Reductions semiconductor photocatalyzed

Mineralization (meaning a complete oxidation) of numerous organic species cannot be regarded only as an oxidation process. In many cases oxidation must be preceded by reduction steps, eg photocatalyzed transformation of CC14 to C02 and Cl requires first reduction of carbon(IV) to lower oxidation states, followed by its reoxidation to C02 [30], In this context redox properties of an excited semiconductor play a crucial role. Photogenerated holes should support highly oxidative potential, but at the other surface sites an efficient reducer (electron) should also be available [64,65],... 

Reduction of carbon dioxide and its intermediates is catalyzed by illumination. Photocatalyzed reduction of CO2 to formaldehyde and methanol has been observed on semiconductor powders suspended in solution (25) as well as on GaAs electrodes (26). 

In analyzing the kinetic data of photocatalyzed oxidations (and reductions), mediated by photo-activated semiconductor particles, several studies have fitted the results to the simple rate expression of the form of eqn.l2 [25,37,38] ... 

Lichtin NN, Vijayakumar KM. (1983). Photocatalyzed Light-Driven Reduction of Co2 and N2 on Semiconductor Surfaces. JElectrochem Soc. 130, C108-C. 

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