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.
