Constructing interpenetrating structured NiCoO/HCNT composites with heterogeneous interfaces as low-thickness microwave absorber.

Low matching thickness, broad effective absorption bandwidth (EAB, RL < -10 dB) and excellent reflection loss (RL) are desirable properties for the advanced microwave absorption materials (MAMs). We synthesized novel interpenetrating structured rod-like nickel cobaltite (NiCoO)/helical carbon nanotubes (HCNT) composites using the facile hydrothermal technique and heat-treatment process. Owing to the optimum structural design and electromagnetic parameter regulation, the NiCoO/HCNT composites displayed outstanding microwave absorption (MA) across regions of low thickness. When the thickness was only 1.35 mm, the optimized RL and EAB reached -55.9 dB and 4.8 GHz (13.2-18.0 GHz), respectively. Furthermore, the EAB was 10 GHz as the corresponding thickness was regulated with 1.35-2.10 mm, covering both X and the Ku bands. Multiple reflection and scattering, natural resonance, eddy current loss, strong conduction loss, interface polarization, cross-poalarization, and dipolar polarization can be considered to improve MA. Our study proposes a simple approach of synthesizing low-thickness MAMs based on NiCoO and HCNT.