Large-Scale Fabrication of Sub-20-nm-Diameter ZnO Nanorod Arrays at Room Temperature and Their Photocatalytic Activity

Abstract

We report a very simple and mild wet-chemical synthesis of ZnO nanorods to fabricate sub-20-nm-diameter ZnO nanorod arrays. These large-scale arrays could be obtained by immersing a Zn sheet in an ammonia aqueous solution containing Al3+ ion at room temperature (25 degrees C) and normal atmospheric pressure (1 atm). This method uses little energy and requires no complex experimental procedures or equipment. The Zn ions were provided by the Zn sheet; as a consequence, the growth process is self-limiting. The ZnO nanorods produced were similar to 250 nm long and similar to 18 nm in diameter. On the basis of the results, we propose a mechanism for the growth of the ZnO structures on the Zn sheet with Al3+ ion-containing ammonia aqueous solution. The high surface-to-volume ratio of the sub-20-nm-diameter ZnO nanorod arrays results in enhanced photocatalytic activity.