▎ 摘　　要

This paper demonstrates both the high-performance microwave absorption properties and the superior thermal stability of graphene/multiwalled carbon nanotubes (MWNTs)/poly(p-phenylenebenzobisoxazole) (PBO) composites synthesized via in situ polymerization of functionalized PBO precursor with graphene oxide/MWNTs nanocomposites, followed by high-temperature calcination. The incorporation of three-dimensional graphene/MWNTs network significantly improved the reflection loss of PBO composites (-50.17 dB at 12.58 GHz) by over 20 times than that of pure PBO (-2.33 dB at 12.58 GHz) with a sample thickness of only 2.6 mm. The effect of graphene/MWNTs content on the microwave absorption performance was also investigated. The graphene/MWNTs/PBO composite shows great promise as a microwave absorber in high-temperature environments.