A self-supporting catalytic electrode and a method of making and using the same

Abstract

This invention provides a self-supporting catalytic electrode, its preparation method, and its applications. The self-supporting catalytic electrode comprises a composite substrate and noble metal particles supported on the surface of the composite substrate. The composite substrate includes a three-dimensional ordered porous support substrate and a two-dimensional active layer located on the surface of the three-dimensional ordered porous support substrate. The three-dimensional ordered porous support substrate comprises a MAX phase and a glassy carbon reinforcing phase, and the two-dimensional active layer comprises MXene. The self-supporting catalytic electrode provided by this invention not only effectively solves the problem of catalyst powdering but also avoids problems such as electrode polarization, uneven dispersion of active components, and loss of electrochemical active surface area caused by the use of binders. This improves the utilization rate of active components and the electrode reaction kinetics rate, thereby enhancing catalytic activity and stability.

Description

Technical Field

[0001] This invention belongs to the field of water electrolysis for hydrogen production technology, and relates to a self-supporting catalytic electrode, its preparation method, and its applications. Background Technology

[0002] Hydrogen production through water electrolysis has attracted widespread attention from academia and industry due to its advantages such as high hydrogen purity and clean, environmentally friendly production. However, water electrolysis is a chemical process involving multiple elementary reactions, which has drawbacks such as high thermodynamic energy barriers and relatively slow kinetics. Although commonly used noble metal Pt electrocatalysts can effectively improve hydrogen production efficiency, their high material cost makes large-scale application difficult.

[0003] Constructing heterogeneous platinum-based nanocatalysts in the hydrogen evolution reaction (HER) system can maximize catalyst activity and durability while minimizing platinum resource consumption. Nano / atomic platinum is frequently used on carbon-based materials due to its excellent electrical conductivity and chemical stability. These carbon materials include, but are not limited to, carbon black, graphene, and porous carbon. For example, CN104258847A discloses a platinum-carbon composite nanocatalyst, its preparation method, and its applications. The catalyst is prepared by loading platinum onto a surface-modified carbon material to obtain the platinum-carbon composite nanocatalyst; the surface-modified carbon material is rich in electron-deficient surface defects and electron-deficient oxygen-containing functional groups. However, these chemically inert carbon-based materials cannot reduce Pt using wet chemical methods, requiring additional reducing agents or complex post-processing to prepare Pt / C electrocatalysts. This process introduces polymer binders, which block active sites, inhibit ion diffusion, and increase electron transfer resistance.

[0004] Meanwhile, most traditional catalytic materials exist in powder form, requiring binders to fix them onto the hydrogen production electrode. For example, CN115832341A discloses a method for preparing a platinum-carbon catalyst electrode, which involves slurry preparation and electrode fabrication to obtain an electrode loaded with a platinum-carbon catalyst. The slurry-based electrode preparation method affects the sufficient contact between the catalyst and the electrolyte, reducing the effective electrochemical active area. Furthermore, the use of organic binders increases the internal resistance of the electrode, blocking certain reactive sites and deteriorating the actual catalytic performance of the material.

[0005] Therefore, how to reduce the post-processing steps after the catalyst is prepared, while improving the catalytic activity, is an urgent technical problem to be solved. Summary of the Invention

[0006] The purpose of this invention is to provide a self-supporting catalytic electrode, its preparation method, and its applications. The self-supporting catalytic electrode provided by this invention not only effectively solves the problem of catalyst powdering but also avoids issues such as electrode polarization, uneven dispersion of active components, and loss of electrochemical active surface area caused by the use of binders. This improves the utilization rate of active components and the electrode reaction kinetics rate, thereby enhancing catalytic activity and stability.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a self-supporting catalytic electrode, the self-supporting catalytic electrode comprising a composite substrate and noble metal particles loaded on the surface of the composite substrate, the composite substrate comprising a three-dimensional ordered porous support substrate and a two-dimensional active layer located on the surface of the three-dimensional ordered porous support substrate; wherein, the three-dimensional ordered porous support substrate comprises a MAX phase and a glassy carbon reinforced phase, and the two-dimensional active layer comprises MXene.

