Anode catalyst layer for water electrolysis membrane electrode, manufacturing method therefor, and membrane electrode

Abstract

An anode catalyst layer for a water electrolysis membrane electrode, consisting of N sub-layers; each sub-layer contains an anode catalyst and an ionomer, the anode catalyst being selected from one or a combination of two of a supported iridium oxide catalyst and a ruthenium iridium terbium catalyst; from the first sub-layer to the N-th sub-layer, the Ir content gradually increases and the ionomer content gradually decreases. A membrane electrode manufactured from the anode catalyst layer can reduce the mass transfer resistance of liquid phase, gas phase and protons, thereby achieving the purpose of improving the performance and durability of the membrane electrode.

Description

An anode catalyst layer for a water electrolysis membrane electrode and its preparation method, and the membrane electrode itself.

[0001] Cross-reference information

[0002] This application claims priority to Chinese Patent Application No. 202411537616.2, filed on October 30, 2024, entitled "An Anode Catalyst Layer for Electrolytic Water Membrane Electrode and Its Preparation Method and Membrane Electrode", and Chinese Patent Application No. 202411537821.9, filed on October 30, 2024, entitled "An Anode Catalyst Layer Based on Ruthenium-Iridium-Terbium Catalyst and Its Preparation Method and Membrane Electrode", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to the field of proton exchange membrane electrolysis for hydrogen production, and more specifically, to an anode catalyst composite layer for water electrolysis membrane electrode, its preparation method, and the membrane electrode. Background Technology

[0004] Hydrogen is an energy-rich molecule that is particularly well-suited for energy storage. It can be easily transferred and stored in gas pipeline networks, enabling renewable energy to be efficiently distributed to heating and transportation sectors.

[0005] Hydrogen production via the electrochemical splitting of water will play a crucial role in the large-scale storage and conversion of renewable energy, especially when combined with intermittent renewable energy sources such as wind and solar photovoltaic power. However, the feasibility of large-scale hydrogen production is a prerequisite for implementing large-scale hydrogen energy storage. Proton exchange membrane (PEM) water splitting electrolyzers offer advantages such as fast response and high efficiency, which can greatly meet the requirements of flexible energy storage for wind and solar power.

[0006] Unfortunately, the oxygen evolution reaction (OER), a half-reaction in acidic water electrolysis, requires a large overpotential to drive the slow four-electron process, severely limiting the efficiency of water electrolysis. Therefore, there is an urgent need to develop highly active and stable electrocatalysts for catalyzing the OER process in PEM water splitting electrolyzers. While the relatively low-cost RuO2 can be used as an anode electrode to replace commercial IrO2, it is unstable under harsh corrosive conditions such as high oxidation potential, low pH, and high oxygen concentration, eventually decomposing into soluble RuO4 or H2RuO5.

[0007] Lanthanide ruthenium-based pyrochlore is a mixed metal oxide. Compared with rutile-type RuO2 and perovskite-type ruthenium-based oxides, it has a more stable band structure, exhibits higher OER activity and stability under harsh operating environments of high voltage and strong acidity, and significantly reduces the content of the noble metal Ru. Among a series of ruthenium-based pyrochlores with lanthanide elements at the A-site, due to Ln... 3+ and Ru 4+ Due to favorable exchange interactions, Tb₂Ru₂O₇ exhibits the best activity. However, the durability of Tb₂Ru₂O₇ is still insufficient to meet the needs of large-scale hydrogen production, and its stability needs to be improved.

[0008] The electrolyzer is a key piece of equipment in PEMWE, and includes components such as the membrane electrode assembly (MEA), diffusion layer (also called current collector), and electrode plates. The membrane electrode assembly consists of an anode catalyst, a proton exchange membrane, and a cathode catalyst.

[0009] The stability of a membrane electrode is one of the most important performance indicators, determined by the catalytic layer on its surface. The catalytic layer mainly consists of electrocatalysts, proton-conducting ionomers, and porous structures, and is the core site for electrochemical reactions involving multiphase mass transport and energy conversion.

[0010] The catalyst surface provides the site for the OER reaction. Oxygen and protons are generated on the catalyst surface, while electrons transfer from one catalyst surface to another, eventually converging at the catalyst layer surface. These electrons then leave the electrolytic cell via the metal surface of the gas diffusion layer, reaching the cathode catalyst layer of the membrane electrode assembly (MEA), where they combine with protons on the cathode catalyst surface to form hydrogen. Oxygen enters the pores between the ionomer and the catalyst, gradually moving from the deeper layers of the catalyst layer towards the surface, accumulating and growing in the process. Protons transfer from the catalyst surface to the ionomer surface, transporting through the network formed by the ionomers to the cathode catalyst surface of the other layer of the proton exchange membrane, where they gain electrons and are reduced to hydrogen.

[0011] CN113066999A, CN115425239A, and CN113991125A respectively disclose technical solutions for preparing cathode catalyst layers using ammonium salt pore-forming agents. The prepared cathode catalyst layers have richer pore structures, with wider and larger pore distribution in the nanoscale range. At the same time, a large number of micron-sized pores observed by SEM appear, which reduces the gas transport and liquid discharge resistance of the membrane electrode under high electrical density conditions, thereby improving the working performance of the membrane electrode.

[0012] However, the pore size distribution of the catalyst layer cannot be controlled during the removal process of the above-mentioned pore-forming agent, resulting in the formation of some micropores inside, which is not conducive to the gas discharge. This leads to an increase in interfacial contact resistance, which has an adverse effect on the oxygen evolution catalytic activity. Moreover, the stability of the above-mentioned materials is also low.

[0013] Therefore, developing membrane electrodes that possess both high oxygen evolution catalytic activity and high stability is a problem that urgently needs to be solved in this field. Summary of the Invention

[0014] To address the aforementioned technical problems, the present invention aims to provide an anode catalyst layer for a water electrolysis membrane electrode and a method for preparing the same. This anode catalyst layer has a multilayer structure and provides good stability.

[0015] Another objective of this invention is to provide a membrane electrode based on the above-described anode catalyst layer.

[0016] To achieve the above objectives, the present invention provides an anode catalyst layer for a water electrolysis membrane electrode, wherein the anode catalyst layer for the water electrolysis membrane electrode is composed of N sublayers, where N≥2;

[0017] Each sublayer contains an anolyte catalyst and an ionomer (i.e., an ionomer-based quantum conductor); the anolyte catalyst is selected from one or a combination of two supported iridium oxide catalysts and ruthenium-iridium-terbium catalysts, wherein the ruthenium-iridium-terbium catalyst has a pyrochlore structure and the molecular formula Tb₂Ru. x Ir 2-x O7, where 0 <x<2;

[0018] The Ir content gradually increases from the first sublayer to the Nth sublayer, while the ionomer content gradually decreases.

[0019] According to a specific embodiment of the present invention, preferably, in the above-mentioned anode catalyst layer for water electrolysis membrane electrode, N≥3, that is, the total number of sublayers is 3 or more.

[0020] According to a specific embodiment of the present invention, preferably, in the anode catalyst layer of the above-mentioned water electrolysis membrane electrode, the Ir content of the m-th sublayer is 1-10 times that of the (m-1)-th sublayer, where m is the sublayer number (m≤N), that is, in two adjacent sublayers, the Ir content of the sublayer with the larger number is 1-10 times that of the sublayer with the smaller number.

[0021] According to a specific embodiment of the present invention, preferably, in the above-mentioned anode catalyst layer for water electrolysis membrane electrode, the ionomer content of the m-th sublayer is 0.2-1 times that of the (m-1)-th sublayer, where m is the sublayer number (m≤N), that is, in two adjacent sublayers, the ionomer content of the sublayer with the larger number is 0.2-1 times that of the sublayer with the smaller number.

[0022] According to a specific embodiment of the present invention, preferably, in the usage state, the first sublayer is disposed on the surface of the proton exchange membrane, and from there to the second to the Nth sublayer, the Ir content gradually increases and the ionomer content gradually decreases. That is, when the above-mentioned anode catalyst layer for the water electrolysis membrane electrode is applied to the anode of the water electrolysis membrane electrode, the closer to the proton exchange membrane, the lower the Ir content and the higher the ionomer content in the sublayer. According to a specific embodiment of the present invention, preferably, in the above-mentioned anode catalyst layer for the water electrolysis membrane electrode, the catalyst content of the anode catalyst layer for the water electrolysis membrane electrode is 1.0-4.0 mg / cm², based on the area of ​​the anode catalyst layer. 2 More preferably 2.0-3.0 mg / cm³ 2 .

[0023] According to a specific embodiment of the present invention, preferably, in the above-mentioned anode catalyst layer for water electrolysis membrane electrode, the Ir content of the anode catalyst layer for water electrolysis membrane electrode is 0.1-1.9 mg / cm², based on the area of ​​the anode catalyst layer. 2 More preferably 0.2-1.0 mg / cm³ 2 .

[0024] According to a specific embodiment of the present invention, preferably, in the above-mentioned anode catalyst layer for water electrolysis membrane electrode, the mass ratio of the ionomer to the anode catalyst is 1:1-5, more preferably 1:1-4. The structure and characteristics of the catalyst layer have a significant impact on the activation polarization, concentration polarization, and ohmic polarization of the electrochemical reaction. The amount and distribution of the ionomer, which functions as a proton conductor and binder in the catalyst layer, have a significant impact on the electrolysis performance. Too little ionomer will lead to a decrease in the proton conduction performance of the catalyst layer, while too much ionomer will occupy too much volume in the catalyst layer, reduce the pore permeability, increase the oxygen transport resistance, and lead to a decrease in the conductivity within the catalyst layer and an increase in the contact resistance between the catalyst layer and the diffusion layer. It may even cause the catalyst layer to tear due to the formation of microbubbles caused by oxygen accumulation, resulting in local peeling of the catalyst layer after long-term operation and reduced durability.

