Constructing Stacked Structure of S-Doped Carbon Layer-Encapsulated MoO₂ NPs with Dominated Dielectric Loss for Microwave Absorption

Abstract

Nowadays the handling of emerging pollution of electromagnetic microwave employing absorption-oriented methods has been paid particular research attention. However, the construction of high-performance absorbers with tailored components and nanostructures using available biomass remains challenging. Lignosulfonate, as a large amount of byproduct of the pulping industry, was selected as the joint source of carbon and doped sulfur, and for the first time, its valorization in microwave absorption was achieved with the help of MoO2 nanoparticles. The constructed stacked structure arising from MoO2 nanoparticles embedded in an S-doped carbonaceous layer provides porous channels and even hollow spheres as well as multiple heterogeneous interfaces, all of which can attenuate microwave efficiently. By adjusting the introduced lignosulfonate dosage, as-fabricated samples present varied microwave absorbency, of which the top performance is delivered by the sample SCM-3 with 3 g of lignosulfonate. When the filler loading is 20%, the optimal reflection loss is up to −53.40 dB with a thickness of 1.7 mm, while the maximum absorbing bandwidth achieves 4.63 GHz from 11.68 to 16.32 GHz at a thickness of 1.9 mm. Also, SCM-2 with 2 g of lignosulfonate also has satisfactory absorbing ability with the help of its unique hollow microspheres. The eye-catching absorbing properties illustrate an excellent synergistic effect between S-doped carbon and MoO2 nanoparticles and further confirm a groundbreaking application of lignosulfonate in microwave absorption.