Production method of catalyst layer, film-catalyst layer conjugate, and water electrolysis apparatus

Abstract

To provide a technique by which multiple cavities are formed in a catalyst layer.SOLUTION: With a mixture of multiple catalyst particles, an ionomer, a solvent, and a surfactant with critical micelle concentration or more, a catalyst ink is prepared in which micelles 80 are formed by surfactant molecules 81. The catalyst ink is applied on a polymer electrolyte. Multiple cavities are formed in the catalyst layer by removing the surfactant from the catalyst layer produced like that.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a catalyst layer, a membrane-catalyst layer laminate, and a water electrolysis device.

Background Art

[0002] Conventionally, a solid polymer type water electrolysis device that produces hydrogen (H2) by electrolyzing water (H2O) is known. The water electrolysis device has a cell stack in which cells and separators are alternately laminated. Each cell has an electrolyte membrane and catalyst layers formed on both sides of the electrolyte membrane. When using a PEM (Proton Exchange Membrane) type water electrolysis device, a voltage is applied between the catalyst layer on the anode side and the catalyst layer on the cathode side, and water is supplied to the catalyst layer on the anode side. As a result, the following electrochemical reactions occur in the catalyst layer on the anode side and the catalyst layer on the cathode side. As a result, hydrogen is discharged from the catalyst layer on the cathode side. (Anode side) 2H2O → 4H + + O2+ 4e - (Cathode side) 2H + + 2e - → H2

[0003] Conventional water electrolysis devices are described in, for example, Patent Document 1.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When using a water electrolysis device, as described above, in the catalyst layer on the anode side, water becomes hydrogen ions (H + ), oxygen (O2), and electrons (e- ) is electrolyzed. Therefore, in the catalyst layer on the anode side, it is necessary to supply liquid water and discharge gaseous oxygen. However, when the oxygen discharge property is low, oxygen accumulates in the catalyst layer, and the supply of water is inhibited by the accumulated oxygen. As a result, there is a problem that the efficiency of electrolysis on the anode side decreases.

[0006] In order to efficiently discharge oxygen from the catalyst layer on the anode side, it is desirable to provide appropriate voids in the catalyst layer. Therefore, an object of the present invention is to provide a technique capable of forming a plurality of voids in the catalyst layer.

Means for Solving the Problems

[0007] To solve the above problems, a first invention of the present application is a method for manufacturing a catalyst layer, comprising a preparation step of mixing a plurality of catalyst particles, an ionomer, a solvent, and a surfactant at a concentration equal to or higher than the critical micelle concentration to prepare a catalyst ink in which micelles are formed by the molecules of the surfactant, and a coating step of applying the catalyst ink onto the surface of an electrolyte membrane.

[0008] A second invention of the present application is the manufacturing method of the first invention, wherein the weight ratio of the surfactant to the solvent in the catalyst ink is 0.01 wt% or more and 20.0 wt% or less.

[0009] A third invention of the present application is the manufacturing method of the first invention or the second invention, wherein the diameter of the micelles in the catalyst ink is 10 nm or more and 100 nm or less.

[0010] A fourth invention of the present application is the manufacturing method of the first invention or the second invention, further comprising a drying step of drying the catalyst ink at a temperature lower than the decomposition temperature of the surfactant after the coating step.

[0011] A fifth invention of the present application is the manufacturing method of the fourth invention, further comprising a conditioning step of removing the surfactant from the catalyst layer by flowing water through the catalyst layer after the drying step.

[0012] The sixth invention of the present application is a membrane-catalyst layer conjugate including an electrolyte membrane and a catalyst layer formed on the surface of the electrolyte membrane, wherein the catalyst layer contains a plurality of catalyst particles, an ionomer, and a surfactant, and the surfactant is dispersed in the catalyst layer.

[0013] The seventh invention of the present application is a water electrolysis device including a membrane-catalyst layer conjugate, wherein the catalyst layer is an anode catalyst layer.

Advantages of the Invention

[0014] According to the first to fifth inventions of the present application, by removing the surfactant from the produced catalyst layer, a plurality of cavities can be formed in the catalyst layer.

[0015] In particular, according to the second invention of the present application, a large number of micelles can be formed in the catalyst ink.

[0016] In particular, according to the fourth invention of the present application, the catalyst ink can be dried while suppressing the decomposition of the surfactant constituting the micelles in the catalyst ink.

