Alignment, Morphology and Defect Control of Vertically Aligned ZnO Nanorod Array: Competition between Surfactant and Stabilizer Roles of the Amine Species and Its Photocatalytic Properties

We demonstrate effective control of the morphology, defect content and vertical alignment of ZnO nanorod (NR) arrays grown by a solution method by simply varying the hexarnine concentration during growth. We show that the amine acts both as a growth 'stabilizer' and 'surfactant' and controls both Zn release for ZnO formation and caps non-polar planes, respectively. Competition between these 'stabilizer' and 'surfactant' roles facilitates morphology, alignment and defect content control of 1D ZnO NR arrays. Well aligned, prismatic, defect (Zn interstitial) controlled ZnO NR arrays grown with a 1M amine concentration show higher photocatalytic degradation of Methylene Blue dye solutions under UV irradiation. Shallow donor zinc interstitials readily supply electrons which may increase the space charge near the nano-catalyst surface. The increased band bending associated with the interfacial electric field in the space charge region photogenerated carriers and thus enhance the photocatalytic performance. Understanding 1D ZnO NR arrays holds great promise for tailoring ZnO NR functionalities for various may then better facilitate the separation of the role of amine in the solution growth of potential applications.