TY - JOUR
T1 - Ultrafast Electron Injection Dynamics of Photoanodes for Water-Splitting Dye-Sensitized Photoelectrochemical Cells
AU - Swierk, John R.
AU - McCool, Nicholas S.
AU - Nemes, Coleen T.
AU - Mallouk, Thomas E.
AU - Schmuttenmaer, Charles A.
N1 - Funding Information:
The authors thank Jennifer Gray for her assistance in collecting STEM images and Bangzhi Liu for his help with the ALD experiments. This work was supported by the Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Energy Biosciences, Department of Energy, under Contracts DE-FG02-07ER15911 and DE-FG02-07ER15909 as well as by a generous donation from the TomKat Charitable Trust. N.S.M. thanks the National Science Foundation for support as a graduate fellow under Grant DGE1255832. Instrumentation and facilities used in this project were supported by the Pennsylvania State University Materials Research Institute Nanofabrication Laboratory under National Science Foundation Cooperative Agreement ECS-0335765.
Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/3/24
Y1 - 2016/3/24
N2 - Efficient conversion of solar energy into useful chemical fuels is a major scientific challenge. Water-splitting dye-sensitized photoelectrochemical cells (WS-DSPECs) utilize mesoporous oxide supports sensitized with molecular dyes and catalysts to drive the water-splitting reaction. Despite a growing body of work, the overall efficiencies of WS-DSPECs remain low, in large part because of poor electron injection into the conduction band of the oxide support. In this study, we characterize the ultrafast injection dynamics of several proposed oxide supports (TiO2, TiO2/Al2O3, SnO2, SnO2/TiO2) under identical conditions using time-resolved terahertz spectroscopy. In the absence of an Al2O3 overlayer, we observe a two-step injection from the dye singlet state into nonmobile surface traps, which then relax into the oxide conduction band. We also find that, in SnO2-core/TiO2-shell configurations, electron injection into TiO2 trap states occurs rapidly, followed by trapped electrons being released into SnO2 on the hundreds of picoseconds time scale.
AB - Efficient conversion of solar energy into useful chemical fuels is a major scientific challenge. Water-splitting dye-sensitized photoelectrochemical cells (WS-DSPECs) utilize mesoporous oxide supports sensitized with molecular dyes and catalysts to drive the water-splitting reaction. Despite a growing body of work, the overall efficiencies of WS-DSPECs remain low, in large part because of poor electron injection into the conduction band of the oxide support. In this study, we characterize the ultrafast injection dynamics of several proposed oxide supports (TiO2, TiO2/Al2O3, SnO2, SnO2/TiO2) under identical conditions using time-resolved terahertz spectroscopy. In the absence of an Al2O3 overlayer, we observe a two-step injection from the dye singlet state into nonmobile surface traps, which then relax into the oxide conduction band. We also find that, in SnO2-core/TiO2-shell configurations, electron injection into TiO2 trap states occurs rapidly, followed by trapped electrons being released into SnO2 on the hundreds of picoseconds time scale.
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U2 - 10.1021/acs.jpcc.6b00749
DO - 10.1021/acs.jpcc.6b00749
M3 - Article
AN - SCOPUS:84962197478
SN - 1932-7447
VL - 120
SP - 5940
EP - 5948
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 11
ER -
