Cs-Modified WO<sub>3</sub> Photocatalyst Showing Efficient Solar Energy Conversion for O<sub>2</sub> Production and Fe (III) Ion Reduction under Visible Light

Miseki, Yugo; Kusama, Hitoshi; Sugihara, Hideki; Sayama, Kazuhiro

doi:10.1021/jz100233w

Cited by 123 publications

(87 citation statements)

References 21 publications

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“…Figure 6 shows XRD patterns of the film and the calcined powder of WO 3 ·H 2 O precipitates. Both patterns could be assigned to monoclinic WO 3 . The peak intensity of 002 diffraction for the film was found to be much higher than that for the particles.…”

Section: Resultsmentioning

confidence: 92%

Photoelectrochemical Property of Tungsten Oxide Films of Vertically Aligned Flakes for Visible-Light-Induced Water Oxidation

Amano¹,

Ding²,

Ohtani³

2011

J. Electrochem. Soc.

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A vertically arrayed flake film, "flake-wall film," of monoclinic tungsten oxide ͑WO 3 ͒ was prepared on a transparent conductive glass by controlling anisotropic crystal growth and self-arrayed growth of WO 3 hydrate with a layered crystal structure. The WO 3 flake-wall film exhibited superior performance for photoelectrochemical water oxidation under visible-light irradiation compared to that of a film consisting of horizontally laminated WO 3 flakes. The small differences between photocurrents under front-side irradiation and back-side irradiation and between photocurrents in the absence and the presence of methanol indicate the excellent electron transport property and long photogenerated carrier lifetime in the flake-wall film.

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Section: Resultsmentioning

confidence: 92%

Photoelectrochemical Property of Tungsten Oxide Films of Vertically Aligned Flakes for Visible-Light-Induced Water Oxidation

Amano¹,

Ding²,

Ohtani³

2011

J. Electrochem. Soc.

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“…A simple heat-treatment of tungstite (WO 3 .H 2 O) allows for the phase transformation to tungsten oxide (WO 3 ), an important class of n-type semiconductors with a tunable band gap of 2.5-2.8 eV [16]. Moreover, its high chemical stability, low production costs and non-toxicity have recently generated significant interests for a wide variety of applications in microelectronics and optoelectronics [17][18], super-hydrophilic thin films [15], dye-sensitized solar cells [19], colloidal quantum dot LEDs [20], photocatalysis [21] and photoelectrocatalysis [22], water splitting photocatalyst as main catalyst [23][24][25][26][27][28][29][30][31][32][33][34]. Environmental applications can also benefit from WO 3 as a visible light photocatalyst to generate OH radicals for bacteria destruction [35] and photocatalytic reduction of CO 2 into hydrocarbon fuels [36].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of tungstite (WO3·H2O) nanoleaves and nanoribbons

Ahmadi

Guinel

2014

Acta Materialia

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An environmentally benign method capable of producing large quantities of materials was used to synthesize tungstite (WO 3 .H 2 O) leaf-shaped nanoplatelets (LNPs) and nanoribbons (NRs). These materials were simply obtained by aging of colloidal solutions prepared by adding hydrochloric acid (HCl) to dilute sodium tungstate solutions (Na 2 WO 4 .2H 2 O) at a temperature of 5-10 o C. The aging medium and the pH of the precursor solutions were also investigated. Crystallization and growth occurred by Ostwald ripening during the aging of the colloidal solutions at ambient temperature for 24 to 48hrs. When dispersed in water, the LNPs and NRs take many days to settle, which is a clear advantage for some applications (e.g., photocatalysis). The materials were characterized using scanning and transmission electron microscopy, Raman and UV/Vis spectroscopies. The current versus voltage characteristics of the tungstite NRs showed that the material behaved as a Schottky diode with a breakdown electric field of 3.0x10 5 V.m -1 . They can also be heat treated at relatively low temperatures (300 o C) to form tungsten oxide (WO 3 ) NRs and be used as photoanodes for photoelectrochemical water splitting. Environmental applications can also benefit from WO 3 as a visible light photocatalyst to generate OH radicals for bacteria destruction [35] and photocatalytic reduction of CO 2 into hydrocarbon fuels [36]. The production of leaf-like WO 3 using a metallic tungsten surface exposed to a laser irradiation followed by an aging process has already been reported [37]. However, to the best of our knowledge, this is the first time that a very simple, inexpensive and environmentally benign synthesis of tungstite leaf-shaped nanoplatelets (LNPs) and nanoribbons (NRs) using colloidal chemistry is reported. Two steps are necessary to obtain these tungstite materials: The tungstate ions from sodium tungstate solutions (Na 2 WO 4 .2H 2 O) are first protonated and in a second step, dimerization and crystallization occur. The materials obtained were characterized using scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), UV/Vis, Raman and dynamic light scattering (DLS) spectroscopies. Moreover, the electrical properties of these materials were tested. Keywords

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“…Development of a photoelectrode material with visible light response has been sought for efficient utilization of solar energy. It has been reported that Fe 2 O 3 (9-11), WO 3 (12)(13)(14), BiVO 4 (15)(16)(17)(18)(19)(20)(21)(22)(23)(24), and SrTiO 3 ∶Rh (25) of metal oxide electrodes respond to visible light. Recently, some (oxy) nitride materials such as TaON (26,27), Ta 3 N 5 (27,28), SrNbO 2 N (29), and Ta 0.9 Co 0.1 N x (30) have also been found to be visible light responsive photoelectrodes for water splitting.…”

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confidence: 99%

Facile fabrication of an efficient BiVO ₄ thin film electrode for water splitting under visible light irradiation

Jia

Iwashina²,

Kudo³

2012

Proc. Natl. Acad. Sci. U.S.A.

