Layer-by-layer densely stacked SnO2/rGO composites for ultrathin electromagnetic wave absorption

Tin dioxide (SnO₂), as an easily tunable dielectric material with adjustable polarisation, high dielectric loss and green environment, has become a new choice for building efficient microwave absorbers. However, the single attenuation mechanism of SnO₂ causes its limitation in the effective absorption of electromagnetic waves. In this study, tin dioxide/graphene composites with layer-by-layer dense stacking structure were successfully synthesised. It was further found that the successful loading of SnO₂ particles in graphene flakes formed abundant heterogeneous interfaces and defects, which improved the interface/defect polarisation of the SnO₂/rGO composites. The layer-by-layer dense stacked structure enhances the multiple reflection/scattering of electromagnetic waves inside the material, which strengthens the electromagnetic wave loss. In addition, the close connection between the layers helps the rapid electron transport and ensures the good conduction loss of the composite. The excellent synergy between conduction loss and polarisation loss enables the composites to achieve excellent microwave absorption performance, and the layer-by-layer dense stacking structure ensures the thin thickness of the material, with a minimum reflection loss of −41.79 dB and an effective absorption bandwidth of 4.16 GHz at only 2.0 mm. In addition, fighter radar cross section simulations highlight the potential of SnO₂/rGO composites for radar stealth applications.