Method for forming a catalyst for electrocatalysis, catalyst and device for electrocatalysis

Abstract

The invention relates to a method 1, 10 for forming a catalyst 5 for electrocatalysis. The method 1, 10 comprises bringing into contact a catalyst starting material 17 arranged on an electrode substrate 16 with an oxidizing agent composition 18 s1 and at least partially oxidizing the catalyst starting material 17 by means of the oxidizing agent composition 18. In addition, the invention relates to a catalyst 5 and a device 100 for electrocatalysis as well as the use of a catalyst 5.

Description

[0001] The invention relates to a method for forming a catalyst for electrocatalysis, a catalyst and a device for electrocatalysis and the use of a catalyst.

[0002] The electrochemical reduction of CO2 and / or CO is a technology to convert CO2 and / or CO by electrolysis into hydrocarbons such as methane, ethane, ethene, ethyne and / or oxygenates such as alcohols, aldehydes and / or acids.

[0003] For this purpose, an electrolysis device can be used, which is equipped with a gas diffusion electrode as the working electrode for the direct, gaseous supply of CO2 or CO. A gas diffusion electrode is permeable to gas, but not to the liquid electrolyte. At the same time, the working electrode is conductive and equipped with a solid catalyst, allowing electrochemical CO2 or CO reduction to occur at high current densities at a three-phase boundary between the catalyst, the CO2 or CO, and the electrolyte.

[0004] Regarding product selectivity and stability of the electrolysis process, the catalyst is the key component. Highly specialized nanomaterials are used as catalysts. However, these have several disadvantages. First, they are generally complex and can only be produced in small quantities, making them very expensive. Second, nanomaterials generally suffer from poor storage stability. Over time, the material can agglomerate into larger particles or oxidize. This means that the age of a material batch can have a direct impact on the electrolysis process, for example, its product distribution and stability, which is detrimental to the reliability of the technology.

[0005] To the authors' knowledge, this problem has been addressed little to date. Since electrochemical CO2 reduction is currently the subject of research but not yet in industrial use, only a few studies address the problem of catalyst stability in electrocatalysis, which is a low-temperature process with an operating temperature typically below 100°C.

[0006] On a laboratory scale, catalyst materials are often produced in small batches. Storage times are short, so aging is not a problem. This approach is not economical for future application on an industrial scale. Studies are known that rely on generating catalyst structures in situ, i.e., in the electrolysis cell, using electrochemical methods. As far as the inventors of the present invention are aware, however, these processes are limited to the use of cost-intensive materials such as precious metals, nanomaterials, etc. Furthermore, only CO is treated as the target product, not higher-value hydrocarbons such as ethylene. Furthermore, gas diffusion electrodes are not used, but rather conventional metal foils as substrates.

[0007] Furthermore, it is known from J. Zhang, W. Luo, A. Züttel, J. Mater. Chem. A, 7, 26285-26292 (2019), doi: 10.1039 / c9ta06736a that CuO, especially in the form of nanoneedles, is suitable as a catalyst for the reduction of CO2 to hydrocarbons. This publication describes the production of a gas diffusion electrode with a copper-based catalyst. In a first process step, a copper mesh is wet-chemically oxidized and, in a second process step, coated with a PTFE dispersion and dried. In a third process step, another dispersion containing PTFE and carbon black is coated to form the gas diffusion layer. In a fourth process step, the electrode is annealed at 350°C for 1 h. The disadvantage of this process is the complex four-step process. In addition, the already mentioned problem of the storage stability of the finished gas diffusion electrode also exists here.

[0008] Against this background, it is an object of the invention to provide a method for forming a catalyst for electrocatalysis with which the problems explained above can be at least partially eliminated.

[0009] This problem is solved by the subject matter of the independent claims. The dependent claims relate to embodiments of these inventive solutions.

[0010] A first aspect of the invention relates to a method for forming a catalyst for electrocatalysis.

[0011] Electrocatalysis is a heterogeneous catalysis that lowers the activation energy of electrochemical reactions at an electrode surface. It allows for high currents at low overpotentials in electrochemical processes. For example, the electrolysis of CO2 and / or CO can be carried out electrocatalyzed. Therefore, a catalyst formed according to the proposed process can be used, for example, in or for the electrolysis of CO2 and / or CO.

