WO2010012717A1 - Production of thin catalyst layers - Google Patents

Abstract

The invention relates to a method for applying a metal onto a non-metal support substrate for producing a thin, porous layer, in which a first metal component is applied onto the non-metal support substrate, wherein the first metal component is more reactive than the metal to be applied. Then, the first metal component applied is replaced by the metal to be applied to the non-metal support substrate through a redox reaction.

Description

 Preparation of thin catalyst layers

description

The invention relates to a method for applying a metal to a carrier substrate for producing a thin, porous layer.

Thin, porous layers of a metal on a carrier substrate, usually a non-metallic carrier substrate, are used, for example, in fuel cells. The thin porous layer of the metal is generally a catalytically active layer which is applied to an ion-conducting membrane. Usually, such catalyst layers are applied to both sides of the membrane. The membrane provided with the catalyst layers is positioned between two porous gas distribution layers. Through the gas distribution layers, the respective reaction gases are conducted close to the membrane. At the same time, the gas distribution layer also serves to supply and discharge the electrons taken up or released by the reactants. In the catalyst layer, which is located between the membrane and the gas distribution layer, the actual reduction or oxidation reaction takes place. The membrane in turn ensures ionic current transport in the fuel cell. Another object of the membrane is to form a gas-tight barrier between the two electrodes.

Currently, the catalyst layer is either applied directly to the membrane during production or to the gas distribution layer. Catalytically coated gas distribution layers are generally referred to as gas diffusion electrodes.

Usually, the catalyst layers are applied to the gas diffusion layer or to the membrane by printing, spraying, knife coating, rolling, brushing and brushing. Alternatively, it is also known to first prepare a catalyst layer on a separating film and then to relaminate it onto the membrane or onto the gas distributor layer. Usually, the catalyst layer is relaminated onto the membrane.

The electrode layers produced in this way generally have a layer thickness in the range from 15 to 100 μm and have a content of catalytically active material of about 1 mg / cm ² .

The application of the catalyst layer is generally carried out by a homogenized ink containing the catalytically active material. In addition, in the ink Cherweise at least one solvent and optionally additional additives, such as ionomers.

For optimum operation of the fuel cell, it is necessary for the catalyst layer to be both electrically conductively connected to the gas distribution layer and ionically conductive to the membrane. This double contact with the membrane and gas distributor layer must be given over the entire thickness of the catalyst layer. An optimal connection to the gas distribution layer or to the membrane, however, results only in the directly adjacent area. For the remaining areas special measures must be taken to guarantee the ionic and electrical contacting of the catalyst. The electrical connection of the catalyst layer takes place, for example, in the case of a supported catalyst by the use of electrically conductive carrier substances, for example of carbon blacks. With unsupported catalysts, the conductivity of the metallic active component is often sufficient to ensure electrical contact. An improvement in the electrical contact between the catalyst layer and the gas diffusion layer can also take place, for example, by pressing the single cell. The compression also improves the ionic conductivity between the membrane and the catalyst layer. When the electrolyte contained in the membrane is liquid, the liquid electrolyte is partially pressed into the catalyst layer by the pressing and allows the ionic coupling of regions of the catalyst layer which are not in direct contact with the membrane. Depending on the manufacturing technique, contact mediators are also used to improve the ionic contact. For example, ionomers, that is, ionic conductive polymers that enforce the catalyst layer, are used for this purpose.

However, any measures to improve the bonding of the catalyst layer to the gas distribution layer or to the membrane may also have negative effects on the operation of the cell. Thus, for example, an excess of ionomer or else excessive compression can easily lead to a blockage of the catalytically active centers and a hindrance to the transport or removal of the educts and products. In order to dispense with additional measures to improve the contact of gas distribution layer and membrane, it is desirable to make the catalyst layer as thin as possible.

However, the controlled application of thin catalyst layers is technically demanding and even small inhomogeneities in the catalyst coating can lead to significant performance losses. In order to ensure a sufficient amount of catalyst substance per unit area at a low catalyst layer thickness, unsupported catalysts must be used. These However, they usually have a lower catalyst utilization compared to supported catalysts.

A thin layer is achieved, for example, by Physical Vapor Deposition (PVD), Chemical Vapor Deposition (CVD) or by sputtering. Other vacuum-based deposition methods are also used to create a thin layer on a substrate.

However, layers made by known methods are generally very dense. As a result, the effectiveness of the catalyst layer produced is significantly reduced by a high mass transport resistance. An improvement in the porosity of the catalyst layer can be achieved, for example, in PVD processes by reducing the substrate temperature or increasing the distance between the source and the substrate. However, a sufficient improvement of the mass transport can not be achieved.

Alternatively, it is known, for example, in PVD processes, to simultaneously apply two components either to the gas distribution layer or to the membrane. The second component is selectively removed after the coating, for example by an etching process. As a result, the required porosity is obtained. However, the required etching process limits the applicability of this method and is therefore of particular interest for the production of catalyst layers for solid fuel cells.

The object of the present invention is to produce a thin catalyst layer which has a sufficiently large porosity in order not to reduce the mass transport resistance or only to a small extent compared to a conventional catalyst layer.

The object is achieved by a method for applying a metal to a carrier substrate for producing a thin, porous layer, comprising the following steps:

(a) applying a first metal component to the carrier substrate, wherein the first metal component is less noble than the metal to be applied,

(b) replacing the first metal component applied in step (a) with the metal to be applied to the carrier substrate by a redox reaction. For the purposes of the present invention, the term "thin layer" means that the layer has a layer thickness of less than 10 μm, preferably less than 5 μm and particularly preferably less than 1 μm.

In the redox reaction, the metal to be applied to the carrier substrate is reduced by the first metal component and deposits on the carrier substrate. At the same time, the first metal component oxidizes and dissolves from the carrier substrate. The metal to be deposited precipitates highly dispersed with primary particle sizes generally less than 10 nm. In the case of a porous carrier substrate, the metal to be applied also penetrates into the substrate, thereby additionally improving the electrical connection. The metallic layer obtained by the method according to the invention on the carrier substrate is very well connected. Another lamination step is not required.

The monitoring of the process parameters of the method according to the invention makes it possible to apply the metal reproducibly and homogeneously to the carrier substrate. Also, the surface concentration of the metal on the carrier substrate for each application can be set exactly. As a result, for example, a smaller surface loading of the metal applied to the carrier substrate is possible. In particular, in the case of noble metals, as they are usually used as a catalytically active substance, this is advantageous, since only a smaller amount of the metal is needed.

The first metal component, which is less noble than the metal to be applied to the carrier substrate and which is first applied to the carrier substrate in step (a), is preferably a metal of the third to fifth main group or a metal of the subgroup elements of the first period of the periodic table of the elements. Preferably, the metal of the first metal component is selected from the group consisting of aluminum, iron, cobalt, nickel, copper or zinc. Most preferably, the metal of the first component is aluminum or iron. In addition to the use of only one metal as the first metal component, it is alternatively also possible to use mixtures or alloys of two or more metals. However, the use of only one metal is preferred.

The carrier substrate produced by the method according to the invention and provided with a thin, porous layer of a metal is used in particular in a fuel cell. Here, the carrier substrate is, for example, a membrane used in a fuel cell or a gas diffusion layer used in a fuel cell. The thin, porous layer that is applied to the carrier substrate is a catalytically active layer. To produce the catalytically active layer, the metal to be applied to the carrier substrate is catalytically active. When using the with the thin, porous layer coated carrier substrate in a fuel cell, the metal to be applied in particular electrocatalytically active.

The metal which is applied to the carrier substrate is therefore preferably selected from the group consisting of platinum, palladium, ruthenium and gold. The metal to be applied to the carrier substrate is particularly preferably platinum or palladium.

Any metallic or non-metallic material that is usually used as the carrier substrate and is known to the person skilled in the art is suitable as the material for the carrier substrate. Preferably, a non-metallic material, in particular carbon, a polymer or a ceramic, is used for the carrier material. Particularly preferred as material for the carrier substrate is carbon, for example in the form of carbon blacks or graphites.

When using the carrier substrate produced in accordance with the invention with a thin, porous layer of a metal in a fuel cell, the carrier substrate may be, for example, a membrane or a gas distributor layer. If the carrier substrate is a membrane, the material for the carrier substrate is preferably a polymer. When the support substrate is a gas diffusion layer used in a fuel cell, carbon, a polymer or a ceramic may be used as the material for the support substrate.

If the non-metallic carrier substrate is a membrane, as used in a fuel cell, suitable polymers are, for example, epoxy resins, polyamides or polyimides.

If the non-metallic carrier substrate is a gas distributor layer, as used for example in a fuel cell, suitable polymers are also epoxy resins, polyamides or polyimides.

However, particularly preferred as a material for a gas distribution layer is carbon, for example as carbon black or graphite.

In addition to polymers, ceramics or carbon, glass, (mixed) oxides, carbides and metals are also suitable as material for the carrier substrate.

In addition to use in a fuel cell, however, the non-metallic carrier substrate formed by the method with the thin, porous layer of a metal can be used, for example, in applications in which supported

Catalysts are used. Such applications are for example ranfilter, such as palladium or platinum catalysts on a metal mesh or ceramic.

The first metal component is preferably applied to the carrier substrate from the vapor phase in step (a). By applying the first metal component from the vapor phase, uniform thin layers can be achieved. Suitable methods for applying the first metal component to the carrier substrate are, for example, PVD methods, CVD methods or sputtering.

In PVD processes, the substance with which a substrate is to be coated is vaporized by bombardment with laser beams, magnetically deflected ions or electrons or by an arc discharge. The substance is generally initially solid. The vaporized material moves to the substrate, impinges on it, and deposits. In general, PVD processes are carried out under vacuum. The pressure is generally in the range of 10 ^"4 Pa to about 10 Pa. For targeted coating, it is possible to guide the vaporized substrate by electric fields in order to obtain a guided movement of the vaporized substance towards the substrate.

In sputtering, which belongs to the group of PVD methods, a target containing the substance to be coated on the substrate is bombarded with ions. As a result, atoms of the substance are released from the target. The atoms ejected by the bombardment with the ions condense on the substrate and form a layer. The ion source is generally a DC gas discharge source.

