Buckypaper-based catalytic electrodes for improving platinum utilization and PEMFC's performance

Platinum (Pt) catalytic electrode was developed by using carbon nanotube films (buckypaper) as supporting medium and electrodeposition method to deposit Pt catalyst. Buckypapers are free-standing thin films consisting of single-walled carbon nanotubes (SWNTs), multi-walled carbon nanotubes (MWNTs) and/or carbon nanofibers (CNFs) held together by van der Waals forces without any chemical binders. Special mixed buckypapers was developed by layered microstructures with a dense and high-conducting SWNT networks at the surface, as well as large porous structures of CNF networks as back supports. This unique microstructure can lead to improve Pt catalyst accessibility and mass exchange properties. Pt particles of about 6 nm were uniformly deposited in porous buckypapers. A promising electrochemical surface area of ∼40 m²/g was obtained from these electrodes. A Pt utilization as low as 0.28 g_Pt/kW was achieved for the cathode electrode at 80 °C. Pt utilization efficiency can be further improved by optimization of the electrodeposition condition in order to reduce the Pt particle size.