Method for preparing a nanoporous composite, nanoporous composite and applications

Abstract

The application provides a preparation method of a nanoporous composite material, the nanoporous composite material and application, and the method comprises the following steps: mixing a first metal and metal Zn according to an atomic percentage of 10%-20%:80%-90%, and then placing the mixture into a smelting furnace; heating to a molten state under a vacuum environment, and then pouring to form an alloy ingot; grinding the alloy ingot into alloy powder; performing vacuum vapor phase dealloying treatment on the alloy powder to remove Zn in the alloy powder, so as to form a three-dimensionally connected nanoporous first metal; immersing the three-dimensionally connected nanoporous first metal in a salt solution containing second metal ions, and performing annealing in air, so as to form a nanoporous composite material of the first metal / first metal oxide / second metal oxide, wherein the average pore diameter of a plurality of pores in the nanoporous composite material is 80nm-650nm, and the technical scheme solves the problems of low catalytic activity and poor stability of a traditional catalyst material.

Description

Technical Field

[0001] This invention relates to the field of electrochemical material preparation, and in particular to a method for preparing a nanoporous composite material, the nanoporous composite material, and its applications. Background Technology

[0002] The oxygen evolution reaction (OER) plays a crucial role in green electrochemical energy conversion processes such as water splitting, metal-air batteries, and fuel cells, and can significantly alleviate the current energy shortage. However, the slow kinetics of the OER, which involves four-electron transfer, still require a large amount of rare noble metals to drive it and achieve sufficient current density. The OER activity and stability of non-noble metal-based catalysts remain inferior to those of noble metals.

[0003] Currently, rare and precious metal-based catalysts (such as IrO2 or RuO2) are difficult to apply on a large scale in OERs due to their high cost and scarcity. Therefore, much research has been devoted to developing non-precious metal electrocatalysts.

[0004] However, despite the great efforts made to develop cost-effective electrocatalysts, their intrinsic electrocatalytic activity remains unsatisfactory.

[0005] Therefore, how to prepare a catalyst material that can simultaneously improve catalytic activity and long-term stability has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] This invention provides a method for preparing a nanoporous composite material, the nanoporous composite material and its application, to solve the problems of low catalytic activity and poor stability of traditional catalyst materials.

[0007] According to a first aspect of the present invention, a method for preparing a nanoporous composite material is provided, comprising:

[0008] Provide raw materials;

[0009] Alloy preparation: The raw materials are mixed according to atomic percentages and placed in a melting furnace; then heated to a molten state under vacuum and cast to form an alloy ingot; wherein the raw materials include a first metal and metallic Zn; wherein the atomic percentages of the first metal and metallic Zn are 10%~20%:80%~90%;

[0010] Grinding: Grinding the alloy ingot into alloy powder;

[0011] Vacuum-phase dealloying treatment: The alloy powder is subjected to vacuum-phase dealloying treatment to remove Zn from the alloy powder and form a three-dimensional interconnected nanoporous first metal.

[0012] Impregnation: The first metal with three-dimensional interconnected nanoporous structure is impregnated in a salt solution containing second metal ions to deposit the second metal ions on the surface of the first metal with three-dimensional interconnected nanoporous structure, and then annealed in air to form a nanoporous composite material;

[0013] The nanoporous composite material is a composite material of a first metal / a first metal oxide / a second metal oxide, and a plurality of pores are formed in the nanoporous composite material, wherein the average pore size of the plurality of pores is 80 nm to 650 nm.

[0014] Optionally, the first metal is Ni or Co.

[0015] Optionally, the second metal is Ir or Ru.

[0016] Optionally, the following may also be included before grinding:

[0017] The alloy ingot is cut into several alloy blocks;

[0018] The surfaces of the alloy blocks are polished.

[0019] Optionally, the vacuum dealloying process specifically includes:

[0020] The alloy powder is placed in the heating zone of a vacuum tube furnace;

[0021] Use a vacuum pump to reduce the gas pressure inside the tube furnace to 1~10 Pa;

[0022] The temperature inside the tube furnace is controlled at 450~750℃ to heat the alloy powder;

[0023] After holding at the temperature for 0.5 to 3 hours, cool it down with the furnace.

[0024] Optionally, the impregnation process specifically includes:

[0025] The first metal of the three-dimensional interconnected nanoporous structure is immersed in a salt solution containing second metal ions for a first time.

[0026] The impregnated three-dimensional interconnected nanoporous first metal is annealed in air to form the nanoporous composite material.

[0027] Optionally, the salt solution containing the second metal is Ircl3 or Rucl3, and the concentration of Ircl3 or Rucl3 is 50 mmol / L to 80 mmol / L.

[0028] Optionally, the annealing temperature is 150℃~300℃, the annealing time is 40~70 minutes, the annealing atmosphere is air, and the air pressure is atmospheric pressure.

