Synthesis of F-Doped Flower-like TiO<sub>2</sub> Nanostructures with High Photoelectrochemical Activity

Wu, Guosheng; Wang, Jingpeng; Thomas, Dan F.; Chen, Aicheng

doi:10.1021/la703098g

Cited by 286 publications

(194 citation statements)

References 24 publications

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“…Such dramatic compositional changes were due to rapid dissolution of titanium (Ti) substrate as shown in Equation (1). [37] Ti þ 6HF ! H 2 TiF 6 þ 2 H 2 " ð 1Þ…”

Section: Resultsmentioning

confidence: 99%

Facile Fabrication of Anatase TiO₂ Microspheres on Solid Substrates and Surface Crystal Facet Transformation from {001} to {101}

Zhang

Liu

et al. 2011

Chemistry A European J

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Anatase TiO(2) microspheres with controlled surface morphologies and exposed crystal facets were directly synthesized on metal titanium foil substrates by means of a facile, one-pot hydrothermal method without use of any templating reagent. The obtained products were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelecron spectroscopy (XPS), and the focused ion beam (FIB) technique. The sizes of the resultant microspheres ranged from 1.1 to 2.1 μm. The transformation of anatase TiO(2) microspheres with exposed {001} facets surface to nanosheets surface with {101} facets was achieved by simply controlling the hydrothermal reaction time. The anatase TiO(2) microspheres with exposed square-shaped plane {001} facets were obtained by controlling the reaction time at 1 h. The prolonged reaction time transforms the anatase TiO(2) microspheres with exposed square-shaped plane {001} facets to eroded {001} facets then to a nanosheet surface with exposed {101} facets. With hydrothermal synthesis, the surface morphological structure and crystal facets formation are highly dependent on dissolution/deposition processes, which can be strongly influenced by attributes, such as pH of the reaction media, the total concentration of dissolved and suspended titanium species, and the concentration of fluoride in the reaction solution. The changes of these attributes during the hydrothermal process were therefore measured and used to illustrate the morphology and crystal-facet transformation processes of anatase TiO(2) microspheres. The surface morphologies and crystal-facet transformations during hydrothermal processes were found to be governed by the compositional changes of the reaction media, driven by dynamically shifted dissolution/deposition equilibria. The photocatalytic activities of the photoanodes made of anatase TiO(2) microspheres were evaluated. The experimental results demonstrated that the photocatalytic activity of anatase TiO(2) microspheres with exposed {001} facets was found to be 1.5 times higher than that of the anatase TiO(2) microspheres with exposed {101} facets.

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“…Such dramatic compositional changes were due to rapid dissolution of titanium (Ti) substrate as shown in Equation (1). [37] Ti þ 6HF ! H 2 TiF 6 þ 2 H 2 " ð 1Þ…”

Section: Resultsmentioning

confidence: 99%

Facile Fabrication of Anatase TiO₂ Microspheres on Solid Substrates and Surface Crystal Facet Transformation from {001} to {101}

Zhang

Liu

et al. 2011

Chemistry A European J

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“…The presence of fluorides in the electrolyte causes the chemical dissolution of the titanium oxide to form the water-soluble [TiF 6 ] −2 complex. On the other hand, the complex also occurs with the Ti 4+ ions that are ejected at the interface of oxide-electrolyte by the following overall reactions [20][21][22][23][24][25][26].…”

Section: Resultsmentioning

confidence: 99%

Non-chapped, vertically well aligned titanium dioxide nanotubes fabricated by electrochemical etching

Nguyen¹,

Ung²,

Liem³

2014

Adv. Nat. Sci: Nanosci. Nanotechnol.

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This paper reports on the fabrication of non-chapped, vertically well aligned titanium dioxide nanotubes (TONTs) by using electrochemical etching method and further heat treatment. Very highly ordered metallic titanium nanotubes (TNTs) were formed by directly anodizing titanium foil at room temperature in an electrolyte composed of ammonium fluoride (NH 4 F), ethylene glycol (EG), and water. The morphology of as-formed TNTs is greatly dependent on the applied voltage, NH 4 F content and etching time. Particularly, we have found two interesting points related to the formation of TNTs: (i) the smooth surface without chaps of the largely etched area was dependent on the crystalline orientation of the titanium foil; and (ii) by increasing the anodizing potential from 15 V to 20 V, the internal diameter of TNT was increased from about 50 nm to 60 nm and the tube density decreased from 403 tubes μm −2 down to 339 tubes μm −2 , respectively. For the anodizing duration from 1 h to 5 h, the internal diameter of each TNT was increased from ∼30 nm to 60 nm and the tube density decreased from 496 tubes μm −2 down to 403 tubes μm −2 . After annealing at 400 °C in open air for 1 h, the TNTs were transformed into TONTs in anatase structure; further annealing at 600 °C showed the structural transformation from anatase to rutile as determined by Raman scattering spectroscopy.

