Alkaline water electrolysis hydrogen production self-supporting catalytic electrode and preparation method thereof

Abstract

The invention discloses a self-supporting catalytic electrode for hydrogen production from alkaline electrolyzed water and a preparation method of the self-supporting catalytic electrode. The preparation method comprises the steps that an electroplating solution containing nickel salt, ferric salt and ammonium chloride is prepared, then in the electroplating solution, a conductive substrate serves as a cathode, metal nickel serves as an anode, an external power source is used for providing gradually-increased electroplating voltage, and electroplating is carried out in three stages; depositing a nickel-iron alloy conducting layer on the cathode in an electroplating voltage range of 0.5-1.0 V; the electroplating voltage is gradually increased to 1.0-1.4 V, and a transition layer in which the ferro-nickel alloy and LDH coexist continues to be deposited on the cathode; and the electroplating voltage is further increased to 1.4-1.8 V, and the LDH active layer continues to be deposited on the cathode. The conductive supporting layer and the high-activity catalytic layer are continuously deposited on the same substrate through the electroplating technology, integrated combination of conductivity and catalytic performance is achieved, and the defects that in a traditional catalytic electrode, the binding force between an active layer and a supporting body is weak, and stability is poor are overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic electrodes for producing hydrogen by electrolysis of water, and more specifically, to a self-supporting catalytic electrode for producing hydrogen by electrolysis of water using alkaline method and a preparation method thereof. Background Art

[0002] As the global energy crisis and environmental issues become increasingly prominent, hydrogen energy has attracted widespread attention as a clean and efficient renewable energy source. Water electrolysis hydrogen production technology has become an important means to achieve large-scale production of hydrogen energy due to its advantages of zero carbon emissions and high-purity hydrogen. However, the widespread application of this technology still faces the challenges of high energy consumption and insufficient stability of electrode catalysts. Therefore, the development of highly active and highly stable electrode materials is of great significance to improving the efficiency of water electrolysis hydrogen production.

[0003] In the water electrolysis system, the catalytic performance of the electrode material directly affects the rate of hydrogen and oxygen evolution reactions, while the conductivity and structural stability of the electrode determine its service life. At present, non-precious metal-based catalysts have attracted widespread attention from researchers due to their low cost and high activity. Among them, layered double hydroxides (LDH), as a highly active non-precious metal catalyst, show great application potential due to its rich and adjustable composition, layered structure and excellent electrochemical performance. However, LDH itself has poor conductivity and needs to be combined with a conductive matrix to fully exert its catalytic activity. In traditional methods, LDH is usually attached to the surface of a conductive matrix by hydrothermal, coprecipitation or electrodeposition. This method easily leads to weak bonding between the active layer and the matrix. During long-term electrolysis, due to stress and corrosion, the active layer is easily peeled off or falls off, resulting in a rapid decline in electrode performance.

[0004] In recent years, electroplating technology has gradually attracted the attention of researchers due to its advantages of simple operation, strong controllability, low cost and suitability for large-scale preparation. However, there is no method to prepare an integrated composite catalytic electrode of a conductive support and LDH in one step using electroplating technology to improve its bonding strength and electrochemical stability. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention proposes a self-supporting catalytic electrode for hydrogen production by alkaline water electrolysis and a preparation method thereof. A conductive support layer and a high-activity catalytic layer are continuously deposited on the same substrate through electroplating technology to achieve an integrated combination of conductivity and catalytic performance, thereby overcoming the defects of weak bonding between the active layer and the support body and poor stability in traditional catalytic electrodes.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing a self-supporting catalytic electrode for hydrogen production by alkaline water electrolysis, comprising the following steps:

[0007] Step S1, cutting the conductive substrate into a desired size, and cleaning and drying it to remove surface oxides and contaminants; preparing an electroplating solution containing nickel salt, iron salt and ammonium chloride, wherein:

[0008] Nickel ions come from nickel chloride, with a concentration of 0.01~1.0 M;

