Heterointerface-engineered SnO2@SnO nanoparticle@foamed C composites for prominent microwave absorption and thermal conduction performance

Abstract

The development of multifunctional materials with wide-band microwave absorption properties (MWAPs), high thermal conductivity (TC), and excellent electrical isolation is rather challenging due to the performance incompatibility. To resolve this challenge, SnO2@SnO nanoparticle(NP)@foamed C composites are synthesized as an electrically insulated filler with low loads, excellent MWAPs, and high TC via a facile salt-template-assisted freeze-drying-annealing route. By controlling the annealing temperature (Ta) and the amount of SnCl2·2H2O (n), their heterointerfaces, textures, and defects were finely modulated. Our results show that the SnO2@SnO NP@foamed C composites have a large TC (3.48 W/(m·K); 1.5 wt% load), a minimal reflection loss (RLmin) of −40.75 dB, and an effective absorption bandwidth (EAB) of 6.88 GHz at a low load of 25 wt%. The composites exhibit an 8.0 % increase in TC, a 9.4 % increase in EAB, and an 11.0 % increase in RLmin compared with pure foamed C. Besides, the mechanism of dielectric loss and thermal transfer at the atomic level was revealed by the calculations of the density of states (DOS) and the phonon density of states (PDOS). The boosted MWAPs could be ascribed to the breakdown of local microstructural symmetry and the formation of extra electric dipoles at the interfaces of SnO/C, SnO/SnO2, and SnO2/C. The improved TC mainly results from the combined effect of the low-energy phonons from SnOx and the high-energy phonons from C. This study provides theoretical guidance for designing integrated materials with effective microwave absorption and thermal conduction in the electronic industry.