Construction of hollow carbon bowl@polypyrrole composites for excellent microwave absorption

In today's information technology-driven society, microwave absorbing and shielding materials play an increasingly important role in both military equipment and civilian electronic devices. Especially, lightweight and high-efficiency have become crucial metrics for the design of absorbing materials. In this study, we have synthesized a kind of lightweight hollow carbon bowl@polypyrrole (HCBP) composites using a combination of a room-temperature one-step reaction, template etching, high-temperature carbonization, and chemical oxidation. The unique bowl-like architecture, characterized by sharp edges and high curvature, significantly enhances both dipole and interfacial polarization losses. The coating of thin polypyrrole films on the surfaces of carbon bowls further reinforces these polarization losses while effectively modulating the surface electromagnetic characteristics of the composite. As a result, the HCBP composite demonstrates exceptional electromagnetic wave absorption performance, achieving a minimum reflection loss of −62.15 dB at 16.66 GHz with a thickness of 2.16 mm, along with an effective absorption bandwidth of 6.88 GHz at 2.49 mm thickness. This advancement opens new possibilities for the precise design of dielectric composite electromagnetic wave absorbers with both strong absorption and broad bandwidth characteristics.