# US 5,702,836 A · Electrocatalyst

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- Number: US 5,702,836 A
- Document ID: US5702836A
- Status: Granted
- Kind: A
- Application number: 08/642,428
- Filed: 1996-05-03
- Granted: 1997-12-30
- Earliest claimed: 1996-05-03
- Assignees: University of Massachusetts
- Inventors: Chaoying Ma; Albert D. Kowalak
- Web page: https://patentgrep.com/patent/US5702836A

## CPC

- B01J 23/8906: {Iron and noble metals}
- H01M 4/921: {Alloys or mixtures with metallic elements}
- H01M 8/1009: with one of the reactants being liquid, solid or liquid-charged (H01M8/12 takes precedence)
- Y02E 60/50: Fuel cells
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A Pt/Fe/C electrocatalyst for, e.g., the oxidation of methanol in fuel cells, Pt/Fe colloidal particles and a method for preparing the Pt/Fe/C electrocatalyst are described.

## Claims

### Claim 1

A method for preparing an electrocatalyst, said method comprising
adding iron oxide to a first solution comprising platinum to produce a second solution comprising iron oxide and platinum; and
adding an oxidizing agent to the second solution and mixing the second solution under conditions and for a time sufficient to produce particles, each particle comprising an inner core of iron oxide and an outer shell of platinum oxide.

### Claim 2 (depends on 1)

The method of claim 1, wherein the second solution is mixed for a period of at least 18 hours.

### Claim 3 (depends on 1)

The method of claim 1, further comprising adding carbon black particles to the second solution to create Platinum/Iron/Carbon (Pt/Fe/C) particles.

### Claim 4 (depends on 1)

The method of claim 1, further comprising reducing a starting solution comprising H.sub.2 PtCl.sub.6 to produce the first solution, wherein the first solution then comprises platinum in the form of H.sub.3 Pt(SO.sub.3).sub.2 OH.

### Claim 5 (depends on 1)

The method of claim 1, wherein the oxidizing agent is hydrogen peroxide.

### Claim 6 (depends on 5)

The method of claim 5, wherein the hydrogen peroxide is added in the form of a solution that is 35 percent hydrogen peroxide by weight.

### Claim 7 (depends on 5)

The method of claim 5, wherein the first and second solutions' pH is maintained at a value of 4.5 to 5.5.

### Claim 8 (depends on 1)

The method of claim 1, further comprising adding a support for the particles.

### Claim 9

A method for preparing an electrocatalyst, said method comprising
reducing a starting solution comprising H.sub.2 PtCl.sub.6 to produce a first solution, wherein the first solution comprises platinum in the form of H.sub.3 Pt(SO.sub.3).sub.2 OH;
adding iron oxide to the first solution to produce a second solution comprising iron oxide and platinum;
adding an oxidizing agent to the second solution and mixing the second solution under conditions and for a time sufficient to produce particles, each particle comprising an inner core of iron oxide and an outer shell of platinum oxide;
adding carbon black particles to the second solution to create a paste comprising Pt/Fe/C particles and chloride compounds;
aggregating in the paste a supernatant comprising the Pt/Fe/C particles;
removing the supernatant from the paste;
dispersing the supernatant into a third solution;
testing the third solution for chloride; and
repeating aggregation, removal, dispersion, and testing of the supernatant until the testing shows a lack of chloride in the supernatant of Pt/Fe/C particles.

### Claim 10 (depends on 1)

The method of claim 1, wherein mixing the second solution occurs at room temperature and takes place over a period of time of at least 30 minutes.

### Claim 11 (depends on 1)

The method of claim 1, wherein mixing the second solution occurs at room temperature and takes place over a period of time of at least 24 hours.

### Claim 12 (depends on 9)

The method of claim 9, wherein the third solution comprises double-distilled deionized water and the supernatant is dispersed into the water using an ultrasonic bath.

### Claim 13 (depends on 1)

The method of claim 1, wherein the iron oxide is added in an amount that produces a platinum-to-iron-oxide mole ratio of approximately 0.5.

### Claim 14

An electrocatalyst comprising a plurality of bimetallic colloidal particles, each particle comprising an inner core of iron oxide and an outer shell of platinum oxide.

### Claim 15 (depends on 14)

The electrocatalyst of claim 14 further comprising a plurality of carbon particles.

### Claim 16 (depends on 14)

The electrocatalyst of claim 14, wherein each bimetallic particle is polyangular.

### Claim 17 (depends on 14)

The electrocatalyst of claim 14, wherein the diameter of each bimetallic particle is no less than 50 nm and no more than 90 nm.

### Claim 18 (depends on 15)

The electrocatalyst of claim 15, wherein the electrocatalyst has approximately 5 times the efficiency of a platinum/carbon-based electrocatalyst for direct methanol oxidation.

### Claim 19 (depends on 14)

A fuel cell comprising the electrocatalyst of claim 14.

### Claim 20 (depends on 15)

A fuel cell comprising the electrocatalyst of claim 15.

### Claim 21 (depends on 1)

A fuel cell comprising an electrocatalyst produced using the method of claim 1.

### Claim 22 (depends on 14)

A method of oxidizing an alcohol comprising contacting the electrocatalyst of claim 14 with the alcohol, and contacting the alcohol with a composition comprising oxygen.

### Claim 23 (depends on 22)

The method of claim 22, wherein the oxidizing occurs in a fuel cell for providing electrical current, the method further comprising
adding to the fuel cell the composition comprising oxygen;
adding an anode comprising the electrocatalyst, the anode oxidizing the alcohol to provide electrons; and
adding a cathode accepting electrons to reduce the composition comprising oxygen.