Preparation And Photocatalytic Property Of Bismuth Oxyiodide-based Composite Photocatalysts

Semiconductor photocatalysis technology currently provides an effective solution for the energy shortage and environmental pollution problems worldwide.Semiconductor photocatalysis technology can utilize the solar energy and have the advantages of environmental friendliness and high efficiency.As a new type of semiconductor photocatalytic material,BiOI has a narrow band gap that it can make full use of visible light resource.It also has a unique crystal structure that is made up of[Bi₂O₂]²⁺layer and I^-layer.However,there is a problem in the application of BiOI.The separation efficiency of photogenerated electron-hole pairs is low,and combination probability is high.In order to eliminate this defect,we construct a variety of heterojunction photocatalytic materials based on BiOI,which effectively improves the separation and migration efficiency of the photogenerated carriers,thus improving the photocatalytic performance.The specific research contents are as follows:Polypyrrole?Ppy?was prepared by oxidative polymerization.Ppy/BiOI composite was prepared by adding Ppy in the process of hydrolysis.High resolution TEM revealed the interface contact between Ppy and BiOI nanomaterials,and proved the formation of heterojunction.The photodegradation experiment of RhB showed that 5%Ppy/BiOI has the best photocatalytic performance and the degradation efficiency was 6 times that of BiOI.The results showed that the good conductivity of Ppy contributed to the rapid separation and transfer of photoinduced electron-hole pairs of BiOI,thus directly enhancing the photocatalytic activity of Ppy/BiOI composites.On the basis of Ppy/g-C₃N₄ composite,g-C₃N₄/Ppy/BiOI was prepared by in-situ composite method.By adjusting the content of Ppy and BiOI in the preparation process,the optimal composite 15%PCN?20?/BiOI was obtained,and the photodegradation efficiency of methyl orange?MO?was 2 times that of BiOI.The research showed that the holes generated from g-C₃N₄ and BiOI were transferred to Ppy after light excitation,which could effectively separate the photogenerated electron-hole pairs and enhance the photocatalytic activity.In the process of BiOI preparation,different proportions of Cu₂O were added,and two kinds of composite products CuI/BiOI and Cu₂O/CuI were prepared by the precursor transformation strategy.The results showed that the photocatalytic activity of CuI was higher than that of BiOI.The photocatalytic ability of Cu₂O/CuI composites was obviously improved,and 90%of MO could be photodegraded within4 hours.The photoluminescence and photochemical experiments showed that separation of photogenerated electrons and holes of Cu₂O/CuI was more efficient.The concentration of superoxide radical produced by the Cu₂O/CuI-2 was also increasing to 6 times that of CuI.However,the energy band structure of CuI/BiOI composite is not conducive to charge separation and transfer,so its performance is little improved.