In-situ Synthesis And Photocatalytic Properties Of BiOBr Modified Materials

Photocatalytic technology has a promising prospect in solving environmental problems because photocatalyst can induce organic degradation under solar energy.The efficient and inexpensive photocatalysts are the basis for development of the technology.The internal electric field and the electron indirect transition mode formed by layered BiOBr are conducive to the separation of electron-hole pairs.Therefore,BiOBr has attracted the attention of researchers who have done a lot of work about them.A large number of studies have been found that single-component BiOBr has the defects of low quantum efficiency and narrow light absorption range,which makes the photocatalytic performance of BiOBr still have a great improvement space.In this paper,Bi OBr as a substrate was used to synthesize BiOBr/BiPO₄and BiOBr/Bi/BiPO₄ composite photocatalysts in situ.The purpose is to enhance the photocatalytic activity of BiOBr by the p-n heterojunction and local surface plasma resonance?SPR?effect of semimetal Bi.The prepared composite photocatalysts were characterized by using various methods.Its corresponding physicochemical properties and its possible photocatalytic mechanism were determined.The main contents are as follows:1.Study on in-situ synthesized BiOBr/BiPO₄ composite photocatalystIn this article,BiOBr/BiPO₄ composite photocatalyst was prepared via anion exchange method through in situ growing BiPO₄ on the surface of BiOBr.The as obtained BiOBr/BiPO₄ composite photocatalyst was characterized by X-ray diffraction?XRD?,scanning electron microscope?SEM?,UV-Vis diffuse reflection spectra?UV-Vis DRS?and transient photocurrent.The photocatalytic performance of as-obtained Bi OBr/BiPO₄ photocatalyst was evaluated by the degradation of MO under simulated sunlight irradiation.The test showed that the degradation efficiency of BiOBr/BiPO₄ composite photocatalyst was much higher than that of BiOBr and Bi PO₄ single component.When BiOBr and BiPO₄mole ratio is 9:3,the composite exhibited the highest photocatalytic performance.This may be due to the fact that the in situ growing BiPO₄ formed tight p-n heterojunction interface with BiOBr.The heterojunction reduces the recombination efficiency of photo-generated electrons and holes,and enhances the separation efficiency of BiOBr/BiPO₄ composite photocatalyst.2.Study on in-situ synthesized BiOBr/Bi/BiPO₄ photocatalystThe BiOBr was used as the substrate,the Bi element can be reduced on the surface of Bi OBr after addition of NaBH₄.Then the BiOBr/Bi/Bi PO₄ composite photocatalyst was prepared by adding the same amount of H₃PO₄.The molar ratio between the three components is adjusted by the amount of Na BH₄ added.The BiOBr/Bi/BiPO₄ composite photocatalyst was characterized,and methyl orange was used as the target degradant to test its degradation activity under visible light.The results show that the photocatalytic activities of BiOBr/Bi/BiPO₄ composites with different molar ratios are different,and the photocatalytic activity is best when the amount of NaBH₄ is 10 mmol/L.The degradation rate did not change significantly after being used six times.The excellent photocatalytic activity of BiOBr/Bi/Bi PO₄ composite photocatalyst is attributed to the SPR of elemental Bi,which broadens the light absorption range of the catalyst and the electron-hole separation efficiency.