Excellent self-cleaning, ultrawideband absorption, and rapid heat dissipation of magnetic hybrid foams from a facile one-step annealing route

Abstract

To solve the problems of severe electromagnetic (EM) pollution and thermal exhaustion in modern electronics, this study prepared flexible magnetic hybrid foams (MHFs)/silicone films as advanced multifunctional materials with excellent thermal conduction and microwave absorption. A general one-step PVP-assisted annealing strategy is developed to selectively synthesize the MHFs (Fe/Fe₃C/C, Fe_3−yNi_yO₄/Fe_1−xNi_x/C, and Ni/C), and their formation is mainly attributed to the self-assembly induced by PVP and gas bubbles in situ generated by nitrates. Their texture, composition, and defects can be modulated by altering the salt type, [Ni²⁺], and annealing temperature, which consequently co-determine their overall performance. Experimental results show that the MHFs produced under [Ni²⁺] = 0 and 73.2 mol% exhibit a wide absorbing band (EABW/d = 5.16–5.17 GHz mm⁻¹; 2.2–2.4 mm) and strong absorption (RL_min = −48.72 dB) due to enhanced matching, attenuation, and multiple scattering caused by a 3D interconnected porous structure and a magnetic/dielectric dual-loss heterostructure. Besides, the MHFs possess a large thermal conductivity (3.26–3.47 W m⁻¹ K⁻¹) under a small load of 10–30 wt% owing to the synergy of the decreased phonon defect/interface scattering, electron/phonon co-transmission, and a 3D interlinked continuous pathway. Furthermore, the MHFs have strong hydrophobicity (95.71°), a low rolling angle (≤6°), and tunable magnetic and electrical conductivity. Overall, these results suggest that the MHFs are highly quantified for applications in self-cleaning, EM interference, and thermal management. Meanwhile, the strategy employed in this study may be of great assistance to the design and fabrication of multifunctional MHFs with exceptional thermal conduction and EM wave absorption.