[0017] According to the sixth to seventh inventions of the present application, by removing the surfactant from the catalyst layer, a large number of cavities can be formed in the catalyst layer.

[0018] In particular, according to the seventh invention of the present application, due to the large number of cavities formed in the anode catalyst layer, the fluidity of water and oxygen in the anode catalyst layer can be improved. Therefore, oxygen can be efficiently discharged from the anode catalyst layer, and water can be efficiently supplied to the anode catalyst layer. As a result, the efficiency of electrolysis in the anode catalyst layer can be improved.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0021] <1. Water electrolysis device according to an embodiment> FIG. 1 is a schematic diagram of a polymer electrolyte type water electrolysis device 1 according to an embodiment of the present invention. This water electrolysis device 1 is a device for producing hydrogen by water electrolysis. As shown in FIG. 1, the water electrolysis device 1 includes a cell stack 30 composed of a plurality of cells 10 and a plurality of separators 20, and a power source 40 that applies a voltage to the cell stack 30. The cells 10 and the separators 20 are alternately stacked to form the cell stack 30.

[0022] FIG. 2 is a diagram schematically showing only one cell 10 of the cell stack 30 of the water electrolysis device 1 and a pair of separators 20 located on both sides of the cell 10. As shown in FIG. 2, one cell 10 has an electrolyte membrane 51, an anode catalyst layer 61, a porous transport layer 62, a cathode catalyst layer 71, and a gas diffusion layer 72.

[0023] The laminate composed of the electrolyte membrane 51, the anode catalyst layer 61, and the cathode catalyst layer 71 is called a membrane-catalyst layer assembly (CCM: Catalyst-coated membrane). Also, the laminate composed of the electrolyte membrane 51, the anode catalyst layer 61, the porous transport layer 62, the cathode catalyst layer 71, and the gas diffusion layer 72 is called a membrane-electrode assembly (MEA: Membrane-Electrode-Assembly).

[0024] The electrolyte membrane 51 is a thin plate-shaped membrane (ion exchange membrane) having ion conductivity. The electrolyte membrane 51 of the present embodiment is a proton exchange membrane that conducts hydrogen ions (H + +). A fluorine-based or hydrocarbon-based polymer electrolyte membrane is used for the electrolyte membrane 51. Specifically, as the electrolyte membrane 51, for example, a polymer electrolyte membrane containing perfluorocarbon sulfonic acid is used. The membrane thickness of the electrolyte membrane 51 is, for example, 5 μm to 200 μm.

[0025] The anode catalyst layer 61 is a catalyst layer that causes an electrochemical reaction on the anode side. The anode catalyst layer 61 is formed on the surface of the anode side of the electrolyte membrane 51. The anode catalyst layer 61 includes a plurality of catalyst particles and an ionomer.

[0026] The catalyst particles are particles having a catalytic action for causing electrolysis of water. The catalyst particles are made of, for example, iridium (Ir), ruthenium (Ru), iridium oxide (IrOx), platinum (Pt), or an alloy of iridium (Ir) and ruthenium (Ru). The catalyst particles may be supported by a carrier. For the carrier, for example, titanium dioxide (TiO2) or carbon (C) is used.

[0027] The ionomer is an electrolyte polymer that covers the catalyst particles. The ionomer serves to transport hydrogen ions generated by electrolysis of water within the anode catalyst layer 61. For the ionomer, for example, Nafion (perfluorocarbon sulfonic acid) is used. The ionomer has a polymer chain structure having an ion exchange group such as a sulfone group. The hydrogen ions combine with water in the anode catalyst layer 61 to become oxonium ions (H3O + +). Then, the oxonium ions propagate along the ion exchange groups of the ionomer.

[0028] When the water electrolysis device 1 is in use, water (H2O) is supplied to the anode catalyst layer 61. Then, a voltage is applied between the anode catalyst layer 61 and the cathode catalyst layer 71 by the power source 40. Then, due to the voltage and the action of the catalyst particles, water is electrolyzed into hydrogen ions (H + ), oxygen (O2), and electrons (e - ) in the anode catalyst layer 61. That is, the following electrochemical reaction occurs in the anode catalyst layer 61. 2H2O → 4H + + O2+ 4e -

[0029] The porous transport layer (PTL: Porous Transport Layer) 62 is a layer for uniformly supplying water from the separator 20 to the anode catalyst layer 61 and sending the oxygen and electrons generated in the anode catalyst layer 61 to the separator 20. The porous transport layer 62 is laminated on the outside of the anode catalyst layer 61 (the side opposite to the electrolyte membrane 51). The porous transport layer 62 has conductivity and is formed of a porous material. For the porous transport layer 62, for example, a porous base material formed of metallic titanium or a titanium alloy is used.

