Electrodeposition nickel-cobalt-based catalyst for hydrogen production by electrolysis of water as well as preparation method and application of electrodeposition nickel-cobalt-based catalyst

Abstract

The preparation method of the electrodeposition nickel-cobalt-based water electrolysis hydrogen production catalyst comprises the steps that a conductive substrate serves as a carrier, nickel salt and cobalt salt are dissolved in deionized water, the constant temperature is kept, nickel-cobalt metal is deposited under the constant current density, and the nickel-cobalt-based water electrolysis hydrogen production catalyst is obtained. And washing to obtain the nickel-cobalt catalyst. The catalyst is prepared by adopting a one-step electrodeposition method, the process is simple and controllable, and raw materials are cheap and easy to obtain; the composition and the structure of the catalyst are optimized by controlling the composition and the temperature of the electroplating liquid, the current density and the time of electro-deposition and pretreatment on the substrate, and the electro-catalytic performance and the stability in the water electrolysis hydrogen evolution process are further improved.

Description

Technical Field

[0001] The present invention belongs to the field of electrocatalytic materials, and in particular relates to an electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst, a preparation method and an application thereof. Background Art

[0002] As a clean and sustainable energy conversion technology, hydrogen production by water electrolysis is an important means of addressing environmental and climate issues caused by traditional carbon-based energy industries. Among existing technical routes, hydrogen production by water electrolysis is mainly divided into three categories: alkaline water electrolysis, proton exchange membrane water electrolysis, and solid oxide water electrolysis. Proton exchange membrane water electrolysis hydrogen production technology relies on high-cost proton exchange membranes and platinum group precious metal catalysts, and requires regular replacement of key components, resulting in high overall production costs; solid oxide water electrolysis hydrogen production has not yet been commercialized due to technical limitations; alkaline water electrolysis technology is the most mature, but it has problems such as low energy conversion efficiency, poor adaptability to high current density, and limitations due to the highly corrosive electrolyte.

[0003] The large-scale application of alkaline water electrolysis to produce hydrogen is still limited by the performance of the catalyst, and it is difficult to achieve stable operation of high current density and efficient hydrogen evolution. Therefore, the development of a low-cost, highly active and stable hydrogen evolution electrocatalyst is crucial to the updating and iteration of the hydrogen production process. Although the current mainstream platinum-based and ruthenium-based precious metal catalysts have excellent performance, the high cost and resource scarcity restrict the industrialization process. Researchers have developed non-precious metal catalysts, among which nickel-based materials are one of the most likely hydrogen evolution reaction (HER) catalysts to replace precious metals, but their performance is still far behind that of precious metal catalysts. How to further optimize the composition and structure of the material to improve its activity and stability has become a difficult problem that needs to be solved urgently, which has important practical significance for the industrial electrolysis of water to produce hydrogen. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide an electrodeposited nickel-cobalt-based catalyst for hydrogen production from water electrolysis, as well as its preparation method and application. This catalyst has the advantages of a rich nanostructure and electronic effects, effectively adsorbing and activating reactants. Furthermore, the nickel-cobalt catalyst firmly bonds to the substrate, further enhancing its excellent stability in strong alkaline environments.

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

[0006] A method for preparing an electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst comprises the following steps: using a conductive substrate as a carrier, dissolving nickel salt and cobalt salt in deionized water, maintaining a constant temperature, depositing nickel and cobalt metals at a constant current density, and washing the mixture to obtain the nickel-cobalt catalyst.

[0007] The method for preparing an electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst comprises the following steps:

[0008] S1: Pre-treating the conductive substrate, including removing surface organic matter by solvent ultrasonic cleaning, washing with deionized water, then acid washing, and finally cleaning with deionized water;

[0009] S2: preparing an electroplating solution containing nickel salt and cobalt salt;

[0010] S3: Using the conductive substrate pretreated in step S1 as a cathode and setting an anode counter electrode, electroplating is performed at a certain temperature in the electroplating solution of step S2. The obtained electrode sheet is washed and dried to obtain a catalyst.

