Magnetic core-shell structure in-situ encapsulated in bamboo-derived carbon skeleton for efficient microwave absorption

Highlights: • Bamboo-derived magnetic composites was prepared via an in-situ growth process. • The hybrids exhibit magnetic core-shell structure encapsulated in carbon skeleton. • Strong RL surpassing − 40 dB is realized at both high and low frequencies. • The microstructure, graphitization, magnetic and absorption properties can be tuned. -- Abstract: A fast renewable bamboo source is first adopted to synthesize carbon-based magnetic composites as efficient and sustainable microwave absorbers through a carbothermal in-situ growth process. The magnetic core-shell particles uniformly encapsulated in porous carbon skeleton can promote magnetic loss and graphitization of carbon shell. The gradient graphitization of graphitic shells and disordered framework is favorable for conductive loss and polarization relaxation. By controlling the magnetic content, the microstructure, magnetic property, graphitization and absorbing performance of the composites can be delicately manipulated. As expected, the strong reflection loss surpassing − 40 dB is achieved at both high frequency of 14.1 GHz (1.9 mm) and low frequency of 5.5 GHz. Meanwhile, a wide effective bandwidth of 4.7 GHz covering from 6.6 GHz to 11.3 GHz is achieved. This work demonstrates that the combination of bamboo carbon with magnetic cores could provide a perspective for refining low frequency and thin thickness characteristics for plant-derived microwave absorption.