[0029] According to a second aspect of the present invention, a nanoporous composite material is also provided, which is prepared by the method for preparing a nanoporous composite material according to any one of the first aspects of the present invention. The nanoporous composite material has the following composition: a first metal, a first metal oxide, and a second metal oxide; wherein the mass percentages of the first metal, the first metal oxide, and the second metal oxide are 88%:10%:2%.

[0030] The nanoporous composite material includes several pores, and the average pore size of the several pores is 80nm~650nm.

[0031] Optionally, the composition of the nanoporous composite material is: Ni / NiO / IrO2 or Co / CoO / RuO2.

[0032] According to a third aspect of the invention, an application of a nanoporous composite material as described in any one of the second aspects of the invention is provided, wherein the nanoporous composite material is used as an anode catalyst material for alkaline water electrolysis.

[0033] The present invention provides a method for preparing a nanoporous composite material, which involves mixing a first metal and Zn in atomic percentages, heating and casting them under vacuum to form an alloy ingot, then grinding the ingot to obtain alloy powder. The alloy powder is then subjected to vacuum de-alloying treatment to remove Zn, forming a three-dimensional interconnected nanoporous first metal. This three-dimensional interconnected nanoporous first metal is then immersed in a salt solution containing second metal ions and annealed in air to obtain a nanoporous composite material of first metal / first metal oxide / second metal oxide. The nanoporous composite material contains a plurality of pores with an average pore size of 80 nm to 650 nm. Because the nanoporous composite material prepared by this invention has several pores with an average pore size of 80 nm to 650 nm, the pore arrangement can increase the specific surface area, which is beneficial to the transport and exchange of substances. Therefore, compared with traditional rare and precious metal catalyst materials, the rare and precious metal content in the nanoporous composite material of this invention can still maintain good catalytic activity at a very low level (e.g., 1% to 3%), thereby reducing the use of precious metals and saving costs. Furthermore, by depositing a second metal ion, the electronic structure of the first metal in the three-dimensional interconnected nanoporous composite material is improved, which makes the nanoporous composite material have long-term catalytic stability.

[0034] Furthermore, this invention specifically removes Zn from alloy powder through vacuum-phase dealloying, thereby forming a three-dimensional interconnected nanoporous first metal. Compared to traditional methods of forming pores, the Zn in this invention can be recycled, making it more environmentally friendly. Moreover, by controlling the pressure, heating temperature, and reaction time during the vacuum-phase dealloying process, this invention can adjust the pore size of the three-dimensional interconnected nanoporous first metal, resulting in a nanoporous composite material with small pore size and high porosity. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic flowchart of a method for preparing a nanoporous composite material according to an embodiment of the present invention;

[0037] Figure 2 Scanning electron microscope image of the nanoporous composite material prepared by the method for preparing nanoporous composite material provided in Example 1 of the present invention;

[0038] Figures 3(a)-3(e) are energy dispersive spectroscopy (EDS) diagrams of the nanoporous composite materials prepared by the preparation method of the nanoporous composite materials provided in Example 1 of the present invention.

[0039] Figure 4 Scanning electron microscope image of the nanoporous composite material prepared by the method for preparing nanoporous composite material provided in Example 2 of the present invention;

[0040] Figures 5(a)-5(e) are energy dispersive spectroscopy (EDS) diagrams of the nanoporous composite materials prepared by the preparation method of the nanoporous composite materials provided in Example 2 of the present invention.

[0041] Figure 6 Scanning electron microscope image of the nanoporous composite material prepared by the method for preparing nanoporous composite material provided in Example 3 of the present invention;

[0042] Figures 7(a)-7(e) are energy dispersive spectroscopy (EDS) diagrams of the nanoporous composite materials prepared by the preparation method of the nanoporous composite materials provided in Example 3 of the present invention.

[0043] Figure 8 Scanning electron microscope image of the nanoporous composite material prepared by the method for preparing nanoporous composite material provided in Example 4 of the present invention;

[0044] Figures 9(a)-9(e) are energy dispersive spectroscopy (EDS) diagrams of the nanoporous composite materials prepared by the preparation method of the nanoporous composite materials provided in Example 4 of the present invention.

[0045] Figure 10 The oxygen evolution performance diagrams of the nanoporous composite materials prepared by the preparation methods of the nanoporous composite materials provided in Examples 1-4 of the present invention are shown.

[0046] Figure 11 The diagram shows the long-term stability of the oxygen evolution catalysis of the nanoporous composite materials prepared by the preparation methods of the nanoporous composite materials provided in Examples 1-4 of the present invention.