[0011] Furthermore, the pretreatment in step S1 includes solvent ultrasonic cleaning of oil stains, deionized water cleaning, acid cleaning, and deionized water cleaning in sequence; the solvent is selected from one or more of acetone, anhydrous ethanol and isopropanol; the acid cleaning solution is selected from one or more of hydrochloric acid, sulfuric acid, phosphoric acid and oxalic acid.

[0012] Furthermore, in step S1, the mass fraction of the pickling solution is 10% to 50%, the solvent ultrasonic cleaning time is 5 to 30 minutes, and the pickling time is 5 to 30 minutes.

[0013] Furthermore, the pickling solution preferably has a mass fraction of 36% to 38% hydrochloric acid.

[0014] Furthermore, in step S1, the conductive substrate is selected from one of nickel mesh, nickel felt, nickel foam, stainless steel mesh and carbon paper, preferably a nickel mesh with a wire diameter of 0.25 mm and a mesh size of 60.

[0015] Furthermore, in step S3, the anode counter electrode is one of nickel mesh, nickel felt, nickel foam, stainless steel mesh and carbon paper.

[0016] Furthermore, in step S2 , the nickel ion concentration in the electroplating solution is 0.5 to 3 M, and the cobalt ion concentration is 0.01 to 0.5 M. Preferably, the nickel ion concentration is 1 M, and the cobalt ion concentration is 0.1 M.

[0017] Furthermore, in step S2, the nickel salt in the electroplating solution is selected from one or more of nickel chloride, nickel sulfate, nickel acetate, nickel sulfamate and nickel fluoroborate, preferably nickel chloride.

[0018] Furthermore, in step S2, the cobalt salt is selected from one or more of cobalt chloride, cobalt sulfate, cobalt acetate, cobalt sulfamate and nickel fluoroborate, preferably cobalt chloride.

[0019] Furthermore, in step S3, the electrodeposition adopts a two-electrode system, including a working electrode and a counter electrode, and the conductive substrate pretreated in step S1 is used as the working electrode, and the other conductive substrate pretreated in step S1 is used as the counter electrode; during the electrodeposition process, the system temperature is controlled at 10 to 40°C and remains stable; the electrodeposition current density is -50 to -400 mA cm -2 , preferably -100 to -160 mA cm -2 The electrodeposition time is 1-20 min, preferably 4-8 min, and more preferably 5-6 min.

[0020] The present invention also discloses the use of the catalyst in hydrogen production by electrolysis of water. The catalyst is used as a cathode, an anode counter electrode is provided, and a 20% to 35% by mass potassium hydroxide aqueous solution is used as an electrolyte. The water electrolysis reaction is carried out at 60 to 85°C. Preferably, the mass fraction of the potassium hydroxide electrolyte is 30%, and the water electrolysis temperature is 80°C.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1) The present invention provides an electrodeposited nickel-cobalt-based catalyst for hydrogen production from water electrolysis and a preparation method thereof. The preparation method adopts a one-step electrodeposition method, which is simple and controllable, and uses inexpensive and readily available raw materials. By controlling the composition and temperature of the electroplating solution, the current density and time of the electrodeposition, and the pretreatment of the substrate, the composition and structure of the catalyst are optimized, thereby further improving the electrocatalytic performance and stability during the process of hydrogen evolution from water electrolysis.

