO2nanotube arrays (0.85μg/min cm2), p-nitrophenol which is a difficultly-decomposed organic pollutant under solar light in the absence of strong oxidants can be effectively degraded under artificial solar light when using the composite.The enhanced photocatalytic acitivity can be attributed to the extended absorption in the visible resulting from the Cu2O nanowire networks, and the effective separation of photogenerated carriers driven by the photoinduced potential difference generated at the Cu2O/TiO2p-n junction interface.(3) Simultaneous detoxification of hexavalent chromium and acid orange7by Au/TiO2heterojunction composite nanotube arrays with "tube-in-tube" construction.Gold nanotubes embedded within the pores of the anodic TiO2nanotube arrays were fabricated by a simple pulse electrodeposition technique, constructing a novel material with a unique Au/TiO2heterojunction. Under illumination, the electric potential difference generated on the interface of Au/TiO2heterojunction facilitated the separation of the photogenerated hole-electron pairs, accelerating the transferring rate of the electrons and resulting in an enhanced photocatalytic activity. In comparison with the single system, simultaneously enhanced photocatalytic degradation rate of acidic orange7(AO7) and reduction rate of Cr(VI) were observed due to the synergetic effect of Cr(VI)-AO7.