Pre‐Calcination‐Governed Spatial Architecture Engineering of MOF‐Derived Magnetic Carbon Nanohybrids for Effective Microwave Absorption

ABSTRACT Precisely steering the spatial distribution of functional units in MOF‐derived carbon‐based hybrids remains a formidable challenge for microwave absorption. Here we reveal that pre‐calcination can govern the intermediate chemistry and final spatial architectures of an identical ZIF‐8@PBA precursor, yielding two structurally distinct nanohybrids (Fe 3 C−N−C and Fe 3 C−N−CNTs). Pre‐calcination at 200°C preserves the ZIF‐8@PBA framework to spatially confine Fe species enabling uniform Fe 3 C dispersion during subsequent pyrolysis, forming Fe 3 C−N−C; whereas pre‐calcination at 400°C decomposes the framework into Fe 3 O 4 /ZnO intermediates that convert to surface‐exposed Fe 3 C with localized enrichment, catalyzing carbon nanotubes (CNTs) growth to yield Fe 3 C−N−CNTs. The Fe 3 C−N−C architecture simultaneously enhances polarization relaxation, ferromagnetic resonance, and impedance matching, thus delivering a minimum reflection loss (RL min ) of −73.60 dB and an ultrawide effective absorption bandwidth (EAB) of 9.29 GHz at 3.32 mm, superior to its pervious cournterparts. In comparison, The Fe 3 C−N−CNTs shifts to a dielectric‐dominated regime, yielding an RL min of −65.71 dB, and an EAB of 7.79 GHz at 2.04 mm. These findings reveal that nanoscale spatial arrangements govern the attenuation–impedance balance in microwave absorbers. This work establishes a new mechanistic paradigm for designing high‐performance microwave absorbers and functional materials by tailoring spatial architectures.