Co-Ni Electromagnetic Coupling in Hollow Mo2C/NC Sphere for Enhancing Electromagnetic Wave Absorbing Performance†

For enhancing the electromagnetic wave (EW) attenuation and adsorption, rational constructing and homogeneously distributing bimetallic electromagnetic coupling units in hollow structure is an effective way, but hard to achieve. Herein, a CoNi-doped hybrid zeolite imidazole framework was synthesized as precursor, which was further converted into a hollow CoNi-bimetallic doped molybdenum carbide sphere (H-CoNi@MoC/NC) through a two-step etching and calcination strategy. At the loading amount of 15 wt%, a strong absorption of minimum reflection loss (RLmin) of -60.05 dB at 7.2 GHz with the thickness of 3.1 mm and a wide effective adsorption bandwidth (EAB) of 3.52 GHz at the thickness of 2.5 mm were achieved, which was far beyond the reported MoC-based metallic hybrids. The crucial synergistic Co-Ni electromagnetic coupling effect in the composite was characterized, not only enhancing the dipolar/interfacial polarization, but also promoting the impedance matching, displaying the optimized EW absorbing performance.