Polyethylenimine-Guided Self-Twin Zinc Oxide Nanoarray Assemblies

Well-oriented and twin ZnO nanoarray assemblies have been fabricated using the aqueous solution deposition technique at low temperature. Polyethylenimine was added to the zinc nitrate hexahydrate-hexamethylenetetramine aqueous Solution during the deposition processes at 88 degrees C. The formation mechanism of twin ZnO nanoarray assemblies was clarified by X-ray diffraction, a field emission scanning electron microscope and high-resolution transmission electron microscope. The addition of polyethylenimine resulted in the formation of zinc hydroxide and zinc hydroxide nitrate dihydrate (Zn(5)(OH)(8)(NO(3))(2)center dot 2H(2)O) as the intermediate phases. In Situ forced hydrolysis of the cloudlike intermediate phase Zn(5)(OH)(8)(NO(3))(2)center dot 2H(2)O effectively provided nucleation sites and reduced the interface energy barrier for ZnO crystal growth, and promoted preferential growth along the [0001] direction by heterogeneous nucleation through the dissolution-reprecipitation of zinc hydroxide. The formation of twin ZnO assemblies Should be attributed to kinetic confinement and thermodynamic motivation.