Probing the extent of [O2] depletion and [Cl−] production simultaneously at an illuminated TiO2 surface employing simple electrochemical methods

The extent of [O2] disappearance and Cl− production simultaneously from the UV-sensitised photodegradation of an aqueous aerated 4-chlorophenol (4-CP) solution at TiO2 surface have been investigated electrochemically, employing an oxygen sensor probe and a Ag/AgCl potentiometric detector electrode, respectively. The preceding mineralisation of 4-CP was monitored potentiometrically in terms of Cl− formation with illumination time while O2 electrode allowed the direct measurement of any change in [O2] at the illuminated TiO2 surface. A direct correlation was observed between the rates of O2 consumption and Cl− formation in the ongoing photo-process, which provided information that the photomineralisation process is ultimately an electrochemical process, in which the anodic (hole consumption) and cathodic (electron consumption) rate must balance.