Properties of sol-gel synthesized multiphase TiO2 (AB)-ZnO (ZW) semiconductor nanostructure: An effective catalyst for methylene blue dye degradation

The present study, describes the structural, electrical, and the photocatalytic activity of sol-gel synthesized TiO2- ZnO nanostructure. The synthesized mixed oxide nanostructure is characterized by XRD, FTIR, Raman, UV-Vis, FESEM, DLS and Impedance Spectroscopy analyses. In addition, photocatalytic activity of multiphase TiO2 (TAB)-ZnO (ZW) nanostructure is analysed using Methylene Blue dye as the model dye under UV and Visible light illumination. The XRD analysis confirms the bi-phase TiO2 and mono-phase ZnO in the multiphase TiO2-ZnO nanostructures. The average crystallite size of 33 nm has been estimated using Scherrer formula. The crystallite size and mechanical properties such as strain, stress, and other parameters are analysed using Williamson-Hall model. The FTIR spectrum shows the characteristics absorption peaks of TiO2 and ZnO at 679.44 and 432.79 cm-1 respectively, and reveals the presence of TiO2 and ZnO in the synthesized multiphase nanostructure. The optical band gap is calculated using Tauc relation with the data obtained from UV-Vis spectrometer. The calculated band gap value is 3.1 eV. The FESEM study shows the spherical morphology and the DLS analysis confirms the particle size is 433 nm. The presence of Ti-O and Zn–O stretching modes are confirmed from Raman spectrum. The electrical properties such as dielectric constant, dielectric loss, and ac conductivity are analysed from impedance data. The prepared multiphase TiO2 (TAB)-ZnO (ZW) nanostructure shows better photocatalytic activity in both UV and visible light region. The rate constant has been calculated as 0.0083 and 0.0052 min-1 for UV and visible light irradiation.