Hydrothermal Sythesis Of ?-Fe₂O₃@TiO₂ Composite Powders And Their Photocatalytic Activities

A simple two-step hydrothermal method has been developed for preparation of ?-Fe2O3@TiO2 composite powders.In first step,(NH4)2TiF6 solution mixed with H3BO3 solution was loaded into teflon autoclave under certain experimental parameters to prepare TiO2 powders with high catalytic activity.In second step,TiO2 powders mixed with FeCl3 solution were transferred into Teflon autoclave under different experimental parameters.(whether join the mineralizer NaCl and ethanol,reaction concentration,reaction temperature,reaction time.)The phase properties,crystallization properties,absorption properties and microstructure of the samples were studied by X-ray powder diffraction(XRD),scanning electron microscopy(SEM)and UV-visible diffuse reflectance spectroscopy(UV-vis DRs).The characterization results showed that the addition of mineralizer NaCl and ethanol can promote the crystallization and increase the particle size of?-Fe2O3.The amounts,the crystallization properties,the particles size of?-Fe2O3 powders are better and ?-Fe2O3@TiO2 composite powders exhibit red shift phenomenon as the decline molar ratio of Ti:Fe.The crystallization properties,the particles size of ?-Fe2O3 powders are better within a certain range increase of reaction temperature,while increasing the reaction temperature will decrease the crystallinity.The amounts of ?-Fe2O3 powders is increased within a certain range incteasing of reaction time,but further increasing the reaction time would not change the amounts and particle size of ?-Fe2O3 powders.The photocatalytic activity of ?-Fe2O3@TiO2 composite powders has been investigated using the ultraviolet light to degrade methylene blue.the results showed that,the ?-Fe2O3@TiO2 composite powders prepared with Ti:Fe=10:1,at 140? for 12h and without any addition of mineralizer NaCl and ethanol showed excellent photocatalytic activity.The degradation rate of methylene blue could reach 83.8 within 180 min.The ability of photocatalytic degradation of ?-Fe2O3@TiO2 composite powders is doubled than that of pure anatase TiO2...