Résumé
One of the major issues concerning durability of PEMFC (Proton Exchange Membrane Fuel Cells) is the electrode degradation over time. Indeed, conventional electrocatalyst supports, based on carbon blacks, in fuel cell conditions suffer from corrosion leading to the aggregation, migration and detachment of the electrocatalyst nanoparticles with loss of performance. One strategy to overcome this issue is the replacement of carbon with more (electro)chemically stable supports. Recently, materials such as conducting oxides, nitrides and carbides have been shown promising applications as alternative supports. We are currently developing novel nanofibre and nanoparticle based PEMFC electrodes using non-conventional materials including niobium, tantalum and tungsten carbides, and doped titanium and tin oxides.
The challenges to be addressed are related to the development of nanofibres and nanoparticles having sufficient surface area to support and well disperse the electrocatalyst nanoparticles, while ensuring adequate electronic conductivity. We will review current progress in this area, and focus on morphology and physical-chemical properties of non-carbon supports prepared by electrospinning and hydrothermal methods, and the challenges of electrode development from them. Electrocatalytic activity of these systems will be addressed, in particular towards the oxygen reduction reaction, and the results of testing under accelerated ageing protocols will be described in order to compare their resistance to corrosion to that exhibited by conventional carbon based supports and assess their greater stability, and to underline the importance of a strong catalyst support interaction.