CA1195378A

CA1195378A - Fuel cell cathode

Info

Publication number: CA1195378A
Application number: CA000431682A
Authority: CA
Inventors: Stanford R. Ovshinsky; Krishna Sapru; Srinivasan Venkatesan
Original assignee: Energy Conversion Devices Inc
Current assignee: Energy Conversion Devices Inc
Priority date: 1982-07-19
Filing date: 1983-06-30
Publication date: 1985-10-15
Also published as: EP0101421A3; JPS5958760A; EP0101421A2; US4430391A; AU564373B2; IN160085B; AU1644083A

Abstract

ABSTRACT .

A cathode for oxygen reduction in a fuel cell is formed from a host matrix including at least one transition metal element which is structurally modified by the incorporation of at least one modifier element to enhance its catalytic proper-ties. The catalytic body is based on a disordered non-equilibrium material designed to have a high density of catalytically active sites, resistance to poisoning and long operating life. Modifier elements, such as La, Al, K, Cs, Na, Li, C, and O
structurally modify the local chemical environ-ments of a host matrix including one or more transi-tion elements such as Mn, Co and Ni to form the catalytic materials of the cathode. The catalytic materials can be deposited as a layer on the sur-face of a porous electrode substrate to form a gas diffusion cathode or can be formed as a gas diffu-sion electrode.

Description

1~30 ~5371Eil The present invention relates generally to catalytic bodies and more speciEically to cata-lytic bodies for use as cathodes in an alkaline fuel cell. The catalytic body of the invention is based on a disordered non-equilibrium material designed to have a high density of catalytically active sites, resistance to poisoning and long operating life.

A fuel cell is an electrochemical device in which the chemical energy of a conventional fuel is converted directly and efficiently into low voltage electrical energy. Fuel cells have many potential applications such as supplying power for transportation vehicles, replacing steam turbines and remote power supply applications.
Fuel cells, lilce conventional batteries, operate by utilizing electrochemical reactions.
Unlike a battery, in which chemical energy is stored within the cell, fuel cells generally are supplied with reactants from outside the cellO
Barring failure of the electrodes, as long as the fuel, preferably hydrogen, and oxidant, typically oxygen, are supplied and the reaction products are removed, the cell continues to operate.
Fuel cells also offer a number of important advantages over engine or generator systemsO These /~

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include relatively high efficiency, environmental-ly clean operation especially when utilizing hy-drogen as a fuel, high reliability, few moving parts, and quiet operation. Fuel cells poten-tially are more efficient than other conventionalpower sources based upon the Carnot cycle. As the world's oil supplies become depleted, hydrogen supplies remain quite abundant and offer a viable alternate source of energyO Hydrogen can be pro-duced from coal or natural gas or can be produced without the use of fossil fuels, such as by the electrolysis of water using nuclear or solar energy.
The major components of a typical fuel cell are the anode for hydrogen oxidation and the cath-ode for oxygen reduction, both being positioned in a cell containing an electrolyte such as an alka-line electrolytic solution. Typically, the re-actants such as hydrogen and oxygen, are respec-tively fed through a porous anode and cathode and brought into surface contact with the electrolytic solution. The particular materials utilized for the cathode and anode are important since they must act as efficient catalysts for the reactions taking place.
In an alkaline fuel cell, the reaction at the anode is between the hydrogen fuel and hydroxyl ' ions (OH-) present in the electrolyte which react to form water and release electrons: H2 ~ 20H-

2~20 + 2e~. At the cathode, the oxygen, water, and electrons react in the presence of the cathode catalyst to reduce the oxygen and form hydroxyl ions (OH-): (2 + 2~20 + 4e~ -~ 40H~). The flow of electrons is utilized to provide electrical energy for a load externally connected to the anode and cathode.
Despite the above listed potential advan-tages, fuel cells have not been widely utilized.
Contributing to the fuel cell's lack of widescale commercial acceptance has been the relatively high cost of operating the fuel cells. The most im-portant factor contributing to the relatively high cost of producing energy from a fuel cell are the catalytic inefficiencies of the prior art cata-lytic materials used for the electrodes and/or the high costs of many of these materials. The cata-lytic inefficiencies of the materials add to the operating costs of the fuel cell since a lower electrical ener~y output for a given amount of fuel results. The use of expensi~e catalytic materials, such as noble metal catalysts, result i~ cells which are too expensi~e for widespread application~