[0009] The self-supporting catalytic electrode provided by this invention has a multi-level porous structure with macroscopic order and microscopic disorder. Specifically, on a macroscopic scale, after the organic template is removed, the substrate has a clear and uniform mesh structure. The porous structure consists of approximately square macroscopic pores (side length about 1-2 mm), hollow pores generated at the center of the pore ribs after template pyrolysis, and micropores formed by gas overflow during template pyrolysis and subsequent etching.

[0010] The self-supporting catalyst electrode provided by this invention features a three-dimensional ordered porous structure composed of MAX phase material and glassy carbon reinforcement in the support layer. This structure exhibits excellent heat transfer and electron transport capabilities, as well as high mechanical properties and corrosion resistance. Furthermore, its combination with MXene in the two-dimensional active layer increases the specific surface area and electrical conductivity of the substrate layer. The controllable thickness of MXene and the abundance of active binding sites allow for uniform dispersion of noble metal particles on the surface of the two-dimensional active layer, improving the utilization efficiency of the noble metal catalyst and reducing its loading. This invention, through the synergistic cooperation of the above structures, constructs an integral self-supporting catalytic electrode that can be directly used in electrocatalytic hydrogen production reaction systems. This not only effectively solves the problem of catalyst powdering but also avoids issues such as electrode polarization, uneven dispersion of active components, and loss of electrochemical active surface area caused by binders. This improves the utilization rate of active components and electrode reaction kinetics, enhancing catalytic activity and stability.

[0011] In this invention, if the substrate does not contain a two-dimensional active layer, it will result in a lack of active sites and a reduction in the electrochemical active area. If the substrate only contains a two-dimensional active layer and does not contain a three-dimensional ordered porous support layer, it will be impossible to construct a high-strength, high-stability self-supporting catalytic electrode. Furthermore, MXene material has poor conductivity and cannot be directly used as a conductive substrate.

[0012] Preferably, the precious metal particles include any one or a combination of at least two of platinum, ruthenium, or lutetium.

[0013] Preferably, the loading of the precious metal particles is 0.25–0.75 mg / cm³. 2 For example, 0.25 mg / cm³ 2 0.3 mg / cm 2 0.35 mg / cm 2 0.4 mg / cm 2 0.45 mg / cm 2 0.5 mg / cm 2 0.55 mg / cm 2 0.6 mg / cm 2 0.65 mg / cm 2 0.7 mg / cm 2 Or 0.75 mg / cm 2 wait.

[0014] In this invention, the amount of precious metal loading does not need to be excessive to achieve water decomposition under low overpotential, thereby reducing application costs.

[0015] Preferably, the porosity of the three-dimensional ordered porous support substrate is 75% to 90%, such as 75%, 80%, 85%, or 90%.

[0016] In this invention, if the porosity of the three-dimensional ordered porous support substrate is too large, it will lead to a decrease in mechanical strength, while if the porosity is too small, it will affect the contact area between the catalytic electrode and the electrolyte.

[0017] Preferably, the MAX material in the MAX phase includes any one or a combination of at least two of Ti3AlC2, Ti2AlC, or Ti3AlN2.

[0018] Preferably, the glassy carbon reinforcing phase is generated in situ in the three-dimensional ordered porous support substrate.

[0019] In this invention, the glassy carbon reinforcing phase is part of the framework of the three-dimensional ordered porous support substrate, which plays a role in improving the mechanical properties and corrosion resistance of the support layer.

[0020] Preferably, the MXene includes any one or a combination of at least two of Ti3C2, Ti2C, or Ti3N2.

[0021] In a second aspect, the present invention provides a method for preparing a self-supporting catalytic electrode as described in the first aspect, the method comprising the following steps:

[0022] (1) Mix MAX phase ceramic powder, resin and solvent to obtain a mixed slurry, immerse an ordered porous template in the mixed slurry and sinter it to obtain a three-dimensional ordered porous support substrate.

[0023] (2) The three-dimensional ordered porous support substrate described in step (1) is subjected to chemical wet etching to obtain a composite substrate;

[0024] (3) The composite substrate, noble metal salt and solvent described in step (2) are mixed and subjected to a solvothermal reaction to obtain the self-supporting catalytic electrode.

