Method for producing a porous transport composite layer, porous transport composite layer and use thereof

Abstract

This application discloses a method for preparing a porous transport composite layer, the porous transport composite layer itself, and its application. The preparation method includes: providing a porous transport substrate, the porous transport substrate including a surface to be plated; immersing the porous transport substrate in a hydrophobic material, so that the surface of the porous transport substrate is covered by the hydrophobic material, and the pores of the porous transport substrate are filled and covered by the hydrophobic material; removing the hydrophobic material from the surface to be plated of the porous transport substrate, exposing the surface to be plated, to obtain a first intermediate; placing the first intermediate in an electroplating solution and electroplating it to electroplat a protective layer on the surface to be plated of the porous transport substrate of the first intermediate, to obtain a second intermediate; removing the hydrophobic material from the surface and pores of the porous transport substrate of the second intermediate, to obtain a porous transport composite layer. This preparation method can save on the amount of precious metals used, reduce production costs, is simple in process, and is suitable for large-scale production.

Description

Technical Field

[0001] This application relates to the field of electroplating technology, and in particular to a method for preparing a porous transport composite layer, the porous transport composite layer and its application. Background Technology

[0002] In recent years, renewable energy-based water electrolysis hydrogen production technology has developed rapidly. Proton exchange membrane (PEM) water electrolysis devices have advantages such as compact structure, rapid start-up and shutdown, wide load range, and high efficiency, thus they are expected to become the mainstream technology for hydrogen production coupled with wind and solar power generation. Electrochemical hydrogen pumps are devices developed based on fuel cell structures, used for hydrogen purification and compression, and can be coupled with water electrolysis to produce high-purity, high-pressure hydrogen.

[0003] The porous metal transport layer is a critical and expensive component in PEM electrolyzers and electrochemical hydrogen pumps. Existing materials for porous metal transport layers include titanium fiber felt and porous sintered titanium. Research has revealed that a potential gradient exists across the cross-section of the porous metal transport layer at the anode of a PEM electrolyzer. As the distance between the porous metal transport layer and the catalyst layer increases, the potential of the porous metal transport layer cross-section drops sharply to below 1V (relative to a reversible hydrogen electrode). Therefore, if the surface of the porous metal transport layer adjacent to the catalyst layer is corroded or oxidized, it will severely affect the properties of the electrolyzer. Consequently, a coating is generally required on the surface of the porous metal transport layer adjacent to the catalyst layer to prevent corrosion.

[0004] Existing technologies typically employ physical or chemical methods such as physical vapor deposition (PVD), chemical vapor deposition (CVD), electroless plating, and electrochemical plating to deposit a dense nano-coating of noble metals (such as platinum or ruthenium-iridium alloys) or a nano-coating of conductive noble metal oxides (such as ruthenium-iridium oxide) on the surface of a porous metal transport layer to achieve acid corrosion resistance and oxidation resistance.

[0005] However, while electroless plating can deposit noble metal nanoparticles on different substrates, the process requires strict control of the reaction rate, resulting in slow coating formation. Furthermore, the porous metal substrate is in complete contact with the plating solution, leading to poor coating selectivity and making it impossible to achieve single-sided noble metal deposition, thus hindering the reduction of noble metal loading. Electrochemical plating is simple, but its efficiency is low, adhesion is poor, and single-sided plating is not possible, resulting in material waste. While PVD and CVD technologies can achieve single-sided deposition of noble metal nanolayers, their equipment is expensive, sputtering requires a vacuum environment, precious metal target material is wasted, and large-size substrates cannot be processed, making them unsuitable for large-scale production.

[0006] It is evident that current conventional methods cannot achieve the large-scale, low-cost preparation of single-sided precious metal coatings. Summary of the Invention

[0007] In view of this, this application provides a method for preparing a porous transport composite layer, a porous transport composite layer and its application, aiming to improve the problems of high cost and inability to mass-produce existing porous transport layers with coatings on only one side.

[0008] The embodiments of this application are implemented as follows: A method for preparing a porous transport composite layer includes the following steps:

[0009] A porous transport substrate is provided, the porous transport substrate including a surface to be plated;

[0010] The porous transport substrate is placed in a hydrophobic material and immersed, so that the surface of the porous transport substrate is covered by the hydrophobic material and the pores of the porous transport substrate are filled and covered by the hydrophobic material.

[0011] Remove the hydrophobic material from the surface to be plated on the porous transport substrate to expose the surface to be plated, thus obtaining a first intermediate.

[0012] The first intermediate is placed in an electroplating solution and electroplated to deposit a protective layer on the surface of the porous transport substrate of the first intermediate, thereby obtaining the second intermediate.

[0013] The hydrophobic material on the surface and in the pores of the porous transport substrate of the second intermediate is removed to obtain a porous transport composite layer.

