Influence of the Reduction Temperature of TiO2/rGO Nanotubes on the Structural Defects Studied by Raman Spectroscopy

Abstract

Titanium oxide (TiO2) is an excellent photocatalyst, under ultraviolet light irradiation, for the degradation of various organic pollutants. However, TiO₂ is limited by its high band gap value (3.2 eV). To overcome this limitation, graphene oxide (GO) and its derivatives, with their high specific surface area and excellent light absorption properties, can enhance the efficiency of the photocatalytic properties of TiO₂ nanotubes. In this study, a material with potential use in photocatalysis was prepared by thermally incorporating GO into titanium oxide nanotubes (TiO₂NTs) using dip-coating deposition. The samples were characterized by Raman spectroscopy, field emission gun scanning electron microscopy (FEG-SEM), Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analysis/differential scanning calorimetry/differential thermogravimetry (TGA/DSC/DTG) GA/DSC/DTG and UV–Vis spectroscopy. These techniques allowed for the observation of the effect of thermal treatment on the nanocomposite. It was determined that the optimum temperature for the thermal treatment of the TiO₂NTs/GO nanocomposite is 420 °C, evidenced by the analyzed Raman parameters (G-band, FWHM, I_D/I_G, distance between defects—L_D and G-band position), which are consistent with a material that has few defects (increased L_D). Furthermore, the characterizations demonstrated the satisfactory formation of a reduction of functional groups for the formation of uniform TiO₂/rGO nanotubes, decrease in the edge defects of GO, tuning of the diameter TiO₂ and confirming the efficiency of the synthesis process of these nanostructures. Finally, the results are promising for potential applications in devices for photocatalysis and CO₂ storage.