Study On Morphology Modulation And Photocatalytic Properties Of Bismuth Vanadate

With the rapid development of modern industry, environmental pollution and energy depletion problems such as coal and oil in front of people, seriously affected the production and life of the people. On the occasion of the imminent get new energy and pollution control, a new technique that can use of solar photocatalytic degradation of organic pollutants and photolysis of water was found. BiVO₄ has a band gap of 2.4 e V, is one of the photocatalyst with visible light response. Due to the ease preparation, good stability and no toxicity, thus it attracts causing the great attention of researchers. The crystal morphology of photocatalyst has an important effect on the photocatalytic reactions. In this thesis,the photocatalytic perform of BiVO₄ was controlled through morphology control and surface treatment.Bismuth vanadate powders with different morphologies were synthesized by hydrothermal method. Spherical?tetragonal zircon crystal forms? and the plate?monoclinic scheelite polymorph? bismuth vanadate was synthesized by temperature control, respectively. At 170 ?, by changing the pH, concentration, adding SDBS surfactant we synthesized shuttle type, cruciferous type epitaxy needle rod and plate-like polyhedral bismuth vanadate.Different morphologies and crystal types of the prepared bismuth vanadate samples were characterized by XRD, DRS, RDS, EDS, SEM, TEM, PL, Uv-vis and other testing methods, and the sample composition, band gap structure, surface morphology and optical properties were also studied. The decolorization rate of methylene blue was used to evaluate the photocatalytic activity of different conditions of sample preparation. The results show that different crystal morphology of bismuth vanadate could be prepared under different conditions. And they have difference photocatalytic performance. When adding 0.1g SDBS surfactant, neutral pH, hydrothermal temperature being 170 ?, hydrothermal time being 12 h, the synthesis of plate?monoclinic scheelite structure?BiVO₄ powders have relatively obvious photocatalytic performance. Under simulated solar irradiation for 120 min, the rate of degradation of methylene blue increases 38.61 %.Plate-like morphology and shuttle type BiVO₄ powders were modified by Ag⁺ and Mn²⁺ treatment. The results show that the BiVO₄ exposured with?010? and?110? planes were loaded with Ag and MnO_x, forming Ag/BiVO₄ and MnO_x/BiVO₄ heterostructures. The Ag⁺ and Mn²⁺ surface treatment can improve the efficiency of charge separation in a certain extent, reduce the Ag-BiVO₄ and Mn-BiVO₄ photocatalyst band gap, thereby improving the performance of the modified photocatalyst.The photocatalytic activity of the treated photocatalysts were increased 30.02 % and 20.91 %...