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

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.