An advantage of sputtering is that no alloying of alloys occurs when coated with alloys. The adhesion of the layer is often better than in vapor-deposited layers.

In contrast to PVD processes, CVD processes involve a chemical reaction on the surface of the substrate to be coated. At least one gaseous starting compound (starting material) and at least two reaction products, at least one of which is present in the solid phase, are involved in this reaction. In the CVD method, a solid component is deposited on the heated surface of the substrate due to the chemical reaction from the gas phase.

In order to promote surface reactions to competing gas phase reactions and thus avoid the formation of solid particles, CVD processes are generally operated at reduced pressure. Typical pressures are in the range of 1 to 1000 Pa. Unlike physical procedures is at CVD method in particular also a coating of complex three-dimensionally shaped surfaces possible. For example, even the finest pits on its inside can be evenly coated.

The process parameters to be set are dependent on the material of the substrate with the metal to be applied in all coating processes. Suitable process parameters are known to the person skilled in the art.

After the application of the first metal component to the carrier substrate, in a redox reaction the first metal component is replaced by the metal to be applied to the carrier substrate, which is generally catalytically active. The redox reaction, in which the first metal component is replaced by the metal to be applied to the carrier substrate, is generally carried out in a solvent. The implementation of the redox reaction in a solvent has the advantage that the oxidizing during the redox reaction first metal component can go directly into solution. At the same time, it is also possible to realize a more uniform contact of the metal to be applied to the carrier substrate with the first metal component and the carrier substrate. Since the first metal component is less noble than the metal to be applied to the carrier substrate, the metal to be deposited is spontaneously reduced by the first metal component and thus deposited on the carrier substrate. The metal to be deposited generally precipitates highly dispersed with primary particle sizes of significantly less than 10 nm on the carrier substrate. To a small extent, the metal to be applied also penetrates into the carrier substrate, thereby improving the coupling of the applied layer. In particular, when using the carrier substrate with the metal layer applied thereto in fuel cells, the electrical coupling of the catalyst layer is improved. The applied by the process layer is very well connected to the carrier substrate. A subsequent lamination step is not required.

In contrast to a layer applied directly by, for example, a PVD, CVD or sputtering process, the layer formed by the redox reaction is sufficiently porous that the function of a fuel cell is not restricted.

In order to be able to carry out the redox reaction in a solvent, it is necessary for both the first metal component and the metal to be applied to the carrier substrate to dissolve in the form of the cation in the solvent. Suitable solvents are, for example, water, alcohols, cyclic or linear ether compounds, aprotic solvents, molten salts or ionic liquids. In particular, when using water as a solvent, it is necessary to place special value on the correct adjustment of the pH. The The pH is adjusted by methods known to the person skilled in the art, for example by using carbonates, aqueous HCl, buffer solutions.

The use of water or organic solvents is only suitable if the solvent does not oxidize the first metal component. If water is already a suitable oxidizing agent for the first metal component, it is advantageous to choose a chemically inert solvent other than water.

When alcohols are used as the solvent, for example, mono- or polyhydric alcohols can be used. Suitable alcohols are, for example, ethanol, propanol, butanol or higher alcohols. The alcohols can be linear or branched.

A suitable ether compound is, for example, crown ether. Suitable aprotic solvents are, for example, nitriles, such as acetonitrile or ketones.

However, ionic liquids are particularly preferred as solvents since, owing to the lack of vapor pressure of the ionic liquids in a possible subsequent heat treatment step, no evaporation-induced delamination of the applied metal layer can take place.

Ionic liquids in the context of the present application are, in particular, organic salts which are already liquid at temperatures of less than 180 ^° C. Preferably, the ionic liquids have a melting point of less than 180 ⁰ C, in particular, the melting point is in a range of -50 ° C to 150 ⁰ C.

Ionic liquids, which are already present at room temperature and in liquid state, are described, for example, in KN Marsh et al., Fluid Phase Equilibira 219 (2004), pages 93-98 and in JG Huddieton et al., Green Chemistry 2001, 3, Pages 156-164.

Suitable ionic liquids are, for example, those which have cations which are selected from the compounds of the formulas (Ia) to (Iw):

(Ia) (Ib) (Ic)

(Id) (Ie) (If)

(ig) (ig ¹ ) (Ih)

(Ii) (U ')

(Ik) (Ik ') (H)

(Im) (In) (In)

(Iq ") (Ir) (Ir ')

(Ir ") (Is) (It)

(Iu) (Iv) (Iw)

and oligomers containing these structures.

Further suitable cations are compounds of the general formula (Ix) and (Iy)

R ^z R ^z

3 ^{l +} 1 ^{l +} 1

R-P-R S-R

I I R R

(Ix) (iy)

and oligomers containing this structure.

In the abovementioned formulas (Ia) to (Iy)

• the radical R is hydrogen, a carbon-containing organic, saturated or unsaturated, acyclic or cyclic, aliphatic, aromatic or araliphatic, unsubstituted or interrupted by 1 to 5 heteroatoms or functional groups radical having 1 to 20 carbon atoms; and

the radicals R ¹ to R ⁹ independently of one another represent hydrogen, a sulfo group or a carbon-containing organic, saturated or unsaturated, acyclic or cyclic, aliphatic, aromatic or araliphatic, unsubstituted or by 1 to 5 heteroatoms or functional groups Ie groups interrupted or substituted radical having 1 to 20 carbon atoms, wherein the radicals R ¹ to R ⁹ , which in the abovementioned formulas (I) to a carbon atom (and not to a heteroatom) are bonded, additionally for halogen or a functional Group can stand; or

two adjacent radicals from the series R ¹ to R ⁹ together also for a divalent, carbon-containing organic, saturated or unsaturated, acyclic or cyclic, aliphatic, aromatic or araliphatic, unsubstituted or by 1 to 5 heteroatoms or functional Groups interrupted or substituted radical having 1 to 30 carbon atoms.

Suitable hetero atoms in the definition of the radicals R and R ¹ to R ^{9 are in} principle all heteroatoms in question which are capable of formally a -CH ₂ -, a -CH =, a -C≡ or a = C = group to replace. If the carbon-containing radical contains heteroatoms, oxygen, nitrogen, sulfur, phosphorus and silicon are preferred. Particular preferred groups are -O-, -S-, -SO-, -SO ₂ -, -NR'-, -N =, -PR'-, -PR ' ₂ and -SiR' ₂ - called, where the radicals R 'are the remainder of the carbon-containing radical. The radicals R ¹ to R ⁹ are, in the cases in which those in the above formulas (I) to a carbon atom (and not to a heteroatom) bound also be bound directly via the heteroatom.

Suitable functional groups are in principle all functional groups which may be bonded to a carbon atom or a heteroatom. Suitable examples are -OH (hydroxy), = 0 (in particular as a carbonyl group), _-NH2 (amino), = NH (imino), -COOH (carboxy), _-CONH2 (carboxamide), _-SO3H (sulfo ) and -CN (cyano). Fractional groups and heteroatoms can also be directly adjacent, so that combinations of several adjacent atoms, such as -O- (ether), -S- (thioether), -COO- (ester), -CONH- (secondary amide) or -CONR'- (tertiary amide) are also encompassed, for example di (dC ₄ alkyl) amino, C ₁ -C ₄ - alkyloxycarbonyl or C ₄ alkyloxy.

Halogens are fluorine, chlorine, bromine and iodine.

The radical R preferably stands for

• unbranched or branched, unsubstituted or one to several times with

Hydroxyl, halogen, phenyl, cyano, C ₁ - to C ₆ -alkoxycarbonyl and / or sulfonic acid-substituted C ₁ - to C -alkyl having in total 1 to 20 carbon atoms, such as, for example, methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, 2-methyl

1-propyl (isobutyl), 2-methyl-2-propyl (tert-butyl), 1-pentyl, 2-pentyl, 3-pentyl, 2-methyl-i-butyl, 3-methyl-1-butyl, 2-methyl-2-butyl, 3-methyl-2-butyl, 2,2-dimethyl-propyl, 1-hexyl, 2-hexyl, 3-hexyl, 2-methyl-i-pentyl, 3-methyl-i-pentyl, 4-methyl-i-pentyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl-2- pentyl, 2-methyl-3-pentyl, 3-methyl-3-pentyl, 2,2-dimethyl-i-butyl, 2,3-dimethyl-i-butyl, 3,3-dimethyl-i-butyl, 2- Ethyl 1-butyl, 2,3-dimethyl-2-butyl, 3,3-dimethyl-2-butyl,

1-heptyl, 1-octyl, 1-nonyl, 1-decyl, 1-undecyl, 1-dodecyl, 1-tetradecyl, 1-hexadecyl, 1-octadecyl, 2-hydroxyethyl, benzyl, 3-phenylpropyl, 2-cyanoethyl, 2- (methoxycarbonyl) -ethyl, 2- (ethoxycarbonyl) -ethyl, 2- (n-butoxycarbonyl) -ethyl, trifluoromethyl, difluoromethyl, fluoromethyl, pentafluoroethyl, heptafluoropropyl, heptafluoroisopropyl, nonafluorobutyl, nonafluoroisobutyl, undecylfluoropentyl,

Undecylfluoroisopentyl, 6-hydroxyhexyl and propylsulfonic acid;

Glycols, butylene glycols and their oligomers having from 1 to 100 units and a hydrogen or a C 1 to C ₈ alkyl as end group, such as, for example, R ^A O- (CHR ^B -CH ₂ -O) _n -CHR ^B -CH ₂ - or

R 1 is - (CH ₂ CH ₂ CH ₂ CH ₂ O) _n -CH ₂ CH ₂ CH ₂ CH ₂ O- with R ^A and R ^{B is} preferably hydrogen, methyl or ethyl and n is preferably 0 to 3, in particular 3-oxabutyl, 3-oxapentyl, 3,6-dioxaheptyl, 3,6-dioxaoctyl, 3,6,9-trioxadecyl, 3,6,9-trioxa-undecyl, 3,6,9, 12-tetraoxatridecyl and 3,6,9, 12-tetraoxatetradecyl; • vinyl; and

N, N-di-C ₁ to C ₆ alkylamino such as N, N-dimethylamino and N, N-diethylamino.

