Comparative assessment of the efficiency of TiO2/OTE thin film electrodes fabricated by three deposition methods -: Photoelectrochemical degradation of the DBS anionic surfactant

This study reports on a comparative assessment of the efficiencies of TiO2/SnO2-doped OTE thin film electrodes fabricated by three different deposition methods. Process efficiencies, as measured by the kinetics of degradation, were examined by monitoring the photo-oxidative fate of two test substrates, namely the anionic surfactant sodium dodecylbenzenesulfonate (DBS) and the model compound sodium benzenesulfonate (BS). Methods chosen to fabricate the TiO2/OTE electrodes comprised (i) pulsed laser deposition, (ii) deposition of a TiO2 paste on the OTE plate, and (iii) sol-gel deposition. Both DBS and BS are readily photo-oxidized and, under our conditions, were partially mineralized to CO2 with the process being made particularly more efficient when the TiO2/OTE electrodes were anodically biased at +0.3 V, which generated a photocurrent during the photoelectrolysis. The sol-gel {C} and anatase {B1} electrodes proved especially useful under the +0.3 V bias. In the absence of any bias, however, DBS photodegraded faster on the TiO2-pasted electrode. Under otherwise similar conditions, the pulsed laser rutile TiO2/OTE electrode showed very little photoactivity. Some of the characteristics of the TiO2 film, such as the TiO2 crystalline form, film thickness, surface roughness, and film transparency appear to have some effect on the overall photodegradative process efficiency. (C) 2001 Elsevier Science B.V. All rights reserved.