A method for preparing a catalytic electrode for producing hydrogen by alkaline water electrolysis

Abstract

The present invention discloses a method for preparing a catalytic electrode for producing hydrogen by alkaline water electrolysis, comprising the following steps: (1) selecting a plasma spraying technology to prepare the catalytic electrode for producing hydrogen by alkaline water electrolysis; (2) determining the alloy density; (3) establishing a relationship between the spraying scanning speed and the coating thickness during the plasma spraying process; (4) determining the optimal spraying thickness according to the relationship between the spraying thickness and the electrode performance; and then calculating the spraying scanning speed through step (3), and setting parameters according to the obtained spraying scanning speed value to complete plasma spraying. The preparation method of the present invention determines the optimal spraying thickness according to the relationship between the spraying thickness and the electrode performance, and uses the formula established in the method steps to calculate, so that the corresponding spraying scanning speed can be quickly obtained for parameter setting, and plasma spraying can be completed without repeatedly performing spraying tests to determine the operating process; the present invention can ensure electrode performance, improve product quality, and is suitable for industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of plasma spraying, and in particular to a method for preparing a catalytic electrode for producing hydrogen by alkaline water electrolysis. Background Art

[0002] Hydrogen production by water electrolysis is a green method of hydrogen production and is also the most promising method of hydrogen production at present. It can improve the utilization rate of intermittent renewable energy. At present, the main factor restricting the industrial application of water electrolysis hydrogen production technology is the cost of electricity. During the water electrolysis reaction, the kinetics of the anode oxygen evolution reaction is slow, the overpotential is high, and the energy consumption is high. Therefore, it is necessary to develop highly active and stable catalytic electrodes for water electrolysis hydrogen production to achieve higher electrolysis voltage and higher current density.

[0003] At present, the main methods for preparing catalytic electrodes include hydrothermal synthesis, electrodeposition, magnetron sputtering and plasma spraying. The hydrothermal synthesis method requires a long reaction time, the binding force between the catalyst and the carrier is weak, and the catalyst is prone to fall off during the water decomposition process. Although the electrodeposition method can produce more active sites, it makes it difficult to control the grains of the growing catalyst, and the thickness of the coating will also affect the efficiency of water decomposition. These factors make it impossible to achieve industrialization. The catalyst prepared by magnetron sputtering has a strong binding force with the carrier, but the uniformity of the coating is poor, the catalytic active sites are few, and it does not show excellent performance during water decomposition. Plasma spraying technology uses a plasma arc driven by direct current as a heat source to heat ceramics, alloys, metals and other materials to a molten or semi-molten state, and sprays them at high speed onto the pre-treated workpiece surface to form a firmly attached surface layer. Plasma sprayed electrodes have high temperature stability, good electrical and thermal conductivity, and can provide reliable performance within the maximum service life of the electrode. All process parameters of plasma spraying can be quantitatively controlled, and the coating has good reproducibility. During the spraying process, the coating thickness will affect the coating bonding strength, hardness, porosity, etc., which in turn affects the electrode performance. Existing plasma spraying processes often require repeated spraying tests to determine the operating process, which has complex steps, poor quality consistency, and cannot effectively ensure electrode performance. Therefore, it is crucial to accurately determine the actual operating process based on parameters such as the optimal coating thickness. Summary of the invention

[0004] Based on the above technical problems, the present invention proposes a method for preparing a catalytic electrode for hydrogen production by alkaline water electrolysis at normal pressure to solve the problems in the preparation process of the catalytic electrode for hydrogen production by water electrolysis, thereby promoting the industrial application of alkaline water electrolysis hydrogen production technology.

[0005] The technical solution adopted by the present invention is:

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

[0007] (1) Using plasma spraying technology to prepare catalytic electrodes for hydrogen production from alkaline water electrolysis;

[0008] (2) Determine the alloy density using the following formula (1);

[0009]

[0010] In formula (1), m1 is the mass of material 1 in g, m2 is the mass of material 2 in g, and m n is the mass of material n, g; ρ1 is the density of material 1, g / mm 3 , ρ2 is the density of material 2 g / mm 3 , ρ n is the density of material n g / mm 3 ;

[0011] (3) Establish the relationship between the spray scanning speed and the coating thickness during the plasma spraying process, as shown in the following formula (2):

[0012]

[0013] In formula (2), v 送 is the powder feeding speed g / s, ρ is the alloy density g / mm 3 , h is the coating thickness (mm), d is the coating diameter sprayed onto the substrate (mm), v 扫 is the spray scanning speed mm / s;

[0014] (4) Determine the optimal spraying thickness based on the relationship between the spraying thickness and the electrode performance; then calculate the spraying scanning speed through step (3), and set the parameters according to the obtained spraying scanning speed value to complete the plasma spraying.

