CN118272844A - A water electrolysis hydrogen production device with gradient magnetic field and construction method thereof - Google Patents

Abstract

The application belongs to the technical field related to an electrolytic tank, and discloses an electrolytic water hydrogen production device with a gradient magnetic field and a construction method thereof, wherein the device comprises an electrolytic tank, and the electrolytic tank comprises a hydrogen and electrolyte outlet, an oxygen and electrolyte outlet, an anode electrode, a diaphragm, a cathode electrode, a polar plate, an anolyte runner, a catholyte runner and an electrolyte inlet; the surface of the cathode electrode exposed on one side of the catholyte flow channel is adhered with permanent magnet particles, the permanent magnet particles form a gradient magnetic field, and the magnetic field intensity is attenuated from the surface of the cathode electrode to the direction of the catholyte flow channel, so that the magnetic field gradient force applied by hydrogen is perpendicular to the surface of the electrode and is directed to the catholyte flow channel, namely, the desorption process of bubbles on the surface of the electrode is directly promoted, the residence time of the bubbles on the surface of the electrode is reduced, the effective reaction area of the surface of the electrode is increased, the resistivity of electrolyte is reduced, the ohmic loss of electrolytic reaction is reduced, and the energy conversion efficiency of hydrogen production by electrolysis of water is improved.

Description

A water electrolysis hydrogen production device with gradient magnetic field and construction method thereof

Technical Field

The present application belongs to the technical field related to electrolyzers, and more specifically, relates to a water electrolysis hydrogen production device with a gradient magnetic field and a construction method thereof.

Background technique

With the continuous development of new energy technologies, hydrogen has gradually become one of the most promising clean energy sources due to its outstanding advantages such as wide sources, clean combustion products, and high energy density. In recent years, the technology of hydrogen production by water electrolysis has received extensive attention and research, especially in the new power system with new energy as the main body. Hydrogen energy, as a new energy storage medium, has the advantages of large energy storage capacity and long energy storage cycle. By converting excess electrical energy into hydrogen energy through water electrolysis, it can effectively reduce the phenomenon of wind and solar power abandonment, improve the utilization rate of new energy power generation and the stability of power system operation.

The core part of the electrolysis of water to produce hydrogen technology is the electrolyzer, which applies a certain voltage at both ends of the electrolyzer to cause water molecules to undergo an electrolysis reaction, generating oxygen at the anode and hydrogen at the cathode, thereby realizing the conversion of electrical energy into hydrogen energy. As the electrolysis reaction continues, bubbles will be generated on the electrode surface and attached to the electrode surface, reducing the electrochemical active area of the electrode surface, resulting in a smaller effective electrode surface area for the electrolysis reaction. At the same time, the more bubbles there are in the electrolyte, the higher the gas content of the electrolyte between the cathode and anode, which reduces the conductivity of the electrolyte, thereby increasing the ohmic loss during the electrolysis process and reducing the electrolysis efficiency.

Although there are some methods to accelerate the desorption of bubbles, for example, by applying magnetic field forces to the charged ions in the electrolyte to accelerate the disturbance of the electrolyte to reduce bubble attachment, applying magnetic field forces to the charged ions will cause the positive and negative charged ions to move in different directions, which will then interfere with the electric field between the positive and negative electrodes inside the electrolytic cell. Especially when multiple electrolytic chambers are connected in series, the impact is even greater, increasing the uncontrollability of the electrolysis process.

Summary of the invention

In response to the above defects or improvement needs of the prior art, the present application provides a water electrolysis hydrogen production device with a gradient magnetic field and a construction method thereof, the purpose of which is to accelerate the desorption of bubbles on the electrode through the magnetic field while minimizing the impact on the electric field inside the electrolytic cell.

