Cold-pressing method for preparing copper electrode and application thereof

Abstract

The present application relates to the preparation of metal copper electrode by cold pressing method and application. With metal nano copper powder as raw material; high hardness stainless steel is used as mold, the weighed powder is poured into the sleeve of the mold, the upper press head of the mold is placed into the sleeve, then the oxygen pipe is connected to the side hole of the mold; the upper press head of the mold is aligned with the center of the press, the pressure head of the hydraulic press is lowered, when the hydraulic press contacts with the upper press head of the mold, the oxygen valve is opened and oxygen is connected, then the pressure is continuously applied and maintained to make the metal powder form; unload the pressure at the same time, close the oxygen valve, use the demolding device to take out the pressed metal copper block, the taken out metal copper block is directly used as catalytic electrode. The prepared metal copper block is directly used as cathode material for electrolytic water hydrogen production or used for electrochemical hydrogen evolution reaction; the overpotential under the current density of 10mA / cm 2 The overpotential under the current density of 10mA / cm

Description

Technical Field

[0001] This invention relates to the fields of metal self-supporting electrode preparation and electrocatalysis, and particularly to the preparation of highly active amorphous copper electrodes for electrochemical hydrogen evolution reaction by cold pressing; specifically, it relates to the preparation of metallic copper electrodes by cold pressing and their applications. Background Technology

[0002] The global energy problem has plagued humanity since the beginning of the new century. The ever-increasing energy demand, the continued depletion of traditional energy sources, and environmental problems caused by pollution have spurred the development of new energy systems to replace traditional energy sources. Hydrogen energy, as a clean and sustainable energy source, is expected to replace finite fossil fuels within the next few centuries. Water electrolysis technology is considered an effective method for converting electrical energy into clean, renewable hydrogen energy with high energy density. Alkaline electrolyzers, in particular, are inexpensive and effectively avoid acid mist and corrosion, making them widely used in industrial green hydrogen production. Metal electrocatalysts play a crucial role in energy conversion and storage. Currently, platinum-based materials are considered the most active catalysts due to their highest exchange current density and lowest overpotential. However, their high price, low yield, and poor stability severely limit their widespread application.

[0003] Copper is abundant and inexpensive, making it a common and potentially valuable conductive material with the potential for applications in electrocatalysis. However, copper has certain inherent properties... 10 The electronic structure of copper and its weak hydrogen adsorption result in very poor catalytic activity for the hydrogen evolution reaction (HER), see: Zhao J et al. ACS Catal. 2015, 5, 4115. Therefore, copper is rarely used as a catalyst for HER. Furthermore, the high surface energy of nanoparticles gives them potentially high catalytic activity, but traditional nano-electrochemical catalytic materials require binders during use, and the coated nanocatalysts are prone to detachment, leading to poor long-term stability. In contrast, self-supporting electrodes are not only stable but also beneficial for industrial application, see: Yang Hetal. Adv. Energy Mater., 2021, 11, 2102074. In summary, the field of electrochemical hydrogen evolution currently lacks catalytic electrodes that offer high activity, high stability, low cost, and ease of large-scale application. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a method for preparing a self-supporting copper electrode using a cold-pressing method. Specifically, copper nanoparticles are pressed in oxygen at room temperature, resulting in an amorphous structure on the surface of the nanoparticles. This self-supporting electrode exhibits greater stability compared to commercially available spray-coated electrocatalysts (such as Raney nickel), and does not detach under high-current operating conditions. Furthermore, compared to other processes requiring harsh conditions to form amorphous structures (such as rapid cooling or high-energy irradiation), we can combine mechanical force and chemical reaction at room temperature, utilizing mild reaction conditions to prepare an amorphous structure. Moreover, this amorphous structure exhibits excellent catalytic activity for the electrolysis of water to produce hydrogen. Specifically, compared to unprocessed copper nanoparticles, it shows superior catalytic activity at 10 mA / cm². 2 The overpotential at the current density was reduced by more than 50%, improving the catalytic performance of copper nanoparticles. This method, which combines mechanical force with chemical reaction to produce an amorphous metal structure with a stable catalytic center by cold-pressing metal nanoparticles in a reaction gas, is not only simple, low-cost, and easy to industrialize, but also modifies inactive copper into a highly active self-supporting hydrogen evolution electrode.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention provides a cold pressing method for preparing metallic copper electrodes, comprising the following steps:

