The efficient absorption of electromagnetic waves by tunable N-doped multi-cavity mesoporous carbon microspheres

Porous carbon microspheres have been acknowledged as one kind of effective microwave absorption materials, but simple- and volume-produce still remains a big challenge. In this work, we developed a facile template-free and one-step approach to construct unique multi-cavity mesoporous carbon microspheres for enhanced microwave absorption. The production of multi-cavity pores is induced by the selective etching effect of acetone to the phenolic resin oligomers, which is much simplified and easy operated compared with traditional soft/hard template method. Further, the quantity of mesopores can be effectively regulated through controlling the addition of acetone. It is demonstrated the porous structure plays a significant role on dielectric and absorption capability. The carbon microsphere with appropriate mesoporous structure (60 mL of acetone etching) presents attractive absorption performance with strong reflection loss (RL) intensity of −44.5 dB and wide effective absorption bandwidth (EAB) of 4.72 GHz at only thickness of 1.6 mm. The relationship between porous structure and performance and absorption mechanism are also investigated in detail. This work may pave a new way for punching pores in carbon microspheres and implement corresponding potential application in solving microwave interference issue.