[0047] Figure 12 The diagram shows the oxygen evolution performance of the nanoporous composite materials prepared by the preparation methods of the nanoporous composite materials provided in Comparative Examples 1-2 of the present invention. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0050] The oxygen evolution reaction (OER) plays a crucial role in green electrochemical energy conversion processes such as water splitting, metal-air batteries, and fuel cells, and can significantly alleviate the current energy shortage. However, the slow kinetics of the OER, which involves four-electron transfer, still require a large amount of rare-based noble metals to drive it and achieve sufficient current density. The OER activity and stability of non-noble metal-based catalysts are still inferior to those of noble metals.

[0051] In order to minimize the use of precious metals, the applicant of this application has conducted a series of studies; considering that nanoporous metals, as structure-function integrated materials, have a three-dimensional double continuous open porous structure and high specific surface area, which is conducive to mass transfer within the internal porous channels, the applicant has attempted to prepare nanoporous metals for OER electrocatalysis.

[0052] However, the improvement of the catalytic performance of nanoporous materials is not significant for certain pore sizes.

[0053] In view of this, the inventors of this application propose the following: First metal and Zn are mixed in atomic percentage, heated and cast under vacuum to form an alloy ingot, which is then ground to obtain alloy powder. The alloy powder is then subjected to vacuum dealloying to remove Zn, forming a three-dimensional interconnected nanoporous first metal. This three-dimensional interconnected nanoporous first metal is then immersed in a salt solution containing rare and precious metal ions and annealed in air to obtain a nanoporous composite material of first metal / first metal oxide / rare and precious metal oxide. Because the nanoporous composite material prepared by this invention has several pores, and the arrangement of these pores can increase the specific surface area, which is beneficial for material transport and exchange, the nanoporous composite material of this invention can maintain good catalytic activity even with very low rare and precious metal content, thereby reducing the use of rare and precious metals, saving costs, and exhibiting long-term stability.

[0054] Furthermore, this invention specifically removes metallic Zn from alloy powder by controlling vacuum vapor-phase dealloying, thereby forming a three-dimensional interconnected nanoporous first metal. Compared with traditional methods of forming pores, the metallic Zn in this invention can be recycled, making it more environmentally friendly. Moreover, by controlling the pressure, heating temperature, and reaction time during the vacuum vapor-phase dealloying process, this invention can adjust the pore size of the three-dimensional interconnected nanoporous first metal, enabling the formed nanoporous composite material to have small pore size and high-density pores.

[0055] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0056] Please refer to Figure 1 According to an embodiment of the present invention, a method for preparing a nanoporous composite material is provided, comprising steps S11-S15, as follows:

[0057] S11: Provide raw materials;

[0058] S12: Alloy preparation: The raw materials are mixed according to atomic percentages and placed in a melting furnace; then heated to a molten state under vacuum and cast to form an alloy ingot; wherein the raw materials include a first metal and metallic Zn; wherein the atomic percentages of the first metal and metallic Zn are 10%~20%: 80%~90%;

[0059] S13: Grinding: Grinding the alloy ingot into alloy powder;

[0060] S14: Vacuum dealloying treatment: The alloy powder is subjected to vacuum dealloying treatment to remove Zn from the alloy powder and form a three-dimensional interconnected nanoporous first metal.

[0061] S15: Impregnation: The first metal with three-dimensional interconnected nanoporous structure is impregnated in a salt solution containing second metal ions to deposit the second metal ions on the surface of the first metal with three-dimensional interconnected nanoporous structure, and then annealed in air to form a nanoporous composite material.

[0062] The nanoporous composite material is a composite material of a first metal / a first metal oxide / a second metal oxide, and a plurality of pores are formed in the nanoporous composite material, wherein the average pore size of the plurality of pores is 80 nm to 650 nm.

[0063] In one specific embodiment, the first metal is Ni or Co.

[0064] In one specific embodiment, the second metal is Ir or Ru.

[0065] Of course, it should be recognized that the first metal and the second metal can also be other metals, and the present invention is not limited thereto. Any metal that can achieve the same effect as the present invention is within the protection scope of the present invention.

[0066] The present invention proposes a method for preparing a nanoporous composite material. This involves mixing a first metal and Zn in atomic percentages, heating and casting them under vacuum to form an alloy ingot, then grinding the ingot to obtain alloy powder. The alloy powder is then subjected to vacuum dealloying to remove Zn, forming a three-dimensionally interconnected nanoporous first metal. This three-dimensionally interconnected nanoporous first metal is then immersed in a salt solution containing second metal ions and annealed in air to obtain a nanoporous composite material of first metal / first metal oxide / second metal oxide. This nanoporous composite material contains a plurality of pores with an average pore size of 80 nm to 650 nm. Because the nanoporous composite material prepared by this invention contains a plurality of pores with an average pore size of 80 nm to 650 nm, the pore arrangement increases the specific surface area, which is beneficial for mass transport and exchange. Therefore, the rare and precious metal content in the nanoporous composite material of this invention can maintain good catalytic activity even at very low levels (e.g., low concentrations), thereby reducing the use of rare and precious metals, saving costs, and exhibiting long-term stability.

