Photocatalysis


Photocatalysis

In chemistry, photocatalysis is the acceleration of a photoreaction in the presence of a catalyst. In catalysed photolysis, light is absorbed by an adsorbed substrate. In photogenerated catalysis the photocatalytic activity (PCA) depends on the ability of the catalyst to create electron–hole pairs, which generate free radicals (hydroxyl radicals: OH) able to undergo secondary reactions. Its comprehension has been made possible ever since the discovery of water electrolysis by means of the titanium dioxide.Commercial application of the process is called Advanced Oxidation Process(es) (AOP) [http://www.hfpurewater.com/Advanced_Oxidation.htm] . There are several methods of achieving AOP's, that can but do not necessarily involve TiO2 or even the use of UV. Generally the defining factor is the production and use of the hydroxyl ion.

Examples:
* Conversion of water to hydrogen gas by water splitting photocatalysis [1] . An efficient photocatalyst in the UV range is based on a Sodium tantalum oxide SodiumTantalumOxygen3 with cocatalyst nickel oxide. The surface of the Sodium tantalum oxide crystals is grooved with so called nanosteps that is a result of doping with Lanthanum (3-15 nm range, see nanotechnology). The NiO particles which facilitate hydrogen gas evolution are present on the edges, the oxygen gas evolves from the grooves.
* Use of titanium dioxide in self cleaning coatings. Free radicals [cite web |url=http://www.calutech.com/photocatalytic-oxidation.htm|title=Snapcat Photo Catalytic Oxidation with Titanium Dioxide (2005)|publisher=CaluTech UV Air|accessdate=2006-12-05] generated from TitaniumO2 oxidize organic matter. [http://www.titaniumart.com/photocatalysis-ti02.html]
* Disinfection of water by titanium dioxide photocatalysis [cite journal |author=McCullagh C, Robertson JMC, Bahnemann DW, Robertson PKJ |title=The application of TiO2 photocatalysis for disinfection of water contaminated with pathogenic micro-organisms: a review |journal=Research on Chemical Intermediates |volume=33 |issue=3-5 |pages=359-375 |year=2007 |doi=10.1163/156856707779238775] .
* Oxidation of organic contaminants using magnetic particles that are coated with titanium dioxide nanoparticles and agitated using a magnetic field while being exposed to UV light [2] .
* Use of photocatalysis in self-cleaning glass.

External source

* [1] Strategies for the Development of Visible-light-driven Photocatalysts for Water Splitting Akihiko Kudo, Hideki Kato1 and Issei Tsuji Chemistry Letters Vol. 33 (2004) , No. 12 p.1534

* [2] Kostedt, W. L., IV.; Drwiega, J; Mazyck, D. W.; Lee, S.-W.; Sigmund, W.; Wu, C.-Y.; Chadik, P. Magnetically agitated photocatalytic reactor for photocatalytic oxidation of aqueous phase organic pollutants. Environmental Science & Technology 2005, 39(20), 8052-8056.

References

External links

* [http://www.photokatalyse.fraunhofer.de/ Fraunhofer Photocatalysis Alliance]
* [http://www.photoenergy.org/ijp/glossary.pdf Glossary]
* [http://www.tip.csiro.au/IMP/EnergySustain/HydrogenProduction/materials.htm Materials]

ee also

*photolysis
*Photoelectrochemical cell


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  • photocatalysis — fotokatalizė statusas T sritis chemija apibrėžtis Cheminių reakcijų greitinimas vienu metu veikiant katalizatoriui ir šviesai. atitikmenys: angl. photocatalysis rus. фотокатализ …   Chemijos terminų aiškinamasis žodynas

  • photocatalysis — photocatalytic /foh toh kat l it ik/, adj. /foh toh keuh tal i sis/, n., pl. photocatalyses / seez /. Chem. the acceleration or retardation of the reaction rate in chemical reactions by light. [1910 15; PHOTO + CATALYSIS] * * * …   Universalium

  • photocatalysis — noun catalysis by a photocatalyst …   Wiktionary

  • photocatalysis — pho·to·ca·tal·y·sis .fōt ō kə tal ə səs n, pl y·ses .sēz the acceleration of a chemical reaction by radiant energy (as light) acting either directly or by exciting a substance that in turn catalyzes the main reaction compare PHOTOINACTIVATION (1) …   Medical dictionary

  • photocatalysis — pho·to·catalysis …   English syllables

  • photocatalysis — /foʊtoʊkəˈtæləsəs/ (say fohtohkuh taluhsuhs) noun Chemistry the acceleration of a photoreaction in the presence of a catalyst …   Australian English dictionary

  • photocatalysis — |fōd.(ˌ)ō+ noun Etymology: New Latin, from phot + catalysis : the acceleration of a chemical reaction by radiant energy (as light) acting either directly or by exciting a substance that in turn catalyzes the main reaction opposed to… …   Useful english dictionary

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