Catalysts photocatalytic activity

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. 

The Au/Ti02 catalyst shows activity for photocatalytic dehydrogenation of 2-propanol at 298 K. The activity of Au/Ti02 is attributed to its unique capability for producing photogenerated electrons evidenced by the featureless IR adsorption during UV-irradiation. 

Numerous data on the influence of adsorbed molecules on the photocatalytic activity of semiconductor catalysts in relation to the oxidation of water are evidence that acceptor molecules retard (65-68, 71-73, 77) and donor molecules speed up the reaction (65-68). 

The local structure around the lanthanide ions with differing redox potentials Eu(III)/(II) (-0.35 V vs. NHE), Yb(III)/(II) (-1.05 V), and Sm(III)/(II) (-1.55 V) in Ti02 particles was investigated by EXAFS. The photocatalytic reaction and EXAFS studies were also carried out for a calcined Yb(III) ion adsorbed-Ti02 catalyst [157], The photocatalytic activity of these lanthanides toward methyl blue photodecomposition was very similar, suggesting that adsorbed lanthanide ions on TiOz particles scarcely assist the high-photocatalytic activity of TiOz catalyst. However, the way in which the catalysts were activated was of high importance. The photocatalytic activity of the calcined Yb/TiOz... 

Heterogeneous photocatalysis is based on the photonie exeitation of a solid, which renders it more complex. The term photocatalysis may designate several phenomena that involve photons and catalyst, while this part of the ehapter will consider only semiconductor photocatalysis. Photocatalytic activity of Ti02 is based on its semiconductor properties. Radiation by photons, whieh have higher transfer energy, of such semiconductor leads to generation of electron-hole pairs [94] ... 

We focus attention here on titania (Ti02) for the following reasons. The first is that titania is a widely used oxide support for both metal particles and metal oxides, and used in some cases also directly as catalyst (Claus reaction, for example). The second is that it possesses multifunctional properties, such as Lewis and Bronsted sites, redox centres, etc. The third is that it has several applications both as a catalyst and an advanced material for coating, sensors, functional films, etc. The fourth is its high photocatalytic activity which make titania unique materials. 

As mentioned, the photocatalytic activation of Ti02 requires UV irradiation, and hence the semiconductor performance in the solar spectrum is inefficient. A solution to switch the photocatalytic activity to the visible spectral region was described by covalent attachment of an eosin dye monolayer to the semiconductor oxide particles of a Pd-Ti02 catalyst.168 The improved photocatalytic activities, specifically, the efficient formation of formate, are attributed to the effective injection of electrons from the excited dye into the semiconductor conduction band. 

It is worth noting that the photocatalytic activity of Pt/Ti02 for water photolysis is significantly enhanced when the catalyst is irradiated for a prolonged... 

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