Influence of oxidation process on photocatalytic activity of photocatalyst coatings by mechanical coating technique

Lu, Yun; Kobayashi, Keita; Hao, Liang; Yoshida, Hiroyuki; Asanuma, Hiroshi; Chen, Jinxiang

doi:10.1016/j.mssp.2014.10.004

Cited by 17 publications

(12 citation statements)

References 27 publications

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“…In contrast, the M10-xK-yh samples appear to have various colors, under different oxidation conditions, as shown in Figure 22. The color of TiO2 is related to the thickness of TiO2 coatings if the thickness is nano-sized, which hints the samples of TiO2 coatings with different thicknesses and nano-sizes were formed by each oxidation condition [27,36]. Figure 23 shows the XRD patterns of the photocatalyst coatings on Al2O3 balls.…”

Section: Influence On Photocatalyst Coatings Of Tio2 By Oxidation Conmentioning

confidence: 98%

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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: 98%

“…With the subsequent oxidation process, the Ti coatings are oxidized to form TiO2 coatings or TiO2/Ti composite coatings, shown as Figure 2 [26]. The improvement of photocatalytic activity of TiO2 coatings via the ions of transition metal and/or the mixed-phase had been studied in detail [27][28][29].…”

Section: Introductionmentioning

confidence: 99%

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

Guan

Líu

et al. 2015

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“…When increased the oxidation temperature from 973 K to 1073 K for 3 h, the XR obviously changes from anatase to rutile; when the oxidation time is extended from 3 h to 10 h at 973 K, the XR does not change much, compared with increasing the temperature. According to the Gibbs' free energy for the two phases (anatase and rutile), the energy difference ΔG between phase of anatase and rutile at 973 K and 1073 K are about 2761 J·mol , respectively, calculated by the equations [29], while the effect of extending oxidation time (3 h to 50 h) or adding Cr would accelerate the process of crystal growth or phase transformation [30,31]. Considering these three factors based on the above results, the effect on phase transformation and crystal growth by the oxidation temperature is more direct than that of oxidation time or adding Cr.…”

Section: Appearance and Phase Evolution Of Photocatalyst Composite Comentioning

confidence: 99%

“…Considering the changes of surface microstructure and phase transformation, one could draw the conclusion that the phase transformation from anatase to rutile has been effected by the crystal size [31,32]. During each oxidation condition, Cr could accelerate the phase transformation from anatase to rutile, and affect the growth of crystal size, especially at suitable temperature of 973 K [25,30]. However, comprehensive comparison of Figures 3-5, the effect of oxidation temperature on the change of microstructure is more significant than that of oxidation time or the content of adding Cr, as the ΔG is too high at 1073 K. …”

Section: Appearance and Phase Evolution Of Photocatalyst Composite Comentioning

confidence: 99%

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

Guan

Líu

et al. 2015

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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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“…TiO 2 also known as road warrior as to clean the nitrogen oxide (NO x ) in the air that was produced by vehicles emissions 4) . Various techniques have been used to fabricate TiO 2 coating for photocatalyst applications including chemical vapor deposition (CVD), physical vapor deposition (PVD), dip-coating and sol gel method [5][6][7][8] . However, these methods have some restrictions such as high production cost and complex large-scale equipment 5) .…”

Section: Introductionmentioning

confidence: 99%

Effect of Powder Calcination on the Cold Spray Titanium Dioxide Coating

et al. 2016

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The agglomeration of nanoparticles is usually undesirable in the formation of powder. However, a coating process using the cold spray method only allows the usage of micrometer-sized feedstock powder in a regular powder feeder. In this study, TiO 2 coatings on ceramic tiles were prepared by a cold spray process using agglomerated TiO 2 powders synthesized via a simple hydrolysis method. XRD analysis showed that TiO 2 powders, composed of anatase phase and calcination at 200 C to 400 C, resulted in enhanced crystallinity and crystallite size of the anatase TiO 2 powders. SEM micrographs revealed that the obtained powders were in spherical-like agglomerates with the tertiary particles having diameters of 5-20 µm. TEM image revealed that the obtained TiO 2 powders were composed of nanometer primary particles. XPS analyses showed that TiO 2 powders without calcination and calcined at different temperatures were formed through the Ti-O bonds. The in uences of post treatment at low calcination temperatures of the as-synthesized TiO 2 powders were studied on powder deposition. The results of this study indicated that a post treatment on TiO 2 powder improved powder deposition on ceramic tile substrate via the cold spray method. The cross-section of the obtained coating which was observed using SEM showed that nanoparticles TiO 2 powders in the agglomerated form were able to be deposited on the substrate and formed a thick coating. A stacking of agglomerated TiO 2 powders was found on the cross-section observation which is due to the breaking up of ceramic particles which was induced by porosity in the powder and is believed to be responsible for the formation of the coating.

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Influence of oxidation process on photocatalytic activity of photocatalyst coatings by mechanical coating technique

Cited by 17 publications

References 27 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

Effect of Powder Calcination on the Cold Spray Titanium Dioxide Coating

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