Constructing a tunable heterogeneous interface in bimetallic metal-organic frameworks derived porous carbon for excellent microwave absorption performance

Designing pure carbonaceous microwave absorbers with strong absorption capability and broad effective absorption bandwidth (EAB) is still a challenge for efficient microwave absorption. Here, a kind of bimetallic metal-organic frameworks derived porous amorphous carbon particle with hollow graphene spheres confined in it (HGS@PAC), was prepared by the controlled annealing process. The thickness of hollow graphene spheres could be tuned from 9 graphene layers to 24 graphene layers by adjusting the annealing time, and thereby tuning their dielectric properties. The minimum RC of the optimized HGS@PAC reaches −56 dB at 3.5 GHz with a thickness of 6.75 mm, indicating its strong microwave absorption performance. In addition, the widest EAB reaches 5.6 GHz (12.4–18 GHz) with a thickness of only 1.85 mm. It is important to highlight that the EAB can cover the whole measured bandwidth (2–18 GHz) with the sample thickness ranging from 1.85 mm to 10 mm. The enhanced microwave attenuation ability can be ascribed to the enhanced interfacial polarization, dipole polarization, and conductive loss, resulting from the designed unique architectures.