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“…The XPS signal in the F 1s binding energy region consisted of only one band, peaking around 684 eV, due to surface fluoride ions. 30,38 No XPS signal at 688 eV, assigned to substitutional ions in the F-TiO 2 lattice, could ever be detected, possibly always being below the detection limit of the XPS technique. The effective dopant/Ti molar ratio determined by quantitative XPS analysis, also reported in Table 1, was usually lower than the nominal value according to the synthesis of the different doped TiO 2 series.…”

Section: Photocatalysts Structurementioning

confidence: 99%

“…Anion doping with p-block elements has been successfully pursued to sensitize TiO 2 towards visible light, 4,5 either by introducing newly created mid-gap energy states, or by narrowing the band gap itself. The effectiveness, but also the still not completely well understood nature of doping titanium dioxide with main group elements, such as N, 4,6-13 C, 5,14-17 B, [18][19][20] S, 13,15,[21][22][23][24][25] P, 26,27 I, 28,29 and F, [30][31][32][33][34][35][36][37][38][39] have been ascertained in a great number of studies, which also demonstrated that the insertion of dopant impurities in the oxide structure may increase the rate of undesired recombination of the photogenerated charge carriers. In contrast, the latter effect is known to become relatively lower, the higher is the crystallinity degree of the oxide structure.…”

Section: Introductionmentioning

confidence: 99%

Absorption and action spectra analysis of ammonium fluoride-doped titania photocatalysts

Dozzi

Ohtani

Selli

2011

Phys. Chem. Chem. Phys.

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The photocatalytic behaviour of a series of ammonium fluoride (NH 4 F) doped titania (TiO 2 ) photocatalysts has been investigated in the decomposition of acetic acid in aqueous suspension and in the gas phase mineralization of acetaldehyde. Very similar photoactivity trends, usually increasing with increasing the calcination temperature for a given nominal dopant amount, were obtained for the two test reactions. Moderately doped TiO 2 calcined at 700 °C, consisting of pure anatase, was the best performing photocatalyst in both reactions. In order to shed light on the origin of the enhanced photoactivity of such materials under visible light, acetic acid photooxidation was investigated systematically as a function of the irradiation wavelength, by collecting socalled action spectra. By comparing the shapes of the action spectra with those of the absorption spectra of the investigated photocatalysts a model is proposed, based on spectral features deconvolution, which allows a clear distinction between inactive light absorption, ascribed to nitrogen-doping, and effective photoactivity in acetic acid decomposition, possibly consequent to extrinsic absorption originated from surface oxygen vacancies or surface defects.2

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Synthesis of F-Doped Flower-like TiO₂ Nanostructures with High Photoelectrochemical Activity

Cited by 286 publications

References 24 publications

Facile Fabrication of Anatase TiO₂ Microspheres on Solid Substrates and Surface Crystal Facet Transformation from {001} to {101}

Facile Fabrication of Anatase TiO₂ Microspheres on Solid Substrates and Surface Crystal Facet Transformation from {001} to {101}

Non-chapped, vertically well aligned titanium dioxide nanotubes fabricated by electrochemical etching

Absorption and action spectra analysis of ammonium fluoride-doped titania photocatalysts

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Synthesis of F-Doped Flower-like TiO2 Nanostructures with High Photoelectrochemical Activity

Cited by 286 publications

References 24 publications

Facile Fabrication of Anatase TiO2 Microspheres on Solid Substrates and Surface Crystal Facet Transformation from {001} to {101}

Facile Fabrication of Anatase TiO2 Microspheres on Solid Substrates and Surface Crystal Facet Transformation from {001} to {101}

Non-chapped, vertically well aligned titanium dioxide nanotubes fabricated by electrochemical etching

Absorption and action spectra analysis of ammonium fluoride-doped titania photocatalysts

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Product

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Synthesis of F-Doped Flower-like TiO₂ Nanostructures with High Photoelectrochemical Activity

Facile Fabrication of Anatase TiO₂ Microspheres on Solid Substrates and Surface Crystal Facet Transformation from {001} to {101}

Facile Fabrication of Anatase TiO₂ Microspheres on Solid Substrates and Surface Crystal Facet Transformation from {001} to {101}