[0015] Preferably, step (2) further comprises the step of preparing the catalyst coating powder:

[0016] Two or more metals are mixed in proportion, melted and mixed in a high-frequency furnace, and after cooling, put into a pulverizer to crush into powder to obtain catalyst coating powder.

[0017] Preferably, in step (3): the powder feeding speed is selected to be 10-200 g / min.

[0018] Preferably, step (4) further comprises the following steps:

[0019] Place the substrate to be sprayed on the spraying tooling and fix it, put the catalyst coating powder into the material barrel of the powder feeding mechanism, and set the powder feeding speed; fix the plasma gun of the plasma spraying device on the XY axis mechanism, input the determined spray scanning speed parameters, start the powder feeding mechanism and the plasma spraying device at the same time, and the XY axis starts to move and spray according to the predetermined settings.

[0020] Preferably, the method further comprises a step of inspecting the thickness of the catalytic electrode spray coating after the preparation is completed:

[0021] Use the following formula to check whether the spraying thickness reaches the expected setting:

[0022] m=σ A M

[0023] M=l·w·h·ρ

[0024]

[0025] Where: A is the effective area ratio of the porous substrate;

[0026] M is the total mass of spraying, g;

[0027] N is the mesh size (the number of holes per inch of the mesh);

[0028] K is the mesh size in mm;

[0029] L is a constant of 25.4 mm;

[0030] l is the length of substrate in mm;

[0031] w is the substrate width in mm;

[0032] h is the coating thickness in mm;

[0033] ρ is the alloy density g / mm 3 ;

[0034] m is the theoretical weight gain of the substrate after spraying according to the set spraying thickness;

[0035] By comparing the theoretical weight gain of the substrate with the actual weight gain of the substrate, it is possible to check whether the coating thickness meets the requirements.

[0036] The beneficial technical effects of the present invention are:

[0037] (1) The preparation method of the present invention determines the optimal spraying thickness based on the relationship between the spraying thickness and the electrode performance, and uses the formula established in the method steps to quickly obtain the corresponding spraying scanning speed for parameter setting to complete plasma spraying, without the need to repeatedly perform spraying tests to determine the operating process.

[0038] (2) The method of the present invention can also be used to conveniently and accurately check whether the process operation has achieved the expected spraying thickness, ensure electrode performance, and improve product quality.

[0039] (3) The catalytic electrode for hydrogen production by water electrolysis prepared by the present invention has good stability and coating reproducibility, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The HER performance test results of the catalytic electrode for hydrogen production by electrolysis of water and the pure nickel mesh prepared in Examples 1 and 2 of the present invention are shown;

[0041] Figure 2 The 12h constant current stability test results of the catalytic electrode for hydrogen production by electrolysis of water and the pure nickel mesh prepared in Examples 1 and 2 of the present invention are shown. DETAILED DESCRIPTION

[0042] The present invention provides a method for preparing a catalytic electrode for producing hydrogen by alkaline water electrolysis at normal pressure, so as to solve the problems in the preparation process of the catalytic electrode for water electrolysis, thereby promoting the industrial application of the technology for producing hydrogen by alkaline water electrolysis.

[0043] The scanning speed of the spray gun during the plasma spraying electrode process satisfies the following relationship:

[0044]

[0045] Among them, v 送 is the powder feeding speed g / s;

[0046] ρ is the alloy density g / mm 3 ;

[0047] h is the coating thickness in mm;

[0048] d is the diameter of the coating sprayed onto the substrate, mm;

[0049] v 扫 is the spray scanning speed mm / s;

[0050] m1 is the mass of material 1 (g), m2 is the mass of material 2 (g), n is the mass of material n (g);

[0051] ρ1 is the density of material 1 (g / mm 3 ), ρ2 is the density of material 2 (g / mm 3 ), ρ n is the density of material n (g / mm 3 ).

[0052] In the process of spraying catalyst, the scanning speed of the spray gun is an important parameter, which includes powder feeding speed, alloy density, spray thickness, nozzle outlet area, etc. The powder feeding speed is generally 50-200g / min. The spray thickness will affect the physical properties of the coating, and then affect the electrode performance. By controlling the scanning speed of the spray gun, the coating weight can be accurately controlled and the optimal spray thickness can be achieved, so that the catalyst performance sprayed on the electrode surface can be optimized. In the actual operation process, the optimal spray thickness is determined according to the relationship between the spray thickness and the electrode performance; combined with the substrate density and quality parameters, and a fixed powder feeding speed is set. Using the above formula, the spray scanning speed can be quickly obtained for parameter setting to complete plasma spraying, without the need for repeated spray tests to determine the operating process.

