Synthesis and microwave absorption performance of layered hard carbon embedded with ZnO nanoparticles

•Layered hard C embedded with ZnO nanoparticles were synthesized by pyrolysis route.•The novel hard C/ZnO composites exhibit excellent microwave absorption properties.•Defects and organic functional groups in hard C lead to strong polarization loss.•Hard C/ZnO interfacial polarization significantly enhance the dielectric loss.