[0007] (1) Using metallic nano copper powder as raw material;

[0008] (2) Use high hardness stainless steel as the mold, pour the weighed powder into the sleeve of the mold, place the upper pressure head of the mold into the sleeve, and then pass the oxygen pipe into the side channel of the mold.

[0009] (3) Align the upper pressure head of the mold with the center of the press, lower the pressure head of the hydraulic press, and when the hydraulic press contacts the upper pressure head of the mold, open the oxygen valve and introduce oxygen, and then continue to apply pressure and maintain it so that the metal powder is formed.

[0010] (4) While unloading the pressure, close the oxygen valve and use the demolding device to remove the pressed copper block. The removed copper block is then used directly as a catalytic electrode.

[0011] The high-hardness stainless steel used as the mold is Cr12.

[0012] The mold consists of an upper pressure head and a sleeve, wherein a channel is opened on the side of the sleeve.

[0013] The pressure required for the upper pressure head is 100MPa-1000 MPa; the pressure holding time is 5min-720min.

[0014] The purity of the aforementioned metallic nano-copper powder should be greater than 99.9%, and the particle size of the nano-copper powder should be 50nm-500nm.

[0015] The mass of the aforementioned metallic nano-copper powder is 2.66*10. -3 D 2 g-5.03*10 -3 D 2 g, where D is the inner diameter of the sleeve, in mm.

[0016] The oxygen flow rate is 3-5 L / min.

[0017] The copper block prepared by the method of the present invention can be directly used as a cathode material for hydrogen production by water electrolysis.

[0018] The copper electrode prepared by the method of the present invention is used for the electrochemical hydrogen evolution reaction.

[0019] Transmission electron microscopy revealed the formation of an amorphous layer on the surface of the copper nanoparticles. Compared to the fully crystalline copper nanoparticles before pressing, the amorphous layer on the particle surface was formed during the cold pressing process. This characterization of the microstructure demonstrates that the cold pressing process induces the formation of an amorphous layer structure on the surface of the copper nanoparticles.

[0020] Electrochemical hydrogen evolution tests were performed on a cold-pressed copper electrode using 1.0 mol / L KOH as the electrolyte. The copper electrode served as the cathode (working electrode) for water electrolysis to produce hydrogen, connected to a three-electrode system (working electrode, reference electrode, and counter electrode). During the test, bubbles continuously emerged from the catalyst surface. The copper electrode exhibited excellent electrochemical hydrogen evolution reaction activity, specifically at 10 mA / cm². 2 The overpotential under the current density can be reduced by more than 50%, which is far greater than that of metal nano-copper particles that have not undergone cold pressing.

[0021] The present invention has the following advantages:

[0022] We prepared amorphous copper electrodes for electrocatalytic hydrogen evolution reaction in alkaline solutions by cold-pressing copper nanoparticles in oxygen at room temperature using a cold-pressing process. In particular, the amorphous structure formed on the particle surface endows them with excellent hydrogen evolution reaction activity, reducing thermodynamic and kinetic barriers during the reaction. The cold-pressed copper electrode catalyst outperformed unprocessed metallic copper nanoparticles in alkaline solutions, and even surpasses previously reported copper-based catalysts. The rapid preparation of highly active amorphous copper catalysts opens a new avenue for producing green and clean hydrogen energy through water electrolysis. Metallic copper is abundant and inexpensive; the cold-pressing process is simple, convenient, and rapid, enabling the quick preparation of metallic electrode materials; and the entire preparation process does not use any toxic raw materials or reagents, making it environmentally friendly. Attached Figure Description

[0023] Figure 1 A diagram of the equipment used in the cold pressing method for preparing amorphous copper electrodes.

