Transition metal-doped ZnO nanorods synthesized by chemical methods

We report synthesis of ZnO nanorods doped with Mn, Cr, and Co by a hydrothermal method from aqueous solutions of zinc nitrate hydrate, TM (TM=Mn, Cr, Co) nitrate hydrate, and hexamethylenetetramine. The morphology of the doped ZnO structures was studied by scanning electron microscopy. The composition was determined from energy dispersive X-ray spectroscopy. The relationship between the solution concentration and the incorporation of the transition metal was studied. The addition of TM nitrate hydrate results in the change of the shape of ZnO nanorods, as well as in the change of their preferential orientation with respect to the substrate. Possible reasons for these changes are discussed. Finally, the differences in the properties of doped nanostructures were investigated by photoluminescence. While the addition of TM nitrate hydrate to the starting solution obviously affects the morphology and optical properties, further optimization of the hydrothermal growth conditions is needed in order to improve incorporation of TM metal ions and resulting morphology of the nanostructures.