Hydrothermal Synthesis of Hierarchical Nanocolumns of Cobalt Hydroxide and Cobalt Oxide

In this paper, we report a facile method to prepare high-yield one dimensional hierarchical beta-Co(OH)(2) nanocolumns through one-step hydrothermal synthesis with hydrazine hydrate and Na3PO4 as morphology-directing agents, which play important roles in the formation of hierarchical nanocolumn morphology. The hierarchical Co3O4 nanocolumns are obtained by the beta-Co(OH)(2) nanocolumns annealed at 400 degrees C for 4 h. The formation mechanism of hierarchical nanocolumns has been clearly demonstrated by studying morphology evolution processes of beta-Co(OH)(2) nanocrystals upon reaction time, which undergo two steps, the formation of nanorods and then growing sideways in the form of thin nanoplatelets to form hierarchical nanocolumns. Moreover the UV-vis spectra and magnetic properties Of Co3O4 nanocolumns also have been investigated.