Atomic-scale gradual architecture in conductive metal-organic frameworks for microwave absorption

In classical transmission-line theory, the attenuation constant (α) and wave impedance (η) are mutually constraining, making the simultaneous optimization of impedance matching and efficient attenuation the central challenge in electromagnetic wave absorption (EWA) design. To address this, we proposed an atomic-level gradual architecture by using a Zn-HHTP (hexahydroxytriphenylene) conductive metal-organic frameworks (cMOFs) template. Through precise temporal addition of metal ions and ligands, we created a gradual compositional change from core to surface within a single crystal particle (Zn²⁺-rich→Cu²⁺-rich→Co²⁺-rich). This gradual architecture breaks the α-η limitation via a synergistic cascade. First, fine-tuning the interlayer spacing of the 2D cMOFs nanosheets from core to surface achieves a gradual dielectric real part, creating a smooth, inwardly decreasing wave impedance profile that minimizes the reflection of electromagnetic waves and promotes volume dissipation. Second, the gradual architecture forms a continuous band offset, promoting charge separation and migration. A multi-metal self-polarization effect further increases dipole polarization. This establishes an atomic-scale 'trap-and-dissipate' cascade for EWA. Consequently, by only manipulating spatial ion arrangement, the gradual cMOFs achieve a 155 % increase in attenuation capability over the homogeneous architecture. This work introduces a spatially gradual architecture that simultaneously optimizes α-η, providing a scalable pathway toward next-generation EWA materials.