Biomass-Derived Integrated Hierarchical Porous Carbon Embedded with Ni@C Nanoparticles for High-Performance and Cost-Effective Microwave Absorbent Design

Abstract

High-performance and cost-effective microwave absorbing materials are of vital importance in not only military but also civil fields. Here, an in situ generation-carbonization one-step method is proposed to synthesize excellent absorbents based on a common solid waste, willow catkins. The results demonstrate that the microwave absorption performance has been successfully improved owing to the magnetic particles, the core–shell nanoparticles, and the hierarchical porous structure, which results in strong conductivity loss, dielectric loss, magnetic loss, interface polarization, and multiple scattering. The maximum reflection loss (RLmax) reaches up to −50.66 dB and −49.09 dB, respectively, at 16.6 and 17.1 GHz with the thickness of 1.65 mm, resulting in double-peak absorption. What’s more, the effective absorption bandwidth (EAB, RL < −10 dB) can get up to 5.7 GHz (from 12.4 to 18 GHz) with the thickness of 1.84 mm. Great absorption performance can be obtained simply through impregnation and carbonization, which constructs a fruitful and cost-effective paradigm for resource utilization of solid waste such as willow catkins.