5;37b~

The only alkaline fuel cells presently uti-lized are based upon noble metal catalysts and because of potential poisoning utilize ultrahigh purity fuels and electrolytes. These very expen-sive cells are only utilized for space applica-tions where cost is not a factor. Virtually no commercial a~plications presently utilize alkaline fuel cells.
For example, one prior art fuel cell cathode catalyst is platinum. Platinum, despite its good catalytic properties, is not very suitable for widescale commercial use as a catalyst for fuel cell cathodes, because of its very high cost.
Noble metal catalysts like platinum, also cannot withstand contamination by impurities normally contained in the hydrogen fuel and the electrolyte of the fuel cell. These impurities can include carbon mono~ide which may be present in hydrogen fuel or contaminants contained in the electrolyte such as the impurities normally contained in un-treated water including calcium, magnesium, iron, and copper.
The above contaminants can cause what is commonly referred to as a '^poisoning" effect.
Poisoning is where the catalytically active sites "~r.;
: O

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of the material become inactivated by poisonous species invariably contained in the fuel cell.
Once the catalytically active sites are inacti-vated, they are no longer available for acting as catalysts for efficient oxygen reduction reaction at the cathode. The catalytic efficiency of the cathode therefore is reduced since the overall number of available catalytically active sites is significantly lowered by poisoning. The decrease in catalytic activity results in increased over-voltage at the cathode and hence the cell is m~lch less efficient adding significantly to the operat-ing costs. Overvoltage is the voltage required to overcome the resistance to the passage of current at the surface of the cathode (charge transfer resistance). The overvoltage represents an un-desirable energy loss which adds to the operating costs of the fuel cell.
The reduction of the overvoltage at the cath-ode to lower operating cost of fuel cells has been the subject of much attention in the prior art.
More specifically, the attention has been directed at the reduction of overvoltage caused by the charge transfer resistance at the surface of the cathode due to catalytic inefficiencies of the particular cathode materials utilized.

37~3 One prior art attempt to improve on the noble metal based catalysts was to use a spinel NiCo2O4 material. The spinel material can be prepared as a powder by freeze drying and by co-precipitation from a solution of mixed salts. Application of the catalytic material to the electrode substrate can be accomplished by using a binder mixed with the catalysts or by dipping the electrode sub-strate into a solution of mixed nitrate salts which is then dried and heated to decompose the nitrates and cured.
The shortcomings of spinel catalysts, as well as other prior cathode catalysts proposed in the prior art, is that these catalysts are generally based upon a crystalline structure. In a crys-talline structure the catalytically active sites which provide the catalytlc effect of such mate-rials result primarily from accidently occurring, surface irregularities which interrupt the period-icity of the crystalline lattice. A few examplesof such surface irregularities are dislocation sites, crystal steps, surfac2 impurities and for-eign adsorbates. A major problem with a crystal-line structure is that the number of such ir-regularities forming the catalytically active

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sites are relatively few and occur only on thesurface of the crystalline lattice. This results in the catalytic material having a density of catalytically active sites which is relatively low. Thus, the catalytic efficiency of the mate-rial is substantially less than that which would be possible if a greater number of catalytically active sites were available for the oxygen reduc-tion reaction. Such catalytic inefficiencies result in a reduction in the fuel cell efficiency.
In summary, high catalytic efficiency from a relatively low cost material and resistance to poisoning in a fuel cell environment remain as desired results which must be attained before widescale commercial utilization of fuel cells is possible. Prior art fuel cell cathode catalysts, which have been generally predicated on either expensive noble metal catalysts or crystalline structures with a relatively low density of cata-lytically active sites, have not been able to meetthe above requirements.
We have found that the above disadvantages may be overcome with a fuel cell cathode including a multicomponent compositionally disordered cata-lytic material. The material includes a host : ~ .

