Cathode material with micro-nano hierarchical pore structure, preparation method and application

Abstract

The invention discloses a cathode material with a micro-nano hierarchical pore structure, a preparation method and application. The cathode material with the micro-nano hierarchical pore structure is applied to a hydrogen evolution reaction for catalyzing hydrogen production by alkaline electrolysis of water, and can comprise a transition metal substrate and an alloy active layer which is formed on the transition metal substrate and comprises a submicron pore structure and a nano pore structure. The cathode material with the micro-nano hierarchical pore structure has higher catalytic activity, and the hydrogen evolution reaction efficiency of hydrogen production through water electrolysis can be remarkably improved.

Description

Technical Field

[0001] The present invention relates to a cathode material with a micro-nano hierarchical pore structure, a preparation method and an application thereof. Background Art

[0002] As an important means of green hydrogen production, electrocatalytic water splitting technology shows great potential in alleviating the energy crisis and reducing environmental pollution. Although noble metal-based catalysts exhibit excellent hydrogen evolution reaction (HER) activity, their scarcity and high cost hinder large-scale applications. In recent years, non-noble metal-based catalysts (such as transition metal oxides, sulfides, phosphides and alloys) have become a research hotspot. However, the existing technologies for preparing hydrogen evolution reaction catalysts either rely on noble metal precursors, which are costly and difficult to produce on a large scale, or are based on cheap metals such as nickel and iron, and these catalysts often face problems such as a single active site and mass transfer limitation caused by a single pore structure. Therefore, it is very important to develop highly catalytically active catalytic materials for the hydrogen evolution reaction in electrolytic water hydrogen production. Summary of the Invention

[0003] In view of this, the present invention provides a cathode material with a micro-nano hierarchical pore structure, a preparation method and an application thereof. The cathode material with a micro-nano hierarchical pore structure has a stable structure and a richer specific surface area, and has high mass transfer performance and higher catalytic activity, and can significantly improve the hydrogen evolution reaction efficiency of electrolytic water hydrogen production.

[0004] To solve the above technical problems, the present invention provides the following technical solutions:

[0005] In a first aspect, the present invention provides a cathode material with a micro-nano hierarchical pore structure, which is applied to catalyze the hydrogen evolution reaction in alkaline electrolytic water hydrogen production. The cathode material includes: a transition metal substrate, and an alloy active layer formed on the transition metal substrate, the alloy active layer including a micron-scale pore structure and / or a sub-micron-scale pore structure and a nano-scale pore structure.

[0006] In a second aspect, an embodiment of the present invention provides a preparation method of a cathode material with a micro-nano hierarchical pore structure, including:

[0007] Step 1: Completely cover the surface of the transition metal substrate with metal powder; under the protection of an inert gas, anneal the transition metal substrate covered with the metal powder to form a primary alloy layer on the transition metal substrate;

[0008] Step 2: Through vapor dealloying treatment, form a micron-scale pore structure and / or a sub-micron-scale pore structure on the primary alloy layer;

[0009] Step 3: Through liquid-phase dealloying treatment, a nano-scale pore structure is further formed on the primary alloy layer with the micron-scale pore structure and / or submicron-scale pore structure, obtaining an alloy active layer containing the micron-scale pore structure and / or submicron-scale pore structure and the nano-scale pore structure.

[0010] Optionally, Step 1 includes: adopting a two-step alloying treatment to form a primary alloy layer on the transition metal substrate.

[0011] Optionally, Step 1 includes:

[0012] Step 11: Completely cover the surface of the transition metal substrate with the metal powder of the second metal; after 15 min to 30 min in an inert gas environment, anneal the transition metal substrate covered with the metal powder of the second metal at an annealing temperature of 300 °C to 1000 °C for 0.1 h to 5 h to obtain an intermediate product;

[0013] Step 12: Clean the intermediate product;

[0014] Step 13: Completely cover the surface of the intermediate product with the metal powder of the third metal; under the protection of an inert gas, anneal the intermediate product covered with the metal powder of the third metal at an annealing temperature of 300 °C to 1000 °C and an annealing time of 0.1 h to 5 h to form a primary alloy layer.

[0015] In a third aspect, an embodiment of the present invention provides an application of the cathode material with a micro-nano multi-level pore structure provided in the first aspect of the above embodiments. The cathode material with a micro-nano multi-level pore structure is applied to the hydrogen evolution reaction of catalytic electrolysis of water to produce hydrogen. The application further includes:

[0016] Using the cathode material with a micro-nano multi-level pore structure as the cathode for catalytic electrolysis of water to produce hydrogen, and applying a negative electrode potential to the cathode.

[0017] The technical solution of the first aspect of the above invention has the following advantages or beneficial effects:

[0018] The cathode material with a micro-nano multi-level pore structure provided by the embodiment of the present invention, through the cooperation of the micron-scale pore structure and / or submicron-scale pore structure and the nano-scale pore structure, can make the alloy active layer have a richer specific surface area and can expose more catalytic active sites on the alloy active layer. Further, the cooperation of the micron-scale pore structure and / or submicron-scale pore structure and the nano-scale pore structure can improve the mass transfer efficiency while improving the specific surface area and catalytic active sites, and significantly improve the catalytic activity for the hydrogen evolution reaction of electrolysis of water to produce hydrogen.

[0019] Furthermore, the transition metal substrate cooperates with the alloy active layer, enabling the cathode material with a micro-nano hierarchical pore structure to have better mechanical strength and self-supporting performance, reducing the risk of structural collapse, thereby ensuring the structural stability and reliability of the cathode material with a micro-nano hierarchical pore structure and enhancing its recycling utilization rate. Brief Description of the Drawings

[0020] Figure 1 is a scanning electron microscope image of the cathode material with a micro-nano hierarchical pore structure prepared according to Example 1 at a scale of 5 μm;

[0021] Figure 2 is a scanning electron microscope image of the cathode material with a micro-nano hierarchical pore structure prepared according to Example 1 at a scale of 500 nm;

[0022] Figure 3 is a schematic diagram of the main process of the preparation method of the cathode material with a micro-nano hierarchical pore structure according to an embodiment of the present invention;

[0023] Figure 4 is a graph showing the catalytic performance test of the cathode material with a micro-nano hierarchical pore structure prepared in Example 1, the nickel mesh substrate, and commercial Raney nickel.

