Synthesis, characterization and high natural sunlight photocatalytic performance of cobalt doped TiO2 nanofibers

Co2+ doped TiO2 nanofibers with different doping percentages were successfully synthesized using a nonaqueous sol–gel method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), x-ray photoelectrons spectroscopy (XPS), FTIR and UV–vis spectroscopy were used to characterize the crystal structures, chemical states, morphologies and photocatalytic properties of Co doped TiO2 nanofibers. Co2+ doping was found to affect the phase transformation from anatase to rutile. Grain growth activation energy of 17.575 kJ/mol was obtained for the TiO2 nanofibers. The photocatalytic activities of the pure and doped nanofibers were investigated with degradation of methyl orange (MO) as a model pollutant. The degradation followed the Langmuir–Hinshelwood (L–H) kinetic model with pseudo-first-order apparent rates of 3.2×10−2, 5.3×10−2, 8.9×10−2 and 7.1×10−2 for Co doped nanofibers of Rt=0.0, 0.0025, 0.005, 0.01 (where Rt is the molar ratio of Co(OAc)2 to Ti(OiPr)4). The result showed that Co2+ doped nanostructure significantly enhanced the photocatalytic degradation of methyl orange under direct sunlight compared to pure TiO2. Rt=0.005 sample showed best sunlight photocatalytic performance among the above samples which is 2.3 times (after 30 min) efficient than that of pure nanostructure.

Graphical abstractNatural sunlight photocatalytic activities of Co2+ doped TiO2 nanofibers were investigated with degradation of MO dye which followed the Langmuir–Hinshelwood (L–H) kinetic model. For Rt=0.005 sample, 99.9% degradation was observed after 75 min irradiation.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Pure and Co2+ doped TiO2 nanofibers (average 30 nm diameter) were synthesized. ► XPS result revealed that Co2+ was incorporated in the TiO2 lattice. ► All samples show excellent sunlight photocatalytic properties. ► Co2+sample show 99.9% degradation of MO after 75 min sunlight irradiation.