[0012] Electrocatalysis is a low-temperature process, meaning it is carried out at temperatures below 100 °C. Therefore, suitable catalysts for electrocatalysis must be catalytically active at temperatures below 100 °C. In this respect, they differ from catalysts for thermocatalysis, which takes place at temperatures above 100 °C, e.g., at temperatures in the range between 250 °C and 650 °C. Furthermore, catalysts for electrocatalysis are electrically conductive or can be connected or bonded in a conductive manner.

[0013] Forming a catalyst means producing a ready-to-use catalyst, i.e., a catalyst that is already activated. The proposed process can be used for the initial formation of a new catalyst, but also for the reactivation of a previously existing catalyst that has been at least partially deactivated over time due to previous catalytic processes, e.g., through reduction, agglomeration, etc., of the catalyst material, and therefore requires reactivation.

[0014] Accordingly, the electrode substrate can be a component of an electrode, such as a support layer or a hydrophobic layer. Together with a non-oxidized sublayer of the catalyst starting material and / or a separate collector layer, the electrode substrate forms an electrode.

[0015] The proposed method provides that a catalyst starting material arranged on an electrode substrate is brought into contact with an oxidizing agent composition and at least partially oxidized, and / or that organic deposits on the catalyst starting material are removed. The oxidation leads to the formation of the catalyst, i.e., the catalyst starting material is converted into an activated catalyst by oxidation, thus forming the catalyst. The duration of the oxidation can be between 5 minutes and 5 hours, preferably between 20 minutes and 1 hour, depending, for example, on the strength of the oxidizing agent and the temperature.

[0016] The oxidant composition can then be removed, e.g., by washing with water and / or a solvent, e.g., ethanol, thereby preventing any influence of the oxidant composition on the electrocatalysis.

[0017] The oxidizing agent composition can, in particular, be an aqueous composition, e.g., an aqueous solution of an oxidizing agent, possibly with additives, e.g., for pH adjustment. In this respect, the oxidation to be carried out can be a wet-chemical oxidation.

[0018] Oxidation of the catalyst starting material can be accompanied by structuring in the nanometer range, which can contribute to high catalytic activity, partly due to the increased surface area. For example, nanoparticles, nanoneedles, etc., can be formed.

[0019] In general, it is possible that only a portion of the catalyst starting material is oxidized, e.g., in near-surface areas where direct contact with the oxidizing agent composition is possible. For example, if a metallic catalyst starting material is used, a portion of the metallic catalyst starting material can be oxidized, resulting in two sublayers forming within the original layer of catalyst starting material: a sublayer containing unoxidized metallic catalyst starting material and an overlying sublayer containing oxidized catalyst starting material. The sublayer containing unoxidized metallic catalyst starting material can be used, for example, as a collector layer of the electrode, while the sublayer containing oxidized catalyst starting material forms the catalyst.

[0020] The process is characterized by the possibility of in situ activation of the catalyst starting material, i.e. a catalyst starting material arranged on the electrode substrate, whereby the catalyst can be formed directly at the site of use. This eliminates the problem of the insufficient storage stability of the activated catalyst material, since the formation of the catalyst can take place temporally and spatially directly at the site of use for electrocatalysis. Furthermore, the proposed process comprises only a few process steps, so that it can be carried out with little expenditure of time and equipment. For example, annealing at elevated temperatures, e.g., a temperature above 100 °C, can be omitted, i.e. the process can be carried out without annealing at a temperature above 100 °C.The in situ formation of the catalyst also ensures increased occupational safety, as, for example, no particulate nanomaterials need to be stored and transported.

[0021] Preferably, the formed catalyst has a large surface area with atomic-scale roughness that is readily wettable by water.

[0022] According to various embodiments, the method may comprise coating the electrode substrate with the catalyst starting material.

[0023] Before contacting the catalyst starting material with the oxidant composition, the catalyst starting material can be applied to the electrode substrate, e.g., a support layer or a hydrophobic layer, to obtain the catalyst material arranged on the electrode substrate. This corresponds to a process step in the initial production of a catalyst-coated electrode. Due to the generally better handling and higher storage stability of the catalyst starting material compared to the activated catalyst material of the catalyst, coating the electrode substrate with the catalyst starting material is simpler and safer than coating or otherwise arranging an activated catalyst material on an electrode substrate.

