Cotrollable Biomimetic Synthesis And Photocatalytic Performance Of BiVO₄as An Efficient Visible Light Photocatalyst

BiVO4semiconductor as environmentally-friendly photocatalyst could be excited by visible lightbecause of its smaller band gap. On account of its numerous advantages such as non-toxic, non-pollutionduring degradation of organic pollutants, mild preparation conditions, BiVO4has been paid more and moreattention to.In this paper, BiVO4samples with special morphologies could be prepared by biomimetic method underdifferent matrix conditions. The prepared samples were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM), Brunauer-Emmet-Teller (BET) and UV-Vis diffuse reflectancespectra. Photocatalytic activities of BiVO4samples were evaluated by the degradation of RhB under visiblelight. The results are as follows:(1) Hierarchical BiVO4photocatalysts with different morphologies such as twins-like ball,cauliflower-like, windwill-like, and ellipse-like were prepared by using starch as template viahydrothermal route. The pH value, reaction temperature, reaction time and amount of mannitol have greatinfluences on the morphology, crystallinity and photocatalytic activity. The experiments indicated that thedifferent pH value would result in different morphologies. Moreover the possible growth mechanism ofdifferent morphologies was proposed. The results demonstrated that windwill-like samples prepared atpH=4, along (040) growth, possessed excellent photocatalytic degradation of RhB under visible light.(2) The ellipse-like BiVO4photocatalyst was synthesized by using yeast as biotemplate via biomimoticmethod. The degradation efficiency of the samples can reach96.5%under visible light irradiation.(3) BiVO4photocatalyst was obtained by gelatin assisting hydrothermal way. The different morphologies could be obtained under different pH conditions. The photocatalytic activities of samples were evaluatedby the degradation of RhB. The results indicated that the maple-leaf-like monoclinic BiVO4photocatalystswith good crystallinity were prepared at pH=4,180℃for24h with adding0.25g amount of gelatin. Thedegradation efficiency of RhB could reach96.4%within280min under visible light irradiation.(4) BiVO4photocatalyst with Bismuth nitrate (Bi(NO3)3·5H2O) and ammonium vanadate (NH4VO3) asraw materials could be prepared by mannitol assisting hydrothermal way. The PH value, reactiontemperature, reaction time and amount of mannitol have great influence on the morphology, crystallinityand photocatalytic activity. The results demonstrated that the samples synthesized at pH=3,180℃for24hwith adding0.164g amount of mannitol had a higher photocalytic degradation activity.