Direct Incorporation of Magnetic Constituents within Ordered Mesoporous Carbon−Silica Nanocomposites for Highly Efficient Electromagnetic Wave Absorbers

Abstract

Low-density ordered mesoporous carbon−silica nanocomposites with different Fe contents have been prepared by a facile solvent-evaporation-induced self-assembly approach. Magnetic metal nanocrystallines are highly dispersed in the composites due to in situ carbothermal reduction. The optimal reflection loss calculated from the measured permittivity and permeability is −34.4 dB at 13.1 GHz. Moreover, the electromagnetic wave absorption less than −10 dB is found to exceed 5.0 GHz for an absorber thickness of 2 mm. The microwave enhancement absorption of the mesoporous C−SiO2−Fe nanocomposites is contributed to the better match between dielectric loss and magnetic loss, which originates from the high absorption by the incorporation of magnetic species as well as the multiple reflections by the ordered mesoporous structure. The mesoporous C−SiO2−Fe nanocomposites also exhibit a lower infrared emissivity in the wavelength from 8 to 14 μm than that of Fe-free powder.

Remarkable improvement in microwave absorption by cloaking a micro-scaled tetrapod hollow with helical carbon nanofibers

“…20 In fact, the microwave absorption properties are influenced by the interfacial interactions of novel structures. Bi et al reported that the decoration of bowl-like hollow Fe 3 O 4 spheres on both sides of the r-GO nanosheets enhanced greatly the dielectric loss of the materials, resulting in a wider absorption band and a larger reflection loss in the frequency range of 2-18 GHz.…”

Mesoporous Silica Functionalized by Cyclam–Metal Groups: Spectroscopic Studies and Numerical Modeling

“…magneto-optical switchers and bi-sensors [1][2][3], drug delivery controllers [4][5][6] or catalytic agents [7,8]. Thus, the considered materials are the subject of broad field of investigations [9][10][11][12] since the functionalities can be tuned by changing the nature of the functional groups such as nanoparticles [13], magnetic clusters [14], organic or organometallic molecules [15].…”

Microwave absorption properties of MWCNT-SiC composites synthesized via a low temperature induced reaction

“…As referred in literature, porous structure may exhibit good microwave absorbing properties. 5,6,[16][17][18] When microwave transmits into the porous spheres, multiple reflections and scattering will occur, leading to gradual dissipation of EM energy. The bulk quantities of defects, such as stacking faults, grain boundaries and interfaces, which can give rise to space charge polarization and relaxation, are also favorable to improving microwave absorption.…”

“…Among the candidates for EM wave absorbers, carbon and magnetic particle doped carbon, such as CNTs, 1,2 Fe encapsulated CNTs, 3 FeCo-filled CNTs, 4 porous carbon/Co composite, 5 and ordered mesoporous C-Fe-SiO 2 composites, 6 have been reported to exhibit outstanding EM absorbing properties. As an alternative candidate for microwave absorbing materials, SiC possesses high chemical stability, superior mechanical strength and hardness, good fracture toughness and abrasive properties at high temperatures.…”