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 (RL_min) 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.