Synthesis, Characterizntion And Visible-light Photocatalytic Performance Of Bismuth Vanadate Materials

From the viewpoint of the environment issues, the direct use of solar energy such as clean andrenewable energy for environmental pollution control has attracted great interest in recent years. Titaniumdioxide (TiO2) was found to be the most efficient photocatalyst under UV irradiation. However, TiO2can beonly excited by ultraviolet irradiation that corresponds to3-4%of the solar spectrum. So the developmentof visible-light responsive photocatalysts for environmental remediation has become an active research areain recent years. BiVO4has attracted great interest due to its potential applications in various technologicalfields because it exhibits interesting properties such as ferroelasticity, ionic conductivity andphotochromism. Recently, the photocatalytic activity of BiVO4has been recognized for the degradation oforganic materials, organic dyes. Considering the morphology and structure dependent properties of BiVO4,design and synthesis of BiVO4nanomaterials with novel structures are of special significance.The main contents of this thesis are listed as below:(1) Three-dimensional (3D) butterfly-like BiVO4were successfully synthesized by a simplesolvothermal method at a proper volume ratio (1:4) of EG/H2O mixed solution. It was found that ethyleneglycol (EG) had an obvious influence on the morphologies of the final products. BiVO4with differentmorphologies could be obtained by simply adjusting the volume ratio of the EG/H2O. The photocatalyticactivities of the samples were evaluated by decolorization of methylene blue (MB) under simulatedsunlight irradiation. The results demonstrated that BiVO4with butterfly-like morphology were better thanthat of BiVO4-1, BiVO4-3and BiVO4-4for photodegradation of MB. The monoclinic butterfly-likeBiVO4-2possessed bigger specific surface area, lower band gap energy and interesting morphology,resulting in the highest photocatalytic activity under simulated sunlight irradiation.(2) Monoclinic peanut-like BiVO4products have been successfully synthesized by a solvothermalmethod. The volume of CH3COOH and the concentration of NH3·H2O were found to play important rolesin the formation of this morphology. The optimal condition for preparation of highly active peanut-likeBiVO4samples are the volume of CH3COOH was5ml and the concentration of NH3·H2O was2mol/L.The photocatalytic activities of the as-fabricated BiVO4samples were measured for the photodegradation of Rhodamine B (RhB) under visible-light irradiation. The results demonstrated that BiVO4withpeanut-like morphology was better than that of others BiVO4samples for photodegradation of RhB.(3) Beautiful monoclinic BiVO4microspheres have been fabricated using the sodium dodecyl sulfate(SDS) assisted hydrothermal strategy with bismuth nitrate (Bi(NO3)3·5H2O) and ammonium metavanadate(NH4VO3) as metal source. The physicochemical properties of the materials were characterized by meansof the XRD, SEM, TEM, BET, and UV–vis techniques. The photocatalytic activities of the as-fabricatedBiVO4microspheres were measured for the photodegradation of methylene blue (MB) under visible-lightirradiation. The effects of SDS on the synthesis of BiVO4microspheres were investigated. Comparisonexperiments were carried out and showed that the amount of SDS makes significant influence on themorphology of the products. The possible formation mechanism of such BiVO4microsphere material hasalso been discussed.