Exploring Annealing-triggered Phase Transformation, Photoluminescence Quenching, and Synergistic Effects of Co-doped TiO2 Nanoparticles

This study investigates the influence of defects on the electronic, optical, and magnetic properties of tetragonal titanium dioxide (TiO2) and its cobalt-doped variant, Ti0.95Co0.05O2. The research findings of diffraction studies confirms the formation of phases such as anatase, rutile, and their combination within TiO2 nano-structures following annealing. The Debye-Scherrer's rings observed in the selected area electron diffraction patterns and transmission electron microscopy images showed an aggregate of randomly oriented nano-structures. Additionally, elemental analysis confirms the presence of Ti and O as primary constituents. The detailed analysis using microscopy and spectroscopy study identified a high-spin D2h state in Co2+, indicative of lattice defects across the TiO2 nano-structures. A blue shifting in the photoluminescence band gap emission peaks suggested the presence of oxygen vacancy defects in the doped nano-structures. Notably, the increased surface defects and reduced catalyst size promote rapid migration of electron-hole pairs to reaction sites i.e.; on the surface, thereby reducing recombination rates. Ultimately, the study concludes that anatase TiO2, due to its exceptional catalytic performance, is more favourable for applications in photo-catalysis and spintronics than its rutile or mixed-phase counterparts.