Nitrogen doped TiO2 photocatalyst prepared by low energy N+ implantation technique

Yoshida, Tomoko; Kuda, Eriko

doi:10.1016/s0167-2991(10)75039-4

Cited by 5 publications

(3 citation statements)

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“…In the N 1s spectra, TON had a single peak at 396 eV, while O X TON-673 K (2%) had double peaks at 396 and 402 eV. The double peaks are assigned to N bonded to Ti (N Ti ) and O–N–O (NO x ) species (N NO ). , The intensity of N Ti significantly decreased after the oxidation, showing a decrease in the N content. The O 1s XPS spectrum in TON is divided into three species, Ti–O–Ti bonding of lattice oxygen (O L ) at 530.1 eV, OH groups on the surface (O OH ) at 532.3 eV, and C–O bonding (O C ) at 534 eV caused by surface contaminants in air, respectively .…”

Section: Resultsmentioning

confidence: 99%

TiO_xN_y/TiO₂ Photocatalyst for Hydrogen Evolution under Visible Light Irradiation II Degradation of Photocatalytic Activity of TiO_xN_y/TiO₂ with Mild Oxidation

et al. 2019

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We have studied degradation of photocatalytic activity of TiOxNy for water splitting under visible light irradiation with heat treatment in O2/N2 mixed gas. The reduction of the N content by oxidation through the formation of O–N–O species (NOx) was confirmed as the result of the reduction of the catalytic activity. The catalytic activity is not simply related to the amount of N remained but that of N taking the chemical state of O–Ti–N in TiOxNy, which is the active species for visible light responsiveness on hydrogen evolution. N in TiOxNy is first oxidized to NO2 species during the oxidation, which reduces the activity. Then, O–N–O species (NOx) is removed as NOx gas from the surface. Because the formation of O–N–O in TiOxNy could induce an impurity energy level to enhance charge recombination, the loss of catalytic activity might be influenced by the formation of O–N–O species (NOx) rather than the loss of the N content from TiOxNy.

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Section: Resultsmentioning

confidence: 99%

TiO_xN_y/TiO₂ Photocatalyst for Hydrogen Evolution under Visible Light Irradiation II Degradation of Photocatalytic Activity of TiO_xN_y/TiO₂ with Mild Oxidation

et al. 2019

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“…Here, the local concentrations of (N)s and (NO 2 )s in both A‐cat and I‐cat were quantified as following. We have attempted to reproduce the depth‐resolved N K‐edge ELNES (in Figure A,B) by superposition of XANES of A‐cat and I‐cat with a suitable ratio . The attempt was limited within the near‐edge region of ELNES, because the multiple loss due to the sample thickness disturbed the reproduction in the post‐edge region of the ELNES.…”

Section: Resultsmentioning

confidence: 99%

“…We have attempted to reproduce the depth-resolved N K-edge ELNES (in Figure 4A,B) by superposition of XANES of A-cat and I-cat with a suitable ratio. [21][22][23][24] The attempt was limited within the near-edge region of ELNES, because the multiple loss due to the sample thickness disturbed the reproduction in the post-edge region of the ELNES. the integrated amount of (N)s within around 100 nm is nearly three times larger for the former than that for the latter, which well corresponds to the difference of the photocatalytic activity between the two.…”

Section: Introductionmentioning

confidence: 99%

Quantitative XAFS/EELS analyses of nitrogen species in titanium oxide photocatalysts