[0067] In one embodiment, the preparation of the alloy in step S12 specifically includes:

[0068] Weigh the raw materials according to their atomic percentage;

[0069] After mixing the raw materials, they are placed in a crucible in a melting furnace. Under vacuum, the melting furnace is connected to an AC power source and an induced current is applied. The raw materials are melted when the temperature reaches 1173 ~ 1273 K, and the temperature inside the melting furnace is maintained to ensure that the first metal and metallic Zn are completely dissolved.

[0070] The temperature inside the smelting furnace is lowered, and the melt is purified using a refining agent; the purified melt is then degassed in a vacuum furnace.

[0071] The molten material is poured into a preheated cast iron mold to cast an alloy ingot.

[0072] In one embodiment, the raw material composition of a nanoporous composite material is selected from the single-phase region of the nickel-zinc binary alloy phase diagram to avoid phase separation during alloy smelting.

[0073] In one embodiment, the process further includes:

[0074] Cutting the alloy ingot into several alloy blocks and polishing the surfaces of the alloy blocks includes:

[0075] Several alloy ingots are placed into a wire cutting machine, wherein the length of the alloy ingots is, for example, 10-20 cm; irregular parts on the alloy ingots are removed, and the alloy ingots are cut into several alloy blocks;

[0076] The alloy blocks are rinsed with clean water and dried; the alloy blocks are coarsely polished with sandpaper to remove stains from their surfaces; the alloy blocks are finely polished with sandpaper to remove the oxide layer from their surfaces, and then rinsed with deionized water.

[0077] In one embodiment, step S13, grinding the alloy ingot into the alloy powder, specifically includes:

[0078] The alloy blocks are placed in a mortar and ground into alloy powder, and then removed for later use.

[0079] In one embodiment, the vacuum de-alloying process in step S14 specifically includes:

[0080] S141: Placing the alloy powder into the heating zone of a vacuum tube furnace includes:

[0081] The alloy powder is placed in a ceramic boat and then fed into the heating zone of a tube furnace.

[0082] S142: Use a vacuum pump to reduce the gas pressure inside the tube furnace to 1~10 Pa;

[0083] S143: Control the temperature inside the tube furnace to 450~750℃ to heat the alloy powder;

[0084] S144: Keep warm for 0.5~3 hours and then cool with the furnace.

[0085] In this embodiment, the saturated vapor pressure difference between metallic Zn and a first metal under high temperature and high vacuum conditions is used to remove metallic Zn from the alloy, resulting in a three-dimensionally interconnected nanoporous first metal. Compared to traditional methods of forming pores, the metallic Zn in this method can be recycled, making it more environmentally friendly. Furthermore, by controlling the pressure, heating temperature, and reaction time during the vacuum dealloying process, this embodiment can adjust the pore size of the three-dimensionally interconnected nanoporous first metal, enabling the formed nanoporous composite material to possess small pore size and high-density pores.

[0086] In one embodiment, the impregnation process in step S15 specifically includes:

[0087] S151: The first metal of the three-dimensional interconnected nanoporous structure is immersed in a salt solution containing second metal ions for a first time;

[0088] S152: The impregnated three-dimensional interconnected nanoporous first metal is annealed in air to form the nanoporous composite material.

[0089] In one specific embodiment, the salt solution of the second metal in step S51 is IrCl3 or RuCl3, and the concentration of IrCl3 or RuCl3 is 50 mmol / L to 80 mmol / L. In other examples, other salt solutions may be selected, and the present invention is not limited thereto. Any salt solution that can achieve the same effect as the present invention does not depart from the description of this embodiment.

[0090] In one specific embodiment, the annealing temperature in step S52 is 150℃~300℃, the annealing time is 40~70min, the annealing atmosphere is air, and the air pressure is atmospheric pressure.

[0091] In one embodiment, after forming the nanoporous composite material in step S15, the method further includes:

[0092] The nanoporous composite material was washed with deionized water and then washed several times in ultrapure water.

[0093] The nanoporous composite material was dried and stored using a vacuum oven to facilitate structural characterization and electrocatalytic analysis.

[0094] According to another embodiment of the present invention, a nanoporous composite material is also provided, which is prepared by the preparation method of the nanoporous composite material in any one of the foregoing embodiments of the present invention. The composition of the nanoporous composite material is: a first metal, a first metal oxide, and a second metal oxide; wherein the mass percentages of the first metal, the first metal oxide, and the second metal oxide are 88%:10%:2%.

[0095] The nanoporous composite material includes several pores, and the average pore size of the several pores is 80nm~650nm.

[0096] In one embodiment, the nanoporous composite material has the following composition: Ni / NiO / IrO2 or Co / CoO / RuO2.

[0097] In another embodiment, the nanoporous composite material has the following composition: Ni / NiO / RuO2 or Co / CoO / IrO2.

