Observation and alteration of surface states of hematite photoelectrodes

Chun Du, Ming Zhang, Ji Wook Jang, Yang Liu, Gang-yu Liu, Dunwei Wang

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

Hematite prepared by atomic layer deposition (ALD) was found to exhibit photocurrents when illuminated by near-infrared light (λ = 830 nm), whose energy is smaller than the band gap of hematite. The phenomenon was inferred to be a result of valence band to surface state transition. The influence of surface states on the thermodynamics of the hematite/water interface was studied under open-circuit conditions. It was discovered that the equilibrium potential of the hematite surface was more negative than water oxidation potential by at least 0.4 V. With a NiFeOx coating by photochemical decomposition of organometallic precursors, the equilibrium potential of hematite was restored to water oxidation potential, and the photoresponse under 830 nm illumination was annihilated. Therefore, the states were rationalized by the chemical status at the electrode surfaces, and this hypothesis was supported by similar observations on other metal oxide electrodes such as TiO2.

Original languageEnglish (US)
Pages (from-to)17054-17059
Number of pages6
JournalJournal of Physical Chemistry C
Volume118
Issue number30
DOIs
StatePublished - Jul 31 2014

Fingerprint

Hematite
Surface states
hematite
Water
water
Oxidation
oxidation
Electrodes
electrodes
Atomic layer deposition
Organometallics
atomic layer epitaxy
Electron transitions
Valence bands
Photocurrents
Oxides
metal oxides
photocurrents
Energy gap
Lighting

ASJC Scopus subject areas

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

Cite this

Observation and alteration of surface states of hematite photoelectrodes. / Du, Chun; Zhang, Ming; Jang, Ji Wook; Liu, Yang; Liu, Gang-yu; Wang, Dunwei.

In: Journal of Physical Chemistry C, Vol. 118, No. 30, 31.07.2014, p. 17054-17059.

Research output: Contribution to journalArticle

Du, Chun ; Zhang, Ming ; Jang, Ji Wook ; Liu, Yang ; Liu, Gang-yu ; Wang, Dunwei. / Observation and alteration of surface states of hematite photoelectrodes. In: Journal of Physical Chemistry C. 2014 ; Vol. 118, No. 30. pp. 17054-17059.
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