[0024] The reference numerals are as follows:

[0025] 20 - alloy active layer; 21 - ligament; 22 - submicron pore structure; 23 - nano pore structure. Detailed Description of the Embodiments

[0026] Although there are currently some designs of porous structure catalysts for the hydrogen evolution reaction in electrolytic water hydrogen production, there are still significant limitations in the existing porous structure catalysts, whether in terms of structure, preparation process, or catalytic performance optimization. For example, although nanoporous metals (such as porous gold, porous silver, etc.) prepared by traditional noble metal dealloying methods have high activity, they rely on noble metal precursors. On the one hand, the cost of noble metal precursors is high and it is difficult to scale up production; on the other hand, the catalytic materials prepared using noble metal precursors are generally in the shape of cylinders or strips, which are quite different from the actual cathode electrodes. They often need to be loaded on the substrate with the help of adhesives, which not only covers some catalytic active sites, but also has a relatively high interfacial contact resistance between the catalytic material and the substrate, reducing conductivity and limiting the catalytic performance of the catalytic material. Moreover, the bonding method is prone to causing the catalytic material to fall off, resulting in the loss of the catalytic material and also affecting the catalytic performance of the catalytic material. In addition, the currently used template method or electrochemical deposition method has cumbersome steps and mainly focuses on the optimization of single-scale pore channels. It is difficult to precisely control the hierarchical pore structure and lacks a systematic design of the synergistic effect of the hierarchical pore channels. It is easy to cause hydrogen-producing bubbles to accumulate around the cathode, shielding the catalytic active sites of the catalytic material and leading to easy activity decay of the catalyst due to poor mass transfer at high current densities.

[0027] In order to solve the above problems existing in the prior art, an embodiment of the present invention provides a cathode material with a micro-nano hierarchical pore structure, a preparation method, and an application, which have a novel structure.

[0028] It should be noted that the micro-nano hierarchical pore structure involved in the embodiment of the present invention means that the cathode material contains micron-sized pore structures or sub-micron-sized pore structures (such as pore structures with micron-sized dimensions or sub-micron-sized dimensions) and nano-sized pore structures (such as pore structures with nano-sized dimensions). The micron-sized pore structure or sub-micron-sized pore structure cooperates with the nano-sized pore structure, enabling the cathode material to have a more stable structure, a rich surface morphology, a larger surface area, and can expose more catalytic active sites.

[0029] Among them, the diameter of the micron-sized pore structure is generally larger than that of the sub-micron-sized pore structure.

[0030] Among them, the sub-micron-sized pore structure means that if the diameters of these pores are expressed in nanometers, the numerical values of the diameters of these pores will be relatively large (generally exceeding 500 nm), and if the diameters of these pores are expressed in microns, the numerical values of the diameters of these pores will be relatively small (generally less than 2 μm). That is to say, the pore diameter of the sub-micron-sized pore structure is generally between the micron level and the nano level.

[0031] Among them, Figure 1It is a scanning electron microscope image at a scale of 5 μm of the cathode material with a micro-nano hierarchical pore structure prepared according to Example 1; Figure 2 It is a scanning electron microscope image at a scale of 500 nm of the cathode material with a micro-nano hierarchical pore structure prepared according to Example 1.

[0032] Specifically, an embodiment of the present invention provides a cathode material with a micro-nano hierarchical pore structure. The cathode material with a micro-nano hierarchical pore structure is applied to the hydrogen evolution reaction for catalytic alkaline water electrolysis to produce hydrogen. More specifically, as Figure 1 and Figure 2 shown, the cathode material with a micro-nano hierarchical pore structure may include: a transition metal substrate, and an alloy active layer 20 formed on the transition metal substrate and including a micron-scale pore structure and / or a submicron-scale pore structure 22 and a nano-scale pore structure 23.

[0033] It can be understood that the micron-scale pore structure and / or the submicron-scale pore structure 22 means that the micron-scale pore structure and the submicron-scale pore structure 22 may exist simultaneously in the cathode material or only one of them may exist. In the following various embodiments and descriptions, in order to clearly illustrate the relationship between the micron-scale pore structure and the submicron-scale pore structure 22 and the nano-scale pore structure 23, the following embodiments mainly take the submicron-scale pore structure 22 as an example for illustration. All or part of the submicron-scale pore structure 22 can be replaced by the micron-scale pore structure. That is to say, the submicron-scale pore structure 22 in the following various embodiments can be replaced by the micron-scale pore structure or a mixed structure of the micron-scale pore structure and the submicron-scale pore structure 22. In addition, those skilled in the art can obtain a micron-scale pore structure or a mixed structure of the submicron-scale pore structure 22 and the micron-scale pore structure by adjusting process parameters based on the preparation method of the submicron-scale pore structure 22.

[0034] Among them, in addition to serving as a carrier for the alloy active layer 20, the transition metal substrate also provides transition metals for the alloy active layer 20, that is, the alloy active layer 20 contains transition metals derived from the transition metal substrate. This structure can make the combination of the alloy active layer 20 and the transition metal substrate more stable and reliable, and this structure can eliminate the interfacial contact resistance between the alloy active layer 20 and the transition metal substrate, which helps to reduce the catalytic energy consumption.

[0035] Among them, the alloy active layer 20 is the core of the catalytic active sites, which generally includes an alloy formed by at least two metals. As described above, some of the metals in the alloy are derived from the transition metals in the transition metal substrate. Preferably, the alloy active layer 20 can also be a multi-layer structure with phase stacking, that is, the alloy active layer 20 is formed layer by layer, which makes the alloy active layer 20 have a richer surface and a larger surface area. This phase-stacked multi-layer structure also makes the micron-scale pore structure and / or sub-micron-scale pore structure 22 and the nano-scale pore structure 23 more diverse on the alloy active layer 20, which is conducive to carrying and exposing more catalytic active sites, and is conducive to its contact with the electrolyte and bubble diffusion. In addition, the micron-scale pore structure and / or sub-micron-scale pore structure 22 included in the alloy active layer 20 communicate with each other, and the ligaments 21 communicate with each other, which is conducive to the discharge and diffusion of bubbles during the hydrogen evolution reaction, and improves the mass transfer efficiency and bubble diffusion efficiency of the cathode material.

[0036] Among them, the existence of the nano-scale pore structure 23 makes the alloy active layer 20 form a surface with a richer structure and a larger surface area, which is more conducive to exposing catalytic active sites, increasing the contact area between the alloy active layer 20 and the electrolyte, and promoting the catalytic reaction.

[0037] Therefore, the cathode material with a micro-nano multi-level pore structure provided by the embodiments of the present invention can make the alloy active layer have a richer specific surface area and expose more catalytic active sites through the cooperation of the micron-scale pore structure and / or sub-micron-scale pore structure and the nano-scale pore structure. Further, the cooperation of the micron-scale pore structure and / or sub-micron-scale pore structure and the nano-scale pore structure can improve the specific surface area and catalytic active sites, and at the same time can also improve the mass transfer efficiency, and significantly improve the catalytic activity of the hydrogen evolution reaction for electrolytic water hydrogen production.

