Dual-effect confinement engineering reconciles electromagnetic wave absorption with marine corrosion protection

The simultaneous achievement of efficient electromagnetic wave absorption (EWA) and long-term corrosion protection in complex marine environments remains challenging due to inherent structural conflicts between porous electromagnetic absorbers and compact anticorrosion coatings. Herein, a multi-scale spatial assembly strategy is proposed to construct a three-dimensional hollow spherical carbon foam (HSCF) decorated with layered double hydroxide (LDH) nanosheets via a three-stage process (protonation, morphological reconstruction, and confined assembly) to realize a dual-effect confinement mechanism. From the perspective of electromagnetic energy confinement, enhanced synergistic effects among the architectural units induce intensive scattering and polarization loss, achieving a minimum reflection loss of -68.11 dB and a maximum effective absorption bandwidth of 7.40 GHz. Electromagnetic simulations further confirm the outstanding radar stealth capabilities across a wide range of incident angles. From the perspective of corrosive media confinement, the tortuous HSCF skeleton physically retards the diffusion of corrosive species, while the anchored LDH nanosheets actively capture chloride ions via anion exchange. Consequently, the resulting HSCF@LDH/epoxy (EP) composite coating exhibits excellent corrosion resistance, featuring a significantly enhanced corrosion potential and reduced current density compared with the pure EP coating. Overall, this dual-effect confinement mechanism enabled by the multi-scale spatial assembly strategy establishes a new structural paradigm for the next generation of multifunctional EWA materials for extreme operational environments.