MoS₂ nanoparticle/activated carbon composite as a dual-band material for absorbing microwaves

In the search for novel high-performance microwave (MW) absorbers, MoS₂ has shown promise as a MW-absorbing material, but its poor impedance matching limits its applications. Herein, a facile hydrothermal method was used to produce a composite consisting of activated carbon (AC) derived from waste biomass and in situ-grown MoS₂ nanoparticles. Its microwave absorption properties were examined in the 2-18 GHz frequency range, and FESEM and HRTEM images confirmed the formation of MoS₂ nanoparticles on the AC. The maximum reflection loss (RL_max) for the MoS₂/AC composite was -31.8 dB (@16.72 GHz) at 20 wt% filler loading. At 50 wt% filler loading, the MoS₂/AC (MAC50) composite exhibited unique dual-band absorption characteristics in the C and K_u bands. An effective absorption bandwidth (RL < -10 dB) of 10.4 GHz (3-5.2 GHz, 9.8-18 GHz) was achieved at various thicknesses that covered the entire K_u band. Therefore, a sole dielectric absorber can easily be tuned to absorb MWs at multiple frequency ranges. The large surface area and conduction losses of AC combined with the superior dielectric loss properties of MoS₂ resulted in improved impedance matching and attenuation ability of the MoS₂/AC composite. Thus, MoS₂/AC is a promising low-cost dielectric absorber for MW absorption applications.