The Preparation And Photocatalytic Property Of Modified TiO₂ Nanocrystals With Broad Spectrum

With the quick development of human community, the environment pollution problem has become one of the key problems to threat the sustainable development in modern society. Semiconductor photocatalytic technology can not only degrade the environmental pollutants efficiently, its application in the territory of renewable energy can remit press of fossil fuels and avoid environmental pollution from the burning of fossil fuels. Thus photocatalytic technology has great signification for dealing with environmental pollution and energy crisis and achieve sustainable development. Nanometer TiO2 photocatalyst is one of the most widespread use photocatalyst because of its stability, inexpensive price and non-toxic.But TiO2 is large energy gap semiconductor, which can only absorb ultraviolet which accounted for about 5% of sunlight merely. This leads to the low utilization of sunlight. Besides, recombination of carriers is also one of the main retarding factors to improve the performance of TiO2 photocatalys. So how to expand the TiO2 light response region, and inhibit carrier recombination have been the most dramatic issue and the direction. In this paper, nanometer TiO2, BiaWO6/TiO2 ceramic matrix composite and N,Fe-Bi2WO6/TiO2which have certain feature and structure are compounded by changing reaction conditions and auxiliary agent type. The effects of experimental conditions on its microstructure and its preparation mechanism, and the photometric characteristics and photocatalytic performance were studied. The concrete research content is as follows:1. TiO2 nanotube arraysTiO2 nanotube arrays are synthesised in the ethylene glycol solution of NH4F by electrochemical constant voltage anodic oxidation method.The effect on the TiO2 nanotube arrays of voltage, time, electrolyte constituent were studied. The results indicate that the diameter and length of the nanotubes increase when the voltage enlarge. When the voltage come to 60V, TiO2nanotubeshave ruptured,and nanowires can be observed. When the voltage is increased to 80V, a large number of nanowires can be seen on the surface of TiO2 nanotube arrays. Ultraviolet-visible diffuse reflection spectrum showed that TiO2 nanotube arrays have good absorption in the UV area. Current density-oxidation time chart shows that anodic oxidation process is separated into three stages, and germinate of nanotubes under high voltage condition is not stable.2. Synthesis of N, Fe doping TiO2 nanotubes and TiO2 nanotube arrays and their photochemical catalysis performanceTiO2 nanotubes are synthesised by hydrothermal method, TiO2 nanotube arrays and TiO2 nanotubes are doped by impregnation method. Fe and N doping TiO2 have higher absorption in visible light area. Methyl orange is degraded by different doping type TiO2 nanotubes and the TiO2 nanotube arrays in the sunlight. The result indicated that, after 160min, the degeneration efficiency to methyl orange of TiO2, Fe-TiO2, N-TiO2 and Fe, N-TiO2 nanotube arrays is 32.60%, 50.41%,53.29%,62.80%,respectively. After 180min, the methyl orange degeneration efficiency of TiO2, Fe-TiO2, N-TiO2 and Fe, N-TiO2 nanotubes is 38.6%,52.21%,65.44%,66.82%, respectively. After doping Fe, N, TiO2 have better photochemical catalysis performance.3. The preparation and photocatalytic properties of wide spectrum absorb TiO2 nanotube arraysThe TiO2 nanotube arrays are compound with anodic oxidation method, N and Fe were doped by impregnation method, then combined hydrothermal method to synthesis N, Fe-Bi2WO6/TiO2. The modified titanium dioxide photocatalyst shows wide spectrum range of light absorption and high photocatalytic efficiency. UV-vis-near infrared diffuse reflection spectrum showed that N, Fe-Bi2WO6/TiO2 has the strong absorption in the visible and near infrared region. N, Fe-Bi2WO6/TiO2 has a strong ability on the deprivation of MO, in the sun the deprivation of MO rate relative to the doping titanium dioxide nanotube arrays is increased by 171%. In sunlight, pharmaceutical wastewater COD removal rate compared with not doped TiO2 nanotube arrays from 45.6% to 61.1%. In xenonlamp light, pharmaceutical wastewater COD removal rate compared with not doped TiO2 nanotube arrays from 53.3% to 84.2%. The photocatalyst has the best photocatalytic performence. When the pH is 7.