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Кузнецов, В. Н.; Malkin, M. G.

doi:10.1023/a:1004139127598

Cited by 7 publications

(12 citation statements)

References 8 publications

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“…25 It is reported that in the N-doped TiO 2 case the absorption o500 nm is due to the additional states brought by the N near the valence band edge, while the absorption 4500 nm is explained with doping-induced defects and oxygen vacancies. [26][27][28][29][30] We believe that this explanation is also applicable for the N-doped CeO 2 nanoparticles.…”

Section: Resultsmentioning

confidence: 64%

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Synthesis, characterization and computational study of nitrogen-doped CeO2 nanoparticles with visible-light activity

Mao

Zhao

Qiu

et al. 2008

Phys. Chem. Chem. Phys.

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Nitrogen-doped CeO2 nanoparticles were synthesized through a wet-chemical route. Nitrogen has been successfully incorporated into CeO2 nanoparticles and the nitrogen-doping level was also successfully controlled. The optical properties due to the different N-doping levels in CeO2 nanoparticles were characterized by UV-Vis diffuse reflectance spectroscopy (DRS), which showed a visible-light absorbance shift. The resulting nanoparticles show enhanced visible-light sensitivity and photocatalytic activity compared to undoped CeO2 nanoparticles. DFT calculations were performed to explore the effect of nitrogen doping versus oxygen vacancies. The calculations show that the change of the electronic structure upon N-doping CeO2 is quite different from that of N-doped TiO2, which has been studied extensively.

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Section: Resultsmentioning

confidence: 64%

“…To further explore the causes for the visible-light absorption, a recently introduced difference DRS analysis [27][28][29][30] was applied in this study. The difference DRS spectra demonstrate the treatment-induced spectral changes.…”

Section: Resultsmentioning

confidence: 99%

Synthesis, characterization and computational study of nitrogen-doped CeO2 nanoparticles with visible-light activity

Mao

Zhao

Qiu

et al. 2008

Phys. Chem. Chem. Phys.

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“…The aim of this study was to investigate TiO 2 absorption spectra in the visible light region. In our earlier study of the diffuse reflectance spectra (DRS's) of powdered compositions of TiO 2 / polymers, we reported that light absorption by these systems originated (i) only in the visible spectral region and (ii) after subjecting them to a relatively low-temperature heat treatment above 350 K . Comparison of the absorption spectra of such compositions with spectra of powdered samples of TiO 2 reduced in H 2 or CO environments permitted assignments of the absorption features to defects associated with oxygen vacancies in TiO 2 .…”

Section: Introductionmentioning

confidence: 99%

Visible Light Absorption by Various Titanium Dioxide Specimens

2006

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A set of heat-induced and photoinduced absorption spectra of various compositions of Degussa P25 TiO2 and different polymers has been examined. The spectra are described as the sum of overlapping absorption bands (ABs) with maxima at 2.90 eV (427 nm, AB1), 2.55 eV (486 nm, AB2), and 2.05 eV (604 nm, AB3); the spectra correlate entirely with the experimentally observed absorption spectra after the reduction of TiO2. Absorption spectra of visible-light-active TiO2 photocatalysts reported recently in the literature have also been analyzed. Relatively narrow absorption spectra are very similar and independent of the method of photocatalyst preparation. The average absorption spectrum can be described reasonably well by the sum of the two absorption bands AB1 and AB2. It is argued that visible light activation of TiO2 specimens (anion-doped or otherwise) implicates defects associated with oxygen vacancies that give rise to color centers displaying these absorption bands and not to a narrowing of the original band gap of TiO2 (EBG approximately 3.2 eV, anatase) through mixing of dopant and oxygen states, as has been suggested recently in the literature.

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“…These results indicate that increasing N content in the metal oxides enhances the visible-light absorption of the N-doped nanoparticles. In order to explore the origin of the visible-light absorption, a recently introduced difference DRS analysis technique [21][22][23] developed for N-doped TiO 2 has been used in this study. The difference DRS data (Dq) have been obtained by subtracting the reflectance spectra of non-doped metal oxides from the spectra of doped metal oxides.…”

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confidence: 99%

“…The obtained Dq were normalized and plotted versus the wavelength. The difference absorption spectra show the absorption induced by N doping [21,22]. The photodegradation of methylene blue catalyzed by N-doped and undoped metal oxides was measured using the sensitization process in the visible range at k > 400 nm [23].…”

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confidence: 99%

Synthesis and Characterization of Nitrogen‐Doped Group IVB Visible‐Light‐Photoactive Metal Oxide Nanoparticles

2007

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The incorporation of main group elements into wide-bandgap semiconductors has attracted significant interest because of the potential for modifying the physical properties of these semiconductors, as well as for applications such as photocatalysis, water splitting, and optoelectronics. [1][2][3] Among the main group elements, nitrogen is believed to be the most favorable p-type dopant because of its similar size to oxygen, metastable AX center formation, and small ionization energy.[4] For example, the incorporation of N into ZnO has been found to be a very promising way to make p-type ZnO, which represents a potentially useful alternative to toxic and expensive III-V semiconductors for applications such as light-emitting devices (LEDs). [2,5,6] Another exciting example is visible-light-active TiO 2 , which is a promising material for applications such as water splitting and photocatalysis. [1,[7][8][9][10] Owing to its potential role in solving the inevitable global energy and environment crises, N-doped TiO 2 has received a great deal of attention in recent years. Although several theoretical and experimental studies have validated the efficacy of the N doping of TiO 2 for a variety of applications, [1,8,[10][11][12][13][14][15][16][17] the different approaches used for N doping have raised questions about the origin of the observed photocatalytic activity. In order to increase the understanding of N doping at the nanoscale level, it is imperative to carry out a systematic analysis of the photocatalytic activities of nanoparticles with different N-doping levels and metal oxide matrices to aid the development of a new generation of photocatalysts. [18,19] However, from a survey of the literature, no such study has been conducted up till now. Here, we present the incorporation of controlled amounts of N into group IVB metal oxide (TiO 2 , ZrO 2 , and HfO 2 ) nanoparticles via a reliable wet-chemical procedure under ambient conditions. Furthermore, we present the effects of doping on their optical and photocatalytic properties. The synthesis of N-doped group IVB metal oxides is based on our previously reported sol-gel approach. [8,9,20] We have determined from the X-ray photoelectron spectroscopy (XPS) analysis of N-doped TiO 2 [9,20] that coordinating the amine precursor to the Ti precursor (usually Ti[OCH 2 (CH 3 ) 2 ] 4 ) is essential for the efficient N doping of metal oxides. In the present synthetic route, we first attach the amine to the central metal to form an amino-coordinated precursor complex; subsequently, we hydrolyze the precursor solution with distilled water. Under different pH conditions it is possible to obtain TiO 2 slurries with different amounts of incorporated nitrogen. In addition, the particle size can be confined to the nanometer regime by controlling the rate of water addition. After washing, the dispersions are centrifuged and the obtained powders are dried under vacuum. The dried powders are yellow to orange in color depending on the doping level. Before characterization, the products ...

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Cited by 7 publications

References 8 publications

Synthesis, characterization and computational study of nitrogen-doped CeO2 nanoparticles with visible-light activity

Synthesis, characterization and computational study of nitrogen-doped CeO2 nanoparticles with visible-light activity

Visible Light Absorption by Various Titanium Dioxide Specimens

Synthesis and Characterization of Nitrogen‐Doped Group IVB Visible‐Light‐Photoactive Metal Oxide Nanoparticles

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