Preparation Of BiOI Photocatalyst And Photocatalytic Activity For Degradation Of Antibiotic Under Visible Light

Semiconductor photocatalysis technology has become a green and effective method to solve energy crisis and environmental purification.As a new type of semiconductor photocatalyst,BiOI has received extensive attention due to its unique layered structure,adjustable band gap and good visible light response.However,its high ratio of photogenerated electron-hole pair recombination limits its further improvement in photocatalytic performance.In this study,the photocatalytic properties of the materials were improved by controlling the morphology of BiOI and forming different junctions.In this paper firstly,we prepared BiOI nanoflowers and BiOI microplates by hydrolysis and hydrolysis methods respectively.Secondly,ultrasonic-assisted solvothermal method was used to prepare BiOI homojunction composed of BiOI nanoflowers and BiOI nanosheets.Finally,the AgI/BiOI heterojunction was prepared by in-situ ion exchange reaction.The crystal structure,elemental composition and chemical valence state of the composites were studied by X-ray diffractometer and X-ray photoelectron spectroscope characterization.The microstructures were characterized by scanning electron microscope and transmission electron microscope.The specific surface area and pores of the materials were investigated by the Brunauer-Emmett-Teller and nitrogen adsorption-analytical isotherms.UV-vis adsorption and photoluminescence study material light absorption properties and photo-carrier co-combination.Finally,the photocatalytic performance was evaluated by degradation of tetracycline hydrochloride.The photocatalytic mechanism of materials was explored through active factor capture experiments and binding band matching theory.The conclusions are as follows:(1)Compared with BiOI microplates,BiOI nanoflowers show good adsorption capacity and photocatalytic degradation ability for tetracycline hydrochloride.The adsorption rate after stirring for 30 min in darkness is47.41%,and the actual degradation rate of tetracycline hydrochloride after irradiation for 60 min is 49.36%.It is found that the larger specific surface area,stronger visible light absorption capacity and stronger reducing ability of electron are the main factors for the photocatalytic performance of BiOI nanoflowers;(2)For BiOI homojunction,the highest actual degradation rate of tetracycline hydrochloride is 69.43%,although the adsorption rate is 28.54%,which was lower than that of BiOI nanoflowers.The BiOI nanosheets were loaded on the surface and the void of BiOI nanoflowers.The formed BiOI homojunction reduces the recombination probability of photogenerated carriers;(3)AgI/BiOI heterojunctions exhibit good adsorption performance and photocatalytic degradation performance.In the second photocatalytic degradation performance test,the adsorption rate and actual degradation rate of the sample are higher than that of BiOI nanoflowers cyclic test experiments also show that the AgI/BiOI heterojunction has good reusability.AgI nanoparticles are distributed on the surface and voids of BiOI nanoflower,and the construction of heterojunctions reduces the recombination probability of photogenerated carriers.In this study,the separation efficiency of photogenerated electron-hole pairs was effectively improved by controlling the morphology of materials and constructing homojunctions and heterojunctions with matching energy band structures,and the performance of BiOI-based nanophotocatalysts was improved.The photocatalytic mechanism model was established and the transmission pathway of photogenerated electron holes was analyzed,which provided a theoretical and practical basis for the new BiOI composite photocatalyst.