Photoelectrochemical characterisation and photocatalytic activity of composite La2O3–TiO2 coatings on stainless steel

Composite La2O3–TiO2 and plain TiO2 photocatalytic coatings were prepared by a dip-coating technique on stainless steel substrates (SS) and tested as photoelectrodes in the electrically enhanced UV-photooxidation of organics. Electrode specimens were characterised by photovoltammetry under UV light in 0.1 M K2SO4 solutions in the absence and presence of oxalate (a model organic pollutant), while larger electrodes were used in bulk photooxidation of oxalate and malachite green (a typical dye). La2O3–TiO2/SS electrodes showed similar photocurrents to those of TiO2 coatings on Ti substrates (TiO2/Ti) and similar oxalate electro-photooxidation rates at moderate positive bias values. They also exhibited high removal rates for malachite green, but the electrochemical enhancement of its photooxidation was only observed at thin (0.5 mg cm−2) and low La2O3 content (5 mol% La) coatings.