Green synthesis and tunable microwave absorption properties of core-shell structure SiC@Ni/C(N) nanocomposites

SiC-based materials exhibit excellent and tunable microwave absorption properties due to their unique combination of lightweight, high-temperature stability, oxidation resistance, and robust mechanical strength. Herein, we have successfully prepared the N-doped C embedded with Ni nanoparticles (NPs) co-matrix shell-modified SiC nanocomposites (SiC@Ni/C(N)) in this work. The synthesis method involved adopting a mussel-inspired Ni2+mediated dopamine self-polymerization reaction and heat treatment process subsequently. The microwave absorption capacity of as-prepared SiC@Ni/C(N) nanocomposites can be tailored by changing the content of Ni NPs derived from additions of nickel salt in the synthesis process, which makes them acquire superior microwave absorption performance. When the mass ratio of SiC NPs to nickel ion was 5:2, the as-prepared SiC@Ni/C(N) nanocomposites exhibited strong microwave absorption with an optimum reflection loss of -45.63 dB at a frequency of 8.99 GHz with a thickness of 2.67 mm. The absorption bandwidth of SiC@Ni/C(N) nanocomposites below -20 dB is 11.41 GHz, corresponding to 3.33-14.74 GHz, with a thickness range of 1.66-6.00 mm. The superior microwave absorption of the SiC@Ni/C(N) nanocomposites stems from their intense multiple interfacial polarization, abundant defects dipole polarization, improved conduction loss, and appropriate magnetic losses, which results in the balance of impedance matching and attenuation ability, thus acquiring excellent microwave capacity.