http://www.eet.bme.hu/~plesz/Gyarmati%20Adam/the%20electrochemical%20oxide%20growht%20behaviour%20on%20titanium%20in%20acis%20and%20alkaline%20electrolytes.pdf

The electrochemical oxide growth behaviour on titanium in acid and alkaline electrolytes

The formation kinetics and electric properties of anodic barrier oxides on Al, Hf, Nb, Ta, Ti, and Zr depend on the migration of ions, controlled by an electric field strength of up to 107 V cm−1. The high field model, based on ideas of Guntherschulze, Betz, Verwey, Mott, and Cabrera, explains only parts of the experiments. Contradictory models and investigations of the last 60 years are compared with new results, which enable a more detailed understanding of many aspects of the high field model, e.g. the shape of experimental transients, the time and field dependent concentration of mobile ions, the nature of the mobile species and the interaction of anion and cation transport, and the location of the rate determining step.

Thin anodic oxide layers on aluminium and other valve metals: high field regime

Highly efficient semiconducting TiO2 photoelectrodes prepared by aerosol pyrolysis

Preliminary results are presented on the photochemical and photoelectrochemical degradation of aqueous organic solutions by anodic, thermal and sol–gel TiO2 films. The films were tested in a photochemical falling film reactor, and a photochemical/photoelectrochemical vortex reactor, and preliminary results are presented on the degradation of a range of model organics using these reactors. The former showed the best mass transport characteristics and most efficient light usage, whilst the latter reactor clearly showed the efficacy of the electric field enhancement effect. The results on the vortex reactor effectively represent a proof-of-concept of the electric field enhancement approach in large scale photoelectrochemical reactors. From time to time it is necessary to recoat the substrates, and the importance of the procedure adopted to remove ’old‘ TiO2 films prior to the fabrication of ‘new’ films is highlighted, as well as the mode of operation of the sol–gel films, and problems encountered in reactor design.

Applied studies on immobilized titanium dioxide films ascatalysts for the photoelectrochemical detoxification of water

Transient photocurrents at passive iron electrodes

Photocurrent spectroscopy has been used to examine the early stages of anodic film growth on titanium. Analysis of the photocurrent conversion efficiency as a function of wavelength for films formed at different potentials has shown that the film is essentially pure TiO2 above ca.1.5 V vs. SCE (at pH 0). Photocurrent spectroscopy has also been used to follow changes in the structure and thickness of the anodic film during breakdown at higher voltages.

Jerome F. McAleer

Papers

Photocurrent spectroscopy of anodic oxide films on titanium