[0025] According to a specific embodiment of the present invention, preferably, in the above-mentioned anode catalyst layer for water electrolysis membrane electrode, the support for the supported iridium oxide catalyst is selected from one or more combinations of inert oxides such as TiO2, Nb2O5, and Ta2O5.

[0026] According to a specific embodiment of the present invention, preferably, in the above-mentioned anode catalyst layer for water electrolysis membrane electrode, the anode catalyst is selected from one or more combinations of ruthenium-iridium-terbium catalysts, that is, the anode catalyst used in the anode catalyst layer is all ruthenium-iridium-terbium catalyst, and the anode catalyst in each sublayer is a ruthenium-iridium-terbium catalyst with different Ir contents.

[0027] According to a specific embodiment of the present invention, the ruthenium-iridium-terbium catalyst used in the anode catalyst layer of the above-mentioned water electrolysis membrane electrode has an A2B2O7 structure, i.e., a pyrochlore structure. Preferably, in the molecular formula of the ruthenium-iridium-terbium nanocatalyst, 0.05≤x≤1.95; more preferably, 0.4≤x≤1.6. The ruthenium-iridium-terbium catalyst used in the present invention is ruthenium-based pyrochlore, a mixed metal oxide. Compared with rutile-type RuO2 and perovskite-type ruthenium-based oxides, it has a more stable band structure, exhibits higher oxygen evolution reaction (OER) activity and stability under harsh working environments of high voltage and strong acidity, and can significantly reduce the content of the noble metal Ru.

[0028] According to a specific embodiment of the present invention, preferably, the ruthenium-iridium-terbium nanocatalyst is Tb₂Ru. 1.95 Ir 0.05 O7、Tb2Ru 1.90 Ir 0.10 O7、Tb2Ru 1.85 Ir 0.15 O7、Tb2Ru 1.80 Ir 0.20 O7、Tb2Ru 1.75 Ir 0.25 O7、Tb2Ru 1.70 Ir 0.30 O7、Tb2Ru 1.65 Ir 0.35 O7、Tb2Ru 1.60 Ir 0.40 O7、Tb2Ru 1.55 Ir 0.45 O7、Tb2Ru 1.50 Ir 0.50 O7、Tb2Ru 1.45 Ir 0.55 O7、Tb2Ru 1.40 Ir 0.60 O7、Tb2Ru 1.35 Ir 0.65 O7、Tb2Ru 1.30 Ir 0.70 O7、Tb2Ru 1.25 Ir 0.75 O7、Tb2Ru 1.20 Ir 0.80 O7、Tb2Ru 1.15 Ir 0.85 O7、Tb2Ru 1.10 Ir 0.90 O7、Tb2Ru 1.05 Ir 0.95 O7、Tb2Ru 1.00Ir 1.00 O7、Tb2Ru 0.95 Ir 1.05 O7、Tb2Ru 0.90 Ir 1.10 O7、Tb2Ru 0.85 Ir 1.15 O7、Tb2Ru 0.80 Ir 1.20 O7、Tb2Ru 0.75 Ir 1.25 O7、Tb2Ru 0.70 Ir 1.30 O7、Tb2Ru 0.65 Ir 1.35 O7、Tb2Ru 0.60 Ir 1.40 O7、Tb2Ru 0.55 Ir 1.45 O7、Tb2Ru 0.50 Ir 1.50 O7、Tb2Ru 0.45 Ir 1.55 O7、Tb2Ru 0.40 Ir 1.60 O7、Tb2Ru 0.35 Ir 1.65 O7、Tb2Ru 0.30 Ir 1.70 O7、Tb2Ru 0.25 Ir 1.75 O7、Tb2Ru 0.20 Ir 1.80 O7、Tb2Ru 0.15 Ir 1.85 O7、Tb2Ru 0.10 Ir 1.90 O7、Tb2Ru 0.05 Ir 1.95 At least one of O7.

[0029] According to a specific embodiment of the present invention, preferably, the ruthenium-iridium-terbium catalyst is particulate with a particle size of 40-180 nm, more preferably, with a particle size of 60-80 nm. Ruthenium-iridium-terbium nanocatalysts with particle sizes within the above range can have higher specific surface areas and exhibit better oxygen evolution reaction (OER) catalytic activity.

[0030] According to a specific embodiment of the present invention, preferably, the preparation method of the above-mentioned ruthenium-iridium-terbium catalyst includes the following steps:

[0031] (1) Provide a mixed solution containing ruthenium ions, terbium ions and iridium ions;

[0032] (2) Add water-soluble organic matter as a metal ion complex to the mixed solution and dry it to obtain a gel precursor;

[0033] (3) The gel precursor is pulverized and calcined in an oxygen-containing atmosphere to obtain a ruthenium-iridium-terbium catalyst.

[0034] According to a specific embodiment of the present invention, preferably, in the above-described method for preparing the ruthenium-iridium-terbium catalyst, in the mixed solution of step (1), the molar ratio of ruthenium ions, terbium ions, and iridium ions is the same as that of the Tb2Ru x Ir 2-x The molar ratios of Ru, Tb, and Ir in O7 are the same. In step (1), deionized water can be used as the solvent for the mixed solution.

[0035] According to a specific embodiment of the present invention, preferably, in the above-described method for preparing the ruthenium-iridium-terbium catalyst, the concentration of ruthenium ions in the mixed solution is 0.001-0.1 mol / L, the concentration of terbium ions is 0.001-0.1 mol / L, and the concentration of iridium ions is 0.001-0.1 mol / L, based on the volume of the mixed solution. More preferably, the concentration of ruthenium ions in the mixed solution is 0.01-0.05 mol / L, the concentration of terbium ions is 0.01-0.05 mol / L, and the concentration of iridium ions is 0.005-0.02 mol / L.

[0036] According to a specific embodiment of the present invention, preferably, in the above-described method for preparing the ruthenium-iridium-terbium catalyst, the water-soluble organic compound is selected from one or more combinations of citric acid, glycine, malic acid, and ethylenediaminetetraacetic acid. In the preparation of the gel precursor of the present invention, only one water-soluble organic compound is needed as a metal ion complex, without the need to add alcohols.

[0037] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the ruthenium-iridium-terbium catalyst, the molar ratio of the water-soluble organic matter to the metal ions (i.e., the sum of ruthenium ions, terbium ions, and iridium ions) is 1:1 to 1:4.

[0038] According to a specific embodiment of the present invention, preferably, in the above preparation method, the drying temperature is 70℃-90℃, more preferably 80℃. In the process of preparing the gel precursor, the various raw materials only need to be mixed in water and dried at a low temperature, without the need for a long heating reaction process. Therefore, this process of the present invention is relatively simple and low in cost.

[0039] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing ruthenium-iridium-terbium catalyst, the calcination temperature is 700-1100℃ and the holding time is 1-12 hours.

[0040] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the ruthenium-iridium-terbium catalyst, the ruthenium ions are provided by one or a combination of two or more of ruthenium nitrate, ruthenium acetate, and ruthenium trichloride; the terbium ions are provided by one or a combination of two or more of terbium chloride, terbium nitrate, and terbium acetate; and the iridium ions are provided by iridium chloride and / or iridium tetrachloride.

[0041] The structure and properties of the catalyst layer have a significant impact on the activation polarization, concentration polarization, and ohmic polarization of electrochemical reactions. The catalyst in the catalyst layer is one of the key factors affecting activation polarization. In the ruthenium-iridium-terbium catalyst used in this invention, the terbium ion has a unique outermost 4f electron configuration (4f... 8 Half-filled or fully-filled orbitals are relatively stable and difficult to lose further electrons, while terbium ions, which can reach a half-filled state by losing just one electron, easily transition to an electron-deficient state (4f). 7 Due to the Tb-O-Ru double exchange interaction in pyrochlore, more electrons can be induced from ruthenium ions to terbium ions, thereby inducing more highly active pentavalent ruthenium sites. Furthermore, compared to existing technologies, the ruthenium-iridium-terbium catalyst used in this invention employs Ir... 4+ Replace some of the Ru in the pyrochlore-structured Tb2Ru2O7 4+ Compared to Tb₂Ru₂O₇, the ruthenium-iridium-terbium catalyst of this invention forms a [IrO₆]-[RuO₆] network structure. Electrons at ruthenium sites can be transferred to iridium sites via oxygen. This double exchange interaction constructs a spin-polarized charge transport channel, optimizes the spin distribution of d-orbital electrons in Ru and Ir, shortens the Ru-O bond length, effectively weakens the octahedral distortion caused by the Jameer-Taylor effect, and achieves the construction of a stable [IrO₆]-[RuO₆] framework. This alleviates the Jameer-Taylor distortion of the [RuO₆] units in pyrochlore, thereby making the active sites of the ruthenium-iridium-terbium catalyst more stable during the OER process, resulting in a more ideal octahedral stable framework structure, improving the intrinsic activity and stability of the catalyst, and thus promoting the oxygen evolution reaction. The ruthenium-iridium-terbium catalyst of this invention can uniformly and stably disperse Ir element in the pyrochlore structure from a microstructural perspective, which can improve the utilization rate of Ir element and thus reduce the amount of Ir element used in the membrane electrode.

[0042] By using the ruthenium-iridium-terbium catalyst provided by this invention to prepare an anode catalyst layer with an Ir elemental gradient, and then preparing a water electrolysis membrane electrode, the conduction of substances such as water, oxygen, protons, and electricity in the anode catalyst layer can be made smoother, thereby obtaining better catalytic activity and higher stability.

