Mechanisms Of Composite-hydroxide-mediated Approach For The Synthesis Of Functional ZnO Nanostructures And Morphological Dependent Optical Emissions

¹National Institute of Lasers and Optronics (NILOP), P.O. Nilore 45650, Islamabad, Pakistan

²Trinity College Dublin, School of Physics, Dublin 2, Ireland

³Department of Mechanical Engineering, Muhammad Ali Jinnah University, Islamabad, Pakistan

Adv. Mater. Lett., 2015, 6 (7), pp 592-599

DOI: 10.5185/amlett.2015.5876

Publication Date (Web): Jul 12, 2015

Copyright © IAAM-VBRI Press

Abstract

We report synthesis of the functional ZnO nanostructures (nanowires, nanorods) by a cost-effective and efficient method; called composite-hydroxide-mediated (CHM) approach. Effect of the processing temperature on the particle size, morphology, and subsequently morphological dependent optical emissions is investigated. Needle-shaped nanowires are obtained at 200 and 220^oC, of about (500-1500) nm in length, while at 250^oC; nanorods are formed with length in the range of (200-460) nm and width (10-30) nm. Optical study reveals that ZnO nanorods show only ultra-violet (UV) emission while bent nanowires demonstrate both UV and green emissions simultaneously. The week green emission at 2.4 eV indicates no efficient trapping of the photo-generated hole in the nanostructures. Phase purity, crystalline structure, size and chemical nature of the product are probed by XRD, EDX, Raman spectroscopy and FT-IR. The particle size estimated from the spatial correlation phonon confinement model for the E₂ (high) phonon mode. The applied approach is believed to be efficient, and a direct route for the synthesis of a wide range of simple and complex oxide nanostructures for novel electro-optical nanodevices.

Keywords

SEM, nanorods and nanowires, Raman spectroscopy, optical properties, morphology dependent emissions.