Hydrothemal Preparation And Photocatalytic Properities Of Iron Oxide And Core-Shell Structure

TiO₂ exhibits low photocatalytic efficiency because of its wide band gap.Besides,a powdery photocatalyst is difficult to recover the photocatalytic reaction is generally carried out in suspension,which greatly limits the application of TiO₂ in the degradation of pollutants.To improve the photocatalytic activity of TiO₂ photocatalyst and achieve recycling reuse,this topic uses original two steps hydrothermal method to prepare Fe_xO_y@TiO₂ core-shell magnetic materials.With laser particle size analyzer,XRD,SEM,TEM and EDS means,the dispersion,particle size and coating of core Fe₃O₄,α-Fe₂O₃ and core-shell Fe_xO_y@TiO₂ were characterized.The photocatalytic performance evaluation of Fe_xO_y@TiO₂ was analyzed by the degradation of methyl orange experimen,and the magnetic of core-shell materials was also detected.Fe₂O₃ and Fe₃O₄ with good dispersion were firstly prepared by using FeCl3·6H₂O as iron source through hydrothermal reaction.Then,Fe₃O₄ and Fe₂O₃ were added to the TiO₂ precursor solution and by hydrothermal method to gain magnetic Fe₃O₄@TiO₂ and Fe₂O₃@TiO₂.The preparation method of core material,dispersion and the effect of Fe/Ti the molar ratio on photocatalytic properties of core-shell materials were analyzed.Furthermore,by usin g K₃[Fe（CN）₆]as iron source and adjusting the pH of the precursor solution,the morphology changes of α-Fe₂O₃ during the hydrothermal reaction were observed.The results showed that:the optimal conditions for preparing core Fe₃O₄ particles are hydrothermal temperature of 180℃ and hydrothermal time of 20h;the size of Fe₂O₃ prepared by hydrothermal process after calcining step is larger than that was prepared by hydrothermal processes,and the morphology rules;by adjusting the pH value,the morphology of α-Fe₂O₃ sequential changes from three-dimensional lotus-shaped stone,fishbone,fishbone-like,semi-snowflake-shaped,two-dimensional dendritic,to snow flake-shaped leaves;by adding 3 ml,mmol/L of CTAB,the dispersion of Fe_xO_y is significantly improved;when the molar ratio of Fe/Ti is 1:30,Fe_xO_y@TiO₂ typical core-shell structure was obtained,for the characteristics of high surface activity of Fe₃O₄,photocatalytic efficiency of core-shell Fe₃O₄@TiO₂ is up to 73.7%.and Fe₂O₃@TiO₂ exhibits medium thickness of the shell,the contact surface of Fe₂O₃ and TiO₂ forms heterojunction,making the photocatalytic efficiency reach to 81.1%.In addition,Due to the presence of magnetic core Fe₃O₄ and superparamagnetic core α-Fe₂O₃,magnetic core-shell materials are prepared when the shell thickness is moderate（The molar ratio of Fe/Ti is 1:10,1:30）.