[0038] Further, the cooperation of the transition metal substrate and the alloy active layer makes the cathode material with a micro-nano multi-level pore structure have better mechanical strength and better self-supporting performance, which can reduce the risk of structural collapse, thereby ensuring the structural stability and structural reliability of the cathode material with a micro-nano multi-level pore structure, and improving its recycling rate.

[0039] In addition, the cooperation of the micron-scale pore structure and / or sub-micron-scale pore structure and the nano-scale pore structure as a catalytic center provides a richer source of active sites.

[0040] In addition, for the cathode material with a micro-nano hierarchical pore structure provided by the embodiments of the present invention, since the alloy itself has a certain rigidity, the alloy active layer 20 has relatively strong self-supporting performance, which can reduce the risk of collapse of the micro-scale pore structure and / or sub-micro-scale pore structure 22 and the nano-scale pore structure 23, thereby ensuring the stability of the micro-scale pore structure and / or sub-micro-scale pore structure 22 and the nano-scale pore structure 23, and further ensuring the catalytic stability and catalytic activity of the cathode material with a micro-nano hierarchical pore structure.

[0041] In addition, the micro-scale pore structure and / or sub-micro-scale pore structure 22 and the nano-scale pore structure 23 of the alloy active layer 20 can be evenly dispersed, ensuring the balance of catalytic reactions at each position, further optimizing the mass transfer efficiency and gas diffusion rate of the catalytic process, and enabling the cathode material with a micro-nano hierarchical pore structure to have high activity and long-term stability at high current densities.

[0042] Next, the transition metal substrate and the alloy active layer 20 included in the cathode material with a micro-nano hierarchical pore structure will be described separately.

[0043] Specifically, the transition metal substrate is a foamed substrate or a reticulated substrate. The transition metal substrate generally includes one of the following transition metals or a metal alloy formed by at least two of the following transition metals: nickel, iron, cobalt, and copper. Preferably, the transition metal substrate is a reticulated structure or a foamed structure formed by one of nickel, iron, cobalt, and copper, or the transition metal substrate is a reticulated structure or a foamed structure formed by an alloy containing at least two of nickel, iron, cobalt, and copper. By selecting a reticulated structure or a foamed structure formed by a transition metal or an alloy containing a transition metal as the transition metal substrate, on the one hand, it has relatively strong self-supporting performance, enabling the cathode material with a micro-nano hierarchical pore structure to have strong self-supporting performance and not easily collapse; on the other hand, the reticulated structure or foamed structure of the transition metal substrate can form a relatively strong bond with the alloy active layer 20, ensuring the stability and reliability of the micro-scale pore structure and / or sub-micro-scale pore structure 22 and the nano-scale pore structure 23. In addition, the cathode material with a micro-nano hierarchical pore structure formed based on the reticulated structure or foamed structure of the transition metal substrate can be directly used as the cathode for hydrogen production by electrolyzing water without loading the cathode material with a micro-nano hierarchical pore structure on other substrates, improving the reliability and stability of the cathode for hydrogen production by electrolyzing water and eliminating the interfacial contact resistance.

[0044] More preferably, the above-mentioned transition metal substrate is generally a nickel mesh structure. Through research, it is found that compared with the mesh structure and foam structure of other transition metals, the nickel mesh structure can provide more stable self-support, and after the cathode material is used for a long time, it can still ensure the structural stability of the micro-scale pore structure and / or sub-micro-scale pore structure 22 and nano-scale pore structure 23, and it is not easy to collapse. In addition, the nickel mesh structure has a low cost, and it is easier to control the cost of the cathode material with a micro-nano multi-level pore structure.

[0045] More preferably, in the case where the transition metal substrate is an alloy formed by a plurality of transition metals (that is, the transition metal substrate contains two or more transition metals), the masses of the plurality of transition metals in the alloy are generally the same. Exemplarily, for the substrate of nickel-iron alloy, the mass ratio of nickel and iron contained therein is 1:1, so that the structure of each region of the transition metal substrate is relatively uniform, thereby ensuring the uniformity of the distribution of the alloy active layer 20 containing the micro-scale pore structure and / or sub-micro-scale pore structure 22 and nano-scale pore structure 23 formed based on the transition metal substrate.

[0046] Among them, for the transition metal substrate with a foam structure or a mesh structure, its mesh number (that is, the number of pores contained in a unit area) is generally 30 to 50 meshes. In addition, those skilled in the art can also select according to actual needs. Generally speaking, the larger the mesh number of the transition metal substrate, the smaller the size of the pores contained in the unit area of the transition metal substrate, the larger the surface area, which is beneficial to increasing the loading of the alloy active layer 20 containing the micro-scale pore structure and / or sub-micro-scale pore structure 22 and nano-scale pore structure 23. However, when the mesh number increases, the cost of the transition metal substrate will also increase. And the smaller the mesh number of the transition metal substrate, the larger the size of the pores contained in the unit area, the smaller the surface area, which is not conducive to the loading of the alloy active layer 20 containing the micro-scale pore structure and / or sub-micro-scale pore structure 22 and nano-scale pore structure 23. However, the smaller the mesh number, the lower the cost of the transition metal substrate.

[0047] Furthermore, for the alloy active layer 20, it further includes: ligaments 21. More specifically, the sub-micro-scale pore structure 22 is surrounded by the ligaments 21; the nano-scale pore structure 23 is formed on the ligaments 21. Among them, the existence of the micro-scale pore structure and / or sub-micro-scale pore structure 22 is beneficial to exposing catalytic active sites and increasing the contact area between the cathode material and the electrolyte. The existence of the micro-scale pore structure and / or sub-micro-scale pore structure 22 is also beneficial to electrolyte mass transfer and bubble diffusion. And the nano-scale pore structure 23 can further enrich the surface morphology, expose more catalytic active sites, and further increase the contact area between the cathode material and the electrolyte.

[0048] Among them, the alloy active layer 20 generally includes: the same transition metal as the transition metal substrate, zinc, and at least one of the following first metals: First metals: aluminum, manganese, and molybdenum. That is to say, the alloy in the alloy active layer 20, in addition to containing the same transition metal as the transition metal substrate, also includes zinc, which can ensure the bonding strength between the alloy active layer 20 and the transition metal substrate, make the alloy active layer 20 not easy to fall off, and ensure the reliability of the cathode material with a micro-nano multi-level pore structure. Preferably, the transition metal in the alloy active layer 20 that is the same as the transition metal substrate is derived from the transition metal substrate to further enhance the bonding strength between the alloy active layer 20 and the transition metal substrate.