To achieve the above-mentioned purpose, according to one aspect of the present application, there is provided a water electrolysis hydrogen production device with a gradient magnetic field, comprising an electrolytic cell, wherein the electrolytic cell comprises a hydrogen and electrolyte outlet (2), an oxygen and electrolyte outlet (3), an anode electrode (4), a diaphragm (5), a cathode electrode (7), an electrode plate (8), an anode electrolyte flow channel (9), a cathode electrolyte flow channel (10), and an electrolyte inlet (11);

The electrolyte input from the electrolyte inlet (11) flows into the anode electrolyte flow channel (9) and the cathode electrolyte flow channel (10) respectively. The electrolyte flowing into the anode electrolyte flow channel (9) contacts the anode electrode (4) and generates oxygen. The generated oxygen is output from the oxygen and electrolyte outlet (3) along with the electrolyte. The electrolyte flowing into the cathode electrolyte flow channel (10) contacts the cathode electrode (7) and generates hydrogen. The generated hydrogen is output from the hydrogen and electrolyte outlet (2) along with the electrolyte. The anode electrode (4) and the cathode electrode (7) are separated by the diaphragm (5); the electrode plate (8) serves as the peripheral support structure of the electrolytic cell;

Permanent magnet particles (6) are attached to the surface of the cathode electrode (7) exposed to the cathode electrolyte flow channel (10), and the permanent magnet particles (6) form a gradient magnetic field, the magnetic field intensity of which decays in the direction from the surface of the cathode electrode (7) to the cathode electrolyte flow channel (10).

In one of the embodiments, at a surface of the cathode electrolyte flow channel (10) on one side relative to the cathode electrode (7), the magnetic field intensity of the gradient magnetic field formed by the permanent magnet particles (6) has decayed to 0.

In one embodiment, the permanent magnet particles (6) are uniformly attached to the surface of the cathode electrode (7).

In one embodiment, the loading density of the permanent magnet particles (6) attached to the surface of the cathode electrode (7) is in the range of 0.4 to 0.6 mg/m ² .

In one embodiment, the anode electrode (4) and the cathode electrode (7) are both nickel foam material electrodes.

In one embodiment, the particle size of a single permanent magnet particle (6) is less than 2 μm.

In one embodiment, the electrolytic cell further comprises a solenoid magnet coil (13) surrounding the electrolytic cell, wherein the solenoid magnet coil (13) generates a magnetic field directed from the anode electrode (4) to the cathode electrode (7) when current is applied.

In one embodiment, the permanent magnet particles (6) are obtained by magnetizing magnetizable particles, and the magnetizable particles are any one of NdFeB particles, ferrite particles, and cobalt magnetic steel particles.

According to another aspect of the present application, a construction method for preparing a water electrolysis hydrogen production device with a gradient magnetic field as described above is provided, comprising forming permanent magnet particles (6) on the surface of a cathode electrode (7), wherein the cathode electrode (7) is a nickel foam material electrode, and specifically comprising:

The cathode electrode (7) is ultrasonically treated with ethanol, HCl solution and deionized water in sequence to clean the cathode electrode and remove organic matter and oxides on the surface;

Mix magnetizable NdFeB particle powder, 5wt% Nafion solution, deionized water, and isopropanol in the ratio of 18-22mg: 3-5mL: 8-10mL: 25-30mL and stir to form a uniform mixed solution;

Spraying the mixed solution onto the cleaned surface of the cathode electrode (7) and drying it;

A magnetic field is applied to magnetizable NdFeB particles attached to the surface of the cathode electrode (7) for magnetization treatment, thereby obtaining permanent magnet particles (6) having a gradient magnetic field, wherein the magnetic field intensity decays in a direction from the surface of the cathode electrode (7) toward the cathode electrolyte flow channel (10).

In one embodiment, the drying temperature is 55-65° C. and the drying time is 5-8 hours.

In general, compared with the prior art, the above technical solutions conceived by the present application provide a water electrolysis hydrogen production device with a gradient magnetic field and a construction method thereof, which mainly have the following advantages:

Beneficial effects:

1. The present application provides a water electrolysis hydrogen production device with a gradient magnetic field, wherein permanent magnet particles are attached to the surface of the cathode electrode exposed to the cathode electrolyte flow channel, and the permanent magnet particles form a gradient magnetic field, and the magnetic field intensity decays from the cathode electrode surface to the cathode electrolyte flow channel. The present application finds that hydrogen has the characteristic of being able to move in the direction of decreasing magnetic field intensity under a gradient magnetic field. By utilizing this characteristic, permanent magnet particles are arranged on the cathode electrode to produce a magnetic field gradient that meets the requirements, and the magnetic field gradient decreases toward the outside of the cathode electrode, so that the magnetic field gradient force on the hydrogen can be perpendicular to the electrode surface and directed to the cathode electrolyte flow channel, that is, directly promoting the desorption process of bubbles on the electrode surface, reducing the residence time of bubbles on the electrode surface, increasing the effective reaction area of the electrode surface, reducing the resistivity of the electrolyte, reducing the ohmic loss of the electrolysis reaction, and improving the energy conversion efficiency of water electrolysis hydrogen production.

