Morphology-tuned synthesis of arrayed one-dimensional ZnO nanostructures from Zn(NO3)2 and dimethylamine borane solutions and their photoluminescence and photocatalytic properties

This paper reports morphology-tuned synthesis of arrayed one-dimensional ZnO nanostructures on Ag-coated glass substrates from Zn(NO3)(2) and dimethylamine borane (DMAB) aqueous solutions and their photoluminescence and photocatalytic properties. By adjusting the Zn(NO3)(2) concentration in the solutions, the ZnO nanoneedle arrays, nanorod arrays, and polycrystal films can be obtained. Low Zn(NO3)(2) concentrations result in ZnO nanoneedle arrays. The ZnO nanoneedles grow along the < 0 0 01 > directions. The growth process of the ZnO nanoneedles at low Zn(NO3)(2) concentrations goes through the formation of the equiaxial ZnO granules, the growth of the equiaxial granules into small nanorods, the growth of the small nanorods into nanoneedles, the growth of the nanoneedles in diameter and length, the growth of the nanoneedles into nano-obelisks, and the growth of the nano-obelisks into thick hexangular rods. So the morphologies of the arrayed 1D ZnO nanostructures can be tuned from arrayed nanoneedles through arrayed nanorods and nano-obelisks to arrayed thick hexagonal rods by controlling the Zn(NO3)(2) concentration in the DMAB and Zn(NO3)(2) solutions and/or the deposition time in our process. The ZnO nanoneedle arrays have the largest ratio of the visible to ultraviolet emission and the highest photocatalytic activity. (c) 2011 Elsevier B.V. All rights reserved.