Hierarchical structure and compositional engineering in MOF-derived carbon nanocomposites via polyoxometalate-mediated coordination competition for enhanced electromagnetic wave absorption

Abstract

Hierarchical structure engineering and multicomponent design are pivotal for developing high-performance electromagnetic wave (EMW) absorbers, however, conventional synthetic strategies still face significant challenges in simultaneously achieving precise control over multi-component, microstructural construction and size regulation. Herein, an asymmetric hierarchical metal–organic framework (MOF)-derived nanoporous carbon (NPC) composite is fabricated via a polyoxometalate (POM)-mediated coordination competition strategy. Tungsten-based POM (W-POM, Na₃ [PW₁₂O₄₀]) acts as a dynamic structural modulator during Cu-MOF assembly. By competitively coordinating with Cu(II) ions against organic ligands, the W-POM precisely regulates Cu(II) ion release kinetics and nucleation, enabling concurrent control over precursor size (100–400 nm), morphology (evolving from octahedra to aggregated polyhedra), and composition. Subsequent pyrolysis transforms these W-POM@Cu-MOF precursors into a hierarchical architecture featuring asymmetrically grown Cu nanosheets on porous carbon matrix, alongside embedded Cu nanoparticles and W-POM-derived Na₂WO₄ heterostructures (Cu/W/NPC). This unique anisotropic configuration synergistically enhances microwave attenuation, where Cu nanosheets and porous matrix prolong propagation paths and induce multi-scattering, while the uniformly dispersed Na₂WO₄ and heterogeneous interfaces significantly boost interfacial polarization and dipole polarization. Consequently, the optimized nanocomposite exhibits superior EMW absorption performance, achieving a minimum reflection loss (RL_min) of −61.4 dB and a broad effective absorption bandwidth (EAB) of 6.64 GHz. COMSOL simulations quantitatively confirm the abundant interfaces and porous structures synergize polarization dissipation and multi-reflection mechanisms, optimizing impedance matching. Radar cross-section (RCS) simulations further demonstrate significant attenuation (29.84 dB m²), highlighting practical stealth utility. This work establishes a versatile POM-mediated coordination competition paradigm for architecturally and compositionally tailored MOF-derived advanced EMW absorbers.