Production of hierarchical porous carbon nanosheets from cheap petroleum asphalt toward lightweight and high-performance electromagnetic wave absorbents

Developing efficient and cheap electromagnetic wave absorption (EWA) materials is highly desirable in modern information society. Herein, based on the abundant and low-cost petroleum asphalt, hierarchical porous carbon nanosheets (PCNs) have been rationally fabricated via one-step carbonization process by using water-removable NaCl templates. The NaCl can provide crystal planes for the growth of graphitized carbon layers, and promote the formation of interconnected porous architectures. The porous nanosheets structures realize the multiple reflections and scattering in the void space. The presence of dipole polarization and interfacial polarization in PCNs facilitates the dielectric loss. Remarkably, the EWA performance of optimized PCNs with a low filler content of 20 wt% reaches a strong reflection loss of −53.7 dB and a broad absorption bandwidth of 5.3 GHz at a thin thickness of 1.8 mm. This encouraging performance considerably outperforms most of reported dielectric materials, which also meets the demands of thin, light weight, strong and broad features for new-type EWA materials. Therefore, our strategy may open up new avenues for development of promising EWA materials and realizing the high value-added utilization of petroleum asphalt by considering the facile process and low production cost.