[0098] The nanoporous composite material proposed in this invention comprises a first metal, a first metal oxide, and a second metal oxide; wherein the mass percentages of the first metal, the first metal oxide, and the second metal oxide are 88%:10%:2%; the nanoporous composite material includes a plurality of pores, wherein the average pore size of the plurality of pores is 80 nm to 650 nm. The nanoporous composite material formed by the preparation method of this invention, after vacuum vapor-phase dealloying, can remove metallic Zn. By controlling the pressure, heating temperature, and reaction time during the vacuum vapor-phase dealloying process, the pore size of the nanoporous composite material can be adjusted, resulting in a nanoporous composite material with small pore size and high pore density, thereby increasing the specific surface area of ​​the nanoporous composite material and facilitating mass transport and exchange. Therefore, the nanoporous composite material can maintain high catalytic activity even with a very low content of the second metal, thereby reducing the amount of the second metal used, saving costs, and exhibiting long-term stability.

[0099] According to a third aspect of the invention, an application of a nanoporous composite material as described in any one of the second aspects of the invention is provided, wherein the nanoporous composite material is used as an anode catalyst material for alkaline water electrolysis.

[0100] When the nanoporous composite material of the present invention is used as an anode catalyst in an electrolyzer for alkaline water electrolysis, it can greatly improve the water electrolysis efficiency, achieve the same current density with a lower voltage, and obtain a greater gas output with lower energy consumption.

[0101] Please combine Figure 1 and refer to Figures 2-12 The preparation method of the nanoporous composite material of the present invention will be specifically described below with reference to several specific embodiments. The sources of raw materials, equipment and operation of the equipment involved in the following method for preparing nanoporous composite materials are well known to those skilled in the art, and will not be described in detail here.

[0102] Example 1

[0103] The preparation method of the nanoporous composite material described in Example 1 specifically includes:

[0104] Step S21: Provide raw materials; wherein the raw materials are metallic Ni and metallic Zn; wherein the purity of metallic Ni and metallic Zn is 99.99% or higher.

[0105] Step S22: Alloy preparation: The raw materials are mixed in an atomic percentage ratio of 10%~20%:80%~90% and placed in a crucible in a melting furnace. Under a vacuum of 0.1 Pa, the melting furnace is connected to an AC power source and an induced current of 30.0 A is applied. The raw materials are melted when the temperature reaches 1173~1273 K, and the temperature in the melting furnace is maintained for 10 min. Then, the temperature in the melting furnace is reduced to 1033 K, and the melt is purified using a refining agent. After purification, the melt is degassed in a vacuum furnace for 10 min. The melt is poured into a preheated cast iron mold to cast an alloy ingot. The preheating temperature of the cast iron mold is 1013 K.

[0106] Step S23: Cut the alloy ingot into several alloy blocks and polish the surfaces of the alloy blocks; specifically:

[0107] Several alloy ingots with a length of 10-20cm are placed into a wire cutting machine; irregular portions of the alloy ingots are removed, and the alloy ingots are cut into several alloy blocks; wherein the dimensions of the several alloy blocks are 1cm. 3 ;as well as

[0108] The alloy blocks are rinsed with clean water and dried; the alloy blocks are coarsely polished with 600-grit sandpaper to remove stains from their surfaces; the alloy blocks are finely polished with 1200-grit sandpaper and then rinsed with deionized water.

[0109] Step S24: Grinding: Grinding the alloy ingot into alloy powder, specifically including:

[0110] The alloy blocks are placed in a mortar and ground into alloy powder, which is then taken out for later use; wherein the particle size of the alloy powder is approximately 200 μm.

[0111] Step S25: Vacuum-phase dealloying treatment: The alloy powder is subjected to vacuum-phase dealloying treatment to remove Zn from the alloy powder and form three-dimensional interconnected nanoporous metallic Ni. Step S25 specifically includes steps S251-S254, as follows:

[0112] Step S251: Place the alloy powder into a ceramic boat and send it into the heating zone of the tube furnace;

[0113] Step S252: Use a vacuum pump to reduce the gas pressure inside the tube furnace to 1 Pa and maintain it for 10 min;

[0114] Step S253: Control the temperature inside the tube furnace to 450°C to heat the alloy powder;

[0115] Step S254: After holding at the temperature for 0.5 hours, cool with the furnace.

[0116] In step S25, the saturated vapor pressure difference between metallic Zn and metallic Ni under high temperature and high vacuum conditions is used to remove metallic Zn from the alloy and obtain three-dimensional interconnected nanoporous metallic Ni.

