Rational construction of Ni@CBF-x composites derived from bamboo fungus for enhanced microwave absorption with a 10 % filler content

Abstract

Carbon materials derived from biomass have gained substantial prominence within the domain of microwave absorption (MA). Their eco-friendly attributes, cost-effectiveness, and distinctive morphology have propelled them to the forefront, constituting an effective strategy for the development of sustainable and high-performance microwave absorbing materials (MAMs). Herein, cloud-like porous carbon was derived from bamboo fungus through hydrothermal and carbonization treatment. Subsequently, Ni@carbonized bamboo fungus (Ni@CBF-x) composites were created in situ by introducing magnetic Ni particles. The cloud-like carbon layer derived from bamboo fungus promotes multiple reflections and scattering, enhancing the MA properties of the composites. By adjusting the carbonization temperature, the morphology of Ni particles embedded in the cloud-like porous carbon can be modified, leading to the introduction of numerous heterogeneous interfaces and the construction of 3D conductive networks. Typically, Ni@CBF-800 sample with a filler loading of 10 wt% achieves an impressive minimum reflection loss (RLmin) of –61.2 dB at 10.6 GHz. The effective absorption bandwidth (EAB) of Ni@CBF-1000 sample extends from 6.16 to 11.04 GHz, encompassing 4.88 GHz. Compared to CBF-800 sample, Ni@CBF-1000 sample exhibits a remarkable 171 % increase in EAB, and Ni@CBF-800 exhibits a 50 % increase in RLmin. This exceptional performance can be attributed to four factors, including the strong interfacial polarization induced by the cloud-like porous carbon and Ni particles, the defects created by hydrothermal and carbonization processes, the dipole polarization facilitated by naturally occurring N elements in bamboo fungus, and the magnetic loss caused by magnetic Ni particles. Furthermore, the synergistic coupling of magnetic and dielectric properties serves to optimize the impedance matching characteristics of Ni@CBF-x. These encouraging findings present new avenues for the advancement of magnetic MAMs derived from renewable biomass sources.