Au@TiO_2纳米管阵列的制备及光催化性能

Preparation and photocatalytic properties of Au@TiO_2 nanotube arrays

利用一种简单易行、可控的方法制备了均匀的Au@TiO_2纳米管阵列。首先在室温下通过阳极氧化的方法形成TiO_2纳米管,再在氧化后的TiO_2纳米管上用磁控溅射沉积不同厚度的Au膜,最后将沉积Au膜后的TiO_2纳米管在空气中450℃退火2h。热处理过程导致了Au向TiO_2纳米管的扩散,在纳米管表面形成了Au"岛"包裹的Au@TiO_2纳米管。对制备的Au@TiO_2纳米管的微观结构利用了扫描电子显微镜、能谱、X射线衍射和透射电子显微镜进行表征。并且用光电流、紫外可见光光漫反射光谱、荧光光谱和降解亚甲基蓝溶液的方法分析测量了Au@TiO_2纳米管的光电性能及光催化性能。结果表明:当可见光照射含Au@TiO_2纳米管催化剂的亚甲基蓝水溶液时,其光催化性能远远高于纯TiO_2纳米管,这是由于Au颗粒表面等离子体共振效应(LSPR)增加了电子-空穴对的分离并且延缓了其重组所致。

A simple, feasible and controllable method is presented to prepare uniform Au@TiO2 nanotube arrays by depositing Au nanofilms on the top of the TiO2 nanotube arrays via magnetron sputtering. The TiO2 nanotube arrays is obtained using the anodization process at room temperature, followed by heat treatment at 450℃ in air for 2h. The heat treatment leads to the migration of Au atoms into TiO2 nanotube arrays, resulting in the formation of the Au nanocrystals on the outer surface of the TiO2, i.e. the Au@TiO2 nanotube arrays. The microstructure of the prepared Au@TiO2 nanotube arrays is characterized by using scanning electron microscopy, energy dispersive spectrometer, X-ray diffraction and transmission electron microscopy. Also, the emporal evolution of photocurrent response, photoluminescence emission spectrum, UV-vis diffuse reflection spectra and photodegration of the methylene blue are used to evaluate its photoelectric and photocatalytic properties. Compared with pure TiO2 nanotube arrays, the Au@TiO2 nanotube arrays catalysts have much higher photocatalytic activity in the aqueous methylene blue solution under visible light irradiation. Such behavior can be contributed to the enhanced electro-hole separation and the reduced recombination of them through the localized surface plasmon resonance (LSPR) of Au nanoparticles.