[0053] The invention provides a method for preparing a catalytic electrode for producing hydrogen by alkaline water electrolysis at normal pressure, which specifically includes the following steps: preparing a catalyst coating and forming an electrode by plasma spraying.

[0054] Preparation of catalyst coating:

[0055] Mix two or more metals in proportion, melt and mix them in a high-frequency furnace, and after cooling, put them into a crusher and crush them into powder.

[0056] Plasma spray electrode forming:

[0057] Place the substrate on the spraying tool and fix it, put the catalyst into the barrel of the powder feeding mechanism, and set the powder feeding speed, usually 50-200g / min. The plasma gun is fixed on the XY axis mechanism, the plasma spraying current is set according to the substrate material, the spraying distance is set according to the diameter of the nozzle, and the scanning speed of the spray gun is calculated using the above formula in combination with the spraying thickness and the set powder feeding speed. Start the powder feeding mechanism and plasma spraying device at the same time, and the XY axis starts to move and spray according to the predetermined settings. Remove the sprayed electrode and weigh it to check the spraying thickness.

[0058] After preparation, the following formula can be used to check whether the spraying thickness reaches the expected setting:

[0059] m=σ A M

[0060] M=l·w·h·ρ

[0061]

[0062] Where: A is the effective area ratio of the porous substrate;

[0063] M is the total mass of spraying (g);

[0064] N is the mesh size;

[0065] K is the mesh size (mm);

[0066] L is a constant of 25.4 mm;

[0067] l is the length of the substrate (mm);

[0068] w is the substrate width (mm);

[0069] h is the coating thickness (mm);

[0070] ρ is the alloy density (g / mm 3 );

[0071] m is the theoretical weight gain of the substrate after spraying according to the set spray thickness (g); comparing it with the actual weight gain of the substrate can check whether the coating thickness meets the standard.

[0072] The present invention will be further described below in conjunction with specific embodiments:

[0073] Example 1

[0074] Preparation of catalyst coating powder:

[0075] Metal nickel, metal aluminum and metal iron are mixed in a ratio of 60%, 10% and 30% respectively, and the total mass after mixing is 2000g. They are melted and mixed in a high frequency furnace, and after cooling, they are put into a pulverizer and crushed into powder to make catalyst coating powder.

[0076] According to the formula The calculated density of the catalyst coating powder is 7.0124 g / cm 3 .

[0077] Plasma spray electrode forming:

[0078] Place the 1x2m nickel mesh on the spraying tool and fix it, put the catalyst coating powder into the material bucket of the powder feeding mechanism, and set the powder feeding speed to 60g / min. Fix the plasma gun on the XY axis mechanism, set the plasma spraying current and the coating diameter d (15mm) sprayed on the substrate, combined with the spraying thickness h (30μm), and use the formula The scanning speed of the spray gun is calculated and the result is 316.8 mm / s. The scanning speed parameters are set, and the powder feeding mechanism and plasma spraying device are started at the same time, and the XY axis starts to move and spray according to the predetermined settings.

[0079] Remove the sprayed electrode, the nickel mesh number is 50, the mesh size is 0.3mm, and the formula is used The effective area ratio of the substrate is calculated to be 0.651. Using M = l·w·h·ρ, the total mass of the spraying is 420.744g. Finally, according to m = σ AM is calculated based on the above parameter settings. After spraying, the theoretical weight increase of the nickel mesh is 273.9g, and the actual weight increase of the nickel mesh is 269.2g, which meets expectations.

[0080] Example 2

[0081] Preparation of catalyst coating powder:

[0082] 3000g of metal nickel, metal molybdenum and metal iron are mixed in proportions of 70%, 10% and 20% respectively, melted and mixed in a high-frequency furnace, and after cooling, put into a pulverizer to be crushed into powder to make catalyst coating powder.

[0083] According to the formula The calculated density of the catalyst coating powder is 8.781 g / cm 3 .

[0084] Plasma spray electrode forming:

[0085] Place the 1x2m nickel mesh on the spraying tool and fix it, put the catalyst coating powder into the material bucket of the powder feeding mechanism, and set the powder feeding speed to 50g / min. Fix the plasma gun on the XY axis mechanism, set the plasma spraying current and the spraying diameter d (12mm) sprayed on the substrate, combined with the spraying thickness h (20μm), use the formula The scanning speed of the spray gun is calculated and the result is 395.4 mm / s. The scanning speed parameters are set, and the powder feeding mechanism and plasma spraying device are started at the same time, and the XY axis starts to move and spray according to the predetermined settings.

