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

Mesoporous Nb-doped TiO2 film was prepared by the sol-gel method on a transparent conducting FTO glass. Pt nanoparticles were impregnated in the mesoporous TiO2 support substrate and tested for the counter electrode in dye-sensitized solar cells (DSSCs). The mesoporous Pt/Nb-doped TiO2 was characterized by scanning electron microscopy and high-resolution transmission electron microscopy. ne 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 TiO2 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 TiO2. 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 TiO2 can also improve the mechanical rigidity and stability of the electrocatalyst against abrasion or generally mechanical contact, a desired property for practical applications.