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 a catalyst starting material (17) arranged on an electrode substrate (16) into contact with an oxidising agent composition (18) and at least partly oxidising the catalyst starting material (17) by means of the oxidising agent composition (18). The invention further relates to a catalyst (5), to a device (100) for electrocatalysis, and to the use of a catalyst (5).

Description

[0001] Description

[0002] Method for forming a catalyst for electrocatalysis, catalyst and device for electrocatalysis

[0003] 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.

[0004] 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.

[0005] 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, so that the electrochemical reduction of CO2 or CO can take place at high current densities at a three-phase boundary between the catalyst, the CO2 or CO, and the electrolyte.

[0006] 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 usually suffer from poor storage stability.

[0007] Over time, the material can agglomerate or oxidize into larger particles. This means that the age of a material batch can have a direct impact on the electrolysis process, such as its product distribution and stability, which is detrimental to a highly reliable technology.

[0008] To the authors' knowledge, this problem has been addressed little to date. Since electrochemical CCt 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.

[0009] 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.

[0010] 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 applied to form the gas diffusion layer. In a fourth process step, the material 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 storage stability of the finished gas diffusion electrode also exists here.

[0011] Against this background, it is the 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.

[0012] This problem is solved by the subject matter of the independent claims. The dependent claims relate to embodiments of these inventive solutions.

[0013] A first aspect of the invention relates to a method for forming a catalyst for electrocatalysis.

[0014] Electrocatalysis is a heterogeneous catalysis that lowers the activation energy of electrochemical reactions at an electrode surface. It allows 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.

[0015] Electrocatalysis is a low-temperature process, i.e. it is carried out at temperatures below 100°C. In this respect, catalysts suitable 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. In addition, catalysts for electrocatalysis are electrically conductive or can be connected or bonded in a conductive manner. Forming a catalyst means that a catalyst is produced that can be used immediately, i.e. a catalyst that is already activated. The proposed process can be used to form a new catalyst, i.e. for the first time, but also to reactivate a previously existing catalyst, which may, for example, have been previously activated.has been at least partially deactivated over time due to catalytic processes, e.g. by reduction, agglomeration, etc., of the catalyst material, and therefore requires reactivation.

[0016] Accordingly, the electrode substrate may 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.

[0017] 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, so that the catalyst is formed. The duration of the oxidation can be between 5 min and 5 h, preferably between 20 min and 1 h, for example, depending on the strength of the oxidizing agent and the temperature.

[0018] The oxidizing agent composition can then be removed, e.g., by washing with water and / or a solvent, e.g., ethanol, thereby preventing the oxidizing agent composition from influencing the electrocatalysis. The oxidizing agent composition can, in particular, be an aqueous composition, e.g., an aqueous solution of an oxidizing agent, optionally with additives, e.g., for pH adjustment. In this respect, the oxidation to be carried out can be a wet-chemical oxidation.

[0019] Oxidation of the catalyst starting material can lead to 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.

[0020] In general, it is possible that only a portion of the catalyst starting material is oxidized, e.g. in areas close to the surface where direct contact with the oxidizing agent composition is possible. If, for example, a metallic catalyst starting material is used, a portion of the metallic catalyst starting material can be oxidized so that two partial layers form in the original layer of the catalyst starting material: a partial layer with non-oxidized, metallic catalyst starting material and an overlying partial layer with oxidized catalyst starting material. The partial layer with non-oxidized, metallic catalyst starting material can, for example, be used as a collector layer of the electrode, while the partial layer with oxidized catalyst starting material forms the catalyst.

[0021] 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 the electrocatalysis. In addition, 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, tempering at an elevated temperature, e.g. a temperature above 100 °C, can be omitted, i.e. the process can be carried out without tempering at a temperature above 100 °C.The in situ formation of the catalyst also provides increased occupational safety, as, for example, no particulate nanomaterials need to be stored and transported.

[0022] Preferably , the formed catalyst has a large surface area with a roughness on the atomic scale that is readily wettable by water .

[0023] According to various embodiments, the method may comprise coating the electrode substrate with the catalyst starting material.

