Preparation Of Ag Loaded Titania Nanotube Arrays And Their Photocatalytic Performance

Nano-titanium dioxide (TiO2) is a kind of N-type semiconductor material, which has stable physical and chemical properties. Owing to some unique properties (such as optical, photosensitive, gassensitive and other characteristics), it is used for instance in the field of photocatalytic degradation of organic pollutants, sensors, solar cells, photovoltaic and many other applications. However, its many practical applications are limited by its wide-bandgap (the bandgap of anatase TiO2 is as wide as 3.2 eV). Therefore, intense efforts focus on modifying the electronic properties of TiO2 by band-gap engineering, doping it with some inorganic, organic, metallic or magnetic nanoparticles to further enhance the catalytic, magnetic and other aspects properties of TiO2 nanotubes.In this article, the fabrication and characterization of TiO2 nanotube arrays and Ag nanoparticles loaded TiO2 nanotube arrays, and their photochemical catalysis function of organic compounds were studied, which provided a theoretical basis for the preparation of the titanium dioxide as photocatalyst and their practical applications. The morphology, structure and composition of the as-prepared samples were characterized using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), UV-Visible absorption spectroscopy and other means. The photocatalytic properties of the formed samples were tested by testing the photocatalytic degradation effect of methyl orange and safranine T using double-beam UV-Vis spectrophotometer.The titania nanotube arrays were firstly prepared on the titanium foil via an electrochemical anodic oxidation method in this paper. The influences of the anodic oxidation parameters (cathode material, electrolyte type, electrolyte composition, oxidation voltage, time, temperature, etc.) on the morphology of TiO2 nanotube arrays were studied in detail. The results show that the length of the nanotubes is mainly influenced by supplied voltage and oxidation time, supplied voltage and the fluorine ion concentration in the electrolyte are the main factors affecting the pipe diameter, and the tube wall thickness is strongly influenced by fluorine ion concentration in the electrolyte and oxidation time.Using formaldehyde as a reducing agent, the silver ammonia complex ions were turned into Ag nanoparticles, and then loaded on the surface of titanium dioxide nanotubes, which will enhance the photocatalytic properties of TiO2 nanotube arrays. The orthogonal test was arranged with the concentration of silver ammonia solution, alternate immersion times and alternate immersion time of the samples in the formaldehyde and silver ammonia solution respectively as three factors. The optimization of Ag loaded nanotube arrays was obtained, in which loaded amount of the Ag nanoparticles is 0.87 at.%, and diameters of them are about 37.91 nm The range analysis indicate that the concentration of silver ammonia solution has the largest effect on the amount and diameter of the loaded Ag nanoparticles, and the alternate immersion time of the samples in the formaldehyde and silver ammonia solution is the least important factor to the results. XRD and XPS results indicate that valence state of the loaded Ag is Ag0. The results of photo-degradation effect of methyl orange and safranine T reveale that the Ag nanoparticles loaded TiO2 nanotube arrays have better photocatalytic performance than pure TiO2 nanotube arrays.