[0049] Furthermore, by introducing zinc into the alloy active layer 20, the formation of the micron-sized pore structure and / or submicron-sized pore structure 22 can be ensured, and the dispersion uniformity and size controllability of the micron-sized pore structure and / or submicron-sized pore structure 22 can be guaranteed. Furthermore, at least one of aluminum, manganese, and molybdenum can ensure the formation of the nano-sized pore structure 23 in the alloy active layer 20 and can guarantee the support strength of the alloy active layer 20.

[0050] Furthermore, for the alloy active layer 20, its thickness is generally 3 μm to 40 μm. Exemplarily, the thickness of the alloy active layer 20 can be 3 μm, 5 μm, 8 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, or 40 μm, etc. By controlling the thickness of the alloy active layer 20, the strong support of the alloy active layer 20 can be ensured, and at the same time, the strength of the ligaments 21 formed by the dealloying treatment method, and the diameters of the submicron-sized pore structure 22 and the nano-sized pore structure 23 can be guaranteed.

[0051] Even further, as Figure 1 shown, for the cathode material containing the submicron-sized pore structure 22, the diameter D of the submicron-sized pore structure 22 is generally greater than or equal to 0.7 μm and less than or equal to 1.0 μm. Exemplarily, the diameter D of the submicron-sized pore structure 22 can be 0.7 μm, 0.8 μm, 0.9 μm, or 1.0 μm, etc.

[0052] In addition, for the cathode material containing the micron-sized pore structure, the diameter of the micron-sized pore structure is generally greater than 1.0 μm and less than or equal to 5.0 μm. Exemplarily, the diameter of the micron-sized pore structure can be 1.0 μm, 2 μm, 3 μm, or 5.0 μm, etc. By regulating the diameter of the submicron-sized pore structure 22 and / or the diameter of the micron-sized pore structure, the bubble discharge efficiency can be effectively guaranteed, thereby ensuring the contact between the cathode material and the electrolyte.

[0053] In addition, the diameter of the nanoscale pore structure 23 is generally 10 nm to 20 nm. Exemplarily, the diameter of the submicron-scale pore structure 22 can be 10 nm, 12 nm, 14 nm, 15 nm, 16 nm, 18 nm, 20 nm, etc. By controlling the diameter of the nanoscale pore structure 23, the alloy layer 20 can have a richer surface and carry more layered active layers 30, so as to increase the loading amount of catalytic active sites.

[0054] Furthermore, the micron-scale pore structure and / or the submicron-scale pore structure 22 are generally in a double-connected state. This double-connected state generally means that the pore structures included in the alloy active layer 20 are connected to each other and the ligaments 21 included in the alloy active layer 20 are connected to each other. Specifically, for the structure of the alloy active layer 20 including a micron-scale pore structure and ligaments 21, the micron-scale pore structures are connected to each other, and the ligaments are connected to each other; for the structure of the alloy active layer 20 including a submicron-scale pore structure 22 and ligaments 21, the submicron-scale pore structures 22 are connected to each other, and the ligaments are connected to each other; for the structure of the alloy active layer 20 including a micron-scale pore structure, a submicron-scale pore structure 22, and ligaments 21, the micron-scale pore structures, the submicron-scale pore structures 22, and between the micron-scale pore structure and the submicron-scale pore structure 22 are connected to each other, and the ligaments are connected to each other. Through the structure in which the pore structures are connected to each other and the ligaments 21 are connected to each other, the bubbles generated by the hydrogen evolution reaction can be discharged conveniently, and the mass transfer rate and the bubble diffusion and discharge efficiency can be improved.

[0055] Based on the above-mentioned embodiments, for the cathode material with a micro-nano multi-level pore structure provided by the embodiments of the present invention, its catalytic core is the alloy active layer 20. The core structure of the alloy active layer 20 is the ligaments 21, the micron-scale pore structure and / or the submicron-scale pore structure 22 surrounded by the ligaments 21, and the nanoscale pore structure 23 formed on the ligaments. Among them, the ligaments 21 provide most of the catalytic active sites, the submicron-scale pore structure 22 can accelerate the penetration of the electrolyte and the diffusion and discharge of bubbles, so as to ensure the mass transfer efficiency and gas diffusion rate during the hydrogen evolution reaction under high current, and the nanoscale pore structure 23 can provide a richer surface to expose more catalytic active sites and reduce the energy barrier of the hydrogen evolution reaction kinetics, thereby reducing the overpotential of the hydrogen evolution reaction.

[0056] Furthermore, the embodiments of the present invention also provide a preparation method for a cathode material with a micro-nano multi-level pore structure. As Figure 3 shown, the preparation method may include the following steps:

[0057] Step S301: Completely cover the surface of the transition metal substrate with metal powder; under the protection of an inert gas, anneal the transition metal substrate covered with metal powder to form a primary alloy layer on the transition metal substrate.

[0058] Among them, for the transition metal substrate, it generally includes one of the following transition metals or a metal alloy formed by at least two of the following transition metals: nickel, iron, cobalt, and copper. Preferably, the transition metal substrate is a mesh structure or a foam structure formed by one of nickel, iron, cobalt, and copper, or the transition metal substrate is a mesh structure or a foam structure formed by an alloy containing at least two of nickel, iron, cobalt, and copper. By selecting a mesh structure or a foam structure formed by a transition metal or an alloy containing a transition metal as the transition metal substrate, on the one hand, it has relatively strong self-supporting performance, enabling the cathode material with a micro-nano multi-level pore structure to have strong self-supporting performance and not prone to collapse; on the other hand, the mesh structure or foam structure of the transition metal substrate can form a relatively strong bond with the alloy active layer 20, ensuring the stability and reliability of the micro-scale pore structure and / or sub-micro-scale pore structure 22 and the nano-scale pore structure 23. In addition, the cathode material with a micro-nano multi-level pore structure formed based on the mesh structure or foam structure of the transition metal substrate can be directly used as the cathode for electrolytic water hydrogen production without loading the cathode material with a micro-nano multi-level pore structure on other substrates, improving the reliability and stability of the cathode for electrolytic water hydrogen production and eliminating the interfacial contact resistance.

[0059] More preferably, the above-mentioned transition metal substrate is generally a nickel mesh structure. Through research, it is found that compared with the mesh structures and foam structures of other transition metals, the nickel mesh structure can provide more stable self-support, and after the long-term use of the cathode material, it can still ensure the structural stability of the micro-scale pore structure and / or sub-micro-scale pore structure 22 and the nano-scale pore structure 23 and is not prone to structural collapse. In addition, the nickel mesh structure has a low cost, and it is easier to control the cost of the cathode material with a micro-nano multi-level pore structure.

