Preparation And Photocatalytic Activity Research Of Silver Phosphate Series Compound Photocatalytic Material

In the year of 2010, Ye et al research group discovered the new-type semiconductor Ag₃PO₄ photocatalytic material, it can absorb the sunlight smaller than530 nm, and has stronger oxidizing ability, so it has attracted wide attractions of the researchers in aspects of photosplitting water and degrade pollutants. However, the silver phosphate material is easily photo-corred, which is greatly reduced its stability in the photocatalytic progress. Recently, the researchers discovered that the Ag₃PO₄-matrixed photocatalytic could effectively degrade the organic pollutants and maintained excellent stability. It has successfully solved the above shortcomings of Ag₃PO₄ and could greatly improve its photocatalytic activity. Hence, in this thesis, for the new-type visible light-response Ag₃PO₄ photocatalyst, the four kinds of compound visible light-response photocatalytic material, such as Ag₃PO₄/Ag, Ag/Ag₃PO₄/BiPO₄,Ag₃PO₄/CeO2 and FeOOH/Ag₃PO₄ were successfully prepared in order to effectively improve the photocatalytic activity and stability of the single material, The relationship of microstructure, energy-band structure and photocatalytic activity was explored its reaction mechanism. The main research contents of this thesis are as follows:1. The Ag₃PO₄/Ag photocatalytic material was successfully prepared by the one-step low-temperature oil bath method. The UV-vis diffuse reflectance analysis manifests that the Ag₃PO₄/Ag compound photocatalytic material has better light absorbing performance than the single Ag₃PO₄ material under the visible light conditions. The degradation experiment for the Rhodamine B under the visible light manifests that the activity of this material is obviously higher than the single Ag₃PO₄,and within 90 minutes, almost completely degradation for Rhodamine B. Besides, it has researched the influences of different dye properties（RhB,MB,MO） on photocatalytic performances. And the results manifest that: the cationic dye（RhB,MB） has better photocatalytic degradation effects than the anionic dye does, and this is mainly caused by the he charging characteristics on the surface of the preparedAg₃PO₄/Ag compound photocatalytic material. The reason why the Ag₃PO₄/Ag compound photocatalytic material has excellent activity is mainly because of the surface plasmon effects of Ag particles and the large amount of negative charges of PO₄3-ions.2. The Ag/Ag₃PO₄/BiPO₄ double-heterostructured nanocomposites was synthesized by a one-step low temperature chemical bath method. The experiment results manifest that the obtained material is Ag/Ag₃PO₄/BiPO₄; The HRTEM result shows that the Ag/Ag₃PO₄ and Ag₃PO₄/BiPO₄ heterostructures are formed. The Heterogeneous Ag/Ag₃PO₄/BiPO₄ photocatalyst exhibited better photocatalytic activity and better stability than those of individual Ag₃PO₄ an BiPO₄ nanoparticles for photodegradation of organic compounds（Rhodamine B） under visible light irradiation. The excellent photocatalytic performance of Ag/Ag₃PO₄/BiPO₄ photocatalyst is attributed to the formation of effective heterostructures as well as the existence of Schottky protential barrier, which can effectively improve the separation efficiency of electron and holes of Ag₃PO₄ material.3. The composite Ag₃PO₄/CeO2 photocatalyst, a novel p-n type heterojunction, has been successfully fabricated through a facile hydrothermal process combined with a successive in situ precipitation technique. Make use of the characterization methods such as XRD,SEM,HRTEM and UV-Vis to analyze the Ag₃PO₄/CeO2 compound photocatalytic material. The SEM and TEM image show that CeO2 particles have been successfully loaded and well distributed in the surface of Ag₃PO₄. The UV-vis diffuse reflectance analysis shows that the Ag₃PO₄/CeO2 compound photocatalytic material has better light absorbing performance than the single Ag₃PO₄ and CeO2 material under the visible light conditions. The enhanced photocatalytic activity can be attributed to the extended absorption in the visible light region resulting from the Ag₃PO₄ and the effective separation of photogenerated carriers driven by the internal electrostatic field in the junction region.4. The composite α-FeOOH nanorods/Ag₃PO₄ photocatalyst has been successfully fabricated through a facile hydrothermal process combined with a successive in situ precipitation technique. And make use of the characterization methods such as XRD,SEM,HRTEM and UV-Vis to perform the characterization on the α-FeOOH/Ag₃PO₄ compound photocatalytic material. The SEM and TEM image show that Ag₃PO₄ particles have been successfully loaded on the surface of FeOOH nanorods. Under the visible light effects, the experiment of α-FeOOH/Ag₃PO₄ photocatalytic material toRhodamine B manifests that the activity of this phstocatalyzer is obviously higher than the single Ag₃PO₄ and α-FeOOH nanorods. Through the research on the photocatalytic reaction mechanism, its excellent photocatalytic activity mainly depends on the photo-electronics caused by the energy-band matching of them as well as the effective separation of the electron holes. Besides, the photocatalytic results manifest that α-FeOOH/Ag₃PO₄ compound photocatalytic material has better photochemical stability than the single Ag₃PO₄ material.