Deposition of Copper Indium Sulfide on TiO2 Nanotube Arrays for the Photocatalytic Degradation of IPA in Air Streams

• Main Authors: Pei-yu Lin, 林佩玉
• Other Authors: Young Ku
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/wtmvv7

碩士 === 國立臺灣科技大學 === 化學工程系 === 100 === TiO2 nanotube arrays were fabricated in ethylene glycol containing NH4F and water by anodization process under various conditions. TiO2 nanotube arrays were analyzed by field-emission scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction spectra, Potentiostat/Galvanostat, and photoluminescence spectroscopy in order to investigate characterization of TiO2 nanotube arrays. Effects of electrolyte temperature and water content of electrolyte on morphology and formation mechanism of TiO2 nanotube arrays were investigated. The experiment results demonstrate that TiO2 nanotube arrays with longer lengths, larger inner diameters, and thinner wall thicknesses could be fabricated in electrolytes of higher temperature, indicating that the limiting factor for growth of TiO2 nanotube arrays is the diffusion of reactants (oxygen-containing anionic species, fluorine ions) into the tubes or products ( [TiF6]2- ) away from the tubes. The experiment results also suggest that the appearance of “hazy layer” on the top of TiO2 nanotube arrays could be avoided by anodizing at lower temperatures. With the presence of higher water contents, the relatively fast chemical dissolution rate dominates the reaction because a larger amount of H+ ions are created, resulting in TiO2 nanotube arrays with larger inner diameters and shorter tube lengths. Strctures (tube length and inner diameter) of TiO2 nanotube arrays were controlled by adjusting anodization time and water content in anodization process. The experimental results show that experiments using TiO2 nanotube arrays with longer tube lengths and smaller inner diameters achieved higher photocatalytic performance. However, the photocatalytic activity of TiO2 nanotube arrays is after all limited by the penetration of illumination. From the PL analysis results of the prepared TiO2 nanotube arrays, bulk recombination is expected to be reduced as wall thickness become thinner, and the photoconversion efficiency is also expected to be enhanced. TiO2 nanotube arrays were modified with copper indium sulfide by successive ionic layer adsorption and reaction (SILAR) method. The modified TiO2 nanotube arrays were mainly analyzed by X-ray photoelectron spectroscopy and Potentiostat/Galvanostat to investigate their characterization. In the study, the XPS analysis results demonstrate the presence of copper indium sulfide thin film could only be observed on TiO2 nanotube arrays before the modified TiO2 nanotube arrays were annealed. TiO2 nanotube arrays were modified with copper indium sulfide by SILAR method resulting in some deviation on the molecularity and stoichiometry of copper indium sulfide, which affects the electrical property of the modified TiO2 nanotube arrays. Typically, In-rich copper indium sulfide thin films could be obtained by using lower sulfur precursor concentrations in SILAR method and the deposited films belonged to n-type semiconductor; the p-type Cu-rich copper indium sulfide thin films could be prepared by using higher sulfur precursor concentrations in SILAR method. When the chemical composition of Cu, In, and S is closer to the stoichiometric composition of copper indium sulfide (1:1:2), the modified TiO2 nanotube arrays exhibit higher photocatalytic performance for degrading gaseous IPA. Moreover, the modified TiO2 nanotube arrays show excellent stability during the photocatalytic process.