Synthesis And Photocatalytic Performance Of ?-Fe₂O₃ And Its Composites

?-Fe₂O₃ is a typical n-type semiconductor material,which has the characteristics of narrow band gap?2.0-2.2 e V?,chemical stability,low cost,natural abundance and environmental friendliness.It is an ideal semiconductor material for photocatalytic degradation of organic pollutants and water decomposition for hydrogen production,which has attracted extensive attention and research of many researchers.This thesis mainly studies the preparation,characterization and photocatalytic performance of?-Fe₂O₃ and its composites.The main contents are as follows:?1?A simple solvothermal method process for preparation of?-Fe₂O₃ nanometer photocatalyst with good dispersion,uniform morphology and uniform size was developed,and the growth mechanism of?-Fe₂O₃ graded nanophotocatalyst was proposed.Finally,using methylene blue as a simulated pollutant,the visible light photocatalytic performance of the hierarchical structure?-Fe₂O₃ nanophotocatalyst was studied.The results showed that under the optimal photocatalytic reaction conditions,the photocatalytic degradation rate of the hierarchical structure?-Fe₂O₃ nanophotocatalyst to methylene blue was 87%,and the synthesized photocatalyst has superior photocatalytic activity.?2?A two-step solvothermal method process for preparation of?-Fe₂O₃@TiO₂ composite photocatalyst was developed by the?-Fe₂O₃ powder synthesized under the specific conditions of the previous step was added to the mixture of tetrabutyltitanate?TBT?and ethanol,and the?-Fe₂O₃@TiO₂ core-shell structure composite photocatalyst was successfully prepared.In addition,the composite photocatalyst was characterize by SEM,TEM,XRD,XPS,DRS,BET and other characterization methods in detail.Finally,the prepared?-Fe₂O₃@TiO₂ composite photocatalyst was tested for photocatalytic degradation of methylene blue.The degradation rate of methylene blue by composite photocatalyst under visible light irradiation was 96%,the?-Fe₂O₃@TiO₂ composites have been proved to show superior photocatalytic activity to the pure TiO₂ and?-Fe₂O₃ nanoparticles.?3?According to the test results of the photocatalytic degradation of methylene blue by?-Fe₂O₃@TiO₂ core-shell structure composite photocatalyst,the enhancement mechanism of the photocatalytic performance of the composite photocatalyst was preliminarily discussed.The results show that the proper energy level difference between the narrow band gap?-Fe₂O₃ and the wide band gap TiO₂ leads to the decrease of the band gap energy of the composite,and the reduced band gap can effectively improve the utilization of visible light.At the same time,the good energy band matching of?-Fe₂O₃/TiO₂ heterojunction and core-shell structure promotes the effective separation of photogenerated carriers,thus improving the photocatalytic activity of the composite...