In Situ Generated H₂ Bubble-Engaged Assembly: A One-Step Approach for Shape-Controlled Growth of Fe Nanostructures

The current work describes a simple and convenient approach that allowed for the facile synthesis of Fe nanostructures with morphologies varied from novel solid nanofibers, to nanotubes, and even to hollow nanospheres without using any surfactants and/or solid templates. The morphologically controlled growth of Fe nanostructures can be realized by reducing iron(II) sulfate heptahydrate with sodium borohydride in a carefully devised kinetically tuned procedure, in which the H 2 bubbles generated in situ in the reaction system directed the growth of Fe nuclei. Kinetic factors such as the concentration of the reducing reagent and the reaction temperature can be easily utilized to tune the formation and growth of Fe nuclei and, therefore, the final morphology of the resultant Fe nanostructures. The iron nanostructures were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating-sample magnetometer (VSM). The one-step H 2 bubble-engaged assembly approach reported here can be readily explored for fabricating other magnetic metal nanostructures, and the resulting Fe nanostructures are expected to find use in a number of applications involving MR imaging, magnetic drug delivery, nanoscale encapsulation, and so forth.