Abstract
Owing to the unique order mesopores, mesoporous SBA-15 could be used as the carrier of the magnetic nanoparticles. The magnetic nanoparticles in the frame and the mesopores lead to the exchange-coupling interaction or other interactions, which could improve the magnetic properties of SBA-15 nanocomposites. Mesoporous Fe/SBA-15 had been prepared via in situ anchoring Fe2O3into the frame and the micropores of SBA-15 using the sol-gel and hydrothermal processes. Co3O4nanoparticles had been impregnated into the mesopores of Fe/SBA-15 to form mesoporous Fe/SBA-15-Co3O4nanocomposites. XRD, HRTEM, VSM, and N2physisorption isotherms were used to characterize the mesostructure and magnetic properties of the SBA-15 nanocomposites, and all results indicated that the Fe2O3nanoparticles presented into the frame and micropores, while the Co3O4nanoparticles existed inside the mesopores of Fe/SBA-15. Furthermore, the magnetic properties of SBA-15 could be conveniently adjusted by the Fe2O3and Co3O4magnetic nanoparticles. Fe/SBA-15 exhibited ferromagnetic properties, while the impregnation of Co3O4nanoparticles greatly improved the coercivity with a value of 1424.6 Oe, which was much higher than that of Fe/SBA-15.
Highlights
SBA-15, a type of mesoporous zeolite, features large uniform mesopores arranged into a two-dimensional (2D) hexagonal structure with the micropores (1∼2 nm) in the frame [1, 2]
The microstructure and magnetic properties of the obtained SBA-15 samples were analyzed by X-Ray powder diffraction (XRD), High resolution transmission electron microscopy (HRTEM), Vibrating Sample Magnetometer (VSM), and N2 physisorption isotherms, and the results were discussed in detail
Based on the previous work with small-angle XRD [26] and N2 adsorption-desorption isotherms below, α-Fe2O3 nanoparticles should exist in the frame of SBA-15
Summary
SBA-15, a type of mesoporous zeolite, features large uniform mesopores arranged into a two-dimensional (2D) hexagonal structure with the micropores (1∼2 nm) in the frame [1, 2]. After a variety of surface modifications, such as the introduction of guest molecules through coating or incorporations and surface or mesopore grafting of metal atoms, the obtained new materials were suitable for many new applications, such as catalysis, separation, and drug delivery. Yiu et al [20] synthesized novel magnetic Fe metal-silica (Fe/SBA-15) and magnetite-silica (Fe3O4/SBA-15) nanocomposites with high Fe contents through temperature programmed reduction, which exhibited superparamagnetic properties with a total magnetization value of 17 emu·g−1. Zhu et al [10] prepared a novel magnetic and temperature-responsive drug delivery system based on poly(N-isopropylacrylamide) (PNIPAM) modified SBA-15 containing magnetic γ-Fe2O3 nanoparticles. Separable Fe/SBA-15 nanocomposites were synthesized by Lin et al through selective deposition of Fe2O3 nanoparticles into the micropores of SBA-15, and Fe2O3 nanoparticles embedded in the micropores exhibited superparamagnetic properties [22]. The microstructure and magnetic properties of the obtained SBA-15 samples were analyzed by XRD, HRTEM, VSM, and N2 physisorption isotherms, and the results were discussed in detail
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