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The photoelectrocatalytic performance of thermal and particulate TiO 2 films on Ti electrode substrates has been studied by photovoltammetry and bulk photoelectrolysis. The thermal TiO 2 film electrodes were prepared by Ti annealing in air at 700°C and 500°C while the particulate electrodes were prepared from dispersions of Degussa P-25 TiO 2 deposited onto Ti substrates and subsequently sintered at 700°C and 500°C. The photocurrent in the absence and presence of the model organic species of oxalate as well as its photooxidation rate depends on coating surface area, type (thermal or particulate) and crystallographic form (anatase or rutile). A method is proposed to account for surface area variations by normalising the data with respect to the electroactive surface area of the TiO 2 electrodes, as estimated by their surface electrochemistry in the dark. The thermal electrodes show high photocurrents both in the absence and the presence of oxalate whereas the performance of particulate electrodes is significantly improved upon oxalate addition. Nevertheless, the efficiency of thermal 700°C TiO 2 for oxalate photooxidation during bulk photoelectrolysis is comparable to that of Degussa P-25 TiO 2 -coated electrodes.

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WO 3 and bi-layer WO 3 /TiO 2 coatings of different catalyst loadings were electrosynthesized on stainless steel 304 (SS) substrates from acidic aqueous solutions by single-step and consecutive steps potentiostatic cathodic deposition. The resulting WO 3 /SS and TiO 2 /WO 3 /SS photoelectrodes were screened for their photoresponse under ultraviolet (UV) and visible light illumination by photovoltammetry and photoamperometry in sulphate solutions, in the absence and presence of 4-chlorophenol (4-CP). They were also evaluated for bulk photo-oxidation of 4-CP under constant potential, in the voltage range determined on the basis of the photovoltammetric tests. The optimal weight ratio between TiO 2 and WO 3 was also established, ensuring the best performance of these photoelectrodes for the photooxidation of 4-CP under UV and visible light irradiation.

Bi-layer WO