Study The Synthesis And Modification Of New Vanadate System Photocatalysts

In recent years, facing the increasingly serious environmental pollution problem,more and more human、material and financial resources to be invested in environmentmanagement studies. Photocatalysts and photocatalytic oxidation process as the mostefficient approach to the govering of environment in currently which is drawing moreand more attation. BiVO₄and LaVO₄photocatalyst powders were synthesized byLow-temperature molten salt method to sodium metavanadate（NaVO₃·2H₂O） as Vsource, bismuth chloride（BiCl3） as Bi sourece and lanthanum nitrate（La（NO₃）₃·6H₂O）as La soure. Have a research on the crystal、crystallinity、morphology and partical sizeof samples by X-ray diffraction、scanning electron microscope、transmission electronmicroscope and UV-Vis spectrophometer. And Cu/BiVO₄composite photocatalystpowders were synthesized turn on it with copper nitrate（Cu（NO₃）2·3H₂O） as additivesand have a study of the influence of Cu doping BiVO₄to its photocatalytic activity.（1） XRD patterns of BiVO₄photocatalyst powders indicated that the crystallinephase of BiVO₄was tetragonal under the calcining temperature of200℃, and thecrystalline phase well converted to monoclinic when the calcining temperature up to270℃. SEM showed that the particle size decreased with the improvement ofcalcining temperature. UV-Vis spectra revealed that BiVO₄both have fine property oflight absorption in ultraviolet light and visible light area. The area of visible lightabsorption of monoclinic BiVO₄was more wider than tetragonal BiVO₄.（2） XRD patterns of LaVO₄photocatalyst powders indicated that the crystallinephase of as-prepared samples were monoclinic. TEM showed that the increase ofcalcining temperature can promote the crystallization development of LaVO₄andimprove crystallinity; The addition of molten salt can significantly improve thecrystallinity of LaVO₄compared to the molten salt was not added. UV-Vis spectrarevealed that the biggest light absorbing boundary of LaVO₄was in ultraviolet areaand it have had a corresponding red shift with the increase of calcining temperature.（3） XRD patterns of Cu/BiVO₄composite photocatalyst powders indicated thatCu doping BiVO₄have not changed its crystalline phase and the crystalline phase of Cu/BiVO₄was still monoclinic. Cu is exist in Cu/BiVO₄composite in the form ofCuO and it is just compounded in the surface of BiVO₄yet not enter into lattice. SEMshowed that the particle size have decreased significantly after Cu doping BiVO₄.UV-Vis spectra revealed that the light absorbing boundary of Cu/BiVO₄compositephotocatalyst powders was about at620nm and it was still have a higher intensity oflight absorption in the visible region600⁸00nm. Cu/BiVO₄composite showed morebetter light absorption and more higher photocatalystic activity than pure BiVO₄.