CaltechAUTHORS
  A Caltech Library Service

Electrochemical Production of Hydroxyl Radical at Polycrystalline Nb-Doped TiO_2 Electrodes and Estimation of the Partitioning between Hydroxyl Radical and Direct Hole Oxidation Pathways

Kesselman, Janet M. and Weres, Oleh and Lewis, Nathan S. and Hoffmann, Michael R. (1997) Electrochemical Production of Hydroxyl Radical at Polycrystalline Nb-Doped TiO_2 Electrodes and Estimation of the Partitioning between Hydroxyl Radical and Direct Hole Oxidation Pathways. Journal of Physical Chemistry B, 101 (14). pp. 2637-2643. ISSN 1520-6106. https://resolver.caltech.edu/CaltechAUTHORS:20150814-081851804

Full text is not posted in this repository. Consult Related URLs below.

Use this Persistent URL to link to this item: https://resolver.caltech.edu/CaltechAUTHORS:20150814-081851804

Abstract

The use of TiO_2 as a photocatalyst for the destruction of organic chemical pollutants in aqueous systems has been extensively studied. One obstacle to the effective utilization of these systems is the relatively inefficient use of the solar spectrum by the photocatalyst. In addition, light delivery to the photocatalyst can be impeded by UV-absorbing components in mixed effluent streams. We present a novel use of TiO_2 as a catalyst for the oxidative degradation of organic compounds in water that uses a potential source instead of light to generate reactive oxidants. Application of an anodic bias of >+2 V vs NHE to titanium electrodes coated with niobium-doped, polycrystalline TiO_2 particles electrochemically generates hydroxyl radicals at the TiO_2 surface. This process has been demonstrated to efficiently degrade a variety of environmentally important pollutants. In addition, these electrodes offer a unique opportunity to probe mechanistic questions in TiO_2 catalysis. By comparing substrate degradation rates with increases in current density upon substrate addition, the extent of degradation due to direct oxidation and •OH oxidation can be quantified. The branching ratio for these two pathways depends on the nature of the organic substrate. Formate is shown to degrade primarily via a hydroxyl radical mechanism at these electrodes, whereas the current increase data for compounds such as 4-chlorocatechol indicate that a higher percentage of their degradation may occur through direct oxidation. In addition, the direct oxidation pathway is shown to be more important for 4-chlorocatechol, a strongly adsorbing substrate, than for 4-chlorophenol, which does not adsorb strongly to TiO_2.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/jp962669rDOIArticle
http://pubs.acs.org/doi/abs/10.1021/jp962669rPublisherArticle
ORCID:
AuthorORCID
Lewis, Nathan S.0000-0001-5245-0538
Hoffmann, Michael R.0000-0001-6495-1946
Additional Information:© 1997 American Chemical Society. Received: August 30, 1996; In Final Form: October 29, 1996. Publication Date (Web): April 3, 1997. We are grateful to DARPA and ONR {NAV 5 HFMN N0001492J1901} for financial support. J. Kesselman acknowledges the NSF for a predoctoral fellowship.
Funders:
Funding AgencyGrant Number
Defense Advanced Research Projects Agency (DARPA)UNSPECIFIED
Office of Naval Research (ONR)NAV 5 HFMN N0001492J1901
NSF Predoctoral FellowshipUNSPECIFIED
Issue or Number:14
Record Number:CaltechAUTHORS:20150814-081851804
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150814-081851804
Official Citation:Electrochemical Production of Hydroxyl Radical at Polycrystalline Nb-Doped TiO2 Electrodes and Estimation of the Partitioning between Hydroxyl Radical and Direct Hole Oxidation Pathways Janet M. Kesselman, Oleh Weres, Nathan S. Lewis, and Michael R. Hoffmann The Journal of Physical Chemistry B 1997 101 (14), 2637-2643 DOI: 10.1021/jp962669r
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59519
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:14 Aug 2015 16:43
Last Modified:03 Mar 2020 13:01

Repository Staff Only: item control page