Conductive MOFs with tailored polarization loss for broadband absorption at ultrathin thickness

Conductive metal-organic frameworks (MOFs) have emerged as promising electromagnetic wave absorption (EMWA) properties materials due to their tunable dielectric properties and straightforward synthesis. Nevertheless, achieving broad effective absorption bandwidth (EAB) at ultrathin thickness remains a significant challenge. Herein, a series of rod-haped bimetallic CuM-HHTP (M = Mn, Co, Ni, and Zn) were synthesized via a hydrothermal approach. Remarkably, all fabricated samples demonstrated wide EAB values at ultrathin thickness. The EAB performance was found to correlate positively with the electron transfer capability of metal ions, following the order: CuNi > CuCo > CuZn > CuMn. This trend can be attributed to subtle variations in charge carrier concentrations and dipole moment modifications induced by the coordination of heterogeneous metal ions to hydroxyl groups, which arise from the coordination tendency and bond strength of the heterobimetallic binding to the ligands. The EAB value of CuNi-HHTP reached up to 7.12 GHz (10.88–18.00 GHz) at a matching thickness of only 1.78 mm. The outstanding EMWA performance was originated from optimized impedance matching, synergistic dipole and defect polarization, interface polarization, and conductive loss. Additionally, radar cross-section simulation confirmed the material's practical applicability in EMWA. This study presents a novel strategy for designing high-performance bimetallic conductive MOFs absorbers with tailored electromagnetic properties.