The Preparation And Photocatalytic Activities Of Bismuth Photocatalysts

TiO2 has became the most widely research of photocatalytic materials because of that it is nontoxic,cheap,easy to produce and stable.But it has a wide band gap and relatively high recombination rate of electron-hole pairs,resulting in a poor efficiency.So many strategies have been proposed to develop visible light photocatalytic materials with excellent photocatalytic activities.The preparation process of these approaches are complicated and high cost for popularization and application,and related research has entered a bottleneck stage.To develop high efficient use of the sun,and relatively simple preparation process of new photocatalytic materials have more practical meaning and become another new breakthrough.Spinel photocatalysts have been proven to be available and promising materials for environmental purification,and there are rare researches about bismuth photocatalytic materials.So in our work,we study the activities of bismuth photocatalytic materials.Bismuth photocatalytic materials were prepared by a special sol-gel method using acetone and glycerol as complexing agents,while glycerol acts mainly as a high boiling point solvent,stabilizer and coordinating agent to prevent the rapid hydrolysis of Bi(NO3)3,and nitric acid as solvent just to dissolve the solute.Differential thermal analyzer(DTA)was used to optimize the heat treatment mechanism.The structure,morphology,composition and light absorption property were characterized with XRD,SEM,EDS.We explored the photocatalytic efficiency of samples for the removal of reactive brilliant red K-2G dye solution under visible light.The XRD analysis show that the sample prepared at 600 ℃ has the structure of spinel CuBi2O4.It exhibits agglomerated morphologies with the diameter around hundreds of nanometers to several micrometers.The EDS spectrum further demonstrates that the sample is composed of stoichiometric Cu,Bi and O of spinel structure.The UV-Vis diffuse reflectance spectra show that the absorption edge of CuBi2O4 is extended greatly toward visible light and the band gap energy of CuBi2O4 is 1.6 eV.The 2 h degradation value of CuBi2O4 for brilliant red K-2G is 91.5%,the degradation value is still very high,above 80%after 5 times using.Sample MBi2O4(M = Ni,Zn)were synthesized by this special sol-gel method.The prepared samples were characterized by XRD,EDS and XPS analyses.The results indicated that ZnBi2O4 sample has the structure of spinel,which was no report before.The 2 h degradation values of NiBi2O4 and ZnBi2O4 for brilliant red K-2G are 82.7%and 99.8%,and the degradation values are 77.1%and 92.8%after 5 times using.Both of them exhibit good photocatalytic stabilities.A series of doping divalent metal ions and trivalent metal ions bismuth photocatalytic materials:A0.5B0.5Bi2O4(when A = Mg,B =Ni,Cu and Zn;when A = Ni,B = Cu and Zn;when A = Cu,B = Zn),AAlBi04 and AFeBiO4(A = Mg,Ni,Cu and Zn)were prepared by this new method.The results of photocatalytic experiments show that the AAlBiO4(A = Mg,Ni,Cu and Zn)series of photocatalytic materials have good thermal stability and photocatalytic activity.XRD analysis showed that AAlBiO4 series of bismuth photocatalysts may have the structure of spinel.The UV-Vis diffuse reflectance spectra show that AAlBi04 has good visible light response.Photocatalytic experiment of ZnAlBiO4 shows that it has excellent photocatalytic activity and photocatalytic stability.The degradation value is still above 95%after 5 times using,so ZnAlBiO4 has very good market application prospect.