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The Role of Surface States in the Oxygen Evolution Reaction on Hematite
Author(s) -
Iandolo Beniamino,
Hellman Anders
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201406800
Subject(s) - hematite , oxygen evolution , water splitting , surface states , dielectric spectroscopy , chemistry , chemical physics , photoelectrochemistry , oxygen , semiconductor , materials science , surface (topology) , mineralogy , photocatalysis , catalysis , electrochemistry , electrode , optoelectronics , biochemistry , geometry , mathematics , organic chemistry
Hematite (α‐Fe 2 O 3 ) is an extensively investigated semiconductor for photoelectrochemical (PEC) water splitting. The nature and role of surface states on the oxygen evolution reaction (OER) remain however elusive. First‐principles calculations were used to investigate surface states on hematite under photoelectrochemical conditions. The density of states for two relevant hematite terminations was calculated, and in both cases the presence and the role of surface states was rationalized. Calculations also predicted a Nerstian dependence on the OER onset potential on pH, which was to a very good extent confirmed by PEC measurements on hematite model photoanodes. Impedance spectroscopy characterization confirmed that the OER takes place via the same surface states irrespective of pH. These results provide a framework for a deeper understanding of the OER when it takes place via surface states.