KR20090082457A - Electrocatalyst layers for fuel cells and methods of making electrocatalyst layers for fuel cells - Google Patents

Abstract

An electrochemical fuel cell is disclosed. The electrochemical fuel cell comprises a membrane electrode assembly comprising: an anode having an anode gas diffusion layer and an anode electrocatalyst layer; a cathode having a cathode gas diffusion layer and a cathode electrocatalyst layer; and a proton exchange membrane disposed between the anode and the cathode. At least one of the anode electrocatalyst layer and the cathode electrocatalyst layers comprises an electrocatalyst and polyfurfuryl alcohol. The polyfurfuryl alcohol may be distributed uniformly or non-uniformly within the electrocatalyst layer. Methods of making the electrocatalyst layer having an electrocatalyst and polyfurfuryl alcohol are also disclosed.

Description

Electrocatalyst layers for fuel cells and methods of making electrocatalyst layers for fuel cells

The present application is directed to US 35 U.S.C. Claims benefit of U.S. Provisional Application No. 60 / 864,877, filed November 8, 2006, under 119 (e), which is incorporated herein by reference in its entirety.

The present invention relates generally to electrocatalyst layers for electrochemical fuel cells and methods of making electrocatalyst layers for electrochemical fuel cells.

Electrochemical fuel cells convert reactants, ie, fuel and oxidant fluid streams, to generate power and reaction products. Electrochemical fuel cells generally use a membrane electrode assembly (MEA) placed between two isolation plates through which the reactant fluid stream can substantially permeate. The plates typically act as current collectors and support the membrane electrode assembly (MEA). The plates may also have reactant channels formed therein and act as flow field plates to provide access of the reactant fluid stream, such as hydrogen gas and air, to the membrane electrode assembly (MEA) and The reaction product formed during operation is removed. Typically, multiple fuel cells are electrically coupled in series to form a fuel cell stack.

One type of electrochemical fuel cell is a polymer electrolyte membrane (PEM) fuel cell using a membrane electrode assembly (MEA) that includes a solid polymer electrolyte or an ion exchange membrane. The membrane acts as a barrier to space the reactant streams from each other and also as an electrical insulator between the two electrodes. Typical commercial polymer electrolyte membranes (PEMs) are E.I. Sulfonated perfluorocarbon membrane sold by DuPont de Nemours and Company under the designation Nafion®.

The membrane electrode assembly (MEA) further comprises two electrodes each disposed on opposite sides of the ion exchange membrane. Each electrode typically comprises a porous electrically conductive substrate, such as carbon cloth or carbon fiber paper, which acts as a gas diffusion layer and structurally supports the membrane. Typically, the gas diffusion layer also accepts a substrate of carbon particles with an optional binder as well. The electrodes can be provided on a suitable electrocatalyst support (i.e. fine platinum particles supported on a carbon black support) and are typically a gas diffusion layer and membrane that is an accurate metal composition (i.e. platinum metal black or alloy thereof). It further comprises an electrocatalyst between. Electrocatalysts can also accept ionomers to improve quantum conductivity through the electrodes.

The electrode can typically contain a hydrophobic material such as polytetrafluoroethylene (PTFE) that imparts water management properties to the electrode. Water management is a key characteristic of the electrode because water is produced during operation of the fuel cell. Without proper water removal, the resulting water may accumulate, leading to performance losses due to increased mass transport losses, especially at large current densities where relatively large amounts of water are produced.

However, since polytetrafluoroethylene (PTFE) is not homogeneously mixed with hydrophobic and hydrophilic ionomers, the use of polytetrafluoroethylene (PTFE) has been limited when used in electrocatalyst compositions comprising ionomers. In addition, "flowing" polytetrafluoroethylene (PTFE) into the fluid diffusion layer requires a high sintering temperature and / or damages the electrocatalyst or destroys most of the ionomers.

Thus, although progress has been made in the art, there is a need for an electrocatalyst layer with improved water management properties. The present invention addresses this need and provides more related advantages.

Briefly described, the present invention generally relates to an electrocatalyst layer, an electrochemical fuel cell, and a method for producing an electrocatalyst layer for an electrochemical fuel cell.

