Test results prove nickel carbide or nitride, nickel-cobalt carbide, titanium carbide or nitride, and intermetallic compounds of the transition or noble metals to be efficient electrocatalysts for oxygen reduction in alkaline electrolytes in low temperature fuel cells

Cattabriga, R. A.

Cohn, E. M.

Giner, J. D.

Makrides, A. C.

Swette, L. L.

English

NASA Technical Reports Server

NASA TECH BRIEF 
.
June 1970
	 Brief 70-10021 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage commercial 
application. Tech Briefs are available on a subscription basis from the Clearinghouse for Federal Scientific and Technical 
Information, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
Several New Catalysts for Reduction of Oxygen in Fuel Cells 
Three groups of compounds have been found to be 
efficient elect rocatalysts for the reduction of oxygen in 
alkaline electrolytes in low-temperature fuel cells: 
nickel carbide or nitride, or nickel-cobalt carbide; 
titanium nitride or carbide; and intermetallic com-
pounds of the transition or noble metals.. 
Nickel or Nickel-Cobalt Compounds: Carbides or 
nitrides of nickel, or nickel-cobalt carbidés, are good 
catalysts for 02 (air) cathodes for alkaline H 2-0 2 fuel 
cells.	 - 
Nickel nitride (Ni 3 N) was prepared by reaction of 
NH 3 with carbonyl nickel powder at 300°C; Ni3C 
and (Ni,Co)C, by decomposition of the acetates. The 
resultant powdered materials, bonded to nickel screens 
with a TFE fluorocarbon as the bonding and water-
proofing agent, were sintered for 5 min at 300° C. 
Electrode pieces measuring 1 cm 2 in surface area were 
tested as half-cells in a "floating electrode" cell which 
consists of a reaction chamber in which the test elec-
trodes are "floated" on the surface of a 35% aqueous 
solution of KOH at 75° C; 02 is passed over the back 
of the test electrode in the reaction chamber. 
The test electrode is driven potentiostatically against 
a large counter electrode; that is, by regulation of the 
potential between test electrode and a reference hydro-
gen electrode. The potential is swept slowly from 1000 
mV to about 500 mV and back to 1000 mV, while the 
current is measured between the floating electrode and 
the counter electrode. The derived current-potential 
curves show surprisingly high performance. Work is 
proceeding on optimization of the conditions of prep-
aration. 
Titanium Nitride or Carbide: These compounds 
also are efficient elect rocatalysts in low-temperature 
.	 H 2-02 fuel cells; in addition to reduction of 02, they
(continued overleaf) 
.
show resistance to corrosion in the potential regions 
of interest in alkaline electrolytes and serve as third- 
electrode oxygen-scavengers in alkaline batteries. 
The electrodes were tested as rotating-disk elec- 
trodes immersed in a 2M solution of KOH saturated 
with either N 2 or 02. By imposition of a linear poten- 
tial scan between the test electrode and a hydrogen 
reference electrode (by means of a slow linear potential 
signal to a potentiostat), the 1(E) or current-versus- 
potential curves were generated and recorded directly 
on an x-v plotter.	 - 
Before a test of activity the corrosion current was 
measured under gaseous N 2 at a series of potentials; 
it had to be measured with stirring so that it could be 
subtracted quantitatively from the oxygen-reduction 
current. After measurement of the corrosion current, 
the electrode was removed from the system and re- 
polished, and the solution was saturated with 02 for 
at least 45 mm. 
The repolished sample was introduced into the 
electrolyte at a potential of 1.23 V, and the 1(E) curve 
was initiated in the direction of decreasing potentials. 
At E = 0, the direction of the potential sweep was 
reversed. 
Transition and Noble Metals: Intermetallic com- 
pounds of the transition and noble metals (Pt, Pd, 
Au) are good alkaline-electrolyte catalysts for the 
elect ro-chemical reduction of 02 in low-temperature 
fuel cells; they include Ti 3 Au, TaPt 3 , TaPt2 , VPt3, 
CoPt 3 , NbPt 3 , Ti1r 3 , ZrAu 3 , and TaPd3. 
The compound Ti 3 Au is epecially advantageous 
because it contains no Pt and is almost 50% Ti by 
weight. Many of the intermetallics containing Pt show 
little or no loss of activity in 02 reduction due to 
dilution of the Pt, and Ti 3 Au shows strong indications 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Governmtht assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned.rights.
https://ntrs.nasa.gov/search.jsp?R=19700000021 2020-03-17T00:00:35+00:00Z
I	 I 
of being a better electrocatalyst than Pt. The surface 
composition of the catalyst may differ from the bulk 
composition. 
In fact, optimization of these catalysts for practical 
electrodes may require changes in the ratios of non-
noble metals—and especially so in Ti 3 Au in which 
the atomic ratio of 3:1 does not seem to be optimal. 
Notes: 
1. This information may interest designers or manu-
facturers of fuel cells or batteries, and power or 
gas companies. 
2. The following documentation may be obtained 
from:
Clearinghouse for Federal Scientific 
and Technical Information 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $0.65)
Reference: 
NASA-CR-97624 (N69-10585), Devel-
opment of Cathodic Electrocatalysts for 
Use in Low Temperature 1-12/02 Fuel 
Cells with an Alkaline Electrolyte 
Patent status: 
Inquiries about rights for commercial use of this 
invention may be made to NASA, Code GP, Wash-
ington, D.C. 20546. 
Source: E. M. Cohn of NASA, and

R. A. Cattabriga, J. D..Giner, 
A. C. Makrides, and L. L. Swette of

TYCO Laboratories, Inc.

under contract to

NASA Headquarters
(HQN- 10452-10453-10454)
is 
Brief 70-10021	 Category 01


Several new catalysts for reduction of oxygen in fuel cells

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