[0024] Figure 2 This is a high-magnification transmission electron microscope image of the cold-pressed copper electrode (Cu1) obtained in Example 1.

[0025] Figure 3 The graph shows the polarization curve of the hydrogen evolution reaction of the cold-pressed copper electrode (Cu1) obtained in Example 1.

[0026] Figure 4 The graph shows the polarization curve of the hydrogen evolution reaction of the cold-pressed copper electrode (Cu2) obtained in Example 2.

[0027] Figure 5 The image shows the polarization curve of the hydrogen evolution reaction of the cold-pressed copper electrode (Cu3) obtained in Example 3.

[0028] Figure 6 The graph shows the polarization curve of the hydrogen evolution reaction of the cold-pressed copper electrode (Cu4) obtained in Example 4.

[0029] Figure 7 The graph shows the polarization curve of the hydrogen evolution reaction of the cold-pressed copper electrode (Cu5) obtained in Example 5.

[0030] Figure 8 The image shows the polarization curve of the hydrogen evolution reaction of the cold-pressed copper electrode (Cu6) obtained in Example 6.

[0031] Figure 9 The graph shows the polarization curve of the hydrogen evolution reaction of the cold-pressed copper electrode (Cu7) obtained in Example 7.

[0032] Figure 10 Polarization curves of hydrogen evolution reaction of commercial copper nanoparticles (Cu NPs). Detailed Implementation

[0033] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following embodiments can enable those skilled in the art to have a more comprehensive understanding of the present invention, but do not limit the present invention in any way.

[0034] Supplementary embodiments based on the conditions described in the invention demonstrate that the invention can be achieved under all conditions. All embodiments, specific conditions, and effects are verified.

[0035] Example 1:

[0036] (1) Using metallic nano-copper powder as raw material, its purity is greater than 99.9% and its diameter is 50nm. Taking the inner diameter of the sleeve D=13mm as an example, according to 2.66*10 -3 D 2 g~5.03*10 -3 D 2 Based on the calculation, the mass range of the nano copper powder is 0.45g-0.85g, so take 0.45g of powder.

[0037] (2) High-hardness Cr12 stainless steel with pressure resistance and corrosion resistance is used as the mold. The weighed powder is poured into the sleeve of the mold, and the upper pressure head of the mold is placed into the sleeve. Then the oxygen pipe is inserted into the side channel of the mold.

[0038] (3) Align the upper pressure head of the mold with the center of the press, lower the pressure head of the hydraulic press, and when the hydraulic press contacts the upper pressure head of the mold, open the oxygen valve and introduce oxygen, control the oxygen flow rate to 5L / min, and then continue to apply pressure to 500MPa and maintain this pressure for 5min.

[0039] (4) After the timing is completed, the oxygen valve is closed while the pressure is released. The molded copper block is then removed using a demolding device. The removed copper block can be directly used as a catalytic electrode, such as... Figure 1 As shown.

[0040] The sample obtained in Example 1 is denoted as Cu1. Figure 2 This is a high-magnification transmission electron microscope image of Example 1. The image shows that the outer layer of the copper nanoparticles in Example 1 exhibits a distinct amorphous structure. All these results indicate that an amorphous structure has formed on the surface of Example 1.

[0041] The LSV polarization curves tested in 1.0 mol / L KOH solution in Example 1 are shown below. Figure 3 As can be seen, Example 1 is at 10 mA / cm 2 The overpotential after 90% IR correction at the current density is 96mV. Compared to Figure 10For commercially available metallic copper nanoparticles, the overpotential was reduced by 75.5%.

