Nanoporous‐Walled Tungsten Oxide Nanotubes as Highly Active Visible‐Light‐Driven Photocatalysts

Zhao, Zhigang; Miyauchi, Masahiro

doi:10.1002/anie.200802207

Cited by 398 publications

(223 citation statements)

References 23 publications

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“…have been reported to be used in water splitting to produce hydrogen or oxygen. [6][7][8][9][10][11][12] Among them, TiO 2 is the most extensively studied photocatalyst for its low toxicity, long-term thermodynamic stability, high photostability, and high efficiency. 5,12,13 Unfortunately, TiO 2 is only active in the ultraviolet light range due to its wide band gap (3.2 eV), result in utilizing only 5% of the total solar spectrum.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of WO₃@Graphene composite for enhanced photocatalytic oxygen evolution from water

et al. 2012

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Abstract"Nano tungsten oxide (WO3) particles were synthesized on the surface of graphene (GR) sheets by using a simple sonochemical method. The obtained composite, WO3@GR, was characterized by X-ray diffraction, N-2 adsorption/desorption analysis, thermo-gravimetric analysis, Raman spectroscopy and UV-vis diffuse reflectance spectra measurements. It was found that chemical bonds between the nano WO3 particles and the GR sheets were formed. The average particle size of the WO3 was evidenced to be around 12 nm on the GR sheets. When used as photocatalyst for water splitting, the amount of evolved O-2 from water for the WO3@GR composite with 40 wt% GR inside was twice and 1.8 times as much as that for pure WO3 and mixed-WO3/GR, respectively. The excellent photocatalytic property of the WO3@GR composite is due to the synergistic effects of the combined nano WO3 particles and GR sheets. The sensitization of WO3 by GR enhances the visible light absorption property of WO3@GR. The chemical bonding between WO3 and GR minimizes the interface defects, reducing the recombination of the photo-generated electron-hole pairs. Furthermore, the GR sheets in the WO3@GR composite enhance electrons transport by providing low resistance conduction pathways, leading to improved photo-conversion efficiency. The methodology opens up a new way of obtaining photoactive GR-semiconductor composites for photodissociating water under visible light." Nano tungsten oxide (WO 3 ) particles were synthesized on the surface of graphene (GR) sheets by using a simple sonochemical method. The obtained composite, WO 3 @GR, was characterized by X-ray diffraction, N 2 adsorption/desorption analysis, thermo-gravimetric analysis, Raman spectroscopy and UV-vis diffuse reflectance spectra measurements. It was found that chemical bonds between the nano WO 3 particles and the GR sheets were formed. The average particle size of the WO 3 was evidenced to be around 12 nm on the GR sheets. When used as photocatalyst for water splitting, the amount of evolved O 2 from water for the WO 3 @GR composite with 40 wt% GR inside was twice and 1.8 times as much as that for pure WO 3 and mixed-WO 3 /GR, respectively. The excellent photocatalytic property of the WO 3 @GR composite is due to the synergistic effects of the combined nano WO 3 particles and GR sheets. The sensitization of WO 3 by GR enhances the visible light absorption property of WO 3 @GR. The chemical bonding between WO 3 and GR minimizes the interface defects, reducing the recombination of the photo-generated electron-hole pairs. Furthermore, the GR sheets in the WO 3 @GR composite enhance electrons transport by providing low resistance conduction pathways, leading to improved photo-conversion efficiency. The methodology opens up a new way of obtaining photoactive GR-semiconductor composites for photodissociating water under visible light.

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Section: Introductionmentioning

confidence: 99%

Synthesis of WO₃@Graphene composite for enhanced photocatalytic oxygen evolution from water

et al. 2012

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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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“…However, the photocatalytic activity of pure WO 3 is not satisfactory because of its relatively low conduction-band level (0.5 V vs. NHE). To improve its photocatalytic performance, WO 3 was synthesized modified with Pt, [32,33] Cu, [34] and CuBi 2 O 4 . [35] These materials displayed significantly enhanced photocatalytic activity in terms of multielectron O 2 reduction.…”

Section: Introductionmentioning

confidence: 99%

Fe₃O₄/WO₃ Hierarchical Core–Shell Structure: High‐Performance and Recyclable Visible‐Light Photocatalysis

Yue

Cao

et al. 2011

Chemistry A European J

251

133

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A facile solvothermal epitaxial growth combined with a mild oxidation route has been developed for the fabrication of a magnetically recyclable Fe(3)O(4)/WO(3) core-shell visible-light photocatalyst. In this core-shell structured photocatalyst, visible-light-active WO(3) nanoplates (the shells) with high surface area are used as a medium to harvest absorbed photons and convert them to photogenerated charges, while conductive Fe(3)O(4) microspheres (the cores) are used as charge collectors to transport the photogenerated charges. This is a new role for magnetite. The Fe(3)O(4)/WO(3) core-shell structured photocatalysts possess large surface-exposure area, high visible-light-absorption efficiency, stable recyclability, and efficient charge-separation properties, the combination of which has rarely been reported in other visible-light-active photocatalysts. Photoelectrochemical investigations verify that the core-shell structured Fe(3)O(4)/WO(3) has a more effective photoconversion capability than pure WO(3) or Fe(3)O(4). At the same time, the visible-light photocatalytic ability of the Fe(3)O(4)/WO(3) photocatalyst has significantly enhanced activity in the photodegradation of organic-dye materials. The results presented herein provide new insights into core-shell materials as high-performance visible-light photocatalysts and their potential use in environmental protection.

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Nanoporous‐Walled Tungsten Oxide Nanotubes as Highly Active Visible‐Light‐Driven Photocatalysts

Cited by 398 publications

References 23 publications

Synthesis of WO₃@Graphene composite for enhanced photocatalytic oxygen evolution from water

Synthesis of WO₃@Graphene composite for enhanced photocatalytic oxygen evolution from water

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

Fe₃O₄/WO₃ Hierarchical Core–Shell Structure: High‐Performance and Recyclable Visible‐Light Photocatalysis

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Nanoporous‐Walled Tungsten Oxide Nanotubes as Highly Active Visible‐Light‐Driven Photocatalysts

Cited by 398 publications

References 23 publications

Synthesis of WO3@Graphene composite for enhanced photocatalytic oxygen evolution from water

Synthesis of WO3@Graphene composite for enhanced photocatalytic oxygen evolution from water

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

Fe3O4/WO3 Hierarchical Core–Shell Structure: High‐Performance and Recyclable Visible‐Light Photocatalysis

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Product

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About

Synthesis of WO₃@Graphene composite for enhanced photocatalytic oxygen evolution from water

Synthesis of WO₃@Graphene composite for enhanced photocatalytic oxygen evolution from water

Fe₃O₄/WO₃ Hierarchical Core–Shell Structure: High‐Performance and Recyclable Visible‐Light Photocatalysis