[0014] Optionally, in some embodiments of this application, the porous transport substrate includes one or more of the following: titanium felt, stainless steel fiber sintered felt, copper fiber sintered felt, nickel fiber sintered felt, sintered titanium, copper foam, and nickel foam; and / or

[0015] The hydrophobic material includes one or more of the following: paraffin wax, silane coupling agent, octadecanoic acid, lauric acid, palmitic acid, polyolefin, polycarbonate, polycaprolactone, and polytrimethylene carbonate.

[0016] Optionally, in some embodiments of this application, during the immersion process of the porous transport substrate in the hydrophobic material, the hydrophobic material is in a molten state; and / or

[0017] The soaking time is 30–120 seconds; and / or

[0018] The soaking temperature is 50–95°C.

[0019] Optionally, in some embodiments of this application, the method for removing the hydrophobic material from the surface to be plated on the porous transport substrate includes: first scraping off the hydrophobic material from the surface to be plated, and then cleaning it with a first detergent or polishing the surface to be plated using a polishing machine; and / or

[0020] The method for removing hydrophobic material from the surface and pores of the porous transport substrate of the second intermediate includes cleaning with a second detergent.

[0021] Optionally, in some embodiments of this application, the first detergent includes one or more of petroleum ether, cyclohexane, n-hexane, gasoline, carbon disulfide, xylene, diethyl ether, benzene, chloroform, carbon tetrachloride, naphtha, acetone, ethanol, toluene, tetrahydrofuran, and dichloromethane; and / or

[0022] The second detergent includes one or more of the following: petroleum ether, cyclohexane, n-hexane, gasoline, carbon disulfide, xylene, diethyl ether, benzene, chloroform, carbon tetrachloride, naphtha, acetone, ethanol, toluene, tetrahydrofuran, and dichloromethane.

[0023] Optionally, in some embodiments of this application, the electroplating solution includes a noble metal precursor, a supporting electrolyte, and a leveling agent.

[0024] Optionally, in some embodiments of this application, the noble metal precursor includes one or more of chloroplatinic acid, dinitrosodiammineplatinum, potassium hexahydroxyplatinate, potassium chloroplatinate, iridium trichloride, and iridium tetrachloride; and / or

[0025] The supporting electrolyte includes one or more of sulfuric acid, hydrochloric acid, nitric acid, perchloric acid, sodium hydroxide, and potassium hydroxide; and / or

[0026] The leveling agent comprises one or more of citric acid, o-benzoyl sulfonamide, sodium hexadecyl sulfate, sodium lauryl sulfate, sodium laurylbenzene sulfonate, p-aminobenzene sulfonic acid, aminosulfonic acid, and monosodium glutamate; and / or

[0027] The molar concentration of the noble metal precursor is 5–20 mmol / L; and / or

[0028] The molar concentration of the supporting electrolyte is 0.01–0.5 mol / L; and / or

[0029] The mass concentration of the leveling agent is 0.1–10 mg / L.

[0030] Optionally, in some embodiments of this application, the electroplating current density is 5–30 mA / cm². 2 ; and / or

[0031] The electroplating time is 180–300 seconds; and / or

[0032] The electroplating process also includes nitrogen bubbling treatment on the surface of the porous transport substrate of the first intermediate to be plated.

[0033] Accordingly, this application also provides a porous transport composite layer, which is prepared by the above-described preparation method.

[0034] Accordingly, this application also provides an electrolytic cell, the electrolytic cell comprising a porous transport composite layer prepared by the above preparation method.

[0035] Accordingly, this application also provides an electrochemical hydrogen pump, which includes a porous transport composite layer prepared by the above-described preparation method.

[0036] The method for preparing the porous transport composite layer provided in this application first treats the porous transport substrate with a hydrophobic material. Due to the low surface tension of the hydrophobic material, it penetrates into the pores and surface of the porous transport substrate. After cooling and solidifying, the hydrophobic material fills the pores of the porous transport substrate and covers its surface. The hydrophobic material on the surface to be plated is then removed, exposing the surface to be plated. A protective layer is then plated on the surface to be plated. Due to the superhydrophobic properties of the hydrophobic material, only the surface to be plated in the porous transport substrate is conductive. Therefore, during the plating process, the electroplating solution cannot penetrate into the interior of the porous transport substrate and can only electrodeposit on the surface to be plated, forming a dense protective layer. This achieves selective plating of a protective layer on one side of the porous transport substrate, saving material usage and reducing production costs. Furthermore, the preparation method of this application is simple, requires inexpensive electroplating equipment, and the electroplating process is easy to scale up, making it suitable for large-scale production. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a flowchart of the preparation method of the porous transport composite layer provided in the embodiments of this application;

[0039] Figure 2 This is a scanning electron microscope image of the platinum-plated surface of the single-sided platinum-plated titanium felt provided in Embodiment 1 of this application;

[0040] Figure 3 This is a scanning electron microscope backscattering image of the platinum-plated surface of the single-sided platinum-plated titanium felt provided in Embodiment 1 of this application;

[0041] Figure 4 This is a scanning electron microscope image of the non-platinum-plated side of the single-sided platinum-plated titanium felt provided in Embodiment 1 of this application;