[0042] Example 2:

[0043] (1) Using metallic nano copper powder as raw material, its purity is greater than 99.9% and its diameter is 50nm. Taking the inner diameter of the sleeve D=13mm as an example, the mass range of nano copper powder is 0.45g-0.85g. Take 0.45g of powder.

[0044] (2) High-hardness Cr12 stainless steel with pressure resistance and corrosion resistance is used as the mold. The weighed powder is poured into the sleeve of the mold, and the upper pressure head of the mold is placed into the sleeve. Then the oxygen pipe is inserted into the side channel of the mold.

[0045] (3) Align the upper pressure head of the mold with the center of the press, lower the pressure head of the hydraulic press, and when the hydraulic press contacts the upper pressure head of the mold, open the oxygen valve and introduce oxygen, control the oxygen flow rate to 4L / min, and then continue to apply pressure to 100MPa and maintain this pressure for 5min.

[0046] (4) After the timing is completed, the oxygen valve is closed while the pressure is released. The molded copper block is then removed using a demolding device. The removed copper block can be directly used as a catalytic electrode, such as... Figure 1 As shown.

[0047] The sample obtained in Example 2 is denoted as Cu2. The LSV polarization curve of Example 2 tested in 1.0 mol / L KOH solution is shown below. Figure 4 As can be seen in Example 2 at 10 mA / cm 2 The overpotential after 90% IR correction at the current density is 134 mV. Compared to Figure 10 For commercially available metallic copper nanoparticles, the overpotential was reduced by 65.8%.

[0048] Example 3:

[0049] (1) Using metallic nano copper powder as raw material, its purity is greater than 99.9% and its diameter is 50nm. Taking the inner diameter of the sleeve D=13mm as an example, the mass range of nano copper powder is 0.45g-0.85g. Take 0.45g of powder.

[0050] (2) High-hardness Cr12 stainless steel with pressure resistance and corrosion resistance is used as the mold. The weighed powder is poured into the sleeve of the mold, and the upper pressure head of the mold is placed into the sleeve. Then the oxygen pipe is inserted into the side channel of the mold.

[0051] (3) Align the upper pressure head of the mold with the center of the press, lower the pressure head of the hydraulic press, and when the hydraulic press contacts the upper pressure head of the mold, open the oxygen valve and introduce oxygen, control the oxygen flow rate to 4L / min, and then continue to apply pressure to 500MPa and maintain this pressure for 120min.

[0052] (4) After the timing is completed, the oxygen valve is closed while the pressure is released. The molded copper block is then removed using a demolding device. The removed copper block can be directly used as a catalytic electrode, such as... Figure 1 As shown.

[0053] The sample obtained in Example 3 is denoted as Cu3. The LSV polarization curve of Example 3 tested in 1.0 mol / L KOH solution is shown below. Figure 5 As can be seen in Example 3 at 10 mA / cm 2 The overpotential after 90% IR correction at the current density is 136mV. Compared to Figure 10 For commercially available metallic copper nanoparticles, the overpotential was reduced by 65.3%.

[0054] Example 4:

[0055] (1) Using metallic nano copper powder as raw material, its purity is greater than 99.9% and its diameter is 50nm. Taking the inner diameter of the sleeve D=13mm as an example, the mass range of nano copper powder is 0.45g-0.85g. Take 0.65g of powder.

[0056] (2) High-hardness Cr12 stainless steel with pressure resistance and corrosion resistance is used as the mold. The weighed powder is poured into the sleeve of the mold, and the upper pressure head of the mold is placed into the sleeve. Then the oxygen pipe is inserted into the side channel of the mold.

[0057] (3) Align the upper pressure head of the mold with the center of the press, lower the pressure head of the hydraulic press, and when the hydraulic press contacts the upper pressure head of the mold, open the oxygen valve and introduce oxygen, control the oxygen flow rate to 3L / min, and then continue to apply pressure to 1000MPa and maintain this pressure for 120min.

