In situ growing fusiform SnO2 nanocrystals film on carbon fiber cloth as an efficient and flexible microwave absorber

Developing highly efficient flexible microwave absorber is of great significance for wearable electronics and aerospace applications. In this work, the fusiform SnO2 nanocrystals film in situ grown on flexible carbon fiber cloth is rationally designed and fabricated through combining air calcination and hydrothermal synthesis. X-ray photoelectron spectrum confirms fusiform SnO2 nanocrystals film and carbon fiber cloth are effectively integrated with strong chemical bonds of COSn. The as-prepared composite exhibits strong reflection loss of −49.1 dB (2.6 GHz) and wide effective absorption bandwidth of 5.8 GHz (11.6–17.4 GHz) with a thin matched thickness of 1.6 mm, surpassing to pure carbon fiber cloth and many SnO2/carbon-based microwave absorbers. The efficient performance originates from well-matched characteristic impedance and multifarious electromagnetic attenuation mechanisms, i.g., dipole orientation polarization, interfacial polarization relaxation, conductive loss, and multiple reflections/scatterings. Especially, differential charge density calculation reveals the uneven charge distribution at SnO2/C interface, which is believed to remarkably enhance interfacial polarization relaxation and contribute to microwave absorption. Our results illustrate that the ingenious integration of nanomaterials on carbon fiber cloth promises a way to achieve efficient and flexible microwave absorbers.