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Title: Visible photoelectrochemical water splitting into H2 and O2 in a dye-sensitized photoelectrosynthesis cell

A hybrid strategy for solar water splitting is exploited here based on a dye-sensitized photoelectrosynthesis cell (DSPEC) with a mesoporous SnO2/TiO2 core/shell nanostructured electrode derivatized with a surface-bound Ru(II) polypyridyl-based chromophore–catalyst assembly. The assembly, [(4,4’-(PO3H2)2bpy)2Ru(4-Mebpy-4’-bimpy)Ru(tpy)(OH2)]4+ ([RuaII-RubII-OH2]4+, combines both a light absorber and a water oxidation catalyst in a single molecule. It was attached to the TiO2 shell by phosphonate-surface oxide binding. The oxide-bound assembly was further stabilized on the surface by atomic layer deposition (ALD) of either Al2O3 or TiO2 overlayers. Illumination of the resulting fluorine-doped tin oxide (FTO)|SnO2/TiO2|-[RuaII-RubII-OH2]4+(Al2O3 or TiO2) photoanodes in photoelectrochemical cells with a Pt cathode and a small applied bias resulted in visible-light water splitting as shown by direct measurements of both evolved H2 and O2. The performance of the resulting DSPECs varies with shell thickness and the nature and extent of the oxide overlayer. Use of the SnO2/TiO2 core/shell compared with nanoITO/TiO2 with the same assembly results in photocurrent enhancements of ~5. In conclusion, systematic variations in shell thickness and ALD overlayer lead to photocurrent densities as high as 1.97 mA/cm2 with 445-nm, ~90-mW/cm2 illumination in a phosphate buffer at pH 7.
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [1]
  1. Univ. of North Carolina, Chapel Hill, NC (United States). Dept. of Chemistry
  2. Univ. of Washington, Seattle, WA (United States). Dept. of Chemistry
Publication Date:
OSTI Identifier:
1210802
Grant/Contract Number:
SC0001011
Type:
Accepted Manuscript
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 112; Journal Issue: 19; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Research Org:
Energy Frontier Research Centers (EFRC). Center for Solar Fuels (UNC EFRC)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Contributing Orgs:
UNC partners with University of North Carolina (lead); Duke University; University of Florida; Georgia Institute of Technology; University; North Carolina Central University; Research Triangle Institute
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; catalysis (homogeneous), catalysis (heterogeneous), solar (photovoltaic), solar (fuels), photosynthesis (natural and artificial), hydrogen and fuel cells, electrodes - solar, charge transport, materials and chemistry by design, synthesis (novel materials), synthesis (self-assembly)