2. The present application provides a water electrolysis hydrogen production device with a gradient magnetic field. Since the permanent magnet particles are only arranged on the cathode electrode, the magnetic field generated is mainly aimed at the substances in the cathode electrolyte flow channel. Therefore, it will not interfere with the substances in the current anode electrolyte flow channel, and the electric field interference between the positive and negative poles of a single electrolytic cell is weak. Moreover, since the magnetic field strength decays in the direction pointing to the anode electrolyte flow channel, when there are multiple parallel electrolysis chambers, the interference to adjacent electrolytic cells is also small. Moreover, due to the use of permanent magnets, only one magnetization is required during the initial preparation, and there is no need to repeatedly magnetize it later.

3. In an embodiment of the present application, a water electrolysis hydrogen production device with a gradient magnetic field is provided. At the side surface of the anode electrolyte flow channel 9 relative to the cathode electrode 7, the magnetic field strength of the gradient magnetic field formed by the permanent magnet particles 6 has decayed to 0. In this way, when there are multiple parallel electrolysis chambers, there is no interference with adjacent electrolytic cells, further improving the controllability of the device.

4. An embodiment of the present application provides a water electrolysis hydrogen production device with a gradient magnetic field, which is equipped with a solenoid magnet coil and applies an adjustable static magnetic field on the basis of the gradient magnetic field, thereby improving the adaptability of the water electrolysis hydrogen production device to different application scenarios and improving the efficiency of converting electrical energy into hydrogen energy.

5. The present application provides a method for constructing a water electrolysis hydrogen production device. For NdFeB particle powder, magnetizable NdFeB particle powder, 5wt% Nafion solution, deionized water, and isopropanol are mixed and stirred in the ratio of 18-22 mg: 3-5 mL: 8-10 mL: 25-30 mL to form a uniform mixed solution. Under this ratio, the NdFeB particles can be evenly dispersed in the mixed solution, and at the same time, the electrode surface reaches a suitable NdFeB particle loading density and ensures its good adhesion on the electrode surface, thereby effectively enhancing the electrolysis process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the internal structure of an electrolytic cell of a water electrolysis hydrogen production device with a gradient magnetic field in one embodiment of the present application;

FIG2 is a schematic structural diagram of an electrolytic cell having multiple electrolytic chambers in one embodiment of the present application;

FIG3 is a schematic structural diagram of a water electrolysis hydrogen production device in another embodiment of the present application;

FIG4 is a flow chart showing the steps of forming permanent magnet particles on the surface of a cathode electrode;

Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

1. Sealing insulating gasket; 2. Hydrogen and electrolyte outlet; 3. Oxygen and electrolyte outlet; 4. Anode electrode; 5. Diaphragm; 6. Permanent magnet particles; 7. Cathode electrode; 8. Pole plate; 9. Anode electrolyte flow channel; 10. Cathode electrolyte flow channel; 11. Electrolyte inlet; 12. End plate; 13. Solenoid magnet coil.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

