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Correlating Changes in Electron Lifetime and Mobility on Photocatalytic Activity at Network-Modified TiO2 Aerogels

Title data

DeSario, Paul A. ; Pietron, Jeremy J. ; Taffa, Dereje H. ; Compton, Ryan ; Schünemann, Stefan ; Marschall, Roland ; Brintlinger, Todd H. ; Stroud, Rhonda M. ; Wark, Michael ; Owrutsky, Jeffrey C. ; Rolison, Debra R.:
Correlating Changes in Electron Lifetime and Mobility on Photocatalytic Activity at Network-Modified TiO2 Aerogels.
In: The Journal of Physical Chemistry C. Vol. 119 (6 August 2015) Issue 31 . - pp. 17529-17538.
ISSN 1932-7455
DOI: https://doi.org/10.1021/acs.jpcc.5b04013

Abstract in another language

We use intensity-modulated photovoltage spectroscopy (IMVS) and intensity-modulated photocurrent spectroscopy (IMPS) to characterize carrier dynamics in titania (TiO2) aerogels under photocatalytic conditions. By systematically increasing the weight fraction of the sol?gel precursor during TiO2 sol?gel synthesis, we are able to impart drastic changes in carrier transport/trapping and improve the photocatalytic activity of TiO2 aerogels for two mechanistically divergent photochemical reactions: reductive water splitting (H2 generation) and oxidative degradation of dichloroacetate (DCA). The lifetimes of photogenerated electrons increase in going from lowest-to-highest precursor concentrations, as measured by IMVS, indicating increasing site density for electron traps?a trend that correlates with an 8? improvement for photocatalytic H2 generation. Electron mobility in the aerogel films, as measured by IMPS, decreases with increasing trap density, further implicating the trapping sites as reactive sites. In contrast, photocatalytic DCA degradation?driven primarily by direct hole transfer to adsorbed DCA?depends only weakly on the electron dynamics in the film. Transient infrared spectroscopy shows no difference in carrier decay among the aerogel samples on picosecond time scales, indicating that changes in carrier dynamics within these networked nanomaterials are only observable at time scales measured by IMPV and IMPS. Correlating hole-mediated and electron-mediated photocatalytic activity with direct measurement of electron dynamics under photocatalytically relevant conditions and time scales comprises a powerful approach to determine how synthetic modifications to networked nanostructured photocatalysts affect the relevant physicochemical phenomena underlying their photocatalytic performance.

Further data

Item Type: Article in a journal
Refereed: Yes
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Lehrstuhl Physikalische Chemie III > Lehrstuhl Physikalische Chemie III - Univ.-Prof. Dr. Roland Marschall
Result of work at the UBT: No
DDC Subjects: 500 Science > 540 Chemistry
Date Deposited: 04 Sep 2018 06:14
Last Modified: 30 Oct 2018 07:40
URI: https://eref.uni-bayreuth.de/id/eprint/45669