A three-dimensional porous self-supporting electrode substrate, a preparation method and application thereof

Abstract

The application provides a three-dimensional porous self-supporting electrode substrate and a preparation method and application thereof. The three-dimensional porous self-supporting electrode substrate comprises a three-dimensional porous MAX phase and glassy carbon compounded in the three-dimensional porous MAX phase; the pore structure in the three-dimensional porous MAX phase is macroscopically ordered and microscopically disordered; and the macroscopically ordered pore structure is a through-hole structure. The three-dimensional porous self-supporting electrode substrate of the MAX phase substrate compounded with glassy carbon provided by the application has macroscopic pores and microscopic pores, and the macroscopic pores are orderly distributed, has high cross-linking degree and high connectivity, and leaves space for the shrinkage or expansion of the volume in the charge and discharge process of the electrode. Meanwhile, the three-dimensional porous self-supporting electrode substrate has high compressive strength, a stable structure, good mechanical properties, high acid resistance, strong binding force between the substrate and catalytic particles after loading of the catalytic particles, makes the reaction more stable, and has good catalytic effect on water electrolysis hydrogen production.

Description

Technical Field

[0001] This invention belongs to the field of electrolytic hydrogen production technology through water electrolysis, and relates to a three-dimensional porous self-supporting electrode substrate, its preparation method, and its application. 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 change process involving multiple elementary reactions, which has drawbacks such as high thermodynamic energy barriers and relatively slow kinetics.

[0003] While commonly used precious metal Pt electrocatalysts can effectively improve hydrogen production efficiency, their high material cost makes large-scale application difficult. For example, CN106582712A provides a catalyst for water electrolysis to produce hydrogen, wherein the catalyst is a carbon-supported nano-copper-platinum alloy. The catalyst of this invention has more active sites, improving electrochemical catalytic efficiency; simultaneously, the addition of copper reduces the platinum loading, further lowering costs; due to the synergistic effect between the metals, the platinum-copper alloy can effectively reduce the overpotential of the electrochemical reaction, lower the electrolytic cell voltage, and reduce energy consumption costs.

[0004] Traditional catalytic materials are mostly 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. This slurry coating 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 degrading the actual catalytic performance of the material.

[0005] By constructing an integral self-supporting catalytic electrode that can be directly used in electrocatalytic hydrogen production systems, the problem of catalyst powdering can be effectively solved. Furthermore, it avoids electrode polarization, uneven dispersion of active components, and loss of electrochemical active surface area caused by binders, thereby improving the utilization rate of active materials and the electrode reaction kinetics rate. Currently, the most widely studied metal-based self-supporting catalytic electrodes exhibit low stability in acidic media and are only suitable for alkaline electrolyzers, severely limiting their catalytic efficiency.

[0006] Therefore, how to obtain an electrode structure that is controllable, stable, and has excellent catalytic performance is an urgent technical problem to be solved. Summary of the Invention

[0007] The purpose of this invention is to provide a three-dimensional porous self-supporting electrode substrate, its preparation method, and its applications. The MAX-based three-dimensional porous self-supporting electrode substrate of composite glassy carbon provided by this invention possesses both macroscopic and microscopic pores, with the macroscopic pores orderly distributed, exhibiting high cross-linking degree and high connectivity, providing space for volume contraction or expansion during electrode charging and discharging. It also possesses high compressive strength, structural stability, good mechanical properties, and high acid resistance. After loading catalytic particles, the strong bonding force between the substrate and the catalytic particles makes the reaction more stable, resulting in excellent catalytic effect for hydrogen production via water electrolysis.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a three-dimensional porous self-supporting electrode substrate, the three-dimensional porous self-supporting electrode substrate comprising a three-dimensional porous MAX phase and glassy carbon composite in the three-dimensional porous MAX phase; the pore structure in the three-dimensional porous MAX phase is macroscopically ordered and microscopically disordered; the macroscopically ordered pore structure is a through-hole structure.

[0010] The shape of the macroscopically ordered pore structure provided by this invention is not unique and can be adaptively adjusted according to actual needs, such as honeycomb, circular or matrix shape, etc.

