Study On Preparations And Photocatalytic Properties Of The Colored Titanium Dioxide

The photo-catalytic technology rose in 1970s. After developed three or four decade years, the basic theory of the photo-catalytic technology and the photo-catalytic effect is gradually improved. Which is expected to solve the current environmental pollution and energy crisis what are the two major world problems.Titanium dioxide is the most common semiconductor material in photo-catalytic technology. As its excellent photo-catalytic performance has been attracted enormous attentions from different researchers from all over the world. After developed so many years, the researchers have done a lot of research on morphology and photo-catalytic modification of titanium dioxide. In recent years, there is a method of preparation of black titanium dioxide. This preparation method of black titanium dioxide, not only can effectively promote the separation of electrons and holes, but also improve the photo-catalytic degradation of pollutants. And it can significantly reduce the band gap of titanium dioxide. What is more ,the traditional titanium dioxide response from the UV light gradually move to the visible light, the absorption of sunlight reached 85%.The method can solve the problem that the titanium dioxide only respond to ultraviolet light and the high combination of electrons and holes.This method of black titanium dioxide materials preparation are widely used in solar power, photo-degradation of water, super-capacitors and pollutants degradation and medical research.In this paper, we study the relatively mild method of colored titanium dioxide preparation. This method reduces the reaction temperature of the original preparation method from the original 800? to the experiment 250?-350?. So this method has a significant energy saving effect and shorten the reaction time. We used the industrial P25 as the raw material for the preparation of colored titanium dioxide, by controlling the addition amount of sodium borohydride, by controlling the reduction time and the temperature of the reduction reaction, we prepared colored titanium dioxide with different color gradient (blue - gray - gray black - black). Through the transmission electron microscopy, we found that the titanium dioxide has a core-shell structure (Ti02/TiO2-x), whose internal is the regular titanium dioxide crystal structure, the external is amorphous shell.Studies have shown that the control conditions are different, the thickness of the colored titanium dioxide shell is different, the appearance of the titanium dioxide color is not the same, corresponding to the different oxygen concentration of the shell. Because the concentration of oxygen vacancy has different effects on the photo-catalytic efficiency, the material exhibits different photo-catalytic properties. By comparing the photo-catalytic effects of the materials, we found that the reduction temperature, the amount of titanium dioxide and sodium borohydride and the reduction temperature had a significant effect on the photo-catalytic efficiency of the colored titanium dioxide. We found that when the reduction temperature was 250? the mass ratio of titanium dioxide and sodium borohydride was 4:1.5 and the reduction time was 1 hour, the blue titanium dioxide has the best photo-catalytic effects.Because the colored titanium dioxide shell has amorphous structure, with oxygen vacancy, which is easier than the traditional titanium dioxide with a crystalline structure to achieve doped non-metallic elements. Then we through the "one-step method" and "two-step method" to achieve the nitrogen dioxide doped titanium dioxide, titanium dioxide changing the bond from the original Ti-O-Ti bond into Ti-N-Ti bond, and the photo-catalytic degradation of toluene was studied. Studies have shown that this photo-catalyst has a very good photo-catalytic performance.