[0024] The coating of the electrode substrate can preferably be carried out using a PVD process, e.g., by thermal evaporation or sputtering. Using these processes, a particularly uniform or homogeneous layer of the catalyst starting material, e.g., with respect to the layer thickness, chemical composition, and / or morphology of the layer, can be deposited on the electrode substrate, which can contribute to an increase in the service life of the electrode and improved stability of the electrocatalysis carried out with the electrode.

[0025] According to further embodiments, the process may comprise applying a binder material to the oxidized catalyst starting material, which may have been purified from residues of the oxidizing agent composition.

[0026] The binder material may, for example, be a resin or a polymer. Preferably, the binder material may be an anion- or cation-conducting ionomer, e.g., a polytetrafluoroethylene-based ionomer such as a sulfonated tetrafluoroethylene polymer, for example, Nafion. ® , or ionomers with imidazolium ligands, for example Sustainion ® ·

[0027] The binder material can be applied using a dipping or spraying process, squeegee printing, screen printing or a roll-to-roll process.

[0028] By applying the binder material, the oxidized or activated catalyst starting material can be better fixed to the electrode surface, so that the service life of the electrode can be increased.

[0029] According to further embodiments, the catalyst starting material can be an at least partially deactivated catalyst.

[0030] In other words, the proposed method can be used to reactivate an at least partially deactivated catalyst. This can either restore the rough surface structure by oxidizing the catalyst starting material or remove organic deposits that impair catalysis by oxidation. Catalysts often lose their electrocatalytic activity completely or partially during prolonged use, e.g., in electrolysis, e.g., due to degradation of the nanostructured surface. In an electrolyzer, e.g., for converting CO2 into ethylene, after a certain period of operation, e.g.,After a few weeks to months, operation can be briefly interrupted, and the nanostructure of the catalyst surface can be regenerated using the described (wet chemical) oxidation process with the oxidant composition during a maintenance phase, enabling further operating phases with high efficiency. This process can be repeated cyclically, e.g., according to a predefined time schedule or depending on the product yield, which can be analyzed, for example, using the Faradaic efficiency for one or more desired electrolysis products.

[0031] The Faraday efficiency is understood here as the ratio between the part of the electrolysis current, i.e. the electrons released by the cathode, which is used for the production of a specific electrolysis product and the electrolysis current which is used for other electrolysis products.

[0032] Thus, the process offers the possibility of extending the overall service life of a catalyst-coated electrode in electrocatalysis in a simple, safe and cost-effective manner and of carrying out electrocatalysis over a long period of time with high efficiency.

[0033] According to various embodiments, the electrode substrate can be a gas diffusion electrode.

[0034] Such a gas diffusion electrode can be used, for example, as a working electrode, e.g., as a cathode in the electrolysis of CO2 and / or CO. The catalyst starting material can be arranged on a surface of a substrate of the gas diffusion electrode, e.g., on a surface of a support layer or hydrophobic layer.

[0035] A gas diffusion electrode advantageously enables a direct supply of gaseous reactants to be electrocatalyzed. The desired electrocatalysis can thus be carried out continuously and with high efficiency in a simple manner.

[0036] According to various embodiments, the catalyst starting material may comprise at least one material selected from a group comprising copper, copper-containing compounds, silver, silver-containing compounds, gold, gold-containing compounds, lead, lead-containing compounds, zinc, zinc-containing compounds, tin and tin-containing compounds.

[0037] Compounds containing copper, silver, gold, lead, zinc, or tin include, for example, copper, silver, gold, lead, zinc, or tin-containing oxides or alloys with other metals, or alloys of the aforementioned metals with each other and / or alloys with gold, ruthenium, and / or non-precious metals. Of course, the catalyst starting material can contain several of the aforementioned materials.

[0038] The catalyst starting material can preferably comprise copper, so that a copper-containing catalyst can be formed. Copper-containing catalysts have proven particularly efficient for electrocatalysis, particularly in the electrocatalytic conversion of CO2 and / or CO to high-quality hydrocarbons and / or oxygenates, because such a catalyst is capable of forming C–C bonds to a significant extent.

