Stabilization of nanosized MgFe₂O₄ nanoparticles in phenylene-bridged KIT-6-type ordered mesoporous organosilica (PMO)

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Timm, Jana ; Blößer, André ; Zhang, Siyuan ; Scheu, Christina ; Marschall, Roland:
Stabilization of nanosized MgFe₂O₄ nanoparticles in phenylene-bridged KIT-6-type ordered mesoporous organosilica (PMO).
In: Microporous and Mesoporous Materials. Bd. 293 (2020) . - 109783.
ISSN 1873-3093
DOI: https://doi.org/10.1016/j.micromeso.2019.109783

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Abstract

The unique combination of two functional materials, namely the earth-abundant spinel magnesioferrite (MgFe2O4) and mesoporous phenylene-bridged KIT-6-type organosilica, was developed. The mesoporous organosilica acts as host matrix for the nanosized MgFe2O4 particles which leads to better dispersibility and increased stability towards acids. Additionally, the mesoporous host is a very good material to generate a toolbox towards applicable materials due to flexible functionalization. Nanosized, monodisperse MgFe2O4 crystallites were synthesized via a facile microwave assisted non-aqueous reaction path. Afterwards, the particles were embedded in phenylene-bridged periodic mesoporous organosilica with 3D cubic pore arrangement (KIT-6-type PMO) generating a new kind of mesoporous inorganic-organic hybrid material (MgFe2O4@phe-PMO). The MgFe2O4@phe-PMO exhibits the characteristics of both components: A high specific surface area of 1164 m2g-1 with clearly defined and highly ordered micro- and mesopores (1.5 and 6.8 nm), and the broad absorption of visible and UV light due to the phenylene bridging units in the PMO and the MgFe2O4 particles. The presence of MgFe2O4 nanoparticles in the PMO matrix is proven by UV/Vis spectroscopy, powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM). Selected area electron diffraction (SAED) and Scanning TEM in atomic resolution was chosen to demonstrate the crystallinity and phase purity of MgFe2O4 particles in the hybrid material. An additional focus was laid on calcination of the MgFe2O4/PMO hybrids to remove template molecules, while preventing rearrangement or shrinkage of the pore system and to promote further crystallization of the MgFe2O4 nanoparticles.