Alkaline water electrolysis hydrogen production electrode and preparation method thereof

Abstract

The invention belongs to the technical field of water electrolysis hydrogen production, and particularly relates to an alkaline water electrolysis hydrogen production electrode and a preparation method thereof. The preparation method comprises the following steps: S1, performing texturing treatment on the surface of an electrode substrate to obtain an electrode precursor; s2, carrying out aging treatment on the electrode precursor; and S3, carrying out heat treatment on the electrode precursor subjected to aging treatment in a reducing atmosphere to obtain the lithium ion battery electrode. According to the preparation method, through texturing treatment, aging treatment and reduction heat treatment, the active sites and the specific surface area of the electrode base material are increased, the conductivity is improved, and the prepared electrode has good catalytic activity, high stability and low cost.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen production by electrolysis of water, and specifically relates to an alkaline water electrolysis hydrogen production electrode and a preparation method thereof. Background Art

[0002] In recent years, hydrogen energy has received extensive attention due to its pollution-free, wide source and high conversion efficiency. Among the current hydrogen production technologies, water electrolysis is the greenest way to produce hydrogen, with the advantages of high purity, simple process, no pollution and abundant sources. Industrial water electrolysis hydrogen production technology has been developed for more than 100 years, but the electrolyzer, as the core component of water electrolysis hydrogen production, still consumes a relatively high cost, of which the electrode accounts for about 35% of the cost of the electrolyzer.

[0003] Commercially, the current method is to spray nickel-aluminum mixed or nickel-aluminum alloy powder on the substrate, and then use a leaching solution to leach part of the aluminum to prepare electrodes for alkaline water electrolysis hydrogen production. This method is widely accepted due to its high processing efficiency, but the electrode coating prepared by this method has a high risk of falling off, and the additive manufacturing method leads to high costs. Summary of the invention

[0004] In view of the defects existing in the prior art, the present invention proposes a low-cost, high-stability alkaline water electrolysis hydrogen production electrode and a preparation method thereof, and adopts the methods of roughening treatment, aging treatment and reduction heat treatment to increase the active sites during the electrode reaction. The selected aging temperature and time can cause lattice distortion on the surface of the substrate, resulting in an uneven surface of the substrate and an increase in specific surface area. The three treatment methods are progressively applied layer by layer to finally prepare a low-cost, high-stability alkaline water electrolysis hydrogen production electrode.

[0005] Specifically, the present invention provides the following technical solutions:

[0006] A method for preparing an electrode for producing hydrogen by electrolysis of alkaline water comprises the following steps:

[0007] S1, roughening the surface of the electrode substrate to obtain an electrode precursor;

[0008] S2, subjecting the electrode precursor to aging treatment;

[0009] S3. The electrode precursor after aging treatment is subjected to heat treatment in a reducing atmosphere to obtain.

[0010] The above-mentioned preparation method provided by the present invention first increases the surface roughness of the electrode substrate by surface texturing treatment, then removes the stress introduced by the weaving and texturing processes by high-temperature aging treatment, and forms a second phase to change the crystal structure, which is macroscopically manifested as an uneven surface and increased surface roughness. Finally, high-temperature reduction of the surface oxide increases the conductivity, and the vacancies left after the oxygen atoms are taken away further increase the specific surface area.

[0011] Preferably, in step S1, the material of the electrode substrate is one or more of nickel, iron, and chromium.

[0012] Preferably, in step S1, the electrode substrate is a nickel wire mesh. The electrode of the present invention is used for hydrogen production by alkaline water electrolysis, so the substrate is preferably a nickel material that is resistant to alkali corrosion. Another common nickel material is nickel foam, but studies have found that if nickel foam is used, it cannot withstand high-temperature oxidation and the substrate will become "brittle".

[0013] Preferably, in step S1, the surface of the electrode substrate is first degreased and cleaned, and then roughened.

[0014] Preferably, in step S1, the specific operation of the roughening treatment is: using one of white corundum, brown corundum and red corundum with a mesh size of 60-100 to perform sandblasting roughening treatment, and the surface roughness after treatment is greater than Ra25.

[0015] Preferably, in step S2, the specific operation of the aging treatment is: keep the electrode precursor at 950-1050°C for 120-200 minutes and then cool it. If the aging treatment time is too short, the second phase will not be formed or will not be formed sufficiently, which is manifested as the surface roughness of the substrate is too low. If the aging treatment time is too long, it will cause the substrate to break at high temperature, which is also not conducive to improving the catalytic performance. Therefore, it is most appropriate to control the aging treatment time to 120-200 minutes. Among them, when the aging time is 160 minutes, the surface roughness of the electrode precursor is large and the mechanical properties meet the technical requirements of water electrolysis hydrogen production.

[0016] In addition, the study found that if the aging treatment temperature is lower than 950°C, the second phase will not be formed or will be insufficiently formed; if the aging treatment temperature is higher than 1050°C, the strength of the substrate will deteriorate and cannot be used normally.

