关键词: 光电化学, TiO₂多孔膜电极, 氧化还原对

Abstract:

The photoinduced electron transfer process of the TiO2 porous film in the electrolytes containing different redox couples was investigated using photoelectrochemical techniques. The photocurrent action spectra, the potential dependence of photocurrent and the photocurrent transients indicate that the TiO2 porous film shows characteristics of semiconductor of n-type with an optical gap of 3.26eV.
After adding Fe（CN）63-／4- quinhydrone (BQ/HQ) in the electrolyte, the photocurrent action spectrum is similar to that without redox couple and the photocurrent tail in the visible region is due to the injection of electron of excited state of p-benzoquinone to the conduction band of TiO2 porous film.
After adding Fe（CN）63-／4- in the electrolyte, the photocurrent action spectrum is obviously different from that without redox couple. In addition to the photocurrent peak in the region of wavelength less that 380nm, a wide peak is observed in the visible region of 400-600nm which increases the efficiency of light-electric conversion. The photocurrent is anodic at the potential more negative than 0.2V, becomes cathodic at the potential of -0.2~0.3V and is anodic again but weak at potential more positive than 0.3V. At the potential more positive than -0.2V, a cathodic spike is observed on the photocurrent transients plot at the moment of light-on, and later transforms into anodic steady state photocurrent, which can be interpreted that the rapid injection of the photoinduced electron of the charge-transfer complex of [Fe（CN）64-]TiO2 in the conduction band of TiO2 porous film, and then reduces Fe（CN）63- in the electrolyte. 

Key words: Photoelectrochemistry, TiO₂ porous film electrode, Redox couple