Exploring annealing-triggered phase transformation, photoluminescence quenching, and synergistic effects of Co-doped TiO 2 nanoparticles

This study investigates the influence of defects on the electronic, optical, and magnetic properties of tetragonal titanium dioxide (TiO 2 ) and its cobalt-doped variant, Ti 0.95 Co 0.05 O 2 . The research findings of diffraction studies confirms the formation of phases such as anatase, rutile, and their combination within TiO 2 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 D 2h state in Co 2 + , indicative of lattice defects across the TiO 2 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 TiO 2 , due to its exceptional catalytic performance, is more favourable for applications in photo-catalysis and spintronics than its rutile or mixed-phase counterparts.