Thin film Pt/TiO2 catalysts for the polymer electrolyte fuel cell

Thin film Pt/TiO2 catalysts are evaluated in a polymer electrolyte electrochemical cell. Individual thin films of Pt and TiO2, and bilayers of them, were deposited directly on Nafion membranes by thermal evaporation with varying deposition order and thickness (Pt loadings of 3–6 μg cm−2). Structural and chemical characterization was performed by transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Oxygen reduction reaction (ORR) polarization plots show that the presence of a thin TiO2 layer between the platinum and the Nafion increases the performance compared to a Pt film deposited directly on Nafion. Based on the TEM analysis, we attribute this improvement to a better dispersion of Pt on TiO2 compared to on Nafion and in addition, substantial proton conduction through the thin TiO2 layer. It is also shown that deposition order and the film thickness affects the performance.