[0043] According to a specific embodiment of the present invention, preferably, in the anode catalyst layer for the above-mentioned water electrolysis membrane electrode, the ionomer is a perfluorosulfonic acid resin, such as at least one of DuPont Nafion resin, Solvay D79 series resin, Asahi Glass IC100 resin and Asahi Glass IC154 resin.

[0044] The present invention also provides a method for preparing the anode catalyst layer for the above-mentioned water electrolysis membrane electrode, which includes the following steps:

[0045] S1. Preparation of anode catalyst slurry: Mix water, ionomer, and liquid alcohol to obtain a dispersion; add the anode catalyst to the dispersion in portions to disperse it, and obtain the anode catalyst slurry corresponding to the first sublayer; repeat this step to obtain the anode catalyst slurry corresponding to the second to Nth sublayers;

[0046] S2. Preparation of the anode catalyst layer: The anode catalyst slurry corresponding to the first sublayer is coated onto the surface of the matrix membrane (e.g., proton exchange membrane) by spraying or coating to obtain the first sublayer. Then, the anode catalyst slurry corresponding to the second sublayer is coated onto the surface of the first sublayer. The coating process is repeated until the Nth sublayer is obtained, thereby forming the anode catalyst layer for the water electrolysis membrane electrode on the surface of the matrix membrane.

[0047] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the anode catalyst layer for the water electrolysis membrane electrode, step S1 includes:

[0048] S11. Place water in the inner cavity of the jacketed container and connect ice water to the outer cavity of the jacketed container for circulating cooling.

[0049] S12. Add ionomer and liquid alcohol to the inner cavity of the jacketed container in sequence to disperse them and obtain a dispersion.

[0050] S13. The anode catalyst is added to the dispersion in multiple portions for further dispersion to obtain the anode catalyst slurry corresponding to the first sublayer; this step is repeated to obtain the anode catalyst slurry corresponding to the second to the mth sublayer.

[0051] The Ir content of the anode catalyst slurry (slurry m) corresponding to the m-th sublayer is greater than or equal to the Ir content of the anode catalyst slurry (slurry m-1) corresponding to the (m-1)-th sublayer, while the ionomer content of slurry m is less than or equal to the ionomer content of slurry m-1.

[0052] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the anode catalyst layer for the water electrolysis membrane electrode, the dispersion is achieved by an ultrasonic crusher, a high-energy ball mill, a high-pressure homogenizer, or an ultrasonic cell pulverizer.

[0053] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the anode catalyst layer for the water electrolysis membrane electrode, in steps S12 and S13, the power of the ultrasonic crusher is 300-600W, the rotation speed of the high-energy ball mill is 1000-1500rpm, the dispersion pressure of the high-pressure homogenizer is 15000psi-17000psi, and the power of the ultrasonic cell disruptor is 600-1000W.

[0054] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the anode catalyst layer for the water electrolysis membrane electrode, in step 12, the dispersion time is 0.5-1 hour.

[0055] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the anode catalyst layer for the water electrolysis membrane electrode, the dispersion time in step 13 is 1-2 hours.

[0056] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the anode catalyst layer for the water electrolysis membrane electrode, the anode catalyst slurry, based on 100% by mass, contains: 0.5-30 wt% anode catalyst and 0.2-20% ionomer. In addition to the anode catalyst and ionomer, the anode catalyst slurry also contains water and liquid alcohol, and the water used can be deionized water.

[0057] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the anode catalyst layer for the water electrolysis membrane electrode, the ionomer is a perfluorosulfonic acid resin solution, and the concentration of the perfluorosulfonic acid resin solution is 5-20 wt%.

[0058] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the anode catalyst layer for the water electrolysis membrane electrode, the liquid alcohol is selected from one or more combinations of ethanol, propanol, butanol and isopropanol.

[0059] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the anode catalyst layer for water electrolysis membrane electrode, the volume ratio of water to liquid alcohol is 1:0.1-8. In the anode catalyst slurry of the present invention, when different water-to-alcohol ratios are used, the properties of the resulting solvent will also be different, including boiling point, viscosity, rheology, surface tension, dielectric constant, etc. These will affect the dispersion state of catalyst particles and ionic polymers, and thus affect the dispersibility, stability, and final performance of the catalyst slurry itself.

[0060] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the anode catalyst layer for the water electrolysis membrane electrode, the viscosity of the prepared anode catalyst slurry is 3 mPa·s-500 mPa·s. The specific viscosity of the slurry can be selected according to the process used in preparing the electrode. Generally, when preparing the membrane electrode: when the viscosity is within 10 mPa·s, ultrasonic spraying is suitable; when the viscosity is >10 mPa·s, coating is suitable.

[0061] Using the anode catalyst slurry and its preparation method provided by this invention, an anode slurry with uniform catalyst dispersion and suitable overall slurry viscosity can be obtained, avoiding problems such as catalyst sedimentation and agglomeration in the slurry, and avoiding the risk of subsequent membrane electrode catalyst layer cracking and peeling, which would affect catalytic performance. At the same time, by adjusting the slurry formulation (the content of catalyst, ionomer, solvent, etc. in the slurry) and preparation method during the slurry preparation process, the activity and stability of the ruthenium-iridium-terbium catalyst in the slurry can be maintained to the maximum extent, thereby improving the membrane electrode performance.

[0062] The present invention also provides a membrane electrode, wherein the membrane electrode comprises a proton exchange membrane, an anode catalyst layer and a cathode catalyst layer;

[0063] The anode catalyst layer is the anode catalyst layer for water electrolysis membrane electrode provided by the present invention;

[0064] Among them, starting from the proton exchange membrane, the sublayer numbers of the anode catalyst layer increase sequentially.

[0065] According to a specific embodiment of the present invention, in the above-mentioned membrane electrode, the sublayers are sequentially named as the 1st sublayer, the 2nd sublayer, ..., the (N-1)th sublayer, and the Nth sublayer, in order from the proton exchange membrane to the anode catalyst layer. The Ir content gradually increases and the ionomer content gradually decreases. The closer to the proton exchange membrane, the lower the Ir content and the higher the ionomer content in the sublayer.

[0066] According to a specific embodiment of the present invention, preferably, in the above-mentioned membrane electrode, the cathode catalyst of the cathode catalyst layer is a Pt / C catalyst.

[0067] According to a specific embodiment of the present invention, preferably, in the above-described membrane electrode, the Pt content of the cathode catalyst layer is 0.1-1.0 mg / cm², based on the area of ​​the cathode catalyst layer. 2 More preferably, it is 0.05-0.4 mg / cm³. 2 Further preferably, it is 0.10-0.20 mg / cm³. 2 .

[0068] According to a specific embodiment of the present invention, preferably, in the above-mentioned membrane electrode, the Pt element content in the Pt / C catalyst is 5-40% based on 100% by mass; more preferably 10-30%; and even more preferably 10-20%.

[0069] The present invention also provides a method for preparing the above-mentioned membrane electrode, which includes the following steps:

[0070] S1. Preparation of anode catalyst slurry: Mix water, ionomer, and liquid alcohol to obtain a dispersion; add the anode catalyst to the dispersion in portions to disperse it, and obtain the anode catalyst slurry corresponding to the first sublayer; repeat this step to obtain the anode catalyst slurry corresponding to the second to Nth sublayers;

[0071] S2. Preparation of anode catalyst layer: The anode catalyst slurry corresponding to the first sublayer is coated onto the surface of the matrix membrane (proton exchange membrane) by spraying or coating to obtain the first sublayer. Then, the anode catalyst slurry corresponding to the second sublayer is coated onto the surface of the first sublayer. The coating process is repeated until the Nth sublayer is obtained, thereby forming the anode catalyst layer for the water electrolysis membrane electrode on the surface of the matrix membrane.

[0072] S3. Preparation of cathode catalyst slurry: Water, ionomer, and liquid alcohol are mixed to obtain a dispersion; the cathode catalyst is added to the dispersion in portions to disperse it, thus obtaining the cathode catalyst slurry;

[0073] S4. Preparation of cathode catalyst layer: The cathode catalyst slurry is coated onto the other surface of the matrix membrane (proton exchange membrane) (i.e., the side surface not coated with the anode catalyst layer) by spraying or coating to obtain the cathode catalyst layer;

[0074] S5. The membrane coated with cathode catalytic layer and anode catalytic layer on both sides is hot-pressed to obtain the membrane electrode, namely the proton exchange membrane electrolysis water membrane electrode.

[0075] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the membrane electrode, step S3 includes:

[0076] S31. Place water in the inner cavity of the jacketed container and connect ice water to the outer cavity of the jacketed container for circulating cooling.

[0077] S32. Add ionomer and liquid alcohol to the inner cavity of the jacketed container in sequence to disperse them and obtain a dispersion.

[0078] S33. The cathode catalyst is added to the dispersion in multiple portions for further dispersion to obtain a cathode catalyst slurry.

[0079] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the membrane electrode, the dispersion in step S3 is achieved by an ultrasonic crusher, a high-energy ball mill, or an ultrasonic cell pulverizer.

[0080] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the membrane electrode, in steps S32 and S33, the power of the ultrasonic disruptor is 100-300W, the rotation speed of the high-energy ball mill is 500-800rpm, and the power of the ultrasonic cell disruptor is 200-400W.

[0081] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the membrane electrode, the dispersion time in step 32 is 0.5-1 hour.

[0082] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the membrane electrode, the dispersion time in step 33 is 0.5-1 hour.

