Heterostructure design of carbon fiber@graphene@layered double hydroxides synergistic microstructure for lightweight and flexible microwave absorption

At present, there is an urgent need to develop lightweight and flexible high-efficiency microwave absorbing materials. Herein, reduced graphene oxide (RGO) was successfully attached to cotton-derived flexible carbon fiber (CF) by electrostatic self-assembly, and then two-dimensional layered double hydroxides (LDH) were closely arranged on the surface of CF/RGO to form a unique core-sheath structure. The carbonized CF contains a large number of heteroatoms, which enhance the dielectric loss caused by polarization. In addition, RGO acts as an intermediate layer to facilitate the conductive loss of the CF/RGO/LDH composite. Moreover, the voids created by the stacked LDH induce the scattering and reflection of electromagnetic waves and optimize the impedance characteristics. As a result, the ternary core-sheath CF/RGO/LDH composite shows the optimal reflection loss value of -60.9 dB at 10.3 GHz with a thickness of 2.5 mm and efficient absorption bandwidth value of 6.1 GHz when the filling ratio is only 20 wt%. This work provides an efficient route for the design and preparation of lightweight and flexible microwave absorbing materials.