[0025] The preparation method provided by this invention selects a three-dimensional ordered porous template as a template and resin as a binder. A template replication method is used to construct the support layer of the three-dimensional ordered porous structure. The template and resin are pyrolyzed to introduce a glassy carbon reinforcing phase in situ into the MAX phase ceramic powder, which enhances the mechanical properties and corrosion resistance. Using the support layer as part of the substrate, before wet loading of noble metal particles, an MXene two-dimensional active layer is generated in situ etched on the surface of the three-dimensional ordered porous substrate layer. This promotes better dispersion and anchoring of noble metal nanoparticles on the substrate surface. At the same time, since MXene itself has reducing properties, no additional alkaline solvent needs to be added during the solvothermal process, thus avoiding the introduction of impurity elements. Finally, a self-supporting structure that can be directly used as an electrode structure is obtained.

[0026] In this invention, if in-situ etching is not performed before wet loading of noble metal particles, MXene with active sites cannot be obtained, thus affecting the high dispersibility of the metal particles.

[0027] In step (1) of this invention, a resin with good adhesion and high carbonization rate can be selected.

[0028] Preferably, in step (1), the mass ratio of the MAX phase ceramic powder to the resin is 50% or 75%, for example, 50%, 55%, 60%, 65%, 70% or 75%.

[0029] In this invention, if the mass ratio of MAX phase ceramic powder to resin is too large, the glass carbon content will decrease, thus affecting its mechanical strength. If the mass ratio is too small, the glass carbon content will be too high, affecting the in-situ etching growth of MXene in the later stage.

[0030] Preferably, the ordered porous template in step (1) includes an ordered porous PLA template.

[0031] Preferably, the mixing in step (1) further includes a dispersant.

[0032] Preferably, the impregnation in step (1) includes repeated impregnation.

[0033] Preferably, the impregnated material described in step (1) is centrifuged and dried.

[0034] Preferably, the sintering in step (1) is carried out under a protective atmosphere.

[0035] In this invention, a glassy carbon-reinforced phase was obtained in situ through pyrolysis under a protective atmosphere.

[0036] Preferably, the sintering temperature in step (1) is 650 to 850°C, for example, 650°C, 700°C, 750°C, 800°C or 850°C.

[0037] Preferably, the sintering time in step (1) is 15 to 20 hours, such as 15 hours, 16 hours, 17 hours, 18 hours, 19 hours or 20 hours.

[0038] Preferably, the etching solution used in step (2) for chemical wet etching includes a hydrofluoric acid solution.

[0039] Preferably, the mass fraction of the chemical wet etching in step (2) is 16 to 40 wt%, such as 16 wt%, 18 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, or 40 wt%.

[0040] Preferably, the chemical wet etching time in step (2) is 15 to 50 hours, such as 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours or 50 hours.

[0041] Preferably, the temperature of the solvothermal reaction in step (3) is 150 to 180°C, for example, 150°C, 160°C, 170°C or 180°C.

[0042] Preferably, the solvothermal reaction time in step (3) is 3 to 5 hours, for example, 3 hours, 4 hours or 5 hours.

[0043] Preferably, the solvent in step (3) includes ethanol and polyethylene glycol.

[0044] In this invention, polyethylene glycol is added as a solvent during the solvothermal process, which can change the supersaturation and is beneficial to hydrothermal growth.

[0045] As a preferred technical solution, the preparation method includes the following steps:

[0046] (1) Mix MAX phase ceramic powder, resin, dispersant and solvent to obtain a mixed slurry, immerse an ordered porous organic template in the mixed slurry, centrifuge and dry, and sinter under a protective atmosphere to obtain a three-dimensional ordered porous support substrate;

[0047] (2) The three-dimensional ordered porous support layer described in step (1) is subjected to chemical wet etching treatment with hydrofluoric acid solution with a mass concentration of 16-40 wt% for 15-50 h to obtain a composite substrate;

[0048] (3) The composite substrate, noble metal salt and solvent described in step (2) are mixed and subjected to a solvothermal reaction to obtain the self-supporting catalytic electrode.

[0049] Thirdly, the present invention provides a use of the self-supporting catalytic electrode as described in the first aspect, the use including using the self-supporting catalytic electrode for hydrogen production by water electrolysis.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] (1) The self-supporting catalytic electrode provided by the present invention can not only effectively solve the problem of catalyst powdering, but also avoid the problems of electrode polarization, uneven dispersion of active components and loss of electrochemical active surface area caused by the use of binders, thereby improving the utilization rate of active components and electrode reaction kinetics rate, and enhancing catalytic activity and stability.

