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Two types of titanate derivatives, layered hydrous titanium dioxide (H2Ti4O9·nH2O) and potassium octatitanate (K2Ti8O17) with a tunnellike structure, were synthesized using an ion‐exchange reaction. Fibrous potassium tetratitanate (K2Ti4O9·nH2O) was prepared by calcination of a mixture of K2CO3 and TiO2 with a molar ratio of 2.8 at 1050°C for 3 h, followed by boiling‐water treatment of the calcined products for 10 h. The material then was transformed to layered H2Ti4O9·nH2O through an exchange of K+ ions with H+ ions using HCl. K2Ti8O17 was formed by a thermal treatment of KHTi4O9·nH2O. Pure KHTi4O9·nH2O phase was effectively produced by a treatment of K2Ti4O9 with 0.005M HCl solution for 30 min. Thermal treatment at 250°–500°C for 3 h resulted in formation of only K2Ti8O17.

To investigate the scattering layer effect of a TiO 2 multilayer in dye-sensitized solar cells (DSSCs), we designed a new DSSC system, assembled with a CdS-TiO 2 scattering layer electrode. A high-magnification SEM image exhibited hollyhock-like particles with a width of 1.5-2.0 µm that were aggregated into 10-nm clumps in a hexagonal petal shape. The efficiency was higher in the DSSC assembled with a CdS-TiO 2 scattering layer than in the DSSC assembled with TiO 2 -only layers, due to the decreased resistance in electrochemical impedance spectroscopy (EIS). The short-circuit current density (J sc ) was increased by approximately 7.26% and the open-circuit voltage (V oc ) by 2.44% over the 1.0 wt % CdS-TiO 2 composite scattering layer and the incident photon-to-current conversion efficiency (IPCE) in the maximum peak was also enhanced by about 5.0%, compared to the DSSC assembled without the CdS-TiO 2 scattering layer.

TiO 2 fibers were formed by thermal treatment of layered H 2 Ti 4 O 9 (hydrous titanium dioxide) and KHTi 4 O 9 synthesized by ion-exchange reactions. The calcination of the former at 900°and 1050°C for 3 h yielded TiO 2 fibers with anatase and rutile phases, whose length and diameter were 15-20 and 2-5 m and 10 -15 and 3-5 m, respectively. The thermal treatment of the latter at temperatures of 250°to 500°C yielded pure K 2 Ti 8 O 17 , which tended to decompose to K 2 Ti 6 O 13 and TiO 2 at temperatures >600°C. At 1050°C, K 2 Ti 6 O 13 phase was formed with rutile TiO 2 fibers, whose length and diameter were 10 -20 and 1-3 m, respectively.