Porous clusters of silver powder promoted by zirconium oxide for use as a catalyst in gas diffusion electrodes, and method for the production thereof

A method of producing a nano-size silver catalyst promoted by zirconium oxide, the method comprising:

• providing a silver powder containing porous clusters of silver particles;
• impregnating said clusters of silver particles by contacting said particles with an aqueous solution containing a zirconium (IV) compound selected from the group consisting of zirconium (IV) dinitrate oxide hydrate and zirconium (IV) dichloride oxide hydrate, so as to form a suspension;
• contacting said suspension with an aqueous alkaline solution to produce zirconium hydroxide, which precipitates in pores of said porous clusters;
• rinsing and drying the clusters with said zirconium hydroxide precipitated in said pores to produce a dried residual material;
• and
• heating said dried residual material to effect dehydration and subsequently heating to produce crystals of zirconium oxide, thereby forming the nano-size silver catalyst promoted by zirconium oxide.

An air electrode comprising:

• a catalyst having a plurality of porous clusters of silver particles, each cluster of said clusters including a plurality of primary particles of silver and crystalline particles of zirconium oxide (ZrO2), wherein at least a portion of said crystalline particles of ZrO2 is located in pores formed by a surface of said plurality of primary particles;
• a water-repellant polymer;
• a current collector;
• and
• a porous hydrophobic film, wherein the catalyst, said water-repellant polymer and said current collector are located on a single broad face of said porous hydrophobic film.

An electrochemical cell comprising:

• an anode;
• a cathode having a current collector, a water-repellant polymer, a porous hydrophobic film and a catalyst, the catalyst having a plurality of porous clusters of silver particles, each cluster of said clusters including a plurality of primary particles of silver and crystalline particles of zirconium oxide (ZrO2), wherein at least a portion of said crystalline particles of ZrO2 is located in pores formed by a surface of said plurality of primary particles and wherein the catalyst, the water repellent polymer and said current collector are located on a single broad face of said porous hydrophobic film;
• and
• an electrolyte.