Photochemical reactions between photocatalysis

Zirconia also displays high activity in more complex surface photochemical reactions, for instance in the photolysis of water (Sayama and Arakawa, 1996) and the photoreaction between CO2 and H2 (Kohno et al, 2000). Although these and several other surface reactions on metal oxides (and metal halides) in heterogeneous photocatalysis have been claimed to be photocatalytic, no experimental evidence in support of their photocatalytic nature has ever been demonstrated. 

There are various interactions between photos and materials. Photocatalysis reaction is one of them. The catalytic reaction and photochemical reaction can be... 

Due to the fact that the difference between a sensitised and a catalysed photoreaction is somewhat arbitrary, due to the different and complex mechanisms involved (static and dynamic sensitisation, interaction with a photoproduct, photoinduced reactions,...), the term, photocatalysis has therefore been defined as broad as possible without the specific implication of any special mechanism, and refers then to the action of a substance whose function is activated by the absorption of a photon. A photocatalyst can be described as one involved in the quantum yield expression for a photochemical reaction without its stoichiometric involvement or more precisely, it appears in the quantum yield expression for reaction from a particular excited state to a power greater than its coefficient in the stoichiometric equation [14]. 

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