Caracterización vibracional del nanocompuesto de TiO2/Ag a partir de su síntesis por impregnación húmeda

Abstract

Metal oxide-based substrates, such as TiO2, have attracted the attention of the scientific community due to their high amplification capacity and chemical stability. In addition, the addition of silver nanoparticles to the substrate, forming the TiO2@Ag nanocomposite, is of interest to the industry because it can increase the catalytic capabilities of the material and generate a SERS plasmonic resonance effect. Therefore, this research work focuses primarily on studying the vibrational properties of the TiO2 composite with silver nanoparticles, as well as its precursor, the commercial material Degussa P-25, and characterizing its Raman spectroscopy starting from the chemical synthesis of the substrate. To achieve this objective, the chemical synthesis technique called wet impregnation was used, which allows the preparation of homogeneous substrates with high purity and particle size control. Structural and optical studies of the substrate were then carried out using spectroscopic techniques such as Raman spectroscopy, X-ray diffraction spectroscopy (XRD) and dynamic light scattering (DLS). This allowed the characteristic peaks of the anatase phase of TiO2 to be observed, together with the appearance of an unusual peak at 50 cm−1, not previously reported in the literature. This peak was observed both in the Degussa P25 base material and in the nanocomposite samples, although its intensity is greater in the latter. Additionally, the analyses carried out suggest the possible interference of peaks from the silver formed in clusters, which suggests an effect of increasing the intensity of the unusual peak in the nanocomposite spectra. One of the samples was evaluated by X-ray diffraction (XRD) to confirm the presence of the anatase, rutile and silver nanoparticle phases. XRD results show that it contains a combination of these three species, in agreement with comparisons with theoretical diffractograms. Also, variations in molar concentration and temperature control during the synthesis process were shown to have an influence on the particle size.