Photocatalytic reactivity

The photocatalytic reactivity for TCE decomposition was increased by platinization and the photocatalytic activity of the catalysts prepared with leached solution fi-om wasted automobile catalyst was similar to that of the catalysts modified with H2PtCl6. 

Park, H., Neppolian, B., Jie, H.S., Ahn,J.-P., Park, J.-K., Anpo, M. and Lee,D.-K. (2007) Preparation of bimetal incorporated Ti02 photocatalytic nanopowders by flame method and their photocatalytic reactivity for the degradation of diluted 2-propanol. Current Applied Physics, 7, 118-123. 

CONTROL OF PHOTOCATALYTIC REACTIVITY IN PHOTO-OXYGENATION REACTION... 

However, the photocatalytic reactivity of aromatics, especially benzene, is lower than some of the more promising pollutants for this emerging technology. Also, at aromatic concentrations of as little as 10 ppm, photocatalysts may exhibit apparent deactivation. Here, we summarize achievements to date and discuss methods for increasing aromatic reactivity, minimizing photocatalyst deactivation, and periodically regenerating used protocatalysts. 

Such high photocatalytic reactivities of photo-formed e and h can be expected to induce various catalytic reactions to remove toxic compounds and can actually be applied for the reduction or elimination of polluted compounds in air such as NO cigarette smoke, as well as volatile compounds arising from various construction materials, oxidizing them into CO2. In water, such toxins as chloroalkenes, specifically trichloroethylene and tetrachloroethene, as well as dioxins can be completely degraded into CO2 and H2O. Such highly photocatalyti-... 

Figure 6 UV-vis absorption spectra (diffuse reflectance) of the original undoped pure TiO2 (a) and TiO, chemically doped with Cr ions (b -e ). Cr ions chemically doped in 10" mol/g (a) undoped original pure TiOi (P-25), (b ) 16, (c ) 200, (d i 1000, (e ) 2000. The TiO2 photocatalysts chemically doped with Cr ions did not exhibit any photocatalytic reactivity.

Figure 7 Reaction-time profiles of the photocatalytic decomposition of NO on the Cr-ion-implanted TiO2 photocatalyst under visible-light (X> 450 nm) irradiation at 295 K. The unimplanted original pure TiO2 photocatalyst did not show any photocatalytic reactivity under the same reaction conditions.

It is important to emphasize that the photocatalytic reactivity of the metal ion-implanted titanium oxides under UV light (X < 380 nm) retained the same photocatalytic efficiency as the unimplanted original pure titanium oxides under the same UV light irradiation conditions. When metal ions were chemically doped into the titanium oxide photocatalyst, the photocatalytic efficiency decreased dramatically under UV irradiation due to the effective recombination of the photo-formed electrons and holes through the impurity energy levels formed by the doped metal ions within the band gap of the photocatalyst (in the case of Fig. 6)... 

Figure 8 Effect of the Cr- and V-ion-implantation on the photocatalytic reactivity of TiO2 under outdoor solar beam irradiation for the photocatalytic decomposition of NO at 295 K (solar beam 38.5 mW/cm i.

Figure 10 Effect of the depth profile of V ions in the V-ion-implanted titanium oxide photocatalyst on their photocatalytic reactivity for the decomposition of NOx under visible light (X > 450 nm) irradiation at 295 K.

Kitano, M., Takeuchi, M., Matsuoka, M., Thomas, J. M. and Anpo, M. (2005). Preparation of visible light-responsive Ti02 thin film photocatalysts by an RF magnetron sputtering deposition method and their photocatalytic reactivity. Chem. Lett. 34(4), 616-617. 

The initial rate of the photocatalytic hydrogenolysis reaction on the anchored titanium oxide was determined to be about 88 nmol (h g of catalyst), whereas with the bulk rulUe powder catalyst the value was about 13 nmol (h-g of catalyst). The concentration of the effective TP or O species in the anchored catalyst was only 3.2 x 10 mol/(g of catalyst), whereas for bulk TiOi it was 1.25 x 10 mol/(g of catalyst) (168). As a result, the photocatalytic reactivity of the anchored titanium oxide can be considered to be higher than that of bulk Ti02 catalyst by about two or three orders, of magnitude. 

As shown in Fig. 46, the photocatalytic reactivity of the coppcr(I) ion species anchored within ZSM-5 increases with the evacuation temperature, passing through a maximum at 1173 K. Figure 46 also shows that the yields of the photoluminescence, i.e., the photoluminescence yield attributed to the coppcr(I) species, change in a similar manner. Such a good parallel between the yields of the photoluminescencc and the yields of the photocatalytic decomposition of NO clearly indicates that the excited state of the isolated copper(I) species plays a decisive role in the decomposition of NO into N2 and O2 under UV irradiation of the catalyst at 275 K (172-180). 

UV irradiation of the titanium-siheon binary oxide catalyst in 1-octanol acetonitrile solutions in the presence of O2 led to the oxidation of 1-octanol to produce 1-octanal as the main product, whereas no products were detected under dark conditions. The specific photocatalytic reactivities of the titanium oxide moieties in the bindar oxides can be determined since the... 

Fig. 3. The effects of the Ti/Si composition of Ti/Si binary oxides on their photoluminescence yields and specific photocatalytic reactivities for the photocatalytic reduction of CO2 with H2O to produce CH4 and CH3OH at 328 K.

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