Influence of Thermal Treatment on the Adsorption of Oxygen and Photocatalytic Activity of TiO<sub>2</sub>

Yu, Jimmy C.; Lin, Jun; Lo, and D.; Lam, S. K.

doi:10.1021/la000309w

Cited by 119 publications

(70 citation statements)

References 29 publications

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“…As the H 2 treatment temperature was above 400°C, the peak with a g factor of 2.003 could be assigned to the OV, which was similar to the OV observed in ZrO 2 during the thermal treatment by air (Torralvo et al, 1984). It is also noted that the peaks with a g factor of 2.003 at the temperatures below 300°C became more negative and could be assigned to the O À 2 , since the O À 2 species came from the adsorbed oxygen on the TiO 2 surface (Yu et al, 2000). However, it was found that some peaks appeared again in the EPR spectra due to oxidation reaction, after the H 2 -treated TiO 2 samples were exposed to air for a while.…”

Section: Reason Causing the Enhancement Of Photocatalytic Activity Bysupporting

confidence: 70%

The enhancement of TiO2 photocatalytic activity by hydrogen thermal treatment

et al. 2003

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In this study, conventional TiO 2 powder was heated in hydrogen (H 2 ) gas at a high temperature as pretreatment. The photoactivity of the treated TiO 2 samples was evaluated in the photodegradation of sulfosalicylic acid (SSA) in aqueous suspension. The experimental results demonstrated that the photodegradation rates of SSA were significantly enhanced by using the H 2 -treated TiO 2 catalysts and an optimum temperature for the H 2 treatment was found to be of 500-600°C. The in situ electron paramagnetic resonance (EPR) signal intensity of oxygen vacancies (OV) and trivalent titanium (Ti 3þ ) associated with the photocatalytic activity was studied. The results proved the presence of OV and Ti 3þ in the lattice of the H 2 -treated TiO 2 and indicated that both were contributed to the enhancement of photocatalytic activity. Moreover, the experimental results presented that the EPR signal intensity of OV and Ti 3þ in the H 2 -treated TiO 2 samples after 10 months storage was still significant higher than that in the untreated TiO 2 catalyst. The experiment also demonstrated that the significant enhancement occurred in the photodegradation of phenol using the H 2 -treated TiO 2 .

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Section: Reason Causing the Enhancement Of Photocatalytic Activity Bysupporting

confidence: 70%

The enhancement of TiO2 photocatalytic activity by hydrogen thermal treatment

et al. 2003

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“…Ionic superoxide radicals can be easily generated on TiO 2 by a number of methods including 1) by contact with H 2 O 2 , [44] 2) by direct O 2 adsorption on thermally reduced samples, [21,22,24] and, by far the most commonly used method, 3) by photoadsorption. [19,27,28,39,[45][46][47] In methods 2) and 3) the radicals are formed at the gas/solid interface and they are reasonably stable at room temperature provided the sample is kept under vacuum and free from other surface adsorbates, [24] particularly OH groups and water. In this study, the superoxide radicals were formed either by method 2 involving O 2 exposure of the reduced TiO 2 sample, or by method 3 involving photoirradiation of adsorbed oxygen on an activated TiO 2 sample.…”

Section: Formation Of Transient Peroxy Radicals With Other Ketonesmentioning

confidence: 99%

Free‐Radical Pathways in the Decomposition of Ketones over Polycrystalline TiO₂: The Role of Organoperoxy Radicals

2006

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The oxidative decomposition of various ketones (including acetone, 2-butanone, 4-heptanone, cyclopentanone and cyclohexanone) over dehydrated TiO(2) (P25) powder is investigated by electron paramagnetic resonance (EPR) spectroscopy. For the first time, a series of thermally unstable radical intermediates are observed both on the activated and reduced TiO(2) surface, depending on the adopted experimental conditions. These radical intermediates are identified as organoperoxy-based species of general formula ROO(.-) and RCO(3) (.-). They are formed by reaction of photogenerated charge carriers (either trapped electrons or trapped holes) with the adsorbed ketones in the presence of molecular oxygen. The organoperoxy intermediates are thermally unstable and decompose at temperatures in the region of 180-250 K. This work demonstrates that free-radical pathways involving both organoperoxy and superoxide radicals can be responsible for the thermal- and photodecomposition of ketones over polycrystalline TiO(2) (P25).

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“…H 2 O 2 -oxidized and hot water aged Ti has previously been shown to generate an abundance of Ti-OH groups at the surface, contributing to the ability of apatite formation [15,26]. Such surface groups also benefit the photocatalytic reaction by increasing oxygen adsorption and preventing electron-hole recombination [38][39][40].…”

Section: Discussionmentioning

confidence: 99%

Stability and prospect of UV/H2O2 activated titania films for biomedical use

Unosson

Welch

Persson

et al. 2013

Applied Surface Science

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Biomedical implants and devices that penetrate soft tissue are highly susceptible to infection, but also accessible for UV induced decontamination through photocatalysis if coated with suitable surfaces. As an on-demand antibacterial strategy, photocatalytic surfaces should be able to maintain their antibacterial properties over repeated activation. This study evaluates the surface properties and photocatalytic performance of titania films obtained by H 2 O 2 -oxidation and heat treatment of Ti and Ti-6Al-4V substrates, as well as the prospect of assisting photocatalytic reactions with H 2 O 2 for improved efficiency. H 2 O 2 -oxidation generated a nanoporous coating, and subsequent heat treatment above 500°C resulted in anatase formation. Tests using photo-assisted degradation of rhodamine B showed that prior to heat treatment, an initially high photocatalytic activity (PCA) of H 2 O 2 -oxidized substrates decayed significantly with repeated testing. Heat treating the samples at 600°C resulted in stable yet lower PCA. Addition of 3% H 2 O 2 during the photo-assisted reaction led to a substantial increase in PCA due to synergetic effects at the surface and H 2 O 2 photolysis, the effect being most notable for non-heat treated samples. Both heat treated and non-heat treated samples showed stable PCA through repeated tests with H 2 O 2 -assisted photocatalysis, indicating that the combination of H 2 O 2 -oxidized titania films, UV light and added H 2 O 2 can improve efficiency of these photocatalytic surfaces. Highlights Ti and Ti64 substrates were surface modified by H 2 O 2 -oxidation and heat treatments. TiO 2 /UV/H 2 O 2 synergy effects significantly boosted rhodamine B degradation. 3% H 2 O 2 addition increased stability over repeated use.

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Influence of Thermal Treatment on the Adsorption of Oxygen and Photocatalytic Activity of TiO₂

Cited by 119 publications

References 29 publications

The enhancement of TiO2 photocatalytic activity by hydrogen thermal treatment

The enhancement of TiO2 photocatalytic activity by hydrogen thermal treatment

Free‐Radical Pathways in the Decomposition of Ketones over Polycrystalline TiO₂: The Role of Organoperoxy Radicals

Stability and prospect of UV/H2O2 activated titania films for biomedical use

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Influence of Thermal Treatment on the Adsorption of Oxygen and Photocatalytic Activity of TiO2

Cited by 119 publications

References 29 publications

The enhancement of TiO2 photocatalytic activity by hydrogen thermal treatment

The enhancement of TiO2 photocatalytic activity by hydrogen thermal treatment

Free‐Radical Pathways in the Decomposition of Ketones over Polycrystalline TiO2: The Role of Organoperoxy Radicals

Stability and prospect of UV/H2O2 activated titania films for biomedical use

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Influence of Thermal Treatment on the Adsorption of Oxygen and Photocatalytic Activity of TiO₂

Free‐Radical Pathways in the Decomposition of Ketones over Polycrystalline TiO₂: The Role of Organoperoxy Radicals