[0042] Figure 5This is a scanning electron microscope image of the platinum-plated surface of the single-sided platinum-plated stainless steel felt provided in Embodiment 2 of this application;

[0043] Figure 6 This is a scanning electron microscope backscattering image of the platinum-plated surface of the single-sided platinum-plated stainless steel felt provided in Embodiment 2 of this application;

[0044] Figure 7 This is a scanning electron microscope image of the non-platinum-plated side of the single-sided platinum-plated stainless steel felt provided in Embodiment 2 of this application;

[0045] Figure 8 These are the polarization curves of the proton membrane water electrolysis devices provided in Application Example 1 and Application Comparative Example 1 of this application;

[0046] Figure 9 These are the stability curves of the proton membrane electrolysis devices provided in Application Example 1 and Application Comparative Example 1 of this application;

[0047] Figure 10 These are the polarization curves of the proton membrane electrolysis devices provided in Application Example 2 and Application Comparative Example 2 of this application;

[0048] Figure 11 These are the stability curves of the proton membrane electrolysis devices provided in Application Example 2 and Application Comparative Example 2 of this application. Detailed Implementation

[0049] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0050] In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its actual use or operating state, specifically the orientation shown in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative purposes and do not impose numerical requirements or establish a numerical order.

[0051] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0052] In this application, "at least one" means one or more, and "more than one" means two or more. "One or more", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0053] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0054] The technical solution of this application is as follows:

[0055] Please see Figure 1 This application provides a method for preparing a porous transport composite layer, comprising the following steps:

[0056] Step S11: Provide a porous transport substrate, wherein the porous transport substrate includes a surface to be plated;

[0057] Step S12: Place the porous transport substrate in a hydrophobic material and immerse it so that the surface of the porous transport substrate is covered by the hydrophobic material and the pores of the porous transport substrate are filled and covered by the hydrophobic material.

[0058] Step S13: Remove the hydrophobic material from the surface to be plated on the porous transport substrate to expose the surface to be plated, thus obtaining the first intermediate.

[0059] Step S14: Place the first intermediate in an electroplating solution and electroplat it to electroplat a protective layer on the surface of the porous transport substrate of the first intermediate to be plated, thereby obtaining the second intermediate;

[0060] Step S15: Remove the hydrophobic material from the surface and pores of the porous transport substrate of the second intermediate to obtain a porous transport composite layer.

[0061] The method for preparing the porous transport composite layer provided in this application first treats the porous transport substrate with a hydrophobic material. Due to the low surface tension of the hydrophobic material, it penetrates into the pores and surface of the porous transport substrate. After cooling and solidifying, the hydrophobic material fills the pores of the porous transport substrate and covers its surface. The hydrophobic material on the surface to be plated is then removed, exposing the surface to be plated. A protective layer is then plated on the surface to be plated. Due to the superhydrophobic properties of the hydrophobic material, only the surface to be plated in the porous transport substrate is conductive. Therefore, during the plating process, the electroplating solution cannot penetrate into the interior of the porous transport substrate and can only electrodeposit on the surface to be plated, forming a dense protective layer. This achieves selective plating of a protective layer on one side of the porous transport substrate, saving material usage and reducing production costs. Furthermore, the preparation method of this application is simple, requires inexpensive electroplating equipment, and the electroplating process is easy to scale up, making it suitable for large-scale production.

[0062] In step S11:

[0063] In some embodiments, the porous transport substrate is a degreased porous transport substrate. It is understood that during storage, handling, and processing, the surface of the porous transport substrate inevitably becomes contaminated with external oil. Degreasing effectively removes the oil from the surface of the porous transport substrate, facilitating subsequent processing.

[0064] In some embodiments, the degreasing method includes one or more of immersion degreasing, spray degreasing, brush degreasing, and ultrasonic degreasing. In at least one embodiment, the degreasing method includes placing the porous transport substrate in an ethanol solution and sonicating for 30 minutes, followed by sonicating in ultrapure water for 30 minutes.

[0065] In some embodiments, the porous transport substrate includes one or more of titanium felt, stainless steel fiber sintered felt, copper fiber sintered felt, nickel fiber sintered felt, sintered titanium, foamed copper, and foamed nickel.

[0066] In step S12:

[0067] In some embodiments, the hydrophobic material includes one or more of paraffin wax, silane coupling agent, octadecanoic acid, lauric acid, palmitic acid, polyolefin, polycarbonate, polycaprolactone, and polytrimethylene carbonate.

[0068] In some embodiments, during the immersion process of the porous transport substrate in a hydrophobic material, the hydrophobic material is in a molten state.

[0069] In some embodiments, the porous transport substrate is immersed in the hydrophobic material for 30–120 seconds, for example, 40–110 seconds, 50–100 seconds, 55–95 seconds, 60–90 seconds, 70–80 seconds, etc. This allows the surface of the porous transport substrate to be effectively covered by the hydrophobic material, and the pores of the porous transport substrate to be effectively filled by the hydrophobic material.