[0011] The three-dimensional porous self-supporting electrode substrate provided by this invention possesses both macroscopic and microscopic pores, with the macroscopic pores distributed in an orderly manner. The pore structure is straight up and down, exhibiting a single-pore direct-entry type with low tortuosity, high cross-linking degree, and high connectivity. It also has high compressive strength and structural stability. Furthermore, the three-dimensional porous MAX phase structure has characteristics such as high specific surface area, high porosity, and permeability. When used as a catalytic electrode, it can not only provide a larger electrochemical reaction area, but the porous structure also leaves space for the volume contraction or expansion during the charge and discharge process of the electrode, making the reaction more stable. After further composite with glassy carbon, its mechanical strength is improved, and its chemical stability in acidic solutions is also enhanced. After loading catalytic particles, it has a good catalytic effect for hydrogen production by water electrolysis.

[0012] In this invention, if the pores in the ordered porous structure are not interconnected, it will affect its specific surface area and reduce the contact area with the electrolyte.

[0013] Preferably, the radially distributed deflection angle in the through-hole structure is 0~30°, such as 0°, 3°, 5°, 8°, 10°, 13°, 15°, 18°, 20°, 23°, 25°, 28° or 30°.

[0014] Preferably, the total planar area of ​​the macroscopically ordered pore structure is 45% to 80% of the area of ​​the same plane of the three-dimensional porous MAX phase, such as 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%.

[0015] Preferably, the porosity of the macroscopically ordered pore structure is 75-90%, such as 75%, 80%, 85%, or 90%.

[0016] In this invention, the total planar area of ​​the macroscopically ordered pore structure and the porosity work together to influence the mechanical strength.

[0017] Preferably, the compressive strength of the three-dimensional porous self-supporting electrode substrate is 1.72±0.47~7.02±0.13MPa, for example.

[0018] Preferably, the MAX material in the three-dimensional porous MAX phase includes any one or a combination of at least two of Ti3AlC2, Ti2AlC, or Ti3AlN2, with Ti3AlC2 being the most preferred.

[0019] In a second aspect, the present invention provides a method for preparing a three-dimensional porous self-supporting electrode substrate as described in the first aspect, the method comprising the following steps:

[0020] MAX phase ceramic powder, binder and solvent are mixed to obtain a mixed slurry. The 3D printing template is immersed in the mixed slurry and debinding reaction is carried out to obtain the three-dimensional porous self-supporting electrode substrate.

[0021] In this invention, by combining 3D printing technology with a template method, a multi-level porous structure with both macroscopic and microscopic pores was obtained. The macroscopic pores were ordered and controllable. Meanwhile, after the debinding reaction, the template was pyrolyzed in an oxygen-free environment, introducing a multi-phase reinforcing phase, glassy carbon, in situ. Glassy carbon has good electrical conductivity and chemical stability. Without affecting the electrical conductivity of the MAX phase porous structure, it can enhance its mechanical properties and improve its chemical stability in acidic solutions. Finally, a substrate with high cross-linking degree and high connectivity, high compressive strength, and a more stable structure was obtained.

[0022] In this invention, if other templates are selected, such as the traditional foam template method, the mechanical properties are poor. At the same time, this method also has problems such as the inability to achieve personalized design and manufacturing of pore structure and size, and it is completely impossible to obtain the high-strength porous MAX phase substrate of this application.

[0023] Preferably, the particle size of the MAX phase ceramic powder is 1~10μm, such as 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm or 10μm.

[0024] Preferably, the weight percentage of the binder is 25-50 wt%, for example, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, or 50 wt%, based on the total weight of the non-MAX phase ceramic powder in the mixed slurry being 100 wt%.

[0025] Preferably, the solvent has a weight percentage of 49-74 wt%, based on the total weight of the non-MAX phase ceramic powder in the mixed slurry being 100 wt%, for example, 49 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, or 74 wt%.

[0026] Preferably, the adhesive comprises a phenolic resin.

[0027] Preferably, the solvent includes ethanol.

[0028] Preferably, the mixed slurry further includes a dispersant.

