Jump to main content
Jump to site search

Issue 5, 2013
Previous Article Next Article

Formation of an electron hole doped film in the α-Fe2O3 photoanode upon electrochemical oxidation

Author affiliations

Abstract

Solar hydrogen generation by water splitting in photoelectrochemical cells (PEC) is an appealing technology for a future hydrogen economy. Hematite is a prospective photoanode material in this respect because of its visible light conjugated band gap, its corrosion stability, its environmentally benign nature and its low cost. Its bulk and surface electronic structure has been under scrutiny for many decades and is considered critical for improvement of efficiency. In the present study, hematite films of nominally 500 nm thickness were obtained by dip-coating on fluorine doped tin oxide (FTO) glass slides and then anodised in 1 molar KOH at 500, 600, and 700 mV for 1, 10, 120 and 1440 minutes under dark conditions. X-ray photoelectron spectra recorded at the Fe 3p resonant absorption threshold show that the eg transition before the Fermi energy, which is well developed in the pristine hematite film, becomes depleted upon anodisation. The spectral weight of the eg peak decreases with the square-root of the anodisation time, pointing to a diffusion controlled process. The speed of this process increases with the anodisation potential, pointing to Arrhenius behaviour. Concomitantly, the weakly developed t2g peak intensity becomes enhanced in the same manner. This suggests that the surface of the photoanode contains Fe2+ species which become oxidized toward Fe3+ during anodisation. The kinetic behaviour derived from the experimental data suggests that the anodisation forms an electron hole doped film on and below the hematite surface.

Graphical abstract: Formation of an electron hole doped film in the α-Fe2O3 photoanode upon electrochemical oxidation

Back to tab navigation

Supplementary files

Publication details

The article was received on 27 Jul 2012, accepted on 08 Oct 2012 and first published on 09 Oct 2012


Article type: Paper
DOI: 10.1039/C2CP42597A
Citation: Phys. Chem. Chem. Phys., 2013,15, 1443-1451
  •   Request permissions

    Formation of an electron hole doped film in the α-Fe2O3 photoanode upon electrochemical oxidation

    K. Gajda-Schrantz, S. Tymen, F. Boudoire, R. Toth, D. K. Bora, W. Calvet, M. Grätzel, E. C. Constable and A. Braun, Phys. Chem. Chem. Phys., 2013, 15, 1443
    DOI: 10.1039/C2CP42597A

Search articles by author

Spotlight

Advertisements