Characterization of nanocrystalline cobalt doped TiO2 sol–gel material

Nanocrystalline 1%, 2% and 4% Cobalt-doped TiO2 were prepared by sol–gel technique, followed by freeze-drying treatment at −30 °C temperature for 12 h. The obtained gels were thermally treated at 200, 400, 600 and 800 °C. X-ray Powder Diffraction (XRD), Scanning Electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDAX) were used to study its structural properties. The XRD pattern shows the coexistence of anatase phase and minor brookite phase. UV–vis Spectroscopy and Photoluminescence (PL) were used to study its optical properties. Optical band gap was calculated with the incorporation of different concentrations of cobalt. UV–visible spectroscopy shows variation in band gap for the sample treated at different temperatures for same concentration. All Cobalt doped TiO2 nanostructures show an appearance of Red shift relative to the bulk TiO2. The determination of magnetic properties was also carried out by Gouy balance method.

► Co content increases in TiO2, band gap decreases as Co doping results in localized energy levels just above the valence band.
► Co doped TiO2 indicates red shift in band gap compared to undoped TiO2.
► Co doped TiO2 has strong absorption in visible region so it can be a potential material for photocatalytic activity.
► Co doped TiO2 exhibits paramagnetism at room temperature.