Synthesis and characterization of Fe3O4/polypyrrole/carbon nanotube composites with tunable microwave absorption properties: Role of carbon nanotube and polypyrrole content

•Two types of Fe3O4 nanoparticles were prepared by different processes.•Microwave absorption ability of composites was improved by adding CNT.•Desired reflection loss was achieved by adjusting the Fe3O4 types and Ppy content.•Significant reflection loss (⩽−10dB) was achieved in the bandwidth ranges from 8 to 12.5GHz (X-band).•Excellent permittivity and permeability were achieved by altering the amounts of Ppy and CNT.