Bimetallic zeolitic imidazolate frameworks-derived porous carbon-based materials with efficient synergistic microwave absorption properties: the role of calcining temperature

Abstract

The composites of metal Co embedded in porous and N-doped graphitized carbon matrix (Co@pNGC) have been successfully synthesized by thermal decomposition of the bimetallic zeolitic imidazolate frameworks (bi-ZIFs) at different temperatures. The experimental results show that the calcination temperature played a decisive role on the graphitization, specific surface area, pore structure and electromagnetic wave (EM) absorption properties of Co@pNGC. The composites, Co@pNGC-600 and Co@pNGC-700 obtained at 600 °C and 700 °C, respectively, exhibit an outstanding EM wave absorption performance, which attributes to the synergistic effects of dielectric and magnetic loss, porous structure and multicomponent interfaces. Specifically, the optimal reflection loss of Co@pNGC-600 is −50.7 dB at 11.3 GHz and the widest effective absorption bandwidth (<−10 dB) could reach upto 5.5 GHz (12.3–17.8 GHz). The minimum thickness corresponding to the effective absorption is only 1.2 mm for Co@pNGC-700. Hence, these obtained porous carbon composites are promising microwave absorbing materials due to their lightweight, thin thickness, low filling, broad bandwidth, and strong absorption.