Particularly preferably, the radical R is unbranched and unsubstituted Cr to Ciβ-alkyl, such as methyl, ethyl, 1-propyl, 1-butyl, 1-pentyl, 1-hexyl, 1-heptyl, 1-octyl, 1-decyl, 1-dodecyl, 1-tetradecyl, 1-hexadecyl, 1-octadecyl, in particular methyl, ethyl, 1-butyl and 1-octyl, and CH ₃ O- (CH ₂ CH ₂ O) _n -CH ₂ CH ₂ - and CH ₃ CH ₂ O- (CH ₂ CH ₂ O) _n -CH ₂ CH ₂ - where n is 0 to 3.

The radicals R ¹ to R ⁹ are preferably each independently

• hydrogen;

• halogen;

• a functional group; Optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles substituted and / or interrupted by one or more oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino groups CrC-is alkyl;

Optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles and / or by a or one or more oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino groups interrupted C ₂ -C ₈ alkenyl;

• where appropriate by functional groups, aryl, alkyl, aryloxy, alkyloxy, halo-, heteroatoms and / or heterocycles C ₆ -C ₂ aryl;

• optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles substituted _C5-Ci2 cycloalkyl;

• optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles substituted _C5-Ci2 cycloalkenyl; or

• an optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles substituted five- to six-membered, oxygen, nitrogen and / or sulfur atoms containing heterocycle; or

two adjacent radicals together for

• an unsaturated, saturated or aromatic, optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles and optionally substituted by one or more oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted Imino groups broken ring.

C₆F₁₃, C₈F₁₇, C₁₀F₂₁, C₁₂F₂₅), Chlormethyl, 2-Chlorethyl, Trichlormethyl, 1 ,1-Dimethyl-2-chlorethyl, Methoxymethyl, 2-Butoxyethyl, Diethoxymethyl, Diethoxyethyl, 2-lsopropoxyethyl, 2-Butoxypropyl, 2-Octyloxyethyl, 2-Methoxyisopropyl, 2-(Methoxycarbonyl)-ethyl, 2-(Ethoxycarbonyl)- ethyl, 2-(n-Butoxycarbonyl)-ethyl, Butylthiomethyl, 2-Dodecylthioethyl, 2-Phenyl- thioethyl, 5-Hydroxy-3-oxa-pentyl, 8-Hydroxy-3,6-dioxa-octyl, 1 1-Hydroxy-3,6,9-trioxa- undecyl, 7-Hydroxy-4-oxa-heptyl, 11-Hydroxy-4,8-dioxa-undecyl, 15-Hydroxy-4,8,12- trioxa-pentadecyl, 9-Hydroxy-5-oxa-nonyl, 14-Hydroxy-5,10-dioxa-tetradecyl,Optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles substituted d- to C-is-alkyl is preferably methyl, ethyl, 1-propyl, 2-propyl, 1-butyl , 2-butyl, 2-methyl-1-propyl (isobutyl), 2-methyl-2-propyl (tert-butyl), 1-pentyl, 2-pentyl, 3-pentyl, 2-methyl-1 butyl, 3-methyl-1-butyl, 2-methyl-2-butyl, 3-methyl-2-butyl, 2,2-dimethyl-1-propyl, 1-hexyl, 2-hexyl, 3-hexyl, 2- Methyl 1-pentyl, 3-methyl-1-pentyl, 4-methyl-1-pentyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl-2-pentyl, 2-methyl 3-pentyl, 3-methyl-3-pentyl, 2,2-dimethyl-1-butyl, 2,3-dimethyl-1-butyl, 3,3-dimethyl-1-butyl, 2-ethyl-1-butyl, 2,3-dimethyl-2-butyl, 3,3-dimethyl-2-butyl, heptyl, octyl, 2-ethylhexyl, 2,4,4-trimethylpentyl, 1,1,3,3-tetramethylbutyl, 1- Nonyl, 1-decyl, 1-undecyl, 1-dodecyl, 1-tridecyl, 1-tetradecyl, 1-pentadecyl, 1-hexadecyl, 1-heptadecyl, 1-octadecyl, cyclopentylmethyl, 2-cyclopentylethyl, 3-cyclopentylpropyl, Cyclohexylmethyl, 2-cyclohexylethyl, 3-cyclohexylpropyl, benzyl (phenylmethyl), diphenylmethyl (benzhydryl), triphenylmethyl, 1-phenylethyl, 2-phenylethyl, 3-phenylpropyl, a, a-dimethylbenzyl, p-tolylmethyl, 1 (p-butylphenyl) ethyl, p-chlorobenzyl, 2,4-dichlorobenzyl, p-methoxybenzyl, m-ethoxybenzyl, 2-cyanoethyl, 2-cyanopropyl, 2-methoxycarbonylethyl, 2-ethoxycarbonylethyl, 2-butoxycarbonylpropyl, 1, 2-di- (methoxycarbonyl) -ethyl, methoxy, ethoxy, formyl, 1, 3 Dioxolan-2-yl, 1, 3-dioxan-2-yl, 2-methyl-1,3-dioxolan-2-yl, 4-methyl-1,3-dioxolan-2-yl, 2-hydroxyethyl, 2- Hydroxypropyl, 3-hydroxypropyl, 4-hydroxybutyl, 6-hydroxyhexyl, 2-aminoethyl, 2-aminopropyl, 3-aminopropyl, 4-aminobutyl, 6-aminohexyl, 2-methylaminoethyl, 2-methylaminopropyl, 3-methylaminopropyl, 4- Methylaminobutyl, 6-methylaminohexyl, 2-dimethylaminoethyl, 2-dimethylaminopropyl, 3-dimethylaminopropyl, 4-dimethylaminobutyl, 6-dimethylaminohexyl, 2-hydroxy-2,2-dimethylethyl, 2-phenoxyethyl, 2-phenoxypropyl, 3-phenoxypropyl, 4-phenoxybutyl, 6-phenoxyhexyl, 2-methoxyethyl, 2-methoxypropyl, 3-methoxypropyl, 4-methoxybutyl, 6-methoxyhexyl, 2-ethoxyethyl, 2-ethoxypropyl, 3-ethoxypropyl, 4-ethoxybutyl, 6- Ethoxyhexyl, acetyl, C _n F ₂ ( _n +) + (ib) H _{2 a} + b with n equal to 1 to 30, 0 <a <n and b = 0 or 1 (for example CF ₃ , C ₂ F ₅ ,

C ₆ F ₁₃ , C ₈ F ₁₇ , C ₁₀ F ₂₁ , C ₁₂ F ₂₅ ), chloromethyl, 2-chloroethyl, trichloromethyl, 1, 1-dimethyl-2-chloroethyl, methoxymethyl, 2-butoxyethyl, diethoxymethyl, diethoxyethyl, 2 -lisopropoxyethyl, 2-butoxypropyl, 2-octyloxyethyl, 2-methoxyisopropyl, 2- (methoxycarbonyl) -ethyl, 2- (ethoxycarbonyl) -ethyl, 2- (n-butoxycarbonyl) -ethyl, butylthiomethyl, 2-dodecylthioethyl, 2-phenyl thioethyl, 5-hydroxy-3-oxa-pentyl, 8-hydroxy-3,6-dioxa-octyl, 1 1-hydroxy-3,6,9-trioxa undecyl, 7-hydroxy-4-oxa-heptyl, 11-hydroxy-4,8-dioxa-undecyl, 15-hydroxy-4,8,12-trioxa-pentadecyl, 9-hydroxy-5-oxa-nonyl, 14-hydroxy-5,10-dioxa-tetradecyl,

5-Methoxy-3-oxa-pentyl, 8-methoxy-3,6-dioxa-octyl, 11-methoxy-3,6,9-trioxa-undecyl, 7-methoxy-4-oxa-heptyl, 1 1-methoxy 4,8-dioxa-undecyl, 15-methoxy-4,8,12-trioxapentadecyl, 9-methoxy-5-oxa-nonyl, 14-methoxy-5,10-dioxa-tetradecyl, 5-ethoxy-3 - oxa-pentyl, 8-ethoxy-3,6-dioxa-octyl, 1-ethoxy-3,6,9-trioxa-undecyl, 7-ethoxy-4-oxa-heptyl, 1-ethoxy-4,8 dioxa undecyl, 15-ethoxy-4,8,12-trioxa-pentadecyl, 9-ethoxy-5-oxa-nonyl or 14-ethoxy-5,10-oxa-tetradecyl.

C ₂ optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles and / or interrupted by one or more oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino groups - to C-is-alkenyl is preferably vinyl, 2-propenyl, 3-butenyl, cis-2-butenyl, trans-2-butenyl or C _n F2 (na) - (ib) H2a-b with n < 30, 0 <a <n and b = 0 or 1.

When optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles substituted C ₆ - to C ₁₂ -aryl it is preferably phenyl, ToIyI, XyIyI, α-naphthyl, ß-naphthyl, 4th Diphenyl, chlorophenyl, dichlorophenyl, trichlorophenyl, difluorophenyl, methylphenyl, dimethylphenyl, trimethylphenyl, ethylphenyl, diethylphenyl, isopropylphenyl 2,6-dimethylphenyl, 2,4,6-trimethyl- phenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl, 4-bromophenyl, 2-nitrophenyl, 4-nitrophenyl, 2,4-dinitrophenyl, 2,6-dinitrophenyl, 4-dimethylaminophenyl, 4-acetylphenyl, methoxyethylphenyl , Ethoxymethylphenyl, methylthiophenyl, isopropylthiophenyl or tert-butylthiophenyl or C ₆ F _(S-3) H ₃ with 0 <a <5.

When optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles C ₅ - to C ₂ cycloalkyl is preferably cyclopentyl, cyclohexyl, cyclooctyl, cyclododecyl, methylcyclopentyl, dimethylcyclopentyl, methylcyclohexyl, dimethylcyclohexyl , Diethylcyclohexyl, butylcyclohexyl, methoxycyclohexyl, dimethoxycyclohexyl, diethoxycyclohexyl, butylthiocyclohexyl, chlorocyclohexyl, dichlorocyclohexyl, dichlorocyclopentyl, C _n F ₂ (n- ₃ ) - (ib) H _{2 3} -b with n <30, 0 <a <n and b = 0 or 1 and a saturated or unsaturated bicyclic system such as norbornyl or norbornenyl.

When optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles C ₅ - to C ₂ cycloalkenyl is preferably 3-cyclopentenyl, 2-cyclohexenyl, 3-cyclohexenyl, 2.5 -Cyclohexadienyl or C _n F ₂ ( _n - ₃ ) -3 (ib) H 2 ₃ -3b with n <30, 0 <a <n and b = 0 or 1.

An optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles substituted five- to six-membered, oxygen, nitrogen and / or sulfur atoms containing heterocycle is preferably furyl, thiophenyl, pyrryl, Pyridyl, indolyl, benzoxazolyl, dioxolyl, dioxo, benzimidazolyl, benzthiazolyl, dimethylpyridyl, methylquinolyl, dimethylpyrryl, methoxyfuryl, dimethoxypyridyl or difluoropyridyl.

Two adjacent radicals together form an unsaturated, saturated or aromatic, optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles and optionally substituted by one or more oxygen and / or sulfur atoms and / or one or more several substituted or unsubstituted imino groups interrupted ring, it is preferably 1, 3-propylene, 1, 4-butylene, 1, 5-pentylene, 2-oxa-1, 3-propylene, 1-oxa-1, 3- propylene, 2-oxa-1, 3-propylene, 1-oxa-1, 3-propenylene, 3-oxa-1, 5-pentylene, 1-aza-1, 3-propenylene, 1-CrC ₄ -alkyl-1 -azo-1, 3-propenylene, 1,4-buta-1,3-dienylene, 1-aza-1, 4-buta-1,3-dienylene or 2-aza-1,4-buta-1,3 -dienylen.

If the abovementioned radicals contain oxygen and / or sulfur atoms and / or substituted or unsubstituted imino groups, the number of oxygen and / or sulfur atoms and / or imino groups is not restricted. Usually amounts to not more than 5 in the balance, preferably not more than 4, and most preferably not more than 3.

If the abovementioned radicals contain heteroatoms, then there is usually at least one carbon atom between two heteroatoms, preferably at least two carbon atoms.

Particularly preferably, the radicals R ¹ to R ⁹ are each independently

• hydrogen;

• straight-chain or branched, unsubstituted or monosubstituted to hydroxyl, halogen, phenyl, cyano, C ₁ to C ₆ alkoxycarbonyl and / or sulfonic acid-substituted C ₁ to C ₈ -alkyl having in total 1 to 20 carbon atoms, such as, for example, methyl , Ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, 2-methyl-1-propyl (isobutyl), 2-methyl-2-propyl (tert-butyl), 1-pentyl, 2- Pentyl, 3-pentyl,

2-methyl-1-butyl, 3-methyl-1-butyl, 2-methyl-2-butyl, 3-methyl-2-butyl, 2,2-dimethyl-1-propyl, 1-hexyl, 2- Hexyl, 3-hexyl, 2-methyl-1-pentyl, 3-methyl-1-pentyl, 4-methyl-1-pentyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl 2-pentyl, 2-methyl-3-pentyl, 3-methyl-3-pentyl, 2,2-dimethyl-1-butyl, 2,3-dimethyl-1-butyl, 3,3-dimethyl-1-butyl, 2-ethyl-1-butyl, 2,3-dimethyl-2-butyl, 3,3-

Dimethyl-2-butyl, 1-heptyl, 1-octyl, 1-nonyl, 1-decyl, 1-undecyl, 1-dodecyl, 1-tetradecyl, 1-hexadecyl, 1-octadecyl, 2-hydroxyethyl, benzyl, 3 Phenylpropyl, 2-cyanoethyl, 2- (methoxycarbonyl) -ethyl, 2- (ethoxycarbonyl) -ethyl, 2- (n-butoxycarbonyl) -ethyl, trifluoromethyl, difluoromethyl, fluoromethyl, pentafluoroethyl, heptafluoropropyl, heptafluoroisopropyl, nonafluorobutyl, Nonafluorisobutyl,

Undecylfluoropentyl, undecylfluoroisopentyl, 6-hydroxyhexyl and propylsulfonic acid;

Glycols, butylene glycols and their oligomers having 1 to 100 units and a hydrogen or a C 1 to C ₈ alkyl as end group, such as

R ^A O- (CHR ^B -CH ₂ -O) _n -CHR ^B -CH ₂ - or R ^ - (CH ₂ CH ₂ CH ₂ CH ₂ O) _n - CH ₂ CH ₂ CH ₂ CH ₂ O- with R ^A and R ^{B are} preferably hydrogen, methyl or ethyl and n is preferably from 0 to 3, in particular 3-oxabutyl, 3-oxapentyl, 3,6-dioxaheptyl, 3,6-dioxaoctyl, 3,6,9-trioxadecyl, 3.6, 9-trioxaundecyl, 3,6,9,12-tetraoxatridecyl and 3,6,9,12-tetraoxatetradecyl;

• vinyl; and

• N, N-di-C ₁ to C ₆ -alkyl-amino, such as N, N-dimethylamino and N, N-diethylamino. Most preferably, the radicals R ¹ to R ⁹ independently of one another are hydrogen or C 1 - to C ₈ -alkyl, such as, for example, methyl, ethyl, 1-butyl, 1-pentyl, 1-hexyl, 1-heptyl, 1-octyl, for phenyl, for 2-hydroxyethyl, for 2-cyanoethyl, for 2- (methoxycarbonyl) ethyl, for 2- (ethoxycarbonyl) ethyl, for 2- (n-butoxycarbonyl) ethyl, for N, N-dimethylamino, for N, N -Diethylamino, for chlorine and for CH ₃ O- (CH ₂ CH ₂ O) _n - CH ₂ CH ₂ - and CH ₃ CH ₂ O- (CH ₂ CH ₂ O) _n -CH ₂ CH ₂ - with n equal to O. to 3.

Very particularly preferred pyridinium ions (Ia) are those in which

• one of the radicals R ¹ to R ^{5 is} methyl, ethyl or chlorine and the remaining radicals R ¹ to R ^{5 are} hydrogen;

• R ^{3 is} dimethylamino and the remaining radicals R ¹ , R ² , R ⁴ and R ^{5 are} hydrogen;

• all radicals R ¹ to R ^{5 are} hydrogen;

• R ^{2 is} carboxy or carboxamide and the remaining radicals R ¹ , R ² , R ⁴ and R ⁵

Are hydrogen; or

• R ¹ and R ² or R ² and R ^{3 is} 1, 4-buta-1, 3-dienylene and the remaining radicals

R ¹ , R ² , R ⁴ and R ^{5 are} hydrogen;

and in particular those in which

• R ¹ to R ^{5 are} hydrogen; or

• one of the radicals R ¹ to R ^{5 is} methyl or ethyl and the remaining radicals R ¹ to R ^{5 are} hydrogen.

Examples of very particularly preferred pyridinium ions (Ia) which may be mentioned are 1-methylpyridinium, 1-ethylpyridinium, 1- (1-butyl) pyridinium, 1- (1-hexyl) pyridinium, 1- (1-octyl) -pyridinium, 1 (1-Hexyl) pyridinium, 1- (1-octyl) pyridinium, 1- (1-dodecyl) pyridinium, 1- (1-tetradecyl) pyridinium, 1- (1-hexadecyl) pyridinium, 1, 2-dimethylpyridinium, 1-ethyl-2-methylpyridinium, 1- (1-butyl) -2-methylpyridinium, 1- (1-hexyl) -2-methylpyridinium, 1- (1-octyl) -2-methylpyridinium, 1- (1-dodecyl) -2-methylpyridinium, 1- (1-tetradecyl) -2-methylpyridinium, 1- (1-hexadecyl) -2-methylpyridinium, 1-methyl-2-ethylpyridinium, 1, 2-diethylpyridinium, 1- (1-butyl) -2-ethylpyridinium, 1- (1-hexyl) -2-ethylpyridinium, 1- (1-octyl) -2-ethylpyridinium, 1- (1-dodecyl) - 2-ethylpyridinium, 1- (1-tetradecene I) - 2-ethylpyridinium, 1- (1-hexadecyl) -2-ethylpyridinium, 1, 2-dimethyl-5-ethyl-pyridinium, 1, 5-diethyl-2- Methyl-pyridinium, 1- (1-butyl) -2-methyl-3-ethyl-pyridinium, 1- (1-hexyl) -2- methyl-3-ethyl-pyridinium and 1- (1-octyl) -2-methyl-3-ethyl-pyridinium, 1- (1-dodecyl) -2-methyl-3-ethylpyridinium, 1- (1-tetradecyl ) -2-methyl-3-ethyl-pyridinium and 1- (1-hexadecyl) -2-methyl-3-ethyl-pyridinium.

Very particularly preferred pyridazinium ions (Ib) are those in which

• R ¹ to R ^{4 are} hydrogen; or

• one of the radicals R ¹ to R ^{4 is} methyl or ethyl and the remaining radicals R ¹ to R ^{4 are} hydrogen.

Very particularly preferred pyrimidinium ions (Ic) are those in which

• R ^{1 is} hydrogen, methyl or ethyl and R ² to R ^{4 are} independently hydrogen or methyl; or R ^{1 is} hydrogen, methyl or ethyl, R ² and R ^{4 are} methyl and R ^{3 is} hydrogen.

Very particularly preferred pyrazinium ions (Id) are those in which

• R ^{1 is} hydrogen, methyl or ethyl and R ² to R ^{4 are} independent of one another

Are hydrogen or methyl;

• R ^{1 is} hydrogen, methyl or ethyl, R ² and R ^{4 are} methyl and R ^{3 is} hydrogen;

• R ¹ to R ^{4 are} methyl; or • R ¹ to R ^{4 are} methyl.