[0117] Step S26: Impregnation: The three-dimensional interconnected nanoporous metal Ni is placed in a solution containing Ir 4+ Ir was deposited on the surface of the three-dimensional interconnected nanoporous metallic Ni by immersion in a salt solution of ions (specifically, an iridium chloride solution). 4+ Ions are annealed in air to form a nanoporous composite material. Step S26 specifically includes steps S261-S262, as follows:

[0118] Step S261: Immerse the three-dimensional interconnected nanoporous metallic Ni in a 50 mmol / L solution containing iridium chloride for 30 min;

[0119] Step S262: Place the impregnated three-dimensional interconnected nanoporous metallic Ni into a crucible, send it into a tube furnace, and heat the three-dimensional interconnected nanoporous metallic Ni at 10℃ / min; anneal to 250℃ in an atmospheric pressure air atmosphere and then cool to room temperature to form the nanoporous composite material; wherein, the annealing time is 60min.

[0120] Step S27: Wash the nanoporous composite material with deionized water and wash it several times in ultrapure water; dry the nanoporous composite material in a vacuum oven at 60°C for 24 hours and then store it; wherein the vacuum degree in the vacuum oven is 0.1 MPa.

[0121] The nanoporous composite material obtained by the method of Example 1 is Ni / NiO / IrO2; and the nanoporous composite material contains a number of pores with an average pore size of 80 nm; wherein the content of Ir element is 1%.

[0122] The scanning electron microscope image of the nanoporous composite material prepared by the method provided in this embodiment is as follows: Figure 2 As shown; by Figure 2 It can be seen that the nanoporous composite material provided in this embodiment has a nanoporous structure morphology, that is, a plurality of pores in the nanoporous composite material. The average pore size of the plurality of pores is 80 nm.

[0123] The energy dispersive spectroscopy (EDS) spectra of the nanoporous composite material prepared by the method provided in this embodiment are shown in Figures 3(a)-3(e). As shown in Figures 3(a)-3(e), the elemental composition of the nanoporous composite material in this embodiment is oxygen, nickel, zinc, and iridium. Figures 3(a)-3(e) show the EDS spectra of the nanoporous composite material and the oxygen, nickel, zinc, and iridium elements therein, respectively. As shown in Figures 3(a)-3(e), oxygen, nickel, zinc, and iridium are uniformly distributed in the nanoporous composite material provided in this embodiment. Oxygen is formed in the nanoporous composite material during its preparation process.

[0124] Example 2

[0125] The preparation method of the nanoporous composite material described in Example 2 is the same as that provided in Example 1, except that the tube furnace temperature and holding time are different when performing vacuum dealloying treatment on the alloy ingot. Specifically, the tube furnace temperature is set to 500°C and the holding time is 1 h. All other parts of steps S21-S25 are the same to obtain the nanoporous composite material of this example.

[0126] The scanning electron microscope image of the nanoporous composite material prepared by the method provided in this embodiment is as follows: Figure 4 As shown; by Figure 4 It can be seen that the nanoporous composite material provided in this embodiment also has a nanoporous structure morphology, that is, a number of pores in the nanoporous composite material; wherein the average pore size of the number of pores is 350 nm.

[0127] The energy dispersive spectroscopy (EDS) spectra of the nanoporous composite material prepared by the method provided in this embodiment are shown in Figures 5(a)-5(e). As can be seen from Figures 5, the elemental composition of the nanoporous composite material in this embodiment is oxygen, nickel, zinc, and iridium. Figures 5(a)-5(e) show the EDS spectra of the nanoporous composite material and its constituent oxygen, nickel, zinc, and iridium, respectively. As can be seen from Figures 5(a)-5(e), oxygen, nickel, zinc, and iridium are uniformly distributed in the nanoporous composite material provided in this embodiment. Oxygen is formed in the nanoporous composite material during its preparation process.

[0128] Example 3

[0129] The preparation method of the nanoporous composite material described in Example 3 is the same as that provided in Example 1, except that the tube furnace temperature and holding time are different when performing vacuum dealloying treatment on the alloy ingot. Specifically, the tube furnace temperature is set to 600°C and the holding time is 1.5h. All other parts of steps S21-S25 are the same to obtain the nanoporous composite material of this example.

[0130] The scanning electron microscope image of the nanoporous composite material prepared by the method provided in this embodiment is as follows: Figure 6 As shown; by Figure 6 It can be seen that the nanoporous composite material provided in this embodiment also has a nanoporous structure morphology, that is, a plurality of pores in the nanoporous composite material; wherein the average pore size of the plurality of pores is 650 nm.

[0131] The energy dispersive spectroscopy (EDS) spectra of the nanoporous composite material prepared by the method provided in this embodiment are shown in Figures 7(a)-7(e). As shown in Figures 7, the elemental composition of the nanoporous composite material in this embodiment is oxygen, nickel, zinc, and iridium. Figures 7(a)-7(e) are the EDS spectra of the nanoporous composite material and the oxygen, nickel, zinc, and iridium elements therein, respectively. As shown in Figures 7(a)-7(e), oxygen, nickel, zinc, and iridium are uniformly distributed in the nanoporous composite material provided in this embodiment. Oxygen is formed in the nanoporous composite material during its preparation process.

