Controllable Synthesis And Photocatalytic Performance Of Tungsten Oxide And Its Composites

In this thesis,the hydrothermal method was used to synthesize WO₃ catalyst materials with controlled morphologies and structures by changing the amount of reactants,reaction temperatures and reaction time.The effect of the structure and morphology of WO₃ on the photocatalytic properties was investigated.The WO₃/ZnO and WO₃/TiO₂ composites were prepared by compositing,which improved the photocatalytic performance of WO₃.The main contents are as follows:?1?The monoclinic phase tungsten oxide?m-WO₃?cube structure was synthesized from commercial WO₃ and hydrogen peroxide.The influence of reaction temperature on the structure and morphology of m-WO₃ was investigated.The results show that the pure WO₃·0.33H₂O crystal is synthesized at a hydrothermal temperature of 150?,the mixed crystal phase of WO₃·0.33H₂O and WO₃ is synthesized at 200?,and the pure WO₃ sample is prepared at 240?.The photocatalytic performance of the m-WO₃sample was studied by photocatalytic degradation of methylene blue solution using a xenon lamp to simulate sunlight.The photocatalytic efficiency of the sample at 240? was highest in the prepared WO₃ samples,the efficiency can reach 100% in 210 min.?2?Using commercially available WO₃ and ZnO as tungsten source and zinc source,and hydrogen peroxide as solvent,n-WO₃/ZnO?n=5%,10%?nanocomposites were prepared by adjusting the amount of commercial WO₃.The effect of the amount of commercial WO₃ on the morphologies,structures and photocatalytic properties of WO₃/ZnO samples was investigated.The photocatalytic degradation experiments of methylene blue solution proved that the synthesized 5%WO₃/ZnO sample has excellent photocatalytic effect on methylene blue at room temperature,and can completely degrade methylene blue in 30 min.?3?WO₃/TiO₂ materials were synthesized from commercial WO₃ and TiO₂ as tungsten source and titanium source.When 0.1g and 0.2g of commercial WO₃ were added separately,the structures and morphologies of WO₃/TiO₂ samples were investigated.The results show that the synthesized WO₃/TiO₂ samples have good photocatalytic effect at room temperature,among which 5%WO₃/TiO₂ sample has the highest photocatalytic degradation efficiency,and it takes only 70 min to achieve a degradation efficiency of 100%.?4?Using commercially available tungstic acid?H₂WO₄?and hydrogen peroxide as precursors,h-WO₃ rod-like structural materials were synthesized by one-step hydrothermal method.The effects of reaction temperatures,types and amount of structure-directing agents on the crystal phases and morphologies of h-WO₃ products were investigated,and the photocatalytic performance of h-WO₃ sample was studied by photocatalytic degradation of methylene blue solution.The results show that the morphology of the sample synthesized after adding Na₂SO₄ is irregular,and the sample synthesized after adding NaNO₃ is a regular rod-like product,so NaNO₃ is selected as a structure-directing agent to synthesize hexagonal phase tungsten oxide.Finally,the photocatalytic properties of the sample prepared under the conditions of 120? and 2g NaNO₃ were studied.The results show that h-WO₃ has higher photocatalytic degradation activity than m-WO₃,and the time taken for methylene blue to completely degrade is shorter.