Partic. vol. 10 no. 6 pp. 751-758 (December 2012)
doi: 10.1016/j.partic.2012.04.003

Synthesis of mesoporous γ-AlOOH@Fe₃O₄ magnetic nanomicrospheres

Yuanyuan Zheng, Shengfu Ji^*, Hongfei Liu, Ming Li, Hao Yang

jisf@mail.buct.edu.cn

Abstract

Mesoporous γ-AlOOH@Fe₃O₄ magnetic nanomicrospheres were synthesized using superparamagnetic Fe₃O₄ nanoparticles as the core and aluminum isopropoxide (AIP) as the aluminum source. The obtained magnetic nanomicrospheres were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2 adsorption–desorption and vibrating sample magnetometry (VSM). The effects of preparation parameters such as hydrolysis time of AIP, concentration of AIP and coating layer number on microspheres were investigated. The results indicated that the mesoporous γ-AlOOH@Fe₃O₄ magnetic nanomicrospheres consisted of a mesoporous γ-AlOOH shell and a Fe₃O₄ magnetic core. The diameter of γ-AlOOH@Fe₃O₄ nanomicrospheres was about 200 nm, the thickness of mesoporous γ-AlOOH shell was about 5 nm and the average pore size was 3.8 nm. The thickness of the mesoporous γ-AlOOH shell could be controlled via layer-by-layer coating times. The formation mechanism of the mesoporous γ-AlOOH shell involved a “chemisorption–hydrolysis” process.

Graphical abstract

Keywords

Magnetic nanomicrospheres; Fe₃O₄; γ-AlOOH shell; Mesoporous; Hydrolysis