[0070] In some embodiments, the porous transport substrate is immersed in the hydrophobic material at a temperature of 50–95°C, for example, 52–92°C, 55–90°C, 58–88°C, 60–80°C, 70–75°C, etc. Within this temperature range, it is beneficial for the hydrophobic material to fully fill the pores of the porous transport substrate and cover its surface.

[0071] In step S13:

[0072] In some embodiments, the method for removing the hydrophobic material from the surface to be plated of the porous transport substrate includes: first scraping off the hydrophobic material from the surface to be plated, and then cleaning with a first detergent or polishing the surface to be plated with a polishing machine. It is understood that when cleaning with the first detergent, a lint-free cloth dampened with the first detergent can be used to wipe the hydrophobic material from the surface to be plated.

[0073] In some embodiments, the first detergent comprises one or more of petroleum ether, cyclohexane, n-hexane, gasoline, carbon disulfide, xylene, diethyl ether, benzene, chloroform, carbon tetrachloride, naphtha, acetone, ethanol, toluene, tetrahydrofuran, and dichloromethane.

[0074] In some embodiments, after obtaining the first intermediate, the method further includes removing impurities from the surface of the porous transport substrate of the first intermediate to be plated.

[0075] In some embodiments, the method for removing impurities from the surface of the porous transport substrate to be plated of the first intermediate includes etching. It is understood that during production, transportation, and storage, the surface of the porous transport substrate inevitably contains some impurities, such as oxide layers, hardened surfaces, decarburized layers, porous layers, and corrosion products. Etching can effectively remove these impurities from the surface to be plated.

[0076] In some embodiments, the etching includes immersing the first intermediate in an etching solution.

[0077] In some embodiments, the etching solution includes one or more of hydrofluoric acid, nitric acid, sulfuric acid, perchloric acid, hydrochloric acid, and oxalic acid. It is understood that when the etching solution includes hydrofluoric acid, the container used for etching is a polytetrafluoroethylene (PTFE) container to avoid corrosion of the container by the hydrofluoric acid.

[0078] In at least one embodiment, when the porous transport substrate is a titanium felt, the etching solution comprises water, hydrofluoric acid, and nitric acid in a volume ratio of 100:1:3, wherein the mass fraction of the hydrofluoric acid is 40% and the mass fraction of the nitric acid is 68%.

[0079] In at least one embodiment, when the porous transport substrate is a stainless steel fiber sintered felt, the etching solution includes sulfuric acid, and the molar concentration of the sulfuric acid is 0.5 mol / L.

[0080] In some embodiments, the immersion time of the first intermediate in the etching solution is 1–30 min, for example, 2–28 min, 5–25 min, 8–20 min, 10–18 min, 12–15 min, etc. Within the immersion time range, the porous metal transport substrate is pretreated to improve the adhesion between the protective layer and the porous transport substrate.

[0081] In some embodiments, after etching, the first intermediate of the etching process is further subjected to cleaning and drying.

[0082] In some embodiments, the etching process further includes an activation treatment. This activation can introduce new active groups into the surface to be plated after impurities have been removed, improving the wettability and adhesion of the surface, and facilitating a strong bond between the protective layer and the porous transport substrate.

[0083] In some embodiments, the activation includes immersing the etched first intermediate in an activation solution.

[0084] In some embodiments, the activation solution includes an acidic solution, wherein the acid in the acidic solution includes one or more of hydrofluoric acid, nitric acid, hydrochloric acid, and sulfuric acid. The acidic solution is an aqueous solution of an acidic compound. It is understood that when the activation solution includes a hydrofluoric acid solution, the container used for activation is a polytetrafluoroethylene (PTFE) container to avoid corrosion of the container by the hydrofluoric acid.

[0085] In some embodiments, the acid in the acidic solution has a mass fraction of 1% to 40%, for example, it can be 1% to 40%, 1% to 40%, 1% to 40%, 1% to 40%, 1% to 40%, etc. Within this mass fraction range, the acidic solution is beneficial for activating the first intermediate and promoting the bonding of the protective layer to the porous transport substrate.

[0086] In some embodiments, the activation solution further includes a solvent, which includes one or more of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), acetonitrile, dimethyl sulfoxide (DMSO), acetone, and hexamethylphosphoric triamine (HMPA).

[0087] In some embodiments, the activation solution is prepared by mixing the acidic solution and the solvent in a volume ratio of 1:(1-20), for example, 1:(2-18), 1:(3-16), 1:(5-15), 1:(8-12), 1:(10-11), etc. Within this range, the activation solution has a good activation effect, effectively improving the wetting performance and adhesion of the surface to be plated, which is beneficial to the firm bonding of the protective layer and the porous transport substrate.

