Hydrothermal synthesis and photocatalytic activity of anatase TiO2 nanofiber

TiO2 nanofiber consisting of 15 +/- 5 nm anatase grains was synthesized by hydrothermal treatment of fibrous hydrogen titanate precursor at 180 degrees C for 20 h. The hydrogen titanate precursor was synthesized by hydrothermal treatment of commercial P25 TiO2 powder in 10 M NaOH at 200 degrees C for 20 h followed by soaking in 0.1 M HNO3 to perform ion exchange between the as-synthesized Na titanate and H. By controlling pH of the solution during hydrothermal treatment of the hydrogen titanate precursor, pure anatase TiO2 nanofiber was obtained. Its band-gap energy determined from the onset of diffused reflectance spectrum was 3.19 eV which is equal to that of anatase TiO2 powder. The TiO2 nanofiber showed higher photodecomposition efficiency than the Cotiox KA-100 TiO2 but lower than the P25 TiO2. Photodegradation is the predominant process for 'Reactive blue 171' removal.     

Preparation and photocatalytic activity of iron oxide-loaded potassium titanate layered compounds

Iron oxide-loaded hydrous potassium tetratitanate (K0.3Ti4O7.3(OH)1.7) compounds consisting of 1.48 wt% (sample 'B'), 1.87 wt% (sample 'C') and 5.60 wt% (sample 'D') of iron oxide were synthesized by suspending the K0.3Ti4O7.3(OH)1.7 (sample 'A') in Fe2(SO4)3 solution for 24 h, followed by washing several times with deionized water and then dried at 120 degrees C for 24 h. The K0.3Ti4O7.3(OH)1.7 was synthesized by refluxing the K2Ti4O9 x 2H2O in 1 M HNO3 solution. Band-gap energies of the K0.3Ti4O7.3(OH)1.7 and the iron oxide-loaded samples are 3.12 +/- 0.6 eV and 2.23 +/- 0.09 eV, respectively. Photooxidation activity towards methylene blue decomposition under fluorescence irradiation was found to decrease as follow: sample 'B' > sample 'C' > Sample 'A' > sample 'D' > commercial Fe2O3-Blank. The photoactivity under sunlight irradiation was found to decrease as follow: sample 'B' > sample 'A' > Sample 'C' > sample 'D' > commercial Fe2O3-Blank.     

Preparation and photocatalytic study of fibrous K0.3Ti4O7.3(OH)1.7–anatase TiO2 nanocomposite photocatalyst

Nanocomposite of K_0.3Ti₄O_7.3(OH)_1.7 fiber and anatase TiO₂ nanoparticle was prepared by hydrothermal treatment of the K_0.3Ti₄O_7.3(OH)_1.7 which was synthesized by calcination of K₂CO₃ and TiO₂ at 1250 °C followed by refluxing in nitric acid. Effects of hydrothermal treatment conditions such as temperature and time on morphology, phase composition and crystal structure of the nanocomposites were extensively studied. Photocatalytic activities of the catalysts prepared at various hydrothermal conditions were evaluated by means of methylene blue decomposition under blacklight irradiation.