Search

Electron/phonon heat co-transfer, dielectric/magnetic dual loss, and 2D interlinked frameworks codetermine the ultrawide absorption bands, high thermal conductivity, and excellent electrical insulation of CF/M/C (M = Co, Ni, or Fe/Fe 3 O 4) 2D interlinked frameworks. [Display omitted] • A facile soaking-annealing strategy for CF/M/C (M = Co, Ni, Fe/Fe 3 O 4) 2DIFs. • Precisely modulating the interfaces, porosity, and defects. • Optimizing the thermal, electrical, and EMW absorbing properties. • Revealing the synergistic enhancement mechanism. Reasonable design of protective multifunctional materials is highly required for the safety protection of devices/personnel from electromagnetic radiation and heat damage in the 5G/6G era. Herein, a simple soaking-annealing route was adopted to carbonize filter paper into 2D interlinked carbon fiber frameworks inlaid with magnetic nanoparticles, and the products were referred to as CF/M/C 2DIFs (M = Co, Ni, or Fe/Fe 3 O 4). The concentration and type of metal ions as well as the annealing temperature of the CF/M/C 2DIFs were controlled to precisely modulate their composition, porosity, and defects. Results show that the CF/Co/C 2DIFs produced under T a = 600 °C and [Co2+] = 0.45 mol/L exhibit high thermal conductivity (2.931 ∼ 3.167 W/m·K) at small loads (10 ∼ 30 wt%) owing to not merely the presence of 2D interlinked path for electron/phonon heat co-transfer but the reasonable control of interface/defects for weakening phonon/electron defect/interface scattering. Also, the CF/Co/C 2DIFs can attenuate microwaves over a broad frequency range via dielectric/magnetic dual loss and 2DIFs, which boosts their loss ability and matching performance. The excellent performance in both heat dissipation and EM wave absorption proves that the CF/M/C 2DIFs can be a promising candidate for next-generation electronic packaging materials in heat management, military, and aerospace fields. [ABSTRACT FROM AUTHOR]

To develop light-weight polymer-based multifunctional materials with outstanding electromagnetic wave absorbing/shielding properties and high thermal conductivity, 2D interlinked carbon fiber networks (2D ICFNs) were synthesized via direct pyrolysis of filter papers at 600–900 °C. The pyrolysis temperature (T p) was controlled to modulate the porosity, defects, and the resulting properties of 2D ICFNs. Owing to the co-manipulation of defects and porosity, the 2D ICFNs formed under T p = 900 °C exhibit a larger EABW max /d (3.57 GHz/mm) and stronger absorption (−44.66 dB) at a lower load (15%) compared to most other carbon fiber (CF)-based materials. Their shielding effectiveness is beyond 20 dB over 2.0–18.0 GHz with a maximal value of 76.2 dB at 18 GHz, surpassing the minimum requirement (20 dB) for practical applications. Besides, the 2D ICFNs with moderate porosity and high graphitization bear a larger thermal conductivity (2.69–2.93 W/mK) at a lower filling ratio (20 wt%) in comparison to the majority of previously reported materials. This is primarily due to the shortened phonon/electron transfer paths, decreased phonon-interface/-defect scattering, and continuous paths for thermal transmission in the 2D ICFNs. Overall, it is believed that the 2D ICFNs can be one of the most promising multifunctional fillers for EM absorption applications. Briefs2D interlinked carbon fiber networks were synthesized via direct pyrolysis of filter papers, exhibiting defect/porosity-co-manipulating high thermal conductivity, good electric insulation, and prominent EMI shielding/absorption. [Display omitted] • Direct pyrolysis of filter papers for 2D interlinked carbon fiber networks. • Controlling pyrolysis temperature to modulate the porosity and defects. • Optimizing the thermal, electrical, and EMW absorbing/shielding properties. • Defects and porosity co-manipulating the prominent properties. [ABSTRACT FROM AUTHOR]

The saucer-shaped CNF/Fe x O y wafers were synthesized by a sol–gel and annealing route, exhibiting a high thermal conductivity, wide absorption band, prominent EMI shielding effectiveness and excellent electrical insulation. [Display omitted] • A sol–gel and annealing strategy for saucer-shaped CNF/Fe x O y wafers. • Precisely regulating the texture, composition and defects of CNF/Fe x O y wafers. • Optimizing the thermal conductivity and EMW absorbing/shielding properties. • Revealing the synergistic enhancement mechanism. The property incompatibility among heat conduction, electromagnetic wave (EMW) absorption/shielding, and electrical insulation has restricted the synchronous enhancement and application of polymer-based composites. Herein, we first synthesized porous 3D interlinked C nanofiber/Fe x O y (CNF/Fe x O y) wafers for significantly enhanced properties by a simple sol–gel and annealing route. The texture, composition, defects and the resulting properties can conveniently be manipulated via altering Fe3+ concentration and annealing temperature. The CNF/Fe x O y wafers exhibit a high heat conductivity (3.22 W/mK) at a low loading (30 wt%) thanks to the shorter continuous thermal transfer paths and the increased phonon mean free path and thermal capacity of phonons per volume. Moreover, CNF/Fe x O y wafers possess a wide absorption band (9.36 GHz), prominent EMI shielding effectiveness (SE T ≥ 20 dB over C, X, and Ku bands), excellent electrical insulation (σ = 0.00991 S/m), and enhanced mechanical/hydrophobicity properties, surpassing most reported fillers. These enhancements could be explained by the fact that the cooperative action of porous structures, defects, and magnetic/dielectric Fe x O y hinder electron migration and improve the impedance matching and multiple-scattering of materials. The silicone composites supported by 3D interlinked CNF/Fe x O y wafers have great potential as a filler with high-performance EMI shielding/absorption and thermal control in next-generation flexible electronics. [ABSTRACT FROM AUTHOR]