Growth, characterization, and electrochemical properties of doped n-Type KTaO3 photoanodes

I. E. Paulauskas, J. E. Katz, G. E. Jellison, N. S. Lewis, L. A. Boatner, G. M. Brown

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

The effects of compositionally induced changes on the semiconducting properties, optical response, chemical stability, and overall performance of KTaO3 photoanodes in photoelectrochemical (PEC) cells have been investigated. Single crystals of n-type Ca- and Ba-doped KTaO3 with carrier concentrations ranging from 0.45 to 11.5 × 1019 cm -3 were grown and characterized as photoanodes in basic aqueous electrolyte PEC cells. The PEC properties of the crystals, including the photocurrent, photovoltage, and flatband potential in contact with 8.5 M NaOH(aq) were relatively independent of whether Ca or Ba was used to produce the semiconducting form of KTaO3. All of the Ca- or Ba-doped KTaO 3 single-crystal photoanodes were chemically stable in the electrolyte and, based on the open-circuit potential and the band-edge positions, were capable of unassisted photochemical H2 and O 2 evolution from H2O. The minority-carrier diffusion lengths values were small and comparable to the depletion region width. Photoanodic currents were only observed for photoanode illumination with light above the bandgap (i.e., λ<340 nm). The maximum external quantum yield occurred at λ=255 nm (4.85 eV), and the depletion width plus the minority-carrier diffusion length ranged from 20 to 65 nm for the various KTaO3 -based photoanode materials.

Original languageEnglish
Pages (from-to)B580-B587
JournalJournal of the Electrochemical Society
Volume156
Issue number5
DOIs
Publication statusPublished - Apr 8 2009

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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