Modification of photocatalyst surface reactivity for C2H2 oxidation after different plasma exposure

First, the time evolution of O atoms density in the gas phase during the post-discharge of a pulsed N₂-O₂ DC plasma is studied using a plasma induced fluorescence technique (PIF) where a main long pulse creates the plasma and a shorter one re-excites atoms in the time post-discharge. The surface loss coefficient of O atoms on pyrex, porous silica, porous TiO₂ is measured, this latter being a photocatalytic material. Second, adsorption/desorption kinetics of C₂H₂ molecules is monitored using infrared laser absorption spectroscopy after plasma treatment of these porous media. The respective role of ion bombardment, oxygen, nitrogen species as well as ultraviolet irradiation is studied by comparing N₂, O₂, air and argon plasma treatment.