[0060] More preferably, when the transition metal substrate is formed by an alloy of multiple transition metals, the masses of the multiple transition metals in the alloy are generally the same. Exemplarily, for the substrate of a nickel-iron alloy, the mass ratio of nickel and iron it contains is 1:1, so that the structure of each region of the transition metal substrate is relatively uniform, thereby ensuring the uniformity of the distribution of the alloy active layer 20 containing the micro-scale pore structure and / or sub-micro-scale pore structure 22 and the nano-scale pore structure 23 formed based on the transition metal substrate.

[0061] Among them, for the transition metal substrate with a foam structure or a reticular structure, its mesh number (i.e., the number of pores contained per unit area) is generally 30 to 50 meshes. In addition, those skilled in the art can also select according to actual needs. Generally speaking, the larger the mesh number of the transition metal substrate, the smaller the size of the pores contained per unit area of the transition metal substrate, the larger the surface area, which is beneficial to increasing the loading of the alloy active layer 20 containing micron-scale pore structures and / or sub-micron-scale pore structures 22 and nano-scale pore structures 23. However, when the mesh number increases, the cost of the transition metal substrate will increase. And the smaller the mesh number of the transition metal substrate, the larger the size of the pores contained per unit area, the smaller the surface area, which is not conducive to the loading of the alloy active layer 20 containing sub-micron-scale pore structures 22 and nano-scale pore structures 23. However, the smaller the mesh number, the lower the cost of the transition metal substrate.

[0062] Step S302: Through vapor dealloying treatment, form micron-scale pore structures and / or sub-micron-scale pore structures on the primary alloy layer.

[0063] Step S303: Through liquid-phase dealloying treatment, further form nano-scale pore structures on the primary alloy layer formed with micron-scale pore structures and / or sub-micron-scale pore structures, to obtain the alloy active layer 20 containing micron-scale pore structures and / or sub-micron-scale pore structures 22 and nano-scale pore structures 23.

[0064] The annealing treatment, vapor dealloying treatment, and liquid-phase dealloying treatment involved in the preparation method provided by the embodiments of the present invention all have relatively wide process windows, are easy to operate and implement. Therefore, the preparation method provided by the embodiments of the present invention is convenient for industrial production.

[0065] In addition, the raw materials for each of the above steps can be recycled and reused, effectively reducing the manufacturing cost, ensuring the effective utilization of raw materials, reducing waste generation, and realizing green production.

[0066] In addition, through the above preparation method, the cathode material with a micro-nano multi-level pore structure produced can form a stable combination through the transition metal substrate and the alloy active layer 20, increasing the structural strength and structural stability of the cathode material, and being able to ensure the high catalytic activity and long-term stability of the cathode material.

[0067] Specifically, for step S301, its specific implementation scheme may include: adopting two-step alloying treatment to form a primary alloy layer on the transition metal substrate. Through the two-step alloying treatment, a basis is provided for the subsequent two-step dealloying treatment.

[0068] More specifically, the specific implementation of step S301 may include: completely covering the surface of the transition metal substrate with the metal powder of the second metal; after 15 min to 30 min in an inert gas environment, annealing the transition metal substrate covered with the metal powder of the second metal at an annealing temperature of 300 °C to 1000 °C for 0.1 h to 5 h to obtain an intermediate product; cleaning the intermediate product; completely covering the surface of the intermediate product with the metal powder of the third metal; under the protection of an inert gas, annealing the intermediate product covered with the metal powder of the third metal at an annealing temperature of 300 °C to 1000 °C and an annealing time of 0.1 h to 5 h to form a primary alloy layer. Exemplarily, the time for the transition metal substrate to be in an inert gas (such as argon) environment can be 15 min, 18 min, 20 min, 25 min or 30 min, etc. By controlling the time for the transition metal substrate to be in an inert gas (such as argon) environment, it is possible to avoid oxidation of the transition metal substrate and the primary alloy layer during the alloying process, so as to ensure the bonding strength between the primary alloy layer and the metal substrate, and ensure that the alloy active layer 20 formed later can expose more catalytic active sites, as well as the process reliability of the subsequent dealloying process and the uniformity of the micron-scale pore structure and / or sub-micron-scale pore structure 22 and nano-scale pore structure 23.

[0069] Among them, the second metal is generally one of the following metals: zinc, aluminum, manganese, and molybdenum.

[0070] The third metal is generally one of the following metals: zinc, aluminum, manganese, and molybdenum, and the second metal and the third metal are different metals.

[0071] More preferably, the second metal is selected from one of aluminum, manganese, and molybdenum, and the third metal is selected as zinc. By selecting zinc as the third metal, the uniformity of the micron-scale pore structure and / or sub-micron-scale pore structure 22 can be ensured, and the alloy active layer 20 can be ensured to reach a double-pass state.

[0072] Further, for step S302, its specific implementation may include: heating the primary alloy layer at a heating temperature of 300 °C to 850 °C for 0.5 h to 3.5 h within a pressure range of 10 -3 Pa to 10 5 Pa. Exemplarily, the pressure for the vapor-phase dealloying treatment can be 10 -3 Pa, 0.1 Pa, 1 Pa, 10 Pa, 100 Pa, 1000 Pa or 10 5 Pa, etc. The heating temperature can be 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, 800 °C or 850 °C, etc. The time for heating the primary alloy layer can be 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h or 3.5 h, etc.

[0073] Regarding step S303, the primary alloy layer formed with micron-scale pore structures and / or sub-micron-scale pore structures is placed in a chemical etching solution for chemical etching treatment to form nano-scale pore structures.

[0074] Among them, the chemical etching solution is an alkaline aqueous solution containing at least one of the following alkaline compounds: potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium phosphate, disodium hydrogen phosphate, potassium phosphate solution, potassium hydrogen phosphate, ammonium carbonate, ammonium bicarbonate, and ammonium phosphate; or the chemical etching solution is an acidic aqueous solution containing at least one of the following acidic compounds: sodium dihydrogen phosphate, potassium dihydrogen phosphate, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium hydrogen phosphate, and ammonium dihydrogen phosphate.

[0075] The molar concentration of the chemical etching solution is 0.1 M to 10 M. Exemplarily, the molar concentration of the chemical etching solution can be 0.1 M, 1 M, 3 M, 5 M, 8 M, or 10 M, etc.

[0076] The etching time of the chemical etching solution is 0.1 h to 24 h. Exemplarily, the etching time of the chemical etching solution is 0.1 h, 0.5 h, 1 h, 6 h, 8 h, 12 h, 15 h, 18 h, 20 h, 22 h, or 24 h, etc.

[0077] The etching temperature of the chemical etching solution is 10 °C to 80 °C. Exemplarily, the etching temperature of the chemical etching solution is 10 °C, 20 °C, 25 °C, 30 °C, 35 °C, 50 °C, 70 °C, or 80 °C, etc.