[0052] (2) The preparation method provided by the present invention selects a three-dimensional ordered porous template as a template and resin as a binder. The template replication method is used to construct the support layer of the three-dimensional ordered porous structure. The template and resin are pyrolyzed to introduce glassy carbon reinforcing phase in situ into the MAX phase ceramic powder, which enhances mechanical properties and corrosion resistance. With the support layer as part of the substrate, before wet loading of noble metal particles, the surface of the three-dimensional ordered porous substrate is etched in situ to generate a two-dimensional active layer of MXene, which can promote better dispersion and anchoring of noble metal nanoparticles on the substrate surface. At the same time, since MXene itself has reducing properties, no additional alkaline solvent needs to be added during the solvothermal process, thereby avoiding the introduction of impurity elements. Finally, a self-supporting structure that can be directly used as an electrode structure is obtained. Attached Figure Description

[0053] Figure 1 This is a macroscopic schematic diagram of the self-supporting catalytic electrode provided in Example 1.

[0054] Figure 2 SEM image of the surface of the self-supporting catalytic electrode provided in Example 1.

[0055] Figure 3 SEM image of the surface of the self-supporting catalytic electrode provided in Example 1.

[0056] Figure 4 The SLV curves of the self-supporting catalytic electrodes provided in Example 1 are compared with those of Comparative Examples 1 and 3.

[0057] Figure 5The stability test diagram is for the self-supporting catalytic electrode provided in Example 1. Detailed Implementation

[0058] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0059] Example 1

[0060] This embodiment provides a self-supporting catalytic electrode, which includes a composite substrate and platinum nanoparticles (with a loading of 0.5 mg / cm²) loaded on the surface of the composite substrate. 2 The composite substrate comprises a three-dimensional ordered porous support substrate (porosity 85%) and a two-dimensional active layer located on the surface of the three-dimensional ordered porous support substrate; wherein the three-dimensional ordered porous support substrate comprises Ti3AlC2 and glassy carbon reinforcing phase (Ti3AlC2@C), and the two-dimensional active layer comprises Ti3C2.

[0061] The method for preparing the self-supporting catalytic electrode is as follows:

[0062] (1) Take 200g of Ti3AlC2 powder with an average particle size of <3μm, slowly add it to an ethanol solution containing 50wt% phenolic resin, stir for 30min, then add 0.1g of CMC and PEG in sequence, stir for 30min to obtain a uniform Ti3AlC2 slurry, and store it for later use.

[0063] An ordered porous PLA template (with square pores having a side length of 1 mm) was immersed in a 1 mol / L NaOH solution for 24 hours. Afterward, it was removed and ultrasonically cleaned with deionized water until the pH reached 7. The cleaned template was then placed in a 70°C drying oven and dried for 5 hours. It was then stored for later use.

[0064] (2) The pretreated ordered porous PLA template was immersed in a slurry containing Ti3AlC2 for 1 min and then immediately removed. It was centrifuged at 286 / min to remove excess slurry. After centrifugation, it was air-dried at room temperature for 30 min and then placed in an oven at 100℃ for 30 min. The above immersion steps were repeated 15 times to obtain a porous green body. The obtained porous green body was placed in a decomposition furnace and degreased at 850℃ for 2 h under a nitrogen atmosphere at a heating rate of 1℃ / min. Then it was cooled with the furnace and the sample was removed. At this time, a three-dimensional ordered porous Ti3AlC2@C (supporting substrate, labeled 3DNP-TC) with high porosity can be obtained.

[0065] (3) Take 10 ml of HF solution with a mass fraction of 40 wt%, slowly add it to 15 ml of deionized water, stir magnetically for 30 min to dissolve it completely, and obtain a diluted HF solution with a mass fraction of 16 wt%. Place the prepared porous Ti3AlC2@C in the diluted HF solution and place it at room temperature for 24 h. Then take out the porous sample, rinse it with deionized water several times, and dry it to obtain a three-dimensional ordered porous Ti3C2 / Ti3AlC2@C composite substrate (labeled as 3DNP-MTC) with Ti3C2 on the surface.

