| 摘要 |
1,162,385. Porous gas diffusion electrodes. VARTA A.G. 12 Sept., 1966 [18 Sept.,1965], No. 40699/66. Heading H1B. [Also in Division C7] Porous oxygen electrodes for fuel cells are made by etching in acid a metal powder such as Fe, Ni, Co or a metal-coated powder, coating the powder with Ag by deposition of Ag from a solution containing Ag ions and either sintering or hot pressing the coated powder or introducing the powder between porous layers, sieves, porous layers containing electrolyte or layers of solid electrolyte. Etching is effected in acetic, formic, oxalic or sulphuric acid. Glycol, formaldehyde, hydrazine or hydroborides may be added as reducing agents to the Ag solution which is maintained at a pH of 5À5-9 by adding hydroxyl ions. The Ag solution may also contain other catalysts such as Pd, Pt, Os, Ce and rare earths, Mn and Cu. The coated powder may be heated in H 2 at 180-600‹ C. and a pore former such as (NH 4 ) 2 CO 3 may be added. Three layer electrodes may be made by hot pressing the powder between cover layers of fine-pored Ni and coarse-pored Ni. |
