Electron–Hole Recombination Time at TiO2 Single-Crystal Surfaces: Influence of Surface Band Bending

Ozawa, K.; Emori, Masato; Yamamoto, Susumu; Yukawa, Ryu; Yamamoto, Shingo; Hobara, Rei; Fujikawa, K.; Sakama, Hiroshi; Matsuda, Iwao

doi:10.1021/jz500770c

Cited by 231 publications

(178 citation statements)

References 28 publications

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“…In contrast, R of the samples with the oxidation time of 50 h is higher than that of 3 h, which is below that at temperatures from 573 to 1073 K. The photocatalytic activity of samples might depend on the crystal structure and morphology, which could be controlled by changing the oxidation condition. With the growth of the anatase phase of samples, the photocatalytic activity is the highest at the temperature of 673 K with almost anatase TiO2, because anatase is a better photocatalyst than rutile [45]. When increasing the temperature, phase transformation from anatase to rutile would occur.…”

Section: Influence On Photocatalyst Coatings Of Tio2 By Oxidation Conmentioning

confidence: 99%

Review on the Photocatalyst Coatings of TiO2: Fabrication by Mechanical Coating Technique and Its Application

Guan

Líu

et al. 2015

Coatings

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This review presents the latest results of studies directed at photocatalyst coatings of titanium dioxide (TiO2) prepared by mechanical coating technique (MCT) and its application. Compared with traditional coating techniques, MCT is a simple, low cost and useful coating formation process, which is proposed and developed based on mechanical frictional wear and impacts between substrate materials and metal powder particles in the bowl of planetary ball mill. The formation process of the metal coatings in MCT includes four stages: The nucleation by adhesion, the formation and coalescence of discrete islands, formation and thickening of continuous coatings, exfoliation of continuous coatings. Further, two-step MCT was developed based on the MCT concept for preparing composite coatings on alumina (Al2O3) balls. This review also discusses the influence on the fabrication of photocatalyst coatings after MCT and improvement of its photocatalytic activity: oxidation conditions, coating materials, melt salt treatment. In this review, the oxidation conditions had been studied on the oxidation temperature of 573 K, 673 K, 773 K, 873 K, 973 K, 1173 K and 1273 K, the oxidation time of 0.5 h, 1 h, 3 h, 10 h, 15 h, 20 h, 30 h, 40 h, and 50 h. The photocatalyst coatings showed the highest photocatalytic activity with the oxidation condition of 1073 K for 15 h. The metal powder of Ti, Ni and Cr had been used as the coating materials. The composite metal powder could affect the surface structure and photocatalytic OPEN ACCESSCoatings 2015, 5 426 activity. On the other hand, the melt salt treatment with KNO3 is an effective method to form the nano-size structure and enhance photocatalytic activity, especially under visible light.

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Section: Influence On Photocatalyst Coatings Of Tio2 By Oxidation Conmentioning

confidence: 99%

Review on the Photocatalyst Coatings of TiO2: Fabrication by Mechanical Coating Technique and Its Application

Guan

Líu

et al. 2015

Coatings

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“…When XR is lower, the charge transfer would be limited, as a low content of rutile phase could not effectively enhance the photocatalytic activity [23]. However, too much rutile phase would absorb much of the energy from the light, which would also inhibit the activity, as the photocatalytic activity of rutile phase is lower than that of anatase phase [38][39][40]. Apart from the synergistic effect of the mixed-phase, another possible reason for the enhancement of photocatalytic activity is that a certain amount of Ti 3+ surface states or cation vacancies have been formed to maintain the electroneutrality by Cr 3+ substituting Ti 4+ [41].…”

Section: Photocatalytic Activity Of Photocatalyst Composite Coatingsmentioning

confidence: 99%

Fabrication of Photocatalyst Composite Coatings of Cr-TiO2 by Mechanical Coating Technique and Oxidation Process

Guan

Líu

et al. 2015

Coatings

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Abstract:The photocatalyst composite coatings on alumina (Al2O3) balls had been prepared by mechanical coating technique (MCT) with titanium (Ti) powder, adding a certain content of chromium (Cr) powder and a subsequent oxidation process. The effect of oxidation conditions and adding Cr on the composite coatings of chromium-titanium dioxide (Cr-TiO2) was investigated. The results show Cr-TiO2 coatings are with mixed-phase of anatase and rutile under different oxidation conditions, and the mass fraction of the rutile phase (XR) has been obviously increased when under 973 K. The SEM images indicate that adding Cr could significantly accelerate the growth of surface structures, especially at 1073 K. The photocatalytic activity of Cr-TiO2 coatings firstly increases, then decreases, with the addition of Cr. Compared with that of two other oxidation conditions, the enhancement on photocatalytic activity by adding Cr under visible light is relatively higher, especially at 973 K for 10 h.

