Elucidation of Rh-Induced In-Gap States of Rh:SrTiO3 Visible-Light-Driven Photocatalyst by Soft X-ray Spectroscopy and First-Principles Calculations

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• 作者：Seiji Kawasaki ; Kazuto Akagi ; Kan Nakatsuji ; Susumu Yamamoto ; Iwao Matsuda ; Yoshihisa Harada ; Jun Yoshinobu ; Fumio Komori ; Ryota Takahashi ; Mikk Lippmaa ; Chikako Sakai ; Hideharu Niwa ; Masaharu Oshima ; Katsuya Iwashina ; Akihiko Kudo
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：November 26, 2012
• 年：2012
• 卷：116
• 期：46
• 页码：24445-24448
• 全文大小：296K
• 年卷期：v.116,no.46(November 26, 2012)
• ISSN：1932-7455

文摘

The occupied and unoccupied in-gap electronic states of a Rh-doped SrTiO₃ photocatalyst were investigated by X-ray emission spectroscopy and X-ray absorption spectroscopy for different Rh impurity valence states and doping levels. An unoccupied midgap Rh⁴⁺ acceptor state was found 1.5 eV below the SrTiO₃ conduction band minimum. Both Rh⁴⁺ and Rh³⁺ dopants were found to have an occupied donor level close to the valence band maximum of SrTiO₃. The density of states obtained from first-principles calculations show that all observed spectral features can be assigned to electronic states of substitutional Rh at the Ti site and that Rh:SrTiO₃ is an unusual titanate compound with a characteristic p-type electronic structure. The Rh doping results in a large decrease of the bandgap energy, making Rh:SrTiO₃ an attractive material for use as a visible-light-driven H₂-evolving photocatalyst in a solar water splitting reaction.