Flexible SiO2/rGO aerogel for wide-angle broadband microwave absorption

Graphene aerogel has been a promising microwave absorber due to ultralow density and strong dielectric loss ability. However, its intrinsic brittleness, and poor absorbing properties because of impedance mismatch severely hinders practical engineering applications. Herein, flexible silica fibers with excellent impedance matching properties were introduced into graphene honeycomb structures to co-construct a dual-structure aerogel (GS) by eco-friendly and low-cost technology. The unique dual-structure significantly enhances its resilience, enabling it to rebound after 1000 cycles of 75% compression. In addition, it can withstand 450 times of 180° folding and 360° rotation without damage, featuring remarkable flexibility and reliability. Furthermore, the simulation and experimental results indicate that GS has excellent wave absorbing performance. When the thickness is 6 mm, the effective absorption bandwidth is 32.55 GHz; when the thickness increases to 10 mm, the reflection loss is less than −8 dB in the range of 2.79–40 GHz. Moreover, the reflection loss remains almost constant when the oblique incidence angle ranges from 5° to 45°, which further demonstrates the critical role of impedance matching in enhancing the microwave absorption performance. These superior characteristics make GS an ideal candidate for many microwave absorption applications such as flexible electronics and aerospace.