The Controllable Synthesis And Study On Photocatalytic Properties Of Nanoscale Bismuth Sulphide And Compound Materials

Nowadays,with the rapid development of society and economy,more and more environmental and nature resource issues need to be dealt with.Among these problems,the treatment of industrial wastewater and organic dye wastewater is particularly important.Semiconductor photocatalytic technology,which has the characteristics of low cost,green environment and so on,has been gradually applied in the field of effluent disposal.Over time,this technology has become matured.The principle of photocatalytic degradation of organic dyes is that when sunlight shines on the photocatalyst,the catalyst absorbs photons whose energy is greater than or equal to the gap in its own energy band,and electrons in the valence band of the catalyst are excited to the conduction band,while the valence band forms a hole.Then the electron-hole pair is separated,and the reductive electrons form superoxide radicals by combining with oxygen,and the oxidative holes form hydroxyl radicals by combining with water molecules.The superoxide radicals will eventually be transformed into hydroxyl radicals with strong oxidation,and the organic dye molecule will be degraded into harmless inorganic substance.Bismuth Sulfide semiconductor nanomaterials is a new type photocatalyst,which is non-toxic,pollution-free,low cost and full absorption of visible light.In this paper,the effects of different synthesis conditions on the preparation of nano-bismuth sulfide were studied,and the photocatalytic properties of bismuth sulfide composite with different carbon materials were also investigated.The main contents and results were as follows:?1?Bismuth sulfide nanomaterials were prepared by hydrothermal method Using bismuth nitrate pentahydrate and thiourea as reactants.The crystallinity,morphology and optical properties of the samples were studied by transmission electron microscopy?TEM?,UV-Vis spectroscopy and fluorescence spectroscopy.The experimental data of different ratios of reactants showed that excessive sulfur source is beneficial to the formation of bismuth sulfide with good crystallization.The experimental results of different reaction solvents showed that the morphology of the product was uniform when using glycerol as solvent.More Bi₂S₃ nano-flowers can be obtained by adding surfactant,and it plays a role in preventing aggregate of products.We also found that the size of bismuth sulfide nano-flower increased obviously with the increase of temperature,and the size of bismuth sulfide nano-flowers increased to a certain extent with the increase of synthesis time.The morphology of the product is changed from nanowires to nanobeams.We found that the best product was obtained by using glycerol as solvent with excessive sulfur source at reaction temperature of 120 ? for 12 h.It has good optical properties and has a strong absorption of visible light below 900 nm.Its fluorescence emission peak appears at the wavelength of 778 nm.?2?Bi₂S₃/C₃N₄ nanocomposites were prepared by one-step calcination using ammonium thiocyanate and bismuth chloride as precursors,.The effects of different bismuth sulfide content,different calcination temperature and sulfur source on the composition and structure of product were investigated.At the same time,the photocatalytic ability of the nanocomposite to Rhodamine B dyes was studied.It was found that the photocatalytic performance of the products was little different synthesized from different sulfur sources.When the reactant ratio of Bi₂S₃/C₃N₄ nanocomposites is 0.5%,the photocatalytic efficiency is the best,and the degradation rate of dye can reach 90%after 30 minutes of illumination.The photocatalytic efficiency of composites increases gradually with the increase of calcination temperature.?3?Bi₂S₃/RGO nanocomposites were prepared by one step hydrothermal method using bismuth nitrate pentahydrate and thiourea as reactants and thiourea acts as reducing agent.The effects of GO content on the morphology of the products were investigated.The photocatalytic performance of difference samples was also studied.The photocatalytic results of Rhodamine B showed that when the content of GO was 60mg,the photodegradation efficiency of Bi₂S₃/RGO nanocomposites was the best.The photocatalytic mechanism was preliminarily investigated.It was found that the decolorization efficiency of catalyst was inhibited by the addition of isopropanol and the penetration of nitrogen.However,the addition of silver nitrate solution significantly promoted the degradation efficiency.It is concluded that electron holes and different free radicals play an important role in photocatalytic systems.