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Proceedings Paper

A bio-inspired molecular water oxidation catalyst for renewable hydrogen generation: an examination of salt effects
Author(s): Robin Brimblecombe; Miriam Rotstein; Annette Koo; G. Charles Dismukes; Gerhard F. Swiegers; Leone Spiccia
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Paper Abstract

Most transport fuels are derived from fossil fuels, generate greenhouse gases, and consume significant amounts of water in the extraction, purification, and/or burning processes. The generation of hydrogen using solar energy to split water, ideally from abundant water sources such as sea water or other non-potable sources, could potentially provide an unlimited, clean fuel for the future. Solar, electrochemical water splitting typically combines a photoanode at which water oxidation occurs, with a cathode for proton reduction to hydrogen. In recent work, we have found that a bioinspired tetra-manganese cluster catalyzes water oxidation at relatively low overpotentials (0.38 V) when doped into a Nafion proton conduction membrane deposited on a suitable electrode surface, and illuminated with visible light. We report here that this assembly is active in aqueous and organic electrolyte solutions containing a range of different salts in varying concentrations. Similar photocurrents were obtained using electrolytes containing 0.0 - 0.5 M sodium sulfate, sodium perchlorate or sodium chloride. A slight decline in photocurrent was observed for sodium perchlorate but only at and above 5.0 M concentration. In acetonitrile and acetone solutions containing 10% water, increasing the electrolyte concentration was found to result in leaching of the catalytic species from the membrane and a decrease in photocurrent. Leaching was not observed when the system was tested in an ionic liquid containing water, however, a lower photocurrent was generated than observed in aqueous electrolyte. We conclude that immersion of the membrane in an aqueous solution containing an electrolyte concentration of 0.05 - 0.5M represent good conditions for operation for the cubium/Nafion catalytic system.

Paper Details

Date Published: 20 August 2009
PDF: 8 pages
Proc. SPIE 7408, Solar Hydrogen and Nanotechnology IV, 74080V (20 August 2009); doi: 10.1117/12.824840
Show Author Affiliations
Robin Brimblecombe, Monash Univ. (Australia)
Miriam Rotstein, Monash Univ. (Australia)
Annette Koo, Monash Univ. (Australia)
G. Charles Dismukes, Princeton Univ. (United States)
Gerhard F. Swiegers, Univ. of Wollongong (Australia)
Leone Spiccia, Monash Univ. (Australia)

Published in SPIE Proceedings Vol. 7408:
Solar Hydrogen and Nanotechnology IV
Frank E. Osterloh, Editor(s)

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