292

186

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An efficient BiVO 4 thin film electrode for overall water splitting was prepared by dipping an F-doped SnO 2 (FTO) substrate electrode in an aqueous nitric acid solution of BiðNO 3 Þ 3 and NH 4 VO 3 , and subsequently calcining it. X-ray diffraction of the BiVO 4 thin film revealed that a photocatalytically active phase of scheelite-monoclinic BiVO 4 was obtained. Scanning electron microscopy images showed that the surface of an FTO substrate was uniformly coated with the BiVO 4 film with 300-400 nm of the thickness. The BiVO 4 thin film electrode gave an excellent anodic photocurrent with 73% of an IPCE at 420 nm at 1.0 V vs. Ag∕AgCl. Modification with CoO on the BiVO 4 electrode improved the photoelectrochemical property. A photoelectrochemical cell consisting of the BiVO 4 thin film electrode with and without CoO, and a Pt counter electrode was constructed for water splitting under visible light irradiation and simulated sunlight irradiation. Photocurrent due to water splitting to form H 2 and O 2 was confirmed with applying an external bias smaller than 1.23 V that is a theoretical voltage for electrolysis of water. Water splitting without applying external bias under visible light irradiation was demonstrated using a SrTiO 3 ∶Rh photocathode and the BiVO 4 photoanode.hydrogen production | solar energy conversion | visible light response T he development of powdered photocatalysts and semiconductor photoelectrodes for water splitting have been studied extensively in view of utilization of solar energy, since the report of the Honda-Fujishima effect (1). There are advantageous and disadvantageous points for water splitting using the powdered photocatalysts and photoelectrochemical cells. Although a powdered photocatalyst system is simple, H 2 and O 2 are produced as a mixture. In contrast to it, photoelectrochemical cells give H 2 separately from O 2 gas. Moreover, even if powdered photocatalysts do not possess band potentials suitable for water splitting (the bottom of the conduction band <0 V and the top of the valence band >1.23 V vs. NHE at pH 0), water splitting may be achieved by application of these powdered photocatalysts to photoelectrodes with applying some external bias. However, the electrical conductivity of semiconductor electrode is indispensable, resulting in that the number of the photoelectrode materials is limited.It has been reported that many metal oxides are active photocatalysts for water splitting into H 2 and O 2 stoichiometrically under UV light irradiation (2). Photoelectrodes, such as TiO 2 (1, 3, 4), SrTiO 3 (5, 6), BaTiO 3 (7), and KTaO 3 (8) have been reported for photoelectrochemical water splitting under UV light irradiation. Development of a photoelectrode material with visible light response has been sought for efficient utilization of solar energy. It has been reported that Fe 2 O 3 (9-11), WO 3 (12-14), BiVO 4 (15-24), and SrTiO 3 ∶Rh (25) of metal oxide electrodes respond to visible light. Recently, some (oxy) nitride materials such as TaON (26,27), Ta 3 N 5 (27, 28), SrN...

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Cs-Modified WO₃ Photocatalyst Showing Efficient Solar Energy Conversion for O₂ Production and Fe (III) Ion Reduction under Visible Light

Cited by 123 publications

References 21 publications

Photoelectrochemical Property of Tungsten Oxide Films of Vertically Aligned Flakes for Visible-Light-Induced Water Oxidation

Photoelectrochemical Property of Tungsten Oxide Films of Vertically Aligned Flakes for Visible-Light-Induced Water Oxidation

Synthesis and characterization of tungstite (WO3·H2O) nanoleaves and nanoribbons

Facile fabrication of an efficient BiVO ₄ thin film electrode for water splitting under visible light irradiation

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Cs-Modified WO3 Photocatalyst Showing Efficient Solar Energy Conversion for O2 Production and Fe (III) Ion Reduction under Visible Light

Cited by 123 publications

References 21 publications

Photoelectrochemical Property of Tungsten Oxide Films of Vertically Aligned Flakes for Visible-Light-Induced Water Oxidation

Photoelectrochemical Property of Tungsten Oxide Films of Vertically Aligned Flakes for Visible-Light-Induced Water Oxidation

Synthesis and characterization of tungstite (WO3·H2O) nanoleaves and nanoribbons

Facile fabrication of an efficient BiVO 4 thin film electrode for water splitting under visible light irradiation

Contact Info

Product

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Cs-Modified WO₃ Photocatalyst Showing Efficient Solar Energy Conversion for O₂ Production and Fe (III) Ion Reduction under Visible Light

Facile fabrication of an efficient BiVO ₄ thin film electrode for water splitting under visible light irradiation