Next-Generation Polymer-Electrolyte-Membrane Fuel Cells Using Titanium Foam as Gas Diffusion Layer

In spite of their high conversion efficiency and no emission of greenhouse gases, polymer electrolyte membrane fuel cells (PEMFCs) suffer from prohibitively high cost and insufficient life-span of their core component system, the membrane electrode assembly (MEA). In this paper, we are proposing Ti foam as a promising alternative electrode material in the MEA. Indeed, it showed a current density of 462 mA cm^–2, being ca. 166% higher than that with the baseline Toray 060 gas diffusion layer (GDL) (278 mA cm^–2) with 200 ccm oxygen supply at 0.7 V, when used as the anode GDL, because of its unique three-dimensional strut structure promoting highly efficient catalytic reactions. Furthermore, it exhibits superior corrosion resistance with almost no thickness and weight changes in the accelerated corrosion test, as opposed to considerable reductions in the weight and thickness of the conventional GDL. We believe that this paper suggests profound implications in the commercialization of PEMFCs, because the metallic Ti foam provides a longer-term reliability and chemical stability, which can reduce the loss of Pt catalyst and, hence, the cost of PEMFCs

Bioinspired Synthesis of Melaninlike Nanoparticles for Highly N‑Doped Carbons Utilized as Enhanced CO₂ Adsorbents and Efficient Oxygen Reduction Catalysts

Highly N-doped nanoporous carbons have been of great interest as a high uptake CO₂ adsorbent and as an efficient metal-free oxygen reduction reaction (ORR) catalyst. Therefore, it is essential to produce porosity-tunable and highly N-doped carbons through cost-effective means. Herein, we introduce the bioinspired synthesis of a monodisperse and N-enriched melaninlike polymer (MP) resembling the sepia biopolymer (SP) from oceanic cuttlefish. These polymers were subsequently utilized for highly N-doped synthetic carbon (MC) and biomass carbon (SC) spheres. An adequate CO₂ activation process fine-tunes the ultramicroporosity (<1 nm) of N-doped MC and SC spheres, those with maximum ultramicroporosities of which show remarkable CO₂ adsorption capacities. In addition, N-doped MC and SC with ultrahigh surface areas of 2677 and 2506 m²/g, respectively, showed excellent ORR activities with a favored four electron reduction pathway, long-term durability, and better methanol tolerance, comparable to a commercial Pt-based catalyst

Facile Multiscale Patterning by Creep-Assisted Sequential Imprinting and Fuel Cell Application

The capability of fabricating multiscale structures with desired morphology and incorporating them into engineering applications is key to realizing technological breakthroughs by employing the benefits from both microscale and nanoscale morphology simultaneously. Here, we developed a facile patterning method to fabricate multiscale hierarchical structures by a novel approach called creep-assisted sequential imprinting. In this work, nanopatterning was first carried out by thermal imprint lithography above the glass transition temperature (<i>T</i>_g) of a polymer film, and then followed by creep-assisted imprinting with micropatterns based on the mechanical deformation of the polymer film under the relatively long-term exposure to mechanical stress at temperatures below the <i>T</i>_g of the polymer. The fabricated multiscale arrays exhibited excellent pattern uniformity over large areas. To demonstrate the usage of multiscale architectures, we incorporated the multiscale Nafion films into polymer electrolyte membrane fuel cell, and this device showed more than 10% higher performance than the conventional one. The enhancement was attributed to the decrease in mass transport resistance because of unique cone-shape morphology by creep-recovery effects and the increase in interfacial surface area between Nafion film and electrocatalyst layer