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For efficient use of Pt catalyst in polymer electrolyte membrane fuel cells, the effects of cathode catalyst layer (CL) structure on the cell performance were evaluated by experiments and model analysis. CLs with various structures were fabricated and oxygen transport resistances of these CLs were measured from the limiting current densities with different total pressures. Using the experimental results and the model analysis, the contributions of resistance components for oxygen transport, in the CL pores, at the interface between gas and ionomer, and at the interface between ionomer and Pt surface, were evaluated individually. The parameters determining dominant resistances of oxygen transport such as the effective diffusion coefficient in the CL pores, the dissolution rate into ionomer, and the transfer rate at Pt surface, were also estimated. Furthermore, we discuss the method of reducing oxygen transport resistance in thin CL with low Pt loading.

Phenol-based oligomers linked with acetylenes at their meta positions, " meta"-ethynylphenol oligomers, were developed as a synthetic helical foldamer. The architecturally simple oligomers spontaneously formed helical higher-order structures by sequential intramolecular hydrogen bonds through the multiple phenolic hydroxy groups inside the cavities. The hydrogen bonds forced C-C≡C-C bond angles to largely bend toward the inside. Addition of chiral amines caused the helices to be chiral by electrostatic interactions between the resulting chiral ammonium cations and the phenolate anions.