Chapter 13
A Theoretical Study on a Visible-Light
Photo-Catalytic Activity in Carbon-Doped
SrTiO 3 Perovskite
Taku Onishi
Abstract Carbon-doping has been explored to enhance the visible-light photocatalytic activity in SrTiO 3 perovskite. Here, we considered carbon anion (C 2− )-doping
at oxygen site, because no oxygen vacancy is then formed. From our density functional theory (DFT) calculations for carbon anion-doped cluster models, it was
found that carbon anion-doping enhances the visible-light photocatalytic activity,
realizing a stable crystal structure. Finally, we concluded that carbon anion-doped
SrTiO 3 is one of the best visible-light active photocatalysts.
13.1 Introduction
Hydrogen has been considered as one of the next-generation energy resources. Hydrogen is generally produced by steam reforming of natural gas. Recently, it has
been much expected that hydrogen is produced from water splitting by a photocatalyst. Titanium oxides such as SrTiO 3 perovskite [1–3] and TiO 2 [4, 5] have been
widely utilized as photocatalysts. SrTiO 3 has a large bandgap (3.27 eV) [6], corresponding to absorption of ultraviolet (UV) light which is less than 5 % of sunlight.
To use the whole spectrum of sunlight effectively, visible-light active photocatalysts
have been explored.
Previously, we investigated the effect of nitrogen-doping to enhance a visiblelight photocatalytic activity of SrTiO 3 , by the use of molecular orbital (MO) calculation [7–9]. Experimental works reported that nitrogen anion-doping (N 3− ) at
oxygen site realizes the high visible-light photocatalytic activity, as the decreased
bandgap corresponds to visible light region [10, 11]. However, oxygen vacancy is
accompanied by nitrogen-doping, to compensate charge. We concluded that photocatalytic activity becomes inactive, when oxygen vacancy exists in the vicinity of
T. Onishi (B)
Department of Chemistry for Materials, Graduate School of Engineering, Mie University,
1577 Kurimamachiya-cho, Tsu, Mie 517-8507, Japan
e-mail: taku@chem.mie-u.ac.jp
T. Onishi
The Center of Ultimate Technology on Nano-Electronics, Mie University (MIE-CUTE),
1577 Kurimamachiya-cho, Tsu, Mie 517-8507, Japan
M. Hotokka et al. (eds.), Advances in Quantum Methods and Applications in
Chemistry, Physics, and Biology, Progress in Theoretical Chemistry and Physics 27,
DOI 10.1007/978-3-319-01529-3_13,
© Springer International Publishing Switzerland 2013
221
A Theoretical Study on a Visible-Light
Photo-Catalytic Activity in Carbon-Doped
SrTiO 3 Perovskite
Taku Onishi
Abstract Carbon-doping has been explored to enhance the visible-light photocatalytic activity in SrTiO 3 perovskite. Here, we considered carbon anion (C 2− )-doping
at oxygen site, because no oxygen vacancy is then formed. From our density functional theory (DFT) calculations for carbon anion-doped cluster models, it was
found that carbon anion-doping enhances the visible-light photocatalytic activity,
realizing a stable crystal structure. Finally, we concluded that carbon anion-doped
SrTiO 3 is one of the best visible-light active photocatalysts.
13.1 Introduction
Hydrogen has been considered as one of the next-generation energy resources. Hydrogen is generally produced by steam reforming of natural gas. Recently, it has
been much expected that hydrogen is produced from water splitting by a photocatalyst. Titanium oxides such as SrTiO 3 perovskite [1–3] and TiO 2 [4, 5] have been
widely utilized as photocatalysts. SrTiO 3 has a large bandgap (3.27 eV) [6], corresponding to absorption of ultraviolet (UV) light which is less than 5 % of sunlight.
To use the whole spectrum of sunlight effectively, visible-light active photocatalysts
have been explored.
Previously, we investigated the effect of nitrogen-doping to enhance a visiblelight photocatalytic activity of SrTiO 3 , by the use of molecular orbital (MO) calculation [7–9]. Experimental works reported that nitrogen anion-doping (N 3− ) at
oxygen site realizes the high visible-light photocatalytic activity, as the decreased
bandgap corresponds to visible light region [10, 11]. However, oxygen vacancy is
accompanied by nitrogen-doping, to compensate charge. We concluded that photocatalytic activity becomes inactive, when oxygen vacancy exists in the vicinity of
T. Onishi (B)
Department of Chemistry for Materials, Graduate School of Engineering, Mie University,
1577 Kurimamachiya-cho, Tsu, Mie 517-8507, Japan
e-mail: taku@chem.mie-u.ac.jp
T. Onishi
The Center of Ultimate Technology on Nano-Electronics, Mie University (MIE-CUTE),
1577 Kurimamachiya-cho, Tsu, Mie 517-8507, Japan
M. Hotokka et al. (eds.), Advances in Quantum Methods and Applications in
Chemistry, Physics, and Biology, Progress in Theoretical Chemistry and Physics 27,
DOI 10.1007/978-3-319-01529-3_13,
© Springer International Publishing Switzerland 2013
221