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Issue 6, 2005
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Photocatalytic hydrogen production from watermethanol mixtures using N-doped Sr2Nb2O7 under visible light irradiation: effects of catalyst structure

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Abstract

Nitrogen-doped perovskite type materials, Sr2Nb2O7−xNx (0, 1.5 < x < 2.8), have been studied as visible light-active photocatalysts for hydrogen production from methanolwater mixtures. Nitrogen doping in Sr2Nb2O7 red-shifted the light absorption edge into the visible light range and induced visible light photocatalytic activity. There existed an optimum amount of nitrogen doping that showed the maximum rate of hydrogen production. Among the potential variables that might cause this activity variation, the crystal structure appeared to be the most important. Thus, as the extent of N-doping increased, the original orthorhombic structure of the layered perovskite was transformed into an unlayered cubic oxynitride structure. The most active catalytic phase was an intermediate phase still maintaining the original layered perovskite structure, but with a part of its oxygen replaced by nitrogen and oxygen vacancy to adjust the charge difference between oxygen and doped nitrogen. These experimental observations were explained by density functional theory calculations. Thus, in Sr2Nb2O7−xNx, N 2p orbital was the main contributor to the top of the valence band, causing band gap narrowing while the bottom of conduction band due to Nb 4d orbital remained almost unchanged.

Graphical abstract: Photocatalytic hydrogen production from water–methanol mixtures using N-doped Sr2Nb2O7 under visible light irradiation: effects of catalyst structure

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Publication details

The article was received on 08 Nov 2004, accepted on 07 Feb 2005 and first published on 16 Feb 2005


Article type: Paper
DOI: 10.1039/B417052K
Citation: Phys. Chem. Chem. Phys., 2005,7, 1315-1321
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    Photocatalytic hydrogen production from watermethanol mixtures using N-doped Sr2Nb2O7 under visible light irradiation: effects of catalyst structure

    S. Min Ji, P. H. Borse, H. Gyu Kim, D. Won Hwang, J. Suk Jang, S. Won Bae and J. Sung Lee, Phys. Chem. Chem. Phys., 2005, 7, 1315
    DOI: 10.1039/B417052K

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