Very particularly preferred imidazolium ions (Ie) are those in which

R ^{1 is} hydrogen, methyl, ethyl, 1-propyl, 1-butyl, 1-pentyl, 1-hexyl, 1-octyl, 22 -H-hydroxydroxy-oxyethylthioyl, ooddeerr 22-CCyyaannooeeththyl and R ² to R ^{4 are} independently

Are hydrogen, methyl or ethyl.

Very particularly preferred imidazolium ions (Ie) which may be mentioned are 1-methylimidazolium, 1-ethylimidazolium, 1- (1-butyl) -imidazolium, 1- (1-octyl) -imidazolium, 1- (1-dodecyl) -imidazolium, 1- (1-Tetradecyl) -imidazolium, 1- (1-hexadecyl) -imidazolium, 1,3-dimethylimidazolium, 1-ethyl-3-methylimidazolium, 1- (1-butyl) -3-methylimidazolium, 1- (1 Butyl) -3-ethylimidazolium, 1- (1-hexyl) -3-methylimidazolium, 1- (1-hexyl) -3-ethylimidazolium, 1- (1-hexyl) -3-butylimidazolium, 1- (1-octyl) -3-methylimidazolium, 1- (1-octyl) -3-ethylimidazolium, 1- (1-octyl) -3-butylimidazolium, 1- (1-dodecyl) -3-methylimidazolium, 1- (1-dodecyl) -3-ethylimidazolium, 1- (1-dodecyl) -3-butylimidazolium, 1- (1-dodecyl) -3-octylimidazolium, 1- (1-tetradecyl) -3-methylimidazolium, 1 - (1 -trad ecy I) -3- ethylimidazolium, 1- (1-tetradecyl) -3-butylimidazolium, 1- (1-tetradecyl) -3-octylimidazolium, 1- (1-hexadecyl) -3-methylimidazolium, 1- (1-hexadecyl) -3- ethylimidazolium, 1- (1-hexadecyl) -3-butylimidazolium, 1- (1-hexadecyl) -3-octylimidazolium, 1,2-dimethylimidazolium, 1,2,3-trimethylimidazolium, 1-ethyl-2,3- dimethylimidazolium, 1- (1-butyl) -2,3-dimethylimidazolium, 1- (1-hexyl) -2,3-dimethylimidazolium, 1- (1-octyl) -2,3-dimethylimidazolium, 1, 4-dimethylimidazolium, 1, 3,4-trimethylimidazolium, 1, 4-dimethyl-3-ethylimidazolium, 3-butylimidazolium, 1, 4-dimethyl-3-octylimidazolium, 1, 4,5-trimethylimidazolium, 1, 3, 4,5-tetramethylimidazolium, 1, 4,5-trimethyl-3-ethylimidazolium, 1, 4,5-trimethyl-3-butylimidazolium and 1, 4,5-trimethyl-3-octylimidazolium.

Very particularly preferred pyrazolium ions (If), (Ig) or (Ig ') are those in which

• R ^{1 is} hydrogen, methyl or ethyl and R ² to R ^{4 are} independent of one another

Are hydrogen or methyl.

Very particularly preferred pyrazolium ions (Ih) are those in which

• R ¹ to R ^{4 are} independently hydrogen or methyl.

Very particular preference is given to using as 1-pyrazolinium ions (Ii) those in which

• independently of one another R ¹ to R ^{6 are} hydrogen or methyl.

Very particular preference is given to using 2-pyrazolinium ions (Ij) or (Ij ') as those in which

• R ^{1 is} hydrogen, methyl, ethyl or phenyl and R ² to R ^{6 are} independently hydrogen or methyl.

Very particular preference is given to using as 3-pyrazolinium ions (Ik) or (Ik ') those in which

• R ¹ and R ^{2 are} independently hydrogen, methyl, ethyl or phenyl and R ³ to R ^{6 are} independently hydrogen or methyl.

Very particularly preferred imidazolinium ions (II) are those in which • R ¹ and R ^{2 are} independently hydrogen, methyl, ethyl, 1-butyl or phenyl, R ³ and R ^{4 are} independently hydrogen, methyl or ethyl, and R ⁵ and R ^{6 are} independently hydrogen or methyl.

Very particular preference is given to using imidazolinium ions (Im) or (Im ') as those in which

• R ¹ and R ^{2 are} independently hydrogen, methyl or ethyl and R 3 to R 36 are independently hydrogen or methyl.

Very particular preference is given to using imidazolinium ions (In) or (In ') as those in which

• R ¹ to R ^{3 are} independently hydrogen, methyl or ethyl and R ⁴ to R ^{6 are} independently hydrogen or methyl.

Very particular preference is given to using thiazolium ions (lo) or (lo ') and oxazolium ions (Ip) as those in which

• R ^{1 is} hydrogen, methyl, ethyl or phenyl and R ² and R ^{3 are} independently hydrogen or methyl.

Very particular preference is given to using as 1,2,4-triazolium ions (Iq), (Iq ') or (Iq ") those in which

• R ¹ and R ^{2 are} independently hydrogen, methyl, ethyl or phenyl and R ^{3 is} hydrogen, methyl or phenyl.

Very particular preference is given to using as 1,3,3-triazolium ions (Ir), (Ir ') or (Ir ") those in which

• R ^{1 is} hydrogen, methyl or ethyl and R ² and R ^{3 are} independently hydrogen or methyl, or R ² and R ³ together are 1, 4-buta-1, 3-dienylene.

Very particularly preferred pyrrolidinium ions (Is) are those in which

• R ^{1 is} hydrogen, methyl, ethyl or phenyl and R ² to R ^{9 are} independently hydrogen or methyl. Very particular preference is given to imidazolidinium ions (It) as those in which

• R ¹ and R ^{4 are} independently hydrogen, methyl, ethyl or phenyl and R ² and R ³ and R ⁵ to R ^{8 are} independently hydrogen or methyl.

Very particular preference is given to using ammonium ions (Iu) as those in which

• R ¹ to R ^{3 are} independently C ¹ to C ₈ alkyl; or

• R ¹ and R ² together are 1, 5-pentylene or 3-oxa-1, 5-pentylene and R ^{3 is} d-C 18 alkyl, 2-hydroxyethyl or 2-cyanoethyl.

As very particularly preferred ammonium ions (Iu) may be mentioned methyl tri (1-butyl) -ammonium, N, N-dimethylpiperidinium and N, N-dimethylmorpholinium.

Examples of the tertiary amines from which the quaternary ammonium ions of the general formula (Iu) are derived by quaternization with the abovementioned radicals R are diethyl-n-butylamine, diethyl-tert-butylamine, diethyl-n-pentylamine, diethylhexylamine, Diethyloctylamine, diethyl (2-ethylhexyl) amine, di-n-propylbutylamine, di-n-propyl-n-pentylamine, di-n-propylhexylamine, di-n-propyloctylamine, di-n-propyl (2-ethyl - hexyl) -amine, di-isopropylethylamine, di-iso-propyl-n-propylamine, di-isopropyl-butylamine, di-isopropylpentylamine, di-iso-propylhexylamine, di-isopropyloctylamine, di-iso-propyl- (2-ethylhexyl ) -amine, di-n-butylethylamine, di-n-butyl-n-propylamine, di-n-butyl-n-pentylamine, di-n-butylhexylamine, di-n-butyloctylamine, di-n-butyl (2 ethylhexyl) amine, Nn-butylpyrrolidine, N-sec-butylpyrrodidine, N-tert-butylpyrrolidine, Nn-pentylpyrrolidine, N, N-dimethylcyclohexylamine, N, N-diethylcyclohexylamine, N, N-di-n-butylcyclohexylamine, N-n-propylpiperidine, N-isopropylpiperidine, Nn-butylpiper idine, N-sec-butylpiperidine, N-tert-butylpiperidine, Nn-pentylpiperidine, Nn-butylmorpholine, N-sec-butylmorpholine, N-tert-butylmorpholine, Nn-pentylmorpholine, N-benzyl-N-ethylaniline, N-benzyl Nn-propylaniline, N-benzyl-N-isopropylaniline, N-benzyl-Nn-butylaniline, N, N-dimethyl-p-toluidine, N, N-diethyl-p-toluidine, N, N-di- n-butyl-p-toluidine, diethylbenzylamine, di-n-propylbenzylamine, di-n-butylbenzylamine, diethylphenylamine, di-n-propylphenylamine and di-n-butylphenylamine.

Preferred tertiary amines (Iu) are di-isopropylethylamine, diethyl-tert-butylamine, diisopropyl-propylamine, di-n-butyl-n-pentylamine, N, N-di-n-butylcyclohexylamine and tertiary amines of pentyl isomers. Particularly preferred tertiary amines are di-n-butyl-n-pentylamine and tertiary amines of pentyl isomers. Another preferred tertiary amine having three identical residues is triallylamine.

Very particular preference is given to guanidinium ions (IV) as those in which

• R ¹ to R ^{5 are} methyl.

As a very particularly preferred guanidinium ion (Iv) is mentioned N, N, N ', N', N ", N" - hexamethylguanidinium.

Very particular preference is given to using as cholinium ions (Iw) those in which

• R ¹ and R ^{2 are} independently methyl, ethyl, 1-butyl or 1-octyl and R ^{3 is} hydrogen, methyl, ethyl, acetyl, -SO ₂ OH or -PO (OH) ₂ ;

• R ^{1 is} methyl, ethyl, 1-butyl or 1-octyl, R ^{2 is} a -CH ₂ -CH ₂ -OR ⁴ group and R ³ and R ^{4 are} independently hydrogen, methyl, ethyl, acetyl, -SO ₂ OH or -PO (OH) ₂ ; or

• R ^{1 is} a -CH ₂ -CH ₂ -OR ⁴ group, R ^{2 is} a -CH ₂ -CH ₂ -OR ⁵ group and R ³ to R ^{5 are} independently hydrogen, methyl, ethyl, acetyl, -SO ₂ OH or -PO (OH) ₂ are.