[0017] More preferably, the heating rate of the aging treatment is 4°C / min to 6°C / min.

[0018] Preferably, in step S3, the specific operation of the heat treatment is: keeping the electrode precursor after aging treatment at 400-600°C for 60-200 minutes and then cooling it. Studies have found that if the aging treatment temperature is lower than 400°C, the reduction effect is poor and the electrode conductivity is poor; if the aging treatment temperature is higher than 600°C, the reduction effect is close to 600°C, but the electrode strength deteriorates.

[0019] More preferably, the heating rate of the heat treatment is 4°C / min to 6°C / min.

[0020] Preferably, in step S3, the reducing atmosphere is one or more of hydrogen, carbon monoxide, and natural gas.

[0021] The present invention also provides an alkaline water electrolysis hydrogen production electrode, which is prepared by the above-mentioned preparation method.

[0022] The present invention also provides the alkaline water electrolysis hydrogen production electrode, or the use of the alkaline water electrolysis hydrogen production electrode prepared by the above preparation method in alkaline water electrolysis hydrogen production.

[0023] Beneficial effects achieved by the present invention:

[0024] (1) The present invention provides a method for preparing an alkaline water electrolysis hydrogen production electrode. Under the premise of not using additive manufacturing and not containing any coating, the performance and structure of the existing electrode substrate are optimized through roughening treatment, aging treatment, and reduction heat treatment. The prepared electrode exhibits good catalytic activity. At the same time, compared with the existing coated electrode, the lack of element introduction ensures lower cost, lower risk of shedding, and good stability.

[0025] (2) The present invention provides a method for preparing an alkaline water electrolysis hydrogen production electrode, which ensures that it has good catalytic activity and electrode strength by regulating the aging treatment temperature and time, as well as the reduction heat treatment temperature and time.

[0026] (3) The present invention provides a method for preparing an alkaline water electrolysis hydrogen production electrode, which requires simple equipment, convenient process operation, and controllable conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a surface morphology image of the electrode precursor after aging treatment in Example 1 after being magnified 50 times.

[0028] Figure 2 This is a surface morphology image of the water electrolysis hydrogen production electrode after reduction heat treatment in Example 1, magnified 50 times.

[0029] Figure 3 This is a comparison chart of the hydrogen evolution performance of the water electrolysis hydrogen production electrode prepared in Example 1 and the nickel-aluminum electrode.

[0030] Figure 4 This is a comparison chart of the oxygen evolution performance of the water electrolysis hydrogen production electrode prepared in Example 1 and the nickel-aluminum electrode. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention is described clearly and completely below. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention. If no specific technology or conditions are specified in the embodiments, the technology or conditions described in the literature in the field or the product instructions are used.

[0032] Example 1

[0033] A 40-mesh nickel wire mesh (brand N6) was degreased and dried, and a sandblasting machine was loaded with 80-mesh white corundum to perform sandblasting pretreatment on the nickel mesh to make its surface rough (roughness greater than Ra25), thereby preparing a water electrolysis hydrogen production electrode precursor 1.

[0034] The prepared electrode precursor 1 was placed in an air atmosphere sintering furnace, the gas inlet and outlet of the sintering furnace were kept open to ensure air circulation in the furnace, the temperature was raised to 600°C at a heating rate of 6°C / min, and then raised to 1000°C at a heating rate of 4°C / min, and maintained for 160 minutes. After the aging treatment, it was cooled in the furnace to obtain a modified and optimized electrode precursor 2.

[0035] The prepared electrode precursor 2 is placed in the sintering furnace again, and the air in the furnace is replaced with nitrogen for multiple times to make its oxygen content ≤0.5%. Hydrogen is introduced until the pressure in the furnace is -0.07 MPa, and the temperature is increased to 600°C at a heating rate of 6°C / min and maintained for 120 minutes. After the heat treatment is completed, it is cooled in the furnace to obtain a low-cost, high-stability water electrolysis hydrogen production electrode.

[0036] Figure 1 This is a 50-fold magnified surface morphology of the electrode precursor after aging treatment in Example 1. Figure 1 It can be seen that the electrode precursor 2 after aging treatment is better than lattice deformation, the surface has become uneven, and the specific surface area is greatly improved compared with the untreated substrate.

[0037] Figure 2 This is a 50-fold magnified surface morphology of the water electrolysis hydrogen production electrode after reduction heat treatment in Example 1. Figure 2 It can be seen that after reduction heat treatment, the electrode surface changes from dark black to bright silver, which indicates that the oxide on the electrode surface has been reduced, and the oxygen vacancies formed during the reduction further increase the specific surface area of ​​the electrode.