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“…However, they also have disadvantages, such as the recombination of a generated redox environment, their absorption of a small amount of the UV light irradiation, a large band gap, and low selectivity [4] [5]. Therefore, TiO 2 -based semiconductors have been of great interest, and great efforts have been made to fabricate and design an ideal structure for TiO 2 -based semiconductors to improve the efficiency of the TiO 2 nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Photodegradation of Binary Azo Dyes Using Core-Shell Fe3O4/SiO2/TiO2 Nanospheres

Alzahrani¹

2017

AJAC

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Photodegradation has emerged as an environmentally friendly method of decomposing harmful dyes in wastewater. In this study, core-shell Fe 3 O 4 /SiO 2 / TiO 2 nanospheres with magnetic cores were obtained from synthesised magnetic Fe 3 O 4 nanoparticles through the precipitation method, the surface of the magnetic Fe 3 O 4 nanoparticles was coated with a silica (SiO 2 ) layer by hydrolysis of tetramethoxysilane (TMOS) as a silica source, and finally, Fe 3 O 4 /SiO 2 nanospheres were coated with titanium (TiO 2 ) layer using tetrabutyltitanate (TBT) as a precursor through the sol-gel process. The morphology and structure of the prepared materials were characterised by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), X-ray energy dispersive spectrometry (EDAX), Fourier transform infrared spectroscopy (FT-IR), and atomic force microscopy (AFM). The photocatalytic activities of the prepared core-shell nanospheres were studied using binary azo dyes, namely methyl orange (anionic dye, MO) and methylene blue (cationic dye, MB) in aqueous solution under UV light irradiation (365 nm), and UV-Vis spectrophotometer was utilised to monitor the amount of each dye in the mixture. It was found that 90.2% and 100% of binary MO and MB were removed for 5 h, respectively. The results revealed that the efficiency of the photocatalytic degradation of the core-shell nanospheres was not degreased after five runs that can be used as recyclable photocatalysts. The results show that the performance of the prepared core-shell nanospheres was better than that of commercial TiO 2 nanoparticles. Moreover, the magnetic separation properties of the core-shell Fe 3 O 4 /SiO 2 /TiO 2 nanospheres can enable the prepared materials to have wider application prospects.

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Electron–Hole Recombination Time at TiO₂ Single-Crystal Surfaces: Influence of Surface Band Bending

Cited by 231 publications

References 28 publications

Review on the Photocatalyst Coatings of TiO2: Fabrication by Mechanical Coating Technique and Its Application

Review on the Photocatalyst Coatings of TiO2: Fabrication by Mechanical Coating Technique and Its Application

Fabrication of Photocatalyst Composite Coatings of Cr-TiO2 by Mechanical Coating Technique and Oxidation Process

Photodegradation of Binary Azo Dyes Using Core-Shell Fe<sub>3</sub>O<sub>4</sub>/SiO<sub>2</sub>/TiO<sub>2</sub> Nanospheres

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Electron–Hole Recombination Time at TiO2 Single-Crystal Surfaces: Influence of Surface Band Bending

Cited by 231 publications

References 28 publications

Review on the Photocatalyst Coatings of TiO2: Fabrication by Mechanical Coating Technique and Its Application

Review on the Photocatalyst Coatings of TiO2: Fabrication by Mechanical Coating Technique and Its Application

Fabrication of Photocatalyst Composite Coatings of Cr-TiO2 by Mechanical Coating Technique and Oxidation Process

Photodegradation of Binary Azo Dyes Using Core-Shell Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt;/SiO&lt;sub&gt;2&lt;/sub&gt;/TiO&lt;sub&gt;2&lt;/sub&gt; Nanospheres

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Electron–Hole Recombination Time at TiO₂ Single-Crystal Surfaces: Influence of Surface Band Bending

Photodegradation of Binary Azo Dyes Using Core-Shell Fe<sub>3</sub>O<sub>4</sub>/SiO<sub>2</sub>/TiO<sub>2</sub> Nanospheres