[0058] (4) After the timing is completed, the oxygen valve is closed while the pressure is released. The molded copper block is then removed using a demolding device. The removed copper block can be directly used as a catalytic electrode, such as... Figure 1 As shown.

[0059] The sample obtained in Example 4 is denoted as Cu4. The LSV polarization curve of Example 4 tested in 1.0 mol / L KOH solution is shown below. Figure 6 As can be seen in Example 4 at 10 mA / cm 2 The overpotential after 90% IR correction at the current density is 139mV. Compared to Figure 10 For commercially available metallic copper nanoparticles, the overpotential was reduced by 64.5%.

[0060] Example 5:

[0061] (1) Using metallic nano copper powder as raw material, its purity is greater than 99.9% and its diameter is 50nm. Taking the inner diameter of the sleeve D=13mm as an example, the mass range of nano copper powder is 0.45g-0.85g. Take 0.85g of powder.

[0062] (2) High-hardness Cr12 stainless steel with pressure resistance and corrosion resistance is used as the mold. The weighed powder is poured into the sleeve of the mold, and the upper pressure head of the mold is placed into the sleeve. Then the oxygen pipe is inserted into the side channel of the mold.

[0063] (3) Align the upper pressure head of the mold with the center of the press, lower the pressure head of the hydraulic press, and when the hydraulic press contacts the upper pressure head of the mold, open the oxygen valve and introduce oxygen, control the oxygen flow rate to 3L / min, and then continue to apply pressure to 1000MPa and maintain it at this pressure for 720min.

[0064] (4) After the timing is completed, the oxygen valve is closed while the pressure is released. The molded copper block is then removed using a demolding device. The removed copper block can be directly used as a catalytic electrode, such as... Figure 1 As shown.

[0065] The sample obtained in Example 5 is designated Cu5. The LSV polarization curve of Example 5, tested in 1.0 mol / L KOH solution, is shown below. Figure 7 As can be seen in Example 5 at 10 mA / cm 2 The overpotential after 90% IR correction at the current density is 155mV. Compared to Figure 10 For commercially available metallic copper nanoparticles, the overpotential was reduced by 60.5%.

[0066] Example 6:

[0067] (1) Using metallic nano copper powder as raw material, its purity is greater than 99.9% and its diameter is 200nm. Taking the inner diameter of the sleeve D=13mm as an example, the mass range of nano copper powder is 0.45g-0.85g. Take 0.65g of powder.

[0068] (2) High-hardness Cr12 stainless steel with pressure resistance and corrosion resistance is used as the mold. The weighed powder is poured into the sleeve of the mold, and the upper pressure head of the mold is placed into the sleeve. Then the oxygen pipe is inserted into the side channel of the mold.

[0069] (3) Align the upper pressure head of the mold with the center of the press, lower the pressure head of the hydraulic press, and when the hydraulic press contacts the upper pressure head of the mold, open the oxygen valve and introduce oxygen, control the oxygen flow rate to 5L / min, and then continue to apply pressure to 1000MPa and maintain this pressure for 5min.

[0070] (4) After the timing is completed, the oxygen valve is closed while the pressure is released. The molded copper block is then removed using a demolding device. The removed copper block can be directly used as a catalytic electrode, such as... Figure 1 As shown.

[0071] The sample obtained in Example 6 is designated Cu6. The LSV polarization curve of Example 6 tested in 1.0 mol / L KOH solution is shown below. Figure 8 As can be seen in Example 6 at 10 mA / cm 2 The overpotential after 90% IR correction at the current density is 160mV. Compared to Figure 10 For commercially available metallic copper nanoparticles, the overpotential was reduced by 59.2%.

[0072] Example 7:

[0073] (1) Using metallic nano copper powder as raw material, its purity is greater than 99.9% and its diameter is 500nm. Taking the inner diameter of the sleeve D=13mm as an example, the mass range of nano copper powder is 0.45g-0.85g. Take 0.85g of powder.

