3D Hierarchical Mesoporous Flowerlike Cobalt Oxide Nanomaterials: Controllable Synthesis and Electrochemical Properties

The controllable synthesis of 3D inorganic nanomaterials has attracted much attention. Here, 3D hierarchical mesoporous cobalt oxide (Co 3 O 4 ) nanomaterials with different morphologies are successfully prepared by a facile and surfactant-free solvothermal synthesis of cobalt carbonate hydroxide and subsequent calcination. The morphology of the precursor can be well controlled by adjusting the experimental conditions, such as the proportion of solvent, the amount of urea, and reaction time, thus controlling the structures of the cobalt oxide. Two different plausible growth mechanisms of the red-headed calliandra-like and dandelion-flower-like precursors have been investigated by transmission electron spectroscopy (TEM) of the time-dependent products, respectively. The hierarchical mesoporous materials are tested as the anode materials for lithium ion batteries (LIBs). In particular, the hierarchical mesoporous dandelion-flower-like cobalt oxide shows good rate performance and high specific capacities of 1298 mA h g –1 at the first cycle and 1204 mA h g –1 over 20 cycles, whereas those of the red-headed calliandra-like mesoporous Co 3 O 4 are 1340 and 833 mA h g –1, respectively. In addition, the as-prepared mesoporous cobalt oxides are evaluated as the catalyst for the oxygen reduction reaction (ORR).