TiO2/WO3 hybrid structures produced through a sacrificial polymer layer technique for pollutant photo- and photoelectrooxidation under ultraviolet and visible light illumination
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TiO2/WO3 hybrid structures were produced on graphite substrates following a three step procedure: (i) electrochemical deposition of WO3 under potentiostatic conditions, (ii) electrochemical deposition of TiO2–polyaniline (PANI) composite layers by potentiostatic polymerization of aniline in the presence of TiO2 nanoparticles, (iii) high temperature (450 °C) treatment for decomposition of the PANI structure. Experiments on the photoelectrochemical response of the composite layers were carried out by cyclic voltammetry and chronoamperommetry in the dark and under illumination by using low power lamps emitting in the visible and UV spectrum ranges. The oxidation of three pollutants—oxalate ions, methanol and malachite green was used to evaluate the photoelectrocatalytic activity of the TiO2/WO3 structures. The photocurrents registered for the photooxidation of oxalate were higher than photocurrents measured at hybrid TiO2/WO3 electrodes obtained in conventional two-step electrodeposition of WO3 and subsequently TiO2 from corresponding salt solutions. The efficiency of the malachite green photodegradation in our experiments was also about two orders of magnitude higher than that obtained in TiO2/WO3 structures synthesized in a conventional way. These results are (very probably) due to the proposed synthetic approach involving PANI polymer layer as an immobilizing matrix and the opportunity to disperse homogeneously TiO2 nanoparticles on the WO3 surface provided.
KeywordsTitanium dioxide Tungsten trioxide Photoelectrocatalysis Methanol Oxalate ions Malachite green
The authors are thankful to Prof. N. Vuchkov for the measurements of the UV and VIS lamps spectra. The investigations are carried out within the working program of the project NATO SfP 982835.
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