Ultrafast Electron Injection Dynamics of Photoanodes for Water-Splitting Dye-Sensitized Photoelectrochemical Cells

John R. Swierk, Nicholas S. McCool, Coleen T. Nemes, Thomas E. Mallouk, Charles A. Schmuttenmaer

Research output: Contribution to journalArticle

33 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)5940-5948
Number of pages9
JournalJournal of Physical Chemistry C
Volume120
Issue number11
DOIs
StatePublished - Mar 24 2016

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All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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