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

We report synthesis of the functional ZnO nanostructures (nanowires, nanorods) by a cost effective and efficient method; called composite­hydroxide­mediated (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 220C, of about (500­1500) nm in length, while at 250C; nanorods are formed with length in the range of (200­460) nm and width (10­30) nm. Optical study reveals that ZnO nanorods show only ultra­violet (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 FT­IR. The particle size estimated from the spatial correlation phonon confinement model for the E2 (high) phonon mode. The applied approach is believed to be an efficient, and a direct route for the synthesis of a wide range simple and complex oxide nanostructures for novel electro­optical nanodevices.