[0083] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the membrane electrode, the cathode catalyst slurry, based on 100% by mass, contains: 0.5-5 wt% cathode catalyst and 0.5-5 wt% ionomer. In addition to the anode catalyst and ionomer, the cathode catalyst slurry also contains water and liquid alcohol, and the water used can be deionized water.

[0084] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the membrane electrode, the ionomer in the cathode catalyst slurry is a perfluorosulfonic acid resin solution, and the concentration of the perfluorosulfonic acid resin solution is 5-20 wt%.

[0085] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the membrane electrode, the liquid alcohol in the cathode catalyst slurry is selected from one or more combinations of ethanol, propanol, butanol and isopropanol.

[0086] According to a specific embodiment of the present invention, preferably, in the above-mentioned method for preparing the membrane electrode, the volume ratio of water to liquid alcohol in the cathode catalyst slurry is 1:0.5-10. In the cathode catalyst slurry of the present invention, different water-to-alcohol ratios result in different solvent properties, including boiling point, viscosity, rheology, surface tension, and dielectric constant. These properties affect the dispersion state of the catalyst particles and ionomers, thereby affecting the dispersibility, stability, and final catalytic layer performance of the catalyst slurry itself.

[0087] The membrane electrode provided by this invention can solve the problem of high precious metal content and overcome the adverse effects of traditional preparation methods on membrane electrode performance. By using catalyst materials such as doped ruthenium-iridium-terbium nano-oxidized catalysts, PEMWE membrane electrodes with low Ir content and Ir content gradient distribution can be prepared, thereby reducing the technical cost of PEMWE.

[0088] The membrane electrode of this invention exhibits an inverse gradient distribution of catalyst and ionomer content in the anode catalyst layer. The catalyst content increases with distance from the proton exchange membrane, while the ionomer content shows the opposite trend. Higher catalyst content in the sublayer corresponds to lower ionomer content; closer to the catalyst layer surface, the higher the demand for gas and liquid water transport, and the lower the demand for proton transport. Conversely, lower catalyst content corresponds to higher ionomer content; closer to the deeper layers of the catalyst layer, the lower the demand for gas and liquid water transport, and the higher the demand for proton transport. Therefore, the membrane electrode provided by this invention fully considers the transport characteristics of matter, protons, and electrons, thereby reducing the mass transfer resistance of the liquid phase, gas phase, and protons, and achieving the goal of improving the performance and durability of the membrane electrode. Attached Figure Description

[0089] Figure 1 shows the X-ray diffraction (XRD) patterns of the ruthenium-iridium-terbium catalysts prepared in Examples 1-3 and the Tb2Ru2O7 and Tb2Ir2O7 prepared in Comparative Examples 1-2.

[0090] Figure 2 shows scanning electron microscope (SEM) images of the ruthenium-iridium-terbium catalysts prepared in Preparation Examples 1-3 and the Tb2Ru2O7 and Tb2Ir2O7 prepared in Comparative Examples 1-2.

[0091] Figure 3 shows the particle size distribution statistics of the ruthenium-iridium-terbium catalysts prepared in Preparation Examples 1-3 and the Tb2Ru2O7 and Tb2Ir2O7 prepared in Comparative Examples 1-2.

[0092] Figure 4 shows the polarization curves of the ruthenium-iridium-terbium catalysts prepared in Examples 1-3 and the catalysts prepared in Comparative Examples 1-4 in 0.5 M sulfuric acid solution.

[0093] Figure 5 shows the ruthenium-iridium-terbium catalyst prepared in Example 1 of the present invention and the catalysts prepared in Comparative Examples 1-4 in 0.5M sulfuric acid solution and at 10 mA / cm 2 Chronopotential curves at current density. Detailed Implementation

[0094] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0095] The raw materials involved in the examples and comparative examples are as follows:

[0096] Deionized water: homemade, resistance 18.2MΩ;

[0097] Anode catalyst: Ruthenium-iridium-terbium catalyst: Tb2Ru 0.4 Ir 1.6 O7、Tb2Ru 1.0 Ir 1.0 O7、Tb2Ru 1.6 Ir 0.4 O7; Tb2Ru2O7 and Tb2Ir2O7 catalysts; TiO2-supported iridium oxide catalysts with Ir contents of 10%, 20%, and 40%, respectively.

[0098] Cathode catalysts: Pt / C catalysts with Pt contents of 10%, 20%, and 40%, respectively, wherein the carbon support is Cabot conductive carbon black VULCAN XC-72R.

[0099] Proton exchange membrane: DuPont N117 type proton exchange membrane.

[0100] Ionomers: Perfluorosulfonic acid resin solutions with contents of 5% and 20% respectively, Chemours.

[0101] Preparation Example 1

[0102] This preparation example provides a ruthenium-iridium-terbium catalyst with the molecular formula Tb₂Ru. 1.6 Ir 0.4 O7 has a pyrochlore structure and a particle size between 40nm and 180nm.

[0103] The preparation steps of this ruthenium-iridium-terbium catalyst are as follows:

[0104] (1) Dissolve 0.84g of citric acid in 20mL of deionized water, add 0.173g of terbium chloride, 0.083g of ruthenium nitrate and 0.015g of iridium chloride, and sonicate to dissolve evenly to obtain a mixed solution;

[0105] (2) The above mixed solution was placed in an oven at 80°C and dried and aged to obtain a fluffy dry gel. The dry gel was ball-milled to obtain gel powder.

[0106] (3) The above gel powder was heated in a muffle furnace at 1000℃ for 4 hours to obtain the powder product Tb2Ru. 1.6 Ir 0.4 O7.

[0107] Preparation Example 2

[0108] This preparation example provides a ruthenium-iridium-terbium catalyst with the molecular formula Tb₂Ru. 1.0 Ir 1.0 O7 has a pyrochlore structure and a particle size between 40nm and 160nm.

[0109] The preparation steps of this ruthenium-iridium-terbium catalyst are as follows:

[0110] (1) Dissolve 0.48g glycine in 20mL deionized water, add 0.055g iridium tetrachloride, 0.073g ruthenium acetate and 0.173g terbium chloride, and sonicate to dissolve evenly to obtain a mixed solution;

[0111] (2) The above mixed solution was placed in an oven at 80°C and dried and aged to obtain a fluffy dry gel. The dry gel was ball-milled to obtain gel powder.

[0112] (3) The above gel powder was heated in a muffle furnace at 1000℃ for 4 hours to obtain the powder product Tb2Ru. 1.0 Ir 1.0 O7.

[0113] Preparation Example 3

[0114] This preparation example provides a ruthenium-iridium-terbium catalyst with the molecular formula Tb₂Ru. 0.4 Ir 1.6 O7 has a pyrochlore structure and a particle size between 40nm and 140nm.

[0115] The preparation steps of this ruthenium-iridium-terbium catalyst are as follows:

[0116] (1) Dissolve 0.48g glycine in 20mL deionized water, add 0.088g iridium tetrachloride, 0.041g ruthenium trichloride and 0.173g terbium chloride, and sonicate to dissolve evenly to obtain a mixed solution;

[0117] (2) The above mixed solution was placed in an oven at 80°C and dried and aged to obtain a fluffy dry gel. The dry gel was ball-milled to obtain gel powder.

[0118] (3) The above gel powder was heated in a muffle furnace at 1000℃ for 4 hours to obtain the powder product Tb2Ru. 0.4 Ir 1.6 O7.

[0119] Preparation Example 4:

[0120] This preparation example provides 10 types of anode catalyst slurries and 3 types of cathode catalyst slurries, and their preparation methods are as follows:

[0121] Anode catalyst slurry 1:

[0122] S1: Place 5.8g of deionized water into the inner cavity of the jacketed container, and connect ice water to the outer cavity of the jacketed container for circulating cooling;

[0123] S2: Add 47.0g of perfluorosulfonic acid resin solution (mass concentration of 20%), 46.7g of isopropanol and n-butanol (mass ratio 1:1) sequentially into the inner cavity of the jacketed container, and disperse them using an ultrasonic crusher (power 600W) for 0.5 hours to obtain a dispersed solvent.

[0124] S3: Add 0.5g of TiO2-supported IrO2 catalyst (Ir content 10%) to the dispersed solvent of S2 in three portions, and continue to disperse using an ultrasonic crusher for 1 hour to obtain anode catalyst slurry 1.

[0125] Anode catalyst slurry 2:

[0126] S1: Place 8.7g of deionized water into the inner cavity of the jacketed container, and connect ice water to the outer cavity of the jacketed container for circulating cooling;

[0127] S2: Add 37.5g of perfluorosulfonic acid resin solution (mass concentration of 20%), 43.8g of isopropanol and ethanol (mass ratio 1:1) in sequence to the inner cavity of the jacketed container, and disperse it in a high-energy ball mill (speed 1500 rpm) for 1.0 hour to obtain a dispersed solvent.

[0128] S3: 10g of TiO2-supported IrO2 catalyst (Ir content 20%) was added to the dispersed solvent of S2 in three portions, and the dispersion was continued for 2 hours using a high-energy ball mill to obtain anode catalyst slurry 2.

[0129] Anode catalyst slurry 3:

[0130] S1: Place 45.8g of deionized water into the inner cavity of the jacketed container, and connect ice water to the outer cavity of the jacketed container for circulating cooling;

[0131] S2: Add 25g of perfluorosulfonic acid resin solution (mass concentration of 20%), 9.2g of isopropanol and n-propanol (mass ratio 1:1) sequentially into the inner cavity of the jacketed container, and disperse it in a high-energy ball mill (speed 1500 rpm) for 1.0 hour to obtain a dispersed solvent.

