单分散α-Fe_2O_3纳米结构空心亚微球的制备及表征

采用一种新的溶液生长法结合多步包覆法在自制的不同粒径SiO2单分散亚微球表面包覆不同厚度的β-FeOOH涂层,得到单分散β-FeOOH/SiO2核壳结构亚微球.实验结果表明,SiO2核心颗粒尺寸对表面涂层的形态和包覆均匀性有很大影响.当SiO2核心颗粒的平均粒径为250 nm左右时,β-FeOOH表面涂层均匀,颗粒间团聚较少,一次包覆后涂层厚度约为35 nm.涂层中β-FeOOH纳米棒的尺寸随着所选SiO2核心颗粒粒径的增大而相应增大.经多次包覆能够显著提高涂层的厚度,3次包覆后β-FeOOH表面涂层厚约100 nm.β-FeOOH/SiO2核壳结构亚微球与质量分数5%的NaOH溶液反应后,于600℃焙烧2 h得到了单分散α-Fe2O3空心微球.单分散α-Fe2O3空心亚微球表层是由α-Fe2O3纳米棒搭建而成的三维网络结构,α-Fe2O3纳米棒的尺寸与核壳结构中β-FeOOH纳米棒的尺寸基本一致.

Preparation and Characterization of Monodisperse α-Fe2O3 Nanostructured Hollow Submicrosphere

The home-made monodisperse SiO2 submicrospheres were coated with β-FeOOH by a new solution growth method. The size of SiO2 submicrospheres had great influence on the microstructures of β-FeOOH coatings. When the average diameter of the submicrospheres was 250 nm, the β-FeOOH coating was uniform and the average thickness of β-FeOOH coatings was about 35 nm after the first cycle of coating. The thickness of β-FeOOH coatings increased greatly with multistep coating. After three cycles of coating, the thickness of β-FeOOH coatings increased to about 100 nm. The core-shell composites were immersed in NaOH solution(5%, mass fraction) at 40 ℃ for 24 h to remove the silica cores and then calcined at 600 ℃ for 24 h to prepare the monodisperse α-Fe2O3 hollow submicrospheres. The α-Fe2O3 shells in the hollow submicrospheres were constructed with α-Fe2O3 nanorods interconnected.