In one embodiment, the membrane electrode assembly comprises: an anode comprising an anode gas diffusion layer and an anode electrocatalyst layer; A cathode comprising a cathode gas diffusion layer and a cathode electrocatalyst layer; And a proton exchange membrane disposed between the anode and the cathode, wherein at least one of the anode electrocatalyst layer and the cathode electrocatalyst layer comprises polyfurfuryl alcohol. In some embodiments, the cathode electrocatalyst layer comprises a platinum alloy catalyst and an ionomer. In another embodiment, the distribution of polyperferyl alcohol is heterogeneous.

In another embodiment, a method of making an electrode for an electrochemical fuel cell includes applying an electrocatalyst composition to a sheet material; Adding a monomer perferyl alcohol to the electrocatalyst composition; And polymerizing the monomer perferyl alcohol after adding the monomer perferyl alcohol and applying the catalyst composition.

These and other aspects of the invention will become apparent upon reference to the following detailed description and the accompanying drawings.

In the drawings, like reference numerals identify similar elements or operations. The size and relative position of the elements in the figures need not be to scale. For example, the shapes and angles of the various elements have not been scaled, and some of the elements have been arbitrarily enlarged and arranged to improve the understanding of the drawings. Moreover, the special forms of the elements shown are not intended to convey any information about the actual form of the particular elements and have been selected solely for ease of drawing.

1 schematically illustrates a membrane electrode assembly.

FIG. 2 is a graph showing polarization curves for fuel cells with platinum-cobalt alloy electrocatalysts and platinum electrocatalysts for cathode electrodes, both in combination with Nafion® ionomers.

In the following description, certain specific details are set forth in order to provide a thorough understanding of various embodiments of the present description. However, those skilled in the art will understand that the present invention may be practiced without the above detailed description. In other instances, well known structures associated with fuel cells, fuel cell stacks, and fuel cell systems have not been shown or described in detail in order to avoid unnecessary ambiguity in embodiments.

Unless the text requires otherwise, terms such as "comprises" and "comprising", and variations thereof, throughout the specification and claims, should be interpreted in an inclusive sense including, but not limited to.

In this specification, "an embodiment" or "an embodiment" means that a particular form, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases in "one embodiment" or "an embodiment" in various parts of this specification are not always necessary when referring to the same embodiment. In addition, special forms, structures, or properties may be combined in any suitable manner in one or more embodiments.

1 schematically illustrates an exemplary membrane electrode assembly 10 (MEA). As mentioned at the outset, membrane electrode assemblies (MEAs) typically comprise an electrocatalyst layer 12,14 and a proton exchange membrane 20 (“PEM”) disposed between gas diffusion layers 16,18 (“GDL”). ). Electrocatalyst layers 12,14 generally contain electrocatalysts such as noble metals, non-noble metals and / or alloys thereof, in combination with ionomers, to increase quantum conductivity in the electrocatalyst layer. Gas diffusion layers 16 and 18 (" GDL ") are typically substrates 22 and 24, such as fibrous paper, optional auxiliary layers 26 and 28, such as layers comprising carbonaceous particles and, for example, PTFE and //. Or binders of ionomers.

As mentioned at the outset, an important characteristic of the electrocatalyst layer is water management because of its large effect on performance. If the electrocatalyst layer is unable to adequately remove excess water, fuel cell performance can be adversely affected by excessive mass transport losses, especially when operating with oxidants at high current densities where large amounts of water are produced. . In particular, any electrocatalyst, such as a platinum-cobalt alloy electrocatalyst, has less kinematic loss than a pure platinum catalyst. This performance gain is however not realized as the current density increases.

As shown in FIG. 2, two membrane electrode assemblies (MEAs) with the same anode electrode and the same membrane but with different cathode electrocatalysts were tested for fuel cell performance. The anode electrocatalyst is platinum on the graphite support and has a loading of 0.1 mg Pt / cm ² . The membrane is E.I. NRE211, Nafion® based polymer electrolyte membrane supplied by DuPont de Nemours and Company. The cathode electrocatalyst for one of the membrane electrode assemblies (MEAs) was platinum on the graphite support and mixed with a Nafion® binder, the cathode electrocatalyst for the other membrane electrode assembly (MEA) was a platinum-cobalt alloy on the graphite support and Nafion® Mixed with binder. The cathodes both have a loading of 0.4 mg Pt / cm ² . At 1.0 A / cm ² , the test conditions are as follows:

Fuel type 80% H ₂ , remaining N ₂ Fuel stoichiometry 1.8 Fuel pressure 2.2 bara Fuel relative humidity 60% Air stoichiometry 1.8 Air pressure 2.0 bara Air relative humidity 60% Refrigerant inlet temperature 65 ℃ Refrigerant outlet temperature 79 ℃

Electrocatalyst layers with platinum-cobalt alloys are believed to have greater mass transport losses at higher current densities than electrocatalyst layers containing pure platinum due to water retention. Thus, incorporating a hydrophobic additive compatible with the catalyst layer elements into the electrocatalyst layer reduces water retention and enhances fuel cell performance at high current densities.

