Figure 4

(a) is the low-magnification TEM image to show the achieved Co3O4 nanoparticles@graphitized carbon peapods array after being removed from Ti foil. (b) is the locally magnified TEM image to further confirm the peapoded structure and (c) is the HRTEM image to characterize the crystal structures of the encapsulated Co3O4 nanoparticles and the graphitized carbon fibers from the selected area in (b).