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olo ine ype ele ec f h r t 79# ive oc 00 © Dowunder various electrochemical potentials without UV irradiation, and have found that a highly hydrophilic surface is obtained on the amorphous TiO2 electrode surface simply by cathodic polarization in the dark. Experimental Optically transparent conductive glass plates were used as sub-strates for the preparation of titanium dioxide electrodes. The sub-strates were partially dipped into titanium tetraisopropoxide solu-tion, leaving one-third of the area uncoated. The samples were sintered at 500 or 240°C for 30 min in air. To fabricate the TiO2 film electrode, a copper wire was attached to the conductive substrate remaining uncovered, with silver paste. After the silver contact dried, the copper lead wire was covered with an epoxy so that only the TiO2 surface was exposed. The crystallinity of the TiO2 elec-trodes was examined by X-ray diffraction ~XRD! ~RINT2100, Rigaku! at room temperature using Cu Ka radiation. The application of bias to the TiO2 electrodes and electrochemi-cal measurements were carried out in a standard three-electrode, single-compartment glass cell, fitted with a quartz window, with a potentiostat and an X-Y recorder coupled with a function generator.Highly Hydrophilic Surfac