Facile controlled synthesis of highly ordered dendritic and flower-like cobalt superstructures

Dendritic and flower-like cobalt superstructures have been selectively prepared by a facile hydrothermal route. The synthetic process involves the chemical reduction of cobalt ions and the oriented growth of cobalt nanocrystals under kinetic control independent of surfactants or external magnetic field. The dendritic superstructures are found to be composed of well-aligned metallic cobalt dendrites radiating from the center. Upon adding 0.3 M of potassium sodium tartrate (C4H4KNaO6·4H2O) into the reaction system, flower-like cobalt superstructures consisting of spear-like petals attached to a mutual core can be prepared instead of the dendritic ones. The size and morphology of the products can be tailored by properly tuning the process conditions and the component of the reaction solution. The magnetic properties of the products have been studied as well and the results demonstrate that the products present ferromagnetic properties related to the corresponding microstructures. Based on a series of contrast experiments, the probable growth mechanism and fabrication process of the products have been proposed. This work provides a facile and effective strategy to fabricate self assembled cobalt hierarchical superstructures with tunable morphologies.