Mr
Michael Hotz
(Department of Physics, University of Zürich, CH-8057 Zürich, Switzerland)
Cobalt-pyrphyrin (Co-Pyr) is a promising water reduction catalyst. Cu$_2$O(111) and TiO$_2$(110) with monolayer coverage of Co-Pyr were studied for pressures spanning from UHV up to 1mbar of water vapor. Under UV illumination, surface photovoltage shifts of ΔE$_k$=+120meV are observed on Cu$_2$O(111). X-ray absorption spectroscopy of the Co L3-edge was used to monitor the electronic structure of the molecule’s metal center. Comparison to simulated spectra reveals that on TiO$_2$(110), the Co centers partially transform from a +2 to +1 oxidation state upon exposure to water, while on Cu$_2$O(111) they remain in the +2 oxidation state. Our measurements provide insights into properties of Co-Pyr under conditions near those in solar fuel cells.
Mr
Michael Hotz
(Department of Physics, University of Zürich, CH-8057 Zürich, Switzerland)
Mr
Wolf-Dietrich Zabka
(Department of Physics, University of Zürich, CH-8057 Zürich, Switzerland)
Dr
Zbynek Novotny
(Department of Physics, University of Zürich, CH-8057 Zürich, Switzerland)
Dr
Luca Artiglia
(Laboratory of Environmental Chemistry, PSI, CH-5232 Villigen PSI, Switzerland)
Dr
Fabrizio Orlando
(Laboratory of Environmental Chemistry, PSI, CH-5232 Villigen PSI, Switzerland)
Prof.
Markus Ammann
(Laboratory of Environmental Chemistry, PSI, CH-5232 Villigen PSI, Switzerland)
Prof.
Jürg Osterwalder
(Department of Physics, University of Zürich, CH-8057 Zürich, Switzerland)
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