[0078] In summary, the preparation method provided by the embodiments of the present invention realizes the step-by-step construction of micron-scale pore structures and / or sub-micron-scale pore structures 22 and nano-scale pore structures 23 through step-by-step alloying and step-by-step dealloying, by designing the alloying components of each step of alloying and regulating the corresponding order of dealloying steps. Among them, the alloying component of the first step provides a sacrificial phase for the liquid-phase dealloying treatment, and the alloying component of the second step provides volatile components for the gas-phase dealloying treatment, realizing the construction of micron-scale pore structures and / or sub-micron-scale pore structures 22 in the gas-phase dealloying treatment. Then, through further liquid-phase dealloying treatment, on the basis of the existing sub-micron-scale pore structures 22, further etching is carried out to form nano-scale pore structures 23 at the ligaments of the micron-scale pore structures and / or sub-micron-scale pore structures 22, thereby synergistically forming a "micron-nano" or "micron-sub-micron-nano" or "sub-micron-nano" hierarchical pore channel synergistic structure with both high specific surface area and rapid mass transfer. The micron-scale pore structures and / or sub-micron-scale pore structures 22 are used for rapid mass exchange to promote the penetration of the electrolyte and accelerate the escape of gas. The nano-scale pore structures 23 on the large-size ligaments enlarge the effective surface area and provide high-density active sites, thereby improving the catalytic activity and significantly enhancing the catalytic activity of the material for the hydrogen evolution reaction (HER).

[0079] In addition, materials used in the embodiments of the present invention, such as nickel, manganese, zinc, etc. commonly used in industry, have lower costs.

[0080] Furthermore, the preparation method provided by the embodiments of the present invention can break through the size limitation of single dealloying by stepwise regulating the alloy composition and dealloying path, and achieve the precise construction of a "micrometer-nanometer" or "micrometer-submicrometer-nanometer" or "submicrometer-nanometer" hierarchical pore structure. At the same time, combined with the self-supporting characteristics of the structure and low-cost metals, the alloy active layer and the transition metal substrate of the cathode material are strongly bonded, increasing the bonding strength and structural stability.

[0081] Furthermore, the embodiments of the present invention provide an application of the cathode material with a micro-nano hierarchical pore structure for each of the above embodiments. The cathode material with a micro-nano hierarchical pore structure is applied to the hydrogen evolution reaction of catalytic electrolytic water for hydrogen production. Specifically, the application further includes: using the cathode material with a micro-nano hierarchical pore structure as the cathode for catalytic electrolytic water for hydrogen production, and applying a negative potential to the cathode.

[0082] The following uses several specific embodiments to detail the preparation process provided by the embodiments of the present invention and the cathode material with a micro-nano hierarchical pore structure prepared based on this preparation process.

[0083] Example 1

[0084] Step A1: Prepare the following raw materials: a nickel mesh substrate with a mesh size of 46 meshes; metal manganese powder with a particle size of 325 meshes; metal zinc powder with a particle size of 325 meshes.

[0085] Step B1: Place the nickel mesh substrate in a tubular furnace, and cover the surface of the nickel mesh substrate with metal manganese powder to ensure that the surface of the nickel mesh substrate is not exposed.

[0086] Step C1: Select argon as the protective gas. After continuously introducing argon into the tubular furnace for 30 minutes, heat the nickel mesh substrate covered with metal manganese powder in the tubular furnace. The annealing temperature is 1000 °C, and the holding time is 1 hour. A nickel-manganese alloy layer is formed on the surface of the nickel mesh substrate and then cooled.

[0087] Step D1: Separate the cooled nickel mesh substrate with a nickel-manganese alloy layer from the metal manganese powder and thoroughly clean the residual powder on the surface.

[0088] Step E1: Cover the surface of the nickel mesh substrate with a nickel-manganese alloy layer with metal zinc powder to ensure that the surface of the nickel mesh substrate with a nickel-manganese alloy layer is not exposed.

[0089] Step F1: Select argon as the protective gas. After continuously introducing argon into the tubular furnace for 30 minutes, heat the nickel mesh substrate with a nickel-manganese alloy layer covered with metallic zinc powder in the tubular furnace. The annealing temperature is 400 °C, and the holding time is 0.5 h. Alloy zinc in the nickel-manganese alloy layer to form a nickel-manganese-zinc alloy layer, and then cool it.

[0090] Step G1: Separate the cooled nickel mesh substrate with a nickel-manganese-zinc alloy layer from the metallic zinc powder and thoroughly clean the residual powder on the surface.

[0091] Step H1: Place the nickel mesh substrate with a nickel-manganese-zinc alloy layer into a vacuum heat treatment furnace for heat treatment. The air pressure is 50 Pa, the temperature is 650 °C, and the holding time is 1.5 h. Use the gas-phase dealloying method to form a ligament and submicron-sized pore structure on the surface of the nickel-manganese-zinc alloy layer.

[0092] Step I1: Immerse the nickel-manganese-zinc alloy layer with a submicron-sized pore structure into a chemical etching solution containing (NH4)2SO4 with a molar concentration of 6.0 M, and etch it at a water bath temperature of 55 °C for 12 h. After chemical etching, form a nano-sized pore structure on the ligament.

[0093] Step J1: Wash and dry the nickel-manganese-zinc alloy layer with submicron-sized and nano-sized pore structures. After thoroughly rinsing it with a large amount of deionized water, perform a drying treatment.

[0094] Example 2

[0095] The difference from Example 1 is that in Step A2, a nickel-iron alloy substrate with a mesh structure is selected, and a mixed metal powder of metallic aluminum powder and metallic molybdenum powder with a particle size of 325 mesh; metallic zinc powder with a particle size of 325 mesh is used; in Step C2, a mixed metal powder of metallic aluminum powder and metallic molybdenum powder is used, the annealing temperature is 800 °C, and the holding time is 3 h; in Step F2, metallic zinc powder is used, the annealing temperature is 500 °C, and the holding time is 5 h; the air pressure used for the heat treatment in Step H2 is 10 5 Pa, the temperature is 850 °C, and the holding time is 3.5 h; in Step I2, potassium dihydrogen phosphate solution is selected as the chemical etching solution, and the etching time is 8 h.

[0096] Example 3

[0097] The difference from Example 1 is that in Step A2, a cobalt substrate with a mesh structure is selected, and a mixed metal powder of metallic aluminum powder and metallic manganese powder with a particle size of 325 mesh; metallic zinc powder with a particle size of 325 mesh is used; in Step C2, a mixed metal powder of metallic aluminum powder and metallic manganese powder is used, the annealing temperature is 600 °C, and the holding time is 4 h; in Step F2, metallic zinc powder is used, the annealing temperature is 700 °C, and the holding time is 3 h; the air pressure used for the heat treatment in Step H2 is 10 3Pa, at a temperature of 750 °C and an insulation time of 2 h; in Step I2, a hydrochloric acid solution was selected as the chemical etching solution and etched for 8 h.

