Ultra-low catalyst loading cathode electrode for anion-exchange membrane fuel cells

A new cathode architecture for anion-exchange membrane fuel cells (AEMFCs) is proposed and fabricated by direct deposition of palladium (Pd) particles onto the surface of the micro-porous layer (MPL) that is interfaced with a backing layer. The MPL is composed of carbon nanotubes while the backing layer is made of a carbon paper. The sputter-deposited electrode with a worm-like shape not only extends the electrochemical active surface area, but also facilitates the oxygen transport. This new cathode, albeit with a Pd loading as low as 0.035 mg cm⁻², enables the peak power density of an AEM direct ethanol fuel cell to be as high as 88 mW cm⁻² (at 60 °C), which is even higher than that using a conventional cathode with a 15-times higher Pd loading. The significance of the present work lies in the fact that the new sputter-deposited electrode is more suitable for fuel-electrolyte-fed fuel cells than the conventional electrode designed for proton-exchange membrane fuel cells (PEMFCs).