[0023] 2) The nickel-cobalt catalyst prepared by the present invention is used for hydrogen production by alkaline water electrolysis. The catalyst is firmly bonded to the substrate and has good stability, and has prospects for large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a scanning electron microscope image of the nickel-cobalt catalyst prepared in Example 1 of the present invention;

[0025] Figure 2A This is a comparison chart of the hydrogen evolution performance of the nickel-cobalt catalysts of Examples 1 to 9 used in the present invention;

[0026] Figure 2B This is a comparison chart of hydrogen evolution performance of nickel-cobalt catalysts of Comparative Examples 1 to 5 of the present invention and commercial Raney nickel;

[0027] Figure 3 This is a potential-time curve diagram of the test of Example 1 of the present invention;

[0028] Figure 4 This is a potential-time curve diagram of the test of Example 10 of the present invention. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0030] The nickel mesh used in the embodiment of the present invention has a wire diameter of 0.25 mm and a mesh size of 60. Before use, the nickel mesh has been pretreated: the nickel mesh is placed in a beaker, ultrasonically treated with acetone for 10 minutes, then taken out and rinsed with deionized water, and then immersed in a beaker containing 36% to 38% mass fraction hydrochloric acid for pickling time of 13 minutes, and finally rinsed with deionized water.

[0031] Example 1

[0032] An electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst and a preparation method thereof, comprising the following steps:

[0033] 1) Weigh 30 mmol of nickel chloride hexahydrate and 3.0 mmol of cobalt chloride hexahydrate and dissolve them in 30 mL of deionized water to prepare an electroplating solution. The nickel ion concentration in the electrolyte is 1 M, and the cobalt ion concentration is 0.1 M.

[0034] 2) Take a nickel mesh with a size of 1cm×1cm as the electroplating base material (cathode) and another nickel mesh with a size of 1cm×1cm as the anode, control the temperature of the above-prepared electroplating solution to 20℃, and -2 Electrodeposition was performed for 337.5s at a current density of , and after the electrodeposition was completed, it was rinsed with deionized water to obtain a nickel-cobalt catalyst deposited on the cathode.

[0035] The nickel-cobalt catalyst obtained in Example 1 was characterized by SEM, and the surface morphology was as follows Figure 1 As shown in Figure 2, many nanosheet structures grow on the surface of the nickel-cobalt catalyst, which are intertwined and bonded to each other, are loose and porous, and have a large specific surface area.

[0036] Example 2

[0037] An electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst and a preparation method thereof, comprising the following steps:

[0038] The preparation steps of this embodiment are the same as those of Example 1. The difference from Example 1 is that the amount of cobalt chloride hexahydrate added in step 1) is changed to 0.3 mmol, the cobalt ion concentration in the electrolyte is changed to 0.01 M, and the other process parameters are the same as those of Example 1.

[0039] Example 3

[0040] An electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst and a preparation method thereof, comprising the following steps:

[0041] The preparation steps of this embodiment are the same as those of Example 1. The difference from Example 1 is that the amount of cobalt chloride hexahydrate added in step 1) is changed to 15 mmol, the cobalt ion concentration in the electrolyte is changed to 0.5 M, and the other process parameters are the same as those of Example 1.

[0042] Example 4

[0043] An electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst and a preparation method thereof, comprising the following steps:

[0044] The preparation steps of this embodiment are the same as those of embodiment 1. The difference from embodiment 1 is that the electrodeposition current density and time in step 2) are changed to -120 mA cm -2 and 450s, and the other process parameters are the same as those in Example 1.

[0045] Example 5

[0046] An electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst and a preparation method thereof, comprising the following steps:

[0047] The preparation steps of this embodiment are the same as those of embodiment 1. The difference from embodiment 1 is that the electrodeposition current density and time in step 2) are changed to -200 mA cm -2 and 270s, and other process parameters are the same as those in Example 1.

[0048] Example 6

[0049] An electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst and a preparation method thereof, comprising the following steps:

[0050] The preparation steps of this embodiment are the same as those of Example 1. The difference from Example 1 is that the temperature control temperature of the plating solution in step 2) is changed to 15° C., and the other process parameters are the same as those of Example 1.

[0051] Example 7

[0052] An electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst and a preparation method thereof, comprising the following steps:

[0053] The preparation steps of this embodiment are the same as those of Example 1. The difference from Example 1 is that the temperature control temperature of the plating solution in step 2) is changed to 25° C., and the other process parameters are the same as those of Example 1.

