pH-dependent redox potential induced in a sensitizing dye by adsorption onto TiO2

Arie Zaban, Suzanne Ferrere, Julian Sprague, Brian A. Gregg

Research output: Contribution to journalArticlepeer-review

182 Scopus citations


The oxidation potential of a ruthenium(II)-polypyridine sensitizing dye is independent of pH when the dye is dissolved in solution. However, when the dye is adsorbed onto nanocrystalline TiO2, its oxidation potential becomes pH-dependent, decreasing 53 mV per unit pH. This is approximately the same pH-dependence as followed by the flatband potential of the TiO2. Therefore, the driving forces for both forward and back electron transfer reactions are practically independent of pH. This may explain the pH-independent rate of back electron transfer recently observed by Yan and Hupp (J. Phys. Chem. 1996, 100, 6867). To our knowledge, the induction of a pH-dependent redox potential upon adsorption of an otherwise pH-independent dye has not been previously reported.

Original languageEnglish
Pages (from-to)55-57
Number of pages3
JournalJournal of Physical Chemistry B
Issue number1
StatePublished - 2 Jan 1997
Externally publishedYes


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