Photoinduced reduction of surface states in Fe:ZnO.

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskrift

Abstract

We report on the electronic structure of nano-crystalline Fe:ZnO, which has recently been found to be an efficient photocatalyst. Using resonant photoemission spectroscopy, we determine the binding energy of Fe 3d states corresponding to different valencies and coordination of the Fe atoms. The photo-activity of ZnO reduces Fe from 3+ to 2+ in the surface region of the nano-crystalline material due to the formation of oxygen vacancies. Electronic states corresponding to low-spin Fe2+ are observed and attributed to crystal field modification at the surface. These states are potentially important for the photocatalytic sensitivity to visible light due to their location deep in the ZnO bandgap. X-ray absorption and x-ray photoemission spectroscopy suggest that Fe is only homogeneously distributed for concentrations up to 3%. Increased concentrations does not result in a higher concentration of Fe ions in the surface region. This is limiting the photocatalytic functionality of ZnO, where the most efficient Fe doping concentration has been shown to be 1%-4%.

Detaljer

Författare
  • R Knut
  • U Lagerqvist
  • P Palmgren
  • Prabir Pal
  • P Svedlindh
  • A Pohl
  • O Karis
Enheter & grupper
Externa organisationer
  • National Physical Laboratory of India
Forskningsområden

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Fysikalisk kemi
Originalspråkengelska
Artikelnummer204703
TidskriftJournal of Chemical Physics
Volym142
Utgivningsnummer20
StatusPublished - 2015
PublikationskategoriForskning
Peer review utfördJa