# US 5,876,867 A · Platinum skeleton alloy-supported electrocatalyst, electrode using the electrocatalyst, and process for producing the electrocatalyst > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,876,867 A - Document ID: US5876867A - Status: Granted - Kind: A - Application number: 08/917,620 - Filed: 1997-08-26 - Granted: 1999-03-02 - Earliest claimed: 1996-08-26 - Assignees: N.E. Chemcat Corporation - Inventors: Takashi Itoh; Katsuaki Katoh; Tuyoshi Hashimoto - Web page: https://patentgrep.com/patent/US5876867A ## CPC - H01M 4/926: {on carbon or graphite} - B01J 23/56: Platinum group metals - B01J 23/89: combined with noble metals - H01M 4/921: {Alloys or mixtures with metallic elements} - H01M 2300/0008: Phosphoric acid-based - H01M 2300/0082: Organic polymers - Y02E 60/50: Fuel cells - H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY - B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract An electrocatalyst comprising an alloy of platinum with a base metal selected from the group consisting of gallium, vanadium, chromium, manganese, iron, cobalt, nickel and copper, having a structure of vacant lattice site type lattice defects; the alloy being supported on a conductive carbon powder. The electrocatalyst is useful as a platinum-supported catalyst for an electrode, and has a superior electrochemical oxygen reduction activity and has platinum alloy particles having less base metal component. ## Claims ### Claim 1 An electrocatalyst comprising an alloy of platinum with a base metal selected from the group consisting of gallium, vanadium, chromium, manganese, iron, cobalt, nickel and copper, having a structure of vacant lattice site defects, and a conductive carbon powder on which said alloy is supported. ### Claim 2 (depends on 1) The electrocatalyst according to claim 1, wherein the platinum is supported in an amount of 1% by weight to 60% by weight based on the whole catalyst. ### Claim 3 (depends on 1) The electrocatalyst according to claim 1, wherein the atomic ratio of platinum to the base metal in said platinum skeleton alloy is in the range of 1:1 to 1:0.05. ### Claim 4 (depends on 1) The electrocatalyst according to claim 1, wherein said conductive carbon powder has a BET specific surface area of from 50 to 1,500 m.sup.2 /g, a graphite (002) crystallite diameter of from 7 to 80 A, a graphite crystal interlattice distance d.sub.c (002) of from 3.40 to 3.79 A, and a DBP oil absorption of from 50 to 700 ml/100 gC. ### Claim 5 (depends on 1) The electrocatalyst according to claim 1, which is a cathode catalyst for a phosphoric acid fuel cell. ### Claim 6 (depends on 5) The electrocatalyst according to claim 5, wherein platinum is supported in an amount of 5 to 30% by weight based on the whole catalyst. ### Claim 7 (depends on 5) The electrocatalyst according to claim 5, wherein said conductive carbon powder is an at least partially graphitized carbon black having a BET specific surface area of from 50 to 180 m.sup.2 /g, a graphite (002) crystallite diameter of from 10 to 70 A. ### Claim 8 (depends on 1) The electrocatalyst according to claim 1, which is a cathode catalyst for a proton-exchange membrane fuel cell. ### Claim 9 (depends on 8) The electrocatalyst according to claim 8, wherein platinum is supported in an amount of 20 to 50% by weight based on the whole catalyst. ### Claim 10 (depends on 8) The electrocatalyst according to claim 8, wherein said conductive carbon powder has a BET specific surface area of from 120 to 1,500 m.sup.2 /g and a graphite (002) crystallite diameter of from 7 to 35 A. ### Claim 11 (depends on 1) An electrode comprising the electrocatalyst as claimed in claim 1 and a water-repellent binder which are bound to a conductive and gas-permeable support substrate. ### Claim 12 (depends on 11) The electrode according to claim 11, which is a cathode for a phosphoric acid fuel cell. ### Claim 13 (depends on 11) The electrode according to claim 11, which is a cathode for a proton-exchange membrane fuel cell. ### Claim 14 (depends on 1) A process for producing the electrocatalyst as claimed in claim 1, the process comprising; the first step of bringing a solid solution alloy of platinum with a base metal selected from the group consisting of gallium, vanadium, chromium, manganese, iron, cobalt, nickel and copper into support in a highly dispersed state with a conductive carbon powder; and the second step of removing the base metal at least in part from the crystal lattice of the alloy while retaining the crystal form to form a structure of vacant lattice site defects. ### Claim 15 (depends on 14) The process according to claim 14, wherein 20 to 90% by weight of the base metal contained in the platinum solid solution alloy is removed in the second step. ### Claim 16 (depends on 14) The process according to claim 14, wherein the second step comprises suspending a platinum solid solution alloy-supported carbon powder in phosphoric acid heated to 100.degree. C. to 200.degree. C. or in an aqueous mineral acid solution kept at a temperature of room temperature to 100.degree. C. in an atmosphere containing substantially no oxygen, and maintaining the resultant suspension with stirring for a certain time, followed by cooling, filtering, and washing with hot water until the filtrate has an electrical conductivity of 20 .mu.S/cm or less, and subsequently drying, whereby the base metal being removed.