Chemistry in a confined space: Characterization of nitrogen-doped titanium oxide nanotubes produced by calcining ammonium trititanate nanotubes

Jui Chun Chang, Wei Je Tsai, Tsai Chin Chiu, Chih Wei Liu, Jiunn Hsing Chao, Chiu-Hsun Lin

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

Ammonium trititanate nanotubes ((NH4)2Ti 3O7, abbreviated as NH4TNT) were produced from sodium trititanate nanotubes (Na2Ti3O7, abbreviated as NaTNT) by ion exchange using 1.0 M NH4NO3. Substituting NH4+ for Na+ reduced the band gap energy (Eg) of the trititanate nanotubes. Calcining NH4TNT at 473 K reduced the inter-layer spacing in the nanotube wall, and further reduced the value of Eg, yielding NH4TNT that responded to visible light. As NH4+ cations were intercalated in the small inter-layer space of NH4TNT, calcination at 573 K decomposed NH4+ (NH4TNT → NH3 + HTNT) and produced inside the nanotube wall NH3 gas at a high pressure, which fractured and thereby shortened the nanotubes. Calcination at 573 K also caused a phase transformation from hydrogen trititanate to TiO2. Calcination at 673 K induced the dehydrogenation of NH3 molecules that were confined to the nanotube wall, producing interstitial NH2 species. Calcinations at between 573 and 673 K resulted in the formation of N-TiO 2 (B) nanotubes and N-anatase nanotubes, which have a narrow band gap (2.96 ∼ 2.76 eV) and respond to visible light. Further calcination at ≥ 773 K caused the loss of N species and the disappearance of the tubular pore of the nanotubes. The activities of N-doped TiO2 nanomaterials that were calcined at various temperatures in degrading methylene blue followed the order: 673 > 573 > 473 >773 > 873 K. The active N species in these N-doped TiO2 are molecular nitrogen species, including NH 4+ and NH3 at high concentrations (3.8 ∼ 1.2 atomic %) at 473 and 573 K, and NH2 at a low concentration (0.4 ∼ 0.2 atomic %) at 673 and 773 K. The nature and concentration of the N species, surface area, the crystallinity and the crystalline composition of the material govern the photocatalytic activity of N-doped TiO2 that is prepared by calcining the NH4TNT.

Original languageEnglish
Pages (from-to)4605-4614
Number of pages10
JournalJournal of Materials Chemistry
Volume21
Issue number12
DOIs
Publication statusPublished - 2011 Mar 28

Fingerprint

Titanium oxides
Ammonium Compounds
Nanotubes
Nitrogen
Calcination
Energy gap
titanium dioxide
Methylene Blue
Dehydrogenation
Nanostructured materials
Titanium dioxide
Cations
Hydrogen
Ion exchange
Gases
Phase transitions
Positive ions
Sodium
Crystalline materials
Molecules

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Chemistry

Cite this

Chang, Jui Chun ; Tsai, Wei Je ; Chiu, Tsai Chin ; Liu, Chih Wei ; Chao, Jiunn Hsing ; Lin, Chiu-Hsun. / Chemistry in a confined space : Characterization of nitrogen-doped titanium oxide nanotubes produced by calcining ammonium trititanate nanotubes. In: Journal of Materials Chemistry. 2011 ; Vol. 21, No. 12. pp. 4605-4614.
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abstract = "Ammonium trititanate nanotubes ((NH4)2Ti 3O7, abbreviated as NH4TNT) were produced from sodium trititanate nanotubes (Na2Ti3O7, abbreviated as NaTNT) by ion exchange using 1.0 M NH4NO3. Substituting NH4+ for Na+ reduced the band gap energy (Eg) of the trititanate nanotubes. Calcining NH4TNT at 473 K reduced the inter-layer spacing in the nanotube wall, and further reduced the value of Eg, yielding NH4TNT that responded to visible light. As NH4+ cations were intercalated in the small inter-layer space of NH4TNT, calcination at 573 K decomposed NH4+ (NH4TNT → NH3 + HTNT) and produced inside the nanotube wall NH3 gas at a high pressure, which fractured and thereby shortened the nanotubes. Calcination at 573 K also caused a phase transformation from hydrogen trititanate to TiO2. Calcination at 673 K induced the dehydrogenation of NH3 molecules that were confined to the nanotube wall, producing interstitial NH2 species. Calcinations at between 573 and 673 K resulted in the formation of N-TiO 2 (B) nanotubes and N-anatase nanotubes, which have a narrow band gap (2.96 ∼ 2.76 eV) and respond to visible light. Further calcination at ≥ 773 K caused the loss of N species and the disappearance of the tubular pore of the nanotubes. The activities of N-doped TiO2 nanomaterials that were calcined at various temperatures in degrading methylene blue followed the order: 673 > 573 > 473 >773 > 873 K. The active N species in these N-doped TiO2 are molecular nitrogen species, including NH 4+ and NH3 at high concentrations (3.8 ∼ 1.2 atomic {\%}) at 473 and 573 K, and NH2 at a low concentration (0.4 ∼ 0.2 atomic {\%}) at 673 and 773 K. The nature and concentration of the N species, surface area, the crystallinity and the crystalline composition of the material govern the photocatalytic activity of N-doped TiO2 that is prepared by calcining the NH4TNT.",
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Chemistry in a confined space : Characterization of nitrogen-doped titanium oxide nanotubes produced by calcining ammonium trititanate nanotubes. / Chang, Jui Chun; Tsai, Wei Je; Chiu, Tsai Chin; Liu, Chih Wei; Chao, Jiunn Hsing; Lin, Chiu-Hsun.

