*2.1. Photooxidation of Primary Alcohols and Carboxylic Acids in Gaseous and Liquid Media*

The photocatalytic oxidation (PCO) of organic compounds to CO2 should be the ideal degradative process in depollution technologies, especially when solar light, which is a cheap, regenerable energy source, is used [6]. The photooxidation of alcohols is investigated as a model reaction for the abatement of organic pollutants [7]. The degradation of the intermediary carboxylic acids, which resulted in alcohol's photodegradation pathway, is also of great interest. In the meantime, alcohols can be an efficient and convenient hydrogen source via dehydrogenation or sacrificial reagents in photocatalytic water splitting.

Methanol is often chosen for fundamental studies concerning primary alcohols due to its structural simplicity but also as a prototype for organic pollutants in applicative research devoted to the environmental field. The oxidative sequence of methanol photomineralization to CO2 involving only a few organic intermediates is an appropriate choice for the investigation of oxidative degradation mechanism [8,9] but also for establishing the activity ranking of various photocatalysts. The numerous studies on methanol photooxidation, both in gaseous phase and liquid media, centered especially on titania [10], support the idea that the driving force over semiconductor-type materials is the capacity of the catalyst to photo generate appropriate density of charges (e−/h+) combined with prevention of charge recombination.