[0132] Example 4

[0133] The preparation method of the nanoporous composite material described in Example 4 differs from that in Example 1 only in the raw materials used, the first metal forming a three-dimensional interconnected nanoporous structure through vacuum dealloying, and the salt solution used for impregnation. Specifically, the raw materials used are metallic Co and metallic Zn; the three-dimensional interconnected nanoporous structure formed through vacuum dealloying is metallic Ru; and the salt solution used for impregnation contains Ru. 4+ The ion salt solution (specifically, ruthenium chloride solution); the nanoporous composite material obtained by the method of Example 4 is Co / CoO / RuO2; and the nanoporous composite material contains a number of pores with an average pore size of 80 nm; wherein the content of Ru element is 1%.

[0134] The scanning electron microscope image of the nanoporous composite material prepared by the method provided in this embodiment is as follows: Figure 8 As shown; by Figure 8 It can be seen that the nanoporous composite material provided in this embodiment also has a nanoporous structure morphology, that is, a plurality of pores in the nanoporous composite material; wherein the average pore size of the plurality of pores is 80 nm.

[0135] The energy dispersive spectroscopy (EDS) spectra of the nanoporous composite material prepared by the method provided in this embodiment are shown in Figures 9(a)-9(e). As can be seen from Figures 9, the elemental composition of the nanoporous composite material in this embodiment is oxygen, cobalt, zinc, and ruthenium. Figures 9(a)-9(e) are the EDS spectra of the nanoporous composite material and the oxygen, cobalt, zinc, and ruthenium therein, respectively. As can be seen from Figures 9(a)-9(e), oxygen, cobalt, zinc, and ruthenium are uniformly distributed in the nanoporous composite material provided in this embodiment. Oxygen is formed in the nanoporous composite material during its preparation process.

[0136] The nanoporous composite materials obtained in Examples 1-4 were tested at room temperature using a standard three-electrode system. The counter electrode was a carbon rod, the reference electrode was Hg / HgO, and the electrolyte was a 1.0M KOH aqueous solution saturated with oxygen. Electrocatalytic analysis of the nanoporous composite materials was performed, and the oxygen evolution performance of the nanoporous composite materials is shown in the figure below. Figure 10 As shown; the horizontal axis represents overpotential (unit: V), and the vertical axis represents the reference current density (unit: mA); from Figure 10 It can be seen that the nanoporous composite materials provided in Examples 1-4 only require overpotentials of 198mV, 210mV, 225mV, and 205mV respectively to provide 10 mA cm⁻¹ -2 The reference current density.

[0137] The long-term stability of oxygen evolution catalysis of the nanoporous composite materials obtained in Examples 1-4 is shown in the figure below. Figure 11 As shown; where the vertical axis represents overpotential (unit: V) and the horizontal axis represents catalytic time (unit: h); from Figure 11 It can be seen that at 10mA cm -2 and 500 mA cm -2 Under the reference current density test conditions, the nanoporous composite materials all showed catalytic stability for more than 50 hours.

[0138] Comparative Example 1

[0139] The preparation method of the nanoporous composite material is the same as that provided in Example 1, except that the tube furnace temperature and holding time are different when performing vacuum dealloying treatment on the alloy ingot. The tube furnace temperature is 800°C and the holding time is 3 hours. The average pore size of the pores in the nanoporous composite material is 1000~1500 nm. The content of metal Ir or metal Ru is less than 1%.

[0140] Comparative Example 2

[0141] The preparation method of the nanoporous composite material is the same as that provided in Example 1, except that the tube furnace temperature and holding time are different when performing vacuum dealloying treatment on the alloy ingot. The tube furnace temperature is 350°C and the holding time is 10 min. The nanoporous composite material has a porous structure only on the surface, while the interior is still a blocky structure. The average pore size of the pores in the nanoporous composite material is not uniform. The content of the metal Ir or metal Ru is less than 1%.

[0142] The nanoporous composite materials obtained in Comparative Examples 1 and 2 were tested at room temperature using a standard three-electrode system. The counter electrode was a carbon rod, the reference electrode was Hg / HgO, and the electrolyte was an oxygen-saturated 1.0M KOH aqueous solution. Electrocatalytic analysis of the nanoporous composite materials was performed, and the oxygen evolution performance of the nanoporous composite materials is shown in the figure below. Figure 12 As shown; the horizontal axis represents overpotential (unit: V), and the vertical axis represents the reference current density (unit: mA); from Figure 12 It can be seen that the nanoporous composite materials provided in Comparative Examples 1 and 2 require overpotentials of 298 mV and 339 mV, respectively, to provide 10 mA cm⁻¹. -2 The reference current density.

