The effect of Nafion ionomer loading coated on gas diffusion electrodes with in-situ grown Pt nanowires and their durability in proton exchange membrane fuel cells

The effect of varying Nafion® ionomer loadings coated on the surface of gas diffusion electrodes (GDEs) with in-situ grown single crystal Pt nanowires and their durability in Proton Exchange Membrane Fuel Cells (PEMFCs) were investigated. GDEs were fabricated by growing Pt nanowires directly onto the Gas Diffusion Layer (GDL) surface with a simple one-step wet chemical approach at room temperature, as reported in our previous studies. The samples were then coated with various Nafion® ionomer loadings and tested as cathodes in a 25 cm2 PEMFC hardware with Hydrogen/Air. The data were compared to commercial GDEs (E-TEK ELAT® GDE LT 120E-W). Performance results showed that the as-prepared GDEs with Pt nanowires required higher Nafion® ionomer loading coating compared to the commercial ones. Accelerated ageing tests (500 cycles of voltage scan) were performed in views of evaluating the as-prepared GDE durability. The experimental data showed that the as-prepared GDEs exhibited much larger current densities at 0.7 V but higher degradation rates compared to commercial GDEs, indicating that the as-prepared GDEs gave poor durability. This was due to the difference in GDE surface nanostructures influenced by the electrolyte ionomer loading coating. This effect is further discussed in this paper.