Unexplained transport resistances for low-loaded fuel-cell catalyst layers

For next-generation polymer-electrolyte fuel cells, material solutions are being sought to decrease the cost of the cell components, and, in particular, the amount of catalyst, without sacrificing performance and lifetime. However, as recently shown, this cannot be achieved in practice due most likely to limitations caused by the ionomer thin-film surrounding the catalyst sites, where confinement and substrate interactions dominate and result in increased mass-transport limitations. Mitigation of this issue is paramount to the future commercial viability of polymer-electrolyte fuel cells.