Dependence of Spectroscopic Properties of Copper Oxide Based Silica Supported Nanostructure on Temperature

Abstract

Various concentrations of copper were embedded into silica matrix to xerogel forms using copper source Cu(NO3)2∙3H2O. The xerogel samples were prepared by hydrolysis and condensation of Tetraethyl Ortho-Silicate (TEOS) with determination of new molar ratio of the components by the sol-gel method. After ambient drying, the xerogel samples were heated from 60 to 1000˚C at a slow heating rate (50°C/h). The absorption and transmittance spectra of the gel matrices were heat treated at different temperatures. The loss of water and hydroxyl group from the silica network changed the spectral characteristics of Cu2+ ions in the host silica. The shift observed for the broad band of the absorption spectrum of the samples heated up to 600°C was attributed to the legend field splitting and partial removal of the hydroxyl group from the silica matrix. Absorption spectrum of the samples heated to 1000°C confirmed the conversion of Cu2+ ions to Cu+ ions. The effects of thermal treatment were characterized by Fourier Transmission Infrared (FTIR) and Raman spectroscopy at different temperatures. Also, the Transmission Electron Microscope (TEM) micrographs confirmed the average pores size of about 50 nm.