Synthesis Of Modified Bismuth Vanadate Photocatalyst And Performance For Degradation Of Dye Wastewater

This paper mainly includes two studies:one is to prepare uniform Bi@BiVO4 nanometer spheres and compare their photocatalytic performance with BiVO4;the other is to study the synergistic effect of fluorine ion substitution and adsorption on the charge transfer behavior and photocatalytic performance of BiVO4 through simple fluorination treatment(1)Uniform BiVO4 and Bi@BiVO4 nanospheres were prepared by a simple,harmless and low-cost method.Scanning electron microscopy(SEM),X-ray diffraction(XRD),ultraviolet visible diffuse reflectance spectroscopy(UV-DRS),electron diffraction(SAED)and fluorescence spectroscopy(PL)were used to characterize the morphology and structure of the two products.The results show that the degradation efficiency of Bi@BiVO4 is higher than that of BiVO4 under visible light.This is due to the formation of Bi@BiVO4 Schottky junction,which greatly inhibits the recombination efficiency of photogenerated electrons and holes in the semiconductor.Among them,the sample with the mass ratio of loading Bi of 10%(Bi@BiVO4=10%)has the best activity(2)Herein,a straightforward fluorination method is employed to enhance the photocatalytic performances of BiVO4.Compared with untreated BiVO4,the visible light activity of treated BiVO4 sample(0.15F-BiVO4,obtained with 0.15 g NH4F)has increased by about 1.4 and 4 times for degrading methylene blue(MB)and Rhodamine B(RhB),respectively.The activity enhancement is mainly due to the promoted charge transfer and separation by fluorine substitution for oxygen and surface fluorine adsorption.Fluorine substitution results in the formation of oxygen vacancy.Because of the high electron affinity,surface adsorbed fluorine,as well surface oxygen vacancy as electron trap,has improved charge separation effectively Moreover,oxygen can easily be captured by surface oxygen vacancies to form·O2-species,thus changing reaction pathway.In addition,surface adsorbed fluorine facilitates interfacial charge transfer between dye molecules and photocatalyst.