[0029] Preferably, the dispersant comprises carboxymethyl cellulose and / or polyethylene glycol.

[0030] Preferably, the method for preparing the 3D printing template includes:

[0031] The template substrate is printed using the FDM-3D printing method to obtain a 3D printed template.

[0032] In this invention, fused deposition modeling (FDM) 3D printing is a method that does not rely on lasers as a forming energy source, but heats and melts various filaments to form a structure. It has advantages such as low cost, high precision, and convenient operation. By combining FDM-3D printing technology with the replication template method, a three-dimensional porous self-supporting electrode substrate with a highly cross-linked pore structure can be obtained.

[0033] Preferably, the template substrate comprises any one or a combination of at least two of engineering plastics, polycarbonate, or polylactic acid.

[0034] Preferably, the scanning speed during the printing process is 10~150mm / s, such as 10mm / s, 30mm / s, 50mm / s, 80mm / s, 100mm / s, 130mm / s or 150mm / s.

[0035] Preferably, the flow rate during the printing process is 80-100%, such as 80%, 85%, 90%, 95%, or 100%.

[0036] Preferably, the layer thickness during the printing process is set to 0.05~0.35mm, such as 0.05mm, 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm or 0.35mm.

[0037] Preferably, the size of the hole in the 3D printed template is 0.6~2mm, such as 0.6mm, 1mm, 1.5mm or 2mm.

[0038] Preferably, the diameter of the ribs in the 3D printed template is 0.3~0.6mm, for example, 0.3mm, 0.4mm, 0.5mm or 0.6mm.

[0039] Preferably, the number of impregnations is 10 to 25 times, such as 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25 times.

[0040] Preferably, drying is performed after each impregnation.

[0041] Preferably, the temperature of the degreasing reaction is 650~850℃, such as 650℃, 675℃, 700℃, 725℃, 750℃, 775℃, 800℃, 825℃ or 850℃.

[0042] Preferably, the degreasing reaction is carried out under a protective atmosphere.

[0043] As a preferred technical solution, the preparation method includes the following steps:

[0044] The template substrate is printed using the FDM-3D printing method at a scanning speed of 10~150mm / s and a flow rate of 80~100%. The layer thickness during the printing process is set to 0.05~0.35mm, resulting in a 3D printed template with hole size of 0.6~2mm and rib thickness of 0.3~0.6mm.

[0045] MAX phase ceramic powder, binder and solvent are mixed to obtain a mixed slurry. The 3D printing template is immersed in the mixed slurry 10 to 25 times. After each immersion, it is dried and degreased under a protective atmosphere to obtain the three-dimensional porous self-supporting electrode substrate.

[0046] Thirdly, the present invention provides a three-dimensional porous self-supporting electrode, the three-dimensional porous self-supporting electrode comprising a three-dimensional porous self-supporting electrode substrate as described in the first aspect and catalytic particles loaded on the three-dimensional porous self-supporting electrode substrate.

[0047] In this invention, catalytic particles are further loaded onto the substrate provided in the first aspect, which can directly construct a stable and efficient self-supporting catalytic electrode that can be directly used in an electrocatalytic hydrogen production reaction system.

[0048] Fourthly, the present invention also provides a method for preparing a three-dimensional porous self-supporting electrode as described in the third aspect, the method comprising the following steps:

[0049] The three-dimensional porous self-supporting electrode substrate, metal salt solution, and reducing agent solution are mixed and subjected to a hydrothermal reaction to obtain the three-dimensional porous self-supporting electrode.

[0050] Preferably, the metal salt includes a noble metal salt.

[0051] Preferably, the molar concentration of the metal salt solution is 0.01~0.02 mol / L.

[0052] Preferably, the pH value of the mixed solution is 8 to 13.

[0053] Preferably, the temperature of the hydrothermal reaction is 150~220℃.

[0054] Preferably, the hydrothermal reaction takes 3 to 5 hours.