Polyperferyl alcohol (PFA) has been identified as a particularly suitable hydrophobic additive for the electrocatalyst layer for electrochemical fuel cells because it polymerizes at temperatures below the decomposition temperature of most ionomers such as Nafion®. The literature indicated that Nafion® membranes for methanol fuel cells were prepared by in situ acidic catalytic polymerization of perferyl alcohol in the Nafion® structure. It has been suggested that the hydrophilicity of the monomeric perferyl alcohol permit uniformity and penetrate thoroughly into the hydrophilic structure of Nafion®, thereby forming Nafion®-polyperferyl alcohol (PFA) nanocomposite membranes with reduced methanol penetration. Methanol penetration problems are faced directly in methanol fuel cells due to the use of liquid methanol fuels, but not in fuel cells operating on gaseous fuels such as hydrogen gas.

Without being bound by theory, the water management of the electrocatalyst layer is at least partially hydrophobic within the relatively hydrophilic ionomer network when polyperferyl alcohol (PFA) is used in the electrocatalyst layer having ionomers. Change the property. In addition, the ion conductivity should not be affected when polyperferyl alcohol (PFA) is present in an appropriate amount. Polyperferyl alcohol (PFA) can enhance the adhesion strength and / or tensile strength between the ionomer and the electrocatalyst of the electrocatalyst layer, thereby reducing the size change of the electrocatalyst layer due to hydration / dehydration; and Cracks can be prevented from being formed on the surface of the electrocatalyst layer.

In one embodiment, polyperferyl alcohol (PFA) is uniformly distributed in the electrocatalyst layer. In another embodiment, polyferryl alcohol (PFA) is unevenly distributed within the electrocatalyst layer. For example, the concentration of polyperferyl alcohol (PFA) through the thickness of the electrocatalyst layer may vary in the z direction (ie, from the polymer electrolyte membrane (PEM) to the gas diffusion layer (GDL)). In addition, or alternatively, the concentration of polyperferyl alcohol (PFA) of the electrocatalyst layer can be changed in the xy direction (relative to the surface of the electrocatalyst layer), for example from the inlet of the fuel cell to the outlet of the fuel cell.

In another embodiment, polyperferyl alcohol (PFA) is a layer such as, for example, a layer between an electrocatalyst layer and a gas diffusion layer (GDL) or a layer between a polymer electrolyte membrane (PEM) and an electrocatalyst layer to enhance hydrophobicity. It may be in the form. Again, the polypuryl alcohol (PFA) may be uniform or nonuniform in the xy direction.

The amount of polyperferyl alcohol (PFA) of the electrode, after polymerization, thus ranges from about 0.1 wt% of the total ionomer of the electrocatalyst layer to about 20 wt% of the total ionomer of the electrocatalyst layer, depending on the ionomer penetration of the electrocatalyst layer. Can be in. For example, if polyperferyl alcohol (PFA) is dispersed in the electrocatalyst layer, then the amount of polyperferyl alcohol (PFA) in the resulting electrode after polymerization is preferably less than 8 wt% of the total ionomer of the electrocatalyst layer. This is because the literature states that if the amount of polyperferyl alcohol (PFA) is greater than 8 wt% of the total ionomer, the ion conductivity of the membrane is negatively affected. However, if polyperferyl alcohol (PFA) is applied onto the electrocatalyst layer (i.e. between the electrocatalyst layer and the gas diffusion layer (GDL)), then the amount of polyperferyl alcohol (PFA) at the electrode after polymerization is Although it can be high, for example, it is less than 20 wt% of the total ionomer in the electrocatalyst layer, thereby forming a gradient of hydrophobicity in the z direction of the electrocatalyst layer. When polyperferyl alcohol (PFA) is applied into the electrocatalyst layer without serious penetration into the layer, the effect of quantum conductivity through the electrocatalyst layer is not significantly affected, so in this case the amount of polyperferyl alcohol (PFA) is increased. May be allowed.

