Incorporation of FexOy nanoparticles into 3D interlinked porous carbon nanofiber networks to synergistically enhance the electrical insulation, electromagnetic wave absorbing/shielding performance and thermal conductivity

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/FexOy (CNF/FexOy) 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/FexOy 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/FexOy wafers possess a wide absorption band (9.36 GHz), prominent EMI shielding effectiveness (SET & GE; 20 dB over C, X, and Ku bands), excellent electrical insulation (& sigma; = 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 FexOy hinder electron migration and improve the impedance matching and multiple-scattering of materials. The silicone composites supported by 3D interlinked CNF/FexOy wafers have great potential as a filler with highperformance EMI shielding/absorption and thermal control in next-generation flexible electronics.

Automated summary

Porous 3D interlinked C nanofiber/FexOy (CNF/FexOy) wafers were synthesized and showed significantly enhanced properties. The properties of the wafers can be manipulated by adjusting Fe3+ concentration and annealing temperature. The CNF/FexOy wafers exhibit high heat conductivity, wide absorption band, excellent EMI shielding effectiveness, and enhanced mechanical/hydrophobicity properties, making them promising fillers for high-performance EMI shielding/absorption and thermal control in flexible electronics.