An electrochemical recycling process of the noble metal such as Pt and Ru from the membrane electrode assemblies (MEAs) in fuel cells was investigated for the environment-friendly process without aqua regia. The dissolution rate of Pt in HCl solution was about 50 times as fast as those in H 2 SO 4 and HClO 4 solutions. The Pt dissolution rate increased linearly with HCl concentration. Pt dissolution under fluctuating potential using saw-tooth wave is 15 times faster than that under constant potentials. The electrochemical dissolution method can also be applied to the dissolution of Pt and Ru in the PtRu catalysts. The chemical methods using aqua regia, HCl-H 2 O 2 mixed solution, and HCl only were also investigated for the comparison as the electrochemical methods. The Pt dissolution rate decreased according to the order of aqua regia > 11.3 M HCl-0.36 M H 2 O 2 > 1 M HCl-10.3 M H 2 O 2 > 1 M HCl. The vaporization rate of oxidants (NOCl and Cl 2 ) from aqua regia at 333 K was 40 times as fast as that at 298 K by a spectrochemical method.

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The (ZrO2-1.6P2O5)-PTFE composite electrolytes have been prepared by mixing PTFE powders with different particle sizes and the shell-core-type ZrO2-1.6P2O5electrolyte, synthesized by solid state reaction with diammonium hydrogen phosphate, to improve the mechanical strength of the electrolyte. The H2gas permeability decreased and the cell performances improved with decreasing PTFE-particle size. The aging at 0.4 V above 443 K enhanced the ITFC performance owing to the penetration of the electrolyte to the carbon paper. The maximum output power enhanced by 63% after 15 h of aging at 573 K.

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