Described below are methods of making the electrocatalyst layer and membrane electrode assemblies (MEAs) by using an electrocatalyst composition comprising polyperferyl alcohol (PFA).

Electrocatalyst compositions typically include, for example, precious metals of platinum, ruthenium and iridium; Non-noble metals such as cobalt, nickel, iron, chromium and tungsten; Or electrocatalysts such as combinations or alloys thereof. In certain embodiments, the electrocatalyst is a platinum-cobalt alloy. In another embodiment, the electrocatalyst may be a non-noble metal such as described in issued US patent application 2004/0096728. The electrocatalyst may be supported on a graphite support material such as carbon black or carbide or other oxidatively stable support or on an electrically conductive material such as carbonaceous. The electrocatalyst composition may optionally include pore precursors such as methyl cellulose, durene, camphene, camphor and naphthalene, which are removed in the process of making the electrocatalyst layer to increase porosity. . In addition, the electrocatalyst compositions include, but are not limited to, perfluorinated ionomers, partially fluorinated ionomers or non-fluorinated ionomers; For example, it may optionally contain a polar aprotic solvent such as N-methylpyrrolidinone, dimethylsulfur oxide and N, en-dimethylacetamide. The electrocatalyst composition may also optionally include other additives such as carbonaceous particles and carbon nanotubes and / or nanofibers.

In one embodiment, monomeric perferyl alcohol is mixed with the electrocatalyst composition by any method known in the art, such as stirring, shear mixing, microfluidization, and ultrasonic mixing. The monomeric perferyl alcohol may be dispersed in a solvent such as isopropanol, ethanol, methanol, deionized water or mixtures thereof or used in the form of a pure solution before being added to the electrocatalyst composition. Optionally, acidic catalysts may be added to the electrocatalyst composition to induce and / or enhance the polymerization process.

The electrocatalyst composition may be applied onto the sheet material by any method known in the art, such as knife coating, slot coating, dip-coating, microgravure coating, spray and screen-printing. Can be. In one embodiment, the sheet material is the surface of the electrocatalyst layer. In another embodiment, the sheet material may be formed on the surface of the gas diffusion layer (GDL) to form polytetrafluoroethylene, polyester and gas diffusion electrodes or of the polymer electrolyte membrane (PEM) to form a catalyst coated membrane (CCM). It can be a transfer material such as a polyimide sheet that can be used to decal transfer the electrocatalyst layer to the surface.

In another embodiment, the electrocatalyst composition is applied onto the surface of the sheet material to form the electrocatalyst layer, and then monomer perperyl alcohol is applied to the surface of the electrocatalyst layer by any method known in the art, such as those described above. Is applied onto. In some embodiments, monomeric perferyl alcohol may also be applied to the surface of the sheet material prior to application of the electrocatalyst composition.

In this embodiment, the monomeric perperyl alcohol and the electrocatalyst layer are subjected to injection conditions prior to polymerization to form a non-uniform distribution of the perperyl alcohol of the electrocatalyst layer, such as, for example, the change of perperyl alcohol through the thickness of the electrocatalyst layer. Can be dependent. In another embodiment, monomeric perperyl alcohol may be uniformly injected into the electrocatalyst layer by using a sufficient amount of monomeric perperyl alcohol and / or subject the monomeric perperyl alcohol and the electrocatalyst layer to appropriate injection conditions. Injecting monomeric perperyl alcohol into the electrocatalyst layer can be controlled by varying the amount of the perperyl alcohol and / or controlled by implantation conditions such as implantation temperature and time, to achieve the desired degree of change through the thickness of the electrocatalyst layer. have.

Polymerization of the monomeric perferyl alcohol may occur during and / or before adhesion of the membrane electrode assembly (MEA). For example, monomeric perferyl alcohol can be polymerized during or after application to the sheet material and prior to assembly of the membrane electrode assembly (MEA). Alternatively, by assembling the membrane electrode assembly (MEA) with an electrocatalyst layer containing monomeric (unpolymerized) perperyl alcohol and then subjecting the membrane electrode assembly (MEA) to adhesion conditions similar to the required polymerization conditions. The polymerization reaction may occur simultaneously with the contact of the membrane electrode assembly (MEA) elements. In another example, the monomeric perferyl alcohol may be partially polymerized during or after application to the sheet material and further polymerized during membrane electrode assembly (MEA) adhesion.