[0066] (4) Take 10 ml of ethanol and 10 ml of polyethylene glycol solution and mix and stir for 10 min. Then slowly add 0.01 mol / L chloroplatinic acid and stir for 30 min. Transfer the mixed solution to the inner liner of the hydrothermal reactor and place the composite substrate layer into the inner liner of the hydrothermal reactor. Finally, hydrothermally heat at 180℃ for 5 h. After cooling, wash with deionized water by centrifugation 5 times and dry to obtain the self-supporting catalytic electrode (Pt@3DNP-MTC).

[0067] Figure 1 A macroscopic schematic diagram of the self-supporting catalytic electrode provided in Example 1 is shown. Figure 2 and Figure 3 SEM images of the self-supporting catalytic electrode provided for Example 1 at different magnifications are shown. Figures 1-3 As can be seen, on a macroscopic scale, the electrode has a clear and uniform mesh structure. On a microscopic scale, the electrode surface is uniformly loaded with Pt particles, and during the hydrothermal process, the overflow of gas creates a large number of mesopores on the surface, which facilitates the exposure of more active sites.

[0068] Example 2

[0069] This embodiment provides a self-supporting catalytic electrode, which includes a composite substrate and platinum nanoparticles (with a loading of 0.75 mg / cm²) loaded on the surface of the composite substrate. 2 The composite substrate comprises a three-dimensional ordered porous support substrate (porosity 95%) and a two-dimensional active layer located on the surface of the three-dimensional ordered porous support substrate; wherein the three-dimensional ordered porous support substrate comprises Ti2AlC and a glassy carbon reinforcing phase (Ti2AlC@C), and the two-dimensional active layer comprises Ti2C.

[0070] The method for preparing the self-supporting catalytic electrode is as follows:

[0071] (1) Take 200g of Ti2AlC powder with an average particle size of <3μm, slowly add it to an ethanol solution containing 50wt% phenolic resin, stir for 30min, then add 0.1g of CMC and PEG in sequence, stir for 30min to obtain a uniform Ti2AlC slurry, and store it for later use.

[0072] An ordered porous PLA template (with square pores having a side length of 1 mm) was immersed in a 1 mol / L NaOH solution for 24 hours. Afterward, it was removed and ultrasonically cleaned with deionized water until the pH reached 7. The cleaned template was then placed in a 70°C drying oven and dried for 5 hours. It was then stored for later use.

[0073] (2) The pretreated ordered porous polymer template (PLA template) was immersed in a slurry containing Ti2AlC for 1 min and then immediately removed. It was centrifuged at 286 / min to remove excess slurry. After centrifugation, it was air-dried at room temperature for 30 min and then placed in an oven at 100℃ for 30 min. The above immersion steps were repeated 15 times to obtain a porous green body. The obtained porous green body was placed in a decomposition furnace and degreased at 850℃ for 2 h under a nitrogen atmosphere at a heating rate of 1℃ / min. Then it was cooled with the furnace and the sample was removed. At this time, a three-dimensional ordered porous Ti2AlC@C (supporting substrate) with high porosity can be obtained.

[0074] (3) Take 10 ml of HF solution with a mass fraction of 40 wt%, slowly add 15 ml of deionized water, and stir magnetically for 30 min to dissolve it completely, so as to obtain a diluted HF solution with a mass fraction of 16 wt%. Place the prepared porous Ti2AlC@C in the diluted HF solution and place it at room temperature for 15 h. Then take out the porous sample, rinse it with deionized water several times, and dry it to obtain a three-dimensional ordered porous Ti2C / Ti2AlC@C composite substrate with Ti3C2 activity on the surface.

[0075] (4) Take 10 ml of ethanol and 10 ml of polyethylene glycol solution and mix and stir for 10 min. Then slowly add 0.01 mol / L chloroplatinic acid and stir for 30 min. Transfer the mixed solution to the inner liner of the hydrothermal reactor and place the composite substrate layer into the inner liner of the hydrothermal reactor. Finally, hydrothermally heat at 180℃ for 5 h. After cooling, wash with deionized water 5 times by centrifugation and dry to obtain the self-supporting catalytic electrode.

