How Selective Transport Layer Improves Efficiency and Durability of Proton Exchange Membrane Fuel Cells

In any electrochemical device, the separator or membrane allows specific ions to transport but blocks electrons and other chemical species, enabling the electrochemical energy to be harvested. However, small amounts of undesired species are known to permeate through the membrane, reducing overall system efficiency and lifetime. An emerging concept called the “Selective Transport Layer” preferentially allows only protons to pass through but reduces the permeance of other species by a meaningful degree. In this study, we demonstrate that a 60 nm thick graphene oxide composite layer can be very effective in reducing gas and ion permeation, even for a gas as small as H₂, while not noticeably increasing proton transport resistance. In electrode and membrane accelerated stability tests, we show that both electrode and membrane durability are improved by a factor of two. Microscopy and mathematic simulations confirm that the graphene oxide composite is effective in blocking transport of dissolved Pt²⁺. The improved durability and reduced H₂ fuel crossover are expected to substantially reduce initial and operating costs of the fuel cell system. How this technology may affect other membrane-based electrochemical devices is also discussed.