2006-08-12 04:56:47 · 2 answers · asked by scutary2005 1 in Science & Mathematics ➔ Physics
It is speeding up a reaction by shining light on it.
2006-08-12 05:00:53 · answer #1 · answered by Benjamin N 4 · 0⤊ 0⤋
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 able to undergo secondary reactions.
Examples:-
* Conversion of water to hydrogen gas by water splitting photocatalysis 1. An efficient photocatalyst in the UV range is based on an tantalum oxide NaTaO3 with cocatalyst nickel oxide. The surface of the tantalum oxide crystals is grooved with so called nanosteps (3-15 nm range, see nanotechnology ). The NiO particles from which the hydrogen gas evolves are present on the edges, the oxygen gas evolves from the grooves.
* Use of titanium dioxide in self cleaning coatings. Free radicals generated from TiO2 oxidize organic matter
2006-08-12 12:08:28 · answer #2 · answered by Anonymous · 0⤊ 0⤋