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

Taj Muhammad Khan1, 2*, M. Zakria1, Rana I. Shakoor1, 3, M. Raffi1, Mushtaq Ahmad1

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

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 220oC, of about (500-1500) nm in length, while at 250oC; 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.

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