University of Massachusetts Lowell, United States
pp. 318 - 320
Keywords: gold nanoparticles, metal oxide, photoluminescence, thiol, zinc oxide
Metal oxide nanoparticles are surprisingly reactive, and some undergo changes in color or in their photoluminescence (PL) spectra upon reaction. In the latter case, visible emission arises from electron decay from surface related states, and PL changes are an indicator of chemisorption. Surface science techniques have been used to investigate adsorption of various molecules, including thiols, from the gas and solution phases, on metal oxide powders and films and to measure changes in the electronic structure of the surface due to adsorption. Examples of metal oxide nanopowders that have been studied include zinc oxide, zirconium oxide, gold oxide and tungsten oxide. In many cases it is shown that thiols reduce metal oxides to metals, with concomitant oxidation of the thiol to disulfide. Dithiols can also be used as chemical linkers to attach gold nanoparticles to metal oxides. Methods of sintering the nanocomposites to remove the ligands have been explored, and the optical and photocatalytic properties of the resulting materials have been measured. Applications of this research include chemical sensing, turning of optoelectronic devices, and photocatalysis to decompose hazardous materials.