[0009] The iron ions come from ferrous chloride, with a concentration of 0.01~1.0 M;

[0010] Ammonium chloride was used as a complexing agent and buffer at a concentration of 0.5–4.0 M;

[0011] The solution pH was adjusted to 3.0-6.0;

[0012] Step S2, electroplating process control: in the electroplating solution, with the conductive substrate as the cathode and the metal nickel as the anode, the electroplating voltage is gradually increased by an external power supply, and the electroplating is carried out in three stages;

[0013] The first stage (0-2 min): In the electroplating voltage range of 0.5-1.0 V, a nickel-iron alloy conductive layer is first deposited on the cathode;

[0014] The second stage (2-3 min): the electroplating voltage is gradually increased to 1.0-1.4 V, and the transition layer of nickel-iron alloy and LDH coexisting continues to be deposited on the cathode;

[0015] The third stage (3-5 min): the electroplating voltage is further increased to 1.4-1.8 V, and the LDH active layer continues to be deposited on the cathode;

[0016] Step S3, post-treatment: clean the electroplated cathode with deionized water and dry it.

[0017] The above preparation method adopts a one-step electroplating method. By gradually adjusting the electroplating voltage and time, a three-layer structure is formed on the surface of the substrate: a conductive support layer, a transition layer and an LDH catalytic active layer. This improves the bonding strength and stability between the active layer and the support in the catalytic electrode. The method is simple to operate, low in cost and suitable for large-scale production. It is suitable as a core electrode material in electrochemical devices such as water electrolysis for hydrogen production and supercapacitors.

[0018] Furthermore, the conductive substrate is a nickel mesh, nickel foam or other metal conductive substrate.

[0019] Furthermore, in the step S1, the cleaning of the conductive substrate includes acid washing, water washing and alcohol washing in sequence.

[0020] Furthermore, in the electroplating solution, The concentration is 0.1 M; The concentration of is 0.05 M; the concentration of ammonium chloride is 1.0 M; and the pH value of the electroplating solution is adjusted to 4 with ammonia water.

[0021] Furthermore, in step S2, the anode is a nickel plate.

[0022] Furthermore, in the step S2, the first stage 1 of electroplating (0-2 minutes): applying a voltage of 0.8 V to form a nickel-iron alloy conductive layer; the second stage (2-3 minutes): the voltage gradually transitions from 0.8 V to 1.6 V to form a transition layer in which the nickel-iron alloy and LDH coexist; the third stage (3-5 minutes): raising the voltage to 1.6 V to deposit an LDH active layer.

[0023] In a second aspect, the present invention provides a self-supporting catalytic electrode for hydrogen production by alkaline water electrolysis, which is prepared by the preparation method as described above, and includes a conductive substrate and a nickel-iron alloy conductive layer distributed from the inside to the outside on the surface of the conductive substrate, a transition layer in which the nickel-iron alloy and LDH coexist, and an LDH active layer.

[0024] Compared with the prior art, the present invention adopts the electroplating method to prepare the self-supporting catalytic electrode in one step, which has the significant advantages of stable structure, low cost, simple process and excellent performance.

[0025] First, by gradually adjusting the electroplating voltage and time, a conductive support layer, a transition layer and an LDH catalyst layer are continuously formed on the surface of the substrate, realizing the integrated combination of conductivity and catalytic performance, effectively avoiding the problems of weak bonding and easy detachment between the active layer and the substrate in the traditional layered attachment process, and greatly improving the mechanical strength and durability of the electrode.

[0026] Secondly, this method utilizes an electroplating process to directly deposit materials on the substrate surface, avoiding complex precursor synthesis and post-processing steps, reducing equipment and material costs, and is suitable for large-scale industrial production.

[0027] Thirdly, the LDH layer on the electrode surface has abundant catalytic active sites and excellent redox properties, exhibiting low overpotential and high current density in the process of hydrogen production by water electrolysis, significantly improving the hydrogen production efficiency.