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--8--matrix having at least one transition element and having incorporated therein one or more modifier elements. The modifier element modifies the local structural chemical environments of the material to provide the disorder. The material includes means creating an increased density of catalyti-cally active sites for the oxygen reduction reac-tion. The cathode may be incorporated in a fuel cell which includes a casing to position the cath-ode therein. The fuel cell also includes at leastone anode capable of hydrogen oxidation positioned within the casing and spaced from the cathode. An electrolyte is in contact with both the anode and the cathode.
The disadvantages of the prior art which have prevented the wide scale use of fuel cells are overcome by greatly improving and expanding in a unique and fundamental way the characteristics of the oxygen reduction electrode by utilizing dis-~0 ordered non-equilibrium multicomponent catalytic materials. The materials can be tailor-made to exhibit optimum catalytic activity for oxygen reduction by having a greater density of active sites, resistance to poisoning and long operating life.

5i3~
g The improved fuel cell cathodes are formed from non-equilibrium metastable highly disordered materials formed by modification techniques. The technique of modification to provide a non-equil-ibrium material having a high degree of disorderprovides unique bonding configurations, orbital overlap and hence a spectrum of catalytically active sites for the oxygen reduction reaction.
The modification technique involves tailoring of the local structural and chemical order of the materials of the present invention and is of great importance to achieve the desired characteristics.
Amorphous materials having only short range order can be utilized as can crystalline materials hav-ing long range order, but where the structure isdeliberately modified to increase the density of catalytically active sites above that obtainable in the prior art.
The improved catalytic activity of the pres-ent invention is accomplished by manipulating the local chemical order and hence the local struc-tural order by the incorporation of selected modi-fier elements into a selected host matrix to create the desired disordered material. The disordered multicomponent materials may be amorphous, poly-S3~

crystalline (but lacking long range order) or microcrystalline in structure, or an intimate mixture of amorphous and polycrystalline or micro-crystalline phases.
The components of these materials include a host matrix including at least one transition element, and at least one modifier element intro-duced into the host matrix in a non-equilibrium manner. The incorporation of the modifier element or elements in this manner provides the desired diOsordered structure of the material and creates numerous local structural and chemical environ-ments which act as catalytically active sites for the oxygen reduction reaction in a fuel cell. Co, Mn, and Ni are examples of transition elements particularly suitable for forming the host matrix and can also be utilized as modifier elements.
Examples of the preferred modifier elements in-clude La, Al, K, Li, Cs; Na, C, and O.
The catalytic materials of the present inven-tion can be utilized for gas diffusion fuel cell cathodes utilizing conventional techni~ues and also by applying a thin layer of the catalytic material onto a previously formed gas diffusion electrode substrate. Vacuum deposition tech-371~

niques, such as by cosputtering the host matrix and modifier elements, is a particularly suitable method of applying the catalytic materials for the gas diffusion cathodes.
The preferred embodiment of this invention will now be described by way of example.
The fuel cell of the present invention is based upon a unique approach to catalysis. This ` approach involves the design of non-equilibrium multicomponent disordered materials having tailor-made local structural chemical environments whichyield excellent catalytic characteristics. The cathodes are designed to have a high density of active sites, resistance to poisoning and long operating life to provide efficient low cost fuel cell operation. The manipulation of local struc-tural and chemical environments to provide cata-lytically active sites is made possible by uti-lization of a host matrix having at least one txansition element. ~he matrix can, in accordance with the present invention, be modified with atleast one other element to create a spectrum of bonding arrangements to provide a greatly in-creased density of catalytically active sites.
With a greater density of catalytically active i37~

