Well-controlled Core-shell structures based on Fe3O4 nanospheres coated by polyaniline for highly efficient microwave absorption

• Conductive polymer materials (PANI) uniformly coat Fe 3 O 4 nanospheres to form a core–shell structure. • RL of Fe 3 O 4 @PANI core–shell nanospheres can reached −55.5 dB at 17.3 GHz with a low thickness of 1.6 mm. • Effective absorption bandwidth was up to 6.6 GHz with thickness of 1.5–2.0 mm. In this paper, Fe 3 O 4 @polyaniline (Fe 3 O 4 @PANI) core–shell nanospheres have been successfully synthesized via a facile single mode microwave-assisted hydrothermal method following an in-situ free radical chemical oxidative polymerization, which are used as microwave absorption materials. Conductive polymer material PANI is uniformly coated on the surface of Fe 3 O 4 nanospheres of 100 nm to form a core–shell structure. Microwave absorption ability of Fe 3 O 4 nanospheres coated by the conductive PANI is significantly enhanced. The strongest reflection loss of Fe 3 O 4 @PANI core–shell nanospheres can reach −55.5 dB at the microwave frequency of 17.3 GHz under a low thickness of 1.6 mm. Moreover, the effective absorption bandwidth is up to 6.6 GHz under thickness of 1.5–2.0 mm. Fe 3 O 4 @PANI core–shell nanospheres with excellent microwave absorption properties are potential candidates at broad application of the high-frequency electromagnetic waves range.