The detection of organic and inorganic compounds using electrochemical sensors has garnered attention due to their low-cost fabrication and excellent sensitivity. To enhance the sensitivity of the sensor using metal oxides as active materials, defect states such as oxygen vacancies have been studied. These defects operate as donor levels near the conduction band of the metal oxide. In this study, we present the synthesis of TiO2 nanotubes decorated with Ag spheres, along with an investigation into their chemical, structural, and optical properties for electrochemical sensing applications. TiO2 nanotubes were synthesized through a three-step anodization process, while Ag spheres were deposited using electrochemical deposition. The electrolyte solution for the growth of TiO2 nanotubes consisted of ammonium fluoride and ethylene glycol, while silver nitrate and citric acid were employed as the electrolyte solution for Ag sphere deposition. FE-SEM analysis revealed the successful deposition of Ag spheres with a spherical morphology over TiO2 nanotubes, with the morphology being significantly influenced by the concentration of organic acid in the electrolyte solution. Stoichiometry analysis was performed on both the TiO2 nanotube film and on the film decorated with Ag spheres. Additionally, the band gap energy was calculated from the diffuse reflectance spectroscopy (DRS) spectrum. According to photoluminescence analysis, a larger area associated with oxygen vacancies in TiO2 nanotubes decorated with Ag spheres was identified. The presence of localized energy levels within the band gap resulting from oxygen vacancies and Ag spheres led to a reduction in the band gap energy of the semiconductor. This phenomenon is particularly relevant for creating more active sites suitable for the adsorption of compounds in electrochemical sensing applications.^1,2

References

[1] A. Arenas-Hernandez, C. Zuñiga Islas, M. Moreno. Appl. Sci., (2022) 12, 3690.

[2] Singh, K.; Maurya, K. K.; Malviya M. J. Anal. Test., (2023) 8, 143.