Heterogeneous photocatalysis in titania-stabilized perfluorocarbon-in-water emulsions: Urea photosynthesis and chloroform photodegradation

The photocatalytic behaviour of perfluorodecalin-in-water emulsions stabilized by bare and Cu-modified nanodispersed TiO2 has been studied using, as the model reactions, the simultaneous photoreduction of CO2 and NO3− to urea and the oxidative photodegradation of CHCl3. It has been shown that the employment of emulsified perfluorocarbons, capable of dissolving large quantities of gaseous substrates, as the carriers of TiO2 photocatalyst permits one to improve the selectivity of photoreduction and to enhance the urea photoproduction rate (by two to seven times depending on the nitrate concentration) due to high acting concentration of CO2 involved into light-induced reaction at the interface and possibility of stabilizing the reaction intermediates in the case of two-phase reaction medium. It has also been demonstrated that the ability of perfluorocarbons to dissolve both oxygen and organics leads to the enhancement of CHCl3 photodegradation in the TiO2-stabilized perfluorocarbon-in-water emulsion and allows for combining extraction with photocatalytic decontamination.