Research On Cr, Mn, Co Ion Doping And ZnO Modified Titanium Dioxide

In recent years,titanium dioxide has been developed on a large scale and been used more and more widely in commerce.It is a common metal oxide,which will exist in a large number in nature.This leads to its low cost and easy access.At the same time,titanium dioxide has good chemical stability and photoelectric properties,which makes it non-toxic,harmless and environmentally friendly green material.The preparation methods of titanium dioxide nanotube arrays and their respective characteristics are as follows:titanium dioxide prepared by hydrothermal method or sol gel method usually has a relatively random growth direction,and the template method is limited due to the complex preparation process.Anodic oxidation method is not only easy to fabricate and produce highly ordered and oriented titanium dioxide nanotube arrays,but also has the advantages of small size,large specific surface area and one-dimensional tubular structure conducive to electronic transmission.In order to further improve and broaden its practicability,the purpose of this paper is to improve the two major shortcomings of titanium dioxide itself.Firstly,the band gap is too wide for titanium dioxide to effectively utilize visible light because of its limitation on light induction.Secondly,even under the irradiation of ultraviolet light,the number of photogenerated electrons will be limited and the formation of active species will be inhibited to some extent.To solve the first problem,in this paper,doping titanium dioxide with metal ions was selected.For the second problem,ZnO was chose to compound the nanotube arrays to form heterojunctions,which decrease the probability of photoinduced electron hole recombination and made the electrons diffuse to the surface of titanium dioxide.Based on the technology of low-temperature crystallization,the principle and characteristics of dissolution-crystallization of anodized titanium dioxide nanotube arrays were studied in the complex environment of transition metal ions aqueous solution,and an efficient method of low-temperature in-situ doping was developed.The influence of metal ions on visible-light photocatalytic activity was revealed,and titanium dioxide nanotube arrays were obtained with visible-light photocatalytic activity.At the same time,the formation mechanism of ZnO@TiO₂ heterojunction was studied,the specific effect of catalyzing macromolecular organic compounds was explored,and compared with pure titanium dioxide nanotube arrays,the effects of different composite methods on catalytic performance were studied,and the preparation scheme was proposed to obtain heterojunction films with the best catalytic performan.