Particularly preferred cholinium ions (Iw) are those in which R ^{3 is} selected from hydrogen, methyl, ethyl, acetyl, 5-methoxy-3-oxa-pentyl, 8-methoxy-3,6-dioxo-octyl, 1 1-methoxy 3,6,9-trioxa undecyl, 7-methoxy-4-oxa-heptyl, 11-methoxy-4,8-dioxa undecyl, 15-methoxy-4,8,12-trioxa-pentadecyl, 9-methoxy 5-oxa-nonyl, 14-methoxy-5,10-oxa-tetradecyl, 5-ethoxy-3-oxa-pentyl, 8-ethoxy-3,6-dioxa-octyl, 11-ethoxy-3,6,9 trioxa undecyl, 7-ethoxy-4-oxa-heptyl, 1-ethoxy-4,8-dioxa-undecyl, 15-ethoxy-4,8,12-trioxa-pentadecyl, 9-ethoxy-5-oxa nonyl or 14-ethoxy-5,10-oxa-tetradecyl.

Very particularly preferred as phosphonium ions (Ix) are those in which

R ¹ to R ³ independently of one another are C 1 -C ₈ -alkyl, in particular butyl, isobutyl,

1-hexyl or 1-octyl.

Among the above-mentioned heterocyclic cations, the pyridinium ions, pyrrolidinium ions, pyrazolinium, pyrazolium ions, and the imidazolinium and imidazolium ions are preferable. Furthermore, ammonium ions and cholinium ions are preferred. Particular preference is given to 1-methylpyridinium, 1-ethylpyridinium, 1- (1-butyl) pyridinium, 1- (1-hexyl) pyridinium, 1- (1-octyl) pyridinium, 1- (1-hexyl) -pyridinium, 1- (1-Octyl) -pyridinium, 1- (1-dodecyl) -pyridinium, 1- (1-tetradecyl) -pyridinium, 1- (1-hexadecyl) -pyridinium, 1, 2-dimethylpyridinium, 1- Ethyl 2-methylpyridinium, 1- (1-butyl) -2-methylpyridinium, 1- (1-hexyl) -2-methylpyridinium, 1- (1-octyl) -2-methylpyridinium, 1- (1-dodecyl) - 2-methylpyridinium, 1- (1-tetradecyl) -2-methylpyridinium, 1- (1-hexadecyl) -2-methylpyridinium, 1-methyl-2-ethylpyridinium, 1, 2-diethylpyridinium, 1- (1-butyl) - 2-ethylpyridinium, 1- (1-hexyl) -2-ethylpyridinium, 1- (1-octyl) -2-ethylpyridinium, 1- (1-Dodecyl) -2-ethylpyridinium, 1- (1-Tetradecyl) - 2-ethylpyridinium, 1- (1-hexadecyl) -2-ethyl-pyridinium, 1, 2-dimethyl-5-ethylpyridinium, 1, 5-diethyl-2-methylpyridinium, 1- (1-butyl) - 2-methyl-3-ethylpyridinium, 1- (1-hexyl) -2-methyl-3-ethylpyridinium, 1- (1-octyl) -2-methyl-3-ethyl-pyridinium, 1- (1 -Dodecy 1) (1-Hexadecyl) -2-methyl-3-ethyl-pyridinium, 1- (1-hexadecyl) -2-methyl-3-ethyl-pyridinium , 1-methylimidazolium, 1-ethylimidazolium, 1- (1-butyl) -imidazolium, 1- (1-octyl) -imidazolium, 1- (1-dodecyl) -imidazolium, 1- (1-tetradecyl) -imidazolium, 1 - (1-hexadecyl) imidazolium, 1, 3-dimethylimidazolium, 1-ethyl-3-methylimidazolium, 1- (1-butyl) -3-methylimidazolium, 1- (1-hexyl) -3-methylimidazolium , 1- (1-octyl) -3-methylimidazolium, 1- (1-dodecyl) -3-methylimidazolium, 1- (1-tetradecyl) -3-methylimidazolium, 1- (1-hexadecyl) -3-methylimidazolium , 1, 2-dimethylimidazolium, 1, 2,3-trimethylimidazolium, 1-ethyl-2,3-dimethylimidazolium, 1- (1-butyl) -2,3-dimethylimidazolium, 1- (1-hexyl) -2 , 3-dimethylimidazolium and 1- (1-octyl) -2,3-dimethylimidazolium, 1, 4-dimethylimidazolium, 1, 3,4-trimethylimidazolium, 1, 4-dimethyl-3-ethylimidazolium, 3-Bu tylimidazolium, 1,4-dimethyl-3-octylimidazolium, 1, 4,5-trimethylimidazolium, 1, 3,4,5-tetramethylimidazolium, 1, 4,5-trimethyl-3-ethylimidazolium, 1, 4,5-trimethyl-3-butylimidazolium and 1, 4,5-trimethyl-3-octylimidazolium.

The anion [Y] "^'of the ionic liquid is for example selected from

The group of halides and halogen-containing compounds of the formula:

F, Cl ^" , Br ^" , r, BF ₄ ^" , PF ₆ ^" , Al ₃ Cli ₀ ^" , AIBr ₄ ^" , FeCl ₄ ^" , BCI ₄ ^" , SbF ₆ ^" , AsF ₆ , ^" ZnCl ₃ ^" , SnCl ₃ ^" , CuCl ₂ ^" , CF ₃ SO ₃ ^" , (CF ₃ SO ₂ ) ₂ N ^" , CF ₃ CO ₂ ^" , CCI ₃ CO ₂ ^" , CN ^" , SCN ^" , OCN ^"

• the group of sulfates, sulfites and sulfonates of the general formula: SO ₄ ^{2 "} , HSO ₄ ^" , SO ₃ ^{2 "} , HSO ₃ ^" , ROSO ₃ ^" , R ³ SO ₃ ^" • the group of phosphates of the general formula PO ₄ ^{3 ",} HPO ₄ ^{2 ',} H ₂ PO ^_4", R ³ PO ₄ ^2', HR ³ PO ₄ ^", R ³ R ^b P0 ^_4"

The group of phosphonates and phosphinates of the general formula: R ³ H PO ₃ ^" , R ³ R ^b PO ₂ ^" , R ³ R ^b PO ₃ ^"

The group of phosphites of the general formula: PO ₃ ^{3 "} , HPO ₃ ^2" , H ₂ PO ₃ ^" , R ³ PO ₃ ^2" , R ³ HPO ₃ ^" , R ³ R ^b PO ₃ ^"

The group of phosphonites and phosphinites of the general formula: R ^a R ^b PO ₂ ^" , R ³ HPO ₂ ^" , R ^a R ^b PO ^" , R ³ HPO ^"

The group of carboxylic acids of the general formula: R ³ COO ^"

• the group of borates of the general formula: BO ₃ ^{3 ",} HBO ₃ ^2", H ₂ BO ₃ ^", R ³ R ^b BO ^_3", R ³ HBO ₃ ^", R ³ BO ₃ ^2", B (0R ³ ) (0R ^b ) (0R ^c ) (0R ^d ) ^" , B (HSO ₄ ) ^" , B (R ³ SO ₄ ) ^"

The group of boronates of the general formula: R ³ BO ₂ ^{2 "} , R ³ R ^b B0 ^"

The group of carbonates and carbonic esters of the general formula: HCO ₃ ^" , CO ₃ ^2" , R ³ CO ₃ ^"

The group of silicates and silicic acid esters of the general formula: SiO ₄ ^{4 "} , HSiO ₄ ^3" , H ₂ SiO ₄ ^{2 "} , H ₃ SiO ₄ ^" , R ³ SiO ₄ ^{3 "} , R ³ R ^b Si0 ₄ ^2" , R ³ R ^b R ^c Si0 ₄ ^" , HR ³ SiO ₄ ^2" , H ₂ R ³ SiO ₄ ^" , HR ³ R ^b Si0 ₄ ^"

The group of the alkyl or aryl silane salts of the general formula: R ³ SiO ₃ ^{3 "} , R ³ R ^b Si0 ₂ ^2" , R ³ R ^b R ^c Si0 ^" , R ³ R ^b R ^c Si0 ₃ ^" , R ³ R ^b R ^c Si0 ₂ ^" , R ³ R ^b Si0 ₃ ^2"

The group of the carboxylic imides, bis (sulfonyl) imides and sulfonyl imides of the general formula:

The group of methides of the general formula:

SO ₂ -R ³

R ^b -O ₂ S SO ₂ -R ^C

The group of alkoxides and aryloxides of the general formulas: R ³ O ^" ;

• the group of halometallates of the general formula [M _q Hal _r ] ^{s "} , where M is a metal and Hal is fluorine, chlorine, bromine or iodine, q and r are positive integers indicating the stoichiometry of the complex and s is the whole positive number and indicates the charge of the complex; • the group of sulfides, hydrogen sulfides, polysulfides, hydrogen polysulfides and thiolates of the general formulas: S ² -, HS ^" , [Sv] ² -, [HSv] -, [R ³ S] -, where v is a whole positive number of 2 to 10 is the group of complex metal ions such as Fe (CN) ₆ ^{3 "} , Fe (CN) ₆ ^4" , MnO ₄ ^" , Fe (CO) ₄ ^" .

In this R ^a , R ^b , R ^c and R ^d are each independently hydrogen, C 1 -C ₃₀ -alkyl, optionally interrupted by one or more non-adjacent oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino groups C ₂ -C ₈ alkyl, C ₆ -C ₄ aryl, C ₅ -C ₂ cycloalkyl or a five- to six-membered, oxygen-, nitrogen- and / or sulfur-comprising heterocycle, where two of them together form an unsaturated, form saturated or aromatic, optionally interrupted by one or more oxygen and / or sulfur atoms and / or one or more unsubstituted or substituted imino groups ring, said radicals each additionally by functional groups, aryl, alkyl, aryloxy, alkoxy, halogen, Heteroatoms and / or heterocycles can be substituted.