sites, the oxygen reduction reaction occurs much more readily to allow a more efficient oxygen reduction reaction in the fuel cell and hence reduce operating costs.
The increased number of catalytically active sites not only increases catalytic activity, but enables the materials to be more resistant to poisoning. This is because with materials of the present invention a certain number of catalyti-cally active sites can be sacrificed to the ef-fects of poisonous species while a large number of unpoisoned sites still remain to provide the de-sired catalysis for oxygen reduction. Also, some of the poisons are inactivated by being bonded to other sites without effecting the active sites.
The disordered materials of the present in-vention, unlike the specific and rigid structure of crystalline materials, are ideally suited for manipulation since they are not constrained by the symmetry of a crystalline lattice or by stoichio-metry. By moving away from materials having re-strictive crystalline symmetry, it is possible, by selectively modifying in accordance with the pre~-ent invention, to accomplish a signiicant altera-tion of the local structural chemical environments involved in oxygen reduction to enhance the cata-lytic properties of the cathode materials. The disordered materials of the present invention can be modified in a substantially continuous range of varying percentages of modifier elements. This ahility allows the host matrix to be manipulated by the modifier elements to tailor-make or en-gineer materials with characteristics suitable for catalysis of the oxygen reduction reaction of a fuel cell. This is in contrast to crystalline materials which generally have a very limited range of stoichiometry available and thus a con-tinuous range of control of chemical and struc-tural modification of such crystalline materials is not possible.
In the disordered materials of the present invention, it is possible to attain unusual elec-tronic configurations resulting from nearest neigh-bor interactions between lone pairs, microvoids, dangling bonds, and unfilled or vacant orbitals.
These unusual electronic configurations can in-teract with the modifier elements of the present invention which are incorporated into the host matrix to readily modify the local structural chemical order and thus the electronic configura-aS37~

tions of the matrix to provide numerous catalyti-cally active sites for oxygen reduction in a fuel cell.
The disorder of the modified material can be of an atomic nature in the form of compositional or configurational disorder provided throughout the bulk of the material or in numerous regions of the materials. The disorder can also be intro-duced into the material by creating microscopic phases within the material which mimic the com-positional or configurational disorder at the atomic level by virtue of the relationship of one phase to another. For example, the disordered materials can be created by introducing micro-scopic regions of a different kind or kinds ofcrystalline phases, or introducing regions of an amorphous phase or phases in addition to regions of a crystalline phase or phases. The interfaces between these various phases can provide surfaces which are rich in local chemical environments providing numerous catalytically active sites.
A major advantage of the disordered materials of the present invention is that they can be tailor-made to provide a very high density and variety of catalytically active sites relative to materials ~L~''a53~gl3 based upon a crystalline structure. The types of structures which provide the local structural chemical environments for improved catalytic effi-ciency in accordance with the present invention include multicomponent polycrystalline materials lacking long range compositional order, micro-crystalline materials, amorphous materials having one or more phases, or multiphase materials con-taining both amorphous and crystalline phases or mixtures thereof.
As discussed later in greater det~il, modi-fication of the host matrix element or elements to form the catalytic materials of the present inven-tion can be accomplished by a variety of methods.
One type of formation involves vacuum deposition techniques, (i.e., sputtering, vapor deposition or plasma deposition). With these techniques the catalytically active material of the present in-vention can be directly applied to the electrode surface. In these methods, the host matrix ele-ment or elements are co-deposited along with the modifier element or elements to form a layer of catalytic material on the surface of a substrate or preformed porous gas diffusion electrode.
A number of materials were prepared by co-sputtering and thereafter tested to illustrate the 53~13 advantages of the disordered catalytic materials of the present invention. The materials referred to hereinafter were prepared and tested in general accordance with the following procedures except where indicated otherwise.
Cosputtering is a particularly suitable method for rapid screening or for forming the materials of the present invention. In forming the mate-rials by cosputtering, the host matrix element or elements is co-deposited along with the modifier element or elements to form a layer of catalytic material on the surface of a substrate or pre-formed porous gas diffusion electrode. The co-sputtering method enables the preparation of cata-lytic materials of the desired composition. Co-sputtering is also desirable because it facili-tates modification of the host matrix on an atomic scale, thus enabling tailor making of the material and also allowing for the formation of an intimate mixture of the material's component elements.

