Pre‐Calcination‐Governed Spatial Architecture Engineering of MOF‐Derived Magnetic Carbon Nanohybrids for Effective Microwave Absorption
Na Chen, Bing‐Bing Han, Xiaoning Song, Boyou Hou, Kang‐Jun Wang, Xiao‐Guang San, Ye‐Tang PanABSTRACT
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.