As shown in Figure 1, this is a schematic diagram of the internal structure of the electrolyzer of the water electrolysis hydrogen production device with a gradient magnetic field in one embodiment of the present application, which includes a hydrogen and electrolyte outlet 2, an oxygen and electrolyte outlet 3, an anode electrode 4, a diaphragm 5, a cathode electrode 7, an electrode plate 8, an anode electrolyte flow channel 9, a cathode electrolyte flow channel 10, and an electrolyte inlet 11. The electrolyte input from the electrolyte inlet 11 flows into the anode electrolyte flow channel 9 and the cathode electrolyte flow channel 10 respectively. The electrolyte flowing into the anode electrolyte flow channel 9 contacts the anode electrode 4 and generates oxygen, and the generated oxygen is output from the oxygen and electrolyte outlet 3 along with the electrolyte. The electrolyte flowing into the cathode electrolyte flow channel 10 contacts the cathode electrode 7 and generates hydrogen, and the generated hydrogen is output from the hydrogen and electrolyte outlet 2 along with the electrolyte. The anode electrode 4 and the cathode electrode 7 are separated by the diaphragm 5; the pole plate 8 serves as the peripheral support structure of the electrolytic cell; wherein, the surface of the cathode electrode 7 exposed to the cathode electrolyte flow channel 10 is attached with permanent magnet particles 6, and the permanent magnet particles 6 form a gradient magnetic field, and the magnetic field intensity decays in the direction from the surface of the cathode electrode 7 to the cathode electrolyte flow channel 10.

In one embodiment, the electrolytic cell is composed of a plurality of electrolytic chambers connected in series, which are compressed by screws and end plates at both ends to form a seal to prevent leakage of the electrolyte. Each electrolytic chamber in the electrolytic cell shares an electrolyte inlet, a hydrogen and electrolyte outlet, and an oxygen and electrolyte outlet. The electrode plate 8 serves as a supporting component of the electrolytic cell, and its function is to support the electrode and the diaphragm and to conduct electricity.

Specifically, the electrolyte flows into the electrolytic chamber from the electrolyte inlet under the action of an external circulation pump, and the water molecules in the electrolyte undergo a reduction reaction on the surface of the cathode electrode 7 to generate hydrogen and hydroxide ions. The hydroxide ions are transported to the anode through the diaphragm 5 and undergo an oxidation reaction on the surface of the anode electrode 4 to generate oxygen. The diaphragm 5 separates the cathode chamber from the anode chamber to prevent the mixing of hydrogen and oxygen, thereby achieving their respective separation. The hydrogen and oxygen produced by the final reaction are respectively mixed with the electrolyte and discharged from the hydrogen and electrolyte outlet 2 and the oxygen and electrolyte outlet 3, and the subsequent gas-liquid separation and electrolyte circulation operations are performed. The chemical equations for the positive and negative electrode reactions of the alkaline electrolytic cell are as follows:

Anode reaction:

Cathode reaction: H ₂ O + 2e ^- → H ₂ ↑ + 2OH ^-

In the present application, the permanent magnet particles 6 are attached to the cathode electrode 7 and form a gradient magnetic field. The magnetic field strength of the formed gradient magnetic field decays in the direction from the surface of the cathode electrode 7 to the cathode electrolyte flow channel 10. Under the action of the gradient magnetic field, the hydrogen formed on the cathode electrode 7 is separated from the cathode electrode 7 by the magnetic field force directed to the cathode electrolyte flow channel 10, which directly promotes the desorption process of the bubbles on the electrode surface, reduces the residence time of the bubbles on the electrode surface, increases the effective reaction area of the electrode surface, reduces the resistivity of the electrolyte, reduces the ohmic loss of the electrolysis reaction, and improves the energy conversion efficiency of hydrogen production by electrolysis of water.

At the same time, the magnetic field gradient force is also proportional to the concentration of the substance being acted on. In the electrolysis chamber, as the hydrogen bubbles generated by the reaction continue to accumulate, the concentration of hydrogen bubbles on the cathode electrode surface along the direction of the electrolyte flow becomes larger and larger. Therefore, a spatially non-uniform magnetic field gradient force will be generated along the direction of the electrolyte flow, which can drive convection to make the gas diffusion layer thinner, reduce overvoltage, and improve electrolysis efficiency. The formula for the magnetic field gradient force on hydrogen is described as follows:

in, represents the magnetic field gradient force density, in N/m ³ ; μ ₀ represents the vacuum magnetic permeability, μ ₀ =4π×10 ^-7 H/m; c represents the substance concentration, in mol/m ³ ; χ _m represents the molar magnetic susceptibility, in m ³ /mol; B represents the magnetic induction intensity, in T. The molar magnetic susceptibility of hydrogen χ _m <0, so the magnetic field gradient force The direction points to the direction where the magnetic induction intensity gradient is negative, that is, the direction where the magnetic induction intensity decreases.

