Synthesis and characterization of silver silica nanocomposite materials via sol-gel technique / Taifunisyam Taib

Taifunisyam , Taib (2023) Synthesis and characterization of silver silica nanocomposite materials via sol-gel technique / Taifunisyam Taib. PhD thesis, Universiti Malaya.

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Abstract

Various filling fractions of silver silica nanocomposites (Ag-SiO2 NC) were successfully synthesized via sol-gel technique and deposited onto indium tin oxide via electrophoretic deposition (EPD). The size of Silver Nanoparticles (AgNPs) synthesized by reduction method was determined to be within 20-30 nm, homogeneous and spherical in shape observed from Transmission electron microscopy (TEM) images. TEM images also confirmed that the particle distance between AgNPs in the Ag-SiO NC varies according to the filling fractions. The increase in crystalline phase was observed by the increase of peaks intensity of X-ray diffraction (XRD) spectra as the increase of AgNPs amount in the nanocomposites. UV–vis spectroscopy shows that the intensity of the Ag–SiO2 NCs peak is greatly reduced with a clear and sharp absorption peak. The Fourier-transform Infrared (FTIR) spectra shows similar peaks for all the various filling fractions of Ag-SiO2 NC. However the peaks shown slightly shifted indicating the existence of the AgNP within the silica nanostructures. Spectroscopy Ellipsometry shows that the effective permittivity and refractive index obtained from the optimum filling fraction are -0.88 and 0.90, respectively. The use of 4-Aminobenzenethiol (4-ABT) as the probe molecule on the substrate greatly enhances the Surface-enhanced Raman Spectroscopy (SERS) signal of the nanocomposites. The results from different pH values confirm that the substrate is stable and gives the strongest SERS enhancements in alkaline environment. The photoelectrochemical behavior of Ag-SiO2 NC thin films was also investigated. Thin films grown at higher Ag composition showed good photoelectrochemical behavior.

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