Selective tailoring of covalent bonds on graphitized hollow carbon spheres towards controllable porous structure and wideband electromagnetic absorption

Recently, the exploration of a new strategy to create pores on carbon frameworks has received great interest. Herein, the selectively tailoring of the covalent bonding method has been shown to be one of the effective methods to generate pores based on graphitic hollow carbon frameworks (HGC). The mechanism of porous structure formation is due to directional clipping of sp(2) C-C and C=O covalent bonds into C-O bonds. Due to the effectively ability for selective tailoring of covalent bonds, the resulting porous HGC has dielectric transition behavior from conductive loss to dipole polarization dependent type, which is greatly beneficial to electromagnetic absorption. The results show that the porous HGC developed by this method has exceptionally EM absorption capacity, and the maximum qualified absorption bandwidth (f(E)) is 7.7 GHz at the thickness of 2.2 mm. Therefore, this work opens up a potential method for the design and synthesis of high-performance EM absorbers. (C) 2020 Elsevier Ltd. All rights reserved.