[0030] The cathode catalyst layer 71 is a catalyst layer that causes an electrochemical reaction on the cathode side. The cathode catalyst layer 71 is formed on the surface of the cathode side of the electrolyte membrane 51 (the surface opposite to the surface on which the anode catalyst layer 61 is formed). The cathode catalyst layer 71 includes a large number of carbon particles carrying catalyst particles. The catalyst particles are, for example, platinum particles. However, the catalyst particles may be a mixture of platinum particles and a small amount of ruthenium or cobalt particles.

[0031] When the water electrolysis device 1 is in use, hydrogen ions (H + ) and electrons (e -) are supplied. Then, a voltage is applied between the anode catalyst layer 61 and the cathode catalyst layer 71 by the power source 40. Then, due to the voltage and the action of the catalyst particles, a reduction reaction occurs in the cathode catalyst layer 71, and hydrogen gas (H2) is generated from hydrogen ions and electrons. That is, the following electrochemical reaction occurs in the cathode catalyst layer 71. 2H + + 2e - → H2

[0032] The gas diffusion layer (GDL: Gas Diffusion Layer) 72 is a layer for sending electrons from the separator 20 to the cathode catalyst layer 71 and sending the hydrogen generated in the cathode catalyst layer 71 to the separator 20. The gas diffusion layer 72 is laminated on the outside of the cathode catalyst layer 71 (the side opposite to the electrolyte membrane 51). The gas diffusion layer 72 has conductivity and is formed of a porous material. For example, a porous base material (carbon paper) formed of carbon is used for the gas diffusion layer 72.

[0033] The separator 20 is a layer for moving electrons between adjacent cells 10 and forming passages for water, oxygen, and hydrogen. The separator 20 is interposed between the porous transport layer 62 and the gas diffusion layer 72 of adjacent cells 10. The separator 20 has conductivity and is formed of a material that does not permeate gas and liquid. For example, a metal plate is used as the separator 20.

[0034] The separator 20 has an anode surface 21 in contact with the porous transport layer 62 and a cathode surface 22 in contact with the gas diffusion layer 72. A plurality of anode grooves 23 are formed in the anode surface 21. Water is supplied from the outside of the cell stack 30 to the porous transport layer 62 through the anode grooves 23 of the separator 20. Also, the oxygen generated in the anode catalyst layer 61 passes through the porous transport layer 62 and is discharged to the outside of the cell stack 30 through the anode grooves 23 of the separator 20.

[0035] In addition, a plurality of cathode grooves 24 are formed on the cathode surface 22 of the separator 20. The hydrogen generated in the cathode catalyst layer 71 passes through the gas diffusion layer 72, passes through the cathode grooves 24 of the separator 20, and is discharged to the outside of the cell stack 30.

[0036] The power source 40 is a device that applies a voltage to the above-described cell stack 30. As shown in FIG. 1, the terminal on the positive electrode side of the power source 40 is electrically connected to the separator 20 located at the most anode-side end of the cell stack 30. The terminal on the negative electrode side of the power source 40 is electrically connected to the separator 20 located at the most cathode-side end of the cell stack 30. The power source 40 applies a voltage necessary for electrolysis of water to the cell stack 30.

[0037] When the water electrolysis device 1 is in use, water is supplied from the anode groove 23 of the separator 20 to the anode catalyst layer 61 through the porous transport layer 62. Then, due to the voltage applied by the power source 40 and the action of the catalyst particles in the anode catalyst layer 61, water is decomposed into hydrogen ions, oxygen, and electrons. The hydrogen ions propagate through the electrolyte membrane 51 to the cathode catalyst layer 71. Oxygen is discharged to the outside of the cell stack 30 through the porous transport layer 62 and the anode groove 23. The electrons flow through the porous transport layer 62 and the separator 20 to the adjacent cell 10.

[0038] In the adjacent cell 10, the electrons reach the cathode catalyst layer 71 through the gas diffusion layer 72. Then, in the cathode catalyst layer 71, hydrogen ions and electrons combine to generate hydrogen. The generated hydrogen is discharged to the outside of the cell stack 30 through the gas diffusion layer 72 and the cathode grooves 24. Thereby, hydrogen is produced.

