Graphical A bimodal mesoporous Fe 3 O 4 @SiO 2 composite was fabricated through a facile self-assembly route. Unprecedentedly good tunability of the core size (180–1700 nm) and the shell thickness (20–75 nm) has been achieved. The composite exhibits excellent performance in organic pollutant removal through adsorption and photo-Fenton degradation. A facile self-assembly synthetic procedure was exploited to fabricate mesoporous-silica-capped Fe 3 O 4 mesoporous clusters, so-called bimodal mesoporous Fe 3 O 4 @SiO 2 composites. Structural characterization demonstrated that the core of the Fe 3 O 4 clusters is coated with a mesoporous silica shell of uniform size distribution. Moreover, unprecedentedly good tunability of the core size (180–1700 nm) and the shell thickness (20–75 nm) is achievable by changing the synthetic parameters. Application of the composite in the removal of the organic dye methylene blue (MB) from aqueous solution was examined. The composite exhibits excellent adsorption of methylene blue from aqueous solution (33.12 mg g –1 ) within 5 min and is easily regenerated by the photo-Fenton degradation reaction as a result of its high specific surface area, accessible pore channels, and good magnetic separation properties. This novel adsorbent promises extensive application in the practical removal of organic dyes.
Chao Wang,Nankun Chen,Yiyao Xiao,Jiahao He,Rui Han,Ningning Song
Fe 3 O 4 @SiO 2 composites with different morphologies (hollow nanorods , porous nanorods, and flower-like nanoparticles) were constructed using different preparation methods. Considerably enhancement of resonance frequency and permeability beyond Snoek’s limitation were observed in the Fe 3 O 4 @SiO 2 composites with shape anisotropy and porous core-shell nanostructure . The resonance frequency of porous Fe 3 O 4 @SiO 2 nanorods enhanced to 4.21 GHz, which is much higher than the natural resonance frequency of 1.2 GHz for Fe 3 O 4 bulk. The minimum reflection loss (RL min ) of Fe 3 O 4 @SiO 2 porous nanorods reached -59.49 dB at 8.89 GHz, and its effective bandwidth (RL < -10 dB) covered 4.52 GHz at a thickness of 3.18 mm. In addition, the radar scattering cross section (RCS) reduction value reached more than 48 dBm 2 after removing the background. Our study provides insight into the relationship between anisotropy, core-shell structure, morphology of nanoparticles and corresponding microwave performance, and provides a reference scheme for the fabrication of high-performance lightweight microwave absorbing materials.
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