Figure 2
(A-a–A-c,B-a–B-d,C-b–C-e) HAADF-STEM micrographs of single Co3O4 CPs and C-NT/Co3O4 CPs after sample operation of the interior structure of the microtomed samples using the FIB system. (A-a–A-c) Schematic representation of the sample preparation sequence for the FIB system and (B-a–B-d) the corresponding low-magnification SEM images. The STEM–bright/dark field images of the pristine Co3O4 CPs after subjecting to the FIB system at the middle section (B-a–B-b) and along the top side (B-a,B-d) of the microtomed sample. With the CP resemblance in the NRs (B-c), many protruded particles arched in the pellet bunches and massive constructions of polyhedron mesocrystal facets were shaped like a giant fortress with windows throughout the NR columns. The inset displays a high-magnification image of a single polyhedron of 70 nm. (C-b–C-e) STEM and STEM–EDS mapping of C-NT/Co3O4 CPs microtomed sample after FIB investigation. (C-b) STEM–dark field image of the microtomed sample. (C-c–C-e) STEM–EDS mapping showing the elemental composition of oxygen (c), carbon (d) and cobalt (e) and the corresponding percentage of each element.
