Nobuo Eda

New Preparation Method for Polymer‐Electrolyte Fuel Cells

A new preparation method for the catalyst layer in the electrodes of a polymer electrolyte fuel cell, based on the process of preparing perfluorosulfonate‐ionomer (PFSI) colloid, was developed. In this method, both a good network of PFSI and uniformity of PFSIs on Pt particles were achieved with colloid formation of PFSI chains in the specific organic solvents. The applicable organic solvents had dielectric constants ranging from 3 to 10. The PFSI colloids were selectively adsorbed onto the carbon agglomerates with highly dispersed Pt particles on the surface, and a catalyst paste‐formation followed. Then the catalyst paste was spread over a carbon paper representing the gas diffusion layer, and two sheets of carbon paper with catalyst paste on them were hot pressed onto an ion‐exchange membrane from both sides. This simple preparation method provided high performance in fuel cells at low temperature (50°C).

Influences of Both Carbon Supports and Heat‐Treatment of Supported Catalyst on Electrochemical Oxidation of Methanol

The effects of carbon supports for platinum-ruthenium (Pt-Ru) catalysts on anode performance of direct methanol fuel cells (DMFC) were investigated. Good polarization characteristics of the methanol electrode were obtained for a Pt-Ru catalyst supported on an acetylene black with high specific surface area and a pore size distribution in the range of 3 to 8 nm. The performance of the methanol electrode increased with the increase in pore volume for the pore size distribution of 3 to 8 nm. Analyses of various carbon blacks and supported catalysts were carried out with several techniques: N{sub 2} adsorption (Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) methods), CO adsorption, transmission electron microscope, and scanning electron microscope observations. The effects of the heat-treating temperature, time, and atmosphere on the polarization curves of the methanol electrodes with the acetylene black were investigated. The heat-treatment in air at 370 C improved not only methanol oxidation but the durability of the Pt-Ru catalyst.