Fuel cells are foreseen to have an important role in sustainable energy systems, provided that catalysts with higher activity and stability are developed. In this study, highly active sputtered thin films of platinum alloyed with yttrium (Pt3Y) are deposited on commercial gas diffusion layers and their performance in a proton exchange membrane fuel cell is measured. After acid pretreatment, the alloy is found to have up to 2.5 times higher specific activity than pure platinum. The performance of Pt3Y is much higher than that of pure Pt, even if all of the alloying element was leached out from parts of the thin metal film on the porous support. This indicates that an even higher performance is expected if the structure of the Pt3Y catalyst or the support could be further improved. The results show that platinum alloyed with rare earth metals can be used as highly active cathode catalyst materials, and significantly reduce the amount of platinum needed, in real fuel cells.

Sufficient water transport through the membrane is necessary for a well-performing anion exchange membrane fuel cell (AEMFC). In this study, the water flux through a membrane electrode assembly (MEA), using a Tokuyama A201 membrane, is quantified using humidity sensors at the in- and outlet on both sides of the MEA. Experiments performed in humidified inert gas at both sides of the MEA or with liquid water at one side shows that the aggregation state of water has a large impact on the transport properties. The water fluxes are shown to be approximately three times larger for a membrane in contact with liquid water compared to vaporous. Further, the flux during fuel cell operation is investigated and shows that the transport rate of water in the membrane is affected by an applied current. The water vapor content increases on both the anode and cathode side of the AEMFC for all investigated current densities. Through modeling, an apparent water drag coefficient is determined to −0.64, indicating that the current-induced transport of water occurs in the opposite direction to the transport of hydroxide ions. These results implicate that flooding, on one or both electrodes, is a larger concern than dry-out in an AEMFC.

A deeper understanding of porous electrode preparation and performance losses is necessary to advance the anion exchange membrane fuel cell (AEMFC) technology. This study has investigated the performance losses at 50 °C for varied: Tokuyama AS-4 ionomer content in the catalyst layer, Pt/C loading and catalyst layer thickness at the anode and cathode, relative humidity, and anode catalyst. The prepared gas diffusion electrodes in the interval of ionomer-to-Pt/C weight ratio of 0.4–0.8 or 29–44 wt% ionomer content show the highest performance. Varying the loading and catalyst layer thickness simultaneously shows that both the cathode and the anode influence the cell performance. The effects of the two electrodes are shown to vary with current density and this is assumed to be due to non-uniform current distribution throughout the electrodes. Further, lowering the relative humidity at the anode and cathode separately shows small performance losses for both electrodes that could be related to lowered ionomer conductivity. Continued studies are needed to optimize, and understand limitations of, each of the two electrodes to obtain improved cell performance.

The performance and durability of 316L stainless steel bipolar plates (BPP) electroplated with Ni–Mo and Ni–Mo–P coatings are investigated in a proton exchange membrane fuel cell (PEMFC), using a commercial Pt/C Nafion membrane electrode assembly (MEA). The effect of the BPP coatings on the electrochemical performance up to 115 h is evaluated from polarization curves, cyclic voltammetry and electrochemical impedance spectroscopy together with interfacial contact resistance (ICR) measurements between the coatings and the gas diffusion layer. The results show that all the coatings decrease the ICR in comparison to that of uncoated 316L BPP. The Ni-Mo coated BPP shows a low and stable ICR and the smallest effects on MEA performance, including catalyst activity/usability, cathode double layer capacitance, and membrane and ionomer resistance build up with time. After electrochemical evaluation, the BPPs as well as the water effluents from the cell are examined by Scanning Electron Microscopy, Energy Dispersive and Inductively Coupled Plasma spectroscopies. No significant degradation of the coated surface or enhancement in metal release is observed. However, phosphorus addition to the coating does not show to improve its properties, as deterioration of the MEA and consequently fuel cell performance losses is observed.