The incorporation of cerium and manganese ions in perfluorosulfonic acid (PFSA) membranes strongly decreases the fluoride ion emission rate from fuel cell membrane electrode assemblies through their scavenging of reactive oxygen species generated during fuel cell operation. Concentration gradients of these ions and water fluxes lead to their migration and even loss from the fuel cell, but little is known about these phenomena that nevertheless impact proton exchange membrane fuel cell durability. We have determined the diffusion behavior of manganese and cerium ions in perfluorosulfonic acid membranes and find the diffusion coefficient of divalent manganese ions to be higher than that of trivalent cerium. We relate this observation to their relative efficacy in mitigating membrane degradation in a proton exchange membrane single cell, where ionic HPLC analysis of effluent water, technique used here for the first time, shows that three times greater loss of manganese ions than cerium ions after 200 hours at open circuit. Fluoride emission from PFSA membranes degraded ex situ and in situ are corroborated by results from detailed infrared, 19 F MAS NMR and X-ray photoelectron spectroscopic analysis.

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Electrocatalysts of high mass activity, high electrochemical surface area, and long-term stability are required for the oxygen reduction reaction (ORR) at the cathode of fuel cells. Here, Pt-Y nanoalloys were produced by a solid-state approach on the most frequently used commercially available carbon supports, i.e., Vulcan XC-72, Ketjenblack EC-300J, and Ketjenblack EC-600JD. The prepared electrocatalysts were characterized and evaluated toward the ORR in acidic medium. Our results reveal that the nature of the carbon support influences the crystalline phase of the Pt-Y nanoalloy that forms on it as well as its particle size and near-surface chemistry. Using Ketjenblack EC-300 J produced mainly Pt3Y alloy nanoparticles of size ca. 5 nm. This carbon support effect was correlated to the activity/stability toward the ORR of the prepared nanoalloys. Our contribution provides insights for the optimal design of highly active/durable carbon-supported Pt-Y nanostructured electrocatalysts for fuel cells.

Fossil fuels are being progressively substituted by a cleaner and more environmentally friendly form of energy, where hydrogen fuel cells stand out. However, the implementation of a competitive hydrogen economy still presents several challenges related to economic costs, required infrastructures, and environmental performance. In this context, the objective of this work is to determine the environmental performance of the recovery of hydrogen from industrial waste gas streams to feed high-temperature proton exchange membrane fuel cells for stationary applications. The life-cycle assessment (LCA) analyzed alternative scenarios with different process configurations, considering as functional unit 1 kg of hydrogen produced, 1 kWh of energy obtained, and 1 kg of inlet flow. The results make the recovery of hydrogen from waste streams environmentally preferable over alternative processes like methane reforming or coal gasification. The production of the fuel cell device resulted in high contributions in the abiotic depletion potential and acidification potential, mainly due to the presence of platinum metal in the anode and cathode. The design and operation conditions that defined a more favorable scenario are the availability of a pressurized waste gas stream, the use of photovoltaic electricity, and the implementation of an energy recovery system for the residual methane stream.