[0024] Before bringing the catalyst starting material into contact with the oxidizing agent composition, the latter can be applied to the electrode substrate, e.g., a carrier layer or a hydrophobic layer, in order to obtain the catalyst material arranged on the electrode substrate. This corresponds to a process step in the initial production of an electrode provided with a catalyst. 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.

[0025] The coating of the electrode substrate can preferably be carried out by means of a PVD process, e.g., by means of thermal evaporation or sputtering. Using these processes, a particularly uniform or homogeneous layer of the catalyst starting material, e.g., based on 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.

[0026] 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.

[0027] The binder material can be, for example, a resin or a polymer. Preferably, the binder material can be an anion- or cation-conducting ionomer, e.g., based on polytetrafluoroethylene such as a sulfonated tetrafluoroethylene polymer, for example Nafion®, or ionomers with imidazolium ligands, for example Sustainion®.

[0028] The binder material can be applied using, for example, a dipping or spraying process, squeegee printing, screen printing or a roll-to-roll process.

[0029] 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.

[0030] According to further embodiments, the catalyst starting material can be an at least partially deactivated catalyst.

[0031] In other words, the proposed method can be used to reactivate an at least partially deactivated catalyst. In this case, the rough surface structure can be restored by oxidation of the catalyst starting material and / or organic deposits that impair catalysis can be removed oxidatively. Catalysts often lose their electrocatalytic activity completely or partially after 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 operating time, 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.

[0032] 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.

[0033] 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.

[0034] According to various embodiments, the electrode substrate can be a gas diffusion electrode.

[0035] 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 carrier layer or hydrophobic layer.

[0036] 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.

[0037] 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.

[0038] Examples of compounds containing copper, silver, gold, lead, zinc, or tin include oxides or alloys containing copper, silver, gold, lead, zinc, or tin with other metals, or alloys of the aforementioned metals with each other and / or alloys with gold, ruthenium, and / or base metals. Of course, the catalyst starting material may contain several of the aforementioned materials.

[0039] 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 significant amounts of C-C bonds.

[0040] More preferably, the catalyst starting material can comprise metallic copper 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 conductor 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 conductor layer, while an upper partial layer arranged above it can be oxidized to the catalyst using the oxidizing agent composition.

[0041] 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.

[0042] Of course, the oxidizing agent composition may comprise several of the compositions mentioned.

[0043] The compositions mentioned are, in particular in combination with a copper-containing catalyst starting material, capable of causing oxidation with the formation of nanostructures, e.g. nanoneedles, which are particularly well suited for electrocatalysis.

[0044] According to further embodiments, the oxidation of the catalyst starting material can be carried out without applying an electrical potential.

[0045] Compared to processes that induce oxidation by applying an electrical potential, the proposed process involves oxidation using the oxidant composition, in particular wet-chemical oxidation. Such oxidation is more controllable and can lead to a structure exhibiting higher catalytic activity. It can be carried out 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, since any organic surface contaminants that could lead to reduced activity are removed by oxidation.

[0046] A further aspect of the invention relates to a catalyst for electrocatalysis which is obtainable by means of one of the processes described above.

[0047] Therefore, the above explanations of these processes also serve to describe the proposed catalyst. The advantages of the process are correspondingly associated with the proposed catalyst.

[0048] Such a catalyst is characterized by its nanostructuring, e.g. in the form of nanoneedles, which contribute to improved selectivity of catalysis.

[0049] 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.

[0050] 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.

[0051] Electrocatalysis can be carried out in particular during the electrolysis of CO2 and / or CO.

[0052] A further aspect of the invention relates to an electrocatalysis device comprising a catalyst formed according to one of the processes described above or a catalyst obtainable by such a process. Therefore, the above explanations for explaining these processes also serve to describe the proposed device. The advantages of the process 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, i.e. 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 the figures show the following:

[0056] Figure 1 is a flow chart of an exemplary method;

[0057] Figure 2A-C is a schematic representation of the production of an exemplary gas diffusion electrode with catalyst;

[0058] Figure 3 is a schematic representation of an exemplary electrolysis device;

[0059] Figure 4 shows the Faraday efficiency and partial current density curves for products of a CO2 electrolysis using the gas diffusion electrode according to Figure 2C over 20 hours at a constant potential of -1.6 V vs. Ag / AgCl (3 M); and

[0060] Figure 5 is a flow chart of a further exemplary method. With reference to Figure 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 production of a highly functional, nanostructured catalyst layer cost-effectively and only when needed by controlled oxidation of conventional copper layers in a wet-chemical process. Figure 2 shows the associated gas diffusion electrode 23 (Figure 2 bottom) and intermediate steps in its production.