[0055] Fifthly, the present invention also provides the use of the three-dimensional porous self-supporting electrode as described in the third aspect, the use including using the three-dimensional porous self-supporting electrode for hydrogen production by water electrolysis.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] (1) The three-dimensional porous self-supporting electrode substrate with glassy carbon MAX phase provided by the present invention has macroscopic pores and microscopic pores, and the macroscopic pores are orderly distributed, with high cross-linking degree and high connectivity. It also has high compressive strength, stable structure, high mechanical strength, and good acid corrosion resistance. After loading catalytic particles, the binding force between the substrate and the catalytic particles is strong, and it has a good catalytic effect for hydrogen production by water electrolysis.

[0058] (2) In this invention, by combining 3D printing technology with template method, a multi-level porous structure with both macroscopic and microscopic pores and ordered and controllable macroscopic pores is obtained. At the same time, after the degreasing reaction, the template is pyrolyzed in an oxygen-free environment, and the multiphase reinforcing phase glassy carbon is introduced in situ. Glassy carbon has good conductivity and chemical stability. Without affecting the conductivity of the MAX phase porous substrate, it can enhance its mechanical properties and improve its chemical stability in acidic solutions. Finally, a substrate with high crosslinking degree and high connectivity, high compressive strength and more stable structure is obtained. Attached Figure Description

[0059] Figure 1 The image shows the macroscopic morphology of the three-dimensional porous self-supporting electrode provided in Example 1.

[0060] Figure 2 The three-dimensional porous self-supporting electrode provided in Example 1 Figure 1 A further magnified microscopic image.

[0061] Figure 3 The three-dimensional porous self-supporting electrode provided in Example 1 Figure 1 A further magnified microscopic image.

[0062] Figure 4 This is a comparison diagram of the compressive strength of the three-dimensional porous self-supporting electrodes provided in Example 1 and Comparative Example 2.

[0063] Figure 5 The current density decay diagram is shown for the three-dimensional porous self-supporting electrode provided in Example 1. Detailed Implementation

[0064] 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.

[0065] Example 1

[0066] This embodiment provides a three-dimensional porous self-supporting electrode substrate, which includes a three-dimensional porous Ti3AlC2 phase and glassy carbon (Ti3AlC2@C) composite in the three-dimensional porous Ti3AlC2 phase; the pore structure in the three-dimensional porous Ti3AlC2 phase is macroscopically ordered and microscopically disordered; the macroscopically ordered pore structure is a through-hole structure.

[0067] Among them, the compressive strength of the three-dimensional porous self-supporting electrode substrate, the area ratio of the total planar area of ​​the macroscopically ordered pore structure to the area of ​​the same plane of the three-dimensional porous Ti3AlC2 phase, the porosity of the macroscopically ordered pore structure, and the deflection angle of the radial distribution in the through-hole structure are shown in Table 1.

[0068] The method for preparing the three-dimensional porous self-supporting electrode substrate is as follows:

[0069] (1) First, select PLA filament and use FDM method to print an ordered porous organic template (pore size is 1mm, pore rib thickness is 0.6mm). During the printing process, the parameters are set as follows: layer thickness is 0.35mm, scanning speed is 100mm / s, flow rate is 100%, heated bed temperature is 50℃, and nozzle temperature is 205℃.

[0070] After soaking the 3D printing template in a 1M NaOH solution for 48 hours, it was taken out and ultrasonically cleaned with deionized water until the pH=7. Then, the cleaned template was placed in a drying oven at 70℃ and dried for 5 hours.

[0071] (2) Take 100g of Ti3AlC2 powder and slowly add it to an ethanol solution containing phenolic resin. After stirring for 30min, add CMC and PEG in sequence and stir for 30min to obtain a uniform Ti3AlC2 slurry (in the slurry, which is not composed of Ti3AlC2 powder, polyvinyl alcohol is 25wt%, CMC and PEG are 0.5wt% each, and the rest is ethanol), and store it for later use;

[0072] (3) After soaking the prepared 3D printing template in the slurry containing Ti3AlC2 for 1 min, take it out immediately and place it in a centrifuge at 286 / min to remove excess slurry. After centrifugation, take it out and air dry at room temperature, then put it in an oven at 100℃ for 1 h. Repeat the soaking 25 times to obtain a three-dimensional ordered porous Ti3AlC2 green body containing the template.

