We propose self-humidifying polymer electrolyte membranes (PEM) with highly dispersed nanometer-sized Pt and/or metal oxides for polymer electrolyte fuel cells (PEFCs) operated with dry H2 and O2. The Pt particles were expected to suppress the crossover by the catalytic recombination of H2 and O2, while the oxide particles false(TiO2false) that have hygroscopic property were expected to adsorb the water produced at Pt particles together with that produced at the cathode reaction and to release the water once the PEM needs water. The preparation protocol of TiO2 nanoparticles in a commercial Nafion 112 membrane via in situ sol-gel reactions was developed, resulting in a transparent membrane with uniform distribution of TiO2 in the PEM. Water adsorbability increased more than two times by dispersing only 2 wt % TiO2 in the PEM. That newly prepared TiO2 -PEM cooperated with highly dispersed Pt nanoparticles (Pt- TiO2 -PEM) was confirmed to perform a self-humidifying operation in a PEFC with dry H2 and O2. © 2002 The Electrochemical Society. All rights reserved.

The redox system composed of cysteine and persulfate ion , which initiates the aqueous polymerization of acrylamide, was investigated with using the pH-stat method, since the hydrogen ion was a product of the redox reaction. The polymerization rate orders for persulfate ion and acrylamide were 1.0 and 1.8, respectively. The rate order on cysteine changed from 0.5 to nil with an increase in the cysteine concentration. The generation rate of hydrogen ion was successfully obtained from the volume of sodium hydroxide solution used for neutralizing hydrogen ion generated during the polymerization in pH-stat apparatus. Hydrogen generation rate orders of sulfate ion, cysteine and acrylamide were 0.92, 1.00 and 0.61, respectively. It is elucidated that the redox initiation in a solution containing cysteine , persulfate ion and acrylamide is influenced by all components of this system .

No abstract