Charge transfer reductive doping of nanostructured TiO 2 thin films as a way to improve their photoelectrocatalytic performance

Electrochemistry Communications (Impact Factor: 4.29). 10/2006; 8:1713-1718. DOI: 10.1016/j.elecom.2006.08.006

ABSTRACT Nanostructured TiO 2 films can be reversibly doped by applying a potential of À0.6 V Ag/AgCl in aqueous 0.1 M HClO 4 for several min-utes. This charge transfer reductive doping causes significant changes of the cyclic voltammograms in the dark. Furthermore, an up to 6-fold increase of the efficiency for water photooxidation is observed upon electrochemical reductive doping. Both observations are explained by the build-up of a space charge layer through agglomerates of appropriately sized and shaped nanoparticles.

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    ABSTRACT: During the course of the present study, highly dense arrays of titanium oxide nanotubes (TON) were fabricated by anodization of titanium foil in aqueous fluoride solutions. The obtained TON arrays were then subjected to annealing and electrochemical treatment, followed by characterization using scanning electron microscopy, X-ray diffraction, cyclic voltammetry and electrochemical impedance (EI) techniques. By combining the effects of annealing and cathodic potential treatment, the cyclic voltammetry shows that the TON arrays catalyze the hydrogen evolution in acidic medium. This catalytic activity was not observed when the rutile phase started to form in TON arrays. EI results show that TON conductivity is substantially improved by cathodic potential treatment only when it contains the anatase phase. This was also confirmed by the cyclic voltammetric scan for the Fe(CN)63−/Fe(CN)64− couple, where a smaller peak separation between anodic and cathodic peaks was observed, rather than as-anodized TON.
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    ABSTRACT: Developing new nanophotocatalysts and identifying their roles are highly attractive in environmental protection and energy utilization. Photoelectro-Fenton process is an environmentally friendly technology and has a wide application in the control of environmental pollutants. However, efficient nanophotocatalysts responsive to visible light are still few. In this work, we have successfully synthesized a uniformly dispersed α-Fe2O3/TiO2 nanotubes hetero-nanostructure by electrochemical deposition method for the degradation of phenol. Compared with the separate α-Fe2O3 nanoparticles and TiO2 nanotubes, the composite α-Fe2O3/TiO2 nanotubes electrodes were more effective in the photoelectro-Fenton degradation of phenol and a 100% removal efficiency of phenol was obtained after 60 min treatment. The composite α-Fe2O3/TiO2 electrodes showed an enhanced absorbance in visible light region and had good stability to photoelectro-Fenton reactions. The role of α-Fe2O3 nanoparticles in various Fenton-related processes were systematically investigated. The results indicate that α-Fe2O3/TiO2 nanotubes are promising material for pollution prevention.
    Chemical Engineering Journal 05/2012; 191:356–363. · 4.06 Impact Factor


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May 26, 2014