Synthesis and characterization of shape-controlled mesoporous Co3O4 hierarchical nanostructures

Hierarchical Co3O4 mesoporous nanostructures have been synthesized by a hydrothermal method combined with subsequent calcination. These hierarchical nanostructures were characterized by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. According to varying the reaction time, three typical kinds of Co3O4 hierarchical nanostructures, i.e., free-standing nanowalls, nanowires-nanowalls, and, nanosheets-nanowires-nanowalls were obtained. The formation of mesoporous Co3O4 nanostructures may be due to the thermal decomposition of the corresponding precursor. Magnetic measurement indicates that the vacuum-annealed Co3O4 samples show room temperature ferromagnetism, while the as-prepared samples are paramagnetic.