Self-defensive pod-like CoFe@Void@NC@CNFs coatings for naval stealth and corrosion-microbial resistance in harsh marine environments

Previous studies mainly focus on secondary and tertiary treatment to enhance the microwave absorption performance (MAP) and corrosion resistance of dielectric-magnetic multi-component materials, which increases the production cost and difficulty, and leads to the loss of original properties of some components. In this study, a series of core@shell CoFe@Void@N-doped carbon (NC)@carbon nanofibers (CNFs) pod-like nanocomposites (PLNCs) were prepared to elaborately construct via simple electrospinning and MOF-derived strategy. The acquired outcomes demonstrated that the material composition (CoFe@Void@NC regulation) and stratification structure can be reasonably optimized, the designed CoFe@Void@NC@CNFs PLNCs exhibited an effective absorption bandwidth of 8.00 GHz and minimum reflection loss of -55.77 dB, radar cross section value of -64.94 dB·m2, and ultra-wideband of 32.76 GHz in metastructures. Furthermore, the hierarchical pod-like architecture enabled synergistic integration of magnetic-dielectric components and physical barriers across multiple length scales, endowing the CoFe@Void@NC@CNFs with photo-thermal-electric energy recycle and multi-level defense (eg. corrosion resistance and bacteriostatic properties). Especially after 30 days of co-cultivation with bacteria and 7 days of immersion in the simulated marine environment solution, CoFe@Void@NC@CNFs PLNCs still showed excellent comprehensive MAP. Therefore, with the support of multi-level defense functions, core@shell CoFe@Void@NC@CNFs PLNCs with performance-durability is expected to be used in complex and variable marine environments.