| 摘要 |
Surfaces of porous and non-porous solid bodies generally non-metallic and non-conducting are coated with metal, said surfaces having reactive groups chemically and/or physically bound thereto and capable of forming a deposit of first-metal on said surface on contact with a solution of a metal salt; said first metal forming catalyst metal sites being capable of catalysing the reduction of a second metal salt in the presence of a reducing agent to form a thin continuous metal coating. The reactive groups consist of groups for reversible oxidation-reduction reactions contained in suitable organic compounds adsorbed on the solid surface. The first metal forming the catalyst metal sites is formed by treating the reactive surface with a salt of Ag, Au, Pt or Pd. Groups for reversible oxidation-reduction reactions may be formed chemically thereon, or adsorbed as with dyes and consist of, e.g. benzenoids. Suitable dyes for irreversible adsorption of oxidation-reduction units are the water-soluble redoxdyes. The preferred dyestuff is methylene blue. The second metal must have salts catalytically reduced by the first metal and is preferably Ag or Ni. For Ag the first metal may be Ag, Au, Pt or Pd but for Ni the first metal should be Au, Pt, Pd, but not Ag. Reducing agents used with a salt of silver as the second metal may be hydroquinone, hydroxylamine &c. For a salt of Ni as the second metal the reducing agent should be sodium or potassium hypophosphite used at 65 DEG C. Membranes coated by the method of the invention may be electroplated, using the metal-coated membrane as cathode, with, e.g., Cu, Pt, Au, Ir, Rh, Pd, Ni, Cr, Fe, Co and alloys thereof. The second metal coating, i.e. Ag, deposited can be replaced by another metal, e.g. Au, Pt or Pd, by chemical exchange or replacement as by contacting the Ag with an aqueous solution containing ions of such metal. Metal-coated membranes for fuel cell electrodes are 2-20 mils thick, preferably 2-12 mils, with metal coatings of 0.001-0.0001 inch thick. Substrates mentioned are membranes of inter polymers, carbon and glass. |
