Photoacoustic, photoelectrochemical current, and photoluminescence characterization of highly porous, polycrystalline TiO_2 electrodes

摘要

We report the effect of the application of a voltage in electrolyte on photoacoustic (PA), photoelectrochemical current (PEC), and photoluminescence (PL) spectra for the preparation of highly porous, polycrystalline TiO_2 electrodes. The intensities of the PA spectrum of the TiO_2 electrode with the voltage treatments are larger than these without the treatments below the band-gap region, suggesting the increase of the carrier concentration by the voltage treatments. The modulation frequency dependence of the PA intensity of the former is different from the latter in the low frequency region, indicating a reduction of interface states between the TiO_2 film and the substrate. The intensity of the PEC spectrum of the TiO_2 electrode with the voltage treatments is threefold that without the treatments above the band-gap region, suggesting good contact and the increase of carrier concentration. The PL intensity of the TiO_2 electrode with the voltage treatments is higher, suggesting the increase of radiative recombination center owing to the increase of donor levels formed by partially reduced Ti ions.