[0061] After the start of method 1, in method step 50, 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 the surface of which a microporous, hydrophobic layer 21 is arranged. The carrier layer 20 is mechanically stable and can have fibers, for example in the form of a fiber lay, woven, knitted or crocheted fabric. Both the carrier layer 20 and the hydrophobic layer 21 are porous in order to enable the supply of gaseous starting materials and the removal of gaseous products through the layers 20, 21 when the gas diffusion electrode 23 is used.

[0062] In process step S0, the surface of the hydrophobic layer 21 is coated with the catalyst starting material 17 by means of thermal evaporation. In the exemplary embodiment, inexpensive conventional copper granulate serves as the raw material for thermal evaporation, so that a metallic copper layer is formed as the catalyst starting material 17. Figure 2A shows the corresponding state after completion of process step S0, wherein the catalyst starting material 17 is arranged on the electrode substrate 16. It should be noted that the hydrophobic layer 21 is only optionally present in order to prevent the penetration of the liquid aqueous electrolyte when the gas diffusion electrode 23 is used. In other words, the catalyst starting material 17 can, for example, also be deposited directly on the carrier layer 20.In addition, other catalyst starting materials 17 can of course also be used to coat the electrode substrate 16.

[0063] In the subsequent process step S1, the catalyst starting material 17 arranged on the electrode substrate 16 is briefly brought into contact, e.g., immersed, with an oxidizing agent composition 18, i.e., for a period of between 20 minutes and 1 hour, for example, for approximately 45 minutes. 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 means of the oxidizing agent composition 18. No electrical potential is applied.

[0064] In the exemplary embodiment, an aqueous solution of ammonium peroxodisulfate and sodium hydroxide is used as the oxidizing agent composition 18.

[0065] By partially oxidizing the catalyst starting material 17, two partial layers are obtained. A lower first partial layer, 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 partial layer forms the electrically conductive collector layer 22 of the gas diffusion electrode 23. The collector layer

[0066] 22 has the task of enabling good electrical conductivity in the plane, so that the gas diffusion electrode

[0067] 23 can be contacted from the edge.

[0068] 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. Figure 2B shows the corresponding state after completion of process step S2.

[0069] 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 (not shown in Figure 2).

[0070] 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 (Nation®) was used as the binder material 19. In Figure 2, this is represented by a block arrow labeled "+19." The binder material 19 fixes the copper(II) oxide nanoparticles to the collector layer 22, so that the resulting gas diffusion electrode 23 (Figure 20) is immediately ready for use and can be used, for example, for electrocatalysis in the electrolysis of CO2 and / or O2. After process step S4, process 1 ends.

[0071] Figure 3 shows a schematic representation of an exemplary electrolysis device 100 in which the gas diffusion electrode 23 is used as cathode 3.

[0072] The electrolysis device 100 comprises an electrolysis cell 2 with a cathode compartment 6 and an anode compartment 7, which are separated from each other by a membrane 8. The membrane 8 may contain, for example, a perfluorinated copolymer with sulfo groups, also known under the name Nafion®. A cathode 3 is arranged in the cathode compartment 6, and an anode 4 is arranged in the anode compartment 7. The cathode 3 and the anode 4 are connected to a power supply 17.

[0073] To carry out the electrolysis, CO2 and / or CO is fed 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.

[0074] 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.

[0075] In the exemplary embodiment, the cathode 3 or working electrode is the gas diffusion electrode 23 of Figure 2. The copper-containing catalyst 5 of the gas diffusion electrode 23 catalyzes the desired electrolysis reaction.

[0076] Figure 4 shows a representation of the curves of Faraday efficiency FE (Figure 4 above) and partial current density j (Figure 4 below) for products of a COf electrolysis using the gas diffusion electrode 23 according to Figure 2. The CCp electrolysis was carried out for 20 h at a constant potential of - 1.6 V vs. Ag / AgCl (3 M).

