Synthesis and characterization of Co/cenosphere core-shell structure composites

► Co coated cenosphere composites are successfully fabricated by heterogeneous precipitation thermal reduction method using metal salts, ammonium hydro-carbonate and cenospheres as starting reagents for the first time. ► Relatively uniform, smooth and compact Co coating has been successfully coated onto cenospheres, and the grain size is about 24.5 nm. ► The magnetic properties of Co coated cenosphere composites are affected by core layer.