Polymerization conditions can include, for example, a polymerization temperature heated to a temperature of about 80 ° C. to about 140 ° C. and a polymerization time of about 5 seconds to about 15 minutes. The polymerization time depends on the polymerization temperature and the amount of perperyl alcohol. The polymerization time may be, for example, about 5 to 10 minutes for low polymerization temperatures and large amounts of perperyl alcohol, but may range from about 1 to 2 minutes for high polymerization temperatures and small amounts of perferyl alcohol. In some cases, the perferyl alcohol can be crosslinked by exposure to ultraviolet light, such as, for example, by Mercury lamps.

In some embodiments, the degree of polymerization of perperyl alcohol and / or the amount of perperyl alcohol in the electrocatalyst layer or in the electrocatalyst layer is non-uniform in the xy-direction to better control hydrophobicity in other regions of the fuel cell. In one embodiment, in order to improve the water removal process, the region of the electrocatalyst that is more wetted during operation of the fuel cell (eg, the outlet region of the fuel cell compared to the inlet region) may contain a high concentration of monomer perferyl alcohol and Higher degree of polymerization of monomeric perferyl alcohol may be used. In addition, loading monomeric perferyl alcohol into the electrocatalyst composition can be varied when applied to the sheet material. In another example, loading monomeric perferyl alcohol can be varied when applied to the electrocatalyst layer. In another example, to change the degree of polymerization, the polymerization conditions can be changed along the xy direction of the electrocatalyst layer.

In another embodiment, the ionomer layer may also be used between the polymer electrolyte membrane (PEM) and the electrocatalyst layer and / or between the electrocatalyst layer and the gas diffusion layer (GDL). The ionomer layer may also contain monomeric perperyl alcohol and then polymerize after being applied to the surface of the polymer electrolyte membrane (PEM) and / or the electrocatalyst layer, for example during the membrane electrode assembly (MEA) or It may be polymerized immediately after application. Again, the ionomer layer may be applied by any method known in the art, as described above, and may be uniform or nonuniform with respect to the flat surface of the catalyst layer.

The following examples are provided for illustrative purposes only, and the invention is not limited thereto.

View 1

Polymerization of Perferyl Alcohol to Form Electrodes

The electrocatalyst composition is prepared by mixing 662 grams of 10% Nafion® solution per weight with 132 grams of platinum-containing catalyst powder, 2 grams of monomeric perperyl alcohol, 6 grams of isopropanol and 290 grams of deionized water. The mixture is then mixed using an ultrasonic mixer and then sprayed onto a fluid diffusion layer consisting of a carbonaceous layer of carbon fiber paper and micropores. The electrode accordingly is then dependent for about 2 to 10 minutes at a temperature of about 140 ° C. to produce the electrode by polyperperyl alcohol (PFA) by polymerizing monomeric perperyl alcohol.

View 2

Polymerization of Perferyl Alcohol to Form Catalyst Coating Membrane

A solution of monomeric perperyl alcohol is prepared by mixing 6 grams of monomeric perperyl alcohol with 12 grams of isopropanol and 6 grams of deionized water. The solution is sprayed onto the cathode electrocatalyst layer of the catalyst coated membrane (CCM). Monomer perferyl alcohol is allowed to penetrate into the cathode electrocatalyst layer at a temperature of 20 ° C. for about 1 hour. After infiltration, the catalyst coating membrane (CCM) is heated at about 140 ° C. for about 2 to about 10 minutes to polymerize the monomer perferryl alcohol, thereby allowing the catalyst coating membrane (PFA) of the cathode electrocatalyst layer to be CCM).

View 3

Polymerization of Perperyl Alcohol as Layer on Carbon / Nafion® Auxiliary Layer

A solution of monomeric perperyl alcohol is prepared by mixing 6 grams of monomeric perferyl alcohol (98% Lancaster) with 12 grams of isopropanol and 6 grams of deionized water. The solution was then sprayed at room temperature onto a gas diffusion layer (GDL) with an auxiliary layer containing Nafion® and carbon black on the surface of the substrate. The sprayed gas diffusion layer (GDL) is placed on a hot plate for about 10 minutes at a temperature of 140 ° C. to polymerize the perferyl alcohol. The final loading of polyperferyl alcohol (PFA) is about 45 wt%.