Thus, the host matrix and modifier elements can be deposited in a non-equilibrium metastable manner to tailor-make the desired type and degree of dis-ordered materials and create new local structural and chemical environments providing the desired ~537E~

catalytically active sites. Cosputtering alsoallows the application of a thin layer of cata-lytic material, such as l to 50 microns, which can be applied to a gas diffusion electrode used as a substrate, without affecting the gas diffusion operation of the porous substrate.
The catalytic layer may also initially in-clude leachable components like aluminum or zinc which are subsequently partially leached out to leave a layer of a higher surface to volume ratio which increases catalytic activity and further modifies the catalytic material. The leachable components also can be removed in sufficient vol-ume to ensure that the gas diffusion pores are not blocked when the materials are formed on gas dif-fusion electrodes used as a substrate.
The catalytic activity of the materials was first tested by codepositing the materials on any suitable conductive substrate, such as nickel or mild steel, prior to utili~ing the materials as gas diffusion electrodes. The substrates were sandblasted to remove surface oxides and to roughen the surfaces to provide better adhesion for the later applied catalytic layer. The substrate was then placed in a vacuum chamber of a Mathis R.F.

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sputtering unit chamber, or in some instances a Sloan Magnetron 1800 Sputtering unit. The chamber was evacuted to a background pressure of 1 x 10-6 torr. Argon gas was introduced into the chamber at a pressure of approximately 6.0 x 10-3 torr.
The Mathis sputtering target included a surface of sections of the elements desired to be included in the catalytic layer. The relative percentages of the elements contained in the deposited disordered materials were dependent upon the relative sizes of the sections of the target dedicated to the component elements and the positioning of the sub-strate relative to the target.
With the Sloan 1800 Magnetron sputtering unit, however, each element which was to be a component of the final catalytic layer had a sepa-rate target dedicated only to that element and the relative percentages of the component elements deposited in the catalytic layer were controlled by adjustment of the magnetic flux associated with each target as is well known by those skilled in this art. Regardless of whether the materials were produced utilizing the Mathis or Sloan Units, the substrate was maintained at a relatively low temperaturel for example 50C to 150C, to aid in the formation of the desired disordered structure.
The thickness of the catayltic layers deposited on the substrate were on the order of 1/2 to 50 mi-crons.
Some of the materials prepared had a com-ponent initially included therein and partially removed by leaching after formation of the co-sputtered layers. The leaching of -these materials was typically accomplished in a NaOH solution which was 17% by weight and at a temperature of 60C to 100C. The duration of leaching was typi-cally 1 to 4 hours.
Many of the materials were also subjected to a heat treatment at a temperature of in the ap-proximate range of 250C to ~00C preferably ap-proximately 350C in an oxygen or air atmosphere for approximately one-half hour. The chemical composition of the catalytic layer was determined by energy dispersive spec~roscopy or ~uger spec-troscopy. All chemical compositions stated in the following examples are given in atomic percent-ages.
The samples were tested in a half-cell uti-lizing an oxygen saturated 0.2 M ~aOH solution as the electrolyte at room temperature. In some ~53~3 instances gas diffusion cathodes were used with a layer of catalytic material sputtered thereon. In testing those materials the oxygen was supplied through the cathode as is customary in gas dif-fusion fuel cell cathodes.
The technique of cyclic voltammetry in an oxygen saturated solution was used for evaluation of catalytic activity. Such testing provides a fast screening technique for thin film electrodes deposited on planar substrates and is particularly useful when comparative performance analysis is desired. Two criteria were used to evaluate the performance of the electrodes. One criterion was the half-wave potential (E 1/2) which is the po-tential at which one-half the peak current is obtained. The second criterion was the net cur--rent density at a given potential. The net cur-rent density due to the catalytic material was determined by subtracting the value of the current density of the ca~hode when operated in a de-oxygenated solution from the current density value in an oxygen saturated solution. The current densities were calculated using the geometric sur-face area of the cathodes tested. For gas diffu-sion electrodes, the second crlteria, currentdensity was utilized to test the performance.