[0088] In some embodiments, the immersion time of the etched first intermediate in the activation solution is 1–10 min, for example, 2–9 min, 3–7 min, 4–6 min, 5–5.5 min, etc. Within this immersion time range, it is beneficial for the first intermediate to be fully activated, promoting a strong bond between the protective layer and the porous transport substrate.

[0089] In step S14:

[0090] In some embodiments, the electroplating solution includes a noble metal precursor, a supporting electrolyte, and a leveling agent. The noble metal precursor can serve as a source of the noble metal; the supporting electrolyte can promote the dissolution of the noble metal precursor, increase the conductivity of the solution, enhance the dispersion ability of the electroplating solution, and accelerate the electroplating speed; the leveling agent can improve the density of the protective layer and enhance the corrosion resistance of the obtained protective layer.

[0091] In some embodiments, the noble metal precursor includes one or more of chloroplatinic acid, potassium chloroplatinate, potassium hexahydroxyplatinate, dinitrosoplatinum, iridium trichloride, and iridium tetrachloride.

[0092] In some embodiments, the noble metal precursor is chloroplatinic acid. Choosing a chloroplatinic acid plating solution eliminates the complex step of preparing the main salt in platinum salt plating processes, further reducing the amount of noble metal platinum used.

[0093] In some embodiments, the molar concentration of the noble metal precursor is 5–20 mmol / L, for example, it can be 6–19 mmol / L, 7–18 mmol / L, 8–17 mmol / L, 9–16 mmol / L, 10–15 mmol / L, 11–14 mmol / L, 12–13 mmol / L, etc. Within this molar concentration range, it is beneficial to increase the deposition rate of the noble metal and promote the efficiency of the electroplated protective layer, fully and effectively utilizing the noble metal and saving costs.

[0094] In some embodiments, the supporting electrolyte includes one or more of sulfuric acid, hydrochloric acid, nitric acid, perchloric acid, sodium hydroxide, and potassium hydroxide.

[0095] In some embodiments, the molar concentration of the supporting electrolyte is 0.01–0.5 mol / L, for example, it can be 0.05–0.45 mol / L, 0.1–0.4 mol / L, 0.15–0.35 mol / L, 0.2–0.3 mol / L, 0.25–0.28 mol / L, etc. Within this molar concentration range, the supporting electrolyte is beneficial in promoting the dissolution of the noble metal precursor.

[0096] In some embodiments, the leveling agent includes one or more of citric acid, o-benzoylsulfonylimide, sodium hexadecyl sulfate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, p-aminobenzenesulfonic acid, aminosulfonic acid, and monosodium glutamate.

[0097] In some embodiments, the mass concentration of the leveling agent is 0.1–10 mg / L, for example, it can be 1–9 mg / L, 2–8 mg / L, 3–7 mg / L, 4–6 mg / L, 4.5–5 mg / L, etc. Within the mass concentration range, a denser and more uniform anti-corrosion layer can be obtained, improving the corrosion resistance of the obtained anti-corrosion layer.

[0098] It is understood that appropriate amounts of commonly used additives, such as wetting agents, coating refiners, brighteners, and buffers, may be added to the electroplating solution as needed.

[0099] In some embodiments, the current density of the electroplating is 5–30 mA / cm². 2 For example, it can be 8-28 mA / cm 2 10~26mA / cm 2 12~25mA / cm 2 15~22mA / cm 2 18~20mA / cm 2 Within the current density range of the electroplating process, the electroplating conditions are mild, which is conducive to the effective deposition of a protective layer.

[0100] In some embodiments, the electroplating time is 180–300 s, for example, 190–290 s, 200–280 s, 210–270 s, 220–260 s, 230–240 s, etc. Within the specified electroplating time range, the electroplating solution can be fully utilized, avoiding waste.

[0101] In some embodiments, the electroplating process further includes nitrogen bubbling treatment of the surface of the porous transport substrate of the first intermediate to be plated. The nitrogen bubbling treatment removes oxygen, preventing oxidation of the surface of the porous transport substrate of the first intermediate; it also removes hydrogen generated on the electrode surface, which facilitates electroplating on the electrode surface, improves the quality of contact between the precious metal and the surface of the porous transport substrate of the first intermediate, and enhances the corrosion resistance of the protective layer.

[0102] In step S15:

[0103] In some embodiments, the method for removing hydrophobic material from the surface and pores of the porous transport substrate of the second intermediate includes cleaning with a second detergent.

[0104] In some embodiments, the second detergent comprises one or more of petroleum ether, cyclohexane, n-hexane, gasoline, carbon disulfide, xylene, diethyl ether, benzene, chloroform, carbon tetrachloride, naphtha, acetone, ethanol, toluene, tetrahydrofuran, and dichloromethane.

[0105] In some embodiments, after obtaining the porous transport composite layer, ultrasonic treatment is further included. The ultrasonic treatment time is 5–30 min, for example, 6–28 min, 8–25 min, 10–22 min, 12–20 min, 15–18 min, etc.; the ultrasonic treatment environment is at least one of ethanol and ultrapure water. The ultrasonic treatment can further remove the hydrophobic material of the porous transport composite layer and improve the performance of the porous transport composite layer.

