Effect of rutile-type content on nanostructured anatase-type TiO2 electrode sensitized with CdSe quantum dots characterized with photoacoustic and photoelectrochemical current spectroscopies

Two types of nanostructured TiO2 electrodes were prepared without rutile-type (100% anatase-type) and with rutile-type (12%) content. CdSe quantum dots (QDs) were adsorbed onto each of the two types of TiO2 electrodes using a chemical deposition (CD) technique. Optical absorption and photoelectrochemical properties were characterized with photoacoustic (PA) and photoelectrochemical current (PEC) methods. The redshift of the PA and PEC spectra with increasing CdSe sizes were clearly observed, indicating quantum confinement effects and photosensitization. It was found that the PA and PEC spectra in the visible region were different for the two types of TiO2 electrodes for the same deposition time. The PA and PEC intensities of TiO2 electrodes with rutile-type content were larger than those without rutile-type content, indicating that adsorbed CdSe QDs in the TiO2 electrodes with rutile-type content might be higher than those without rutile-type content. Moreover, the transport properties in the TiO2 electrodes with rutile-type content might be improved. These results suggest that the rutile-type content is advantageous to increase the photoelectrochemical properties of TiO2 electrodes.