Carbon/Carbon-Ag-Fe3O4 dual shell hollow microspheres: High efficient pyrolysis synthesis and broad band microwave absorption

Hollow microspheres with hybrid shell hold great potential to be employed as microwave absorbents aiming at high efficient dissipation and lightweight design, but their rational design and high efficient construction remain a big challenge. In the present work, novel Carbon/Carbon-Ag-Fe3O4 dual shell hollow microspheres (DSHM) were designed and prepared through a facile two step calcination induced pyrolysis route with distinct temperature. It is found that DSHM with various shell composition and microstructure can be obtained simply via tuning the calcination condition and the composition of the starting materials, which further determines the electromagnetic and microwave absorbing properties. The microwave absorption measurements demonstrate that with properly controlled shell composition, the optimized product presents an effective absorption bandwidth (EAB) of 7.8 GHz at a relatively low thickness of 2.0 mm. The DSHM reported here possess great potential to be employed as high efficient microwave absorbent towards multicomponent and wideband absorbing design. (C) 2022 Elsevier B.V. All rights reserved.