In: Journal of Materials Chemistry, Vol. 21, No. 12, 28.03.2011, p. 4605-4614.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Chemistry in a confined space

T2 - Characterization of nitrogen-doped titanium oxide nanotubes produced by calcining ammonium trititanate nanotubes

AU - Chang, Jui Chun

AU - Tsai, Wei Je

AU - Chiu, Tsai Chin

AU - Liu, Chih Wei

AU - Chao, Jiunn Hsing

AU - Lin, Chiu-Hsun

PY - 2011/3/28

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N2 - Ammonium trititanate nanotubes ((NH4)2Ti 3O7, abbreviated as NH4TNT) were produced from sodium trititanate nanotubes (Na2Ti3O7, abbreviated as NaTNT) by ion exchange using 1.0 M NH4NO3. Substituting NH4+ for Na+ reduced the band gap energy (Eg) of the trititanate nanotubes. Calcining NH4TNT at 473 K reduced the inter-layer spacing in the nanotube wall, and further reduced the value of Eg, yielding NH4TNT that responded to visible light. As NH4+ cations were intercalated in the small inter-layer space of NH4TNT, calcination at 573 K decomposed NH4+ (NH4TNT → NH3 + HTNT) and produced inside the nanotube wall NH3 gas at a high pressure, which fractured and thereby shortened the nanotubes. Calcination at 573 K also caused a phase transformation from hydrogen trititanate to TiO2. Calcination at 673 K induced the dehydrogenation of NH3 molecules that were confined to the nanotube wall, producing interstitial NH2 species. Calcinations at between 573 and 673 K resulted in the formation of N-TiO 2 (B) nanotubes and N-anatase nanotubes, which have a narrow band gap (2.96 ∼ 2.76 eV) and respond to visible light. Further calcination at ≥ 773 K caused the loss of N species and the disappearance of the tubular pore of the nanotubes. The activities of N-doped TiO2 nanomaterials that were calcined at various temperatures in degrading methylene blue followed the order: 673 > 573 > 473 >773 > 873 K. The active N species in these N-doped TiO2 are molecular nitrogen species, including NH 4+ and NH3 at high concentrations (3.8 ∼ 1.2 atomic %) at 473 and 573 K, and NH2 at a low concentration (0.4 ∼ 0.2 atomic %) at 673 and 773 K. The nature and concentration of the N species, surface area, the crystallinity and the crystalline composition of the material govern the photocatalytic activity of N-doped TiO2 that is prepared by calcining the NH4TNT.

AB - Ammonium trititanate nanotubes ((NH4)2Ti 3O7, abbreviated as NH4TNT) were produced from sodium trititanate nanotubes (Na2Ti3O7, abbreviated as NaTNT) by ion exchange using 1.0 M NH4NO3. Substituting NH4+ for Na+ reduced the band gap energy (Eg) of the trititanate nanotubes. Calcining NH4TNT at 473 K reduced the inter-layer spacing in the nanotube wall, and further reduced the value of Eg, yielding NH4TNT that responded to visible light. As NH4+ cations were intercalated in the small inter-layer space of NH4TNT, calcination at 573 K decomposed NH4+ (NH4TNT → NH3 + HTNT) and produced inside the nanotube wall NH3 gas at a high pressure, which fractured and thereby shortened the nanotubes. Calcination at 573 K also caused a phase transformation from hydrogen trititanate to TiO2. Calcination at 673 K induced the dehydrogenation of NH3 molecules that were confined to the nanotube wall, producing interstitial NH2 species. Calcinations at between 573 and 673 K resulted in the formation of N-TiO 2 (B) nanotubes and N-anatase nanotubes, which have a narrow band gap (2.96 ∼ 2.76 eV) and respond to visible light. Further calcination at ≥ 773 K caused the loss of N species and the disappearance of the tubular pore of the nanotubes. The activities of N-doped TiO2 nanomaterials that were calcined at various temperatures in degrading methylene blue followed the order: 673 > 573 > 473 >773 > 873 K. The active N species in these N-doped TiO2 are molecular nitrogen species, including NH 4+ and NH3 at high concentrations (3.8 ∼ 1.2 atomic %) at 473 and 573 K, and NH2 at a low concentration (0.4 ∼ 0.2 atomic %) at 673 and 773 K. The nature and concentration of the N species, surface area, the crystallinity and the crystalline composition of the material govern the photocatalytic activity of N-doped TiO2 that is prepared by calcining the NH4TNT.

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