[0132] S3: 20g of TiO2-supported IrO2 catalyst (Ir content 40%) was added to the dispersed solvent of S2 in three portions, and the dispersion was continued for 2 hours using a high-energy ball mill to obtain anode catalyst slurry 3.

[0133] Anode catalyst slurry 4:

[0134] S1: Place 19.8g of deionized water into the inner cavity of the jacketed container, and connect ice water to the outer cavity of the jacketed container for circulating cooling;

[0135] S2: Add 20g of perfluorosulfonic acid resin solution (mass concentration of 20%), 59.2g of ethanol and n-propanol (mass ratio of 1:1) sequentially into the inner cavity of the jacketed container, and disperse it for 0.5 hours using a high-pressure homogenizer (dispersion pressure of 15000psi) to obtain the dispersed solvent.

[0136] S3: 1.0g of Tb2Ru prepared in Example 1 1.6 Ir 0.4 The O7 catalyst was added to the dispersed solvent of S2 in three portions, and the mixture was further dispersed using a high-pressure homogenizer for 1.5 hours to obtain the anode catalyst slurry 4.

[0137] Anode catalyst slurry 5:

[0138] S1: Place 2.3g of deionized water into the inner cavity of the jacketed container, and connect ice water to the outer cavity of the jacketed container for circulating cooling;

[0139] S2: Add 66.5g of perfluorosulfonic acid resin solution (mass concentration of 20%), 11.2g of n-butanol and ethanol (mass ratio 1:1) in sequence to the inner cavity of the jacketed container, and disperse it in a high-energy ball mill (speed 1000 rpm) for 1.0 hour to obtain a dispersed solvent.

[0140] S3: Take 20g of Tb2Ru prepared in Example 3. 0.4 Ir 1.6 The O7 catalyst was added to the dispersed solvent of S2 in two portions, and the mixture was further dispersed using a high-energy ball mill for 2 hours to obtain the anode catalyst slurry 5.

[0141] Anode catalyst slurry 6:

[0142] S1: Place 6.9g of deionized water into the inner cavity of the jacketed container, and connect ice water to the outer cavity of the jacketed container for circulating cooling;

[0143] S2: Add 56.5g of perfluorosulfonic acid resin solution (mass concentration of 20%), 34.6g of n-butanol and ethanol (mass ratio 1:1) in sequence to the inner cavity of the jacketed container, and disperse it for 1.0 hour using an ultrasonic crusher (power 400W) to obtain a dispersed solvent.

[0144] S3: Take 2g of Tb2Ru prepared in Example 2 1.0 Ir 1.0 The O7 catalyst was added to the dispersed solvent of S2 in two portions, and then dispersed for another 2 hours using an ultrasonic crusher to obtain the anode catalyst slurry 6.

[0145] Anode catalyst slurry 7:

[0146] S1: Place 35.2g of deionized water into the inner cavity of the jacketed container, and connect ice water to the outer cavity of the jacketed container for circulating cooling;

[0147] S2: Add 32.2g of perfluorosulfonic acid resin solution (mass concentration of 20%), 17.6g of isopropanol, n-propanol and ethanol (mass ratio 1:1:1) in sequence to the inner cavity of the jacketed container, and disperse it in a high-energy ball mill (speed 1000 rpm) for 1.0 hour to obtain a dispersed solvent.

[0148] S3: 15g of Tb2Ru prepared in Example 3 was used. 0.4 Ir 1.6 The O7 catalyst was added to the dispersed solvent of S2 in two portions, and the mixture was further dispersed using a high-energy ball mill for 2 hours to obtain the anode catalyst slurry 7.

[0149] Anode catalyst slurry 8:

[0150] S1: Take 4.4g of deionized water and place it in the inner cavity of the jacketed container. Connect ice water to the outer cavity of the jacketed container for circulating cooling.

[0151] S2: Add 67.5g of perfluorosulfonic acid resin solution (mass concentration of 20%), 26.1g of ethanol and n-propanol (mass ratio 1:1) sequentially into the inner cavity of the jacketed container, and disperse it for 0.5 hours using a high-pressure homogenizer (dispersion pressure of 15000psi) to obtain the dispersed solvent.

[0152] S3: 2.0g of Tb2Ru prepared in Example 1 1.6 Ir 0.4 The O7 catalyst was added to the dispersed solvent of S2 in three portions, and the mixture was further dispersed using a high-pressure homogenizer for 1.5 hours to obtain the anode catalyst slurry 8.

[0153] Anode catalyst slurry 9:

[0154] S1: Place 10.4g of deionized water into the inner cavity of the jacketed container, and connect ice water to the outer cavity of the jacketed container for circulating cooling;

[0155] S2: Add 40g of perfluorosulfonic acid resin solution (mass concentration of 20%), 41.6g of ethanol and isopropanol (mass ratio of 1:1) sequentially into the inner cavity of the jacketed container, and disperse it for 1 hour using a high-pressure homogenizer (dispersion pressure of 15000psi) to obtain the dispersed solvent.

[0156] S3: 8.0g of Tb2Ru prepared in Example 2 1.0 Ir 1.0 The O7 catalyst was added to the dispersed solvent of S2 in three portions, and the mixture was further dispersed using a high-pressure homogenizer for 2 hours to obtain the anode catalyst slurry 9.

[0157] Anode catalyst slurry 10:

[0158] S1: Place 46g of deionized water into the inner cavity of the jacketed container, and connect ice water to the outer cavity of the jacketed container for circulating cooling.

[0159] S2: Add 5g of perfluorosulfonic acid resin solution (mass concentration of 20%), 46g of isopropanol and n-propanol (mass ratio 1:1) sequentially into the inner cavity of the jacketed container, and disperse them using an ultrasonic crusher (power 400W) for 0.5 hours to obtain a dispersed solvent.

[0160] S3: 3.0g of Tb2Ru prepared in Example 3 0.4 Ir 1.6 The O7 catalyst was added to the dispersed solvent of S2 in three portions, and the dispersion was further carried out using an ultrasonic crusher for 1.5 hours to obtain 10 anode catalyst slurry.

[0161] Cathode catalyst slurry 1:

[0162] S1: Place 46g of deionized water into the inner cavity of the jacketed container, and connect ice water to the outer cavity of the jacketed container for circulating cooling.

[0163] S2: Add 5g of perfluorosulfonic acid resin solution (mass concentration of 20%), 46g of isopropanol and n-propanol (mass ratio 1:1) in sequence to the inner cavity of the jacketed container, and disperse it with an ultrasonic crusher (power 300W) for 0.5 hours to obtain a dispersed solvent.

[0164] S3: Add 3.0g of Pt / C catalyst (Pt content 10%) to the dispersed solvent of S2 in three portions, and continue to disperse using an ultrasonic crusher for 0.5 hours to obtain cathode catalyst slurry 1.

[0165] Cathode catalyst slurry 2:

[0166] S1: Place 46g of deionized water into the inner cavity of the jacketed container, and connect ice water to the outer cavity of the jacketed container for circulating cooling.

[0167] S2: Add 5g of perfluorosulfonic acid resin solution (mass concentration of 20%), 46g of isopropanol and n-propanol (mass ratio 1:1) in sequence to the inner cavity of the jacketed container, and disperse it with an ultrasonic crusher (power 200W) for 0.5 hours to obtain a dispersed solvent.

[0168] S3: Add 3.0g of Pt / C catalyst (Pt content 20%) to the dispersed solvent of S2 in three portions, and continue to disperse using an ultrasonic crusher for 0.5 hours to obtain cathode catalyst slurry 2.

[0169] Cathode catalyst slurry 3:

[0170] S1: Place 46g of deionized water into the inner cavity of the jacketed container, and connect ice water to the outer cavity of the jacketed container for circulating cooling.

[0171] S2: Add 5g of perfluorosulfonic acid resin solution (mass concentration of 20%), 46g of isopropanol and n-propanol (mass ratio 1:1) sequentially into the inner cavity of the jacketed container, and disperse them using an ultrasonic crusher (power 100W) for 0.5 hours to obtain a dispersed solvent.

[0172] S3: Add 3.0g of Pt / C catalyst (Pt content 40%) to the dispersed solvent of S2 in three portions, and continue to disperse using an ultrasonic crusher for 0.5 hours to obtain cathode catalyst slurry 3.

[0173] Example 1

[0174] This embodiment provides a membrane electrode A1, the preparation method of which is as follows:

[0175] Anode catalyst slurry 1, anode catalyst slurry 2, and anode catalyst slurry 3 were sequentially coated onto one side of the proton exchange membrane using a coating machine (the coating process was carried out by slit coating, with a heating temperature of 70°C and a travel speed of 30 mm / s) to obtain an anode catalyst layer containing three sublayers. After each sublayer was coated, the metal content was determined using a handheld X-ray fluorescence spectrometer. The Ir content of each sublayer was the current measured content minus the measured content of the previous layer.

[0176] The cathode catalyst slurry 1 was sprayed onto the other side of the proton exchange membrane using an ultrasonic spraying machine (the spraying process was carried out by ultrasonic spraying, wherein the nozzle height of the spray gun was 30 mm, the ultrasonic transducer frequency was 35 kHz, the slurry flow rate was 1.5 mL / min, the travel speed was 7200 mm / min, and the heating plate temperature was 90 ℃). The Pt element content was determined using a handheld X-ray fluorescence spectrometer.

[0177] The proton exchange membrane coated with the anode and cathode catalyst layers was placed in a hot press for hot pressing (temperature 140℃, pressure 3MPa, hot pressing time 2min) to obtain membrane electrode A1.