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TABLE I

Oxygen Reduction Results of Representative Screened Materials Formed by Cosputtering Material Composition Net Current Density E 1/2 By % At. Wt. uA/cm2 (~.25V) (V) Mng6.7C13.3 890 -.09 Mn7g.2Co2l.8 840 -.10 Mn77,sCol4,2Ni8.3 1500 -.105 Mn74~1C16~ oNi9 . ~ 1375 -.115 Mn64.sC21.2Nil4.4 1338 -.135 Some representative results of Mn host ma-trices modified with Co or Co and Ni are illus-trated in Table I. Mn alone tested under similar conditions was substantially worse than Ni or Co alone which are respectively, -.23V and 135 ~/cm2 and .35V and 200 ~A/cm2. Platinum references gave results of -.07 to -.08V and 2850 ~A/cm2 (-.llV). The modified Mn host materials were thus substantially better than any of the components alone and approached the results of platinum.
These materials are stable and do not degrade, while platinum de~rades very quickly unless uti-lized in an ultraclean environment.

t3S378 TABLE II

Oxygen Reduction Results of Representative Screened Materials Formed by Cosputtering Material Composition Net Current Density E 1/2 By % At Wt. ~/cm2 (-.25V) (V) Cogg.7A110.3 1350 -.11 Co77Lal4c5O4 1325 -.115 Co67.lLal3.6c3~9Ol5.4 1300 -.115 Cos4.gNi45.2 170 -.17 Some representative results of Co host ma-trices modified with various elements are illus~
trated in Table II. These materials also ex-hibited siynificantly better results than the individual components and approached those of platinum.
TABLE III

Oxygen Reduction Results of Representative Screened Materials Formed by Cosputtering Material Composition Net Current Density E 1/2 By ~ At. Wt. llA/cm2 (-.25V) _(V) Ni~s,gC20.7Mnl3.4 750 (-.15V) -.14 Ni5g.3Mn22.4Col9~3 1175 -.13 Nis2.6Co24.4Mn23.0 1200 -.135 Some representative results o Ni host ma-trices modified with Co and Mn are illustrated in Table III. These results are also significantly 7~

better than those of the constituent elements alone.
TABLE IV

Oxygen Reduction Results of Representative 5Materials Formed as Gas Diffusion Electrodes Material Composition Net Current Net Current Density Density By % At Wt. mA/cm2 ~20C) mA/cm2 (70C) -cO89,7~110.3 Cog7.3Mnl2.7 100 Co6l.3Ni3o.4Mn8~3 91 140 Coso.6Ni42.lMn7-3 76 co~4.~Mn33.6Ni2l.6 81 Mngs.3C10.2Ni4.5 129 15 Mn73ColgNig 80 Mn64,sC21.2Nil4.3 96 134 Catalytic materials were also formed by co-sputtering a thin layer of the material on the outer surface of a previously formed gas difusion electrode. In one group of gas diffusion elec-trodes the layer of catalytic material was formed through the reactive cosputtering of Mn, Co and Ni in an oxygen environment. The cathodes were oper-ated in the test cell by feeding oxygen gas from the back side of the cathode to the outer surface for oxygen reduction.

