PVP-assisted transformation of ZIF-67 into cobalt layered double hydroxide/carbon fiber as electromagnetic wave absorber

A high efficiency and ultra-light electromagnetic wave (EW) absorber is proposed without precedent. A series of hierarchical short carbon fibers (SCFs) based composites with in-situ grown cobalt layered double hydroxides (Co-LDHs) can be successfully synthesized via a simple PVP-assisted solvothermal method. The synthesized hierarchical structure is composed of 1D SCFs skeleton, 3D hydrangea-like Co-LDHs-1 and 1D rod-like Co-LDHs-2. Notably, ultralight (5 wt% in paraffin matrix), ultrathin (2.1 mm) and ultrawide (6.5 GHz) features are achieved in our composites by simply tuning the doping amount of PVP. The mechanism is explained by the tunable attenuation constant and impedance matching, that is, Co-LDHs-1 and Co-LDHs-2 with different conductivities and morphologies are coordinated to optimize the excessively high complex permittivity of SCFs. This contribution will shed the light on design of LDHs-based materials for light-weight, tuning, and high efficiency EW absorbers.