[0028] The method is environmentally friendly, uses a water-based electroplating solution, does not require high-temperature calcination and organic solvent treatment, and further reduces the risk of environmental pollution. In summary, the present invention provides a high-efficiency catalytic electrode with a simple preparation process, low cost and stable performance, which meets the urgent demand of the hydrogen energy industry for high-performance electrode materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 FIG. 4 is a curve showing the change of voltage applied during electroplating over time in one embodiment of the present invention.

[0030] Figure 2 The following are SEM photos of the electrode surface microstructure at various stages of electroplating in one embodiment of the present invention.

[0031] Figure 3 This is a cathode bonding strength test curve after electroplating in one embodiment of the present invention.

[0032] Figure 4 1 is a performance curve of electrode oxygen evolution reaction in one embodiment of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0034] The execution order of actions, steps, etc. in the devices and methods shown in the claims, specifications and drawings can be implemented in any order as long as there is no special explicit limitation on the order and the output of the previous processing is not used in the subsequent processing.

[0035] The reaction devices, compounds and solvents involved in the following embodiments and examples are all commercially available. The detection instruments and detection reagents involved in the following effect embodiments are all commercially available, and the detection methods used are the prior art that can be retrieved.

[0036] Example

[0037] See also Figure 1 This embodiment provides a method for preparing a self-supporting catalytic electrode for hydrogen production by alkaline water electrolysis, using a nickel mesh or other conductive substrate as a starting substrate, and completing the electrode preparation process in one step by reasonably designing the composition of the electroplating solution and the process parameters, which specifically includes the following steps:

[0038] (1) Substrate treatment

[0039] The nickel mesh or other conductive substrate is cut into the required size, cleaned and dried, preferably acid-washed, water-washed and alcohol-washed in sequence to remove surface oxides and contaminants, ensure the cleanliness of the electrode surface and improve the electroplating bonding strength.

[0040] (2) Preparation of electroplating solution

[0041] A plating solution is prepared containing a nickel salt, an iron salt and ammonium chloride, wherein:

[0042] Nickel ions come from nickel chloride , concentration is 0.05~0.30 M;

[0043] Iron ions come from ferrous chloride , concentration is 0.01~0.05 M;

[0044] Ammonium chloride As a complexing agent and buffer, the concentration is 0.5~4.0 M;

[0045] The concentration ratio of nickel ions to iron ions is 1.5-2.5:1; if the nickel ion concentration is too high, the obtained product lacks active surface area, and if it is too low, the obtained product has poor firmness; if the iron ion concentration is too high, the obtained product has poor firmness, and if it is too low, the obtained product has low catalytic activity; if the ammonium chloride concentration is too high, the obtained product cannot prepare LDH, and if it is too low, the obtained product has poor firmness.

[0046] The solution pH was adjusted to 3.0~6.0 to ensure the stability of the deposition process.

[0047] (3) Electroplating process control

[0048] In the electroplating solution, the conductive substrate is used as the cathode and the metal nickel is used as the anode. The electroplating voltage is applied by an external power supply. When the concentration of various raw materials is within the above range, electroplating is completed in three stages:

[0049] Stage 1: Conductive layer deposition (0~2 min)

[0050] In the voltage range of 0.5~1.0 V, a nickel-iron alloy conductive layer is mainly deposited on the cathode surface, providing high conductivity and mechanical strength.

[0051] The second stage: transition layer deposition (2~3 min)

[0052] The voltage was gradually increased to 1.0-1.4 V, and a transition layer where nickel-iron alloy and LDH coexisted continued to form on the cathode surface to enhance the binding force.

[0053] The third stage: LDH active layer deposition (3~5 min)

[0054] When the voltage further increased to 1.4-1.8 V, a pure LDH catalytic active layer continued to be deposited on the cathode surface, giving the electrode excellent catalytic performance.

