Mesoporous Nb-Doped TiO2 as Pt Support for Counter Electrode in Dye-Sensitized Solar Cells

Mesoporous Nb-doped TiO 2 film was prepared by the sol−gel method on a transparent conducting FTO glass. Pt nanoparticles were impregnated in the mesoporous TiO 2 support substrate and tested for the counter electrode in dye-sensitized solar cells (DSSCs). The mesoporous Pt/Nb-doped TiO 2 was characterized by scanning electron microscopy and high-resolution transmission electron microscopy. The electrocatalytic activity of the Pt nanoparticles on different supports was studied by electrochemical impedance spectroscopy for the tri-iodide (I 3 − )/iodide (I − ) redox reaction in acetonitrile, a common electrolyte solution for DSSCs. By fabricating a Pt/Nb-doped TiO 2 electrode, the charge transfer resistance was reduced and the exchange current density was increased as the result of a larger active surface area of Pt in the mesoporous Nb-doped TiO 2 . This electrode could be used in other systems where there is a need to control the amount of Pt surface area and hamper Pt particle aggregation when operating at high temperatures. The impregnation of Pt in the mesoporous TiO 2 can also improve the mechanical rigidity and stability of the electrocatalyst against abrasion or generally mechanical contact, a desired property for practical applications.