As shown in FIG. 2, a schematic diagram of the structure of an electrolyzer with multiple electrolytic chambers in an embodiment of the present application is shown. The two ends are clamped and fixed by end plates 12, and the plates 8 are sealed by sealing insulating gaskets 1 to prevent electrolyte leakage during the process of electrolyzing water to produce hydrogen. The hydrogen and electrolyte outlets 2, oxygen and electrolyte outlets 3 and electrolyte inlet 11 between the chamber units are aligned with each other to form a common fluid passage. When the electrolysis reaction is carried out, the electrolyte flows into the electrolytic cell from the electrolyte inlet below the end plate and enters each electrolytic chamber. When the voltage applied to the two end plates is greater than the minimum total voltage for the electrolysis reaction to occur, each electrolytic chamber undergoes an electrolysis reaction to generate hydrogen and oxygen. In the proposed structure, the outlet of the gas-liquid mixture is set above the end plate. The advantage is that the upward buoyancy of the gas in the electrolyte can be used to alleviate the accumulation of bubbles between the electrodes, promote the discharge of bubbles, and help reduce ohmic losses.

In this embodiment, several electrolytic chamber units of the proposed structure are connected in series to form a multi-chamber electrolytic cell, and there are attached magnetized particles on the surface of the cathode electrode of each electrolytic chamber, thereby ensuring that the hydrogen bubbles in each electrode chamber are subjected to a strong magnetic field gradient force, thereby ensuring that the effect of the structure will not decay with the increase of the electrolytic chambers; since the attached magnetized particles do not change the main structure of the electrolytic cell, the sealing of each chamber and the mechanical strength of the overall structure of the electrolytic cell are maximized; and the magnetized particles become permanent magnets after being magnetized, and there is no need to repeatedly magnetize them after the magnetization is completed, so that the effect of the magnetic field gradient force will hardly decay over time, thereby ensuring the stability of the effect.

In one embodiment, the gradient magnetic field mainly appears within the micrometer range from the cathode electrode surface and the magnetic field intensity decays rapidly. At the surface of one side of the cathode electrolyte flow channel 10 relative to the cathode electrode 7, the magnetic field intensity of the gradient magnetic field formed by the permanent magnet particles 6 has decayed to 0. In this way, when there are multiple parallel electrolysis chambers, the influence on the electrolysis reaction on the anode side in the adjacent electrode chambers can be ignored, further improving the controllability of the device.

In one embodiment, the permanent magnet particles 6 are uniformly attached to the surface of the cathode electrode 7. On the one hand, the process operation for achieving uniform attachment is simple. On the other hand, when uniformly attached, the force perpendicular to the surface of the cathode electrode 7 is more obvious to the hydrogen, that is, the direction of the force is always perpendicular to and away from the surface of the cathode electrode 7, which is more conducive to the desorption of hydrogen, increases the conductivity of the electrolyte between the electrodes, reduces the ohmic loss, and at the same time increases the effective area of the electrochemical reaction on the electrode surface, thereby improving the efficiency of hydrogen production by electrolysis of water.

Furthermore, the permanent magnet particles 6 are evenly distributed on the surface of the cathode electrode 7, and the load density thereof is in the range of 0.4 to 0.6 mg/m ² . If the load density of the permanent magnet particles 6 is too large, the effective contact area between the cathode electrode and the electrolyte will be affected, thereby affecting the progress of the local reaction; if the load density is too small, the generated gradient magnetic induction intensity is insufficient, the magnetic field gradient force generated on the bubbles is small, and the magnetic field enhancement effect cannot be fully exerted. In this embodiment, the load density of the permanent magnet particles 6 is in the range of 0.4 to 0.6 mg/m ² , so that the effective contact area between the cathode electrode and the electrolyte can be maintained, and the smooth progress of the reaction can be ensured. At the same time, the generated gradient magnetic induction intensity reaches an appropriate level, which is conducive to enhancing the force generated by the magnetic field on the bubbles, thereby improving the efficiency and speed of the electrolysis process.