[0143] For the nanoporous composite materials obtained in Examples 1-4, a vacuum de-alloying method was used to remove metallic Zn, forming three-dimensional interconnected nanoporous metallic Ni or three-dimensional interconnected nanoporous metallic Co. Then, the three-dimensional interconnected nanoporous metallic Ni or three-dimensional interconnected nanoporous metallic Co was impregnated with an Ir-containing... 4+ Or Ru 4+ In a salt solution, Ir 4+ Or Ru 4+ It can be deposited on the surface of three-dimensional interconnected nanoporous metal Ni or three-dimensional interconnected nanoporous metal Co, and after annealing in air, it forms a nanoporous composite material.

[0144] As can be seen from Comparative Examples 1 and 2, when the average pore size of some pores in the nanoporous composite material formed by the present invention is less than 80 nm or more than 650 nm, the specific surface area of ​​the nanoporous composite material decreases, resulting in a decrease in catalytic activity.

[0145] Therefore, the nanoporous composite materials obtained in Examples 1-4 of this application, by setting several pores with appropriate pore size and high density, can improve the specific surface area, which is beneficial to the transport and exchange of substances. Thus, compared with traditional rare and precious metal catalyst materials, the nanoporous composite materials of this invention can still maintain good catalytic activity with very low rare metal content, thereby reducing the use of rare and precious metals, saving costs, and having long-term stability.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing a nanoporous composite material, characterized by, The method comprises the following steps: providing raw materials; preparing an alloy by mixing the raw materials according to atomic percentage and placing the mixed raw materials into a smelting furnace; casting the alloy ingot in a vacuum environment after heating to a molten state; wherein the raw materials comprise a first metal and Zn; the atomic percentage of the first metal and Zn is 10%-20%:80%-90%, and the first metal is Ni or Co; grinding the alloy ingot into an alloy powder; vacuum vapor dealloying the alloy powder to remove Zn in the alloy powder and form a three-dimensionally interconnected nanoporous first metal; immersing the three-dimensionally interconnected nanoporous first metal in a salt solution containing second metal ions to deposit second metal ions on the surface of the three-dimensionally interconnected nanoporous first metal, and performing annealing treatment in air to form a nanoporous composite material; wherein the nanoporous composite material is a composite material of the first metal / first metal oxide / second metal oxide, and a plurality of pores are formed in the nanoporous composite material, the average pore size of the plurality of pores is 80 nm-650 nm, and the mass percentage of the first metal, first metal oxide and second metal oxide is 88%:10%:2%, and the second metal is Ir or Ru.

2. The method of claim 1, wherein the nanoporous composite material is prepared by a process comprising: Before the grinding step, the method further comprises the following steps: cutting the alloy ingot into a plurality of alloy blocks; polishing the surface of the plurality of alloy blocks.

3. The method of claim 1, wherein the nanoporous composite material is prepared by a process comprising: The vacuum vapor dealloying process specifically comprises the following steps: placing the alloy powder into a heating zone of a vacuum tube furnace; reducing the air pressure in the tube furnace to 1-10 Pa by using a vacuum pump; controlling the temperature in the tube furnace to 450-750 DEG C to heat the alloy powder; cooling the alloy powder in the tube furnace after heat preservation for 0.5-3 h.

4. The method of claim 1, wherein the nanoporous composite material is prepared by a process comprising: The immersion process specifically comprises the following steps: immersing the three-dimensionally interconnected nanoporous first metal in a salt solution containing second metal ions for a first time; performing annealing treatment on the immersed three-dimensionally interconnected nanoporous first metal in air to form the nanoporous composite material.

5. The method of claim 4, wherein the nanoporous composite material is prepared by a process comprising: The salt solution containing second metal ions is Ircl3 or Rucl3, and the concentration of the Ircl3 or Rucl3 is 50 mmol / L-80 mmol / L.

6. The method of claim 4, wherein the nanoporous composite material is prepared by a process comprising: The annealing temperature is 150 DEG C-300 DEG C, the annealing time is 40-70 min, the annealing atmosphere is air, and the air pressure is normal pressure.

7. A nanoporous composite material, characterized in that, The nanoporous composite material is prepared by using the method for preparing a nanoporous composite material according to any one of claims 1-6, and the composition of the nanoporous composite material comprises a first metal, a first metal oxide and a second metal oxide; wherein the mass percentage of the first metal, first metal oxide and second metal oxide is 88%:10%:2%. The nanoporous composite material comprises a plurality of pores, and the average pore size of the plurality of pores is 80 nm-650 nm.

8. The nanoporous composite of claim 7, wherein, The composition of the nanoporous composite material is Ni / NiO / IrO2 or Co / CoO / RuO2.

9. Use of a nanoporous composite material as claimed in claim 7 or 8, characterized in that, The nanoporous composite is used as an anode catalyst material for alkaline electrolytic water.

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