An Alternative Approach to Study Photo-catalytic Behavior of TiO2 Using Synchrotron-Based Advanced Spectroscopic Techniques

Titanium oxide (TiO2)-based nanoparticles have grabbed immense attention for its application as photo-catalyst in numerous fields of research like photo-catalytic treatment of wastewater, water splitting and photo-catalytic degradation of organic pollutants, etc. The current study utilizes synchrotron-based x-ray diffraction (XRD), energy-dispersive Spectroscopy (EDX), high-resolution scanning electron microscopy (HR-SEM), UV-Vis spectroscopy as well as x-ray photo-emission spectroscopy (XPS) and valence band spectroscopy (VBS) technique to unveil the structural, morphological, optical, electronic and magnetic characteristics of TiO2 nanoparticles. The XRD pattern clearly shows the dimorphic nature of TiO2, with coexisting anatase and rutile phases. The Williamson-Hall method suggested that the macro-strain values for the TiO2 sample are similar to 5.201 x 10(- 4). The band gap energies and the excitation wavelength of TiO2 nanoparticles were displayed to be around similar to 3.28 eV and < 400 nm, which suggests that the absorption region is confined to the ultraviolet region. XPS spectra indicated that the Ti existed in dominating 4 + state along with a shoulder peak signifying the 3 + state originating due to the induced oxygen deficiency defect in the given specimen. To get a detailed comprehensive idea of phenomena of photo-catalysis, the most sophisticated tool VBS technique was utilized in current investigation. These measurements suggest that the hybridized state of Ti-3d and O-2p emerges which causes the photo-catalytic activity. To confirm the presence of oxygen vacancies in the TiO2 sample, magnetization measurements were carried out, which demonstrated that TiO2 exhibits super-paramagnetic/ferromagnetic behavior at room temperature.