Therein, optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles Ci-Ci ₈ alkyl, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl , Pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, 2,4,4-trimethylpentyl, decyl, dodecyl, tetradecyl, heptadecyl, octadecyl, 1, 1-dimethylpropyl, 1, 1-dimethylbutyl, 1, 1, 3 , 3-tetramethylbutyl, benzyl, 1-phenylethyl, α, α-dimethylbenzyl, benzhydryl, p-tolylmethyl, 1- (p-butylphenyl) -ethyl, p-chlorobenzyl, 2,4-dichlorobenzyl, p-methoxybenzyl, m-ethoxybenzyl , 2-cyanoethyl, 2-cyanopropyl, 2-methoxycarbonethyl, 2-ethoxycarbonylethyl, 2-butoxycarbonylpropyl, 1, 2-di- (methoxycarbonyl) -ethyl, 2-methoxyethyl, 2-ethoxyethyl, 2-butoxyethyl, diethoxymethyl, diethoxyethyl , 1, 3-dioxolan-2-yl, 1, 3-dioxan-2-yl, 2-methyl-1,3-dioxolan-2-yl, 4-methyl-1,3-dioxolan-2-yl, 2 1-isopropoxyethyl, 2-butoxypropyl, 2-octyloxyethyl, chloromethyl, trichloromethyl, trifluoromethyl, 1 , 1-Dimethyl-2-chloroethyl, 2-methoxy-isopropyl, 2-ethoxyethyl, butylthiomethyl, 2-dodecylthioethyl, 2-phenylthioethyl, 2,2,2-trifluoroethyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 4-hydroxybutyl , 6-hydroxyhexyl, 2-aminoethyl, 2-aminopropyl, 4-aminobutyl, 6-aminohexyl, 2-methylaminoethyl, 2-methylaminopropyl, 3-methylaminopropyl, 4-methylaminobutyl, 6-methylaminohexyl, 2-dimethylaminoethyl, 2 Dimethylaminopropyl, 3-dimethylaminopropyl, 4-dimethylaminobutyl, 6-dimethylaminohexyl, 2-hydroxy-2,2-dimethylethyl, 2-phenoxyethyl, 2-phenoxypropyl, 3-phenoxypropyl, 4-phenoxybutyl, 6-phenoxyhexyl, 2-methoxyethyl , 2-methoxypropyl, 3-methoxypropyl, 4-methoxybutyl, 6-methoxyhexyl, 2-ethoxyethyl, 2-ethoxypropyl, 3-ethoxypropyl, 4-ethoxybutyl or 6-ethoxyhexyl. Optionally C ₂ -C ₈ -alkyl which is interrupted by one or more non-adjacent oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino groups are, for example, 5-hydroxy-3-oxapentyl, 8-hydroxy-3, 6-dioxaoctyl, 1 1-hydroxy-3,6,9-trioxaundecyl, 7-hydroxy-4-oxaheptyl, 1-hydroxy-4,8-dioxaundecyl, 15-hydroxy-4,8,12-trioxapentadecyl, 9- Hydroxy-5-oxa-nonyl, 14-hydroxy-5,10-oxatetradecyl, 5-methoxy-3-oxapentyl, 8-methoxy-3,6-dioxo-octyl, 1-methoxy-3,6,9-trioxaundecyl , 7-methoxy-4-oxaheptyl, 1-methoxy-4,8-dioxa- undecyl, 15-methoxy-4,8,12-trioxapentadecyl, 9-methoxy-5-oxanonyl, 14-methoxy-5,10- oxatetradecyl, 5-ethoxy-3-oxapentyl, 8-ethoxy-3,6-dioxo-octyl, 1-ethoxy-3,6,9-trioxa-undecyl, 7-ethoxy-4-oxaheptyl, 1-ethoxy-4,8- dioxaundecyl, 15-ethoxy-4,8,12-trioxapentadecyl, 9-ethoxy-5-oxanonyl or 14-ethoxy-5,10-oxatetradecyl.

If two radicals form a ring, these radicals can be taken together, for example, as fused building block 1, 3-propylene, 1,4-butylene, 2-oxa-1,3-propylene, 1-oxa-1,3-propylene, 2-oxa 1, 3-propenylene, 1-aza-1, 3-propenylene, 1-dC ₄ -alkyl-1-aza-1, 3-propenylene, 1, 4-buta-1, 3-dienylene, 1-aza 1, 4-buta-1, 3-dienylene or 2-aza-1,4-buta-1,3-dienylene.

The number of non-adjacent oxygen and / or sulfur atoms and / or imino groups is basically not limited, or is automatically limited by the size of the remainder or the ring building block. As a rule, it is not more than 5 in the respective radical, preferably not more than 4 or very particularly preferably not more than 3. Furthermore, at least one, preferably at least two, carbon atoms (e) are generally present between two heteroatoms.

Substituted and unsubstituted imino groups may be, for example, imino, methylimino, iso-propylimino, n-butylimino or tert-butylimino.

The term "functional groups", for example, the following hen to be understood: carboxy, carboxamide, hydroxy, di (Ci-C ₄ alkyl) amino, dC ₄ alkyloxycarbonyl, cyano or C ₄ alkoxy It is Ci. to C ₄ alkyl, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl or tert-butyl.

Optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles C6-C ₄ aryl, for example,

Phenyl, ToIyI, XyIyI, α-naphthyl, β-naphthyl, 4-diphenylyl, chlorophenyl, dichlorophenyl,

Trichlorophenyl, difluorophenyl, methylphenyl, dimethylphenyl, trimethylphenyl, ethylphenyl, diethylphenyl, isopropylphenyl, tert-butylphenyl, dodecylphenyl, methoxyphenyl, dimethoxyphenyl, ethoxyphenyl, hexyloxyphenyl, methylnaphthyl, isopropylnaphthyl, chloronaphthyl, ethoxynaphthyl, 2,6 -Dimethylphenyl, 2,4,6-

Trimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl, 4-bromophenyl, 2- or 4- Nitrophenyl, 2,4- or 2,6-dinitrophenyl, 4-dimethylaminophenyl, 4-acetylphenyl, methoxyethylphenyl or ethoxymethylphenyl.

May optionally be substituted by functional groups, aryl, alkyl, aryloxy, halogen, Heteroato- me and / or heterocyclic C ₅ -C ₂ -cycloalkyl are for example cyclopentyl, cyclohexyl, cyclooctyl, cyclododecyl, methylcyclopentyl, dimethylcyclopentyl,

Methylcyclohexyl, dimethylcyclohexyl, diethylcyclohexyl, butylcyclohexyl, methoxycyclohexyl, dimethoxycyclohexyl, diethoxycyclohexyl, butylthiocyclohexyl, chlorocyclohexyl, dichlorocyclohexyl, dichlorocyclopentyl and a saturated or unsaturated bicyclic system such as norbornyl or norbornenyl.

A five- to six-membered, oxygen, nitrogen and / or sulfur-containing heterocycle is, for example, furyl, thiophenyl, pyryl, pyridyl, indolyl, benzoxazolyl, dioxolyl, dioxy, benzimidazolyl, benzothiazolyl, dimethylpyridyl, methylquinolyl, dimethylpyryl, methoxifuryl , Dimethoxypyridyl, difluoropyridyl, methylthiophenyl, isopropylthiophenyl or tert-butylthiophenyl.

Preferred anions are selected from the group of halides and halogen-containing compounds, the group of carboxylic acids, the group of sulfates, sulfites and sulfonates and the group of phosphates.

Preferred anions are chloride, bromide, iodide, SCN ^" , OCN ^" , CN ^" , acetate, C _r C ₄ alkyl sulfates, R ^a -COO ^" , R ³ SO ₃ ^" , R ^a R ^b PO ₄ ^" , methanesulfonates, Tosylate, Ci-C ₄ Dialkylphospha- te, hydrogen sulfate or tetrachloroaluminate.

Imidazolium ions (Ie), imidazolinium ions (Im) or (Im '), pyrrolidinium ions (Is), ammonium ions (Iu) and cholinium ions (Iw) are particularly preferred as cations. Of these, imidazolium ions (Ie) and imidazolinium ions (Im) or (Im ') are particularly preferred, and in particular, imidazolium ions (Ie) are preferable.

Very particularly preferred as cations are dialkylimidazolium cations in which the two alkyl groups, identical or different, branched or unbranched, may be substituted or unsubstituted by one or more phenyl groups and have 1 to 6 carbon atoms. Preferred of these are benzylmethylimidazolium, hexymethylimidazolium, butylmethylimidazolium, ethylmethylimidazolium. Most preferably, the cation is ethylmethylimidazolium.

Preferred anions are halides. Very particularly preferred as the anion is chloride. When an ionic liquid is used as solvent, in particular ethylmethylimidazolium chloride is preferred.

In addition to the use of an ionic liquid, it is alternatively possible to use a mixture of two or more ionic liquids. Preferably, however, only one ionic liquid is used.

In a preferred embodiment, an additive is added to the first metal component. By adding an additive, for example, the redox potential of the metal components involved and / or the kinetics of the redox reaction can be influenced.

To influence the redox potential and / or the kinetics of the direct redox reaction, complexing additives are preferably used. Suitable complexing additives are all complexing agents known to the person skilled in the art. Such complexing agents are usually ionic ligands or non-ionic ligands. Suitable nonionic ligands are, for example, ammonia, triphenylphosphine, carbon monoxide, benzene, butadiene, ethyleneamine, ethylenediaminetetraacetic acid (EDTA), tartrates, porphyrin ring systems such as chlorophyll or hemoglobin or carbohydrates. Suitable ionic ligands are, for example, CN ^" , SCN ^" , OH ^" , Cl ^" , F ^" , S ^2" .

The addition of additives is also preferred if the less noble first metal component in the solvent is rendered inert by the formation of an oxide layer and a suitable additive can prevent the inertization.

The additive, by which the inertization of the first metal component is prevented, may for example be added to the first metal component or, alternatively, be contained as an additive in the solvent.

When using the non-metallic carrier substrate with the thin, porous metal layer applied thereto in a fuel cell, it is further preferred if an ionomer is applied during and / or after the replacement of the first metal component by the metal to be applied to the carrier substrate.

