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TiO₂-based photoanodes were prepared via thermal oxidation of titanium foils in air at 500–900${}^{\circ }$C. Some of them were pre-treated via etching with HCl prior to oxidation, and others post-treated by means of sensitization with Ag₂S or CdS. XRD analysis revealed that the formation of rutile is observed even at 500${}^{\circ }$C. Etching prior to oxidation removes the Ti passivation layer and facilitates the oxidation process, and lowers the temperature at which the fundamental absorption edge is observed. The highest photocurrent values measured in a photoelectrochemical cell (PEC) were obtained for anodes etched prior to oxidation. Sensitization with CdS or Ag₂S increased photocurrent drastically. It was demonstrated that pre- and post-treated TiO₂-based photoanodes prepared in the process of thermal oxidation offer far better performance in PECs than those which had not been treated.

In this paper, novel chestnut-like TiO₂ was successfully synthesized by the hydrothermal method. The presence of chestnut-like structure not only increased the density of active sites with a high accessibility, but also facilitated the diffusion of solvent and products. Then, the chestnut-like TiO₂ based thin films on FTO were successfully prepared by the doctor-blade method. Moreover, the thickness of thin films can be adjusted via different repeated times. After that, in order to further improve its photoelectric properties, the adoption of CdS sensitization with different time interval via chemical bath route was studied. Photoelectrochemical (PEC) measurements showed that CdS/TiO₂ photoelectrode under the optimal condition exhibited minimal resistance and the fastest charge transfer rate. The highest photocurrent density can reach 35.1$\mu$A$\cdot$cm${}^{-2}$, which is almost 5-fold than that of pure chestnut-like TiO₂ (7.6$\mu$A$\cdot$cm${}^{-2}$) based thin films. The enhanced PEC properties could be ascribed to the improvement of light harvesting and the formation of heterostructure to accelerate the separation of photo-generated electron-hole pairs.