[0039] <2. Manufacturing Method of Anode Catalyst Layer> The above-described anode catalyst layer 61 is formed by applying catalyst ink on the surface of the electrolyte membrane 51. Hereinafter, the manufacturing method of the anode catalyst layer 61 will be described.

[0040] Figure 3 is a flowchart showing the manufacturing procedure of the anode catalyst layer 61. As shown in Figure 3, when manufacturing the anode catalyst layer 61, first, a catalyst ink for the anode catalyst layer 61 is prepared (step S1: preparation step).

[0041] In the preparation step of step S1, a plurality of catalyst particles, an ionomer, and a surfactant are added to a solvent, and these are mixed by stirring. The solvent is water, alcohol, or both of them. The alcohol is, for example, methanol, ethanol, 1-propanol, or 2-propanol, etc. The amount of the solvent is such that the concentration of the solid content in the catalyst ink is 1% or more and 20% or less. Also, the weight ratio of the ionomer to the catalyst particles is, for example, 1 wt% or more and 50 wt% or less, preferably 10 wt% or more and 30 wt% or less.

[0042] The surfactant is an additive for forming cavities 82, which will be described later, in the anode catalyst layer 61. As the surfactant, for example, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, or a nonionic surfactant can be used. Also, two or more types of surfactants may be added when preparing the catalyst ink.

[0043] The addition amount of the surfactant is such that the concentration of the surfactant in the catalyst ink is equal to or higher than the critical micelle concentration. The critical micelle concentration varies depending on the type of the surfactant, but in many cases, it is about 0.001 - 0.1 mol / l.

[0044] Figure 4 is a diagram conceptually showing the state of the surfactant in the catalyst ink. As shown in Figure 4, when a surfactant with a concentration equal to or higher than the critical micelle concentration is added, the surfactant molecules 81 form a large number of micelles 80 in the catalyst ink. The micelle 80 is a spherical mass formed by the aggregation of the surfactant molecules 81. The diameter d of the micelles 80 in the catalyst ink is, for example, 10 nm or more and 100 nm or less. The micelle 80 may be formed by the aggregation of the hydrophobic groups of each molecule 81 on the inside and the hydrophilic groups on the outside, or may be formed by the aggregation of the hydrophilic groups of each molecule 81 on the inside and the hydrophobic groups on the outside.

[0045] If the weight ratio of the surfactant to the solvent is too low, the molecules 81 of the surfactant do not form micelles 80 well. On the other hand, if the weight ratio of the surfactant to the solvent is too high, the catalyst ink is likely to generate unnecessary foaming. Therefore, the weight ratio of the surfactant to the solvent is desirably such that micelles 80 are formed well and no unnecessary foaming occurs. For example, the weight ratio of the surfactant to the solvent may be 0.01 wt% or more and 20.0 wt% or less.

[0046] Next, the above-described catalyst ink is applied to the surface of the electrolyte membrane 51 (step S2: application step). FIG. 5 is a diagram showing the state of the application step of step S2. As shown in FIG. 5, the application device 90 used in the application step includes a nozzle 91 that discharges the catalyst ink and a transport mechanism 92 that relatively moves the electrolyte membrane 51 with respect to the nozzle 91. The nozzle 91 may discharge the catalyst ink in a film shape from a slit-shaped discharge port, or may discharge the catalyst ink in a spray shape.

[0047] The application device 90 discharges the catalyst ink from the nozzle 91 onto the surface of the electrolyte membrane 51 while transporting the electrolyte membrane 51 by the transport mechanism 92. Thereby, the catalyst ink is applied to the surface of the electrolyte membrane 51. As described above, a large number of micelles 80 formed by the molecules 81 of the surfactant are present in the catalyst ink.

[0048] When the application step is completed, subsequently, the catalyst ink applied to the electrolyte membrane 51 is dried (step S3: drying step). In the drying step of step S3, for example, the electrolyte membrane 51 to which the catalyst ink is applied is carried into a drying furnace. Since the temperature in the drying furnace is higher than the ambient temperature, the vaporization of the solvent in the catalyst ink is promoted. Thereby, the catalyst ink dries.

