Synthesis Of Bismuth Oxyhalides And Their Composites Photocatalysts At Low Temperature And Study Of Their Properties

With the continuous understanding and research of semiconductor photocatalytic materials,people have found that it has a great help to solve the environmental pollution and energy crisis.The development of the technology,however,is restricted by the high recombination of the optical electrons and holes,and the narrow range of the light response.On the other hand,due to the current most of literatures of photocatalyst prepared by hydrothermal method and prepared photocatalyst technology at low temperature is beneficial to control the microstructure of products,energy saving and industrial production.Herein,a series of structure-controlled bismuth oxyhalide and their composite photocatalysts have been synthesized with Bi（NO₃）₃ as bismuth source at low temperature.The photocatalytic activities for different pollutants degradation were also discussed.And the details are as follows:（1）Uniform hemispherical Bi₁₂O₁₇Br₂ was fabricated with the CTAB and Bi（NO₃）₃ as materials in urea solution at low temperature.Flowerlike and sheetlike Bi₁₂O₁₇Br₂ were obtained while the urea solution was replaced by ethylene glycol（EG）or glacial acetic acid（HOAc）solution.Similarly,the usage of CTAC and KBr as a chlorine and bromine source in urea solution led to the formation of BiOCl aggregated nanosheets and BiOBr nanoparticles,respectively.The photocatalytic and adsorption performance of bismuth oxyhalides which were obtained by using CTAB,KBr and CTAC were evaluated with RhB,CV and MO under visible light irradiation,the results showed that the hemispherical Bi₁₂O₁₇Br₂ possessed good photocatalytic performance for RhB and CV degradation and adsorption properties due to the unique pore structure and higher surface areas.（2）Bi₂S₃/BiOBr（denoted as BS-BC）composite was prepared by using thiourea solution as solvent to dissolve Bi（NO₃）₃ and KBr as Br source at low teperature,then Bi₂S₃/BiOCl and Bi₂S₃/（BiO）₂CO₃（respectively denoted as BS-BC and BS-BOC）were obtained while the KBr was substituted for KCl and Na2CO₃.Meanwhile,thiourea solution can be used not only as a solvent but also as a source of sulfur.In addtion,the content of Bi₂S₃ can be controlled by changing the reaction temperature,reaction time,the amount of thiourea and the molar ratio of Br/Bi in BS-BB complex.Finally,the photocatalytic activity of these composites and their single phase is studied under visible light irradiation,the flower-like BS-BB showed better photocatalytic activity for CV and RhB due to its unique microstructure.