[0038] The performance of the commercially available sprayed nickel-aluminum electrode and the electrode prepared in Example 1 was tested by a linear potential scanning test method. A three-electrode system was used, the prepared electrode was a working electrode, the working electrode size was 1×1 cm, Hg / HgO was a reference electrode, a platinum sheet was an auxiliary electrode, and a KOH solution with a mass fraction of 30% was selected as the electrolyte. The scanning rate was 50 mV / s, the hydrogen evolution scanning range was -0.7 V to -1.6 V, and the oxygen evolution scanning range was 0 V to 0.8 V. The hydrogen evolution and oxygen evolution performances were tested on an electrochemical workstation (CS300M) and were slightly better than those of the sprayed nickel-aluminum electrode. After a period of testing, there was no obvious attenuation phenomenon. For details, see Figure 3 , Figure 4 shown.

[0039] Example 2

[0040] The electrode precursor 1 prepared in Example 1 is placed in an air atmosphere sintering furnace, the gas inlet and outlet of the sintering furnace are kept open to ensure air circulation in the furnace, the temperature is increased to 600°C at a heating rate of 6°C / min, and then the temperature is increased to 1000°C at a heating rate of 4°C / min, and the temperature is kept at this temperature for 120 minutes. After the aging treatment is completed, the electrode precursor 2 is cooled with the furnace to obtain a modified and optimized electrode precursor 2.

[0041] The prepared electrode precursor 2 is placed in the sintering furnace again, and the air in the furnace is replaced with nitrogen for multiple times to make its oxygen content ≤0.5%. Hydrogen is introduced until the pressure in the furnace is -0.07 MPa, and the temperature is increased to 600°C at a heating rate of 6°C / min and kept at this temperature for 80 minutes. After the heat treatment is completed, it is cooled in the furnace to prepare a water electrolysis hydrogen production electrode.

[0042] Example 3

[0043] The electrode precursor 1 prepared in Example 1 is placed in an air atmosphere sintering furnace, the gas inlet and outlet of the sintering furnace are kept open to ensure air circulation in the furnace, the temperature is increased to 1000°C at a heating rate of 4°C / min, and the temperature is kept for 160 minutes. After the aging treatment is completed, the electrode precursor 2 is cooled with the furnace to obtain a modified and optimized electrode precursor 2.

[0044] The prepared electrode precursor 2 is placed in the sintering furnace again, and the air in the furnace is replaced with nitrogen for multiple times to make its oxygen content ≤0.5%. Hydrogen is introduced until the pressure in the furnace is -0.07 MPa, and the temperature is increased to 600°C at a heating rate of 6°C / min and kept warm for 120 minutes. After the heat treatment is completed, it is cooled in the furnace to prepare a water electrolysis hydrogen production electrode.

[0045] Example 4

[0046] The electrode precursor 1 prepared in Example 1 is placed in an air atmosphere sintering furnace, the gas inlet and outlet of the sintering furnace are kept open to ensure air circulation in the furnace, the temperature is increased to 600°C at a heating rate of 6°C / min, and then the temperature is increased to 1050°C at a heating rate of 4°C / min, and the temperature is kept for 160 minutes. After the aging treatment is completed, it is cooled in the furnace to obtain a modified and optimized electrode precursor 2.

[0047] The prepared electrode precursor 2 is placed in the sintering furnace again, and the air in the furnace is replaced with nitrogen for multiple times to make its oxygen content ≤0.5%. Hydrogen is introduced until the pressure in the furnace is -0.07 MPa, and the temperature is increased to 600°C at a heating rate of 6°C / min and kept warm for 120 minutes. After the heat treatment is completed, it is cooled in the furnace to prepare a water electrolysis hydrogen production electrode.

[0048] Although the present invention has been described in detail above by general description, specific implementation methods and experiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A method for preparing an electrode for producing hydrogen by electrolysis of alkaline water, characterized in that: The following steps are involved: S1, roughening the surface of the electrode substrate to obtain an electrode precursor; S2, subjecting the electrode precursor to aging treatment; S3. The electrode precursor after aging treatment is subjected to heat treatment in a reducing atmosphere to obtain.

2. The preparation method according to claim 1, characterized in that: In step S1, the electrode substrate is a nickel wire mesh.

3. The preparation method according to claim 1 or 2, characterized in that: In step S1, the specific operation of the roughening treatment is: using one of 60-100 mesh white corundum, brown corundum and red corundum for sandblasting roughening treatment, and the surface roughness after treatment is greater than Ra25.

4. The preparation method according to claim 1 or 2, characterized in that: In step S2, the specific operation of the aging treatment is: keeping the electrode precursor at 950-1050°C for 120-200 minutes and then cooling it.

5. The preparation method according to claim 1 or 2, characterized in that: In step S3, the specific operation of the heat treatment is: keeping the electrode precursor after aging treatment at 400-600°C for 60-200 minutes and then cooling it.

6. The preparation method according to claim 1 or 2, characterized in that: In step S3, the reducing atmosphere is one or more of hydrogen, carbon monoxide, and natural gas.

7. An alkaline water electrolysis hydrogen production electrode, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 6.

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