The Study Of Synthesis,Catalytic Performance Of Bismuth Ferrite Based Composite Photocatalyst

Photocatalysis technology has advantages such as low energy consumption,low cost and no secondary pollution,which attract a lot of researchers' attention.However,most current photocatalysts can only absorb high-frequency photon energy in ultra-violet region but cannot effectively utilize low-frequency photon energy in visible region and the photogenerated carriers are easily recombined during the photocatalytic reaction.Therefore,it is actually meaningful to extend the visible reacting region of photocatalyst and restrain the combination of photogenerated carriers,which improves the photocatalytic performance of materials.BiFeO₃ is a perovskite semi-conductor material with narrow bandgap.It is widely studied due to its excellent visible photocatalytic activity.In the paper,pure-phase BiFeO₃ semi-conductor material was synthesized by one-step hydrothermal method.Ag/AgCl/BiFeO₃ and Ag/RGO/BiFeO₃ composite photocatalyst were synthesized using BiFeO₃ as the master catalyst.The degrading effects of two composite photocatalysts on waste water are studied and their photocatalytic dynamic models to rhodamine B are created.The main contents and conclusions of the research are shown as below:?1?In 160? temperature,PEG-20000 as the dispersant,hydrothermally reacts for 10 hours to make BiFeO₃.Analysis methods such as XRD,SEM,EDS,UV-Vis DRS were applied to characterize the phase,structure,morphology,light absorption,etc.The results have shown that BiFeO₃ made under alkline conditions has good crystallinity,a uniform microstructure of about 35 ?m and strong light absorption.?2?BiFeO₃,RGO and AgNO₃ as the raw materials,Ag/RGO/BiFeO₃ photocatalyst has been made with hydrothermal methods.BiFeO₃ and AgCl as the raw materials Ag/AgCl/BiFeO₃ photocatalyst has been synthesized when exposed to light.The resulthas shown that when exposed to light,the photogenerated carriers of Ag/AgCl/BiFeO₃ have two migrations methods.When added less AgCl,AgCl displays indirect bandgap and photocatalytically reacts on the surface of AgCl and BiFeO₃.Compared to the former,its reacting active sites increase.It is found that in the photocatalysis of the latter material,the photoelectric conversion efficiency greatly improves,the combination of photogenerated electron-hole pairs decrease and the utilization efficiency of carriers improves.?3?After studying the performance of Ag/RGO/BiFeO₃ and Ag/AgCl/BiFeO₃ photocatalysts photocatalyzing and degrading dye waste water and phenolic waste water,the results have shown that Ag/RGO/BiFeO₃ and Ag/AgCl/BiFeO₃ have good photocatalytic activity to dye waste water and phenolic waste water.The active free radical experiments have shown that hydroxyl free radicals,superoxide free radicals and photogenerated holes contribute to the photocatalytic reaction,among which hydroxyl free radicals are most active.?4?The Langmuir-based modeling equations are created where the surface of Ag/RGO/BiFeO₃,Ag/AgCl/BiFeO₃ absorb organic pollutants,respectively are1/Q_e=10.2429/ce+0.42384 and 1/Q_e=10.5017/ce+0.33483.The Langmuir-Hinshewood based dynamics equations are created where Ag/RGO/BiFeO₃ and Ag/AgCl/BiFeO₃ photocatalytically degrading organic pollutants,respectively are 1/r₀=32.5c₀+8.08 and1/r₀=27.59/c₀+1.048.