[0106] In at least one embodiment, the porous transport composite layer is ultrasonically treated in ethanol for 10 minutes, and then ultrasonically treated in ultrapure water for 10 minutes.

[0107] Secondly, this application also provides a porous transport composite layer prepared by the above-described preparation method.

[0108] In some embodiments, the porous transport composite layer includes a porous transport substrate, and a protective layer is deposited on one side of the porous transport substrate.

[0109] The porous transmission composite layer described in this application has a protective layer coated on one side of the porous transmission substrate, which can save on the amount of material used for the protective layer and reduce costs.

[0110] Thirdly, this application also provides an application of the porous transport composite layer prepared by the above preparation method in water electrolysis for hydrogen production, the application including but not limited to electrolyzers and electrochemical hydrogen pumps.

[0111] The application described in this application employs a porous transport composite layer with a protective layer plated on one side. This porous transport composite layer functions as both an electrical conductor and a water vapor transporter, while the single-sided protective layer prevents the porous transport composite layer from releasing metal ions after acid etching. This avoids metal ion poisoning of the proton exchange membrane and induction of Fenton-like reactions, which would otherwise lead to decreased electrolysis efficiency and reduced durability in the water electrolysis device. The single-sided protective layer requires a small amount of precious metal, resulting in low processing costs. The application provided in this application, such as in a water electrolysis device, exhibits high electrolysis efficiency and durability, making it suitable for large-scale production and use.

[0112] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0113] Example 1

[0114] This embodiment provides a porous transport composite layer, the preparation method of which includes:

[0115] Unplated platinum-titanium felt is provided, and it is placed in an ethanol solution and sonicated for 30 minutes, then placed in ultrapure water and sonicated for 30 minutes to clean and remove oil.

[0116] The titanium felt is placed in molten paraffin heated to above 60°C and soaked for 30 seconds. After the paraffin solidifies, the paraffin on one side of the titanium felt is removed with a scraper and treated with petroleum ether 60-90 until the metal surface of that side is exposed.

[0117] Add 10 mL of concentrated HF (40 wt%) and 30 mL of concentrated HNO3 (68 wt%) to 1 L of ultrapure water to prepare an etching solution. Mix concentrated HF (40 wt%) and N,N-dimethylformamide at a volume ratio of 2:8 to prepare an activation solution. Place the above paraffin-treated titanium felt in the etching solution in a polytetrafluoroethylene container, soak for 5 min, remove it, wash with ultrapure water and blow dry, and then quickly transfer it to the activation solution to soak for 2 min to remove the surface of the hydrophobic material and form a black titanium hydride nanolayer.

[0118] An electroplating solution is provided, comprising 5 mmol / L chloroplatinic acid, 0.5 mol / L sulfuric acid, and 1 mg / L citric acid. The pre-treated titanium felt is placed in the electroplating solution as a cathode, and the current density is controlled at 10 mA / cm². 2 Electroplating is performed for 300 seconds. During the electroplating process, nitrogen gas is bubbled onto the surface of the titanium felt to remove paraffin.

[0119] The electroplated titanium felt was rinsed with deionized water and dried. It was then ultrasonically cleaned in petroleum ether 60-90 until the paraffin was completely dissolved and removed. After that, it was ultrasonically cleaned in ethanol and ultrapure water for 10 minutes each and then dried to obtain a single-sided electroplated platinum titanium felt.

[0120] Example 2

[0121] This embodiment is basically the same as Embodiment 1, except that the unplated platinum titanium felt is replaced with unplated platinum stainless steel felt, the etching solution is replaced with 0.5 mol / L sulfuric acid, and the etching time is 20 min, finally obtaining a single-sided platinum stainless steel felt.

[0122] Example 3

[0123] This embodiment is basically the same as Embodiment 2, except that stainless steel felt is replaced with nickel felt in this embodiment.

[0124] Example 4

[0125] This embodiment is basically the same as embodiment 2, except that the stainless steel felt is replaced with copper felt in this embodiment.

[0126] Example 5

[0127] This embodiment is basically the same as Embodiment 1, except that paraffin is replaced with lauric acid in this embodiment.

[0128] Example 6

[0129] This embodiment is basically the same as Embodiment 1, except that the soaking time in paraffin is 80 seconds in this embodiment.

[0130] Example 7

[0131] This embodiment is basically the same as Embodiment 1, except that the soaking time in paraffin is 120 seconds in this embodiment.

[0132] Scanning electron microscopy (SEM) was performed on the platinum-plated surface of the single-sided electroplated platinum-titanium felt in Example 1, and the SEM image of the platinum-plated surface of the single-sided electroplated platinum-titanium felt is shown below. Figure 2 As shown, the backscattering image of the platinum-plated surface of the single-sided electroplated platinum-titanium felt obtained by scanning electron microscopy is as follows. Figure 3 As shown.