[0055] (4) Post-processing

[0056] After electroplating, the electrodes were rinsed with deionized water and allowed to dry naturally.

[0057] The implementation process of the present invention is described below with a typical example.

[0058] 1. Electrode pretreatment

[0059] (1) Material preparation: A 30 cm² nickel mesh (pore size 80 mesh) was selected as the conductive base material.

[0060] (2) Cleaning process: Treat the substrate in the following solutions in sequence:

[0061] Soak in 1 M hydrochloric acid (HCl) for 10 min to remove the oxide layer;

[0062] Ultrasonic cleaning with deionized water for 5 min to remove acid residues;

[0063] Wash with anhydrous ethanol for 5 minutes to remove organic pollutants.

[0064] (3) Drying step: Blow dry with nitrogen or place in an oven at 60°C.

[0065] 2. Preparation of electroplating solution

[0066] (1) Solution ingredients:

[0067] Nickel chloride : 0.1 M;

[0068] Ferrous chloride : 0.05 M;

[0069] Ammonium chloride : 1.0 M;

[0070] (2) Solution adjustment: Adjust the pH to 4 with aqueous ammonia and stir evenly at room temperature.

[0071] 3. Electroplating process and parameter setting

[0072] (1) Electroplating equipment: nickel mesh is cathode and nickel plate is anode.

[0073] (2) Participate Figure 1 , electroplating steps:

[0074] Stage 1 (0-2 minutes): A voltage of 0.8 V is applied, and a nickel-iron alloy conductive support layer is formed on the surface of the nickel mesh;

[0075] Stage 2 (2-3 minutes): The voltage gradually transitions from 0.8 V to 1.6 V, and a mixed layer of nickel-iron alloy and LDH continues to form on the surface of the nickel mesh;

[0076] Stage 3 (3-5 minutes): The voltage was raised to 1.6 V, and the LDH active layer continued to be deposited on the surface of the nickel mesh.

[0077] 4. Post-processing

[0078] The electrodes after electroplating at each stage were rinsed with deionized water and dried naturally.

[0079] join Figure 2After the three stages of electroplating, the cathode surface forms products with different microstructures. In the first stage of electroplating, a metal base film composed of nanoparticles is formed on the cathode surface. In the second stage of electroplating, a smooth transition layer without obvious particles is covered on the cathode surface. In the third stage of electroplating, a LDH layer composed of self-supporting nanosheets is formed on the cathode surface. The cathode after electroplating consists of a three-layer structure: the innermost layer is a metal base layer, which provides good support and conductivity; the middle layer is a transition layer, which is used to firmly connect the LDH layer and the metal base layer; the outermost layer is an LDH layer, which provides high catalytic activity. Figure 3 The cathode obtained in this example was tested for bonding strength using a universal testing machine, proving that the electrode has a high bonding strength.

[0080] As some parallel experiments, we adjusted the electroplating solution within the raw material concentration range described in the embodiments, and combined with appropriate applied voltage and voltage change pattern during the electroplating stage, we can obtain some parallel samples with structures and compositions similar to the above examples.

[0081] 5. Performance Testing

[0082] Test conditions: In 1 M KOH electrolyte, a three-electrode test system was used to measure the oxygen evolution reaction performance of the cathode after electroplating.

[0083] result:

[0084] See also Figure 4 , the overpotential of the plated cathode in this example at a current density of 100 mA / cm² is only 270 mV, while the overpotential of the unplated nickel mesh at a current density of 100 mA / cm² is 370 mV.

[0085] In addition, in this example, the overpotential change of the cathode after electroplating was less than 5 mV after 100 hours of continuous operation, indicating excellent electrode stability.

[0086] In summary, the present invention provides a self-supporting catalytic electrode for hydrogen production by alkaline water electrolysis prepared in one step by electroplating, which has the significant advantages of stable structure, low cost, simple process and excellent performance.

[0087] Those skilled in the art should understand that those skilled in the art can implement variations by combining the prior art and the above embodiments, which will not be described in detail here. Such variations do not affect the essential content of the present invention, and will not be described in detail here.

