The synthesis of porous carbon material derived from coal liquefied residue and its electromagnetic wave absorption

To solve the problem of electromagnetic radiation pollution, it is necessary to develop an economic and environmentally friendly way of producing efficient electromagnetic wave absorbing materials. Carbon-based materials have attracted much attention but finding suitable precursors and ways of producing defined pore structures are still challenges. This work reported a facile method to produce porous carbon by using coal liquefaction oil residue as carbon source. The produced porous skeletons should be attributed to the generated Na2CO3 templates and CO2 gas during the thermal decomposition process of NaHCO3 templates. It is found that changing the pore structure not only adjusts the impedance matching of the material but also increases the length of the electromagnetic wave transmission path and increases dielectric loss. With the combined effect of multiple electromagnetic loss mechanisms, the material has excellent electromagnetic wave absorption. Specifically, with a filler loading of only 10% and a thickness of 2.03 mm, the obtained carbon material has a reflection loss value of −60.28 dB and an effective absorption bandwidth of 5.36 GHz. This work provides a new approach to developing high-performance carbon-based electromagnetic wave absorbing materials and also offers a new idea for the high value-added use of coal liquefaction oil residue products.