In one embodiment, the anode electrode 4 and the cathode electrode 7 are both nickel foam electrodes. On the one hand, the structure of nickel foam is more loose and porous, and the specific surface area is larger, so it has more particle attachment sites, and more magnetic particles can be attached, thereby increasing the desorption strength of hydrogen, which is more conducive to the desorption of hydrogen, increasing the conductivity of the electrolyte between the electrodes, reducing ohmic losses, and increasing the effective area of the electrochemical reaction on the electrode surface, thereby improving the efficiency of hydrogen production by electrolysis of water. On the other hand, nickel foam has ferromagnetic properties and will be magnetized in the same direction, so the adhesion between the magnetizable particles and the nickel foam substrate is stronger and not easy to fall off.

Furthermore, the particle size of a single permanent magnet particle 6 is less than 2 μm. The permanent magnet particles 6 within this particle size range are more likely to enter the pores in the foam nickel material electrode, thereby achieving the attachment of more permanent magnet particles.

Optionally, the permanent magnet particles 6 are obtained by magnetizing magnetizable particles, and the magnetizable particles are any one of NdFeB particles, ferrite particles, and cobalt magnetic steel particles.

In one embodiment, the main material of the pole plate (8) in the design structure is stainless steel with low magnetic permeability. According to electromagnetic field theory, its influence on the gradient magnetic field generated on the surface of the cathode electrode can be ignored. The proposed design structure retains the main mechanical structure inside the electrolytic cell, thereby minimizing the influence on the mechanical strength of the device.

As shown in Figure 3, it is a structural schematic diagram of the electrolytic water hydrogen production device in another embodiment of the present application. In this embodiment, the device also includes a solenoid magnet coil 13 around the electrolyzer, and the solenoid magnet coil 13 generates a magnetic field from the anode electrode 4 to the cathode electrode 7 when the current is applied. Specifically, when the current is passed through the solenoid magnet coil, a relatively stable and uniform magnetic field along the axial direction will be generated inside its cavity, and the direction of the magnetic field and the direction of the current in the solenoid tube conform to the right-hand screw rule. For the proposed device, the direction of the static magnetic field applied by the outside world is from the anode to the cathode (the same electrolysis chamber). The inner diameter of the proposed solenoid magnet coil is larger than the radius of the electrolyzer end plate 12, which is convenient for the placement and movement of the electrolyzer inside the solenoid magnetic field coil, and at the same time provides a certain space for the circulation of air, so as to prevent the air temperature inside the solenoid coil cavity from being too high during the electrolysis of the electrolyzer, thereby affecting the normal operation of the electrolytic water hydrogen production device and the solenoid magnet coil. The length of the solenoid magnet coil needs to be greater than the farthest distance between the electrolysis chambers at both ends of the electrolyzer, so that the magnetic field applied by the outside world on the surface of the cathode electrode of each electrolysis chamber is close to a uniform magnetic field. In this embodiment, an approximate uniform magnetic field pointing from the anode to the cathode (the same electrolysis chamber) is applied by the solenoid magnetic field coil outside the electrolyzer, and the superposition of the approximate uniform magnetic field and the original internal gradient magnetic field determines the magnetic induction intensity at the surface of the cathode electrode. By adjusting the magnitude of the current in the solenoid magnetic field coil, the magnitude of the magnetic induction intensity on the surface of the cathode electrode can be changed, thereby adjusting the magnitude of the magnetic field gradient force to which the hydrogen bubbles are subjected. The electrolysis water hydrogen production device can quickly adjust the magnitude of the bubble desorption force in different application scenarios to improve the efficiency of electrolysis water hydrogen production.

Correspondingly, the present application also relates to a construction method for preparing the above-mentioned water electrolysis hydrogen production device with a gradient magnetic field, which construction method includes forming permanent magnet particles 6 on the surface of a cathode electrode 7, the cathode electrode 7 is a nickel foam material electrode, and the permanent magnet particles 6 are formed by magnetizing NdFeB particles.

