Chalcogenide Semiconductor/Graphene Hybrid Modified TiO₂Nanotube Arrays And Their Application

Over the past decade, because of its high regulation, large surface area, rapid recycling and excellent stability, highly ordered TiO2nanotube arrays prepared by anodic oxidation have attracted great attention on photocatalysis. However, the band gap of TiO2nanotube arrays is very wide (3.2eV for anatase), leading to its absorption only in UV light region. Otherwise, its high photo induced charge recombination and low quantum yield limit the applicability of TiO2nanotube arrays. The effort to promote its visible light photocatalytic activity is of great significance on its practical applications.In this thesis, TiO2nanotube arrays prepared by electrochemical anodic oxidation method were modified by CuInS2or CdTe/graphene composite. The resulting photocatalysts were evaluated by the photocatalytic degradation of2,4-dichlorophenyloxyacetic acid (2,4-D). The main studies are as follows:(1) Fabrication, characterization and photoelectrochemical properties of RGO/CuInS2-TiO2nanotube arrays:reduced graphene oxide (RGO) and CuInS2nanoparticles (NPs) co-decorated TiO2nanotube arrays (NTs)(RGO/CuInS2-TiO2NTs) as a photocatalyst prepared by successive pulse electrodeposition of CuInS2and RGO film onto the top surface of TiO2NTs. Compared with the unmodified TiO2nanotube arrays, RGO/CuInS2-TiO2nanotube arrays showed remarkablely increased visible light absorption, higher photocurrent. The new catalyst exhibits significant photocatalytic activity and good removal efficiency of2,4-D. The photodegradation rate toward2,4-D over RGO/CuInS2-TiO2NTs under simulated solar light irradiation is96.2%, much higher than68.0%over CuInS2-TiO2NTs,50.1%over RGO-TiO2NTs and36.0%over bare TiO2NTs, respectively, meaning that the photocatalytic performance of TiO2NTs could be greatly enhanced by the synergetic effect of RGO and CuInS2.(2) RGO/CdTe-TiO2nanotube array was prepared through one step pulse-electrodeposition and the morphology, crystal structure, photocatalytic performance were investigated. After180min photodegradation, the photocatalytic degradation efficiency of2,4-D over RGO/CdTe-TiO2nanotube arrays is84.1%, much higher than42%over CdTe-TiO2nanotube arrays and36%over the pure TiO2 nanotube array. The results show that the presence of graphene films can improve the photocatalytic properties.