[0073] (4) The green sample was placed in a tube furnace and degreased at 800℃ for 15h under an argon atmosphere with a heating rate of 1℃ / min. Finally, it was taken out to obtain a three-dimensional ordered porous Ti3AlC2@C conductive substrate with high porosity.

[0074] Figure 1 A macroscopic morphology diagram of the three-dimensional porous self-supporting electrode provided in Example 1 is shown.

[0075] Figure 2 and Figure 3 The three-dimensional porous self-supporting electrode provided for Example 1 is shown in the figure. Figure 1 A further magnified microscopic image, Figure 2 for Figure 1 Enlarged detail image of the department circled in the box. Figure 3 Then it is Figure 1 A magnified view of the details of the connection between the holes in the image. Figures 1-3 It can be seen that the porous substrate exhibits macroscopic order and microscopic disorder. After pyrolysis, the occupancy of the 3D template disappears, resulting in the formation of highly cross-linked interconnected pores inside the pores.

[0076] Figure 5 The current density decay diagram of the three-dimensional porous self-supporting electrode provided in Example 1 is shown. Figure 5 As can be seen, the self-supporting electrode structure provided by this invention did not show a significant decrease in current density after 100 hours of testing, indicating that it has excellent stability.

[0077] Example 2

[0078] This embodiment provides a three-dimensional porous self-supporting electrode substrate, which includes a three-dimensional porous Ti3AlC2 phase and glassy carbon (Ti3AlC2@C) composite in the three-dimensional porous Ti3AlC2 phase; the pore structure in the three-dimensional porous Ti3AlC2 phase is macroscopically ordered and microscopically disordered; the macroscopically ordered pore structure is a three-dimensional through-hole structure.

[0079] Among them, the compressive strength of the three-dimensional porous self-supporting electrode substrate, the area ratio of the total planar area of ​​the macroscopically ordered pore structure to the area of ​​the same plane of the three-dimensional porous Ti3AlC2, the porosity of the macroscopically ordered pore structure, and the deflection angle of the radial distribution in the through-hole structure are shown in Table 1.

[0080] The method for preparing the three-dimensional porous self-supporting electrode substrate is as follows:

[0081] (1) First, select PLA filament and use FDM method to print an ordered porous organic template (pore size is 2mm, pore rib thickness is 0.3mm). During the printing process, the parameters are set as follows: layer thickness is 0.15mm, scanning speed is 50mm / s, flow rate is 80%, heated bed temperature is 50℃, and nozzle temperature is 205℃.

[0082] After soaking the 3D printing template in a 1M NaOH solution for 48 hours, it was taken out and ultrasonically cleaned with deionized water until the pH=7. Then, the cleaned template was placed in a drying oven at 70℃ and dried for 5 hours.

[0083] (2) Take 100g of Ti3AlC2 powder and slowly add it to an ethanol solution containing phenolic resin. After stirring for 30min, add CMC and PEG in sequence and stir for 30min to obtain a uniform Ti3AlC2 slurry (in the slurry, which is not composed of Ti3AlC2 powder, polyvinyl alcohol is 50wt%, CMC and PEG are 0.5wt%, and the rest is ethanol), and store it for later use.

[0084] (3) After soaking the prepared 3D printing template in the slurry containing Ti3AlC2 for 1 min, take it out immediately and place it in a centrifuge at 286 / min to remove excess slurry. After centrifugation, take it out and air dry at room temperature, then put it in an oven at 100℃ for 1 h. Repeat the soaking 20 times to obtain a three-dimensional ordered porous Ti3AlC2 green body containing the template.

[0085] (4) The green sample was placed in a tube furnace and degreased at 800℃ for 15h under an argon atmosphere with a heating rate of 1℃ / min. Finally, it was taken out to obtain a three-dimensional ordered porous Ti3AlC2@C conductive substrate with high porosity.