[0086] Remove the sprayed electrode, the nickel mesh number is 50, the mesh size is 0.3mm, and the formula is used The effective area ratio of the substrate is calculated to be 0.651. Using M = l·w·h·ρ, the total mass of the spray is 351.24g. Finally, according to m = σ A M is calculated based on the above parameter settings. After spraying, the theoretical weight increase of the nickel mesh is 228.6g, and the actual weight increase of the nickel mesh is 225.23g, which meets expectations.

[0087] The performance of the electrodes prepared in Example 1 and Example 2 was tested as follows:

[0088] The electrochemical test was carried out on an electrochemical workstation, using the alkaline water electrolysis alloy electrode prepared in the above embodiment as the cathode, the carbon rod as the counter electrode, and the Hg / HgO electrode as the reference electrode. The linear scanning polarization curve and constant current stability of the hydrogen evolution electrode were measured in 1 mol / L KOH solution. The results are shown in FIG. Figure 1 , Figure 2 shown.

[0089] according to Figure 1 and Figure 2The test results show that the hydrogen evolution end of the catalytic electrode for hydrogen production by electrolysis of water prepared by the present invention has good electrochemical performance and good electrode stability, indicating that the electrode prepared by the method of the present invention has excellent performance.

Claims

1. A method for preparing a catalytic electrode for producing hydrogen by alkaline water electrolysis, characterized in that The following steps are involved: (1) Using plasma spraying technology to prepare catalytic electrodes for hydrogen production by alkaline water electrolysis; (2) Determine the alloy density using the following formula (1); In formula (1), m1 is the mass of material 1 in g, m2 is the mass of material 2 in g, and m n is the mass of material n, g; ρ1 is the density of material 1, g / mm 3 , ρ2 is the density of material 2 g / mm 3 , ρ n is the density of material n g / mm 3 ; (3) Establish the relationship between the spray scanning speed and the coating thickness during the plasma spraying process, as shown in the following formula (2): In formula (2), v 送 is the powder feeding speed g / s, ρ is the alloy density g / mm 3 , h is the coating thickness (mm), d is the coating diameter sprayed onto the substrate (mm), v 扫 is the spray scanning speed mm / s; (4) Determine the optimal spraying thickness based on the relationship between the spraying thickness and the electrode performance; then calculate the spraying scanning speed through step (3), and set the parameters according to the obtained spraying scanning speed value to complete the plasma spraying.

2. The method for preparing a catalytic electrode for producing hydrogen by alkaline water electrolysis according to claim 1, characterized in that: Step (2) also includes the step of preparing the catalyst coating powder: Mix two or more metals in proportion, melt and mix them in a high-frequency furnace, and after cooling, put them into a pulverizer to crush them into powder to obtain catalyst coating powder.

3. The method for preparing a catalytic electrode for producing hydrogen by alkaline water electrolysis according to claim 1, characterized in that: In step (3): the powder feeding speed is selected to be 10-200 g / min.

4. The method for preparing a catalytic electrode for producing hydrogen by alkaline water electrolysis according to claim 1, characterized in that: Step (4) also includes the following steps: Place the substrate to be sprayed on the spraying tooling and fix it, put the catalyst coating powder into the material barrel of the powder feeding mechanism, and set the powder feeding speed; fix the plasma gun of the plasma spraying device on the XY axis mechanism, input the determined spray scanning speed parameters, start the powder feeding mechanism and the plasma spraying device at the same time, and the XY axis starts to move and spray according to the predetermined settings.

5. The method for preparing a catalytic electrode for producing hydrogen by alkaline water electrolysis according to claim 1, characterized in that: It also includes the following steps to inspect the thickness of the catalytic electrode spray after preparation: Use the following formula to check whether the spraying thickness reaches the expected setting: m=σ A M M=l·w·h·ρ Where: A is the effective area ratio of the porous substrate; M is the total mass of spraying, g; N is the mesh size; K is the mesh size in mm; L is a constant of 25.4 mm; l is the length of substrate in mm; w is the substrate width in mm; h is the coating thickness in mm; ρ is the alloy density g / mm 3 ; m is the theoretical weight gain of the substrate after spraying according to the set spraying thickness; By comparing the theoretical weight gain of the substrate with the actual weight gain of the substrate, it is possible to check whether the coating thickness meets the standard.

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