[0054] Example 8

[0055] An electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst and a preparation method thereof, comprising the following steps:

[0056] The preparation steps of this embodiment are the same as those of Example 1. The difference from Example 1 is that the 3.0 mmol of cobalt chloride hexahydrate added in step 1) is replaced with 3.0 mmol of cobalt sulfate heptahydrate, and the cobalt ion concentration in the electrolyte remains unchanged; the 30 mmol of nickel chloride hexahydrate added in step 1) is replaced with 30 mmol of nickel sulfate hexahydrate, and the remaining process parameters are the same as those in Example 1.

[0057] Example 9

[0058] An electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst and a preparation method thereof, comprising the following steps:

[0059] The preparation steps of this embodiment are the same as those of Example 1. The difference from Example 1 is that the conductive base nickel mesh in step 1) is replaced with carbon paper, and the other process parameters are the same as those of Example 1.

[0060] The carbon paper model TGP-H-060 in Example 9 is from Suzhou Shengernuo Technology Co., Ltd.

[0061] Example 10

[0062] An electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst and a preparation method thereof, comprising the following steps:

[0063] The preparation steps of this embodiment are the same as those of Example 1. The difference from Example 1 is that the specifications of the conductive base nickel mesh in step 1) are changed to 5 cm×5 cm, and the other process parameters are the same as those of Example 1 (the volume of the electroplating solution is proportionally increased to 90 mL).

[0064] Comparative Example 1

[0065] An electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst and a preparation method thereof, comprising the following steps:

[0066] The preparation steps of this embodiment are the same as those of embodiment 1. The difference from embodiment 1 is that the electrodeposition current density and time in step 2) are changed to -30 mA cm -2 and 1800s, and other process parameters are the same as those in Example 1.

[0067] Comparative Example 2

[0068] An electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst and a preparation method thereof, comprising the following steps:

[0069] The preparation steps of this embodiment are the same as those of Example 1. The difference from Example 1 is that the amount of cobalt chloride hexahydrate added in step 1) is changed to 0 mmol, the cobalt ion concentration in the electrolyte is changed to 0 M, and the other process parameters are the same as those of Example 1.

[0070] Comparative Example 3

[0071] An electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst and a preparation method thereof, comprising the following steps:

[0072] The preparation steps of this embodiment are the same as those of Example 1. The difference from Example 1 is that the amount of cobalt nickel hexahydrate added in step 1) is changed to 0 mmol, the nickel ion concentration in the electrolyte is changed to 0 M, and the remaining process parameters are the same as those of Example 1.

[0073] Comparative Example 4

[0074] An electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst and a preparation method thereof, comprising the following steps:

[0075] The preparation steps of this embodiment are the same as those of Example 1. The difference from Example 1 is that the 3.0 mmol of cobalt chloride hexahydrate added in step 1) is replaced with 3.0 mmol of ferric chloride hexahydrate, the iron ion concentration in the electrolyte is 0.1 M, and the other process parameters are the same as those of Example 1.

[0076] Comparative Example 5

[0077] An electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst and a preparation method thereof, comprising the following steps:

[0078] The preparation steps of this embodiment are the same as those of Example 1. The difference from Example 1 is that the 3.0 mmol of cobalt chloride hexahydrate added in step 1) is replaced with 3.0 mmol of copper chloride dihydrate, the copper ion concentration in the electrolyte is 0.1 M, and the other process parameters are the same as those of Example 1.

[0079] Application Example 1:

[0080] Commercial Raney nickel electrode sheets were purchased from Hebei Ruiyun Wire Mesh Technology Co., Ltd. with an aperture of 60 mesh.

[0081] The nickel-cobalt catalysts obtained in Examples 1 to 9 and Comparative Examples 1 to 5 and the commercial Raney nickel electrode sheet were used as working electrodes for electrochemical performance testing. The test conditions were as follows: the test temperature was room temperature, and a three-electrode system was used, with the working electrode, the nickel mesh as the counter electrode, the Hg / HgO electrode as the reference electrode, and the electrolyte being a 1 M KOH aqueous solution. The electrolyte impedance was measured at the open circuit voltage, and the overpotential was obtained after chronopotentiometry testing and manual compensation for the ohmic voltage drop.

