The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 28, 1992
Filed:
Mar. 15, 1991
Earl J Taylor, Chelmsford, MA (US);
Gary A Moniz, Windham, NH (US);
Physical Sciences, Inc., Andover, MA (US);
Abstract
The disclosed electrocatalyst material is useful in electrodes, especially in cathodes for the reduction of oxygen or peroxide to water or hydroxide. The electrocatalyst typically comprises 0.1 to 20 weight-%, based on the weight of the material, of a supported particulate elemental gold wherein the particles are apparently crystalline in nature, apparently with exposed (100) faces, but smaller in size than 5 nanometers (<.ANG.). These tiny monocrystals of gold are supported on carbon black or particulate conductive ceramic-like compounds having a B.E.T. surface area of at least 50 m.sup.2 /g. The supported gold monocrystals appear to be selective for the reductions described above, and performance in air- or O.sub.2 -cathodes is outstanding, e.g. >0.7 volts vs. RHE at 200 mA/cm.sup.2, generally indicating a substantial proportion of four-electron change reactions when oxygen is being reduced. The electrodes (which are also useful as anodes in acid electrolytes) are made by impregnating the support material with a reducible gold compound dissolved in a polar solvent, gently evaporating the solvent, and chemically reducing the gold compound in situ at a moderate temperature with a flowing reducing gas (e.g. H.sub.2) then applying the resulting supported gold to a porous backing material. Typical gold content levels at the electrode surface are <2 mg/cm.sup.2. Cathodes of this invention are useful in various types of air or oxygen-depolarized cells, alkaline fuel cells, metal/air cells, metal/H.sub.2 O.sub.2 cells, oxygen sensors, electrochemical caustic concentrators, etc.