摘要： TiO2 is advantageous when used on the anode of a solar cell (SC) and achieves an electromotive force of 2 V when using another photocatalyst on the cathode (dual-photoelectrode fuel cell). However, both sufficient photocatalytic activity and electronic conductivity are required for the film, and these two requirements compete with each other. Herein, uniformly sized and shaped spheroidal, cubic, and “rhombic” TiO2 nanoparticles were synthesized, forming films using casting, slide, ball milling–slide (BS), and ball milling–mechanical (BD) methods. The AC/DC impedances of the films followed the order “rhombic”-ball milling–slide > “rhombic”-slide > cubic-slide > spheroidal-ball milling–mechanical > P25-casting ~ P25-slide ~ spheroidal-BS ~ spheroidal-slide ~ P25-ball milling–mechanical, demonstrating that “rhombic” and cubic TiO2 films were unsuitable for use on the SC photoanode. The reverse reaction rates of cathode reaction (water photo-oxidation), i.e., the 18O2 exchange reaction, were evaluated, which followed the order Cubic-TiO2 > Spher-TiO2 > Rhomb-TiO2 ~ P25-TiO2, demonstrating that the synthesized TiO2 was unsuitable for water oxidation. Polarizability and catalytic activity of TiO2 crystals were critical to maximize SC performance, and fluorescence peak intensity at 372–366 nm was well correlated to SC performance. P25-Slide on a photoanode at pH 1.78 and BiOCl-Cast on a photocathode at pH 2.00 enabled a maximum power of 85.2 μW cm?2 and an open-circuit voltage of 1.94 V.