~L~''9537 Some representative results of the disordered materials utilized as gas diffusion electrodes are illustrated in Table IV. The electrodes were tested for current density, since it is well known that it is not practical to measure E 1/2. These results are significantly better than those of the platinum test electrodes which gave 54 to 64 mA/cm2 at -.25V~ The carbon based porous gas diffusion substrate gave 43 mA~cm2 by itself, but none of the test cathodes changed significantly with tem-perature. The modified materials showed signifi-cant increases in current density with an increase in temperature~
The modified materials showed excellent fuel cell catalytic characteristics, with good E 1/2 and current density values~ Other modifier ele-ments can be utillzed in a like manner as those described above and can include K, Cs, Na and Li.
Further, it should be noted that current density is related to surface area and can be manipulated by increasing the area and by controlling deposi-tion parameters. For example, two modified mate-rials were sputtered ~pon relatively porous graph-ite planar substrates resulting in very high cur-rent densities. (Mn47.2C29.4Ni23.4 and 3~1B

Mn68.4C18.3Nil3.3 with current densities of 9500 and 7250 ~/cm2, respectively.) While the present invention has been de-scribed in conjunction with specific embodirnents, those of normal skill in the art will appreciate that numerous modifications and variations can be made without departing from the scope of the pres-ent invention, and such modifications and varia-tions are envisioned to be within the scope of the appended claims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DE-FINED AS FOLLOWS:

1. A fuel cell cathode comprising:
a multicomponent compositionally disordered catalytic material including a host matrix having at least one transition element and having in-corporated therein one or more modifier elements, said modifier element modifying the local struc-tural chemical environments of said material to provide said disorder, said material including means creating an increased density of catalyti-cally active sites for the oxygen reduction re-action.

2. The cathode as defined in claim 1 wherein said means include a plurality of chemical ele-ments for providing a large number of catalyti-cally active sites.

3. The cathode as defined in claim 1 wherein said means include means designed to provide local chemical environments which include sites for selectively inactivating poisonous species.

4. The cathode as defined in claim 1 wherein said means include means for reducing oxygen at low overvoltages.

5. The cathode as defined in claim 1 wherein said disordered material includes a designed in-ternal porosity to enhance the oxygen reduction characteristics.

6. The cathode as defined in claim 1 wherein said means has non-equilibrium metastable phases and configurations.

7. The cathode as defined in claim 1 wherein said disordered material is a substantially poly-crystalline multicomponent material lacking long range compositional order.

8. The cathode as defined in claim 1 wherein said disordered material is a substantially micro-crystalline material.

9. The cathode as defined in claim 1 wherein said disordered material is a mixture of poly-crystalline or microcrystalline phase regions and amorphous phase regions.

10. The cathode as defined in claim 1 wherein said disordered material is an amorphous material containing at least one amorphous phase.

11. The cathode as defined in claim 1 wherein said disordered material is a mixture of micro-crystalline and polycrystalline phases.

12. The cathode as defined in claim 1 wherein said material is formed by cosputtering.

13. The cathode as defined in claim 1 wherein said means include a porous gas diffusion sub-strate and said material is deposited as a layer on said substrate.

14. The cathode as defined in claim 1 wherein said material is heat treated at a temperature in the range of approximately 250°C to 400°C.

15. The cathode as defined in claim 1 wherein said host matrix includes at least one element selected from the group consisting of Co, Mn and Ni.

16. The cathode as defined in claim 1 wherein said modifier element is a transition element.

17. The cathode as defined in claim 1 wherein said modifier element is selected from the group consisting of Co, Mn, Ni, La, C, K, Cs, Na, Li, O
and A1.

18. The cathode as defined in claim 1 wherein said catalytic material is heat treated in an oxygen containing atmosphere.

19. The cathode as defined in claim 1 wherein said modifier element is aluminum which is at least partially selectively removed from said material to further structurally modify said mate-rial, increase the catalytic activity of said material and form a porous material.

20. The cathode as defined in claim 1 wherein said means include means for increasing the cur-rent density at temperatures above ambient tem-perature.

21. The cathode as defined in claim 1 wherein said cathode is incorporated in a fuel cell, said fuel cell includes: a casing having said cathode positioned therein, at least one anode capable of hydrogen oxidation positioned within said casing and spaced from said cathode, and an electrolyte in contact with both said anode and said cathode.