Development of highly stable and mass transfer-enhanced cathode catalysts: Support-free electrospun intermetallic FePt nanotubes for polymer electrolyte membrane fuel cells

Abstract

Proton exchange membrane fuel cells (PEMFCs) are an alternative clean energy source and they are attracting increased attention. However, several limitations such as degradation of the carbon support and Nafion ionomer in the cathode electrode must be overcome for practical applications of PEMFCs. Support-free 1D-ordered intermetallic nanotubes (NTs) are considered as promising candidates for highly active and durable cathode catalysts in PEMFCs. However, 1D nanotubes are difficult to produce at large scale because they have generally been synthesized using a template-based method that requires multistep synthetic routes. Herein, a simple and scalable method to produce ordered-intermetallic FePt nanotubes by electrospinning is reported. When tested as cathode catalysts, under the US Department of Energy's reference condition, the activity of face-centered-tetragonal (fct) FePt NTs surpasses that of commercial Pt/C. In an accelerated degradation test at 1.4 V for 3 h, the degradation activity rate of fct-FePt NTs is only 10%, whereas that of commercial Pt/C catalysts is 65%. For practical PEMFCs, this approach would provide simple routes to support-free intermetallic nanotube structures with superior kinetic activity and higher durability than those of commercial Pt/C catalyst. Support-free intermetallic FePt nanotubes (fct-FePt NTs) are fabricated by a facile electrospinning process. Under US DOE reference test conditions, fct-FePt NTs show higher performance than commercial Pt/C; they also show excellent durability after an accelerated durability test at a potential of 1.4 V, at which carbon corrosion occurs. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim