Yolk-shelled Co@SiO2@Mesoporous carbon microspheres: Construction of multiple heterogeneous interfaces for wide-bandwidth microwave absorption

•Yolk-shelled Co@SiO2@Mesoporous carbon microspheres are controllably prepared.•Mesoporous carbon shell and hollow cavity are obtained by etching SiO2 in one step.•Effective absorption bandwidth is 9.6 GHz (8.4–18 GHz), covering whole X, Ku bands.•The attenuation mechanism of enhanced microwave absorption performance is revealed.