[0178] Example 2

[0179] This embodiment provides a membrane electrode A2, the preparation method of which is as follows:

[0180] Using an ultrasonic sprayer and a coating machine, anode catalyst slurry 4 and anode catalyst slurry 5 were sequentially coated onto one side of the proton exchange membrane (the coating process was carried out by slit coating, with a heating temperature of 70°C and a travel speed of 30 mm / s) to obtain an anode catalyst layer containing two sublayers. After each sublayer was coated, the metal content was determined using a handheld X-ray fluorescence spectrometer. The Ir content of each sublayer was the current measured content minus the measured content of the previous layer.

[0181] The cathode catalyst slurry 2 was sprayed onto the other side of the proton exchange membrane using an ultrasonic spraying machine (the spraying process was carried out by ultrasonic spraying, wherein the nozzle height of the spray gun was 30 mm, the ultrasonic transducer frequency was 35 kHz, the slurry flow rate was 1.5 mL / min, the travel speed was 7200 mm / min, and the heating plate temperature was 90 ℃). The Pt element content was determined using a handheld X-ray fluorescence spectrometer.

[0182] The proton exchange membrane coated with the anode and cathode catalyst layers was placed in a hot press for hot pressing (temperature 140℃, pressure 3MPa, hot pressing time 2min) to obtain membrane electrode A2.

[0183] Example 3

[0184] This embodiment provides a membrane electrode A3, the preparation method of which is as follows:

[0185] Anode catalyst slurry 6 and anode catalyst slurry 7 were sequentially coated onto one side of the proton exchange membrane using a coating machine (the coating process was carried out by slit coating, with a heating temperature of 70°C and a travel speed of 30 mm / s) to obtain an anode catalyst layer containing two sublayers. After each sublayer was coated, the metal content was determined using a handheld X-ray fluorescence spectrometer. The Ir content of each sublayer was the current measured content minus the measured content of the previous layer.

[0186] The cathode catalyst slurry 3 was sprayed onto the other side of the proton exchange membrane using an ultrasonic spraying machine (the spraying process was carried out by ultrasonic spraying, wherein the nozzle height of the spray gun was 30 mm, the ultrasonic transducer frequency was 35 kHz, the slurry flow rate was 1.5 mL / min, the travel speed was 7200 mm / min, and the heating plate temperature was 90 ℃). The Pt element content was determined using a handheld X-ray fluorescence spectrometer.

[0187] The proton exchange membrane coated with the anode and cathode catalyst layers was placed in a hot press for hot pressing (temperature 140℃, pressure 3MPa, hot pressing time 2min) to obtain membrane electrode A3.

[0188] Example 4

[0189] This embodiment provides a membrane electrode A4, the preparation method of which is as follows:

[0190] Anode catalyst slurry 8 and anode catalyst slurry 9 were sequentially coated onto one side of the proton exchange membrane using a coating machine (the coating process was carried out by slit coating, with a heating temperature of 70℃ and a travel speed of 30mm / s). Then, anode catalyst slurry 10 was coated onto the sublayer prepared by anode catalyst slurry 9 using an ultrasonic spraying machine (the spray gun nozzle height was 30mm, the ultrasonic transducer frequency was 35kHz, the slurry flow rate was 1.5mL / min, the travel speed was 7200mm / min, and the heating plate temperature was 90℃). This resulted in an anode catalyst layer containing three sublayers. After each sublayer coating was completed, the metal content was determined using a handheld X-ray fluorescence spectrometer. The Ir content of each sublayer was the current measured content minus the measured content of the previous layer.

[0191] The cathode catalyst slurry 1 was sprayed onto the other side of the proton exchange membrane using an ultrasonic spraying machine (the spraying process was carried out by ultrasonic spraying, wherein the nozzle height of the spray gun was 30 mm, the ultrasonic transducer frequency was 35 kHz, the slurry flow rate was 1.5 mL / min, the travel speed was 7200 mm / min, and the heating plate temperature was 90 ℃). The Pt element content was determined using a handheld X-ray fluorescence spectrometer.

[0192] The proton exchange membrane coated with the anode and cathode catalyst layers was placed in a hot press for hot pressing (temperature 140℃, pressure 3MPa, hot pressing time 2min) to obtain membrane electrode A4.

[0193] Preparation of Comparative Example 1

[0194] This comparative example provides a Tb2Ru2O7 catalyst with a pyrochlore structure and a particle size between 40 nm and 180 nm.

[0195] The steps for preparing the Tb₂Ru₂O₇ catalyst are as follows:

[0196] (1) Dissolve 0.84g of citric acid in 20mL of deionized water, add 0.103g of ruthenium trichloride and 0.173g of terbium chloride, and sonicate to dissolve evenly to obtain a mixed solution;

[0197] (2) The above mixed solution was placed in an oven at 80°C and dried and aged to obtain a fluffy dry gel. The dry gel was ball-milled to obtain gel powder.

[0198] (3) The above gel powder was placed in a muffle furnace at 1100℃ and heated for 2 hours to obtain the powder product Tb2Ru2O7.

[0199] Preparation of Comparative Example 2

[0200] This comparative example provides a Tb2Ir2O7 catalyst with a pyrochlore structure and a particle size between 40 nm and 140 nm.

[0201] The preparation steps of this Tb₂Ir₂O₇ catalyst are as follows:

[0202] (1) Dissolve 0.84g of citric acid in 20mL of deionized water, add 0.11g of iridium tetrachloride and 0.173g of terbium chloride, and sonicate to dissolve evenly to obtain a mixed solution;

[0203] (2) The above mixed solution was placed in an oven at 80°C and dried and aged to obtain a fluffy dry gel. The dry gel was ball-milled to obtain gel powder.

[0204] (3) The above gel powder was placed in a muffle furnace at 1100℃ and heated for 6 hours to obtain the powder product Tb2Ir2O7.

[0205] Preparation of Comparative Example 3

[0206] This comparative example provides a commercially available anhydrous iridium oxide catalyst with the molecular formula IrO2, purchased from Alfaisa (China) Chemical Co., Ltd., CAS number 12030-49-8, with a purity of 99.99%.

[0207] Preparation of Comparative Example 4

[0208] This comparative example provides a commercially available anhydrous ruthenium oxide catalyst with the molecular formula RuO2, purchased from Alfaesa (China) Chemical Co., Ltd., CAS number 12036-10-1, with a purity of 99.95%.

[0209] Comparative Example 1

[0210] This comparative example provides a membrane electrode, the preparation method of which is as follows:

[0211] Add 19.18g of water to a glass bottle, place the bottle on a magnetic stirrer, add a stirring rod, and adjust the speed to 500rpm. Weigh 14.21g of IrO2@TiO2 (TiO2-supported IrO2, anode catalyst) with a mass percentage of 50wt% and a TiO2 particle size of 100nm, and add it to the glass bottle. Then add 20.30g of perfluorosulfonic acid solution (Cholmours D2020, ionomerized electronic conductor) with a solid content of 20.0%, and finally add 19.18g of n-propanol. After stirring for 30 minutes, the anode precursor slurry is obtained.

[0212] Following the same method, 50 wt% IrO2@TiO2 was replaced with 60 wt% Pt / C catalyst, and the cathode precursor slurry was obtained by following the same steps.

[0213] The anode precursor slurry was transferred to a ball milling jar containing milling beads, and then the ball milling jar was placed in a ball mill. The ball milling speed was set to 600 rpm and the ball milling time was 2 hours. After ball milling and dispersion, the mixture was mixed and degassed using a degassing machine to obtain the anode catalyst slurry.

[0214] The anode catalyst slurry was coated onto the PTFE membrane (transfer membrane) using a slit coater and dried to obtain the anode catalyst layer. The cathode catalyst slurry was coated onto the PTFE membrane (transfer membrane) using a slit coater and dried to obtain the anode catalyst layer. The obtained anode and cathode catalyst layers were then transferred to both sides of the N117 proton exchange membrane by hot pressing (temperature 140℃, pressure 2MPa, time 3 minutes) to obtain the membrane electrode of Comparative Example 1.

[0215] Comparative Example 2

[0216] This comparative example provides a membrane electrode, the preparation method of which is as follows:

[0217] Anode slurry preparation: Three types of catalyst slurries were prepared using 50 wt% IrO2@TiO2 powder, ionomer-based electronic conductor (Aquivion D79, content 20%), and dispersion solvent (deionized water: n-propanol = 6:4).

[0218] Slurry A: Ionomer content 5%, catalyst content 22.5%; raw material usage: IrO2@TiO2 powder 22.5g, ionomer quantum conductor 12.5g, deionized water 39g, n-propanol 26g;

[0219] Slurry B: Ionomer content 10%, catalyst content 17.5%; raw material usage: IrO2@TiO2 powder 17.5g, ionomer quantum conductor 50g, deionized water 19.5g, n-propanol 13g;

[0220] Slurry C: Ionomer content 15%, catalyst content 12.5%; raw material usage: IrO2@TiO2 powder 12.5g, ionomer quantum conductor 75g, deionized water 7.5g, n-propanol 5g.

[0221] In the three slurries, the percentages of ionomers in the total mass of the slurry were 5%, 10%, and 15%, respectively, and the percentages of catalysts in the total mass of the slurry were 22.5%, 17.5%, and 12.5%, respectively. Each slurry was ball-milled (300 rpm) for 4 hours to obtain the desired anode slurry.

[0222] Cathode slurry preparation: 20g of 60% wt Pt / C (Johnson Matthey Company), 62.5g of Nafion solution (DuPont, D2020, ionomer content 20%), 12.5g of isopropanol (China National Pharmaceutical Group, purity ≥99.9%) and 5g of deionized water (18MΩ / cm) were mixed, and then the slurry was dispersed by ball milling at 300rpm for 4 hours to obtain the cathode slurry, wherein the I / C ratio was 0.625.