[0049] However, it is desirable that the temperature in the drying furnace be lower than the decomposition temperature of the surfactant. This can prevent the surfactant in the catalyst ink from decomposing before the catalyst ink dries. Therefore, the catalyst ink can be dried while suppressing the collapse of the shape of the micelles 80 in the catalyst ink.

[0050] The catalyst ink applied to the surface of the electrolyte membrane 51 solidifies by the above drying process to become the anode catalyst layer 61. Also in the anode catalyst layer 61, the surfactant exists in a dispersed state at the locations where the micelles 80 were formed in the catalyst ink. That is, a large number of fine cavities 82 are formed in the anode catalyst layer 61 by the micelles 80 of the surfactant, and the surfactant is dispersed and present in the cavities 82.

[0051] Thereafter, a water electrolysis device 1 is manufactured using the membrane-catalyst layer assembly including the electrolyte membrane 51 and the above anode catalyst layer 61 (step S4: device manufacturing process). Specifically, a cell 10 is manufactured by adding a porous transport layer 62 and a gas diffusion layer 72 to a membrane-catalyst layer assembly composed of the electrolyte membrane 51, the anode catalyst layer 61, and the cathode catalyst layer 71. Then, a cell stack 30 is formed by alternately laminating the cells 10 and the separators 20. Thereafter, the water electrolysis device 1 is manufactured by connecting a power source 40 to the cell stack 30.

[0052] After the water electrolysis device 1 is manufactured and before using the water electrolysis device 1, water is passed through the anode catalyst layer 61 (step S5: conditioning process). Specifically, water is supplied from the anode groove 23 of the separator 20 to the anode catalyst layer 61 through the porous transport layer 62. Then, in the anode catalyst layer 61, the concentration of the surfactant in the water decreases, and the aggregation number of the micelles 80 decreases. As a result, the surfactant becomes movable between the catalyst particles and is flowed with the water. Then, the water containing the surfactant is discharged to the outside through the porous transport layer 62 and the anode groove 23 of the separator 20.

[0053] At this time, it is desirable to supply a sufficient amount of water so that the concentration of the surfactant in the anode catalyst layer 61 is equal to or lower than the critical micelle concentration. This promotes the decomposition of the micelles 80 and enables the surfactant to be discharged more efficiently.

[0054] FIG. 6 is a diagram conceptually showing the state of the conditioning process in step S5. In the conditioning process, the surfactant is washed away and removed by the water supplied to the anode catalyst layer 61. As a result, voids 82 remain at the locations where the surfactant was present in the anode catalyst layer 61 as shown in FIG. 6. Thereby, a large number of voids 82 are formed in the anode catalyst layer 61. Each of the voids 82 is not isolated and communicates with each other through fine gaps between the catalyst particles.

[0055] As described above, in the manufacturing method of the present embodiment, the catalyst ink in which the micelles 80 are formed by the surfactant molecules 81 is applied to the surface of the electrolyte membrane 51. Thereby, the anode catalyst layer 61 in which the surfactant is dispersed inside can be obtained. Then, before using the water electrolysis device 1, if water is passed through the anode catalyst layer 61 to remove the surfactant, a large number of voids 82 can be formed in the anode catalyst layer 61.

[0056] When the water electrolysis device 1 is in use, water is supplied to the anode catalyst layer 61, and the water is electrolyzed to generate gaseous oxygen. At this time, the large number of voids 82 formed in the anode catalyst layer 61 can improve the fluidity of water and oxygen in the anode catalyst layer 61. Therefore, oxygen can be efficiently discharged from the anode catalyst layer 61, and water can be efficiently supplied to the anode catalyst layer 61. As a result, the efficiency of electrolysis in the anode catalyst layer 61 can be improved.

[0057] Further, by changing the amount of the surfactant added in the above-described step S1, the amount of voids 82 in the anode catalyst layer 61 can be adjusted. Therefore, according to the above manufacturing method, the porosity of the anode catalyst layer 61 can be easily controlled. Therefore, the anode catalyst layer 61 having a porosity suitable for water electrolysis can be easily manufactured.

[0058] Also, the surfactant used to form the voids 82 in the anode catalyst layer 61 is discharged together with water in the conditioning step of step S5. For this reason, when the water electrolysis device 1 is actually used, the surfactant itself does not adversely affect the performance of water electrolysis.

[0059] <3. Modification Example> As described above, one embodiment of the present invention has been described, but the present invention is not limited to the above embodiment.

