A comparison of the photocatalytic activity of six tunneled titanates
- Inamori School of Engineering, Alfred University, Alfred, NY 14802 (United States)
The photocatalytic behavior of six tunneled titanates—Na{sub 0.7}Ga{sub 4.7}Ti{sub 0.3}O{sub 8}, Na{sub 0.8}Ga{sub 4.8}Ti{sub 1.2}O{sub 10}, Na{sub 0.8}Ga{sub 4.8}Ti{sub 2.2}O{sub 12}, K{sub 1}Ga{sub 17}Ti{sub 15}O{sub 56}, K{sub 1.5}Ga{sub 1.5}Ti{sub 6.5}O{sub 16}, and BaTi{sub 4}O{sub 9}—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{sup 2}/g and particle sizes ranging from 1 to 25 μm. Bandgaps, as measured from diffuse reflectance data, ranged from 2.84 to 4.15 eV. Two of the tunneled titanates—Na{sub 0.8}Ga{sub 4.8}Ti{sub 1.2}O{sub 10} and Na{sub 0.7}Ga{sub 4.7}Ti{sub 0.3}O{sub 8}—exhibited negligible photocatalytic activity. The activities of Na{sub 0.8}Ga{sub 4.8}Ti{sub 2.2}O{sub 12}, KGa{sub 17}Ti{sub 15}O{sub 56}, and K{sub 1.5}Ga{sub 1.5}Ti{sub 6.5}O{sub 16} were similar to each other, exhibiting apparent first-order reaction rates of 0.275 to 0.31 h{sup −1} using 100 mg of powder in 125 ml of 20 μM methylene blue at room temperature. The BaTi{sub 4}O{sub 9} sample exhibited the highest photocatalytic activity with an apparent first-order reaction rate of 0.53 h{sup −1} under the same conditions. The addition of a RuO{sub 2} co-catalyst improved the photocatalytic activity of Na{sub 0.7}Ga{sub 4.7}Ti{sub 0.3}O{sub 8}, decreased the activity of BaTi{sub 4}O{sub 9}, 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 TiO{sub 6} octahedra in the different crystal structures. Among the gallium-containing tunneled titanates, photocatalytic activity increased with decreasing band gap. - Graphical abstract: Na{sub 0.7}Ga{sub 4.7}Ti{sub 0.3}O{sub 8}—One of the tunneled titanates investigated. Highlights: ► The photocatalytic activity of six tunneled titanates was compared. ► Na{sub 0.8}Ga{sub 4.8}Ti{sub 1.2}O{sub 10} and Na{sub 0.7}Ga{sub 4.7}Ti{sub 0.3}O{sub 8} exhibited negligible photocatalytic activity. ► The activities of Na{sub 0.8}Ga{sub 4.8}Ti{sub 2.2}O{sub 12}, KGa{sub 17}Ti{sub 15}O{sub 56}, and K{sub 1.5}Ga{sub 1.5}Ti{sub 6.5}O{sub 16} were similar to each other. ► BaTi{sub 4}O{sub 9} exhibited the highest photocatalytic activity. ► Photocatalytic activity is related to the density of TiO{sub 6} octahedra.
- OSTI ID:
- 22304551
- Journal Information:
- Journal of Solid State Chemistry, Vol. 200; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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