Tungsten trioxide as an electrode for photoelectrolysis of water

Butler, M. A.; Nasby, R.D.; Quinn, Rod K.

doi:10.1016/0038-1098(76)90642-6

Cited by 200 publications

(100 citation statements)

References 13 publications

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“…[1] The photoelectrochemical behavior of tungsten trioxide was studied in the late 1970s and early 1980s in the case of both polycrystalline [2][3][4][5][6][7][8][9] and monocrystalline samples. [10,11] This research was mainly devoted to the semiconducting characteristics of the oxide and to the photooxidation of water. The photooxidation of halide anions was also reported [9] and studied in connection with the competitive photooxidation of water.…”

Section: Introductionmentioning

confidence: 99%

Photoelectrochemical Behavior of Nanostructured WO₃ Thin‐Film Electrodes: The Oxidation of Formic Acid

et al. 2006

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Nanostructured tungsten trioxide thin-film electrodes are prepared on conducting glass substrates by either potentiostatic electrodeposition from aqueous solutions of peroxotungstic acid or direct deposition of WO3 slurries. Once treated thermally in air at 450 degrees C, the electrodes are found to be composed of monoclinic WO3 grains with a particle size around 30-40 nm. The photoelectrochemical behavior of these electrodes in 1 M HClO4 apparently reveals a low degree of electron-hole recombination. Upon addition of formic acid, the electrode showed the current multiplication phenomenon together with a shift of the photocurrent onset potential toward less positive values. Photoelectrochemical experiments devised on the basis of a kinetic model reported recently [I. Mora-Seró, T. Lana-Villarreal, J. Bisquert, A. Pitarch, R. Gómez, P. Salvador, J. Phys. Chem. B 2005, 109, 3371] showed that an interfacial mechanism of inelastic, direct hole transfer takes place in the photooxidation of formic acid. This behavior is attributed to the tendency of formic acid molecules to be specifically adsorbed on the WO3 nanoparticles, as evidenced by attenuated total reflection infrared spectroscopy.

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Section: Introductionmentioning

confidence: 99%

Photoelectrochemical Behavior of Nanostructured WO₃ Thin‐Film Electrodes: The Oxidation of Formic Acid

et al. 2006

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“…One disadvantage of employing TiO 2 as a photocatalyst is its large band gap energy of 3.0 eV (rutile) which corresponds to an absorption of light with wavelengths ≤413 nm resulting in the utilization of only a very small part of the incoming sunlight (4%-5%). Since the early works by Hodes et al 15 and separately by Butler et al 16,17 tungsten trioxide has been considered as an alternative and promising photoanode material. The smaller optical band gap of tungsten oxide (2.6 eV) allows a more efficient harvesting of the total solar light irradiation due to some visible light absorption.…”

Section: Introductionmentioning

confidence: 99%

Cold sprayed WO₃and TiO₂electrodes for photoelectrochemical water and methanol oxidation in renewable energy applications

et al. 2017

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Films prepared by cold spray have potential applications as photoanodes in electrochemical water splitting and waste water purification. In the present study cold sprayed photoelectrodes produced with WO 3 (active under visible light illumination) and TiO 2 (active under UV illumination) on titanium metal substrates were investigated as photoanodes for the oxidation of water and methanol, respectively. Methanol was chosen as organic model pollutant in acidic electrolytes. Main advantages of the cold sprayed photoelectrodes are the improved metal-semiconductor junctions and the superior mechanical stability.Additionally, the cold spray method can be utilized as a large-scale electrode fabrication technique for photoelectrochemical applications. Incident photon to current efficiencies reveal that cold sprayed TiO 2 / WO 3 photoanodes exhibit the best photoelectrochemical properties with regard to the water and methanol oxidation reactions in comparison with the benchmark photocatalyst Aeroxide TiO 2 P25 due to more efficient harvesting of the total solar light irradiation related to their smaller band gap energies.

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“…WO 3 electrodes that have been "aged" by extended photoelectrolysis in 1 M H 2 SO 4 give a linear region in a Tauc plot, that is, (Z ph hn) 1/2 versus hn (where Z ph is the IPCE close to the band edge and hn is the energy of the incident light), which is indicative of an indirect interband transition. The intercept of the hn axis affords the bandgap energy, about 2.5 eV in this case [12], slightly lower than that found for single-crystalline WO 3 [11]. The large enhancement of the photocurrent efficiency for the thermally grown WO 3 electrode was assigned to a partial extraction of ionic defects (interstitial W 5 þ and W 6 þ ) from the film, which migrate towards the oxide/electrolyte interface due to the effect of the applied anodic bias [12].…”

