Functionalization and synthesis of biomass and its composites as renewable, lightweight and eco-efficient microwave-absorbing materials: A review

Electromagnetic pollution is posing a threat to human health and the operation of electronic/electrical devices. It refers to the unwanted electromagnetic waves/signals radiated from electronic devices/equipment. Microwave absorbers/absorbing materials have been developed to mitigate the problems associated with this kind of pollution. Recently biomass-based materials have attracted researchers for absorber applications attributing to their salient features like low cost, lightweight, renewable, eco-friendly, and ease of availability. The application of biomass as a microwave absorber not only solves the radiation problem but also renders an eco-friendly environment. The biomass is carbonized to produce porous carbon to be used as a microwave absorber. The microwave absorption of biomass-based materials depends on their composition, microstructure, and pore size. Besides carbonization, the activation method also has a great influence on the characteristics of biomass. This article presents a comprehensive review of the research progress in renewable biomass-tuned microwave absorbers accompanied by different types of biomass-based materials, synthesis techniques, and composites using metals, oxides, sulfides, carbon nanotubes, polymers, etc. The performance metrics and mechanisms associated with microwave absorption have also been put thereof.