Yoshida

Yamamoto

Akatsuka

et al. 2018

Surface & Interface Analysis

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With a view to rational designing of a highly functional visible‐light TiO2 photocatalyst, nitrogen atoms were doped into TiO2 samples by an ion implantation technique which enables to control the depth and concentration of dopants. Although the absorbance in the visible‐light region of the sample increased by the nitrogen doping, photocatalytic activity of the sample was not directly connected with the photo‐absorbance. The N K‐edge X‐ray absorption near edge structure (XANES) spectrum of the photocatalytic active sample (A‐cat) showed a characteristic double peak at 398 and 401 eV, and the XANES spectrum of the inactive sample (I‐cat) a distinct single peak around 401 eV. These features of the XANES spectra were well reproduced by theoretical simulations based on the model where an O atom in TiO2 was replaced by N ((N)s) for A‐cat, and that of quasi NO2 molecule ((NO2)s) for I‐cat. Therefore, we have concluded that the nitrogen atom occupying the oxygen site of TiO2 is photocatalytic active species effective for visible light photocatalysis. In addition, the quantitative XANES/ELNES analysis has revealed that the photo‐absorbance ratio of I‐cat to A‐cat corresponds well to the ratio of total doped nitrogen concentration rather than photocatalytic active nitrogen ((N)s) concentration. This result indicates that not only (N)s but also (NO2)s also absorb the visible light. Thus, the absorbance in the visible‐light region is not necessarily an indication of the visible‐light response of a photocatalyst.

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Depth distribution of dopant effective for visible‐light response in nitrogen‐doped TiO₂ photocatalyst

Yoshida

Kuda²,

Muto

2014

Surface & Interface Analysis

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Nitrogen was doped into TiO2 by an ion implantation technique to investigate the depth distribution of nitrogen most effective for fabricating a visible‐light responsive photocatalyst. In the nitrogen‐doped TiO2 samples, the photocatalytic activity under visible‐light irradiation was enhanced, wherein two types of chemical state of nitrogen, one photocatalytically active and the other inactive, were found depending on the nitrogen concentration, using electron energy loss spectroscopy. The depth distributions of nitrogen were quantified, so that the implanted nitrogen increased with thickness from the surface up to 90 nm, consistent with Monte Carlo simulations. The critical nitrogen concentration for the photocatalytically active species to form was estimated to be no higher than 1.8 atom%. We also derived semi‐empirical equations from the present results to estimate the critical depth of nitrogen distribution effectively reactive to be 13 ± 5 nm from the surface. Copyright © 2014 John Wiley & Sons, Ltd.

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Nitrogen doped TiO2 photocatalyst prepared by low energy N+ implantation technique

Cited by 5 publications

References 5 publications

TiO_xN_y/TiO₂ Photocatalyst for Hydrogen Evolution under Visible Light Irradiation II Degradation of Photocatalytic Activity of TiO_xN_y/TiO₂ with Mild Oxidation

TiO_xN_y/TiO₂ Photocatalyst for Hydrogen Evolution under Visible Light Irradiation II Degradation of Photocatalytic Activity of TiO_xN_y/TiO₂ with Mild Oxidation

Quantitative XAFS/EELS analyses of nitrogen species in titanium oxide photocatalysts

Depth distribution of dopant effective for visible‐light response in nitrogen‐doped TiO₂ photocatalyst

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Nitrogen doped TiO2 photocatalyst prepared by low energy N+ implantation technique

Cited by 5 publications

References 5 publications

TiOxNy/TiO2 Photocatalyst for Hydrogen Evolution under Visible Light Irradiation II Degradation of Photocatalytic Activity of TiOxNy/TiO2 with Mild Oxidation

TiOxNy/TiO2 Photocatalyst for Hydrogen Evolution under Visible Light Irradiation II Degradation of Photocatalytic Activity of TiOxNy/TiO2 with Mild Oxidation

Quantitative XAFS/EELS analyses of nitrogen species in titanium oxide photocatalysts

Depth distribution of dopant effective for visible‐light response in nitrogen‐doped TiO2 photocatalyst

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TiO_xN_y/TiO₂ Photocatalyst for Hydrogen Evolution under Visible Light Irradiation II Degradation of Photocatalytic Activity of TiO_xN_y/TiO₂ with Mild Oxidation

TiO_xN_y/TiO₂ Photocatalyst for Hydrogen Evolution under Visible Light Irradiation II Degradation of Photocatalytic Activity of TiO_xN_y/TiO₂ with Mild Oxidation

Depth distribution of dopant effective for visible‐light response in nitrogen‐doped TiO₂ photocatalyst