Abstract
Proton exchange membrane fuel cells are clean and efficient energy converters. Their accessible power ranges allow their use in the field of transport or stationary applications. Two main challenges concern the cathode deployment: i) The reduction of the amount of low abundant platinum group metal in the catalyst. ii) The enhancement of stability of the catalyst support at high voltage. In this work we present two strategies to address these challenges and improve performance and durability of the cathodes: developing novel ultra-low loaded platinum electrocatalysts and corrosion resistant support materials. To reduce noble metal amount in the catalyst, we developed platinum thin films, which allow maximal electrocatalytic exploitation thus minimal loading. For that, we have used electrochemical methods based on under-potential deposition and galvanic displacement. The thin structures deposited on model substrates were characterized by electrochemical, elemental analysis and microscopy techniques. To prepare corrosion resistant supports, our strategy was the replacement of conventional carbon black with a doped conducting tin oxide. SnO2-based materials have been demonstrated as electrochemical stable supports also promoting platinum activity for the oxygen reduction reaction. In this work, tantalum-doped tin oxide was prepared by electrospinning followed by calcination, leading to a fiber-in-tube morphology. This support was catalyzed with platinum nanoparticles prepared by a microwave-assisted polyol method, and characterized for their physico-chemical and electrocatalytic properties. In particular, stability to voltage cycling was evaluated by ex situ electrochemical analysis. The possibility to associate the extended surface electrocatalyst with the corrosion resistant supports to obtain active and durable cathodes is in progress.