Electromagnetic (EM) absorption is paving the way to overcome the challenges related to conventional shielding strategy against EM pollution through sustainable energy dissipation. As characteristic functional media that can interact with electric or magnetic field branch, EM wave absorption materials (EWAMs) have received extensive attention and realized considerable development in the past two decades, where carbon-based composites are always considered as promising candidates for high-performance EMAWs due to their synergetic loss mechanism as well as diversified composition and microstructure design. Recent progress indicates that there is more and more interest in the fabrication of carbon-based composites with unique core–shell configuration. On one hand, core–shell configuration usually ensures good chemical homogeneity of final products and provides some positive protections for the components with susceptibility to corrosion, on the other hand, it creates enough heterogeneous interfaces between different EM components, which may bring enhanced polarization effect and intensify the consumption of EM energy. In this review, we firstly introduce EM wave absorption theory, and then highlight the advances of core–shell engineering in carbon-based composites in terms of built-in carbon cores and built-out carbon shells. Moreover, we also show some special core–shell carbon-based composites, including carbon/carbon composites, assembled composites, and decorated composites. After analyzing EM absorption performance of some representative composites, we further propose some challenges and perspectives on the development of core–shell carbon-based composites.

Heteroatom-doped carbon nanomaterials have attracted significant attention as anode materials for sodium-ion batteries (SIBs). Herein, we demonstrate a conjugated polymer-mediated synthesis of sulfur and nitrogen co-doped carbon nanotubes (S/N-CT) via the carbonization of sulfur-containing polyaniline (PANI) nanotubes. It is found that the carbonization technique greatly influences the structural features and thus the Na-storage behavior of the S/N-CT materials. The carbon nanotubes developed using a two-step carbonization process (heating at 400 ℃ and then at 900 ℃) exhibit a high specific surface area, enlarged interlayer distance, small charge transfer resistance, enhanced reaction kinetics, as well as a large number of defects and active sites; further, they exhibit a high reversible capacity of 340 mAh·g^–1 at 0.1 A·g^–1 and a remarkable cycling stability with a capacity of 141 mAh·g^–1 at 5 A·g^–1 (94% retention after 3, 000 cycles). Direct carbonization of conjugated polymers with a specific morphology is an eco-friendly and low-cost technique for the synthesis of dual atom-doped carbon nanomaterials for application in energy devices. However, the carbonization process should be carefully controlled in order to better tune the structure–property relationship.