[0076] Example 3

[0077] This embodiment provides a self-supporting catalytic electrode, which includes a composite substrate and platinum nanoparticles (with a loading of 0.25 mg / cm³) loaded on the surface of the composite substrate. 2The composite substrate comprises a three-dimensional ordered porous support layer (porosity 75%) and a two-dimensional active layer located on the surface of the three-dimensional ordered porous support layer; wherein the three-dimensional ordered porous support layer comprises Ti3AlN2 and a glassy carbon reinforcing phase (Ti3AlN2@C), and the two-dimensional active layer comprises Ti3N2.

[0078] The method for preparing the self-supporting catalytic electrode is as follows:

[0079] (1) Take 200g of Ti3AlN2 powder with an average particle size of <3μm, slowly add it to an ethanol solution containing 50wt% phenolic resin, stir for 30min, then add 0.1g of CMC and PEG in sequence, stir for 30min to obtain a uniform Ti3AlN2 slurry, and store it for later use.

[0080] An ordered porous PLA template (with square pores having a side length of 1 mm) was immersed in a 1 mol / L NaOH solution for 24 hours. Afterward, it was removed and ultrasonically cleaned with deionized water until the pH reached 7. The cleaned template was then placed in a 70°C drying oven and dried for 5 hours. It was then stored for later use.

[0081] (2) The pretreated ordered porous polymer template (PLA template) was immersed in a slurry containing Ti3AlN2 for 1 min and then immediately removed. It was centrifuged at 286 / min to remove excess slurry. After centrifugation, it was air-dried at room temperature for 30 min and then placed in an oven at 100℃ for 30 min. The above immersion steps were repeated 15 times to obtain a porous green body. The obtained porous green body was placed in a decomposition furnace and degreased at 850℃ for 2 h under a nitrogen atmosphere at a heating rate of 1℃ / min. Then it was cooled with the furnace and the sample was removed. At this time, a three-dimensional ordered porous Ti3AlN2@C (support layer) with high porosity can be obtained.

[0082] (3) Take 10 ml of HF solution with a mass fraction of 40 wt%, slowly add 15 ml of deionized water, and stir magnetically for 30 min to dissolve it completely, so as to obtain a diluted HF solution with a mass fraction of 16 wt%. Place the prepared porous Ti3AlN2@C in the diluted HF solution and place it at room temperature for 50 h. Then take out the porous sample, rinse it with deionized water several times, and dry it to obtain a three-dimensional ordered porous Ti3N2 / Ti3AlN2@C composite substrate layer with Ti3C2 activity on the surface.

[0083] (4) Take 10 ml of ethanol and 10 ml of polyethylene glycol solution and mix and stir for 10 min. Then slowly add 0.01 mol / L chloroplatinic acid and stir for 30 min. Transfer the mixed solution to the inner liner of the hydrothermal reactor and place the composite substrate layer into the inner liner of the hydrothermal reactor. Finally, hydrothermally heat at 180℃ for 5 h. After cooling, wash with deionized water 5 times by centrifugation and dry to obtain the self-supporting catalytic electrode.

[0084] Example 4

[0085] The difference between this embodiment and Embodiment 1 is that the etching time for the three-dimensional ordered porous support substrate in this embodiment is 12 hours.

[0086] The remaining preparation methods and parameters are consistent with those in Example 1.

[0087] Example 5

[0088] The difference between this embodiment and Embodiment 1 is that the etching time for the three-dimensional ordered porous support substrate in this embodiment is 60 hours.

[0089] The remaining preparation methods and parameters are consistent with those in Example 1.

[0090] Comparative Example 1

[0091] The difference between this comparative example and Example 1 is that the self-supporting catalytic electrode (labeled as Pt@3DNP-TC) provided in this comparative example does not include a two-dimensional active layer, and step (3) is not performed in the preparation method. The loading method in step (4) is as follows: 10 ml of ethanol and 10 ml of polyethylene glycol are mixed and stirred for 10 min. Then, 0.02 mol / L chloroplatinic acid is added and stirred for another 30 min. Then, NaOH is slowly added to adjust the pH of the solution to 10 to obtain solution A. Solution A is then placed in different hydrothermal reactors together with the substrate. Finally, the reactor is hydrothermally heated at 180°C for 5 h. After cleaning and drying, a catalytic electrode structure with Pt metal on the surface is obtained.

[0092] The remaining preparation methods and parameters are consistent with those in Example 1.

