Rice husk-based hierarchically porous carbon and magnetic particles composites for highly efficient electromagnetic wave attenuation

Abstract

For RHPC/Fe, RL of −21.8 dB can be achieved with the absorption bandwidth (RL ≤ −10 dB, ABW) of 5.6 GHz at a thickness of 1.4 mm, while for RHPC/Co, RL of −40.1 dB can be achieved with ABW of 2.7 GHz at a thickness of 1.8 mm.

Broadening Electromagnetic Absorption Bandwidth: Design from Microscopic Dielectric‐Magnetic Coupled Absorbers to Macroscopic Patterns

“…Meanwhile, the comparison with some typical carbon-based microwave absorption composites shows that the artificial meta-structure designs possess greater opportunities for obtaining effective absorption over more electromagnetic bands (Figure 12b). [1][2][3][4][5][6][7] Implication of the results also suggests that the strategy based on absorption structure design appears to be increasing attractive in developing advanced absorption materials for their capability in integrating advantages from both materials and structures. …”

“…[4] Currently, Fangand co-workers have prepared hierarchically porous carbon/magnetic particle hybrid from rice husk, and the as-fabricated Co/carbon and Fe/carbon composites have presented effective absorption bandwidth of 9-12 GHz and 12-16 GHz, respectively. [1] According to the development in the absorber material design, it is apparent that most of the efforts have been massively focused on profiling the nanoscale structure and morphology coupled with tuning interfacial physical properties of the heteromaterials. Specifically, the traditional design for uniform bulk materials (layers) is usually established on the generation quarter-wavelength resonance in the materials of certain thickness ( Figure 1a).…”

“…[1][2][3][4][5][6][7][8][9][10][11][12] With progressive achievement in nanomaterials and nanotechnology, tremendous prototypes of materials with remarkable variety of morphologies have been well documented for the substantial impacts of nanostructures and chemical components on the electromagnetic waves. In particular, carbon materials including carbon fibers, carbon nanotubes, and graphene have been widely explored for fabricating lightweight fillers that are effective in microwave absorption composites, with receiving the greatest attention among recent electromagnetic sensitive materials.…”

Electromagnetic Wave Absorption Performance of Carbonized Rice Husk Obtained at Various Temperatures

“…The disclosure of unnecessary or excessive electromagnetic (EM) wave emission are expected due to the extensive utilization of devices/applications associated with EM wave especially at GHz frequency ranges (G‐, X‐, Ku‐band, etc.) in electronic fields, wireless communication, and radar . Furthermore, this might leads to device malfunction, disturbance of electronic system, harm the environment, or affect the health of human beings, which has attracted the urgency to develop EM wave absorbing materials .…”

“…Furthermore, this might leads to device malfunction, disturbance of electronic system, harm the environment, or affect the health of human beings, which has attracted the urgency to develop EM wave absorbing materials . Effective EM wave absorber materials will be able to dissipate EM wave energy into heat or different forms of energy and in result the EM wave cannot be reflected or permeated through the absorber materials, in addition to other advantageous properties such as lightweight, tunable absorbing ranges, and multifunctionality . The incident wave through the absorber materials undergoes the following phenomenon: penetration, reflection, and absorption, for the energy loss process …”