Tunable Low-Frequency Microwave Absorption in Flaky Carbonyl Iron via 3D-To-2D ZIF-67 Shell Engineering

) of -54.00 dB at 4.48 GHz. In addition, the combination of first-principles (DFT) and electromagnetic finite element simulation techniques with experimental results has further elucidated the loss mechanism of FCI@ZIF-67. When the shell transitions from a three-dimensional (3D) dodecahedral structure to a two-dimensional (2D) nanosheet, the nanosheet shell effectively releases the π-π* bonds constrained within the 3D framework, significantly enhancing the conduction and dielectric polarization capabilities of the material. This enhancement effect strongly couples with the magnetic loss provided by the FCI core, synergistically optimizing impedance matching and attenuation mechanisms in the low-frequency range. This research provides a clear physical framework for understanding microwave absorption through dimensional control and introduces a low-temperature, frequency-customizable design strategy for advanced absorbers.