Studies on evolution of zno Morphology for energy and Environmental applications

Abstract

For its unique physical and chemical properties such as wide bandgap, high electrochemical coupling coefficient, high photostability, high optical absorption, etc., the multifunctional Zinc Oxide is in forefront of modern research. The properties of Zinc oxide are tunable and can be easily manipulated to suit our applications. Though it has been extensively researched, there are still many unknown facets of applications that can be studied for further progress. Hexamethylenetetramine (HMTA) being a heterocyclic organic compound with high solubility in water has been used to work as a building block for self-assembled structure. This particular property is used for growing ZnO nanostructures where they act as a chelating agent forming stable multidentate ligand with the zinc ion thereby encouraging the growth in the single dimension. This property can be used to obtain various morphologies by playing at the reaction parameters which results in the vagary in the reaction rate and alters forces present in the reaction thereby affecting the morphology. It is eminent that super saturation is a criterion for growth in solution and is also closely associated with growth process complicating the development of zinc oxide morphology. The nanorods occur when the system attains saturation such that the intermediate ion complexes formed by the anion and cation surpasses the solubility level of the system. In addition to the nanorods, when the temperature is increased, high precision micro-sized rice shaped structures have also been observed in which the role of hexamine is significant. Further comparison of these rod and rice shaped structures are done with respect to properties and potential applications. At 90°C growth, average crystallite size of the nanorod was calculated to be 51.01nm. At 120°C growth the crystalline size of rice shaped structureswas 31.13nm which is reduced in comparison with growth at 90°C. The disparity in the temperature changes the thermodynamics of the reaction newline newline newline newline