[0039] More preferably, the catalyst starting material can comprise or consist of metallic copper. Metallic copper is characterized by high electrical conductivity, so that, for example, application by sputtering or vapor deposition onto the electrode substrate using conventional sputtering and vapor deposition processes is possible. In addition, a catalyst starting material with or made of metallic copper can simultaneously be used as the collector layer of the electrode. This means that a lower partial layer with or made of metallic copper, i.e. arranged on the electrode substrate, can remain and form the collector layer, while an upper partial layer arranged thereabove can be oxidized to the catalyst using the oxidizing agent composition.

[0040] According to further embodiments, the oxidizing agent composition may comprise at least one composition selected from a group comprising an aqueous solution of ammonium peroxodisulfate and sodium hydroxide, an aqueous hydrogen peroxide solution, an aqueous perchlorate solution, an aqueous nitric acid solution and an aqueous sulfuric acid solution.

[0041] Of course, the oxidizing agent composition may comprise several of the above-mentioned compositions.

[0042] The compositions mentioned are capable, particularly in combination with a copper-containing catalyst starting material, of causing oxidation with the formation of nanostructures, e.g. nanoneedles, which are particularly well suited for electrocatalysis.

[0043] According to further embodiments, the oxidation of the catalyst starting material can be carried out without applying an electrical potential.

[0044] Compared to processes that induce oxidation by applying an electrical potential, the proposed process involves oxidation using the oxidant composition, particularly wet-chemical oxidation. Such oxidation is more controllable and can lead to a structure exhibiting higher catalytic activity. It can be performed at an early stage of production, when the electrical connections to the gas diffusion electrode are not yet present. Furthermore, oxidation using the oxidant composition can purify the catalyst material, as any organic surface contaminants that could lead to reduced activity are removed through oxidation.

[0045] A further aspect of the invention relates to a catalyst for electrocatalysis which is obtainable by means of one of the processes described above.

[0046] Therefore, the above explanations for these processes also serve to describe the proposed catalyst. The advantages of the process are correspondingly associated with the proposed catalyst.

[0047] Such a catalyst is characterized by its nanostructuring, e.g. in the form of nanoneedles, which contribute to improved selectivity of catalysis.

[0048] A further aspect of the invention relates to the use of a catalyst which has been formed according to one of the processes described above or is obtainable by means of such a process for electrocatalysis.

[0049] Therefore, the above explanations of these methods also serve to describe the proposed use. The advantages of the method are correspondingly linked to the proposed use.

[0050] Electrocatalysis can be carried out in particular during the electrolysis of CO2 and / or CO.

[0051] A further aspect of the invention relates to an electrocatalysis device comprising a catalyst formed according to one of the methods described above or a catalyst obtainable by means of such a method.

[0052] Therefore, the above explanations for these methods also serve to describe the proposed device. The advantages of the method are correspondingly associated with the proposed device.

[0053] The electrolysis device may preferably comprise a gas diffusion electrode provided with the formed catalyst. In other words, the catalyst may be formed on a gas diffusion electrode.

[0054] The device can be designed in particular for the electrolysis of CO2 and / or CO, ie it can be an electrolysis device.

[0055] The above-described properties, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understood in connection with the following description of the embodiments, which are explained in more detail in connection with the drawings, in which figures show the following: Fig. 1 a flow chart of an exemplary method; Fig. 2A-C a schematic representation of the fabrication of an exemplary gas diffusion electrode with catalyst; Fig. 3 is a schematic representation of an exemplary electrolysis device; Fig. 4 a representation of the Faraday efficiency and partial current density curves for products of a CO2 electrolysis using the gas diffusion electrode according to Fig. 2C for 20 hours at a constant potential of -1.6 V vs. Ag / AgCl (3 M); and Fig. 5 a flow chart of another exemplary method.

[0056] Referring to Fig. 1, an exemplary method 1 for forming a catalyst 5 for electrocatalysis is explained below. Here, the catalyst 5 is formed on a gas diffusion electrode 23. Method 1 relates to the initial production of a catalyst 5. Method 1 provides for the cost-effective production of a highly functional, nanostructured catalyst layer only when needed by subjecting conventional copper layers to controlled oxidation using a wet-chemical process. Fig. 2 shows the associated gas diffusion electrode 23 ( Fig. 2 below) as well as intermediate steps in their production.

