Abstract
A flux-matching condition has been applied to determine whether O2 reduction is rate-limiting under photocatalytic conditions for the degradation of CHCl3 at rutile TiO2 single-crystal electrodes. In this approach, the potential dependence of the photooxidation current density is compared to the potential dependence of the current density for O2 reduction. The potential at which the oxidation and reduction fluxes are equal determines the operating potential and the steady-state flux that will flow through the crystal under no applied bias. If this flux-matching condition occurs when the cathodic flux equals the flux of photogenerated carriers, then the predicted quantum yield should approach unity; otherwise, recombination should be significant in the TiO2. Our measurements indicate that significant recombination will occur for the oxidation of typical organic molecules in H2O over a range of pH values. The data also indicate that Pt catalysis of O2 reduction should be beneficial for the oxidation of organic molecules, as would the use of alternate electron acceptors such as Fe(CN)6 3-. The O2 reduction data and rotating disk electrode data collected in this work allow a quantitative comparison to theoretical estimates of the electron transfer rate constant for O2 reduction at TiO2. We also present an elucidation of the previously published theoretical treatments of TiO2 charge transfer rate constants in view of the new data collected herein.
| Original language | English |
|---|---|
| Pages (from-to) | 13385-13395 |
| Number of pages | 11 |
| Journal | Journal of Physical Chemistry |
| Volume | 98 |
| Issue number | 50 |
| Publication status | Published - 1994 |
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ASJC Scopus subject areas
- Physical and Theoretical Chemistry
Cite this
Flux-matching conditions at TiO2 photoelectrodes : Is interfacial electron transfer to O2 rate-limiting in the TiO2-catalyzed photochemical degradation of organics? / Kesselman, Janet M.; Shreve, Gary A.; Hoffmann, Michael R.; Lewis, Nathan S.
In: Journal of Physical Chemistry, Vol. 98, No. 50, 1994, p. 13385-13395.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Flux-matching conditions at TiO2 photoelectrodes
T2 - Is interfacial electron transfer to O2 rate-limiting in the TiO2-catalyzed photochemical degradation of organics?
AU - Kesselman, Janet M.
AU - Shreve, Gary A.
AU - Hoffmann, Michael R.
AU - Lewis, Nathan S
PY - 1994
Y1 - 1994
N2 - A flux-matching condition has been applied to determine whether O2 reduction is rate-limiting under photocatalytic conditions for the degradation of CHCl3 at rutile TiO2 single-crystal electrodes. In this approach, the potential dependence of the photooxidation current density is compared to the potential dependence of the current density for O2 reduction. The potential at which the oxidation and reduction fluxes are equal determines the operating potential and the steady-state flux that will flow through the crystal under no applied bias. If this flux-matching condition occurs when the cathodic flux equals the flux of photogenerated carriers, then the predicted quantum yield should approach unity; otherwise, recombination should be significant in the TiO2. Our measurements indicate that significant recombination will occur for the oxidation of typical organic molecules in H2O over a range of pH values. The data also indicate that Pt catalysis of O2 reduction should be beneficial for the oxidation of organic molecules, as would the use of alternate electron acceptors such as Fe(CN)6 3-. The O2 reduction data and rotating disk electrode data collected in this work allow a quantitative comparison to theoretical estimates of the electron transfer rate constant for O2 reduction at TiO2. We also present an elucidation of the previously published theoretical treatments of TiO2 charge transfer rate constants in view of the new data collected herein.
AB - A flux-matching condition has been applied to determine whether O2 reduction is rate-limiting under photocatalytic conditions for the degradation of CHCl3 at rutile TiO2 single-crystal electrodes. In this approach, the potential dependence of the photooxidation current density is compared to the potential dependence of the current density for O2 reduction. The potential at which the oxidation and reduction fluxes are equal determines the operating potential and the steady-state flux that will flow through the crystal under no applied bias. If this flux-matching condition occurs when the cathodic flux equals the flux of photogenerated carriers, then the predicted quantum yield should approach unity; otherwise, recombination should be significant in the TiO2. Our measurements indicate that significant recombination will occur for the oxidation of typical organic molecules in H2O over a range of pH values. The data also indicate that Pt catalysis of O2 reduction should be beneficial for the oxidation of organic molecules, as would the use of alternate electron acceptors such as Fe(CN)6 3-. The O2 reduction data and rotating disk electrode data collected in this work allow a quantitative comparison to theoretical estimates of the electron transfer rate constant for O2 reduction at TiO2. We also present an elucidation of the previously published theoretical treatments of TiO2 charge transfer rate constants in view of the new data collected herein.
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M3 - Article
VL - 98
SP - 13385
EP - 13395
JO - Journal of Physical Chemistry
JF - Journal of Physical Chemistry
SN - 0022-3654
IS - 50
ER -