Influence of Dye Content on the Conduction Band Edge of Titania in the Steam-treated Dye-dispersing Titania Electrodes

The titania and dye‐dispersing titania electrodes were prepared by a nitric acid‐catalyzed sol‐gel process. The dye‐dispersing titania contains the dye molecules dispersed on the surface of the individual nanosized titania particles. The photo‐cyclic voltammetry (Photo‐CV) and photoelectric measurements of the dye‐dispersing titania electrodes were conducted to clarify the factors changing the conduction band edge of the titania and the open‐circuit voltage (Voc) of the electrodes. The remaining nitrate ions caused a negative shift of conduction band edge of the titania of the dye‐dispersing titania. The conduction band edge of the titania was shifted in a negative direction in the electrode containing a greater amount of the dye. These results are due to the adsorption of nitrate ions and the dye‐titania complex formation on the titania particle surface. The effect of the dye‐titania complex formation on the shift in the titania conduction band edge was greater than that of the adsorption of nitrate ions due to strong interaction between the dye and titania through the carboxylate and quinone‐like groups of the dye. The shift in the titania conduction band edge corresponded to the change in the Voc value. The titania and dye‐dispersing titania electrodes were prepared by a nitric acid‐catalyzed sol‐gel process. The dye‐dispersing titania contains the dye molecules dispersed on the surface of the individual nanosized titania particles. The conduction band edge of the titania was shifted in a negative direction in the electrode containing a greater amount of the dye due to the dye‐titania complex formation on the titania particle surface. The effect of the dye‐titania complex formation on the shift in the titania conduction band edge was greater than that of the adsorption of nitrate ions due to strong interaction between the dye and titania.