Ladungstrennung in nanoskaligen Titanat‐Schichten: Einfluss von Ionenaustausch und Morphologieumwandlung auf die photoelektronischen Eigenschaften

Riss, Alexander; Berger, Thomas; Stankic, Slavica; Bernardi, Johannes; Knözinger, Erich; Diwald, Oliver

doi:10.1002/ange.200703817

Cited by 4 publications

(12 citation statements)

References 53 publications

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“…Raman spectra of the samples before and after the ion exchange are shown in Figure . For Na‐TNFs in Figure 3a, the spectra are essentially the same as the data reported for layered tri‐titanates 33, 42–44. And for Na‐TNSs in Figure 3b, the spectra are the same as the report for tri‐titanates synthesized at relatively lower temperature or lower NaOH concentration 45–48.…”

Section: Resultssupporting

confidence: 73%

“…In addition, the titanates are readily fabricated by a hydrothermal treatment of Ti precursors in concentrated NaOH solutions at moderate temperature. Various Ti precursors (rutile, anatase, and amorphous TiO 2 ) can be used to synthesize the titanates with close to 100% conversion efficiency 29–33. Herein, industrial grade metatitanic acid (TiO 2 •H 2 O) is chosen as the Ti precursor which makes the synthesis very cost effective for industrial‐scale applications.…”

Section: Introductionmentioning

confidence: 99%

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Highly Efficient, Irreversible and Selective Ion Exchange Property of Layered Titanate Nanostructures

Li¹,

Zhang²,

Chen³

et al. 2011

Adv Funct Materials

235

133

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Layered titanates (Na2Ti3O7·nH2O) with exchangeable sodium cations located in the interlayer have been synthesized by simple hydrothermal treatment of Ti precursor in concentrated NaOH solutions. By proper control of the synthesis conditions, different morphologies of nanofibers and nanosheets are obtained. The metastable layered structure of the titanates collapses during the ion exchange, resulting in irreversible ion exchange. Target cations (eg., Ag+, Cu2+, Pb2+ and Eu3+) are completely concentrated from water and then tightly immobilized in the interlayer which is of great significance for the removal and subsequent safe disposal of hazardous metal cations. The ion exchange of the nanosheets is much more efficient than that of the nanofibers and other inorganic ion exchangers due to the larger surface area, less stable layered structure and larger amount of interlayer water of the nanosheets. The ion exchange of the titanates is also very selective. Valence, hardness, and radius of cations are main factors affecting the selectivity. Cations trapped in the interlayer are released by an acid‐induced phase transformation of the titanate nanosheets to rutile. Then the rutile can be used as a new Ti precursor to synthesize the titanate nanostructures, resulting in a full cycle of material use. The nanosheets may find applications in the decontamination and safe disposal of radioactive and heavy metal cations and also in the collection of valuable cations from water.

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Section: Resultssupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Highly Efficient, Irreversible and Selective Ion Exchange Property of Layered Titanate Nanostructures

Li¹,

Zhang²,

Chen³

et al. 2011

Adv Funct Materials

235

133

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“…The XRD pattern of Na 2 Ti 3 O 7 nanowires shows broad reflections, the width of which results from a limited coherence volume of these structures. [21] The most prominent feature at 2q = 10.98 corresponds to the interlayer spacing of the titanate nanosheets (Figure 4 a). [25] NaTaO 3 cubes crystallize in the perovskite structure.…”

Section: Sample Namementioning

confidence: 99%

“…This effect is attributed to titanate nanosheets, which emerge as a result of unscrolling of nanoscrolls as reaction intermediates and which form stacks of plane sheets comprising the Na 2 Ti 3 O 7 nanowires. [21] In the course of Ta 2 O 5 dissolution and the simultaneous crystallization and growth of NaTaO 3 cubes ( Figure 11 c) these sheets are expected to keep nucleation events separated and to favor shielded growth of NaTaO 3 . Thus, the pH-induced transformation of layered titanate nanostructures [7,20,21] makes titanate nanosheets promising precursor structures, which provide control over the distribution of different metal oxide nanostructures and associated interfaces.…”

