A comparison of the photocatalytic activity of six tunneled titanates

作者：Sanford Stephen; Misture Scott T; Edwards Doreen D^*

来源：Journal of Solid State Chemistry, 2013, 200: 189-196.

DOI：10.1016/j.jssc.2012.12.036

• Gallium titanium oxide
• Tunneled titanate
• Beta-gallia rutile intergrowths
• Hollandite
• 1-dimensional tunnel

The photocatalytic behavior of six tunneled titanates-Na0.7Ga4.7Ti0.3O8, Na0.8Ga4.8Ti1.2O10, Na0.8Ga4.8-Ti2.2O12, K1Ga17Ti15O56, K1.5Ga1.5Ti6.5O16, and BaTi4O6-was investigated using methylene blue as an indicator and a xenon arc lamp as the radiation source. Powders prepared by solid state reaction had surface areas ranging from 0.40 to 1.58 m(2)/g and particle sizes ranging from 1 to 25 mu m. Bandgaps, as measured from diffuse reflectance data, ranged from 2.84 to 4.15 eV. Two of the tunneled titanates-Na0.8Ga4.8Ti1.2O10 and Na0.7Ga4.7Ti0.3O8-exhibited negligible photocatalytic activity. The activities of Na0.8Ga4.8Ti2.2O12, KGa17Ti15O56, and K1.5Ga1.5Ti6.5O16 were similar to each other, exhibiting apparent first-order reaction rates of 0.275 to 0.31 h(-1) using 100 mg of powder in 125 ml of 20 mu M methylene blue at room temperature. The BaTi4O9 sample exhibited the highest photocatalytic activity with an apparent first-order reaction rate of 0.53 h(-1) under the same conditions. The addition of a RuO2 co-catalyst improved the photocatalytic activity of Na0.7Ga4.7Ti0.3O8, decreased the activity of BaTi4O9, and had little effect on the activity of the other powders. A comparison of the structural features in the six materials shows that photocatalytic activity is strongly related to the density of TiO6 octahedra in the different crystal structures. Among the gallium-containing tunneled titanates, photocatalytic activity increased with decreasing band gap.

• 出版日期2013-4