[0057] After starting process 1, in process step S0, an electrode substrate 16 is coated with a catalyst starting material 16. In the exemplary embodiment, the electrode substrate 16 is a carrier layer 20, on whose surface a microporous, hydrophobic layer 21 is arranged. The carrier layer 20 is mechanically stable and can comprise fibers, for example in the form of a fiber layup, woven fabric, knitted fabric, or knitted fabric. Both the carrier layer 20 and the hydrophobic layer 21 are porous to enable the supply of gaseous reactants and the removal of gaseous products through the layers 20, 21 when the gas diffusion electrode 23 is used.

[0058] In process step S0, the surface of the hydrophobic layer 21 is coated with the catalyst starting material 17 by thermal evaporation. In the exemplary embodiment, inexpensive conventional copper granulate serves as the raw material for the thermal evaporation, so that a metallic copper layer is formed as the catalyst starting material 17. Fig. 2A shows the corresponding state after completion of process step S0, wherein the catalyst starting material 17 is arranged on the electrode substrate 16.

[0059] It should be noted that the hydrophobic layer 21 is only optionally present to prevent the penetration of the liquid aqueous electrolyte when using the gas diffusion electrode 23. In other words, the catalyst starting material 17 can, for example, also be deposited directly onto the carrier layer 20. Furthermore, other catalyst starting materials 17 can of course also be used to coat the electrode substrate 16.

[0060] In the subsequent process step S1, the catalyst starting material 17 arranged on the electrode substrate 16 is briefly brought into contact with an oxidizing agent composition 18, e.g., immersed, for a period of time between 20 minutes and 1 hour, for example for approximately 45 minutes. Fig. In Figure 2, this is represented by a block arrow labeled "+18." In process step S3, the catalyst starting material 17 is partially oxidized by the oxidizing agent composition 18. No electrical potential is applied.

[0061] In the exemplary embodiment, an aqueous solution of ammonium peroxodisulfate and sodium hydroxide is used as the oxidizing agent composition 18.

[0062] By partially oxidizing the catalyst starting material 17, two sublayers are obtained. A lower, first sublayer, arranged directly on the hydrophobic layer 21, remains in its original, non-oxidized state, i.e., as a metallic copper layer, due to insufficient contact with the oxidizing agent composition 18. This sublayer forms the electrically conductive collector layer 22 of the gas diffusion electrode 23. The collector layer 22 serves the purpose of enabling good electrical conductivity in the plane, so that the gas diffusion electrode 23 can be contacted from the edge.

[0063] A second upper sublayer consists of oxidized catalyst starting material 17 and forms the catalyst 5. In the exemplary embodiment, nanoneedles of copper (II) oxide (CuO) were formed by treating the catalyst starting material 17 with the oxidizing agent composition 18, which are particularly well suited as catalyst 5 for the reduction of CO2 to hydrocarbons by electrolysis. Fig. 2B shows the corresponding state after completion of process step S2

[0064] In process step S3, the oxidizing agent composition 18 is removed by cleaning with water or a solvent and washing out residues of the oxidizing agent composition 18 (in Fig. 2 not shown).

[0065] Optionally, process 1 can be continued with process step S4, in which a binder material 19 is applied to the oxidized catalyst starting material 17, i.e. the formed catalyst 5. In the exemplary embodiment, a perfluorinated sulfonic acid polymer (Nafion ® ) is used as a binder material 19. In Fig. 2, this is represented by a block arrow labeled "+19". The copper(II) oxide nanoparticles are fixed to the collector layer 22 by means of the binder material 19, so that the resulting gas diffusion electrode 23 ( Fig. 2C) is immediately ready for use and can be used, for example, for electrocatalysis in the electrolysis of CO2 and / or CO. After process step S4, process 1 ends.

[0066] Fig. 3 shows a schematic representation of an exemplary electrolysis device 100 in which the gas diffusion electrode 23 is used as cathode 3.

[0067] The electrolysis device 100 comprises an electrolysis cell 2 with a cathode chamber 6 and an anode chamber 7, which are separated from each other by a membrane 8, wherein the membrane 8 comprises, for example, a perfluorinated copolymer with sulfo groups, also known under the name Nafion ® , may contain. A cathode 3 is arranged in the cathode compartment 6 and an anode 4 is arranged in the anode compartment 7, wherein the cathode 3 and the anode 4 are connected to a power supply device 17.