FIG4 is a flow chart showing the steps of forming permanent magnet particles 6 on the surface of the cathode electrode 7, which includes:

Pretreatment: The cathode electrode was ultrasonically treated with ethanol, HCl solution and deionized water in sequence to clean it and remove organic matter and oxides on the surface;

Mixing: magnetizable NdFeB particle powder, 5wt% Nafion solution, deionized water, and isopropanol are mixed in the ratio of 18-22 mg: 3-5 mL: 8-10 mL: 25-30 mL and stirred to form a uniform mixed solution;

Spraying: spray the mixed solution on the surface of the cleaned cathode electrode and dry it;

Magnetization: A magnetic field is applied to the magnetizable NdFeB particles attached to the surface of the cathode electrode for magnetization treatment to obtain permanent magnet particles with a gradient magnetic field, and the magnetic field intensity decays in the direction from the cathode electrode surface to the cathode electrolyte flow channel.

In one embodiment, the nickel foam is first pretreated, and the nickel foam is ultrasonically treated with ethanol, 1M HCl solution and ultrapure water respectively, and each step lasts for 30 minutes to remove organic matter and oxides on the surface. NdFeB magnetizable particle powder, 5wt% Nafion solution, ultrapure water, and isopropanol are mixed according to 20mg:4mL:9mL:27mL and ultrasonically treated for 1h to form a well-dispersed uniform mixed solution. The mixed solution is then sprayed onto the nickel foam using a spray gun, and the solvent is evaporated with a warm lamp, the drying temperature is 55-65°C, and the drying time is 5-8h. Through the above process, the NdFeB magnetizable particles can be stably attached to the cathode electrode 7.

In the above process, the mixed solution is prepared by mixing magnetizable NdFeB particle powder, 5wt% Nafion solution, deionized water, and isopropanol in the ratio of 18-22mg: 3-5mL: 8-10mL: 25-30mL. The role of adding Nafion solution is to increase the adhesion between the particles and the electrode surface; the role of isopropanol is to disperse the particles and make the particles adhere more evenly. At the same time, the ratio of each component is also the best ratio obtained through experiments. Under this ratio, the NdFeB particles can be evenly dispersed in the mixed solution, and the electrode surface can reach a suitable NdFeB particle load density, and ensure its good adhesion on the electrode surface, thereby effectively enhancing the electrolysis process.

In general, the present application generates a strong gradient magnetic field on the cathode surface through the permanent magnet particles attached to the surface of the cathode electrode inside the electrolyzer, and generates a magnetic field gradient force on the hydrogen. The magnitude of this force is proportional to the magnitude of the magnetic induction intensity and the magnitude of the gradient of the magnetic induction intensity. This force will cause the hydrogen to move in the direction of decreasing magnetic induction intensity, directly promoting the desorption process of the bubble on the electrode surface, reducing the residence time of the bubble on the electrode surface, increasing the effective reaction area of the electrode surface, reducing the resistivity of the electrolyte, reducing the ohmic loss of the electrolysis reaction, and improving the energy conversion efficiency of hydrogen production by electrolysis of water. Moreover, the magnetic field gradient force is also proportional to the concentration of the acting substance. In the electrolysis chamber, as the hydrogen bubbles are continuously accumulated by the reaction, the concentration of hydrogen bubbles on the cathode electrode surface along the direction of the electrolyte flow is increasing, so a spatially uneven magnetic field gradient force will be generated along the direction of the electrolyte flow, which can drive convection to thin the gas diffusion layer, reduce overvoltage, and improve electrolysis efficiency. The device does not need to add a magnetic structure inside the electrolytic cell body to obtain a magnetic field. The proposed design structure retains the main mechanical structure inside the electrolytic cell, thereby minimizing the impact on the mechanical strength of the device. Moreover, since the magnetic field decays rapidly, its impact on the electrolytic reaction on the anode side in the same electrode chamber and adjacent electrode chambers can be ignored, and the impact on the electric field of the entire device is small, making the electrolysis process more controllable.

The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. It should be noted that "in one embodiment", "for example", "for example", etc. in this application are intended to illustrate this application, rather than to limit this application.

The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application.