[0133] Depend on Figure 2 and Figure 3 As can be seen, the bright areas in the figure are platinum plating layers. Platinum nanoparticles aggregate on the surface of the titanium felt to form a dense plating layer. Due to the paraffin coating, no nanoparticles are deposited inside the titanium felt.

[0134] Scanning electron microscopy (SEM) was performed on the unplated surface of the single-sided electroplated platinum-titanium felt from Example 1, and the SEM image of the unplated surface of the single-sided electroplated platinum-titanium felt is shown below. Figure 4 As shown.

[0135] Depend on Figure 4 It can be seen that during the platinum plating process, the paraffin-coated titanium felt is smooth on one side and inside, with no platinum nanoparticles deposited.

[0136] Scanning electron microscopy (SEM) was performed on the platinum-plated surface of the single-sided platinum-plated stainless steel felt in Example 2, and the SEM image of the platinum-plated surface of the single-sided platinum-plated stainless steel felt is shown below. Figure 5 As shown, the backscattering image of the platinum-plated surface of the single-sided platinum-plated stainless steel felt obtained by scanning electron microscopy is as follows. Figure 6 As shown.

[0137] Depend on Figure 5 and Figure 6 As can be seen, the bright areas in the figure are platinum plating layers. Platinum nanoparticles aggregate on the surface of the stainless steel felt to form a dense plating layer. Due to the paraffin coating, no nanoparticles are deposited inside the stainless steel felt.

[0138] Scanning electron microscopy (SEM) was performed on the unplated surface of the single-sided platinum-plated stainless steel felt in Example 2. The SEM image of the unplated surface of the single-sided platinum-plated stainless steel felt is shown below. Figure 7 As shown.

[0139] Depend on Figure 7 It can be seen that during the platinum plating process, the paraffin-coated stainless steel felt and the interior of the titanium felt are smooth, with no platinum nanoparticles deposited.

[0140] Application Example 1

[0141] Using the single-sided electroplated platinum-titanium felt from Example 1 as a porous transport layer, a proton membrane water electrolysis device was prepared.

[0142] Application Examples 2-7

[0143] Using the porous transport composite layers of Examples 2-7 as porous transport layers, a proton membrane water electrolysis device was prepared.

[0144] Application Comparative Example 1

[0145] Using the unplated platinum-titanium felt from Example 1 as a porous transport layer, a proton membrane water electrolysis device was prepared.

[0146] Application Comparative Example 2

[0147] Using the unplated platinum stainless steel felt from Example 2 as a porous transport layer, a proton membrane water electrolysis device was prepared.

[0148] The polarization curves and stability of the proton exchange membrane water electrolyzers used in Examples 1-2 and Comparative Examples 1-2 were measured during hydrogen production operation, respectively. The polarization curves of the proton exchange membrane water electrolyzers used in Example 1 and Comparative Example 1 are shown below. Figure 8 As shown, the stability curves of the proton membrane water electrolysis device of Application Example 1 and the proton membrane water electrolysis device of Comparative Example 1 are as follows: Figure 9 As shown; the polarization curves of the proton membrane electrolysis device of Application Example 2 and the proton membrane electrolysis device of Comparative Example 2 are obtained as follows. Figure 10 As shown, the stability curves of the proton membrane water electrolysis device in Application Example 2 and the proton membrane water electrolysis device in Comparative Example 2 are as follows: Figure 11 As shown.

[0149] The polarization curve and stability were tested under the following conditions: the anode catalyst was pure-phase iridium oxide (iridium loading 1.0 mg / cm³). 2 The cathode catalyst is platinum-carbon (platinum loading of 0.3 mg / cm³). 2 The proton exchange membrane used was a DuPont Nafion 115 membrane, and the test current density was 2 A / cm². 2 The test temperature was 80℃.

[0150] Depend on Figure 8 It can be seen that as the current density increases, the cell voltage of both the proton membrane electrolysis device in Example 1 and the proton membrane electrolysis device in Comparative Example 1 shows an upward trend. Under the same current density, the cell voltage of the proton membrane electrolysis device in Example 1 is always lower than that of the proton membrane electrolysis device in Comparative Example 1, which is more conducive to meeting the working conditions of the proton membrane electrolyzer.

[0151] Depend on Figure 9 It can be seen that as the running time increases, the cell pressure of the proton membrane electrolysis device in Example 1 only increases slowly and tends to be stable overall, while the cell pressure of the proton membrane electrolysis device in Comparative Example 1 shows a significant upward trend. Under the same current density, the cell pressure of the proton membrane electrolysis device in Example 1 is always lower than that of the proton membrane electrolysis device in Comparative Example 1, indicating that the electrolysis device in Example 1 is more stable.

[0152] Depend on Figure 10 It can be seen that as the current density increases, the cell voltage of both the proton membrane electrolysis device in Application Example 2 and the proton membrane electrolysis device in Comparative Example 2 shows an upward trend. Under the same current density, the cell voltage of the proton membrane electrolysis device in Application Example 2 is always lower than that of the proton membrane electrolysis device in Comparative Example 2, which is more conducive to meeting the working conditions of the proton membrane electrolyzer.