[0223] Membrane electrode preparation: Anode and cathode catalyst slurries were coated onto PTFE (50 μm thick) using a coating machine. The three anode slurries were coated in increasing order of 5%, 10%, and 15%, while the cathode was directly coated. After coating, the PTFE membrane was dried under infrared light at 120°C for 4 minutes. Then, the cathode and anode catalyst layers coated on the PTFE membrane were hot-pressed onto a Nafion 117 membrane using a thermal transfer process (temperature 140°C, pressure 2 MPa, time 3 minutes) to obtain the membrane electrode.

[0224] Comparative Example 3

[0225] This comparative example provides a membrane electrode, which differs from Comparative Example 1 in that the IrO2@TiO2 in Comparative Example 1 is replaced with the Tb2Ru2O7 catalyst used to prepare Comparative Example 1, while the other steps remain unchanged.

[0226] Comparative Example 4

[0227] This comparative example provides a membrane electrode. The difference from Comparative Example 1 is that the IrO2@TiO2 in Comparative Example 1 is replaced with the Tb2Ir2O7 catalyst used to prepare Comparative Example 2, while the other steps remain the same.

[0228] Comparative Example 5

[0229] This comparative example provides a membrane electrode, which differs from Comparative Example 1 in that the IrO2@TiO2 in Comparative Example 1 is replaced with the commercially available IrO2 catalyst used to prepare Comparative Example 3, while the other steps remain unchanged.

[0230] Comparative Example 6

[0231] This comparative example provides a membrane electrode that differs from Comparative Example 1 in that the IrO2@TiO2 in Comparative Example 1 is replaced with the commercial RuO2 catalyst used to prepare Comparative Example 4, while the remaining steps remain unchanged.

[0232] Test Example 1

[0233] To better illustrate the properties of the obtained materials, corresponding performance tests were performed on the materials prepared in Examples 1-3 and Comparative Examples 1-4:

[0234] (1) XRD characterization

[0235] X-ray powder diffraction was performed on the materials prepared in Preparation Examples 1-3 and Comparative Examples 1-2. The X-ray diffraction (XRD) patterns of the ruthenium-iridium-terbium catalysts prepared in Preparation Examples 1-3 and the Tb₂Ru₂O₇ and Tb₂Ir₂O₇ catalysts prepared in Comparative Examples 1-2 are shown in Figure 1. As can be seen from Figure 1, the Ir-substituted Ru ruthenium-iridium-terbium catalysts of Preparation Examples 1-3 and the undoped Tb₂Ru₂O₇ and Tb₂Ir₂O₇ catalysts of Comparative Examples 1-2 have similar characteristic peaks, but the diffraction peaks are slightly shifted to lower angles, indicating that iridium doping causes a slight expansion of the lattice.

[0236] (2) SEM characterization

[0237] The materials prepared in Preparation Examples 1-3 and Comparative Examples 1-2 were subjected to scanning electron microscopy (SEM) analysis. Figure 2 shows the SEM images of the ruthenium-iridium-terbium catalysts prepared in Preparation Examples 1-3 and the Tb₂Ru₂O₇ and Tb₂Ir₂O₇ catalysts prepared in Comparative Examples 1-2. As can be seen from Figure 2, the Ir-substituted Ru ruthenium-iridium-terbium catalysts of Preparation Examples 1-3 and the undoped Tb₂Ru₂O₇ and Tb₂Ir₂O₇ catalysts of Comparative Examples 1-2 have similar particle sizes, ranging from 40 nm to 180 nm.

[0238] Figure 3 shows the particle size distribution of the ruthenium-iridium-terbium catalysts prepared in Examples 1-3 and the catalysts prepared in Comparative Examples 1-2. As can be seen from Figure 3, the particle size of the catalysts in Examples 1-3 tends to decrease after Ir doping substitution, indicating that doping substitution plays a role in refining the grain size.

[0239] (3) Electrochemical testing

[0240] Electrochemical tests were performed on the catalyst materials obtained in Preparation Examples 1-3 and Comparative Examples 1-4. Three-electrode tests were conducted in acidic solutions, specifically according to the following steps:

[0241] Take 4 mg of each of the materials obtained from Preparation Examples 1-3 and Preparation Comparative Examples 1 and 3, mix them with 1 mg of acetylene black, dissolve them in 0.5 mL of ethanol, and sonicate them for 30 minutes respectively.

[0242] Add 20 μL of 5 wt% Nafion solution to each electrode and continue dispersing for 30 minutes. Take 5 μL and coat it onto a glassy carbon electrode with a diameter of 4 mm. Let it air dry to obtain the electrode.

[0243] Using the aforementioned electrode as the working electrode, the standard hydrogen electrode as the reference electrode, and the shape-stable anode as the counter electrode (shape-stable anode refers to the coated titanium anode, commonly known as the size-stable anode, abbreviated as DSA), a three-electrode electrochemical system was formed, and its electrochemical performance was tested in 0.5 M H2SO4 solution. The voltage scan range of the polarization curve was 1.1–1.6 V, and the scan rate was 10 mV / s. The polarization curves of the ruthenium-iridium-terbium catalysts prepared in Examples 1–3 and the catalysts prepared in Comparative Examples 1–4 in 0.5 M sulfuric acid solution are shown in Figure 4, and the overpotential results are shown in Table 1.

[0244] The working electrode is at 10 mA / cm 2 The current density was continuously operated in a three-electrode electrolytic cell, and the voltage change curve over time was recorded. The ruthenium-iridium-terbium catalyst prepared in Example 1 and the catalysts prepared in Comparative Examples 1 and 4 were tested in 0.5 M sulfuric acid solution at 10 mA / cm². 2 Figure 5 shows the chronopotential curves under current density:

[0245] Table 1

[0246] As can be seen from the overpotential data shown in Table 1, the catalyst used in this invention has high oxygen evolution activity. The preparation examples 1-3 and the preparation comparative example 1 all have better oxygen evolution reaction catalytic activity than the commercial catalysts in the preparation comparative examples 3-4, which proves that the ruthenium-iridium-terbium catalyst and its preparation method used in this invention are advanced.

[0247] As can be seen from Figure 4 and Table 1, at a potential of 1.5V relative to the standard hydrogen electrode potential, the current density of Preparation Example 1 is higher than that of Preparation Comparative Examples 1-2, and much higher than that of Preparation Comparative Examples 3-4.

[0248] As can be seen from Figure 5 and Table 1, during the constant current electrolysis process of more than 30 hours, the voltage of the electrode of the catalyst of Preparation Example 1 did not change significantly, while the electrode made of Tb2Ru2O7 of Comparative Example 1 showed a significant performance degradation after 10 hours of electrolysis. This indicates that the ruthenium-iridium-terbium catalyst used in this invention can significantly improve the intrinsic stability in the acidic oxygen evolution reaction.

[0249] Therefore, the oxygen evolution reaction catalyst used in this invention has the characteristics of high catalytic activity and good stability, and its preparation method is simple and easy to repeat.

[0250] Test Example 2

[0251] This test example demonstrates membrane electrode characterization and catalytic performance testing.

[0252] Table 2 lists the Ir content of the anode and cathode catalyst layers in Examples 1-4 and Comparative Examples 1-6.

[0253] Table 2

[0254] Table 3 lists the ionomer content of the anode catalyst layers in Examples 1-4.

[0255] Table 3

[0256] The membrane electrodes prepared in the examples and comparative examples were installed in a PEM water electrolysis membrane electrode test fixture for testing. Test conditions: the anode diffusion layer was platinum-plated titanium felt, the cathode diffusion layer was carbon cloth, and the membrane electrode working area was 25 cm². 2 The water temperature is 80℃, and the current density is set at 2A / cm². 2 The membrane electrode was continuously operated for 1000 hours, and its initial and final operating voltages were tested. The specific test results for membrane electrode stability are shown in Table 4. The voltage change rate was calculated using the following formula:

[0257] Voltage change rate = (final operating voltage - initial operating voltage) / initial operating voltage × 100%.

[0258] Table 4

[0259] As shown in Table 3, the initial and final operating voltages of Examples 1-4 are very similar, indicating stable catalytic performance. The initial operating voltages of Comparative Examples 1-6 are not significantly different from those of Examples 1-4, but the final operating voltages are higher, indicating poorer performance stability of the membrane electrode.

[0260] The above embodiments illustrate and describe the main features and advantages of the present invention in detail. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. An anode catalyst layer for a water electrolysis membrane electrode, wherein, The anode catalyst layer of the water electrolysis membrane electrode is composed of N sublayers, where N≥2; Each sublayer contains an anolyte catalyst and an ionomer; the anolyte catalyst is selected from one or a combination of two of supported iridium oxide catalysts and ruthenium-iridium-terbium catalysts, wherein the ruthenium-iridium-terbium catalyst has a pyrochlore structure and the molecular formula Tb₂Ru. x Ir 2-x O7, where 0 <x<2; The Ir content gradually increases from the first sublayer to the Nth sublayer, while the ionomer content gradually decreases.

2. The anode catalyst layer for a water electrolysis membrane electrode according to claim 1, wherein, The N≥3.

3. The anode catalyst layer for a water electrolysis membrane electrode according to claim 1, wherein, The Ir content of the m-th sublayer is 1 to 10 times that of the (m-1)-th sublayer, where m is the sublayer number.

