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In terms of microwave absorption, dielectric performance acts vital but has negative characteristics in attenuation and impedance matching. In this study, ZnO/nanoporous carbon (NPC)/reduced graphene oxide (RGO) materials have been fabricated through a simple and valid hydrothermal method derived from Zn metal–organic frameworks (MOFs). By changing the molar ratio of the precursors, the permittivity of the ZnO/NPC/RGO can be calculated, and the greatest balance between energy conservation and impedance matching eventually emerged with the addition of 4 mL of GO. It could be found that, at 14 GHz, a thin sample consisting of 40 wt % ZnO/NPC/RGO in the wax matrix exhibited minimum reflection loss of −50.5 dB with a thickness of 2.4 mm, and with a thickness of 2.6 mm, the effective microwave absorption bandwidth coverage is from 9.6 to 17 GHz. It is worth mentioning that we have also interpreted the relationships between the highest reflection loss values and matching thicknesses. This work not only proposes that ZnO/NPC/RGO samples are able to function as a perfect absorbent with broad frequency bandwidth and strong absorption but also provides better candidates in designing other lightweight microwave absorbents.

In this study, we report a porous-carbon-based Mo2C nanocomposite (NCs) as the microwave absorber via typical carbothermal reduction using metal-organic frameworks (MOFs) and polyoxometalates (POMs) as the precursors, which have been rarely applied in electromagnetic (EM) wave absorption areas. The elaborately designed NCs not only bring about good impedance matching, but also possess strong dissipation ability due to the large surface areas and porous features. Thanks to the material characteristics as well as structural advantages, the as-prepared Mo2C/C NCs with 20 wt% sample loading exhibit remarkable microwave absorbing performance. The minimum RL value reaches -49.19 dB at matching thickness of 2.6 mm, and the best effective bandwidth (RL < -10 dB) of 4.56 GHz at 1.70 mm was also achieved. Moreover, the NCs overcome the intrinsic drawback of traditional carbon materials, that is, centralized effective absorption always occurred at high frequency (>10 GHz) and the minimum RL value of the NCs shifted to 9.04 GHz. Clearly, in this study, we not only developed the Mo2C NC as the new light absorber, but also paved the way to synthesize other available transition metal carbides using MOFs and POMs.

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