[0086] Example 3

[0087] This embodiment provides a three-dimensional porous self-supporting electrode substrate, which includes a three-dimensional porous Ti3AlC2 phase and glassy carbon (Ti3AlC2@C) composite in the three-dimensional porous Ti3AlC2 phase; the pore structure in the three-dimensional porous Ti3AlC2 phase is macroscopically ordered and microscopically disordered; the macroscopically ordered pore structure is a through-hole structure.

[0088] Among them, the compressive strength of the three-dimensional porous self-supporting electrode substrate, the area ratio of the total planar area of ​​the macroscopically ordered pore structure to the area of ​​the same plane of the three-dimensional porous Ti3AlC2, the porosity of the macroscopically ordered pore structure, and the deflection angle of the radial distribution in the through-hole structure are shown in Table 1.

[0089] The method for preparing the three-dimensional porous self-supporting electrode substrate is as follows:

[0090] (1) First, select PLA filament and use FDM method to print an ordered porous organic template (pore size is 0.6mm, pore rib thickness is 0.3mm). During the printing process, the parameters are set as follows: layer thickness is 0.1mm, scanning speed is 90mm / s, flow rate is 90%, heated bed temperature is 50℃, and nozzle temperature is 205℃.

[0091] After soaking the 3D printing template in a 1M NaOH solution for 48 hours, it was taken out and ultrasonically cleaned with deionized water until the pH=7. Then, the cleaned template was placed in a drying oven at 70℃ and dried for 5 hours.

[0092] (2) Take 100g of Ti3AlC2 powder and slowly add it to an ethanol solution containing phenolic resin. After stirring for 30min, add CMC and PEG in sequence and stir for 30min to obtain a uniform Ti3AlC2 slurry (in the slurry, which is not composed of Ti3AlC2 powder, polyvinyl alcohol is 35wt%, CMC and PEG are 0.5wt% each, and the rest is ethanol), and store it for later use;

[0093] (3) After soaking the prepared 3D printing template in the slurry containing Ti3AlC2 for 1 min, take it out immediately and place it in a centrifuge at 286 / min to remove excess slurry. After centrifugation, take it out and air dry at room temperature, then put it in an oven at 100℃ for 1 h. Repeat the soaking 15 times to obtain a three-dimensional ordered porous Ti3AlC2 green body containing the template.

[0094] (4) The green sample was placed in a tube furnace and degreased at 800℃ for 15h under an argon atmosphere with a heating rate of 1℃ / min. Finally, it was taken out to obtain a three-dimensional ordered porous Ti3AlC2@C conductive substrate with high porosity.

[0095] Example 4

[0096] The difference between this embodiment and Embodiment 1 is that the radial deflection angle of the through-hole structure in this embodiment is 45˚.

[0097] The remaining preparation methods and parameters are consistent with those in Example 1.

[0098] Comparative Example 1

[0099] The difference between this comparative example and Example 1 is that the template in this comparative example is a foam template, which resulted in a disordered macroscopic porous structure.

[0100] In the preparation method, the foam template is directly replaced with a 3D printing template.

[0101] The remaining preparation methods and parameters are consistent with those in Example 1.

[0102] Comparative Example 2

[0103] The difference between this comparative example and Example 1 is that the substrate in this comparative example does not contain glassy carbon. In the degreasing reaction, the degreasing is controlled to be carried out in air at 300°C for 15 hours, and the template is directly removed, resulting in a pure Ti3AlC2 conductive substrate.

[0104] The remaining preparation methods and parameters are consistent with those in Example 1.

[0105] Figure 4 The diagram shows a comparison of the compressive strength of the three-dimensional porous self-supporting electrodes provided in Example 1 and Comparative Example 2. Figure 4 As can be seen, compared with the porous Ti3AlC2 sample without glassy carbon (Comparative Example 2), the porous Ti3AlC2 sample with glassy carbon (Example 1) has higher compressive strength while maintaining the same porosity. When the porosity is 75%, the porous Ti3AlC2 / C ceramic is 10 times stronger than the porous Ti3AlC2 ceramic without glassy carbon. When the porosity is increased to 90%, the Ti3AlC2 / C porous ceramic is 17 times stronger than the porous Ti3AlC2 ceramic without glassy carbon, indicating that the compressive strength of the electrode structure provided by the present invention has been significantly improved.

