Multi-Scale Synergistic Regulation Strategy to Develop Mesoporous Carbon Hollow Nanospheres/Bean-Shaped Nanofibers for Corrosion-Resistant, Flexible, and Lightweight Microwave Absorbers

Addressing the critical demand for next-generation lightweight, high-efficiency microwave absorbers, this paper proposes a "micro-meso-macro" multi-scale synergistic regulation strategy. Specifically, core@shell mesoporous carbon hollow nanospheres (HNSs)@carbon bean-shaped nanofibers (BNFs) are designed and fabricated efficiently using SiO₂/carbon solid nanospheres as precursor through a continuous electrostatic spinning, heat treatment, carbonization, and hydrofluoric (HF) etching. The acquired results suggest that the regulation of carbonization temperature greatly improves the graphitized degree of mesoporous carbon HNSs@carbon BNFs, which significantly enhances the values of complex permittivity. Furthermore, the introduction of a controllable number of mesoporous carbon HNSs at the mesoscale significantly increases the specific surface area and promotes the interfacial polarization effects. The macroscopic 3-dimensional continuous conductive network constructed via electrospinning further enhances electron transport capability and conductive loss efficiency. Benefiting from the excellent collaborative design between multi-scale structure and composition, the optimized mesoporous carbon HNSs@carbon BNFs display excellent microwave absorption properties with a minimum reflection loss (RL_min) of -61.03 dB at 2.42 mm and an effective absorption bandwidth (EAB) of 6.2 GHz at 2.18 mm. Meanwhile, the acquired mesoporous carbon HNSs@carbon BNFs also present excellent corrosion resistance, hydrophobicity, flexibility, and lightweightness. Generally, the finding proposes a simple route for the production of novel core@shell C@C nanocomposites, which makes the best of multi-scale construction strategy to develop lightweight multifunctional microwave absorbers.