A solvent-free process enabling ZnO/porous carbon with enhanced microwave absorption

Exploring a simple, rapid, solvent-free synthetic method for mass production of cheap, broadband microwave absorbers remains the main challenge. Here, a mild solvent-free procedure is reported to synthesize zinc oxide nanoparticles (ZnO NPs) embedded in porous carbon derived from mixing sucrose and zinc nitrate hexahydrate. The characteristic morphology and the ZnO NPs distribution in these composites were tuned using the different raw materials proportions. The mesoporous structure of porous carbon benefits the compositional advantages between carbon foam and ZnO NPs. The optimal synthesized ZnO/C-2 carbon material demonstrates the strongest absorption of –41.7 dB with a frequency of 14.5 GHz at a thin thickness of 2 mm, and its widest effective absorption is close to 6 GHz (12.2–17.8 GHz). This work produces a feasible route for the sensible design of other effective microwave absorbers for large-scale production.