Hyper-Cross-Linked Polymers-Derived Porous Tubular Carbon Nanofibers@TiO₂ toward a Wide-Band and Lightweight Microwave Absorbent at a Low Loading Content

An enormous challenge exists in the achievement of one-dimensional (1D) dielectric carbon composite high-performance microwave absorbents at a low filling ratio. Porous/core–shell dual microstructures have been considered as the potential candidate for designing remarkable microwave absorbers with strong absorption and wide band. Herein, novel multiple-structured tubular carbon nanofibers@TiO2 (TCNFs@TiO2) hybrids were constructed via the sequential steps of hydrolysis and pyrolysis. The dielectric properties of the as-prepared composites can be tuned by adjusting the relative content of the TiO2 shell and carbonaceous temperature to enhance the impedance matching behavior. Notably, the minimum reflection loss (RLmin) value reaches up to −61.2 dB with an effective absorption bandwidth (EAB) of 3.2 GHz at 3 mm, and the EAB can cover 5.3 GHz with a thickness of merely 2 mm when 1.3 mL of tetrabutyl titanate (TBT) and 700 °C pyrolysis temperature are optimized, respectively. Delightedly, the mixing ratio is only 10 wt %, outperforming that of the most-related composites. The heterogeneous interfaces in TCNFs–TiO2 are beneficial for the interfacial polarization relaxation. Besides, the hybrids are enriched with numerous pores to favor the lightweight absorbers. The desirable design in the microstructure can provide a promising route in wide-band and lightweight microwave absorbents.