[0074] (2) High-hardness Cr12 stainless steel with pressure resistance and corrosion resistance is used as the mold. The weighed powder is poured into the sleeve of the mold, and the upper pressure head of the mold is placed into the sleeve. Then the oxygen pipe is inserted into the side channel of the mold.

[0075] (3) Align the upper pressure head of the mold with the center of the press, lower the pressure head of the hydraulic press, and when the hydraulic press contacts the upper pressure head of the mold, open the oxygen valve and introduce oxygen, control the oxygen flow rate to 5L / min, and then continue to apply pressure to 1000MPa and maintain this pressure for 5min.

[0076] (4) After the timing is completed, the oxygen valve is closed while the pressure is released. The molded copper block is then removed using a demolding device. The removed copper block can be directly used as a catalytic electrode, such as... Figure 1 As shown.

[0077] The sample obtained in Example 7 is designated Cu7. The LSV polarization curve of Example 7, tested in 1.0 mol / L KOH solution, is shown below. Figure 9 As can be seen in Example 7 at 10 mA / cm 2 The overpotential after 90% IR correction at the current density is 191 mV. Compared to Figure 10 For commercially available metallic copper nanoparticles, the overpotential was reduced by 51.3%.

[0078] In summary, cold pressing copper nanoparticles in oxygen at room temperature creates an amorphous structure on the surface of the metal nanoparticles. In 1.0 mol / L KOH solution, it exhibits excellent hydrogen evolution reaction activity at 10 mA / cm². 2 The overpotential at the current density can be reduced by more than 50%, far exceeding that of unprocessed copper nanoparticles. This inexpensive catalytic electrode with high catalytic activity has a wide range of applications.

[0079] The technical solutions disclosed and proposed in this invention can be implemented by those skilled in the art by appropriately modifying the conditions and routes, etc. Although the methods and preparation techniques of this invention have been described through preferred embodiments, those skilled in the art can obviously modify or recombine the methods and technical routes described herein without departing from the content, spirit, and scope of this invention to achieve the final preparation technique. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within the spirit, scope, and content of this invention.

Claims

1. A method for producing a copper electrode by cold-pressing method, characterized by, It comprises the following steps: (1) taking metal nano-copper powder as raw material; (2) taking high-hardness stainless steel as mold, pouring the weighed powder into the sleeve of the mold, placing the upper press head of the mold into the sleeve, and then passing oxygen pipe into the side hole of the mold; (3) aiming the upper press head of the mold at the center of the press, lowering the press head of the hydraulic machine, opening the oxygen valve and passing oxygen when the hydraulic machine contacts the upper press head of the mold, and then continuously applying pressure and keeping the metal powder shaped; (4) closing the oxygen valve while unloading the pressure, taking out the pressed metal copper block by using the demolding device, and directly using the taken-out metal copper block as catalytic electrode.

2. The production method according to claim 1, wherein The high-hardness stainless steel as mold is Cr12.

3. The production method according to claim 1, wherein The mold is composed of upper press head and sleeve, and the sleeve has a side hole.

4. The production method according to claim 3, wherein The required pressure of the upper press head is 100 MPa-1000 MPa; the pressure keeping time is 5 min-720 min.

5. The production method according to claim 3, wherein The purity of the metal nano-copper powder should be greater than 99.9%, and the particle size of the nano-copper powder is 50 nm-500 nm.

6. The production method according to claim 3, wherein The mass of the metal nano-copper powder is 2.66*10 -3 D 2 g-5.03*10 -3 D 2 g, wherein D is the inner diameter of the sleeve, in mm.

7. The production method according to claim 3, wherein The flow rate of the passed oxygen is 3-5 L / min.

8. The metal copper electrode prepared by the preparation method of claim 1 is directly used as cathode material for hydrogen production by electrolysis of water.

9. The metal copper electrode prepared by the preparation method of claim 1 is used for electrochemical hydrogen evolution reaction.

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