“Host-Guest” crystalline Mo/Co-framework induced phase-conversion of MoCx in carbon hybrids for regulating absorption of electromagnetic wave

Unveiling the structural design and synthesizing mechanism of the metallic crystalline precursors is of great significance for constructing hetero-interfaces and enhancing the EW attenuation in electromagnetic wave absorbing materials (EWAMs). Herein, two diverse crystalline Mo-species incorporated metal-organic framework precursors were designed for studying the phase conversion during the high-temperature treatment and evaluating their electromagnetic wave (EW) absorbing mechanism. The MoO 4 as the node on the framework and the Mo 12 O 40 cluster as guest in the framework derived β -Mo 2 C and η -MoC in MoC x /Co@NC hybrids, respectively. The EW absorbing performance results indicated a superior RL min of −47.72 dB at 11.76 GHz at the thickness of 2.0 mm and a wide effective absorption bandwidth (EAB) of 4.58 GHz (7.44–12.02 GHz) covering the whole X-band at the thickness of 2.5 mm for η -MoC/Co@NC. The “Host-Guest” precursor induced the uniformly distributed η -MoC and metallic Co nanoparticles in the N-doped carbon matrix, generating abundant 3d/4d hetero-interfaces and intense synergistic interaction. The crucial role of thermal stability of the crystalline framework and phase conversion among multi-components were investigated, which lighten the structural design of the high-performance EWAMs in the future. A brilliant structural design strategy of Host-Guest structural precursor (Mo-POM@Co-ZIF) was proved for obtaining a high-efficient EWAM ( η -MoC/Co@NC). The highly porous structure and uniformly distributed hetero-interfaces enhanced the electromagnetic attenuation and impedance matching, displaying superior SRL of −176.39 and −159.07 at 1.5 and 2.0 mm, and wide EAB of 4.58 GHz (7.44–12.02 GHz) which covered the whole X-band at 2.5 mm.