[0077] The formula symbols -j and j eff denote 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. From this, the partial current used to form this molecule can be calculated as the current density (area of ​​the electrolysis electrode).

[0078] It is shown that the gas diffusion electrode 23 exhibits excellent selectivity for ethene (C2H4). This means that a nearly constant high Faraday efficiency of approximately 50% is observed for ethene 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.

[0079] Figure 5 shows a flow diagram of another exemplary method 10 for forming a catalyst 5 for electrocatalysis. In contrast to method 1 described with reference to Figures 1 and 2, the catalyst 5 is not newly produced here, 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 method 10 can be used to reactivate the catalyst 5 newly formed according to method 1 for the electrolysis of CO2 and / or CO, e.g., after electrolysis operation for several weeks or months.

[0080] After the start of the process 10, the process steps S1 to S3 are carried out analogously to the process steps S1 to S3 of the process 1, ie the partially deactivated catalyst 5 as catalyst starting material 17 is brought into contact with an oxidizing agent composition 18 and at least partially oxidized, whereby nanoneedles of copper(I) oxide are formed. In process step S3, the oxidizing agent composition 18 is removed and the 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.

[0081] The described processes 1, 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.

[0082] Possibly the biggest advantage is that there is no need to store the nanomaterials. As already explained, nanomaterials are often subject to ageing over time. The use of nanomaterials therefore either requires uneconomical production in small batch sizes or requires the acceptance of a change in the catalyst over time. Complex storage in a protective gas can slow down ageing, but is also expensive and does not prevent ageing completely. In the proposed processes 1, 10, the nanomaterials are produced on demand immediately before use, so that ageing through storage can be completely avoided.

[0083] The catalyst 5 formed by the processes 1, 10 shows a high selectivity for ethene in the electrochemical C02 reduction in electrolysis under application-related current densities (typically 200-800 mA / cm 2geometric electrode surface ) and is in this respect at least equivalent to conventional catalysts .

[0084] 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 can be derived therefrom by those skilled in the art without departing from the scope of the invention.

[0085] 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 and at least partially oxidizing the catalyst starting material 17 by means of the oxidizing agent composition 18.

[0086] In addition, the invention relates to a catalyst 5 and a device 100 for electrocatalysis as well as the use of a catalyst 5.

[0087] Reference symbol list

[0088] 1 procedure

[0089] 2 electrolysis cells

[0090] 3 Cathode

[0091] 4 Anode

[0092] 5 Catalyst

[0093] 6 Cathode compartment

[0094] 7 Anode compartment

[0095] 8 Membran

[0096] 9 Gas inlet

[0097] 10 procedures

[0098] 11 Product outlet

[0099] 12 gaseous products

[0100] 13 liquid products

[0101] 14 Power supply device

[0102] 15 aqueous electrolyte

[0103] 16 Electrode substrate

[0104] 17 Catalyst starting material

[0105] 18 Oxidizing agent composition

[0106] 19 Binder material

[0107] 20 Carrier layer

[0108] 21 hydrophobic layer

[0109] 22 Conductor layer

[0110] 23 Gas diffusion fusion electrode

[0111] 100 device

[0112] 50 Coating the electrode substrate with the catalyst starting material

[0113] 51 Contacting a catalyst starting material arranged on an electrode substrate with an oxidizing agent composition

[0114] 52 at least partially oxidizing the catalyst starting material by means of the oxidizing agent composition

[0115] 53 Removal of the oxidizing agent composition S4 Application of a binder material to the oxidized

[0116] Catalyst starting material

Claims

Patent claims 1. A method (1, 10) for forming a catalyst (5) for electrocatalysis, the method (1) comprising: - Sl: 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: - SO: 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. The method (1, 10) according to any one of the preceding claims, wherein the oxidation of the catalyst starting material (17) takes place without applying an electrical potential.

10. Process (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 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. The device (100) according to claim 14, wherein the catalyst (5) is formed on a gas diffusion electrode (23).

16. The device (100) according to claim 14 or 15, designed for the electrolysis of CO2 and / or CO.

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