Cavity-modulated visualization of dual magnetic coupling behavior for multifunctional Co/DMAOP composites

The demand of microwave-absorbing materials for the marine environment requires the multifunctional characteristic, including microwave absorption, corrosion protection, and antimicrobial. However, achieving these properties without compromising on the microwave-absorbing performance remains a significant challenge. Here, we present a self-sacrificial template strategy to synthesize Co-metal–organic framework (MOF)-74 nanorods, achieving synergistic anticorrosion and antibacterial effects by the introduction of dimethyl octadecyl (3-trimethoxysilylpropyl) ammonium chloride (DMAOP). Our findings show that by adjusting the cavity shape, internal and exterior double-coupling behaviors may occur simultaneously, greatly increasing the synthetic composites’ capacity for magnetic loss. As a result, the Co/DMAOP-120 with 100.00 % cavity structure has an ideal reflection loss (RL) value of up to − 68.05 dB and an effective absorption bandwidth (EAB) of 4.88 GHz at a thickness of 3 mm. This material also shows significant corrosion resistance and a bacterial inhibition rate against Staphylococcus aureus (S. aureus) of 93.89 %. The maximum radar scattering cross section (RCS) of Co/DMAOP-120 under far-field conditions is significantly reduced compared to that of a perfect electrical conductor (PEC), further validating the highly efficient wave-absorbing capability of Co/DMAOP-120 in real-world environments. The new magnetic loss mechanism offers fresh recommendations for designing the microstructure of materials that waves in absorb several ways.