| At present, photocatalytic technique is mainly used in developing new energy, like decomposing water into hydrogen and oxygen. Meanwhile, it also can be used to recycle the noble metals and decompose toxic substances such as organic pollutants, NOx, etc. in wastewater and air, In addition, the photocatalyst is used to degrade microorganism, bacterium, etc. into small molecules such as CO2 and H2O. This is why photocatalysis is known as "the bright and clean revolution".Among various currently studied photocatalysts, titanium oxide has gotten extensive attention due to its high chemical stability, excellent functionality, nontoxicity, and relatively low price. Although titanium oxide photocatalysis has been confirmed as one of the most potential environment treatment technologies, low photocatalytic activity and limited photoresponse region hinder its practical applications. Recently, doping has been attempted as a facile method to improve the the performance of TiO2.In order to fully utilize sunlight, researchers have devoted to develope visible-light activated photocatalysts and have made certain progress. For example, surface modification and doping can make TiO2 response to the visible light. However, there is very few photocatalyst that can decompose toxic pollutants efficiently at present. Hence developing photocatalysts that is sensitive to visible light has become a hot topic.In this dissertation, a series of visible-light-driven photocatalysts have been synthesized, and these photocatalysts were expected to show an enhancement in photodegradation efficiency under visible light.1. C-N-codoped titanium dioxide was prepared by solid-state method. The codoping powder was characterized by X-ray diffraction (XRD), UV-vis adsorption spectroscopy (UV-vis), XPS measurement and Raman spectroscopy. The effect of doping species and amounts, calcinations temperature on the photodegradation efficiency was investigated. It is proved that the light-yellow C-N-codoped titanium dioxide prepared under molar ratio of P25:urea=1:8 and the calcinations temperature of 500℃showed the best photocatalytic activity owing to the synergetic effect of carbon and nitrogen atoms.2. Ti-doped Bi2O3 was prepared using hydrothermal approach and employed as photocatalyst. The relationship between its structure and photocatalytic activity, as well as it structure stability during the photocatalytic reactions were investigated and analyzed. Photocatalytic evaluation results show that 20 mg/L Indigo carmine solution became colorless quickly, which is attributed to Ti-dopedβ-Bi2O3 exhibiting strong adsorptive capacities and photocatalytic efficiency to the indigo carmine molecules. Meantime, Ti-dopedβ-Bi2O3 showed high photocatalytic activities in degrading rhodamine B and methylene blue. This highly photocatalytic performance may be associated with the extra structural distortion and additional optical absorption because of titanium atoms'doping.3. ZnBi2O6 and MgBi2O6 were prepared by hydrothermal technique. These two photocatalysts showed intensive absorption under visible light. This is why they have outstanding performance in degrading various pollutants like indigo carmine, rhodamine B, methylene blue and methylene orange. Meanwhile, they are stable in photocatalytic reaction process. This is due to their structure of stable (Bi2O2)2+...
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