Electrochemically assisted photocatalysis on anodic titania nanotubes

Research output: Contribution to journalArticle

Abstract

Heterogeneous photocatalysis is a clean technology where light energy is used to drive redox processes on the surface of semiconductors. Applications include the photoelectrolysis of water, organic synthesis, carbon dioxide fixation, ‘self-cleaning’ surfaces, and the treatment of polluted air and water. Titanium dioxide is the most suitable photocatalyst for water treatment applications because it is chemically and photochemically stable, non toxic, photoactive against a wide range of organic pollutants, inexpensive and readily available. The high photocatalytic activity is largely due to the wide band gap giving a large potential window to drive redox reactions, although this requires UV excitation. Nano-engineering of photocatalytic materials may improve the efficiency of the process. Self-organised, vertically aligned, titania nanotubes were grown by the electrochemical oxidation of titanium metal in the presence of fluorine ions. These materials were compared with compact oxide and nanoparticle (Degussa P25) electrodes for the photocatalytic and electrochemically assisted photocatalytic degradation of phenol and formic acid as model pollutants. It was found that ‘as-prepared’ nanotube films did not give any improvement in efficiency, however, following a post-growth anneal step to improve crystallinity, the nanotube films out-performed both the compact oxide and nano-particulate electrodes for the electrochemically assisted photocatalytic degradation of formic acid and phenol. The improvement in performance is due to the nanostructure providing a high surface area for reaction, aligned channels for mass transfer of reactants and products to and from the surface, efficient hole transfer to solution and good electron transfer to the contact electrode
Original languageEnglish
Pages (from-to)89-97
JournalCurrent Topics in Electrochemistry
Volume14
Publication statusPublished - 31 Jan 2009

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