Elucidation of Rh-induced In-gap states of Rh:SrTiO3 visible-light-driven photocatalyst by soft X-ray spectroscopy and first-principles calculations

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

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61 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)24445-24448
Number of pages4
JournalJournal of Physical Chemistry C
Volume116
Issue number46
DOIs
Publication statusPublished - 2012

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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