Claims (10)

1. A water electrolysis hydrogen production device with a gradient magnetic field, characterized in that it comprises an electrolytic cell, wherein the electrolytic cell comprises a hydrogen and electrolyte outlet (2), an oxygen and electrolyte outlet (3), an anode electrode (4), a diaphragm (5), a cathode electrode (7), a plate (8), an anode electrolyte flow channel (9), a cathode electrolyte flow channel (10), and an electrolyte inlet (11); The electrolyte input from the electrolyte inlet (11) flows into the anode electrolyte flow channel (9) and the cathode electrolyte flow channel (10) respectively. The electrolyte flowing into the anode electrolyte flow channel (9) contacts the anode electrode (4) and generates oxygen. The generated oxygen is output from the oxygen and electrolyte outlet (3) along with the electrolyte. The electrolyte flowing into the cathode electrolyte flow channel (10) contacts the cathode electrode (7) and generates hydrogen. The generated hydrogen is output from the hydrogen and electrolyte outlet (2) along with the electrolyte. The anode electrode (4) and the cathode electrode (7) are separated by the diaphragm (5); the electrode plate (8) serves as the peripheral support structure of the electrolytic cell; Permanent magnet particles (6) are attached to the surface of the cathode electrode (7) exposed to the cathode electrolyte flow channel (10), and the permanent magnet particles (6) form a gradient magnetic field, the magnetic field intensity of which decays in the direction from the surface of the cathode electrode (7) to the cathode electrolyte flow channel (10). 2. As claimed in claim 1, the water electrolysis hydrogen production device with a gradient magnetic field is characterized in that: at the side surface of the cathode electrolyte flow channel (10) relative to the cathode electrode (7), the magnetic field intensity of the gradient magnetic field formed by the permanent magnet particles (6) has decayed to 0. 3. The water electrolysis hydrogen production device with a gradient magnetic field as claimed in claim 1, characterized in that the permanent magnet particles (6) are uniformly attached to the surface of the cathode electrode (7). 4. The water electrolysis hydrogen production device with a gradient magnetic field as claimed in claim 2, characterized in that the load density of the permanent magnet particles (6) attached to the surface of the cathode electrode (7) is in the range of 0.4 to 0.6 mg/ ^m2 . 5. The device for producing hydrogen by electrolysis of water with a gradient magnetic field as claimed in claim 1, characterized in that the anode electrode (4) and the cathode electrode (7) are both electrodes made of foamed nickel material. 6. The device for producing hydrogen by electrolysis of water with a gradient magnetic field as claimed in claim 4, characterized in that the particle size of a single permanent magnet particle (6) is less than 2 μm. 7. A water electrolysis hydrogen production device with a gradient magnetic field as claimed in claim 1, characterized in that it also includes a solenoid magnet coil (13) surrounding the electrolytic cell, and the solenoid magnet coil (13) generates a magnetic field pointing from the anode electrode (4) to the cathode electrode (7) when current is applied. 8. The water electrolysis hydrogen production device with a gradient magnetic field as described in any one of claims 1 to 7 is characterized in that: the permanent magnet particles (6) are formed by magnetizing magnetizable particles, and the magnetizable particles are any one of NdFeB particles, ferrite particles, and cobalt magnetic steel particles. 9. A method for preparing a hydrogen production device by electrolysis of water with a gradient magnetic field as claimed in claim 8, characterized in that it comprises forming permanent magnet particles (6) on the surface of a cathode electrode (7), wherein the cathode electrode (7) is a nickel foam material electrode, specifically comprising: The cathode electrode (7) is ultrasonically treated with ethanol, HCl solution and deionized water in sequence to clean the cathode electrode and remove organic matter and oxides on the surface; Mix magnetizable NdFeB particle powder, 5wt% Nafion solution, deionized water, and isopropanol in the ratio of 18-22mg: 3-5mL: 8-10mL: 25-30mL and stir to form a uniform mixed solution; Spraying the mixed solution onto the cleaned surface of the cathode electrode (7) and drying it; A magnetic field is applied to magnetizable NdFeB particles attached to the surface of the cathode electrode (7) for magnetization treatment, thereby obtaining permanent magnet particles (6) having a gradient magnetic field, wherein the magnetic field intensity decays in a direction from the surface of the cathode electrode (7) toward the cathode electrolyte flow channel (10). 10. The construction method according to claim 9, characterized in that the drying temperature is 55-65°C and the drying time is 5-8 hours.