PREPARATION OF NEW SOLID POLYMER ELECTROLYTE COMPOSITES FOR WATER ELECTROLYSIS

A new simple procedure for the preparation of Solid Polymer Electrolytes (SPE)-electrocatalyst composites for water electrolysis-has been developed. In this new procedure (French patent, 1987), microparticles of noble metal electrocatalyst are precipitated simultaneously inside and outside near both surfaces of a perfluorinated ion-exchange membrane by chemical reduction of cationic precursor salts. The structure of the electrodes bonded onto the SPE has been investigated by scanning electron microprobe analysis and transmission electron microscopy. The effects of temperature and nature of anodic electrocatalyst on the cell voltage-current density relation are reported. Anodic overvoltage, cathodic overvoltage, ohmic drop within the SPE and roughness factor of the electrodes have been measured using an internal RHE reference electrode. The composites prepared according to this new procedure present low noble metal loadings (< 1 mg cm-2), low cell voltage (1.75 V at 1 A cm-2 and 80°C) and long time stability (over 15,000 h of continuous electrolysis). Partial results concerning the use of such composites for H2/O2 SPE fuel cell applications are also reported. © 1990.