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

被引:96
作者
Ji, SM
Borse, PH
Kim, HG
Hwang, DW
Jang, JS
Bae, SW
Lee, JS
机构
[1] Pohang Univ Sci & Technol, Dept Chem Engn, Pohang 790784, South Korea
[2] Pohang Univ Sci & Technol, Sch Environm Sci & Engn, Pohang 790784, South Korea
[3] Samsung Elect Corp Ltd, Mfg Technol Team, Kyunggido, South Korea
关键词
D O I
10.1039/b417052k
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
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 methanol - water 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, N2p orbital was the main contributor to the top of the valence band, causing band gap narrowing while the bottom of conduction band due to Nb4d orbital remained almost unchanged.
引用
收藏
页码:1315 / 1321
页数:7
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