Photoelectrocatalytic activity of bi-layer TiO2/WO3 coatings for the degradation of 4-chlorophenol: effect of morphology and catalyst loading

WO3 and bi-layer WO3/TiO2 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 WO3/SS and TiO2/WO3/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 TiO2 and WO3 was also established, ensuring the best performance of these photoelectrodes for the photooxidation of 4-CP under UV and visible light irradiation.