By applying the ionomer to the metal to be applied, the ionic coupling of regions of the catalyst layer which are not in direct contact with the membrane is improved. As ionomers in this context are meant ionically conductive polymers.

The application of the ionomers can take place during the replacement of the first metal component by the metal to be applied to the carrier substrate. In this case it is preferred if the ionomer is likewise contained in the solvent containing the metal to be applied to the carrier substrate. This procedure further simplifies the process. In addition, the ionomer can also change the concentration of the reactants involved in the redox reaction in the solvent and favorably influence the redox potentials.

When the ionomer is applied after replacement of the first metal component by the metal to be applied to the carrier substrate, any suitable method by which an ionomer can be applied is suitable. The application of the ionomer can take place, for example, by printing, spraying, knife coating, rolling, brushing or brushing. For this purpose, the ionomer is usually dissolved in a suitable solvent. Suitable solvents for the ionomer are, for example, water, mono- and polyhydric alcohols, nitrogen-containing polar solvents, glycols, glycol ether alcohols or glycol ethers. Particularly suitable are, for example, propylene glycol, dipropylene glycol, glycerol, ethylene glycol, hexylene glycol, dimethylacetamide, N-methylpyrrolidone or mixtures thereof.

Suitable ionomers, which can also be applied to the metal to be applied to the carrier substrate, are known to the person skilled in the art and are described, for example, in WO 03/054991.

Preferably, at least one ionomer is used which has sulfonic acid, carboxylic acid and / or phosphonic acid groups. Suitable ionomers containing sulfonic acid, carboxylic acid and / or phosphonic acid groups are known to the person skilled in the art. Sulfonic acid, carboxylic acid and / or phosphonic acid groups are to be understood as meaning groups of the formulas -SO ₃ S, -COOX and -PO ₃ X ₂ , where XH ⁺ , NH ₄ ⁺ , NH ₃ R ⁺ , NH ₂ R ₃ ⁺ , NHR ₃ ⁺ or NR ₄ ⁺ means. In this formula, R is an arbitrary radical, preferably a C 1 -C 5 -alkyl, preferably a C 1 -C ₄ -alkyl, which is optionally substituted in such a way that protons can be released under conditions which are usually present for fuel cells.

Particularly preferred ionomers are sulfonic acid-containing polymers selected from the group consisting of perfluorinated sulfonated hydrocarbons, for example Nafion® from EI Dupont De Nemours and Company, sulfonated aromatic polymers, for example sulfonated polyaryl ether ketones such as polyether ether ketones (sPEEK), sulfonated polyether ketones (sPEK), sulfonated polyether ketone ketones (sPEKK), sulfonated polyether ether ketone ketones (sPEEKK), sulfonated polyarylene ether sulfones, sulfonated polybenzobisbenzazoles, sulfonated polybenzothiazoles, sulfonated polybenzimidazoles, sulfonated polyamides, sulfonated polyetherimides, sulfonated polyphenylene oxides, for example poly-2,6-dimethyl-1, 4- phenylene oxides, sulfonated polyphenylene sulfides, sulfonated phenolic Formaldehyde resins, which may be linear or branched, sulfonated polystyrenes, which may be linear or branched, sulfonated polyphenylenes and other sulfonated aromatic polymers.

The sulfonated aromatic polymers may be partially or completely fluorinated.

Further suitable sulfonated polymers include polyvinylsulfonic acids, copolymers composed of acrylonitrile and 2-acrylamido-2-methyl-1-propanesulfonic acids, acrylonitrile and vinylsulfonic acids, acrylonitrile and styrenesulfonic acids, acrylonitrile and methacryloxyethoxyoxypropanesulfonic acids, acrylonitrile and methacryloxyethyleneoxytetrafluoroethylene sulfonic acids, etc. The polymers can in turn partially or fully fluorinated. Other groups of suitable sulfonated polymers include sulfonated polyphosphazenes such as poly (sulfophenoxy) phosphazenes or poly (sulfoethoxy) phosphazenes. The polyphosphazene polymers may be partially or fully fluorinated. Sulfonated polyphenylsiloxanes and copolymers thereof, poly (sulfoalkoxy) phosphazenes, poly (sulfotetrafluoroethoxypropoxy) siloxanes are also suitable.

Examples

Comparative example

A gas diffusion electrode is prepared by screen-printing an ink containing a platinum-supported platinum catalyst on a gas diffusion layer (SGL 25DC of SGL Carbon). The supported on carbon platinum catalyst contains 30 wt .-% platinum on a carbon black Vulcan XC72. By applying the ink, a platinum loading of about 1.0 mg / cm ^{2 is} obtained. The gas diffusion electrode obtained by printing was dried at 50 ^° C. and then laminated in a laminator at 100 ^° C.

From the gas diffusion electrode thus produced, the electrochemical activity was examined by oxygen reduction in half a cell. Half of the cell was filled with 85% phosphoric acid. The gas diffusion electrode was connected as a working electrode and a platinum wire as a counter electrode. The reference electrode used was a reversible hydrogen electrode (RHE). As feed, pure oxygen was added. Potentiostatic measurements of oxygen reduction at 800 mV versus the reference electrode were performed at 140 ° C. The activity of the oxygen reduction is 17.4 mA / mgPt.

example 1 A gas diffusion layer (SGL 25DC from SGL Carbon) is used to produce a gas diffusion electrode. An aluminum layer is applied to the gas diffusion layer by a PVD process. The aluminum layer produced in this way has a layer thickness of 500 nm.

The aluminum coated gas diffusion layer is dipped in a solution containing platinum. The platinum-containing solution is prepared by dissolving H ₂ PtClO in an ionic liquid containing 1.0 mol of ethylmethylimidazole and 1.5 mol of AlCl ₃ . The aluminum-coated gas distribution layer remains 2 hours at 100 ⁰ C in the solution. During this time, the aluminum is oxidized and platinum in the form of Pt (IV) is reduced. Thereafter, the black, platinum-coated gas distribution layer is rinsed in acetonitrile and water. This is followed by drying in air. A Nafion® solution is sprayed on the dried, platinum-coated gas distribution layer. The ionomer charge is 0.2 mg / cm ² .

The gas diffusion electrode thus prepared was examined by X-ray diffractometry. It was found that the platinum particles deposited on the gas diffusion layer have a size of about 5 to 7 nm. Scanning electron microscope and transmission electron microscope investigations showed that the porous platinum layer was formed with some agglomerates on the surface of the gas diffusion layer and individual platinum particles were dispersed in the gas diffusion layer. The thickness of the platinum layer is less than 2 μm. The measured loading of platinum was 0.8 mg / cm ² .

The process according to the invention thus makes it possible to produce a much thinner catalyst layer. The catalyst layer has a platinum loading that is 20% lower than that of the catalyst layer known in the art. The measured activity of oxygen reduction is 16.7 mA / mg Pt. It turns out that the lower platinum loading leads only to a minimal reduction in the activity of the catalyst layer. Thus, a thickness of the catalyst layer reduced by more than 96% does not lead to a noticeable loss of function of the electrode.

Example 2

A gas diffusion electrode according to Example 1 is produced, but instead of the gas diffusion layer SGL 25DC, a gas diffusion layer H2315 1X11 C45 from Freudenberg AG is used. The thickness of the applied aluminum layer is 200 nm and the aluminum-coated gas diffusion layer is immersed for 20 min at a temperature of 100 ⁰ C in a platinum solution with a platinum content of 0.075 wt .-% platinum. It forms a platinum layer with a layer thickness from 700 nm and the platinum particles contained therein have a size of 3.7 nm. The PPllaattiinnbbeellaadduunngg bbeet carries 0.42 mg / cm ² and the measured oxygen activity in the half cell is 35 mA / mg Pt.

Claims

claims A method of applying a metal to a carrier substrate to produce a thin, porous layer, comprising the steps of: (a) applying a first metal component to the carrier substrate, wherein the first metal component is less noble than the metal to be applied, (b) replacing the first metal component applied in step (a) with the metal to be applied to the carrier substrate by means of a redox Reaction. 2. The method according to claim 1, characterized in that the first metal component is a metal of the 3rd to 5th main group or a metal of the subgroup elements of the first period of the periodic table of the elements. 3. The method according to claim 1 or 2, characterized in that the first metal component is selected from the group consisting of aluminum, iron, cobalt, nickel, copper and zinc. 4. The method according to any one of claims 1 to 3, characterized in that the metal to be applied to the carrier metal is catalytically active. 5. The method according to any one of claims 1 to 4, characterized in that the metal to be applied to the carrier substrate is selected from the group consisting of platinum, palladium, ruthenium and gold. 6. The method according to any one of claims 1 to 5, characterized in that the non-metallic carrier substrate is carbon, a polymer or a ceramic. 7. The method according to any one of claims 1 to 6, characterized in that the non-metallic carrier material is a gas distributor layer or a membrane, as it is used in fuel cells. 8. The method according to any one of claims 1 to 7, characterized in that the first metal component is applied from the vapor phase to the non-metallic carrier substrate. 9. The method according to any one of claims 1 to 8, characterized in that the first metal component is applied by a PVD method, CVD method or by sputtering on the non-metallic carrier substrate. 10. The method according to any one of claims 1 to 9, characterized in that the redox reaction in which the first metal component is replaced by the metal to be applied to the non-metallic support substrate, is carried out in a solvent. 1 1. A method according to any one of claims 1 to 10, characterized in that the solvent is an ionic liquid. 12. The method according to any one of claims 1 to 1 1, characterized in that the solvent is ethyl-methyl-imidazolium chloride. 13. The method according to any one of claims 1 to 12, characterized in that the first metal component, an additive is added. 14. The method according to any one of claims 1 to 13, characterized in that the additive is a complexing agent. 15. The method according to Ansprurch 14, characterized in that the complexing agent is an ionic ligand or a non-ionic ligand. 16. The method according to any one of claims 1 to 15, characterized in that an ionomer is applied during and / or after the replacement of the first metal component by the metal to be applied to the carrier substrate metal.