Fig. 3
Reproduced with permission from Ref. [20]. Copyright 2015, American Chemical Society
Schematic representation of the preparation of nanoporous carbon and nanoporous Co3O4 from a ZIF-67 polyhedron with their respective SEM and high-resolution TEM images. The scale bar for SEM image is 500 nm in length. TEM analysis suggests the removal of cobalt nanoparticles from the nanoporous carbon surface after thermal treatment and HF washing (as marked by the white dotted lines). However in the case of Co3O4, the optimized heating conditions result in the conversion of the ZIF-67 polyhedron into an oxide polyhedron.