Lightweight and efficient luffa sponge carbon/Co composites with adjustable electromagnetic wave absorption properties

Biomass material has gained significant popularity due to its potential to meet the requirements of green and sustainable development in modern times. It is widely used in various fields, especially for absorbing electromagnetic waves (EMW). In this study, we used luffa sponge carbon (CLS) as a lightweight and porous carbon source. Through a static reaction and heat treatment process, we successfully loaded coral sheet cobalt onto the surface of CLS to create lightweight and efficient luffa sponge carbon/cobalt (CLS/Co) composites for EMW absorption. We controlled the microstructure and electromagnetic properties of the CLS/Co composites by adjusting the pyrolysis temperature. At 700 °C, the CLS/Co composites showed a minimum reflection loss ( RL min ) of –60.81 dB and an effective absorption bandwidth (EAB) of 5.56 GHz at a very thin thickness of 1.68 mm. Moreover, at a pyrolysis temperature of 800 °C, the absorption strength of the CLS/Co composites reached –50 dB at various thicknesses.