Facile Synthesis And Photocatalytic Properties Of Bismuth Tungsten Molybdenum Oxides

Bi2WxMo1-xO6has the pyroelectric, ferroelectric/piezoelectric, ion-conductive andnon-linear dielectric coefficient properties. The band gap of Bi2WxMo1-xO6is2.5-2.7eV,which has a potential value and practical significance on photocatalytic propertiesbecause of the response to the visible light. In this thesis, Bi2WO6, Bi2MoO6andBi2WxMo1-xO6solid solution with different morphology and particle size weresynthesized by hydrothermal method. The influence of different reaction conditions onthe morphology and particle size was discussed. The photocatalytic properties ofbismuth tungsten molybdenum oxide were investigated using Rhodamine B as the mainobjective of photocatalytic degredation, and the main impact factors of thephotocatalysis under the visible light were discussed.Bi2WO6powders with varieties of morphologies were prepared usingNa2WO4·2H2O and Bi(NO3)3·5H2O as raw materials via a simple hydrothermal methodby changing the pH, using different surfactants and solvents. The phase compositionand morphology were characterized by X-ray diffraction (XRD), scanning electronmicroscopy (SEM), UV-vis diffuse reflection (UV-vis) etc. The results indicated thatBi2WO6showed better photocatalytic activity under the synthetic conditions of pH=9.5,CTAB as surfactant and ethylene glycol as solvent. The degredation ratio of the threesamples of rhodamine B under metal halide lamp irradiation for2h reached up to94%,92%and90%, respectively. Meanwhile Bi2WO6was doped by transition metal ionsFe3+, Cu2+, Ni2+using an impregnation method. The degredation ratio of the three dopedBi2WO6towards rhodamine B increased by13%,11%and11%, respectively.Bi2MoO6powders with varieties of morphologies were prepared using(NH4)6Mo7O24·4H2O and Bi(NO3)3·5H2O as raw materials via a simple hydrothermal method by changing the pH, using different surfactants and solvents. The phasecomposition and morphologies were characterized by XRD, SEM, UV-vis etc. Theresults illustrated that Bi2MoO6showed better photocatalytic activity under thesynthesis conditions of pH=9.5, using PEG2000as surfactant and ethanol as solvent.The degredation ratio towards rhodamine B reached up more than70%under metalhalide lamp irradiation for2h. With the cocatalyst of hydrogen peroxide and Bi2MoO6powder prepared with anhydrous ethanol as solvent, rhodamine B and methylene bluewere degraded by a ultrasonic bath. The influence of additive amount of catalyst,hydrogen peroxide and ultrasonic time on degredation ratio was investigated. Theresults indicated that the better photocatalytic activity was obtained when additiveamount of catalyst was10.0mg, hydrogen peroxide was0.10ml and ultrasonic time for15min. The degredation ratio of rhodamine B reached up to95%and84%, respectively.Bi2MoO6was doped by transition metal ions Fe3+, Cu2+, Ni2+using an impregnationmethod. The degredation ratio of the three doped Bi2MoO6towards rhodamine Bincreased by11%,7%and4%, respectively.Bi2WxMo1-xO6solid solution with varieties of morphologies were prepared usingNa2WO4·2H2O,(NH4)6Mo7O24·4H2O and Bi(NO3)3·5H2O as raw materials via a simplehydrothermal method by using CTAB as a surfactant, deionized water or ethyleneglycol as a solvent. The results showed that Bi2WxMo1-xO6solid solution synthesizedusing CTAB as surfactant and glycol as solvent showed better photocatalytic activitywhen x=0.5, the degredation ratio of which towards rhodamine B under metal halidelamp irradiation for2h reached up to66%and99%, respectively. In the series ofsamples prepared by hydrothermal method, Bi2WxMo1-xO6solid solution showed betterphotocatalytic activity when x=1, the degredation ratio of which towards rhodamine Breached up to98%under metal halide lamp irradiation for2h. The degredation ratio ofhydrothermal processed Bi2WxMo1-xO6towards rhodamine B reached up to74%whenx=0.5.