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Title: Inner Layer Control of Performance in a Dye-Sensitized Photoelectrosynthesis Cell

Authors:
 [1];  [1];  [1];  [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Solar Fuels (UNC EFRC)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1388204
DOE Contract Number:
SC0001011
Resource Type:
Journal Article
Resource Relation:
Journal Name: ACS Applied Materials and Interfaces; Journal Volume: 9; Journal Issue: 39; Related Information: 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:
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)

Citation Formats

Wang, Degao, Farnum, Byron H., Sheridan, Matthew V., Marquard, Seth L., Sherman, Benjamin D., and Meyer, Thomas J. Inner Layer Control of Performance in a Dye-Sensitized Photoelectrosynthesis Cell. United States: N. p., 2017. Web. doi:10.1021/acsami.7b00225.
Wang, Degao, Farnum, Byron H., Sheridan, Matthew V., Marquard, Seth L., Sherman, Benjamin D., & Meyer, Thomas J. Inner Layer Control of Performance in a Dye-Sensitized Photoelectrosynthesis Cell. United States. doi:10.1021/acsami.7b00225.
Wang, Degao, Farnum, Byron H., Sheridan, Matthew V., Marquard, Seth L., Sherman, Benjamin D., and Meyer, Thomas J. Thu . "Inner Layer Control of Performance in a Dye-Sensitized Photoelectrosynthesis Cell". United States. doi:10.1021/acsami.7b00225.
@article{osti_1388204,
title = {Inner Layer Control of Performance in a Dye-Sensitized Photoelectrosynthesis Cell},
author = {Wang, Degao and Farnum, Byron H. and Sheridan, Matthew V. and Marquard, Seth L. and Sherman, Benjamin D. and Meyer, Thomas J.},
abstractNote = {},
doi = {10.1021/acsami.7b00225},
journal = {ACS Applied Materials and Interfaces},
number = 39,
volume = 9,
place = {United States},
year = {Thu Mar 02 00:00:00 EST 2017},
month = {Thu Mar 02 00:00:00 EST 2017}
}
  • In a Dye Sensitized Photoelectrosynthesis Cell (DSPEC) the relative orientation of catalyst and chromophore play important roles. Here we introduce a new, robust, Atomic Layer Deposition (ALD) procedure for the preparation of assemblies on wide bandgap semiconductors. In the procedure, phosphonated metal complex precursors react with metal ion bridging to an external chromophore or catalyst to give assemblies bridged by Al(III), Sn(IV), Ti(IV), or Zr(IV) metal oxide units as bridges. The procedure has been extended to chromophore-catalyst assemblies for water oxidation catalysis. A SnO2 bridged assembly on SnO2/TiO2 core/shell electrodes undergoes water splitting with an incident photon conversion efficiency (IPCE)more » of 17.1% at 440 nm. Reduction of water at a Ni(II)-based catalyst on NiO films has been shown to give H2. Compared to conventional solution-based procedures, the ALD approach offers significant advantages in scope and flexibility for the preparation of stable surface structures.« less
  • Nanosecond laser flash photolysis and photocurrent measurements have been used to investigate use of [Ru(bpy) 2((4,4'-PO 3H 2) 2bpy)] 2+ attached to TiO 2 nanoparticle films, TiO 2-Ru II, in a dye-sensitized photoelectrosynthesis cell (DSPEC) configuration for H 2 production. In these experiments, laser flash excitation of TiO 2-Ru II and rapid injection lead to TiO 2(e -)-Ru III with subsequent TiO 2(e -)-Ru III → TiO 2-Ru II back electron transfer monitored on the nsec time scale with and without added triethanolamine (TEOA) and deprotonated ethylenediaminetetraacetic tetra-anion (EDTA 4-) as irreversible electron transfer donors. With added TEOA or EDTAmore » 4-, a competition exists between back electron transfer and scavenger oxidation with the latter leading to H 2 production in the photoelectrosynthesis cell. Reduction of TiO 2(e -)-Ru III by both TEOA and EDTA 4- occurs with k D ~ 10 6 M -1 s -1. EDTA 4- is a more efficient scavenger by a factor of ~3 because of a more favorable partition equilibrium between the film and the external solution. Its increased scavenger efficiency appears in incident photon-to-current conversion efficiency (IPCE) measurements, in electron collection efficiencies (η coll), and in photocurrent measurements with H 2 production. Evaluation of electron collection efficiencies by transient current measurements gave η coll ~ 24% for TEOA and ~ 70% for EDTA 4-. The dynamics of back electron transfer are minimized, and collection efficiencies, photocurrents, and hydrogen production are maximized by application of a positive applied bias consistent with the results of I-V measurements. A pH dependent plateau is reached at ~0 V at pH = 4.5 (EDTA 4-) and at ~ -0.4 V at pH 6.7 (TEOA). The difference is qualitatively consistent with the influence of pH on electron population in trap states below the conduction band and the role they play in back electron transfer. The excitation dependence of IPCE measurements matches the spectrum of TiO 2-Ru II with IPCE values ~3 times higher for EDTA 4- than for TEOA as noted above. Absorbed photon-to-current efficiency (APCE) values are light-intensity dependent because of the effect of multiple injection events and the influence of increasing trap site electron densities on back electron transfer. The key to efficient H 2 production is minimizing back electron transfer. Application of a sufficiently positive potential relative to E CB for TiO 2 accelerates loss of electrons from the film in competition with back electron transfer allowing for H 2 production with efficiencies approaching 14.7% under steady-state irradiation.« less