Ordered mesoporous carbon with hierarchical pore structure for high-efficiency electromagnetic wave absorber under thin matching thickness

An enormous challenge exists in the development of low-density and efficient microwave absorbers with thin matching thickness. Carbon materials with hierarchical porosity are regarded as potential candidates for practical applications of microwave absorption (MA) materials on account of their rich pore structure which facilitates the entry and attenuation of electromagnetic waves. Herein, ordered mesoporous carbon with hierarchical interconnected network structure (NOMC) was prepared through a self-assembly method and calcination treatment. It was found that by adjusting the annealing temperature, the hierarchical porous structure, the carbon defect, the dielectric loss property and the MA property could be tuned. Thanks to the balance between sufficient hierarchical porous structure, outstanding impedance matching condition and multiple loss modes, NOMC displays outstanding ability to dissipate electromagnetic waves at a very thin absorbing coating thickness. Notably, as-prepared NOMC-700 displays an outstanding MA property, whose minimum reflection loss (RL_min) value reaches −27.5 dB at 16.72 GHz and the effective absorption bandwidth (EAB) achieves 3.2 GHz (14.8–18 GHz) under 1.5 mm absorbing coatings. Hence, the satisfying design in porous microstructure can pave the way for efficient MA materials with thin matching thickness.