[0068] To carry out the electrolysis, CO2 and / or CO is supplied to the cathode chamber 6 via a gas inlet 9, which is reduced at the cathode 3 to the desired electrolysis product, also referred to as the value product, e.g. ethene, and can be discharged from the cathode chamber 6 via a product outlet 11.

[0069] The anode compartment 7 contains an aqueous electrolyte 18, from which oxygen is formed at the anode 4. The cathode compartment 6 also contains an aqueous electrolyte 18, which may be identical to the aqueous electrolyte in the anode compartment 7 or may have a different composition.

[0070] The cathode 3 or working electrode in the embodiment is the gas diffusion electrode 23 of the Fig. 2. The copper-containing catalyst 5 of the gas diffusion electrode 23 catalyzes the desired electrolysis reaction.

[0071] Fig. 4 shows a representation of the Faraday efficiency FE ( Fig. 4 above) and partial current density j ( Fig. 4 below) for products of a CO2 electrolysis using the gas diffusion electrode 23 according to Fig. 2. The CO2 electrolysis was carried out over 20 h at a constant potential of - 1.6 V vs. Ag / AgCl (3 M).

[0072] The formula symbols -j and j effdenote the same physical quantity, i.e., the current that is effectively used to form a specific product or products and is neither used for another product nor lost through parasitic conductivity. To determine -j or j eff The number of molecules of a specific type formed per unit of time (exhaust gas flow and proportion of the respective gas) is measured. The number of electrons required to form a molecule, i.e., the charge required per molecule, is known from the chemical reaction equation.

[0073] From this, the partial current used for the formation of this molecule can be calculated as current density (area of ​​the electrolysis electrode).

[0074] It is shown that the gas diffusion electrode 23 exhibits excellent selectivity for ethene (C2H4), i.e., a nearly constant high Faraday efficiency of approximately 50% for ethene is observed over 20 hours, while the Faraday efficiency of the undesired byproduct hydrogen increased only slightly from approximately 8% Faraday efficiency to approximately 20% Faraday efficiency. The partial current densities j behave accordingly.

[0075] In Fig. 5 shows a flow diagram of another exemplary method 10 for forming a catalyst 5 for electrocatalysis. In contrast to the method described with reference to Fig. 1 and Fig.In the process 1 described in section 2, the catalyst 5 is not newly produced, but rather an existing and partially deactivated copper-based catalyst 5 is reactivated. The partially deactivated catalyst 5 represents the catalyst starting material 17. For example, the process 10 can be used to reactivate the catalyst 5 newly formed according to process 1 for the electrolysis of CO2 and / or CO, e.g., after electrolysis operation for several weeks or months.

[0076] After starting process 10, process steps S1 to S3 are carried out analogously to process steps S1 to S3 of process 1, i.e., the partially deactivated catalyst 5 as catalyst starting material 17 is contacted with an oxidizing agent composition 18 and at least partially oxidized, resulting in the formation of nanoneedles of copper(I) oxide. In process step S3, the oxidizing agent composition 18 is removed, and process 10 is subsequently terminated. The catalyst 5 or the gas diffusion electrode 23 provided therewith can now be used again for the electrolysis of CO2 and / or CO with high selectivity for the desired product of value, e.g., ethene.

[0077] The described processes 1 and 10 are cost-effective because only conventional copper granules are used as the raw material for the catalyst 5. Furthermore, they are comparatively time-consuming. Instead of a complex catalyst synthesis plus a step for applying the catalyst 5 to the conductor layer 22, both are carried out simultaneously in a single, time-efficient step.

[0078] Perhaps the greatest advantage is that storage of the nanomaterials is eliminated. As already explained, nanomaterials are often subject to aging over time. The use of nanomaterials therefore requires either uneconomical production in small batch sizes or the acceptance of a temporary change in the catalyst. Complex storage under protective gas can potentially slow aging, but is also costly and does not completely prevent aging. In the proposed processes 1, 10, the nanomaterials are produced on demand immediately before use, thus completely avoiding aging due to storage.

[0079] The catalyst 5 formed by processes 1, 10 shows a high selectivity for ethylene in the electrochemical CO2 reduction during electrolysis at application-related current densities (typically 200-800 mA / cm 2geometric electrode surface) and is at least equivalent to conventional catalysts in this respect.

[0080] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited to the disclosed examples and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention.