Section: Macrocrystalline Wo 3 Filmsmentioning

confidence: 96%

“…This resulted in photoelectrolysis of water assisted by an external bias, with hydrogen generated at the cathode and oxygen formed at the photoanode. The bandgap energies, derived from photocurrent measurements, were strongly affected by the preparation procedure and ranged from 2.7 eV for single-crystalline WO 3 [11] to values corresponding to even the near-UV range for films that were apparently only slightly substoichiometric. The close relationship between the film stoichiometry and the extent of the visible-light photoresponse was clearly demonstrated by Gissler and Memming [10] for the case of tungsten oxide films thermally grown on the W metal.…”

Section: Macrocrystalline Wo 3 Filmsmentioning

confidence: 99%

“…Given the low absorption coefficients, a, in WO 3 for photons with energies close to the bandgap, the optical penetration depth, 1/a, for light of visible wavelengths may be of the order of several micrometers [6,13]. In addition to this, the hole diffusion length, L p , in materials with an indirect optical transition, is quite low, about 0.15 mm in WO 3 [11]: an efficient separation of the electron-hole pairs would require the establishment of a potentially wide space-charge layer in order to match 1/a. A simple estimate shows that even for the case of a semiconductor with moderate doping levels, that is, N D ¼ 10 16 cm À3 , and a band bending as large as 1 V, the width of the space-charge layer in WO 3 does not exceed 0.8 mm [13].…”

Section: Limitations Of Macroscopic Womentioning

confidence: 99%

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Nanostructured Thin-Film WO3 Photoanodes for Solar Water and Sea-Water Splitting

Alexander

Augustyński

On Solar Hydrogen &Amp; Nanotechnology

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Tungsten trioxide, WO 3 , is a versatile material with numerous diverse applications that range from catalysis [1], to electrocatalysis [2], through gas sensors [3] and (photo)electrochromic devices [4], to photoelectrochemical water splitting [5]. In the majority of these cases, WO 3 is employed in thin films and the choice of whether it is in the amorphous or crystalline form is essential. The first extensive study of the optical and electrochromic properties of WO 3 films, by Deb [6], was motivated by the observation of the formation of color centers in WO 3 , either under irradiation by UV light (photochromism) or by the application of an electric field (electrochromism). Measurement of the absorption spectra revealed a large difference between optical absorption edges of amorphous and crystalline WO 3 (about 0.38 eV); the absorption edge moves to lower energy upon crystallization, corresponding to a bandgap of 3.25 eV. In fact, the latter value is still significantly larger than the bandgap energy of 2.5 eV subsequently derived from photocurrent measurements for crystalline, and indeed nanocrystalline, WO 3 films. This difference is most likely due to the presence of some substoichiometric W 18 O 49 in the crystalline material prepared by Deb, and the apparently smaller bandgap in nanocrystalline films which will be discussed later in this chapter. Irradiating WO 3 films with photons that have energies within the bandgap was observed to form blue color centers. This coloration occurs more efficiently in disordered amorphous films and in the presence of moisture. In what

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Tungsten trioxide as an electrode for photoelectrolysis of water

Cited by 200 publications

References 13 publications

Photoelectrochemical Behavior of Nanostructured WO₃ Thin‐Film Electrodes: The Oxidation of Formic Acid

Photoelectrochemical Behavior of Nanostructured WO₃ Thin‐Film Electrodes: The Oxidation of Formic Acid

Cold sprayed WO₃and TiO₂electrodes for photoelectrochemical water and methanol oxidation in renewable energy applications

Nanostructured Thin-Film WO3 Photoanodes for Solar Water and Sea-Water Splitting

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Tungsten trioxide as an electrode for photoelectrolysis of water

Cited by 200 publications

References 13 publications

Photoelectrochemical Behavior of Nanostructured WO3 Thin‐Film Electrodes: The Oxidation of Formic Acid

Photoelectrochemical Behavior of Nanostructured WO3 Thin‐Film Electrodes: The Oxidation of Formic Acid

Cold sprayed WO3and TiO2electrodes for photoelectrochemical water and methanol oxidation in renewable energy applications

Nanostructured Thin-Film WO3 Photoanodes for Solar Water and Sea-Water Splitting

Contact Info

Product

Resources

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Photoelectrochemical Behavior of Nanostructured WO₃ Thin‐Film Electrodes: The Oxidation of Formic Acid

Photoelectrochemical Behavior of Nanostructured WO₃ Thin‐Film Electrodes: The Oxidation of Formic Acid

Cold sprayed WO₃and TiO₂electrodes for photoelectrochemical water and methanol oxidation in renewable energy applications