Modification And Visible Light Propertie Of Bismuth Vanadate Catalysts

BiVO₄ photocatalytic material with narrow band gap has benificial of the non-toxicity,excellent stability and strong visible light absorption.The BiVO₄ is limited due to the low quantum yield and high recombination of the electron–hole pairs and so on.The improvement of BiVO₄ is studied in this paper,and modification by semiconductor coupling and metal ions doped.Photocatalytic activities of the BiVO₄materials were investigated by the degrading rhodamine B?RhB?as a probe reaction under visilible light irradiation.Products BiVO₄ were prepared with co-precipitation method?so called g-BiVO₄?and hydrothermal method?so called s-BiVO₄?,respectively.The structure,morphology and light absorption performance of the samples were characterized in the research.Results show that the BiVO₄ prepared by co-precipitation method and hydrothermal method are monoclinic scheelite,and the surface morphology is extremely different.The band-gap energy of the g-BiVO₄ and s-BiVO₄ are 2.47 eV and 2.42 eV,respectively,leading strong light absorption capacity in visible light.g-BiVO₄ and s-BiVO₄photocatalyst exhibited the photodegradation efficiency of RhB were 34%and 37%with under visible light irradiation with 60 min,respectivelyN-type CeO₂/p-type BiVO₄ heterojunction composite photocatalytic materials have been synthesized by a co-precipitation method and a subsequent annealing process.The as-prepared composites were characterized with a series of techniques.The results indicate that BiVO₄ and CeO₂/BiVO₄ are monoclinic scheelite,the morphology and the light absorption performance of BiVO₄ take place improvement.The light absorption in visible region and photocurrent of CeO₂/BiVO₄ is enhanced.Compared with pure BiVO₄,CeO₂/BiVO₄ exhibites significantly high photocatalytic activity for RhB degradation under visible light irradiation,the efficiency is raised 30.1%.The highest photocatalytic efficiency is observed when the mass ratio of CeO₂ and BiVO₄ is equal to20%and the degradation efficiency for RhB is 70%under visible light irradiation.During the first three runs,CeO₂/BiVO₄ composite material degradation efficiency for RhB still is 65%,indicating the photocatalysts is strong.The experiment shows that the enhanced activity is attributed to the p-n junction structure between BiVO₄ and CeO₂,and the p-n junction can reduce recombination of photogenerated hole-electron pairs,thereby the photocatalytic activity of the composite catalyst is improved.A series of Ni-BiVO₄ with different doping amount semiconductor materials were successfully synthesized by a hydrothermal method,and the as-prepared Ni-BiVO₄semiconductor materials were characterized.It is shows that the atomic ratio of Bi and V is close to 1:1,which is consistent with the ratio of Bi and V atoms in BiVO₄.Ni is present in the BiVO₄ lattice in the form of ions of+3 and doping Ni ions does not change the crystal structure of BiVO₄,but Ni ions can enter the gap of BiVO₄ crystal,which produces the lattice expand.The surface morphology of Ni-BiVO₄ photocatalyst changes,resulting in changes irregular particles to flakes after doping Ni.Compareing with BiVO₄,the BET of 0.75Ni-BiVO₄ increase about 10 m²·g^-1.The band gap of the semiconductor material narrow,its the absorption edge exhibits red-shifted and the reducing ability of BiVO₄ enhanced after doping Ni ion.Meanwhile,the charge resistance of 0.75Ni-BiVO₄ reduced and its instantaneous photocurrent density increased.The 0.75Ni-BiVO₄ and BiVO₄ photocatalyst exhibited the photodegradation efficiency of 96%and 44%,respectively,The stability and light corrosion resistance enhanced.The Ni³⁺plays a electron-trapping center in the BiVO₄ crystal,promoting the separation efficiency of electron-hole pairs and enstrengthening improved the photocatalytic activity of BiVO₄.