Construction of shell-like carbon superstructures through anisotropically oriented self-assembly for distinct electromagnetic wave absorption

Carbon materials have been widely recognized as one of the important candidates for superior microwave absorbers, but further enhancement of their properties (especially for a wide bandwidth) is still a great challenge. In this study, we developed a simple soft template-carbonization method to construct special shell-like carbon superstructures used for significant enhancement of microwave absorption. Through an interfacial self-assembly process using ribose as the carbon precursor, a copolymer as the soft template, and sulfuric acid as the catalyst, three microstructurally distinct carbon materials: sphere-like, rod-like, and shell-like carbon superstructures can be prepared by simply adjusting the amount of the structure-guiding agent PSSMA. Owing to the unique semi-hollow cavity structure of the shell-like carbon superstructures, the conductive loss and polarization loss are synergistically regulated, accompanied by the synergistic improvement of their impedance matching and loss capability. As a result, the shell-like carbon superstructures hold excellent electromagnetic wave absorption capability, in which the reflection loss (RL) can reach ?49.14 dB and the effective absorption bandwidth (EAB) can reach 8.24 GHz. The relationships between the morphological structure, microscopic loss mechanism, and macroscopic microwave absorption performance are also investigated in detail. In addition, under far-field conditions, the shell-like carbon superstructures are characterized by a high degree of conductivity and polarization loss compared with PEC. Besides, the maximum radar cross-section (RCS) reduction of shell-like carbon superstructures reaches 31.19 dB m² compared with PEC under far-field conditions, which again verifies that shell-like carbon superstructures can dissipate more electromagnetic waves in real environments. This work provides a reference for the rational construction of new high-performance carbon superstructure microwave absorbers.