AGING OF SINGLE-CRYSTAL TIO2 RUTILE ELECTRODES

The stability of TiO2 electrodes is studied by monitoring changes in the interfacial charge distribution through impedance measurements and photochemical current-potential (photo i-V) characterization. Aging effects caused by prolonged photoelectrolysis in acidic and alkaline media, or by anodic biasing in the dark are examined for reduced ([001] and [011] orientations) and substitutionally doped (niobium-doped [001]) TiO2. Three factors which lead to time- and “history-dependent” characteristics are: photocorrosion, slow ionization of deep donors, and field-aided diffusion. Prolonged photoelectrolysis in alkaline solutions results in undoping of the crystal and cleavage along crystallographic shear planes for the [001] orientation of reduced TiO2. © 1990, The Electrochemical Society, Inc. All rights reserved.