Ni/NiO/SiO2/C nanofibers with strong wideband microwave absorption and robust hydrophobicity

Multifunctional microwave absorbers with robust hydrophobicity and enhanced wave absorption are of great significance for human health and the martial applications. Herein, carbon nanofibers (CNFs) inlaid with Ni/NiO and SiO2 nanoparticles were prepared by electrospinning and in-situ annealing method. Contrast experiments at different annealing temperatures had been conducted to illustrate the formation process and microwave loss mechanism of Ni/NiO/SiO2/CNFs. At the annealing temperature of 550 °C, the optimal reflection loss (RL) of −40.1 dB was reached at 16.6 GHz with a thickness of 2.5 mm, the effective absorption bandwidth (EAB) was 5.2 GHz. The maximum EAB of 8.0 GHz was obtained as the thickness close to 3.0 mm, covering the half of X band and entire Ku band. It was worth mentioning that the introduction of nano SiO2 into the Ni/NiO/CNFs annealed at 550 °C could refine the nanoparticles of Ni, promote the formation of Ni, improve the complex permittivity, and ultimately widen the EAB. Moreover, the contact angle (CA) of the Ni/NiO/SiO2/CNFs membranes annealed at 450, 550, 650 and 750 °C was 154.3°, 138.7°, 142.2° and 144.9°, respectively, illustrating that the products were of robust hydrophobicity. Therefore, the as-prepared NFs are promising in multifunction wave absorbers.