Preparation and study of Al2O3@PPy@rGO composites with microwave absorption properties

In this work, Al 2 O 3 @PPy@rGO composites were successfully synthesized by a “coating-coating” route. The structure of Al 2 O 3 @PPy@rGO composites was characterized by XRD , Raman and SEM. The coaxial wire method was used to measure the electromagnetic properties of Al 2 O 3 @PPy@rGO composites, which was carried on the vector network analyzer (VNA, 3672A/B/C-S) over the 2–18 GHz frequency range. Compared with Al 2 O 3 (about 50 nm), the particle size of Al 2 O 3 @PPy composites (about 70 nm) enhanced, which verified the alumina was coated by PPy . In addition, the Al 2 O 3 @PPy composites are tightly attached by the rGO with a diameter of about 30 nm Al 2 O 3 @PPy@rGO composites have excellent thermal stability, and they remain 53 wt% when the temperature is up to 800 °C. When the thickness of Al 2 O 3 @PPy@rGO composites is 3.0 mm, they reach the maximum reflection loss of −39.7 dB at 13.2 GHz with 15 wt% Al 2 O 3 @PPy@rGO-wax. And the broad effective microwave absorption bandwidth of Al 2 O 3 @PPy@rGO composites is 5.5 GHz in 10.5–16.0 GHz. In addition, the electromagnetic wave absorption mechanism of Al 2 O 3 @PPy@rGO composites was analyzed.