Oxygen Reduction on Supported Platinum/Polythiophene Electrocatalysts

This work reports the use of polythiophene films as supporting matrix for Pt particles. The polymer film hosts were prepared using a strong acid aqueous solution, impregnated with Pt particles, and then tested for electrocatalytic properties for the oxygen reduction reaction (ORR). Cyclic voltammetry shows that the behavior of polythiophene in 12.5 M H ₂SO ₄ presents a general feature equivalent to that of several other conducting polymers, especially polypyrrole. Features of the UV-visible spectra obtained during the redox process are consistent with the polaron/bipolaron model. Scanning electron microscopy measurements show that a very homogeneous film layer is obtained with the Pt deposited as very line particles. Polarization measurements have shown that the ORR occurs through a mechanism involving four electrons with Tafel slopes of ca. 0.12 V dec ¹for potentials below 0.85 V vs. RHH (reference hydrogen electrode), in agreement with previous results for other types of dispersed Pt electrocatalysts.