Synthesis of Porous 3D Fe/C Composites from Waste Wood with Tunable and Excellent Electromagnetic Wave Absorption Performance

Abstract

Here, we synthesized Fe/C composites with different crystal structures (Fe 3 O 4 @C, Fe 3 O 4 /Fe@C, or Fe 3 C@C) by carbonizing iron(III) 2,4-pentanedionate (Fe(acac) 3 ) pre-enriched forestry waste wood at different pyrolysis temperatures from 400 to 1000 °C. The obtained samples are porous 3D (three-dimensional) biochars inlaid with varied Fe phases. The corresponding EMW absorbing properties are proved to be dependent on the pyrolysis temperature, as well as the resulting crystal structures and graphitization degrees. Among them, Fe 3 C@C obtained at 1000 °C possesses excellent EMW absorbing properties with a minimum RL value of −57.64 dB at 6.92 GHz and a wide response bandwidth of 5.00 GHz covering 6.36−11.36 GHz. This good performance is due to continuous substances of Fe 3 C covering the inner surface of the conductive biochars, permitting the optimal impedance matching along with the strongest dielectric loss and optimal magnetic loss. Moreover, more defects are generated at 1000 °C which act as the dipole center and produce dipole relaxation polarization. The dipole relaxation is proved to be positive for improving the EMW absorbing performance together with the interface polarization between C−Fe 3 C.

Lotus Leaf-Derived Gradient Hierarchical Porous C/MoS2 Morphology Genetic Composites with Wideband and Tunable Electromagnetic Absorption Performance

“…In the end, we compared the |RL|, effective bandwidth versus thickness for the MGM-based absorption materials published in the recently literature, as shown in Fig. 11 (details in Table S2) [49][50][51][52][53][54][55][56][57][58]. It clearly suggests that the outstanding EMW absorption performance of the lotus leaf-derived GHPCM…”

Rational Construction of Hierarchically Porous Fe–Co/N-Doped Carbon/rGO Composites for Broadband Microwave Absorption

“…According to the microwave absorption mechanism, when absorbers have magnetic loss, dielectric loss, and impedance match, more microwaves can enter the interior of the materials and be converted into other forms of energy and dissipated [8,9]. In past decades, many efforts were devoted to researching composites for enhancing microwave absorption, such as (Fe, Ni, Co)/C [10][11][12], (Fe, Ni, Co)/rGO [13][14][15], MFe 2 O 4 /rGO (M = Fe, Ni, Co) [16][17][18][19], MFe 2 O 4 / CNTs [20][21][22], and NiO/SiO 2 /Fe 3 O 4 /rGO [23,24]. However, these materials have the shortcoming of narrow absorption bands, which seriously hinders their practical applications.…”

Lightweight and Construable Magnetic Wood for Electromagnetic Interference Shielding

“…[ 4 ] Among them, iron oxide, a typical magneto‐dielectric material with both magnetic loss and dielectric loss, is one of the most attractive microwave‐absorbing materials. [ 5 ] However, limitations on the direct application of magneto‐dielectric materials or conventional metal‐based materials in EMI shielding fields still exist due to high density, high material thickness, fabrication difficulty, and unsatisfactory shielding effectiveness. [ 6,7 ] Thus, the development of ideal EMI shielding materials that are lightweight, construable, and thermally stable and have strong absorption capacities is essential and urgently needed.…”