[0093] Comparative Example 2

[0094] The difference between this comparative example and Example 1 is that the three-dimensional ordered porous support layer in this comparative example does not contain glassy carbon.

[0095] In the preparation method, the obtained porous green body is placed in a decomposition furnace, heated at a rate of 1℃ / min in an air atmosphere, and degreased at 850℃ for 2 hours.

[0096] The remaining preparation methods and parameters are consistent with those in Example 1.

[0097] Comparative Example 3

[0098] This comparative example provides a catalytic electrode, which is a pure commercial platinum sheet.

[0099] Figure 4 The SLV curves of the self-supporting catalytic electrodes provided in Example 1, Comparative Examples 1 and 3 are shown in the comparison graph. Figure 4 It can be seen that the self-supporting electrode structure provided by the present invention has the lowest overpotential, only 46mV, which is lower than the 75mV of the Pt sheet, showing considerable hydrogen evolution performance.

[0100] Figure 5 The stability test diagram of the self-supporting catalytic electrode provided in Example 1 is shown. Figure 5 It can be seen that the self-supporting electrode structure provided by the present invention has a high repeatability of SLV curve after 10,000 cycles, and the electrode performance has not significantly degraded, indicating that the electrode has good stability.

[0101] The catalytic performance of the self-supporting catalytic electrodes provided in Examples 1-5 and Comparative Examples 1-3 was tested under the following conditions: the electrolyte was 0.5M H2SO4 solution. The scan rate for SLV testing was 1mV / s, and the scan range was -0.7V to 0.1V vs. RHE. The test results are shown in Table 1.

[0102] Table 1

[0103] Overpotential (mV) Tafel slope (Mv / dec) Example 1 46 21 Example 2 52 24 Example 3 63 31 Example 4 86 45 Example 6 93 62 Comparative Example 1 104 72 Comparative Example 2 153 93 Comparative Example 3 75 33

[0104] The data from Examples 1, 4, and 5 show that excessive etching time on the three-dimensional ordered porous support substrate is detrimental to the kinetics of the catalytic reaction, while excessively short etching time will affect the formation of the MXene active layer.

[0105] The data from Example 1 and Comparative Example 1 show that the composite substrate does not contain a two-dimensional active layer, which makes it impossible to reduce the overpotential and thus cannot improve the catalytic reaction kinetics.

[0106] The data from Example 1 and Comparative Example 2 show that if the three-dimensional ordered porous support layer does not contain a glassy carbon reinforcing phase, a self-supporting catalytic electrode with high stability and high catalytic activity cannot be obtained.

[0107] The data from Example 1 and Comparative Example 3 show that the catalytic electrode provided by the present invention has high stability and good catalytic activity.

[0108] In summary, the self-supporting catalyst electrode provided by this invention features a three-dimensional ordered porous structure with MAX material and glassy carbon reinforcement in the support layer. This structure exhibits excellent heat transfer and electron transport capabilities, as well as high mechanical properties and corrosion resistance. Furthermore, its combination with MXene in the two-dimensional active layer increases the specific surface area and electrical conductivity of the substrate layer. The controllable thickness of MXene and the abundance of active binding sites allow for uniform dispersion of noble metal particles on the surface of the two-dimensional active layer, improving the utilization efficiency of the noble metal catalyst and reducing its loading. This invention, through the synergistic cooperation of the above structures, constructs an integral self-supporting catalytic electrode that can be directly used in electrocatalytic hydrogen production reaction systems. This not only effectively solves the problem of catalyst powdering but also avoids issues such as electrode polarization, uneven dispersion of active components, and loss of electrochemical active surface area caused by binders. This improves the utilization rate of active components and electrode reaction kinetics, enhancing catalytic activity and stability.

[0109] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A self-supporting catalytic electrode, characterized in that, The self-supporting catalytic electrode includes a composite substrate and noble metal particles loaded on the surface of the composite substrate. The composite substrate includes a three-dimensional ordered porous support substrate and a two-dimensional active layer located on the surface of the three-dimensional ordered porous support substrate. The three-dimensional ordered porous support substrate includes a MAX phase and a glassy carbon reinforced phase, and the two-dimensional active layer includes MXene. The loading of the precious metal particles is 0.25~0.75 mg / cm³. 2 ; The porosity of the three-dimensional ordered porous support substrate is 75-90%; The self-supporting catalytic electrode is used for hydrogen production by water electrolysis.

