Ultralight and Low-Cost Structural Absorbers With Enhanced Microwave Absorption Performance Based on Sustainable Waste Biomass

As a practical microwave absorber, besides satisfying the basic broadband absorption performance, the density, cost, and process complexity are considerable factors in radar stealth and electromagnetic protection fields as well. Here, a simple and economical structural absorber (SA) is proposed to remarkably broaden the absorption bandwidth of biochar from banana peel. By optimizing the size parameters of the unit cell, the optimal SA shows more than 90% absorption in the frequency range from 3.4 to 18 GHz by employing a lightweight porous carbon derived from sustainable biomass. The lightweight porous biochar provides the SA low-density properties with a surface density of only 0.574 g.cm(-2). In such a SA, the greatly enhanced absorption performance mainly originates from the synergistic effect of microscopic and macroscopic scales. By optimizing the pattern design of the SA, the effective impedance is matched with free space in a wide frequency range, thus dissipating more electromagnetic waves through multiple resonances and edge scattering effects. In addition, whether transverse electric or transverse magnetic polarizations, stable broadband absorption can be maintained in a wide incidence angle. Thus, this work provides a new prospect for waste utilization of banana peel and a facile low-cost route to greatly extend the microwave absorption bandwidth.

Automated summary

A simple and economical structural absorber (SA) is proposed in this study, which achieves efficient wideband absorption performance by optimizing design parameters and patterns. The SA, made of biochar derived from banana peel, exhibits low density and stable broadband absorption characteristics in a wide incidence angle range. This research provides a new approach for waste utilization and offers a facile low-cost method to extend the microwave absorption bandwidth.