[0153] Depend on Figure 11 It can be seen that as the running time increases, the cell voltage of the proton membrane electrolysis device in Application Example 2 tends to stabilize, while the cell voltage of the proton membrane electrolysis device in Comparative Example 2 shows a significant upward trend. Under the same current density, the cell voltage of the proton membrane electrolysis device in Application Example 2 is always less than the overpotential of the proton membrane electrolysis device in Comparative Example 2, indicating that the electrolysis device in Application Example 2 has higher stability.

[0154] The preparation method of the porous transport composite layer, the porous transport composite layer and its application provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for preparing a porous transport composite layer, characterized in that, Includes the following steps: A porous transport substrate is provided, the porous transport substrate including a surface to be plated; The porous transport substrate is placed in a hydrophobic material and immersed, so that the surface of the porous transport substrate is covered by the hydrophobic material and the pores of the porous transport substrate are filled and covered by the hydrophobic material. Remove the hydrophobic material from the surface to be plated on the porous transport substrate to expose the surface to be plated, thus obtaining a first intermediate. The first intermediate is placed in an electroplating solution and electroplated to deposit a protective layer on the surface of the porous transport substrate of the first intermediate to be plated, thereby obtaining the second intermediate. The hydrophobic material on the surface and in the pores of the porous transport substrate of the second intermediate is removed to obtain a porous transport composite layer.

2. The preparation method according to claim 1, characterized in that, The porous transport substrate includes one or more of the following: titanium felt, stainless steel fiber sintered felt, copper fiber sintered felt, nickel fiber sintered felt, sintered titanium, foamed copper, and foamed nickel. The hydrophobic material includes one or more of the following: paraffin wax, silane coupling agent, octadecanoic acid, lauric acid, palmitic acid, polyolefin, polycarbonate, polycaprolactone, and polytrimethylene carbonate.

3. The preparation method according to claim 1, characterized in that, During the immersion process of the porous transport substrate in the hydrophobic material, the hydrophobic material is in a molten state. The soaking time is 30~120 s; The soaking temperature is 50–95°C.

4. The preparation method according to claim 1, characterized in that, The method for removing hydrophobic material from the surface to be plated of the porous transport substrate includes: first scraping off the hydrophobic material from the surface to be plated, and then cleaning it with a first detergent or polishing the surface to be plated with a polishing machine; The method for removing hydrophobic material from the surface and pores of the porous transport substrate of the second intermediate includes cleaning with a second detergent.

5. The preparation method according to claim 4, characterized in that, The first detergent includes one or more of the following: petroleum ether, cyclohexane, n-hexane, gasoline, carbon disulfide, xylene, diethyl ether, benzene, chloroform, carbon tetrachloride, naphtha, acetone, ethanol, toluene, tetrahydrofuran, and dichloromethane. The second detergent includes one or more of the following: petroleum ether, cyclohexane, n-hexane, gasoline, carbon disulfide, xylene, diethyl ether, benzene, chloroform, carbon tetrachloride, naphtha, acetone, ethanol, toluene, tetrahydrofuran, and dichloromethane.

6. The preparation method according to claim 1, characterized in that, The electroplating solution includes a precious metal precursor, a supporting electrolyte, and a leveling agent.

7. The preparation method according to claim 6, characterized in that, The noble metal precursor includes one or more of chloroplatinic acid, dinitrosodiammineplatinum, potassium hexahydroxyplatinate, potassium chloroplatinum, iridium trichloride, and iridium tetrachloride. The supporting electrolyte includes one or more of sulfuric acid, hydrochloric acid, nitric acid, perchloric acid, sodium hydroxide, and potassium hydroxide; The leveling agent includes one or more of citric acid, o-benzoyl sulfonamide, sodium hexadecyl sulfate, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, p-aminobenzene sulfonic acid, aminosulfonic acid, and monosodium glutamate. The molar concentration of the noble metal precursor is 5~20 mmol / L; The molar concentration of the supporting electrolyte is 0.01–0.5 mol / L; The mass concentration of the leveling agent is 0.1~10 mg / L.

8. The preparation method according to claim 1, characterized in that, The current density for electroplating is 5~30 mA / cm². 2 ; The electroplating time is 180~300 s; The electroplating process also includes nitrogen bubbling treatment on the surface of the porous transport substrate of the first intermediate to be plated.

9. A porous transport composite layer, characterized in that, The porous transport composite layer is prepared by the preparation method according to any one of claims 1 to 8.

10. An electrolytic cell, characterized in that, The electrolytic cell includes a porous transport composite layer prepared by the preparation method according to any one of claims 1 to 8.

11. An electrochemical hydrogen pump, characterized in that, The electrochemical hydrogen pump comprises a porous transport composite layer prepared by the preparation method according to any one of claims 1 to 8.

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