Sol-Gel Synthesis of Co2+-Doped TiO2 Nanoparticles and Their Photocatalytic Activity Study

Anatase TiO2 nanoparticles doped with different concentrations of cobalt (0, 1, 2, and 3 mol%) were synthesized by simple sol-gel method at room temperature. The prepared nanoparticles were calcinated at 500 degrees C to get nanocrystalline anatase phase. The crystallite sizes of the doped and undoped TiO2 nanoparticles were estimated with XRD analysis. XRD and XPS analysis revealed the substitutions of the few sites of Ti4+ ions by Co2+ ions. The band gap energy of doped and undoped TiO2 nanoparticles were identified with UV-Vis diffuse reflectance spectra. The band gap energy value of Co-doped TiO2 nanoparticles was observed in the range of 3.2-2.8 eV. The optical absorption edge of doped TiO2 nanoparticles is shifted towards longer wavelength with increase in cobalt content in TiO2 host lattice. The non-spherical morphology of the nanoparticles were confirmed by TEM analysis. The photocatalytic activity tests of the nanoparticles were evaluated by the degradation of aqueous methylene blue (MB) solution.