2. The self-supporting catalytic electrode according to claim 1, characterized in that, The precious metal particles include any one or a combination of at least two of platinum, ruthenium, or lutetium.

3. The self-supporting catalytic electrode according to claim 1, characterized in that, The MAX material in the MAX phase includes any one or a combination of at least two of Ti3AlC2, Ti2AlC, or Ti3AlN2.

4. The self-supporting catalytic electrode according to claim 1, characterized in that, The glassy carbon reinforced phase is generated in situ in the three-dimensional ordered porous support substrate.

5. The self-supporting catalytic electrode according to claim 1, characterized in that, The MXene includes any one or a combination of at least two of Ti3C2, Ti2C, or Ti3N2.

6. A method for preparing a self-supporting catalytic electrode as described in any one of claims 1-5, characterized in that, The preparation method includes the following steps: (1) Mix MAX phase ceramic powder, resin and solvent to obtain a mixed slurry, immerse an ordered porous template in the mixed slurry and sinter it to obtain a three-dimensional ordered porous support substrate; (2) The three-dimensional ordered porous support substrate described in step (1) is subjected to chemical wet etching to obtain a composite substrate; (3) The composite substrate, noble metal and solvent described in step (2) are mixed and subjected to a solvothermal reaction to obtain the self-supporting catalytic electrode.

7. The method for preparing a self-supporting catalytic electrode according to claim 6, characterized in that, In step (1), the mass ratio of the MAX phase ceramic powder to the resin is 50-75%.

8. The method for preparing a self-supporting catalytic electrode according to claim 6, characterized in that, The ordered porous template in step (1) includes an ordered porous PLA template.

9. The method for preparing a self-supporting catalytic electrode according to claim 6, characterized in that, The mixed slurry in step (1) also includes a dispersant.

10. The method for preparing a self-supporting catalytic electrode according to claim 6, characterized in that, The impregnation in step (1) includes repeated impregnation.

11. The method for preparing a self-supporting catalytic electrode according to claim 6, characterized in that, The impregnated material described in step (1) is centrifuged and dried.

12. The method for preparing a self-supporting catalytic electrode according to claim 6, characterized in that, The sintering in step (1) is carried out under a protective atmosphere.

13. The method for preparing a self-supporting catalytic electrode according to claim 6, characterized in that, The sintering temperature in step (1) is 650~850℃.

14. The method for preparing a self-supporting catalytic electrode according to claim 6, characterized in that, The sintering time in step (1) is 15~20h.

15. The method for preparing a self-supporting catalytic electrode according to claim 6, characterized in that, The etching solution used in step (2) of the chemical wet etching includes a hydrofluoric acid solution.

16. The method for preparing a self-supporting catalytic electrode according to claim 6, characterized in that, The mass fraction of the etching solution used in step (2) of the chemical wet etching process is 16~40wt%.

17. The method for preparing a self-supporting catalytic electrode according to claim 6, characterized in that, The chemical wet etching time in step (2) is 15~50h.

18. The method for preparing a self-supporting catalytic electrode according to claim 6, characterized in that, The temperature of the solvothermal reaction in step (3) is 150~180℃.

19. The method for preparing a self-supporting catalytic electrode according to claim 6, characterized in that, The solvothermal reaction in step (3) takes 3 to 5 hours.

20. The method for preparing a self-supporting catalytic electrode according to claim 6, characterized in that, The solvents in step (3) include ethanol and polyethylene glycol.

21. The method for preparing a self-supporting catalytic electrode according to claim 6, characterized in that, The preparation method includes the following steps: (1) Mix MAX phase ceramic powder, resin, dispersant and solvent to obtain a mixed slurry, immerse an ordered porous organic template in the mixed slurry, centrifuge and dry, and sinter under a protective atmosphere to obtain a three-dimensional ordered porous support substrate; (2) The three-dimensional ordered porous support substrate described in step (1) is subjected to chemical wet etching treatment with hydrofluoric acid solution with a mass concentration of 16~40wt% for 15~50h to obtain a composite substrate; (3) The composite substrate, noble metal salt and solvent described in step (2) are mixed and subjected to a solvothermal reaction to obtain the self-supporting catalytic electrode.

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