Photodriven Oxidation of Surface-Bound Iridium-Based Molecular Water-Oxidation Catalysts on Perylene-3,4-dicarboximide-Sensitized TiO2 Electrodes Protected by an Al2O3 Layer

Rebecca J. Kamire, Kelly L. Materna, William L. Hoffeditz, Brian T. Phelan, Julianne M. Thomsen, Omar K. Farha, Joseph T. Hupp, Gary W. Brudvig, Michael R. Wasielewski

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Improving stability and slowing charge recombination are some of the greatest challenges in the development of dye-sensitized photoelectrochemical cells (DSPECs) for solar fuels production. We have investigated the effect of encasing dye molecules in varying thicknesses of Al2O3 deposited by atomic layer deposition (ALD) before catalyst loading on both the stability and the charge transfer dynamics in organic dye-sensitized TiO2 photoanodes containing iridium-based molecular water-oxidation catalysts. In the TiO2|dye|Al2O3|catalyst electrodes, a sufficiently thick ALD layer protects the perylene-3,4-dicarboximide (PMI) chromophores from degradation over several weeks of exposure to light. The insulating capacity of the layer allows a higher photocurrent in the presence of ALD while initial charge injection is slowed by only 1.6 times, as observed by femtosecond transient absorption spectroscopy. Rapid picosecond-scale catalyst oxidation is observed in the presence of a dinuclear catalyst, IrIr, but is slowed to tens of picoseconds for a mononuclear catalyst, IrSil, that incorporates a long linker. Photoelectrochemical experiments demonstrate higher photocurrents with IrSil compared to IrIr, which show that recombination is slower for IrSil, while higher photocurrents with IrIr upon addition of ALD layers confirm that ALD successfully slows charge recombination. These findings demonstrate that, beyond stability improvements, ALD can contribute to tuning charge transfer dynamics in photoanodes for solar fuels production and may be particularly useful for slowing charge recombination and accounting for varying charge transfer rates based on the molecular structures of incorporated catalysts. (Chemical Equation Presented).

Original languageEnglish
Pages (from-to)3752-3764
Number of pages13
JournalJournal of Physical Chemistry C
Volume121
Issue number7
DOIs
Publication statusPublished - Feb 23 2017

Fingerprint

Perylene
Iridium
iridium
Atomic layer deposition
atomic layer epitaxy
catalysts
Oxidation
oxidation
Electrodes
Catalysts
electrodes
Water
water
Coloring Agents
Dyes
fuel production
dyes
Photocurrents
photocurrents
Charge transfer

ASJC Scopus subject areas

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

Cite this

Photodriven Oxidation of Surface-Bound Iridium-Based Molecular Water-Oxidation Catalysts on Perylene-3,4-dicarboximide-Sensitized TiO2 Electrodes Protected by an Al2O3 Layer. / Kamire, Rebecca J.; Materna, Kelly L.; Hoffeditz, William L.; Phelan, Brian T.; Thomsen, Julianne M.; Farha, Omar K.; Hupp, Joseph T.; Brudvig, Gary W.; Wasielewski, Michael R.

In: Journal of Physical Chemistry C, Vol. 121, No. 7, 23.02.2017, p. 3752-3764.

Research output: Contribution to journalArticle

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