Preparation,Characterization,Photocatalytic Degradation Of Dye Solution And Photocatalytic Mechanism Of Tungstate Semiconductor Composite Photocatalysts

People are engjoying the benefits from technology when they are suffering from various troubles. A massive amount of rivers and lakes have been polluted while coal and petroleum and other non-renewable resource drying up quickly. These energy and environment problems have seriously affected the production and live of people. Semicoductor as a new material has been widely attended for it can store solar energy and decompose organic pollutants. Now the study of semiconductor photocatalysts is foucus on the design of synthesis, the performance improvement as well as its potential catalytic mechanism. In this paper, Ag nanoparticles dopped ZnWO₄ with several nanoscales and AgBr combined with Zn_xPW₁₂O₄₀ are used to improve the activity and light stability of photocatalysts. And the catalytic activity evaluated by decomposed rhodamine B ?RhB? and acid red 18 ?AR18?. The exploration of photocatalytic mechanism is used to provide reference for synthesis of new type high-performance semiconductor. The main research results of this paper are as follows:?1? Different chemical reagents and precursors were added during the process of hydrothermal synthesis of several nanoscal ZnWO₄. In order to get Ag-ZnWO₄, a certain amount of Ag?NO₃?₂ and absolute ethyl alcohol were added in the progress of hydrothermal synthesis. The synthesized catalysts were characterized by scanning transmission electron microscope ?TEM?, scanning electron microscope ?SEM?, X-ray diffraction ?XRD?, UV-Vis diffuse reflectance spectrum ?UV-Vis DRS? and X-ray spectroscopy ?XPS? and so on, wich confirmed Ag⁰ doped onto ZnWO₄. In order to analyze the influence of the nanscal of ZnWO₄ and the concentration of doped Ag⁰, the photodegradation of RhB aqueous solution was investigated using various of catalysts under 300 Hg lamp. The result show that the catalyst with length/width=17.7, RAg=1% performances the most actively phcatalysis. A series of free radical scavenging experiments indicated that·OH was primary active species responsible for photodegradation of RhB by Ag-ZnWO₄-1?RAg=1%?. Photoluminescence spectrum implied that the recombination of photoelectrons and holes were prevented after doped Ag⁰. Finally we put forward and draw the photocatalyst degradation mechanism and path.?2? Zn_xPW₁₂O₄₀ with Hierarchical structure was synthesized through calcined the precursor customized on the template. The material was characterized by XRD, SEM, UV-Vis. Photocatalystic activity was evaluated by the degradation of AR18. To explore the best prepared condition of Zn_xPW₁₂O₄₀, the temperature, time during calcining and the ratio of precursors were change.?3? AgBr/Zn_xPW₁₂O₄₀ was synthesized by the method of ultrasonic wave radiation. The compound semiconductor was characterized by XRD? SEM?XPS?UV-Vis. And AR18 was used as target to investigate the photocatalytic activity. The impact on the phocatalytic activity by the content of AgBr was explored. A series of free radical scavenging experiments indicated that·O₂^- was primary active species.