Preparation and Functionalization of ZnO Nanowires for the Application in Infrared and Raman Sensing System

Autor: Satheeshkumar Elumalai, 沙帝施
Rok vydání: 2014
Druh dokumentu: 學位論文 ; thesis
Popis: 102
Nanomaterials have attracted significant attention in recent years for various fascinating applications, including ultrasensitive chemical/biological sensors, recording media, electronic circuits, nano-medical treatments, and so forth. A major goal in current research and development efforts in nanoscience and nanotechnology is to fabricate functional materials by integrating bottom-up chemical assembly schemes for use optical spectroscopic application. Vibrational spectroscopy is indispensible in analytical science because the analysis of vibrational spectra can tell us a great deal about the chemical identity and even the environment of the molecules being detected, Indeed, linear vibrational spectroscopy, for example, infrared absorption (IR) or Raman scattering are widely utilized in various research fields because their convenience. Zinc oxide nanostructures exhibit unique chemical properties and can be prepared easily in the forms of nanoparticles, nanowires, nanobelts, nanospring and others. Among ZnO nanostructures, nanowires have attracted more attention for chemical sensing purposes due to their high surface area and well-defined crystallinity. The high surface area improves sensitivity and speed in detection and the crystalline properties improve selectivity in detection. In Chapter 1, the basic concepts and the current progresses of the synthesis of nanomaterials for the application in infrared (IR) and Raman spectroscopy are reviewed and described. In Chapter 2, the surface of ZnO nanowire was characterized by the adsorption behavior of gasses molecule (volatile organic compounds, VOCs) via Fourier transform Infrared (FTIR) spectroscopy. Due to the ZnO nanowire chemistry, the gases molecule has a different adsorption behavior on the surface of ZnO nanowire. Hence the surface properties of the ZnO nanowires were characterized during the detection of VOCs. The results reveals that, Zn-rich polar surface of nanowires are preferential adsorption towards to alcohol and ketone; whereas case of Zn-O rich ion-pair (non-polar side-wall plane) were mostly preferred to interact with the compound having amine functional group and chlorinated aromatic compounds which is partially interact to both surface of ZnO nanowire. In Chapter 3, method to assemble metal nanoparticles into a three dimensional (3D) nanostructure was proposed for preparation of substrates for Surface enhanced-Raman scattering (SERS) measurements. Silver nanoparticles (AgNPs) decorated ZnO nanowires (ZnO NWs) with photoreduction method was demonstrated. As prepared multilayer 3D SERS substrate with enhancement factor in the order of 2.77 ✕ 107. In Chapter 4, a new method to prepare silver nanoparticles decorated ZnO NWs on filter paper substrate was proposed. This method involved the use of photoreduction in decoration of silver nanoparticles on pre-grown ZnO NWs on filter paper substrate. To understand the influence of uniform growing of ZnO nanowires on paper substrate, factors, such as effect of concentration of ZnO seeds, growing time of ZnO NWs, and concentration of growth solution, were systematically studied. The prepared substrates were examined their performances in SERS measurements to examine their impacts to fabricate high performance SERS substrates. In Chapter 5, an analyte-induced photoreduction preparation of silver nanoparticles (AgNPs) for colorimetric detection of tyrosine was proposed in this chapter. Tyrosine molecule can reduce the silver ion under UV photochemical irradiation and changes of as formed silver nanoparticle can be seen by naked eye. Based on the optimal condition, the detection limit was estimated around 100 nM by colorimetric method and 500 nM by visual detection. In Chapter 6, the summaries of the work presented in this thesis are given.
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