Rational design of microwave absorbing cryogels using microcrystalline cellulose and cellulose-derived nutshell/metal nanoparticles

Abstract

In this research, cryogel scaffolds of cellulose-based cobalt and zinc-cobalt nanostructures were synthesized. For this aim, two types of precursors including pure microcrystalline cellulose (MC) and cellulose obtained from peanut shells (CPS) were pyrolyzed to reduce the cobalt and zinc/cobalt cations and fabricate cryogel scaffolds. The unique morphologies, gained from pyrolyzed celluloses, not only modify the electromagnetic factors but also the reduced metals and synthesized conjugated structures promote the microwave absorbing performance. Five types of cryogels including pyrolyzed microcrystalline cellulose (PMC), pyrolyzed cellulose peanut shells (PCPS), PMC/Co, PCPS/Co, and PCPS/Co-Zn nanostructures were applied as efficient and green microwave absorbers. Finally, the microwave absorption (MA) performance was estimated using VNA. Fascinatingly, polyvinyl chloride (PVC) was applied as a practical MA matrix. According to the results, the architected cryogels demonstrated high-performance MA capabilities. The PCPS/Co-Zn/PVC cryogel derived from the peanut shell cellulose blended by PVC illustrated a maximum reflection loss (RL max ) of −52.13 dB at 23.19 GHz and broad efficient bandwidth of 8.07 GHz with a thin thickness of 1.40 mm, however, the doped PCPS by the Co-Zn demonstrated a RL max of −96.55 dB at 21.24 GHz. Notably, all the samples illustrated mild shielding performances desirable for sustainable development.