Modification Of Bi₅Nb₃O₁₅ And Its Photocatalytic Activity

Environmental problems are becoming more and more serious and cause social concern.Photocatalytic technology is an effective method to degrade organic pollutants.TiO₂ shows high performance of photocatalytic performance with low cost and strong stability,which attract the researchers attention.TiO₂ has wide bandgap?3.2 eV?,weak absorption and conversion rate of the solar energy especially in the visible light region,therefore,non TiO₂-based photocatalytic materials have attracted much attention.bismuth niobate(Bi₅Nb₃O₁₅)has a layered structure metal oxide composed of alternating Aurivillius phase.And its valence band is composed of Bi 6s orbitals and O 2p orbitals.Bi₅Nb₃O₁₅ has a certain visible light response,but it can only absorb visible light with a wavelength of less than 450nm.This paper worked on Bi₅Nb₃O₁₅ modification and characterization which assisted by various analytical techniques.And the photocatalytic properties of the composite system are studied by degradation of organic pollutants.The specific contents are as follows:1.Study on the design and photocatalytic performance of Pt/Bi₅Nb₃O₁₅/Ti compositesA series of Pt/Bi₅Nb₃O₁₅/Ti composite catalysts with different contents of titanium were prepared by a solvothermal co-precipitation method with isopropanol as solvent.The catalytic performance of each catalyst was evaluated by the catalytic degradation of four brominated bisphenol A?TBBPA?,and the best composite catalyst?BNO/Ti?5%??for TBBPA degradation efficiency was selected.The BNO/Ti?5%?was selected as substrate and a series of Pt/Bi₅Nb₃O₁₅/Ti composite catalysts with different Pt deposition were prepared by means of photodeposition.The amount of Pt load in the catalysts was quantitative analyzed by the ICP-AES;X-ray powder diffraction?XRD?,X ray photoelectron spectroscopy?XPS?,scanning electron microscope?SEM?,transmission electron microscopy?TEM?and ultraviolet visible diffuse reflectance?UV-vis/DRS?were used to characterize the structure,composition and optical absorption properties of Bi₅Nb₃O₁₅/Ti and Pt/Bi₅Nb₃O₁₅/Ti.TBBPA was selected as a target degradation material to evaluate the photoactivity and stability of the photocatalysts.And the possible photocatalytic mechanism of Pt/Bi₅Nb₃O₁₅/Ti is proposed.2.Study on the design and photocatalytic performance of Bi/Bi₅Nb₃O₁₅/Cr₂O₃ compositesA series of Bi/Bi₅Nb₃O₁₅/Cr₂O₃ composite catalysts with different Cr doping content were obtained by one step solvothermal co-precipitation method.Ethylene glycol was chosen as solvent and reducing agent.The photocatalysts were characterized by XRD,XPS,UV-vis/DRS,TEM and so on.The structure,composition and optical absorption properties of the catalysts were analyzed.The catalytic activity was evaluated by degradation of TBBPA and bisphenol A?BPA?to determine the the most appropriate amount of Cr doping.The stability of the system were investigated,and the possible catalytic mechanism of Bi/Bi₅Nb₃O₁₅/Cr₂O₃ was proposed.