Preparation And Photodegradation Properties Of BiOI Composites

In recent years,BiOI photocatalysts have attracted extensive attention due to their good chemical stability and excellent optical properties in terms of physicochemical properties.However,a single BiOI photocatalyst has a high recombination probability of photogenerated electrons and holes,and the photocatalytic activity is limited,so it cannot be efficiently applied in practice.Moreover,the powder has the disadvantages of being difficult to recover,insufficient contact with oxygen,and easy to cause secondary pollution.Therefore,this project intends to modify a single BiOI to prepare a binary composite photocatalyst BiOI/GO.In order to achieve the purpose of economical and recyclable utilization,a BiOI film with photocatalytic effect was prepared.The microscopic morphology,optical properties and degradation mechanism of different samples were investigated by scanning electron microscopy,N₂ adsorption and desorption,UV-Vis diffuse reflectance,X-ray energy spectrum analysis,photoluminescence spectroscopy,infrared spectroscopy and other characterization methods.The catalytic activity of the photocatalysts was evaluated by MB organic dyes simulating wastewater.The main conclusions are as follows:（1）Three-dimensional spherical BiOI photocatalysts were synthesized by hydrothermal method.The results showed that the degradation rate of MB was 67.71%within 120 min of the samples prepared at 120℃for 6 h.The degradation rate dropped to 8%through five repeated tests.Therefore,it has a stable degradation effect on MB.（2）The composite BiOI/GO catalyst was prepared by one-step hydrothermal method.The results show that the composite still exhibits a three-dimensional spherical structure after adding 2%GO.When the amount of catalyst added was 4 g/L,the degradation effect of the sample on MB was the best at 120℃for 6 h,which was 83.88%.Compared with the single BiOI catalyst,the degradation effect of the composite catalyst on organic dyes is significantly improved.It can be seen that the degradation effect is relatively stable through multiple cycle experiments on the same sample.（3）BiOI films were prepared by electrospinning technology.The results show that the film successfully solves the problem that the powder is difficult to recycle,the degradation effect on MB can reach 94.3%,and the degradation rate can still reach more than 93%after four cycles,and the film is only slightly damaged,showing excellent performance.The degradation performance and recycling stability of the ions were investigated,and the degradation mechanism was explored,indicating that（e^-）was the most important oxidizing species.In this thesis,a single BiOI was modified to improve its photocatalytic activity and reuse it.The prepared material has the characteristics of low pollution,low toxicity,economical efficiency and high degradation rate.Therefore,this material is considered to have great application value in the treatment of organic dye wastewater.