“Host-Guest” crystalline Mo/Co-framework induced phase-conversion of MoC_x 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 MoO₄ as the node on the framework and the Mo₁₂O₄₀ cluster as guest in the framework derived β-Mo₂C 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.