Waste cotton-derived magnetic porous carbon for high-efficiency microwave absorption

In this study, using nickel nitrate and waste cotton as precursors, porous carbon combined with well-dispersed Ni nanoparticles were formed via an in-situ growth strategy. Due to the distinction of complex permittivity among different components, the expanded interface in the Ni/C heterostructure could improve the interfacial polarization relaxation, which lead to the enhanced dielectric loss and EM absorbing capability. The results show that excellent microwave absorption properties could be exhibited over a wide frequency range with a filler loading of only 10 wt.%, which compete well with what has been observed in the carbon-based composites with much higher filler loadings. This work provides a low-cost and effective approach for lightweight and high-efficiency microwave absorption, which also greatly facilitates the recycling of waste cotton.