4. The anode catalyst layer for a water electrolysis membrane electrode according to claim 1 or 3, wherein, The ionomer content of the m-th sublayer is 0.2 to 1 times that of the (m-1)-th sublayer, where m is the sublayer number.

5. The anode catalyst layer for a water electrolysis membrane electrode according to claim 1, wherein, Based on the area of ​​the anode catalyst layer for the water electrolysis membrane electrode, the catalyst content of the anode catalyst layer for the water electrolysis membrane electrode is 1.0-4.0 mg / cm². 2 .

6. The anode catalyst layer for a water electrolysis membrane electrode according to claim 1, wherein, Based on the area of ​​the anode catalyst layer for the water electrolysis membrane electrode, the Ir content of the anode catalyst layer for the water electrolysis membrane electrode is 0.1-1.9 mg / cm². 2 .

7. The anode catalyst layer for a water electrolysis membrane electrode according to claim 1, wherein, In the anode catalyst layer of the water electrolysis membrane electrode, the mass ratio of the ionomer to the anode catalyst is 1:1-5.

8. The anode catalyst layer for a water electrolysis membrane electrode according to claim 1, wherein, Based on the area of ​​the anode catalyst layer for the water electrolysis membrane electrode, the catalyst content of the anode catalyst layer for the water electrolysis membrane electrode is 2.0-3.0 mg / cm². 2 .

9. The anode catalyst layer for a water electrolysis membrane electrode according to claim 1, wherein, Based on the area of ​​the anode catalyst layer for the water electrolysis membrane electrode, the Ir content of the anode catalyst layer for the water electrolysis membrane electrode is 0.2-1.0 mg / cm². 2 .

10. The anode catalyst layer for a water electrolysis membrane electrode according to claim 1, wherein, In the anode catalyst layer of the water electrolysis membrane electrode, the mass ratio of the ionomer to the anode catalyst is 1:1-4.

11. The anode catalyst layer for a water electrolysis membrane electrode according to claim 1, wherein, The support for the supported iridium oxide catalyst is selected from one or more combinations of TiO2, Nb2O5, and Ta2O5.

12. The anode catalyst layer for a water electrolysis membrane electrode according to claim 1, wherein, The anode catalyst is selected from one or more of the ruthenium-iridium-terbium catalysts.

13. The anode catalyst layer for a water electrolysis membrane electrode according to claim 1 or 12, wherein, In the molecular formula of the ruthenium-iridium-terbium catalyst, 0.05 ≤ x ≤ 1.

95.

14. The anode catalyst layer for a water electrolysis membrane electrode according to claim 13, wherein, The ruthenium iridium catalyst is Tb2Ru 1.95 And 0.05 O7、Tb2Ru 1.90 And 0.10 O7、Tb2Ru 1.85 And 0.15 O7、Tb2Ru 1.80 And 0.20 O7、Tb2Ru 1.75 And 0.25 O7、Tb2Ru 1.70 And 0.30 O7、Tb2Ru 1.65 And 0.35 O7、Tb2Ru 1.60 And 0.40 O7、Tb2Ru 1.55 And 0.45 O7、Tb2Ru 1.50 And 0.50 O7、Tb2Ru 1.45 And 0.55 O7、Tb2Ru 1.40 And 0.60 O7、Tb2Ru 1.35 And 0.65 O7、Tb2Ru 1.30 And 0.70 O7、Tb2Ru 1.25 And 0.75 O7、Tb2Ru 1.20 And 0.80 O7、Tb2Ru 1.15 And 0.85 O7、Tb2Ru 1.10 And 0.90 O7、Tb2Ru 1.05 And 0.95 O7、Tb2Ru 1.00 And 1.00 O7、Tb2Ru 0.95 And 1.05 O7、Tb2Ru 0.90 And 1.10 O7、Tb2Ru 0.85 And 1.15 O7、Tb2Ru 0.80 And 1.20 O7、Tb2Ru 0.75 And 1.25 O7、Tb2Ru 0.70 And 1.30 O7、Tb2Ru 0.65 And 1.35 O7、Tb2Ru 0.60 Ir 1.40 O7, Tb2Ru 0.55 Ir 1.45 O7, Tb2Ru 0.50 Ir 1.50 O7, Tb2Ru 0.45 Ir 1.55 O7, Tb2Ru 0.40 Ir 1.60 O7, Tb2Ru 0.35 Ir 1.65 O7, Tb2Ru 0.30 Ir 1.70 O7, Tb2Ru 0.25 Ir 1.75 O7, Tb2Ru 0.20 Ir 1.80 O7, Tb2Ru 0.15 Ir 1.85 O7, Tb2Ru 0.10 Ir 1.90 O7, Tb2Ru 0.05 Ir 1.95 O7 A combination of one or more kinds.

15. The anode catalyst layer for a water electrolysis membrane electrode according to claim 13, wherein, In the molecular formula of the ruthenium-iridium-terbium catalyst, 0.4 ≤ x ≤ 1.

6.

16. The anode catalyst layer for a water electrolysis membrane electrode according to claim 1, wherein, The ruthenium-iridium-terbium catalyst is in particulate form with a particle size of 40-180 nm.

17. The anode catalyst layer for a water electrolysis membrane electrode according to claim 1, wherein, The ionomer is a perfluorosulfonic acid resin.

18. The anode catalyst layer for a water electrolysis membrane electrode according to claim 1, wherein, In use, the first sublayer is located on the surface of the proton exchange membrane, and from there outwards are the second to Nth sublayers.

19. A method for preparing the anode catalyst layer for a water electrolysis membrane electrode according to any one of claims 1-18, comprising the following steps: S1. Preparation of anode catalyst slurry: Water, ionomer, and liquid alcohol are mixed to obtain a dispersion; the anode catalyst is added to the dispersion in portions to disperse it, thereby obtaining the anode catalyst slurry corresponding to the first sublayer; Repeat this step to obtain the anode catalyst slurry corresponding to the 2nd to Nth sublayers; S2. Preparation of the anode catalyst layer: The anode catalyst slurry corresponding to the first sublayer is coated onto the surface of the matrix membrane by spraying or coating to obtain the first sublayer. Then, the anode catalyst slurry corresponding to the second sublayer is coated onto the surface of the first sublayer. The coating process is repeated until the Nth sublayer is obtained, thereby forming the anode catalyst layer for the water electrolysis membrane electrode on the surface of the matrix membrane.

20. The preparation method according to claim 19, wherein, Step S1 includes: S11. Place water in the inner cavity of the jacketed container and connect ice water to the outer cavity of the jacketed container for circulating cooling. S12. Add ionomer and liquid alcohol to the inner cavity of the jacketed container in sequence to disperse them and obtain a dispersion. S13. The anode catalyst is added to the dispersion in multiple portions for further dispersion to obtain the anode catalyst slurry corresponding to the first sublayer; this step is repeated to obtain the anode catalyst slurry corresponding to the second to Nth sublayers.

21. The preparation method according to claim 20, wherein, The dispersion is achieved by an ultrasonic crusher, a high-energy ball mill, a high-pressure homogenizer, or an ultrasonic cell pulverizer.

22. The preparation method according to claim 21, wherein, In steps S12 and S13, the ultrasonic crusher has a power of 300-600W, the high-energy ball mill has a rotation speed of 1000-1500rpm, the high-pressure homogenizer has a dispersion pressure of 15000psi-17000psi, and the ultrasonic cell pulverizer has a power of 600-1000W. And / or, in step 12, the dispersion time is 0.5-1 hour; And / or, in step 13, the dispersion time is 1-2 hours.

23. The preparation method according to claim 19 or 20, wherein, Based on the mass of the anode catalyst slurry (100%), the anode catalyst slurry contains: 0.5-30 wt% anode catalyst and 0.2-20% ionomer.

24. The preparation method according to claim 23, wherein, The ionomer is a perfluorosulfonic acid resin solution, and the concentration of the perfluorosulfonic acid resin solution is 5-20 wt%. And / or, the liquid alcohol is selected from one or more combinations of ethanol, propanol, butanol and isopropanol; And / or, the volume ratio of water to liquid alcohol is 1:0.1-8.

25. A membrane electrode, wherein, The membrane electrode comprises a proton exchange membrane, an anode catalyst layer, and a cathode catalyst layer; The anode catalyst layer is the anode catalyst layer for water electrolysis membrane electrode as described in any one of claims 1-18; Among them, starting from the proton exchange membrane, the sublayer numbers of the anode catalyst layer increase sequentially.

26. The membrane electrode according to claim 25, wherein, The cathode catalyst of the cathode catalyst layer is a Pt / C catalyst.

27. The membrane electrode according to claim 26, wherein, Based on the area of ​​the cathode catalyst layer, the Pt content of the cathode catalyst layer is 0.1-1.0 mg / cm². 2 .

28. The membrane electrode according to claim 27, wherein, Based on the area of ​​the cathode catalyst layer, the content of Pt / C catalyst in the cathode catalyst layer is 0.2-0.8 mg / cm². 2 .

29. The membrane electrode according to claim 26, wherein, Based on the area of ​​the cathode catalyst layer, the Pt content of the cathode catalyst layer is 0.05-0.4 mg / cm². 2 .

30. The membrane electrode according to claim 29, wherein, Based on the area of ​​the cathode catalyst layer, the Pt content of the cathode catalyst layer is 0.10-0.20 mg / cm². 2 .

31. The membrane electrode according to claim 26, wherein, Based on the mass of the Pt / C catalyst being 100%, the Pt element content in the Pt / C catalyst is 10-20%.

32. The membrane electrode according to claim 31, wherein, Based on the mass of the Pt / C catalyst being 100%, the Pt element content in the Pt / C catalyst is 5-40%.

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