The heterostructure and hierarchical morphology of carbonaceous absorbents play an important role in the construction of high-performance electromagnetic wave absorbing materials. Herein, novel micron-scale hard carbon particles with morphology heterogeneity were developed as lightweight superior electromagnetic wave absorbents via a facile and ecofriendly process. The as-prepared hard carbon particle composed of pseudographite and a highly disordered region shows a unique heterostructure. Concurrently, constructing a multilevel geometric shape and size can cause a decrease of the percolation threshold and an excellent balance between polarization and conduction loss, which enhances the electromagnetic wave absorption significantly. The composites (thickness d = 2.36 mm) filled with morphology-heterogeneity hard carbon particles (15 wt %) achieve an excellent electromagnetic wave absorption with a minimum reflection loss of -78.0 dB at 10.2 GHz and effective absorption bandwidth (<-10 dB) of 3.1 GHz (8.8-11.9 GHz). Compared to the traditional carbonaceous absorbents with complex microstructures and/or multiple chemical components, this work presents a feasible idea for the development of an efficient carbonaceous absorbent to realize practical applications.
Keywords: electromagnetic wave absorption; hard carbon particles; micron scale; morphology heterogeneity; percolation threshold.