Needle‐Like MOF‐74 with Dual‐Defect for Superior Electromagnetic Wave Absorption and Seawater Corrosion Resistance

ABSTRACT Electromagnetic wave absorption (EMWA) materials are essential for mitigating electromagnetic pollution caused by electronic devices. Metal‐organic framework (MOF) derivatives with their tunable composition and architecture hold great promise as high‐performance EMWA candidates. However, achieving ideal EMWA performance typically requires high loadings, which leads to particle agglomeration and significant degradation in both EMWA properties and seawater corrosion resistance when prepared into coatings, which has hindered their practical application. To address these challenges, we demonstrate a dual‐defect engineering strategy to synthesize MOF‐74 derived EMWA material featuring a needle‐like nanoflower architecture. This structural design enhances electromagnetic attenuation due to the introduction of dual‐defect, and significantly improves seawater corrosion resistance. The optimized Ni 0.5 Co 0.5 MOF‐4 sample achieved outstanding EMWA performance, delivering a broad effective absorption bandwidth of 7.84 GHz and a minimum reflection loss of −68.8 dB. Furthermore, by constructing gradient multilayer periodic arrays using Ni 0.5 Co 0.5 MOF‐4, the EAB was extended to 13.32 GHz (covering 4.68–18 GHz). Beyond EMWA performance, the synergistic effects of the C/NiCo alloy and the needle‐like architecture further reinforced the materials seawater corrosion resistance, including the high charge transfer resistance of 293770 Ω. This work opens new pathways for the development of MOF‐based materials that combine superior EMWA with durability in marine environments.