[0106] Comparative Example 3

[0107] The substrate used in this comparative example is a commercially available carbon support.

[0108] Table 1

[0109]

[0110] Mix 10 ml of ethanol and 10 ml of polyethylene glycol, stir for 10 min, add 0.02 mol / L chloroplatinic acid, continue stirring for 30 min, and slowly add NaOH to adjust the pH of the solution to 10 to obtain solution A. Then, place solution A together with the substrates of Examples 1-4 and Comparative Examples 1-3 into different hydrothermal reactors, and finally hydrothermally heat at 180℃ for 4 h. After cleaning and drying, a catalytic electrode structure with Pt metal on the surface is obtained.

[0111] The catalytic electrode structures provided in Examples 1-4 and Comparative Examples 1-3 were subjected to IT testing. After 100 hours of testing, the decay of their current density was obtained. The specific data results are shown in Table 2.

[0112] Table 2

[0113]

[0114] The data results from Examples 1 and 4 show that the radial deflection angle of the through-hole structure is too large, which leads to a decrease in its mechanical strength.

[0115] The data results from Example 1 and Comparative Example 1 show that the combination of non-3D printing templates and template methods cannot obtain a high-strength substrate with an ordered pore structure and dense internal pores. At the same time, after the foam is pyrolyzed, the hollow pores inside the pores show a glassy carbon interconnection network, which leads to a decrease in charge transport efficiency.

[0116] The data from Example 1 and Comparative Example 2 show that a glassy carbon structure cannot be synthesized in the substrate, making it impossible to achieve high stability in an acidic environment.

[0117] The data from Example 1 and Comparative Example 3 show that the catalytic electrode structure provided by the present invention has a significant stability advantage compared to conventional platinum-carbon catalytic electrodes.

[0118] In summary, by combining 3D printing technology with the template method, a hierarchical porous structure with both macroscopic and microscopic pores, and with ordered and controllable macroscopic pores, was obtained. Furthermore, after the degreasing reaction, the template was pyrolyzed in an anaerobic environment, introducing a multiphase reinforcing phase, glassy carbon, in situ. Glassy carbon possesses excellent electrical conductivity and chemical stability, enhancing both the mechanical properties and chemical stability in acidic solutions without affecting the conductivity of the MAX porous structure. This resulted in a substrate with high cross-linking and connectivity, high compressive strength, and a more stable structure. Loading catalytic particles allows space for volume contraction or expansion during electrode charging and discharging, making the reaction more stable and exhibiting excellent catalytic performance in water electrolysis for hydrogen production.

[0119] 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 three-dimensional porous self-supporting electrode substrate, characterized in that, The three-dimensional porous self-supporting electrode substrate includes a three-dimensional porous MAX phase and glassy carbon introduced in situ and composited inside the three-dimensional porous MAX phase; The pore structure in the three-dimensional porous MAX phase is macroscopically ordered and microscopically disordered. The macroscopically ordered pore structure is a through-hole structure; The radially distributed deflection angle in the through-hole structure is 0~30˚; The MAX material in the three-dimensional porous MAX phase is Ti3AlC2.

2. The three-dimensional porous self-supporting electrode substrate according to claim 1, characterized in that, The total planar area of ​​the macroscopically ordered porous structure is 45-80% of the area of ​​the same plane of the three-dimensional porous MAX phase.

3. The three-dimensional porous self-supporting electrode substrate according to claim 1, characterized in that, The porosity of the macroscopically ordered pore structure is 75-90%.

4. The three-dimensional porous self-supporting electrode substrate according to claim 1 or 2, characterized in that, The compressive strength of the three-dimensional porous self-supporting electrode substrate is 1.72±0.47~7.02±0.13MPa.

5. A method for preparing a three-dimensional porous self-supporting electrode substrate as described in any one of claims 1-4, characterized in that, The preparation method includes the following steps: MAX phase ceramic powder, binder and solvent are mixed to obtain a mixed slurry. The 3D printing template is immersed in the mixed slurry and debinding reaction is carried out to obtain the three-dimensional porous self-supporting electrode substrate.

6. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 5, characterized in that, The particle size of the MAX phase ceramic powder is 1~10μm.

7. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 5, characterized in that, Based on a total weight of 100 wt% of the non-MAX phase ceramic powder in the mixed slurry, the binder accounts for 25-50 wt% of the weight.

8. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 5, characterized in that, Based on a total weight of 100 wt% of the non-MAX phase ceramic powder in the mixed slurry, the solvent accounts for 49-74 wt% of the total weight.

9. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 5, characterized in that, The adhesive includes phenolic resin.

10. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 5, characterized in that, The solvent includes ethanol.

11. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 5, characterized in that, The mixed slurry also includes a dispersant.

12. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 11, characterized in that, The dispersant includes carboxymethyl cellulose and / or polyethylene glycol.

13. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 5, characterized in that, The method for preparing the 3D printing template includes: The template substrate is printed using the FDM-3D printing method to obtain a 3D printed template.

14. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 13, characterized in that, The template substrate includes engineering plastics and / or polylactic acid.

15. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 13, characterized in that, The scanning speed during the printing process is 10~150mm / s.

16. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 13, characterized in that, The flow rate during the printing process is 80-100%.

17. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 13, characterized in that, The layer thickness during the printing process is set to 0.05~0.35mm.

18. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 13, characterized in that, The size of the holes in the 3D printed template is 0.6~2 mm.

19. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 13, characterized in that, The diameter of the ribs in the 3D printed template is 0.3~0.6 mm.

20. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 5, characterized in that, The number of immersions is 10 to 25.

21. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 5, characterized in that, After each soaking, the sample is dried.

22. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 5, characterized in that, The degreasing reaction is carried out at a temperature of 650~850℃.

23. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 5, characterized in that, The defatting reaction is carried out under a protective atmosphere.

24. The method for preparing a three-dimensional porous self-supporting electrode substrate according to claim 5, characterized in that, The preparation method includes the following steps: The template substrate is printed using the FDM-3D printing method at a scanning speed of 10~150mm / s and a flow rate of 80~100%. The layer thickness during the printing process is set to 0.05~0.35mm, resulting in a 3D printed template with hole size of 0.6~2mm and rib thickness of 0.3~0.6mm. MAX phase ceramic powder, binder and solvent are mixed to obtain a mixed slurry. The 3D printing template is immersed in the mixed slurry 10 to 25 times. After each immersion, it is dried and degreased under a protective atmosphere to obtain the three-dimensional porous self-supporting electrode substrate.

25. A three-dimensional porous self-supporting electrode, characterized in that, The three-dimensional porous self-supporting electrode includes a three-dimensional porous self-supporting electrode substrate as described in any one of claims 1-4 and catalytic particles loaded on the three-dimensional porous self-supporting electrode substrate.

26. A method for preparing a three-dimensional porous self-supporting electrode as described in claim 25, characterized in that, The preparation method includes the following steps: The three-dimensional porous self-supporting electrode substrate, metal salt solution, and reducing agent solution are mixed and subjected to a hydrothermal reaction to obtain the three-dimensional porous self-supporting electrode.

27. The method for preparing a three-dimensional porous self-supporting electrode according to claim 26, characterized in that, The metal salts include precious metal salts.

28. The method for preparing a three-dimensional porous self-supporting electrode according to claim 26, characterized in that, The molar concentration of the metal salt solution is 0.01~0.02 mol / L.

29. The method for preparing a three-dimensional porous self-supporting electrode according to claim 26, characterized in that, The pH value of the mixed solution is 8-13.

30. The method for preparing a three-dimensional porous self-supporting electrode according to claim 26, characterized in that, The temperature of the hydrothermal reaction is 150~220℃.

31. The method for preparing a three-dimensional porous self-supporting electrode according to claim 26, characterized in that, The hydrothermal reaction takes 3 to 5 hours.

32. The use of a three-dimensional porous self-supporting electrode as described in claim 25, characterized in that, The applications include using the three-dimensional porous self-supporting electrode for hydrogen production via water electrolysis.

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