TY - JOUR
T1 - pH-dependent redox potential induced in a sensitizing dye by adsorption onto TiO2
AU - Zaban, Arie
AU - Ferrere, Suzanne
AU - Sprague, Julian
AU - Gregg, Brian A.
PY - 1997/1/2
Y1 - 1997/1/2
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0031546403&partnerID=8YFLogxK
U2 - 10.1021/jp962252l
DO - 10.1021/jp962252l
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AN - SCOPUS:0031546403
SN - 1520-6106
VL - 101
SP - 55
EP - 57
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 1
ER -