Photoelectrochemistry of nickel(II) oxide

M. P. Dare-Edwards, John B Goodenough, A. Hamnett, N. D. Nicholson

Research output: Contribution to journalArticle

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Abstract

The electrochemistry and photoelectrochemistry of a (110) face of single-crystal lithiated NiO has been studied. The Mott-Schottky and photocurrent appearance potential suggest a flat-band potential of +0.8 V (NHE), and earlier capacitance data are used to fix a second acceptor level at +0.4 eV above the Li acceptor states. A simple geometrical interpretation of the anodic transients at 0.95 and 1.30 V (NHE) is provided, and the Tafel slope observed at anodic potentials is shown to be consistent with an electrochemical process having charge transfer as a rate-determining step. The optical data are interpreted with an energy-level scheme using a value of ca. 3 eV for the Hubbard parameter U defining the correlation splitting of the Ni 3d8 and Ni 3d9 configurations, and the data are consistent with a direct allowed transition at the band edge that is assigned to O 2p6 → Ni 3d9. Comparison with the X.p.e.s. spectrum and the known position of the O 2p6 band edge in other transition-metal oxides leads to a suggested Ni 3d8-O 2p6 band-edge separation of ca. 1.4 eV. The very low efficiencies found for NiO can be understood only if the minority-carrier diffusion length becomes comparable with the semiconductor Debye length. The very low ratio of free carriers to trapped holes in NiO is shown to make this material impractical for solar-energy devices.

Original languageEnglish (US)
Pages (from-to)643-661
Number of pages19
JournalJournal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics
Volume77
Issue number4
DOIs
StatePublished - Dec 1 1981

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photoelectrochemistry
Electrochemistry
Photocurrents
Solar energy
Electron energy levels
Transition metals
Charge transfer
Capacitance
Single crystals
nickel
Semiconductor materials
oxides
Debye length
solar energy
electrochemistry
diffusion length
minority carriers
fixing
metal oxides
photocurrents

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Physical and Theoretical Chemistry

Cite this

Photoelectrochemistry of nickel(II) oxide. / Dare-Edwards, M. P.; Goodenough, John B; Hamnett, A.; Nicholson, N. D.

In: Journal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics, Vol. 77, No. 4, 01.12.1981, p. 643-661.

Research output: Contribution to journalArticle

Dare-Edwards, M. P. ; Goodenough, John B ; Hamnett, A. ; Nicholson, N. D. / Photoelectrochemistry of nickel(II) oxide. In: Journal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics. 1981 ; Vol. 77, No. 4. pp. 643-661.
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