Semiconductor heterogeneous photochemical

Bard AJ (1979) Photoelectrochemistry and heterogeneous photocatalysis at semiconductors. J Photochem 10 59-75... 

The net result of a photochemical redox reaction often gives very little information on the quantum yield of the primary electron transfer reaction since this is in many cases compensated by reverse electron transfer between the primary reaction products. This is equally so in homogeneous as well as in heterogeneous reactions. While the reverse process in homogeneous reactions can only by suppressed by consecutive irreversible chemical steps, one has a chance of preventing the reverse reaction in heterogeneous electron transfer processes by applying suitable electric fields. We shall see that this can best be done with semiconductor or insulator electrodes and that there it is possible to study photochemical primary processes with the help of such electrochemical techniques 5-G>7>. 

Since photoexcitation induces significant enhancement of the reactivity of electron transfer, photochemical reactions via photoinduced electron transfer have been explored in homogeneous systems [43 52], On the other hand, the term photocatalysis has usually been used in heterogeneous systems involving photoinduced electron transfer across the gas-solid or liquid-solid interface [53-60], Photocatalysis has been extensively studied using a semiconductor particle as a photocatalyst [53-60], Photocatalysis is initiated by the absorption of a band gap photon... 

Quite large enhancements in the rate of photochemical reaction have been observed in heterogeneous environments such as those that occur in aqueous micelle solutions or surface semiconductors (Cooper W.J. and Herr. F.L., I 987). The ways that micelles may influence solute chemical reactivity have been sumimarized below. These influences include cage, localization-compartmentalization, micro viscosity, polarity, pre-orientation, counterion and local electric field effects. 

Bard A J (1979), Photoelectrochemistry and heterogeneous photo-catalysis at semiconductors , / Photochem, 10,59-75. 

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