[0060] In the above embodiment, the case where a plurality of voids 82 are formed in the anode catalyst layer 61 has been described. However, in the same manner, a plurality of voids may be formed in the cathode catalyst layer 71. If a plurality of voids are formed in the cathode catalyst layer 71, gaseous hydrogen can be efficiently discharged from the cathode catalyst layer 71.

[0061] However, in the water electrolysis device 1, the reaction rate of electrolysis in the anode catalyst layer 61 is often slower than the reduction reaction rate in the cathode catalyst layer 71. For this reason, there is a situation where the processing speed of the entire water electrolysis device 1 is rate-limited by the reaction rate on the anode side. If a plurality of voids 82 are formed in the anode catalyst layer 61 as in the above embodiment to increase the reaction rate of electrolysis in the anode catalyst layer 61, the reaction efficiency of the entire water electrolysis device 1 can be improved. Therefore, forming a plurality of voids 82 in the anode catalyst layer 61 in the water electrolysis device 1 has particularly high technical significance.

[0062] In addition, in the above-described embodiment, the case where the present invention is applied to a PEM (Proton Exchange Membrane) type water electrolysis device 1 has been described. However, the present invention may also be applied to a water electrolysis device other than the PEM type, for example, an AEM (Anion Exchange Membrane) type water electrolysis device. In the AEM type water electrolysis device, for example, Ni, Co, Fe are used as the materials of the catalyst and the GDL, and a high-concentration alkaline solution such as KOH is used as the supply solution.

[0063] In addition, in the above-described embodiment, the case where a plurality of cavities 82 are formed in the catalyst layer of the cell 10 used in the water electrolysis device 1 has been described. However, in the same manner, a plurality of cavities may be formed in the catalyst layer of the cell used in the fuel cell. If a plurality of cavities are formed in the catalyst layer on the anode side of the fuel cell, the hydrogen supply efficiency can be improved. Also, if a plurality of cavities are formed in the catalyst layer on the cathode side of the fuel cell, the water discharge efficiency and the oxygen supply efficiency can be improved.

[0064] Also, a plurality of cavities may be formed in the catalyst layer of the cell used in the LOHC (Liquid Organic Hydrogen Carrier) process for producing an organic hydride (for example, toluene-methylcyclohexane) by hydrogenating an aromatic compound such as toluene in the same manner as above.

[0065] In addition, the respective elements appearing in the above-described embodiment and modified examples may be appropriately combined or partially deleted within a range where no contradiction occurs.

Explanation of Reference Numerals

[0066] 1: Water electrolysis device 10: Cell 20: Separator 30: Cell stack 40: Power source 51: Electrolyte membrane 61: Anode catalyst layer 62: Porous transport layer 71: Cathode catalyst layer 72: Gas diffusion layer 80: Micelle 81: Molecule 82: Cavity 90: Coating device 91: Nozzle 92: Conveyor mechanism

Claims

1. A method for manufacturing a catalyst layer, comprising: a preparation step of mixing a plurality of catalyst particles, an ionomer, a solvent, and a surfactant at a concentration equal to or higher than the critical micelle concentration to prepare a catalyst ink in which micelles are formed by the molecules of the surfactant; a coating step of applying the catalyst ink onto the surface of an electrolyte membrane; The manufacturing method comprising these steps.

2. The manufacturing method according to Claim 1, wherein the weight ratio of the surfactant to the solvent in the catalyst ink is 0.01 wt% or more and 20.0 wt% or less.

3. The manufacturing method according to Claim 1 or Claim 2, wherein the diameter of the micelles in the catalyst ink is 10 nm or more and 100 nm or less.

4. The manufacturing method according to Claim 1 or Claim 2, further comprising a drying step of drying the catalyst ink at a temperature lower than the decomposition temperature of the surfactant after the coating step. The manufacturing method comprising this step.

5. The manufacturing method according to Claim 4, further comprising a conditioning step of removing the surfactant from the catalyst layer by flowing water through the catalyst layer after the drying step. The manufacturing method comprising this step.

6. A membrane-catalyst layer bonded body comprising an electrolyte membrane; and a catalyst layer formed on the surface of the electrolyte membrane, wherein the catalyst layer contains a plurality of catalyst particles, an ionomer, and a surfactant, and the surfactant is dispersed in the catalyst layer.

7. A water electrolysis device comprising the membrane-catalyst layer bonded body according to Claim 6, wherein the catalyst layer is an anode catalyst layer.

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