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Evaluating the Mechanism of Visible Light Activity for N,F-TiO2Using Photoelectrochemistry

Hamilton, JWJ, Byrne, JA, Dunlop, PSM, Dionysiou, DD, Pelaez, M, O’Shea, K, Synnott, D and Pillai, SC (2014) Evaluating the Mechanism of Visible Light Activity for N,F-TiO2Using Photoelectrochemistry. The Journal of Physical Chemistry C, 118 (23). p. 12206. [Journal article]

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URL: http://dx.doi.org/10.1021/jp4120964

DOI: doi:10.1021/jp4120964

Abstract

The improvement of the solar efficiency of photocatalytic materials is important for solar driven environmental remediation and solar energy harvesting applications. Photoelectrochemical characterization of nitrogen and fluorine codoped titanium dioxide (N,F-TiO2) was used to probe the mechanism of visible light activity. The spectral photocurrent response under visible irradiation did not correlate with the optical absorption spectrum of the N,F-TiO2; however, open-circuit photopotential measurements provided better correlation to the optical absorption spectra. These observations suggest that electrons excited to the conduction band from the N-induced midgap state are rapidly trapped by defect levels below the conduction band. Reactive oxygen species (ROS) can be produced via the reduction of molecular oxygen by conduction band electrons leading to the oxidative degradation of organic pollutants, and singlet oxygen may play a role. If there is no loss in the band gap activity, as compared to undoped titania, then any additional visible light activity may give an overall improvement in the solar efficiency. The photocurrent response should not be used as a direct measure of photocatalytic activity for doped titania as the oxygen reduction pathway is vitally important for the generation of ROS, whereas hole transfer from dopant midgap states may not be so critical.

Item Type:Journal article
Faculties and Schools:Faculty of Computing & Engineering
Faculty of Computing & Engineering > School of Engineering
Research Institutes and Groups:Engineering Research Institute
Engineering Research Institute > Nanotechnology & Integrated BioEngineering Centre (NIBEC)
ID Code:30130
Deposited By: Professor John Byrne
Deposited On:23 Oct 2014 12:28
Last Modified:23 Oct 2014 12:28

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