Tuned Synthesis And Properties Investgation Of Bismuth Tungstate Nano-Structures

As a new kind of photocatalyst, Bi2WO6 has drawn the attention of researchersdue to its narrow band gap (2.75 eV) and potential application in solar energyutilization, development of new energy and environmental aspects. The morphologyand size of nanometer materials have significant effect on their properties. It becomesan important research topic to synthesize Bi2WO6 with various morphologies andimprove its catalytic performance.Bi2WO6 hollow nano-spheres, nano-flakes and hexagon sheets were synthesizedvia solvothermal process with the hydrolysis products of Bi(NO₃)3 as Bi sourcetemplates. The influence of experimental conditions on the morphology and structureof Bi2WO6 were studied with Transmission electron microscopy (TEM), Scanningelectron microscopy (SEM), X-ray diffraction (XRD), UV-vis and Electrochemicaltest. The formation mechanism of Bi2WO6 with various morphologies was alsopresented. The main points in this dissertation are summarized as follows:1) Rectangle blocks of Bi source templates of 20-30μm long, 2μm wide and 2μm thickwere yielded after Bi(NO₃)3 aqueous solution was aged for 30min. Rectangle flakes ofBi2WO6 with 5-10μm long and 100-200nm thick were obtained from the Bi sourcetemplates in ethanol-water mixed solvent (10:1) after solvothermal treatment at 100℃for 10 h.2) Nano-spheres of Bi source templates with diameter of 30-50nm were yielded whenBi(NO₃)3 aqueous solution was added to ethanol-water mixed solvent (10:1). Welldispersed Bi2WO6 hollow nano-spheres with diameter of 30-50nm and shell thicknessof 10nm were obtained from the Bi source templates after solvothermal treatment at100℃for 10 h. 3) Well defined hexagon sheets of Bi source templates of 500 nm wide and 100nmthick were yielded when Bi(NO₃)₃ aqueous solution was added to ethanol-water mixedsolvent (10:3). Bi₂WO₆ hexagon sheets of 500 nm wide and 100nm thick wereobtained from the Bi source templates after solvothermal treatment at 100℃for 10 h.4) Bi₂WO₆ nanostructures were synthesized through interface reactions inethanol-water mixed solvent with Bi source templates as sacrificial templates.Systematic studies of the influence of reactants concentrations, ratio of ethanol towater, solvothermal temperatures and solvothermal time on the morphologies ofBi₂WO₆ nanostructures were conducted. The Bi₂WO₆ nanostructures exhibitedsignificant photocatalysis property.Innovations of this dissertation: 1) Bi₂WO₆ hollow nano-spheres with uniform sizewere synthesized via sacrificial templates in ethanol-water mixed solvent. 2) A noveltuned synthesis method was presented to synthesize Bi₂WO₆ nanostructures throughinterface reactions applying the hydrolysis products of Bi(NO₃)3 as sacrificialtemplates.