A stable and active iron catalyst supported on graphene nano-flakes for the oxygen reduction reaction in polymer electrolyte membrane fuel cells

Abstract

Two of the major challenges for the commercialization of automotive fuel cells are cost and durability. Cost estimations indicate that at a large production rate, the majority of the stack component cost comes from the catalyst ink. Decreasing this cost depends on finding a durable cost-effective platinum-free electrocatalyst. In this work, pure graphene nano-flake (GNFs) powders are produced by plasma decomposition. The GNFs are composed of 5–20 layers of stacked graphene sheets, a structure that appears to be closely associated to catalyst stability and durability. Additionally, the large number of attachment sites for nitrogen and atomic iron functionalization provide an avenue for improving activity. The GNFs were nitrogen functionalized and then used to support atomic iron to create the active sites for a non-noble catalyst. Iron was successfully incorporated at a value of 0.28at% on the surface of the catalyst structure. The catalyst was used on the cathode side of a polymer electrolyte membrane fuel cell (PEMFC) and showed stability over 100h. The performance of the catalyst demonstrates, to our knowledge, the first proof of a stable strictly iron-based fuel cell catalyst.