Effect of surface hydroxyl density on photocatalytic oxygen generation in aqueous TiO2 suspensions

Oosawa, Yoshinao; Grätzel, Michaël

doi:10.1039/f19888400197

Cited by 93 publications

(62 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…However, on the other hand, the apparent rate of photocatalytic Ag deposition was enhanced by calcination at a higher temperature as shown in Figure 5c. Similar results for this reaction have been observed in commercial TiO 2 samples 42 and TiO 2 samples prepared by hydrolysis of titanium isopropoxide, 33 although the rate was decreased by severe calcination at 973-1173 K because of a drastic decrease in their BET surface areas. The effect of calcination on the recombination rate for HyCOM-A was also examined by femtosecond pump-probe diffuse reflectance measurements, and it has been shown that the recombination rate was drastically decreased upon calcination.…”

Section: Resultssupporting

confidence: 80%

Correlation between Some Physical Properties of Titanium Dioxide Particles and Their Photocatalytic Activity for Some Probe Reactions in Aqueous Systems

et al. 2002

View full text Add to dashboard Cite

Nanocrystalline anatase titanium(IV) oxide (TiO 2 ) particles were synthesized by hydrothermal crystallization in organic media (HyCOM) followed by calcination at various temperatures up to 1273 K, and they were characterized by analysis of surface adsorption of the substrates, as well as by X-ray diffraction (XRD) and Brunauer-Emmet-Teller (BET) surface area measurements. These HyCOM TiO 2 samples were used for three kinds of photocatalytic reactions: mineralization of acetic acid (AcOH) in aerated aqueous suspensions, dehydrogenation of 2-propanol (2-PrOH) by in situ platinized powders, and silver-metal deposition from silver ions (Ag + ) in deaerated aqueous suspensions of bare TiO 2 samples. Dependence of the photocatalytic activities on calcination temperature (T c ) and on the amount of adsorbed substrates in each reaction and correlations with the physical properties of HyCOM TiO 2 were examined. In the case of mineralization of AcOH, the activitiy of each sample was almost proportional to the amount of surface-adsorbed AcOH in the dark, and the uncalcined (as-prepared) HyCOM TiO 2 showed the highest activity, which was monotonically reduced with T c , that is, with decrease in the amount of surface-adsorbed AcOH. On the other hand, in the case of silver-metal deposition, the photocatalytic activity was enhanced by calcination at higher temperature, despite the simultaneous decrease in the amount of surface-adsorbed Ag + in the dark. Overall, the effects of calcination on the photocatalytic activities for several reaction systems strongly suggested that photocatalytic activity depends on two significant factors, adsorbability and recombination probability, corresponding to the specific surface area and crystallinity, respectively, and that the balance of these two factors determines the T c dependence.

show abstract

Section: Resultssupporting

confidence: 80%

Correlation between Some Physical Properties of Titanium Dioxide Particles and Their Photocatalytic Activity for Some Probe Reactions in Aqueous Systems

et al. 2002

View full text Add to dashboard Cite

show abstract

“…Results and discussion 3.1 Direct formation of TiO 2 /SiO 2 composite nanoparti cles The hydrolyses of acidic mixed solutions of TiOSO 4 and TEOS were carried out under hydrothermal conditions at 200 C for 24 h. Table 1 shows the compositions of the as prepared powders that were directly precipitated from the precursor solutions of TiOSO 4 and TEOS having a metal cation concentration of 0.2 mol/dm 3 with various ratios of Ti/ Si, by thermal hydrolysis. The XRD patterns for the as prepared samples are shown in Fig.…”

Section: Sample Characterizationmentioning

confidence: 99%

“…Summary TiO 2 /SiO 2 composite nanoparticles consisting of nanosized (1416 nm) anatase and amorphous silica were directly formed from acidic precursor solutions of TiOSO 4 and TEOS by thermal hydrolysis at 200 C. The composite nanoparticles possessed enhanced photocatalytic activity for the decomposi tion of MB and removal of NO gas. The asprepared compo site nanoparticles showed the highest photoactivity for MB decomposition when the SiO 2 content was 25.1 mol÷.…”

Section: Sample Characterizationmentioning

confidence: 99%

“…24) Although wet chemical synthesis routes have been widely used to prepare nanocrystalline particles, SiO 2 containing titania has been mostly prepared by the solgel method. The present study was aimed at the investigation of the direct formation of anatasetype TiO 2 /SiO 2 composite nanoparticles from acidic precursor solutions of TiOSO 4 and tetraethylorthosilicate by hydrolysis under mild hydro thermal conditions. The effect of the presence of SiO 2 on the photoactivity of the hydrothermal anatase particles for the decomposition of methylene blue in its aqueous solution and removal of NO gas was also investigated.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Hydrothermal Synthesis of TiO2/SiO2 Composite Nanoparticles and Their Photocatalytic Performances

正典

啓介

道夫

et al. 2004

J. Ceram. Soc. Japan

View full text Add to dashboard Cite

Anatase (TiO 2 )/silica (SiO 2 ) composite nanoparticles over the compositional range of SiO 2 070.9 mol÷ were directly formed from acidic precursor solutions of TiOSO 4 and tetraethylorthosilicate by hydrolysis under mild hydrothermal conditions at 200 C. With increasing SiO 2 content, the specic surface area of the asprepared composite nanoparticles increased from 109 (SiO 2 0 mol÷) to 277 m 2 /g (SiO 2 70.9 mol÷), which was associated with an increase in the amorphous phase content. The composite nanoparticles with a unique microstructure, i.e., anatase crystallites 1416 nm in size that exist separately due to the presence of an amorphous silica phase in the TiO 2 /SiO 2 interface, showed enhanced photocatalytic activities for the decomposition of methylene blue (MB) in aqueous solution and better removal of NO gas in comparison with pure anatasetype TiO 2 . The highest photoactivity was obtained when the SiO 2 content in the composites was 25.1 mol÷ for MB decomposition and 48.2 mol÷ for NO oxidation.

show abstract

“…There have been many articles reporting the correlation of photocatalytic activity with the physical properties of TiO 2 powders, such as crystal structure [48,49], surface area [50], particle size [51], surface hydroxyls [52,53], etc.. It is believed by most of researchers in this field that the crystal structure, anatase, rutile, or brookite, is the most primitive and essential properties to predict the photocatalytic activity, e.g., anatase, but not rutile, crystallites have relatively high photocatalytic activity [54].…”

Section: Tio 2 -9 -mentioning

confidence: 99%

Photocatalytic Organic Syntheses: Selective Cyclization of Amino Acids in Aqueous Suspensions

2004

View full text Add to dashboard Cite

show abstract

Effect of surface hydroxyl density on photocatalytic oxygen generation in aqueous TiO2 suspensions

Cited by 93 publications

References 0 publications

Correlation between Some Physical Properties of Titanium Dioxide Particles and Their Photocatalytic Activity for Some Probe Reactions in Aqueous Systems

Correlation between Some Physical Properties of Titanium Dioxide Particles and Their Photocatalytic Activity for Some Probe Reactions in Aqueous Systems

Hydrothermal Synthesis of TiO2/SiO2 Composite Nanoparticles and Their Photocatalytic Performances

Photocatalytic Organic Syntheses: Selective Cyclization of Amino Acids in Aqueous Suspensions

Contact Info

Product

Resources

About