[0098] Example 4

[0099] The difference from Example 3 is that in Step A2, a copper substrate with a mesh structure was selected.

[0100] Example 5

[0101] The difference from Example 3 is that in Step C2, a mixed metal powder of metal molybdenum powder and metal manganese powder with a particle size of 325 mesh was selected.

[0102] Through testing, it was found that the test results of the above Examples 1 to 5 were basically the same. In order to clearly present the catalytic performance difference between the cathode material with a micro-nano multi-level pore structure provided by the embodiments of the present invention and the existing cathode materials, taking the cathode material with a micro-nano multi-level pore structure prepared in Example 1 as an example, Figure 4 shows the relationship curve (LSV curve) of the potential and current density of the single-cycle test of the catalytic process of the cathode material with a micro-nano multi-level pore structure prepared in Example 1 (performance of 1 st cycle), nickel mesh substrate (Nimesh), and commercial Raney nickel (this commercial Raney nickel is a common catalyst currently used in alkaline hydrogen production electrolyzers). Among them, the test temperature was room temperature, the test system was a standard three-electrode system, the counter electrode was a carbon rod, the reference electrode was a saturated calomel electrode, and the electrolyte was 1.0 M potassium hydroxide solution. The test results are as Figure 4 shown. Figure 4 The abscissa shown is the overpotential (unit: V), and the ordinate is the reference current density (unit: mA·cm -2 ). It should be noted that for the cathode material, its overpotential and current density were analyzed according to their absolute values. From Figure 4 it can be seen that: at the same overpotential, compared with the nickel mesh substrate (Nimesh) and commercial Raney nickel, the cathode material provided by the embodiments of the present invention has a higher absolute value of current density, and is far higher than the absolute value of the current density of the nickel mesh substrate (Nimesh) and commercial Raney nickel. At the same current density, compared with the nickel mesh substrate (Nimesh) and commercial Raney nickel, the cathode material provided by the embodiments of the present invention has a lower absolute value of overvoltage, and is far lower than the absolute value of the overvoltage of the nickel mesh substrate (Nimesh) and commercial Raney nickel. It can be seen from this that the cathode material with a micro-nano multi-level pore structure provided in this embodiment can accelerate the penetration of the electrolyte and the diffusion of H2 bubbles, thereby ensuring the mass transfer efficiency and gas diffusion rate during the hydrogen evolution reaction (HER) process at high current. At the same time, its high specific surface area can expose a large number of catalytic active sites.

[0103] In addition, based on Figure 1 and Figure 2 the scanning electron microscope images of the product of Example 1 shown, it can be clearly seen that the cathode material provided in this embodiment has a sub-micron pore structure and a nano-scale pore structure, and the sub-micron pore structure and the nano-scale pore structure can be uniformly distributed. The sub-micron pore structure presents a double-connected morphology. For the product provided in Example 1, the diameter of the sub-micron pore structure it contains is about 750 nm, and the ligament size is about 750 nm; from Figure 2 it can be known that there is a nano-scale pore structure at the ligament, the diameter of the nano-scale pore structure is about 15 nm, and the size of the ligament formed around the nano-scale pore structure is about 15 nm.

[0104] In summary, the embodiments of the present invention provide the following technical solutions:

[0105] Technical solution 1: A cathode material with a micro-nano multi-level pore structure, which is applied to the hydrogen evolution reaction for catalytic alkaline electrolytic water hydrogen production. The cathode material includes: a transition metal substrate, and an alloy active layer 20 formed on the transition metal substrate, which includes a micron-scale pore structure and / or a sub-micron pore structure 22 and a nano-scale pore structure 23.

[0106] Technical solution 2: The cathode material according to Technical solution 1,

[0107] the alloy active layer 20 further includes: a ligament 21;

[0108] the micron-scale pore structure and / or the sub-micron pore structure 22 is surrounded by the ligament 21;

[0109] the nano-scale pore structure 23 is formed on the ligament 21.

[0110] Technical solution 3: The cathode material according to Technical solution 1,

[0111] the thickness of the alloy active layer 20 is 3 μm to 40 μm.

[0112] Technical solution 4: The cathode material according to Technical solution 2,

[0113] For the cathode material containing the sub-micron pore structure 22, the diameter of the sub-micron pore structure 22 is greater than or equal to 0.7 μm and less than or equal to 1.0 μm;

[0114] and / or,

[0115] For the cathode material containing the micron-scale pore structure, the diameter of the micron-scale pore structure is greater than 1.0 μm and less than or equal to 5.0 μm;

[0116] and / or,

[0117] The diameter of the nanoscale pore structure 23 is 10 nm to 20 nm.

[0118] Technical solution 5. The cathode material according to technical solution 2,

[0119] The pore structures included in the alloy active layer 20 are interconnected and the ligaments 21 included in the alloy active layer 20 are interconnected.

[0120] Technical solution 6. The cathode material according to any one of technical solutions 1 to 5,

[0121] The transition metal substrate includes one of the following transition metals or a metal alloy formed by at least two of the following transition metals:

[0122] Nickel, iron, cobalt, and copper.

[0123] Technical solution 7. The cathode material according to technical solution 6,

[0124] For the structure in which the transition metal substrate contains two or more transition metals, the masses of the various transition metals are the same.

[0125] Technical solution 8. The cathode material according to any one of technical solutions 1 to 5 and 7, the alloy active layer 20 includes:

[0126] The same transition metal as the transition metal substrate, zinc, and at least one of the following first metals:

[0127] The first metal: aluminum, manganese, and molybdenum.

[0128] Technical solution 9. The cathode material according to technical solution 8,

[0129] The same transition metal as the transition metal substrate is derived from the transition metal substrate.

[0130] Technical solution 10. The cathode material according to any one of technical solutions 1 to 5, 7, and 9,

[0131] The transition metal substrate is a foam substrate or a mesh substrate.

[0132] Technical solution 11. A method for preparing a cathode material having a micro-nano multi-stage pore structure, including:

[0133] Step 1. Completely cover the surface of the transition metal substrate with metal powder; under the protection of an inert gas, anneal the transition metal substrate covered with the metal powder to form a primary alloy layer on the transition metal substrate;

[0134] Step 2. Through vapor phase dealloying treatment, form a micron-scale pore structure and / or a submicron-scale pore structure on the primary alloy layer;

[0135] Step 3: Through liquid-phase dealloying treatment, a nano-scale pore structure is further formed on the primary alloy layer having the micron-scale pore structure and / or the sub-micron-scale pore structure, obtaining an alloy active layer 20 including a micron-scale pore structure and / or a sub-micron-scale pore structure 22 and a nano-scale pore structure 23.