The polymerized gas diffusion layer (GDL) is a mercury intrusion porosimetry test using AutoFor III supplied by Micromeritics Instrument Corporation, and testing machines (TMI Inc.). It has undergone a series of through-plane permeability using Air Permeance Tester and 58-21 Roughness supplied by. (The through hole is drilled through the bottom jig of the tester and the rubber seal is placed around the test member, so that air is forced through the test member from the top jig to the bottom jig.)

The Mercury Instruction Porositymetry test showed that the mean pore diameter changed from about 0.67 microns without PFA to 1.11 microns with PFA, and the through-plane permeability was 183 mL / min for PFA at an average of 129 mL / min for PFA-free air permeability. It was shown to increase. Perperyl alcohol shrinks as it polymerizes, thus pulling pores wider apart and increasing size and through-plane permeability. This increase in pore size and through-plane permeability can improve water removal and reactant access in addition to increasing hydrophobicity of the electrocatalyst layer when using polyperferyl alcohol (PFA) in the electrocatalyst layer.

All of the above-mentioned US patents, US patent application publications, US patent applications, foreign patents, foreign patent applications and non-patent publications described in the application data sheets and / or referred to herein are hereby incorporated by reference in their entirety.

While the specific steps, elements, examples and applications of the present invention have been shown and described for illustrative purposes only, those skilled in the art can produce modified configurations in view of the above teachings within the spirit and scope of the present application. The description herein is not limited to the details. Accordingly, the invention is limited only by the appended claims.

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Claims (20)

An anode comprising an anode gas diffusion layer and an anode electrocatalyst layer; A cathode comprising a cathode gas diffusion layer and a cathode electrocatalyst layer; And A proton exchange membrane disposed between the anode and the cathode, At least one of the anode electrocatalyst layer and the cathode electrocatalyst layer comprises polyfurfuryl alcohol. The method of claim 1, And the cathode electrocatalyst layer comprises a platinum alloy catalyst. The method of claim 2, And the platinum alloy catalyst is a platinum-cobalt alloy catalyst. The method of claim 2, And the cathode electrocatalyst layer comprises an ionomer. The method of claim 1, Wherein the distribution of the polyperferyl alcohol is non-uniform in the z-direction of at least one of the anode and cathode electrocatalyst layers. The method of claim 1, Wherein the distribution of polyperferyl alcohol is non-uniform in the xy-direction of at least one of the anode and cathode electrocatalyst layers. A catalyst-coated membrane comprising an anode electrocatalyst layer, a cathode electrocatalyst layer and a proton exchange membrane interposed therebetween, At least one of the anode electrocatalyst layer and the cathode electrocatalyst layer comprises polyperferyl alcohol. The method of claim 7, wherein And the cathode electrocatalyst layer comprises a platinum alloy catalyst. The method of claim 8, And the cathode electrocatalyst layer comprises a platinum alloy catalyst. The method of claim 7, wherein Wherein the distribution of polyperferyl alcohol is non-uniform in the z-direction of at least one of the anode and cathode electrocatalyst layers. Applying the electrocatalyst composition to the sheet material; Adding a monomer perferyl alcohol to the electrocatalyst composition; And A method of producing an electrode for an electrochemical fuel cell, comprising the step of adding a monomer perferyl alcohol and applying the catalyst composition to polymerize the monomer perferyl alcohol. The method of claim 11, The electrocatalyst composition further comprises at least one of an ionomer, a polar aprotic solvent, and a pore former. The method of claim 11, And the electrocatalyst composition is applied to the sheet material after the step of adding monomeric perferyl alcohol to the electrocatalyst composition. The method of claim 11, Wherein said electrocatalyst composition is applied to a sheet material prior to adding monomer perferyl alcohol to said electrocatalyst composition. The method of claim 14, Further comprising applying the monomer perferryl alcohol and the electrocatalyst composition to a time and injection temperature prior to the step of polymerizing the monomer perferryl alcohol. The method of claim 15, Wherein the injection temperature is from about 20 ° C. to about 85 ° C. 16. The method of claim 11, And the sheet material is selected from the group consisting of a gas diffusion layer, a proton exchange membrane, and a transfer material. The method of claim 11, And polymerizing the monomeric perferyl alcohol comprises subjecting the monomeric perferyl alcohol to a temperature of at least about 120 ° C. The method of claim 11, And wherein said monomeric perferyl alcohol comprises subjecting said monomeric perferyl alcohol to a temperature of at least about 140 ° C. The method of claim 11, And polymerizing the monomer perferryl alcohol comprises subjecting the monomer perferryl alcohol to an acidic environment.

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