Titanium dioxide is often used as a photoelectrode material for water splitting, but its band gap is too wide to achieve high conversion efficiencies in sunlight. Flame oxidation (pyrolysis) of titanium sheet has been suggested as a method to produce carbon doped TiO2 with a reduced band gap. In the present study, films were prepared using this and other thermal oxidation techniques and the photoelectrochemical water splitting efficiency of the resultant materials was examined using a xenon lamp. The oxide films were characterised physically, optically and electrochemically. Incident photon conversion efficiency measurements indicated no significant reduction in the band gap of films prepared using a hydrocarbon flame compared to rutile TiO2. Furthermore, these films -were found to have an efficiency comparable to that of films produced in a carbon free flame (hydrogen/oxygen). The results suggest that flame pyrolysis may not 'dope' TiO2 with carbon in the manner previously proposed. Any enhancement in photocatalytic efficiency resulting from the technique is likely to be due to the formation of non-stoichiometric TiO 2 or titanium sub-oxides.
|Journal||Developments in Chemical Engineering and Mineral Processing|
|Publication status||Published - 2006|