title: Surface aspects of sol-gel derived hematite films for the photoelectrochemical oxidation of water.
abstract: α-Fe(2)O(3) (hematite) photoanodes for the oxygen evolution reaction (OER) were prepared by a cost-efficient sol-gel procedure. Due to low active photoelectrochemical properties observed, it is assumed that the sol-gel procedure leads to hematite films with defects and surface states on which generated charge carriers are recombined or immobilized in trap processes. Electrochemical activation was proven to diminish unfavourable surface groups to some extent. More efficiently, a plasma treatment improves significantly the photoelectrochemical properties of the OER. X-ray photoelectron spectroscopy (XPS) analysis reveals an oxygen enriched surface layer with new oxygen species which may be responsible for the improved electrochemical activity. Due to surface photovoltage an increased fraction of transferred charge carriers from these newly produced surface defects are identified.
authors.affiliation: Helmholtz-Zentrum Geesthacht, Institute for Materials Research, Materials Technology (WTE), Max-Planck-Str. 1, 21502 Geesthacht, Germany. iris.herrmann-geppert@hzg.de
authors.forename: Iris
authors.initials: I
authors.lastname: Herrmann-Geppert
authors.forename: Peter
authors.initials: P
authors.lastname: Bogdanoff
authors.forename: Jörg
authors.initials: J
authors.lastname: Radnik
authors.forename: Steffen
authors.initials: S
authors.lastname: Fengler
authors.forename: Thomas
authors.initials: T
authors.lastname: Dittrich
authors.forename: Sebastian
authors.initials: S
authors.lastname: Fiechter
mesh_terms: D055664:Electrochemical Techniques; D005290:Ferric Compounds / Q000737:chemistry*; D005782:Gels / Q000737:chemistry*; D008027:Light; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D005290:Ferric Compounds; D005782:Gels; D014867:Water; C000499:ferric oxide; D010100:Oxygen