[0136] Technical solution 12: According to the preparation method described in Technical solution 11, Step 1 includes:

[0137] Adopt two-step alloying treatment to form a primary alloy layer on the transition metal substrate.

[0138] Technical solution 13: According to the preparation method described in Technical solution 12, Step 1 includes:

[0139] Step 11: Completely cover the surface of the transition metal substrate with the metal powder of the second metal; after 15 min to 30 min in an inert gas environment, anneal the transition metal substrate covered with the metal powder of the second metal at an annealing temperature of 300°C to 1000°C for 0.1 h to 5 h to obtain an intermediate product;

[0140] Step 12: Clean the intermediate product;

[0141] Step 13: Completely cover the surface of the intermediate product with the metal powder of the third metal; under the protection of an inert gas, anneal the intermediate product covered with the metal powder of the third metal at an annealing temperature of 300°C to 1000°C and an annealing time of 0.1 h to 5 h to form a primary alloy layer.

[0142] Technical solution 14: According to the preparation method described in Technical solution 13, characterized in that

[0143] The second metal is one of the following metals: zinc, aluminum, manganese, and molybdenum

[0144] The third metal is one of the following metals: zinc, aluminum, manganese, and molybdenum, and the second metal and the third metal are different metals.

[0145] Technical solution 15: According to the preparation method described in Technical solution 11, Step 2 includes:

[0146] Within the air pressure range of 10 -3 Pa to 10 5 Pa, heat the primary alloy layer at a heating temperature of 300°C to 850°C for 0.5 h to 3.5 h.

[0147] Technical solution 16: According to the preparation method described in any one of Technical solutions 11 to 15, Step 3 includes:

[0148] The primary alloy layer formed with a micron-scale pore structure and / or a sub-micron-scale pore structure is placed in a chemical etching solution for chemical etching treatment to form a nano-scale pore structure.

[0149] Technical solution 17. According to the preparation method described in technical solution 16,

[0150] The chemical etching solution is an alkaline aqueous solution containing at least one of the following alkaline compounds:

[0151] Potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium phosphate, monosodium hydrogen phosphate, potassium phosphate solution, monopotassium hydrogen phosphate, ammonium carbonate, ammonium bicarbonate, and ammonium phosphate;

[0152] Or,

[0153] The chemical etching solution is an acidic aqueous solution containing at least one of the following acidic compounds:

[0154] Sodium dihydrogen phosphate, potassium dihydrogen phosphate, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium monohydrogen phosphate, ammonium dihydrogen phosphate.

[0155] Technical solution 18. According to the preparation method described in technical solution 16,

[0156] The molar concentration of the chemical etching solution is 0.1M to 10M;

[0157] And / or,

[0158] The etching time of the chemical etching solution is 0.1h to 24h;

[0159] And / or,

[0160] The etching temperature of the chemical etching solution is 10°C to 80°C.

[0161] Technical solution 19. The application of the cathode material with a micro-nano multi-level pore structure described in any one of technical solutions 1 to 10 in the hydrogen evolution reaction of catalytic electrolytic water for hydrogen production. The application further includes:

[0162] Using the cathode material with a micro-nano multi-level pore structure as the cathode for catalytic electrolytic water for hydrogen production, and applying a negative electrode potential to the cathode.

[0163] The introduction provided in the above steps is only used to help understand the method, structure, and core idea of the present invention. For those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A cathode material with a micro-nano hierarchical pore structure, characterized in that, Applied to the hydrogen evolution reaction for catalytic alkaline water electrolysis to produce hydrogen, the cathode material includes: a transition metal substrate, and an alloy active layer (20) formed on the transition metal substrate, the alloy active layer (20) including a micron-scale pore structure and / or a sub-micron-scale pore structure (22) and a nano-scale pore structure (23).

2. The cathode material according to claim 1, wherein the alloy active layer (20) further includes: ligaments (21); the micron-scale pore structure and / or the sub-micron-scale pore structure (22) is surrounded by the ligaments (21); the nano-scale pore structure (23) is formed on the ligaments (21).

3. The cathode material according to claim 1, wherein the thickness of the alloy active layer (20) is 3 μm to 40 μm.

4. The cathode material according to claim 2, wherein for the cathode material including the sub-micron-scale pore structure (22), the diameter of the sub-micron-scale pore structure (22) is greater than or equal to 0.7 μm and less than or equal to 1.0 μm; and / or, for the cathode material including the micron-scale pore structure, the diameter of the micron-scale pore structure is greater than 1.0 μm and less than or equal to 5.0 μm; and / or, the diameter of the nano-scale pore structure (23) is 10 nm to 20 nm.

5. The cathode material according to claim 2, wherein the pore structures included in the alloy active layer (20) are interconnected and the ligaments (21) included in the alloy active layer (20) are interconnected.

6. The cathode material according to any one of claims 1 to 5, wherein the transition metal substrate includes one of the following transition metals or a metal alloy formed by at least two of the following transition metals: nickel, iron, cobalt, and copper.

7. The cathode material according to claim 6, wherein for the structure in which the transition metal substrate contains two or more transition metals, the masses of various transition metals are the same.

8. The cathode material according to any one of claims 1 to 5 and 7, characterized in that, The alloy active layer (20) includes: the same transition metal as the transition metal substrate, zinc, and at least one of the following first metals: the first metals: aluminum, manganese, and molybdenum.

9. A method for preparing a cathode material with a micro-nano multi-porous structure, characterized in that, including: Step 1: Completely cover the surface of the transition metal substrate with metal powder; under the protection of an inert gas, anneal the transition metal substrate covered with the metal powder to form a primary alloy layer on the transition metal substrate; Step 2: Through vapor dealloying treatment, form a micron-scale pore structure and / or a sub-micron-scale pore structure on the primary alloy layer; Step 3: Through liquid dealloying treatment, further form a nano-scale pore structure on the primary alloy layer formed with the micron-scale pore structure and / or the sub-micron-scale pore structure to obtain an alloy active layer (20) including a micron-scale pore structure and / or a sub-micron-scale pore structure (22) and a nano-scale pore structure (23).

10. Use of the cathode material with a micro-nano multi-stage pore structure according to any one of claims 1 to 8, characterized in that, Applied to the hydrogen evolution reaction for catalytic water electrolysis to produce hydrogen, the application further includes: using the cathode material with a micro-nano hierarchical pore structure as the cathode for catalytic water electrolysis to produce hydrogen, and applying a negative electrode potential to the cathode.

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