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

• Published in: Crystal growth & design Vol. 14; no. 6; pp. 2873 - 2879
• Main Authors: Ranjith, Kugalur Shanmugam, Pandian, Ramanathaswamy, McGlynn, Enda, Rajendra Kumar, Ramasamy Thangavelu
• Format: Journal Article
• Language: English
• Published: Washington,DC American Chemical Society 04.06.2014
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Growth from solutions; Materials science; Methods of crystal growth; physics of crystal growth; Methods of nanofabrication; Nanoscale materials and structures: fabrication and characterization; Other topics in nanoscale materials and structures; Physics; Quantum wires; Radiation effects; Amines; Catalysts; Photocatalysis; Space charge; Surfactants; Zinc; Methylene blue; Electric field effects; Morphology; Growth mechanism; Bending; Charge carrier generation; Crystal growth from solutions; Arrays; Nanorod; Nanostructured materials; Nanomaterial synthesis
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/cg5001792

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 hexamine 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 may then better facilitate the separation of photogenerated carriers and thus enhance the photocatalytic performance. Understanding the role of amine in the solution growth of 1D ZnO NR arrays holds great promise for tailoring ZnO NR functionalities for various potential applications.