Abstract: Metal-organic frameworks (MOFs) have been widely applied in the field of electromagnetic wave absorption (EMWA) on account of unique morphology, simple fabrication, and ultra-high porosity. Nevertheless, the facile method of protecting its structure from being destroyed remains challenging. Herein, we proposed a hydrothermal method combined with a carbonization strategy to construct the 0D/1D/2D Fe₃C@NC@Mo₂C/Fe₃C composites. Owing to the incorporation of polydopamine (PDA), the carbon shell formed during high-temperature carbonization effectively protected the original MIL-88A rod-like structure, and the 2D Mo₂C nano-sheets and 1D Fe₃C nanoparticles were coated on the surface of 1D Fe₃C nanorods. With the increase in carbonization temperature, the EMWA properties of the composites presented a trend of first increasing and then decreasing. Impressively, the composites (at 750 °C) exhibited praiseworthy EMWA performances with a minimum reflection loss value of -43.70 dB at 8.00 GHz, alongside a maximum effective absorption bandwidth of 6.08 GHz (11.20-17.28 GHz). Density functional theory calculations confirmed the distinctive charge distribution resulting from the heterointerface, which is beneficial to the polarization loss and conductive loss. As a result, the outstanding EMWA performance was credited to the distinctive hierarchical structure, appropriate impedance matching, numerous heterogeneous interfaces, and magnetic loss. Moreover, Radar cross-section calculations indicated that the composites have tremendous potential for practical application. Thus, this work may pave new avenues for designing high-performance and structure-controllable absorbing materials.

Key words: Microstructure design, Hierarchical structure, Microstructure protection, Electromagnetic wave absorption