[0088] The preferred embodiments of the present invention are described above. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and the systems and structures that are not described in detail should be understood to be implemented in a common manner in the art; any technician familiar with the art can use the above-disclosed methods and technical contents to make many possible changes and modifications to the technical solutions of the present invention without departing from the scope of the technical solutions of the present invention, or modify them into equivalent embodiments of equivalent changes, which does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention are still within the scope of protection of the technical solutions of the present invention.

Claims

1. A method for preparing a self-supporting catalytic electrode for hydrogen production by alkaline water electrolysis, characterized in that: The following steps are involved: Step S1, cutting the conductive substrate into a desired size, and cleaning and drying it to remove surface oxides and contaminants; preparing an electroplating solution containing nickel salt, iron salt and ammonium chloride, wherein: Nickel ions come from nickel chloride, with a concentration of 0.05~0.3 M; The iron ions come from ferrous chloride, with a concentration of 0.01~0.05 M; Ammonium chloride was used as a complexing agent and buffer at a concentration of 0.5–4.0 M; The solution pH was adjusted to 3.0-6.0; The concentration ratio of nickel ions to iron ions is 1.5-2.5:1; Step S2, electroplating process control: in the electroplating solution, with the conductive substrate as the cathode and the metal nickel as the anode, the electroplating voltage is gradually increased by an external power supply, and the electroplating is carried out in three stages; The first stage (0-2 min): In the electroplating voltage range of 0.5-1.0 V, a nickel-iron alloy conductive layer is first deposited on the cathode; The second stage (2-3 min): the electroplating voltage is gradually increased to 1.0-1.4 V, and the transition layer of nickel-iron alloy and LDH coexisting continues to be deposited on the cathode; The third stage (3-5 min): the electroplating voltage is further increased to 1.4-1.8 V, and the LDH active layer continues to be deposited on the cathode; Step S3, post-treatment: clean the electroplated cathode with deionized water and dry it.

2. The method for preparing a self-supporting catalytic electrode for hydrogen production by alkaline water electrolysis according to claim 1, characterized in that: The conductive substrate is a nickel mesh, nickel foam or other metal conductive substrates.

3. The method for preparing a self-supporting catalytic electrode for hydrogen production by alkaline water electrolysis according to claim 1, characterized in that: In the step S1, the cleaning of the conductive substrate includes acid washing, water washing and alcohol washing in sequence.

4. The method for preparing a self-supporting catalytic electrode for hydrogen production by alkaline water electrolysis according to claim 1, characterized in that: In the electroplating solution, The concentration is 0.1 M; The concentration of is 0.05 M; the concentration of ammonium chloride is 1.0 M; and the pH value of the electroplating solution is adjusted to 4 with ammonia water.

5. The method for preparing a self-supporting catalytic electrode for hydrogen production by alkaline water electrolysis according to claim 1 or 4, characterized in that: In step S2, the anode is a nickel plate.

6. The method for preparing a self-supporting catalytic electrode for hydrogen production by alkaline water electrolysis according to claim 1 or 4, characterized in that: In the step S2, the first stage 1 of electroplating (0-2 minutes): applying a voltage of 0.8 V to form a nickel-iron alloy conductive layer; the second stage (2-3 minutes): the voltage gradually transitions from 0.8 V to 1.6 V to form a transition layer in which the nickel-iron alloy and LDH coexist; the third stage (3-5 minutes): raising the voltage to 1.6 V to deposit an LDH active layer.

7. A self-supporting catalytic electrode for hydrogen production by alkaline water electrolysis, characterized in that: The method is prepared by the preparation method according to any one of claims 1 to 6, comprising a conductive substrate and a nickel-iron alloy conductive layer, a transition layer in which the nickel-iron alloy and LDH coexist, and an LDH active layer distributed from the inside to the outside on the surface of the conductive substrate.

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