Highly selective photo-oxidation reactions at nanocrystalline TiO2 film electrodes

Wahl, Axel; Ulmann, M.; Carroy, A.; Augustyński, Jan

doi:10.1039/c39940002277

Cited by 48 publications

(28 citation statements)

References 7 publications

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“…A quantification of the oxalate effect on the photocurrent can be made based on the enhancement factor, F, defined as the ratio of the photocurrent in the presence of the organic divided by that in the supporting electrolyte alone. From Table 1, the above-mentioned trends can be readily identified and the significantly high value of F=5.09 for the P-TiO 2 (500°C) electrode is in line with similar data for other anatase-rich particulate electrodes reported [22,42]. It should be stressed that the fact that the photocurrent of thermal electrodes does not increase in the presence of organics does not necessarily mean that these are less efficient in organics degradation; if all the OH AE produced at thermal electrodes is consumed for the indirect oxidation of the organics then these electrodes could be equally effective with particulate electrodes of the same photocurrent levels.…”

Section: Experiments In the Presence Of Organicssupporting

confidence: 89%

“…Most particulate TiO 2 electrodes are either anatase or mixtures of anatase-rutile while there are only a few electrophotocatalytic studies of particulate laboratory-made rutile electrodes [4,7,22,23] and none of commercial Degussa P-25 transformed to rutile by high temperature annealing. At the same time, continuous TiO 2 film electrodes produced by simple thermal annealing have also not often been used in photooxidation applications [4,7,23].…”

Section: Introductionmentioning

confidence: 99%

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Photoelectrochemical characterisation of thermal and particulate titanium dioxide electrodes

et al. 2005

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The photoelectrocatalytic performance of thermal and particulate TiO 2 films on Ti electrode substrates has been studied by photovoltammetry and bulk photoelectrolysis. The thermal TiO 2 film electrodes were prepared by Ti annealing in air at 700°C and 500°C while the particulate electrodes were prepared from dispersions of Degussa P-25 TiO 2 deposited onto Ti substrates and subsequently sintered at 700°C and 500°C. The photocurrent in the absence and presence of the model organic species of oxalate as well as its photooxidation rate depends on coating surface area, type (thermal or particulate) and crystallographic form (anatase or rutile). A method is proposed to account for surface area variations by normalising the data with respect to the electroactive surface area of the TiO 2 electrodes, as estimated by their surface electrochemistry in the dark. The thermal electrodes show high photocurrents both in the absence and the presence of oxalate whereas the performance of particulate electrodes is significantly improved upon oxalate addition. Nevertheless, the efficiency of thermal 700°C TiO 2 for oxalate photooxidation during bulk photoelectrolysis is comparable to that of Degussa P-25 TiO 2 -coated electrodes.

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Section: Experiments In the Presence Of Organicssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Photoelectrochemical characterisation of thermal and particulate titanium dioxide electrodes

et al. 2005

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“…However, it should be emphasized that, in the context of nanomaterials, the above described formalism applies only to thin compact highly doped TiO 2 films that behave in a manner similar to compact crystalline semiconductors. In contrast, in small TiO 2 particles and in highly porous nanocrystalline electrodes, the formation of the space-charge layer is improbable due to the very small crystallite size [158][159][160][161][162][163]. In other words, the nearly depleted small TiO 2 crystals do not contain enough electrons in order to create an effective space-charge layer.…”

Section: Theory and Fundamental Conceptsmentioning

confidence: 94%

“…Here, the photocurrent is determined by the efficiency of photogenerated electron/hole transfer at the semiconductor/electrolyte and semiconductor/substrate interface [160][161][162][163]. This is schematically illustrated in Figure 7(b) which shows the mechanism of photocurrent generation at TiO 2 particles deposited on the conductive glass substrate (e.g., ITO).…”

Section: Photocurrent Onset Measurementsmentioning

confidence: 99%

(Photo)electrochemical Methods for the Determination of the Band Edge Positions of TiO₂‐Based Nanomaterials

Beránek

2011

Advances in Physical Chemistry

327

196

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TiO 2 -based nanomaterials play currently a major role in the development of novel photochemical systems and devices. One of the key parameters determining the photoactivity of TiO 2 -based materials is the position of the band edges. Although its knowledge is an important prerequisite for understanding and optimizing the performance of photochemical systems, it has been often rather neglected in recent research, particularly in the field of heterogeneous photocatalysis. This paper provides a concise account of main methods for the determination of the position of the band edges, particularly those suitable for measurements on nanostructured materials. In the first part, a survey of key photophysical and photochemical concepts necessary for understanding the energetics at the semiconductor/solution interface is provided. This is followed by a detailed discussion of several electrochemical, photoelectrochemical, and spectroelectrochemical methods that can be applied for the determination of band edge positions in compact and nanocrystalline thin films, as well as in nanocrystalline powders.

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“…Steady-state photocurrent-potential characteristics of WO 3 photoelectrodes Unlike nanoparticulate TiO 2 photoelectrodes, at which the photooxidation of water is almost suppressed [13], WO 3 photoelectrodes exhibit high activity both in acidic inorganic solutions and in the presence of various organic species. Figure 2(a) shows photocurrent-voltage curves for a WO 3 film electrode, irradiated with simulated solar AM 1.5 light, measured in 3 M H 2 SO 4(aq) solution and after addition of 0.1 mol L )1 of CH 3 OH.…”

Section: Resultsmentioning

confidence: 99%

Photoelectrolytic oxidation of organic species at mesoporous tungsten trioxide film electrodes under visible light illumination

et al. 2005

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Operation of a photoelectrolyser fitted with a semitransparent semiconducting WO 3 film photoanode is described. Due to its band-gap energy of 2.5 eV, the photoresponse of the WO 3 electrode extends into the blue part of the visible spectrum up to 500 nm. The WO 3 photoanode exhibits particularly high incident photon-to-current efficiencies for the oxidation of several organic species with the maximum occurring at ca. 400 nm. Experiments conducted under simulated AM 1.5 solar illumination demonstrated efficient photodegradation of a variety of organic chemicals including small organic molecules as well as EDTA and anthraquinonic Acid Blue 80 dye. Although, due to the inherent mass transport limitations, the described device appears best suited to the treatment of industrial wastewater containing from 100 ppm to few g L )1 of impurities, almost complete removal of organic carbon was observed in several photoelectrolysis runs. This is apparently associated with the concomitant photooxidation of sulphate-based supporting electrolyte resulting in the formation of a powerful chemical oxidant-persulphate.

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Highly selective photo-oxidation reactions at nanocrystalline TiO2 film electrodes

Cited by 48 publications

References 7 publications

Photoelectrochemical characterisation of thermal and particulate titanium dioxide electrodes

Photoelectrochemical characterisation of thermal and particulate titanium dioxide electrodes

(Photo)electrochemical Methods for the Determination of the Band Edge Positions of TiO₂‐Based Nanomaterials

Photoelectrolytic oxidation of organic species at mesoporous tungsten trioxide film electrodes under visible light illumination

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Highly selective photo-oxidation reactions at nanocrystalline TiO2 film electrodes

Cited by 48 publications

References 7 publications

Photoelectrochemical characterisation of thermal and particulate titanium dioxide electrodes

Photoelectrochemical characterisation of thermal and particulate titanium dioxide electrodes

(Photo)electrochemical Methods for the Determination of the Band Edge Positions of TiO2‐Based Nanomaterials

Photoelectrolytic oxidation of organic species at mesoporous tungsten trioxide film electrodes under visible light illumination

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(Photo)electrochemical Methods for the Determination of the Band Edge Positions of TiO₂‐Based Nanomaterials