Modification And Photocatalytic Performance Of TiO₂ Nanotube Arrays

Water environmental protection and its sustainable use are important guarantees for sustainable economic and social development.However,water pollution is time–consuming due to large range,more pollution sources and stable pollutants.Photocatalytic technology is widely used for water pollution treatment due to its low cost and environmental friendly.TiO₂ is one of the most promising photocatalysts due to it's non–toxicity,low cost and high stability.However,it has lower photocatalytic activity and higher photogenerated electron–hole recombination due to the large band gap?Eg=3.0 to 3.2 eV?.In order to improve the photocatalytic performance of TiO₂,Fe₂O₃ and Ti³⁺were used to narrow the band gap of TiO₂ nanotube arrays and reduce the photogenerated electron–hole recombination rate in this paper.The main contents are as follows:?1?TiO₂ nanotube arrays located with Fe₂O₃:TiO₂ nanotube arrays?TiO₂NTs?were first prepared by anodization using a titanium wire as the substrate.Then,Fe₂O₃supported on TiO₂ nanotube arrays?Fe₂O₃/TiO₂NTs?were prepared by combining electrochemical deposition and anodic oxidation processes,and the effects of different Fe₂O₃ loads on the properties of TiO₂ nanotube arrays were further investigated.X–ray photoelectron spectroscopy?XPS?results showed that the binding energy of Ti–O bond of Fe₂O₃/TiO₂NTs decreased.Photocurrent and diffuse reflectance results showed that Fe₂O₃/TiO₂NTs had faster carriers mobility and stronger visible light absorption than TiO₂NTs.The photocatalytic activity of Fe₂O₃/TiO₂NTs was higher than that of TiO₂NTs.The degradation extent of p–nitrophenol was over 45%than that of TiO₂NTs.The degradation extent of p–nitrophenol was only reduced by 2.9%after 5 cycles using Fe₂O₃/TiO₂NTs.In addition,the byproducts and degradation pathways of p–nitrophenol were also analyzed by HPLC.The main significance of this work is to controllably prepare a highly efficient and stable photocatalyst by fast and green electrochemical method,which provides a new idea for designing high–efficiency supported TiO₂–based photocatalysts.?2?Ti³⁺self–doped TiO₂ nanotube arrays:TiO₂ nanotube arrays?TNTs?were prepared by anodization using titanium mesh as the substrate.Then,Ti³⁺self–doped TiO₂ nanotube arrays?TNTs?X?,X was the reduction voltage?were prepared by cathodic reduction process.The properties of TNTs?X?prepared under different reduction voltages were investigated.XPS results showed that the Ti³⁺concentration increased as the reduction voltage increases.Diffuse reflection results showed that the visible light absorption performance of TiO₂ was enhanced after Ti³⁺doping,and the band gap is obviously reduced by the introduction of impurity level.Transient fluorescence results indicated that the lifetime of photogenerated electrons was prolonged after the induction of Ti³⁺.The photocatalytic degradation of chloramphenicol showed that the photocatalytic activity of TNTs?X?was higher than that of P25 and TNTs,and the degradation extent of chloramphenicol was 1.6 times that of P25 and over 21.9%than that of TNTs.The degradation extent of chloramphenicol was only reduced by 3%after 5 cycles.In addition,the byproducts anddegradationpathwayofchloramphenicolwereanalyzedbyliquid chromatography–mass spectrometry?HLPC–MS?.The main significance of this work lies in the preparation of Ti³⁺self–doped TiO₂ nanotube arrays by simple electrochemical reduction process,which has high photocatalytic activity and stable performance,providing an ingenious idea for the development of self–doped catalysts.