Platinum and platinum-based alloy nanotubes used as electrocatalysts for fuel cells

摘要

Electrocatalyst durability has been recently recognized as one of the most important issues that have to be addressed before the commercialization of the proton exchange membrane fuel cells (PEMFCs). The present invention is directed to a new class of cathode catalysts based on supportless platinum nanotubes (PtNTs) and platinum alloy nanotubes, for example, platinum-palladium nanotubes (PtPdNTs), that have remarkable durability and high catalytic activity. Due to their unique combination of dimensions at multiple length scales, the platinum nanotubes of the present invention can provide high platinum surface area due to their nanometer-sized wall thickness, and have the potential to eliminate or alleviate most of the degradation pathways of the commercial carbon supported platinum catalyst (Pt/C) and unsupported platinum-black (PtB) as a result of their micrometer-sized length. The platinum nanotube catalysts of the present invention asymptotically approach a maximum of about twenty percent platinum surface area loss in durability test, while the commercial PtB and Pt/C catalysts lose about fifty-one percent and ninety percent of their initial surface area, respectively. Moreover, the PtNT and PtPdNT catalysts of the present invention show higher mass activity and much higher specific activity than commercial Pt/C and PtB catalysts.