[0081] In summary, the invention relates to a method 1, 10 for forming a catalyst 5 for electrocatalysis. The method 1, 10 comprises contacting a catalyst starting material 17 arranged on an electrode substrate 16 with an oxidizing agent composition 18 s1 and at least partially oxidizing the catalyst starting material 17 by means of the oxidizing agent composition 18.

[0082] In addition, the invention relates to a catalyst 5 and a device 100 for electrocatalysis as well as the use of a catalyst 5. List of reference symbols 1 procedure 2 electrolysis cells 3 Cathode 4 Anode 5 Catalyst 6 Cathode compartment 7 Anode compartment 8 Membran 9 Gas inlet 10 procedures 11 Product outlet 12 gaseous products 13 liquid products 14 Power supply device 15 aqueous electrolyte 16 Electrode substrate 17 Catalyst starting material 18 Oxidizing agent composition 19 Binder material 20 Carrier layer 21 hydrophobic layer 22 Conductor layer 23 Gas diffusion electrode 100 device S0 Coating the electrode substrate with the catalyst starting material S1 Contacting a catalyst starting material arranged on an electrode substrate with an oxidizing agent composition S2 at least partially oxidizing the catalyst starting material by means of the oxidizing agent composition S3 Removal of the oxidizing agent composition S4 Applying a binder material to the oxidized catalyst starting material QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited non-patent literature

[0000] J. Zhang, W. Luo, A. Züttel, J. Mater. Chem. A, 7, 26285-26292 (2019), doi: 10.1039 / c9ta06736a

[0007]

Claims

[1] Method (1, 10) for forming a catalyst (5) for electrocatalysis, the method (1) comprising: - S1: bringing a catalyst starting material (17) arranged on an electrode substrate (16) into contact with an oxidizing agent composition (18) and - S2: at least partially oxidizing the catalyst starting material (17) and / or removing organic deposits on the catalyst starting material by means of the oxidizing agent composition (18). [2] Method (1) according to claim 1, comprising: - S0: Coating the electrode substrate (15) with the catalyst starting material (16). [3] Method (1) according to claim 2, wherein the coating of the electrode substrate (16) is carried out by means of a PVD process. [4] Method (1) according to one of the preceding claims, the method comprising: - S4: Applying a binder material (19) to the oxidized catalyst starting material (17). [5] The process (10) according to claim 1, wherein the catalyst starting material (17) is an at least partially deactivated catalyst (5). [6] Method (1, 10) according to one of the preceding claims, wherein the electrode substrate (16) is a gas diffusion electrode. [7] The method (1, 10) according to any one of the preceding claims, wherein the catalyst starting material (17) comprises at least one material selected from a group comprising copper, copper-containing compounds, silver, silver-containing compounds, gold, gold-containing compounds, lead, lead-containing compounds, zinc, zinc-containing compounds, tin and tin-containing compounds. [8] The method (1, 10) according to any one of the preceding claims, wherein the oxidizing agent composition (18) comprises at least one composition selected from a group comprising an aqueous solution of ammonium peroxodisulfate and sodium hydroxide, an aqueous hydrogen peroxide solution, an aqueous perchlorate solution, an aqueous nitric acid solution, and an aqueous sulfuric acid solution. [9] Method (1, 10) according to one of the preceding claims, wherein the oxidation of the catalyst starting material (17) takes place without applying an electrical potential. [10] Method (1, 10) according to one of the preceding claims, wherein the duration of the oxidation is between 5 min and 5 h, preferably between 20 min and 1 h. [11] Catalyst (5) for electrocatalysis, obtainable by means of a process (1, 10) according to one of claims 1 to 10. [12] Use of a catalyst (5) formed according to a process (1, 10) according to one of claims 1 to 10 or of a catalyst (5) according to claim 11 for electrocatalysis. [13] Use according to claim 12, wherein the electrocatalysis is carried out during the electrolysis of CO2 and / or CO. [14] Device (100) for electrocatalysis, the device (100) comprising a catalyst (5) designed according to one of claims 1 to 9 or a catalyst (5) according to claim 11. [15] Device (100) according to claim 14, wherein the catalyst (5) is formed on a gas diffusion electrode (23). [16] Device (100) according to claim 14 or 15, designed for the electrolysis of CO2 and / or CO.

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