Differences in the Electrochemical Performance of Pt-Based Catalysts Used for Polymer Electrolyte Membrane Fuel Cells in Liquid Half- and Full-Cells.

A substantial amount of research effort has been directed toward the development of Pt-based catalysts with higher performance and durability than conventional polycrystalline Pt nanoparticles to achieve high-power and innovative energy conversion systems. Currently, attention has been paid toward expanding the electrochemically active surface area (ECSA) of catalysts and increase their intrinsic activity in the oxygen reduction reaction (ORR). However, despite innumerable efforts having been carried out to explore this possibility, most of these achievements have focused on the rotating disk electrode (RDE) in half-cells, and relatively few results have been adaptable to membrane electrode assemblies (MEAs) in full-cells, which is the actual operating condition of fuel cells. Thus, it is uncertain whether these advanced catalysts can be used as a substitute in practical fuel cell applications, and an improvement in the catalytic performance in real-life fuel cells is still necessary. Therefore, from a more practical and industrial point of view, the goal of this review is to compare the ORR catalyst performance and durability in half- and full-cells, providing a differentiated approach to the durability concerns in half- and full-cells, and share new perspectives for strategic designs used to induce additional performance in full-cell devices.

Cross-Linked Sulfonated Poly(arylene ether sulfone) Containing a Flexible and Hydrophobic Bishydroxy Perfluoropolyether Cross-Linker for High-Performance Proton Exchange Membrane.

Here we show a simple and effective cross-linking method to prepare a high performance cross-linked sulfonated poly(arylene ether sulfone) (C-SPAES) membrane using bishydroxy perfluoropolyether (PFPE) as a cross-linker for fuel cell applications. The C-SPAES membrane shows much improved physicochemical stability due to the cross-linked structure and reasonably high proton conductivity compared to the non-cross-linked SPAES membrane due to the incorporation of flexible PFPE and the effective phase-separated morphology between the hydrocarbon and perfluorinated moieties forming well-connected networks. Under intermediate-temperature and low humidity conditions (90 °C, 50% RH, and 150 kPa), the membrane electrode assembly employing the C-SPAES membrane reveals an outstanding cell performance (1.17 W cm-2 at 0.65 V) ascribed to its reasonably high proton conductivity and enhanced interfacial compatibility between the perfluorinated moieties in the electrode and C-SPAES membrane. Furthermore, a hydration-dehydration cycling test result at 90 °C reveals that the C-SPAES membrane has notable durability against rigorous operating conditions.

High-performance Fuel Cell with Stretched Catalyst-Coated Membrane: One-step Formation of Cracked Electrode.

We have achieved performance enhancement of polymer electrolyte membrane fuel cell (PEMFC) though crack generation on its electrodes. It is the first attempt to enhance the performance of PEMFC by using cracks which are generally considered as defects. The pre-defined, cracked electrode was generated by stretching a catalyst-coated Nafion membrane. With the strain-stress property of the membrane that is unique in the aspect of plastic deformation, membrane electrolyte assembly (MEA) was successfully incorporated into the fuel cell. Cracked electrodes with the variation of strain were investigated and electrochemically evaluated. Remarkably, mechanical stretching of catalyst-coated Nafion membrane led to a decrease in membrane resistance and an improvement in mass transport, which resulted in enhanced device performance.

Knockdown of the interleukin-6 receptor alpha chain of dendritic cell vaccines enhances the therapeutic potential against IL-6 producing tumors.

Tumor microenvironment has emerged as one of the major obstacles against the clinical efficacy of dendritic cell (DC) vaccines. Tumor-derived IL-6 may inhibit the differentiation of hematopoietic progenitor cells into DCs and suppress DC maturation, rendering DCs tolerogenic. We hypothesized that silencing the IL-6 receptor alpha chain (IL-6Rα) would restore the functional competence of DC vaccines in mice with an IL-6-producing TC-1 tumor, and eventually give rise to protective immunity. We found that the IL-6Rα knockdown-DC vaccine significantly enhanced the frequency of tumor-specific CD8(+) CTLs-producing effector molecules such as IFN-γ, TNF-α, FasL, perforin, and granzyme B, and generated more CD8(+) memory T cells, leading to the substantially prolonged survival of TC-1 tumor-bearing mice.