Simultaneous optimization of conduction and polarization losses in CNT@NiCo compounds for superior electromagnetic wave absorption

Polarization and conduction losses are the two most crucial dielectric loss mechanisms for carbon-based composites, but their synergistic effects in different frequency bands need to be further revealed. More importantly, for polarization and conduction losses, the strengthening of one party always comes at the expense of the other, which inevitably limits the overall performance of the absorbers. Herein, we have developed a composite of CNT and NiCo hybrid particles via a scalable wet chemical process and annealing method. Through the adjustment of the precursor and the annealing temperature, the conduction and polarization losses of the composite are optimized simultaneously. The optimized samples achieved the full absorption of the X and Ku bands under conditions of low filling rate and thin thickness. Further theoretical and experimental studies have revealed conduction loss and polarization loss laws at different frequency ranges. The synergistic effect of conductive loss and magnetic loss in the low-frequency region ensures that the sample exhibits high microwave dissipation performance. However, in the medium and high-frequency part, the magnetic loss can be almost ignored and the timely replenishment of polarization loss keeps the wave-absorbing performance at a high level. The excellent multi-band absorption characteristics make the as-obtained absorbers meet the needs of future applications.