Synthesis,Modification And Photocatalytic Performance Research Of Bismuth Oxyiodide

For several years,semiconductor photocatalytic technology as a new green catalytic technology was widly used in the water purification and water splittint.In this paper,the two Z-scheme heterojunction photocatalysts Ag-AgI/BiOI-Bi₂O₃ and GO/AgI/Bi₂O₃ were synthesized by modification of BiOI through the method of semiconductor composition,surface modification and morphological control.The as-synthesized photocatalysts were characterized by means of X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?,fourier transform-infrared spectroscopy?FT-IR?,scanning electron microscope?SEM?,transmission electron microscope?TEM?,surface area and pore?BET?and UV-vis diffuse reflectance spectrum?UV-vis DRS?.The photocatalytic properties of the as-prepared photocatalysts were investigated by using methyl orange?MO?as target pollutants under simulated solar light.Furthermore,the mechanism of the photocatalytic degradation was investigated by trapping experiment.The main contents are as following:1.Using ethylene glycol as solvent,different molar ratios of AgNO₃ were added to depose the AgI by in-situ ion-exchange,followed by photoreducing of metallic silver,and finally a series of Ag-AgI/BiOI-Bi₂O₃ composite photocatalysts were successfully synthesized via solvothermal method.The results show that the Ag-AgI/BiOI-Bi₂O₃ composite photocatalysts exhibit a micro-nano structure that the Ag-AgI nanoparticals and flake-like Bi₂O₃ deposing on the surface of cuboid-like structure assembled BiOI nanosheet.The results of photocatalytic dagradation of MO under visible light irradiation shown that the photocatalytic activities AgI/BiOI-Bi₂O₃ composite photocatalysts were enhanced after the deposition of AgI,and the photocatalytic activities Ag-AgI/BiOI-Bi₂O₃ composite photocatalysts were further enhanced after the photoreducing of metallic silver.Finally,the degradation kinetics and possible mechanism of the photodegradation of MO over Ag-AgI/BiOI-Bi₂O₃ photocatalysts were further explored.2.The BiOI with a flower-like sphere structure was synthesized by solvothermal method and modificated by silane coupling agent KH570 to combine with GO better.Using PVP as a surface active agent,the as-synthesized BiOI and different mass ratios of AgNO₃ were used to in-situ ion-exchange AgI,simultaneously,the BiOI was transformed into Bi₂O₃,finally the GO/AgI/Bi₂O₃composite system was abtained after the deposition of GO.The results show that the use of surface active agent and silane coupling agent has a great influence on the formation of the morphology structure.AgI nanoparticals were uniformity deposed on the surface of flower-like sphere structure assembled Bi₂O₃ nanosheet and the AgI/Bi₂O₃ composite was well-wrapped by gauze-like GO forming a core-shell structure.In the study of photocatalytic dagradation of MO under visible light irradiation,it can be found that the photocatalytic activities of GO/AgI/Bi₂O₃composite photocatalysts were obviously improved comparing with pure BiOI?Bi₂O₃ and AgI,and the main active groups for photocatalytic degradation of MO were the h⁺and·O₂^-radicals.Finally,the possible reaction mechanism of the photodegradation of MO was investigated and the Z-scheme mechanism was proposed.