Study On Preparation And Photocatalytic Properties Of Bismuth-related Composite Photocatalysts

Bismuth-related photocatalysts have attracted more and more attention because its lower Eg enhances its available absorption under visible light.Among them composite-oxide catalyst has been one kind of most promising photocatalysts due to the diversity of crystal and electronic structure.This diversity make it possible to realize visible-light response and high transfer rate of charge carriers meanwhile.Monoclinic phase of BiVO4 has been one of the most active OER photocatalysts because of its relatively low band gap of-2.4 eV.However,the low separation efficiency of photo-induced electron-hole pairs restricts its extensive application in oxygen evolution reaction(OER).On the contrary,BiOCl possesses high separation efficiency of photo-induced electron-hole pairs and high transfer rate of charge carriers.Yet,the narrower photo-response range,complicated photocatalytic mechanism and low visible-light activity inhibit its photocatalytic activity.This article introduces the band structure,optical properties,photocatalytic and photoelectrochemical performance of BiVO4 and BiOCl.The details are as follow:1.Monoclinic BiVO4 nanomaterial was obtained by hydrothermal and solvothermal methods.BiVO4 was successfully synthesized by hydrothermal method.In addition,lamellar and dendritic BiVO4 were synthesized by adding moderate amount of TiCl4 and CTAB,respectively.BiVO4 nanocrystal was synthesized by solvothermal method,and the influence of solvent and reaction temperature have been discussed in detail.2.The Bi/BiVO4/V2O5 composite was successfully synthesized by a facial method.The Bi/BiVO4/V2O5 composite was obtained by annealing BiVO4 nanocrystals in Ar-H2 atmosphere.The component of composite was proved by XRD,Raman and XPS tests.The superior photocatalytic performance of Bi/BiVO4/V2O5 composite was tested by water oxidation reaction(2413 ?mol·g-1·h-1),which was better than Bi2VO5.5/BiVO4/V2O5(annealing in vaccum)and BiO/BiVO4/V2O5 composite(annealing in air).The production of metal Bi enhances the transfer of charge carriers and improves the photocatalytic efficiency of Bi/BiVO4/V2O5 composite.3.BiOCI and BiVO4/BiOCl materials were prepared by solvothermal methods.The content of BiOCl in BiVO4/BiOCl can be controlled by regulating the amount of hydrochloric acid.Relative to BiVO4,BiVO4/BiOCl possesses higher photocatalytic efficiency in the photocatalytic degradation of RhB.The high photodegradation ability of BiVO4/VBiOCl results from the formation of p-n junction between BiVO4 and BiOCl,which promotes the separation of electron-hole pairs.The phototocatalytic mechanism was discussed in detail.