Study of the Structural and Optical Properties of the TiO2:Au Nanocomposite Mixture Prepared by Laser Ablation Method

Abstract

In this study, TiO2, Au, and a mixture of TiO2: Au nanoparticles (NPs) were produced using a Nd: YAG pulsed laser. X-Ray diffraction (XRD), Transmission electron microscopy, and Ultraviolet–visible spectroscopy (UV) was used to characterize the produced nanoparticles. The XRD patterns of TiO2 NP showed that the diffraction peaks values were corresponded to the ICDD card number (21-1272) for the anatase form of TiO2 NPs. The XRD patterns of Au NPs values were corresponded to the ICDD card number (00-004-0784) of Au NPs. The XRD patterns the mixture TiO2: Au nanoparticle with mixing ratios (4:1, 3:2 and 2.5:2.5), it was found that the diffraction peaks were (2θ~ 38.138° and 64.687°) of TiO2 nano-particles, and the diffraction peaks were (2θ~ 44.341° and 77.577° ) Au NPs. The average crystalline size of the prepared nanoparticles was determined by Scherer's technique, it was found that the average crystalline size (TiO2 NPs) is (23.36 nm), whereas mixing titanium oxide with gold nanoparticles (TiO2: Au) increased the average crystallite size to (34.18, 34.15, and 34.20 nm) for the mixing ratios (4:1, 3:2, and 2.5:2.5), respectively. The TEM images showed that the TiO2 NPs are light grey in the combination of (TiO2: Au) NPs, while for the ratio (4-1), the Au NPs are dark, spherical spheres. However, when the ratio of Au particles is increased to (2:3), the TiO2 particles remain light grey but are smaller in size. The absorption spectra of pure TiO2 NPs is in the UV spectrum, whereas the absorption spectrum of the (TiO2: Au) mixture shifts towards the wavelengths of visible light in the range (520-540 nm), according to the optical characteristics of TiO2 NPs and a mixture of (TiO2:Au) NPs. The optical energy gap of pure TiO2 NPs is 3.22eV, and it decreases as the proportion of gold nanoparticles in the mixture increases.