Section: Sample Namementioning

confidence: 99%

On the Entangled Growth of NaTaO₃ Cubes and Na₂Ti₃O₇ Wires in Sodium Hydroxide Solution

Baumann¹,

Liu

Elser

et al. 2013

Chemistry A European J

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The entangled growth of sodium titanate Na2Ti3O7 nanowires and sodium tantalate NaTaO3 cubes was investigated with electron microscopy, X-ray diffraction, and UV diffuse reflectance spectroscopy. Depending on the composition of the Ta2O5- and TiO2-particle-based powder mixtures, which served as educts, we observed different types of hybridization effects. These include the titanium-induced contraction of the NaTaO3 perovskite-type unit cell and the generation of electronic defect states in NaTaO3 that give rise to optical subbandgap transitions and tantalum-induced limitations of the Na2Ti3O7 nanowire growth. The transformation from Ta2O5 to NaTaO3 occurs through a dissolution-recrystallization process. A systematic analysis of the impact of different titanium sources on NaTaO3 dispersion and, thus, on the properties of the entangled nanostructures revealed that a perfect intermixture of cubes and nanowires can only be achieved when titanate nanosheets emerge during transformation as reaction intermediates and shield nucleation and growth of isolated NaTaO3 cubes. The here demonstrated approach can be highly instrumental for understanding the nucleation and growth of composite and entangled nanostructures in solution and--at the same time--provides an interesting new class of photoactive composite materials.

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“…The data corresponded to identical weights of sample material. [17] MB was physically adsorbed onto the surface of TiNT through electrostatic interactions. [6] MB could not be removed by washing, and, although they exhibited a high adsorption capacity, the unmodified nanotubes had no appreciable photocatalytic activity; the dye could not be degraded by prolonged illumination.…”

Section: Resultsmentioning

confidence: 99%

Dopamine‐Modified Trititanate Nanotubes with UV‐ and Visible‐Light Photocatalytic Activity: Coordinative Self‐Assembly into a Recyclable Absorber

Dawson

Liu

et al. 2012

ChemCatChem

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The search for a simple method to bestow trititanate nanotubes with visible‐light activity for applications as solar‐driven photocatalysts remains a challenging task. Here, we report that self‐assembled surface modification by dopamine imparted trititanate nanotubes (TiNT) with stable, recyclable photocatalytic activity under UV and visible‐light illumination. The controlled surface modification shifted the absorption onset into the visible region. These dopamine‐modified trititanate nanotubes are expected to have applications in water treatment and in pollutant degradation.

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Ladungstrennung in nanoskaligen Titanat‐Schichten: Einfluss von Ionenaustausch und Morphologieumwandlung auf die photoelektronischen Eigenschaften

Cited by 4 publications

References 53 publications

Highly Efficient, Irreversible and Selective Ion Exchange Property of Layered Titanate Nanostructures

Highly Efficient, Irreversible and Selective Ion Exchange Property of Layered Titanate Nanostructures

On the Entangled Growth of NaTaO₃ Cubes and Na₂Ti₃O₇ Wires in Sodium Hydroxide Solution

Dopamine‐Modified Trititanate Nanotubes with UV‐ and Visible‐Light Photocatalytic Activity: Coordinative Self‐Assembly into a Recyclable Absorber

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Ladungstrennung in nanoskaligen Titanat‐Schichten: Einfluss von Ionenaustausch und Morphologieumwandlung auf die photoelektronischen Eigenschaften

Cited by 4 publications

References 53 publications

Highly Efficient, Irreversible and Selective Ion Exchange Property of Layered Titanate Nanostructures

Highly Efficient, Irreversible and Selective Ion Exchange Property of Layered Titanate Nanostructures

On the Entangled Growth of NaTaO3 Cubes and Na2Ti3O7 Wires in Sodium Hydroxide Solution

Dopamine‐Modified Trititanate Nanotubes with UV‐ and Visible‐Light Photocatalytic Activity: Coordinative Self‐Assembly into a Recyclable Absorber

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Product

Resources

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On the Entangled Growth of NaTaO₃ Cubes and Na₂Ti₃O₇ Wires in Sodium Hydroxide Solution