Preparation And Photocatalytic Performance Of Ternary Metal Compound Photocatalyst

With the rapid development of human society, energy crisis and environmental pollution has become an increasingly pressing issue. It has been noted that the stock of non-renewable energy has been declining alarming so that seeking effective method of using renewable energy becomes increasingly urgent. In recent decades, photocatalyst, which can be used to obtain clean and environmental hydrogen by photo-splitting water effectively or to solve the problem of water pollution by degradating organic macromolecules in sewage, is gaining more and more attention and widely research. In this paper, we study two kinds of very promising photocatalyst: CaIn₂S₄ and CuWO₄, including their preparation, modification methods and photocatalytic degradation performance of organic dyes. On the one hand, we added different surfactant and changed their content to control the preparation of CaIn₂S₄ photocatalyst. On the other hand, the two composite photocatalysts g-C₃N₄/CaIn₂S₄, g-C₃N₄/CuWO₄ were synthesized. These as-prepared samples were characterized by a series analysis methods to study their crystal structure, morphology, chemical composition, optical absorption performance, the specific surface area. At the same time, the photocatalytic performance of all samples was evaluated by degradation of organic dyes solution under visible light irradiatio, the results showed that the photocatalytic activity of photocatalyst has a certain degree of improvement after modification, main research content is as follows:（1） CaIn₂S₄ photocatalysts were synthesized by hydrothermal method used In（NO3）3·4.5H2 O, Ca（NO3）2·4H2O and CH3CSNH2 as raw materials and its synthesized was controlled by adding surfactant PVP and CTAB respectively. The crystal structure, morphology and optical properties of samples were characterized by X-ray diffraction（XRD）, scanning electron microscope（SEM）, UV-Vis diffusion reflectance spectra（DRS） and BET analysis. According to the analysis of experimental results, the samples with high purity were prepared by adding a certain amount of surface active agent to control their morphology, structure and optical properties. Rhodamine B（RhB） was used as a degradation solution in the photocatalytic tests under visible light illumination.（2） A series of g-C₃N₄/CaIn₂S₄ composite photocatalysts were prepared by hydrothermal synthesis method. The crystal structure, morphology, optical absorption properties and specific surface areaof the photocatalysts were characterization by using XRD, SEM, TEM, FT-IR, UV-Vis, BET. XRD and TEM image results show that g-C₃N₄/CaIn₂S₄ samples were successfully prepared by hydrothermal synthesis and the addition of g-C₃N₄ won’t change the crystal of CaIn₂S₄. The SEM images, BET measurement and UV-Vis spectrum diagram indicate that the addition of g-C₃N₄ can influence the morphology, specific surface area and reduce visible light absorption of CaIn₂S₄. The degradation of RhB results show that the g-C₃N₄/CaIn₂S₄ composite photocatalyst has better catalytic properties than pure CaIn₂S₄. At the same time, the mechanism of g-C₃N₄ addition enhanced the photocatalytic activity of CaIn₂S₄ is discussed.（3） First, CuWO₄ precursor was prepared by settlement, then calcined in 700 ℃. g-C₃N₄ was selected as composite materials to improve the performance of CuWO₄. A series of g-C₃N₄/CuWO₄ samples were prepared. These as-prepared samples were characterized by XRD, SEM, UV-Vis, FT-IR. The effect of g-C₃N₄ content on photocatalytic performance of methylene blue（MB） degredation under visible light illumination was investigated.