[0082] According to the above test method, the hydrogen evolution performance of different working electrodes is as follows: Figure 2A and Figure 2B As shown. In 1M KOH, Figure 2A and Figure 2B Specifically, the above catalyst was -2 and 100mAcm -2The overpotential of commercial Raney nickel catalyst at a low current density (10 mA cm -2 The overpotential of Example 1 (57.1 mV) is higher than that of Example 1 (32.4 mV), and the overpotential difference between the two at high current density is even greater (102 mV). The excellent hydrogen evolution performance of the nickel-cobalt catalyst is attributed to its nanosheet structure and electronic effect.

[0083] According to Figure 2, the performance of the catalyst of Example 8 is not as good as that of Example 1. The reason is that when the catalyst of Example 8 was prepared, the anode passivation film barrier metal in the sulfate system was dissolved, and Ni 2+ The concentration continues to decrease, and the metal ratio in the cathode deposition layer is seriously unbalanced; however, when the catalyst in Example 1 is prepared, chloride ions can maintain the dissolution of the anode metal, and the catalyst deposited on this basis has better HER activity.

[0084] The present invention uses a chloride salt system, which has been experimentally verified to be capable of one-step electrodeposition. Chloride ions destroy the anode passivation film during the electrodeposition process and form a soluble complex to maintain metal dissolution.

[0085] Application Example 2:

[0086] The nickel-cobalt catalyst prepared in Example 1 was subjected to electrochemical hydrogen evolution performance test in an H-type electrolytic cell. The test conditions were as follows: the catalyst electrode was used as cathode, nickel mesh was used as counter electrode, 1M KOH aqueous solution was used as electrolyte, and a DC power supply was used at a constant current density (200 mA cm -2 After 10 minutes of electrolysis, the volume of gas released from the cathode was approximately 15.0 ml, and the Faraday efficiency of hydrogen evolution was as high as 99.6%, close to the theoretical limit, indicating that side reactions on the electrocatalyst surface were negligible.

[0087] The Faraday efficiency of hydrogen evolution, FE, is calculated as follows: the theoretical number of moles of H2 produced by electrolysis / the number of moles of gas calculated from the volume of H2 actually collected by electrolysis × 100%.

[0088]

[0089] Q—the amount of charge passing through the electrode;

[0090] z—the number of electrons transferred per H2 molecule, which is 2;

[0091] F—Faraday constant, taken as 96485C mol -1 .

[0092] Application Example 3:

[0093] The nickel-cobalt catalyst obtained in Example 1 was subjected to a stability test in a single-tank electrolytic cell. The results are as follows: Figure 3As shown, specifically: a programmable DC power supply is used, a nickel-cobalt catalyst electrode is used as the cathode, a 30% mass fraction KOH aqueous solution is used as the electrolyte, and the current density is 800 mA cm at 80 °C. -2 The electrochemical hydrogen evolution reaction is carried out under the following conditions. After about 1100 hours, the cell pressure of the nickel-cobalt catalyst of the present invention remains stable without obvious attenuation.

[0094] Application Example 4:

[0095] The nickel-cobalt catalyst obtained in Example 10 was subjected to a stability test in an alkaline electrolytic cell. The results are shown in FIG. Figure 4 Specifically, the electrochemical hydrogen evolution reaction was conducted at 80°C and a current density of 800 mA cm⁻² using a programmable DC power supply, a nickel-cobalt catalyst electrode as the cathode, and a 30 wt.% KOH aqueous solution as the electrolyte. After approximately 2500 minutes, the cell voltage of the nickel-cobalt catalyst remained essentially stable with minimal fluctuations.

[0096] By comparison, it can be seen that the nickel-cobalt catalyst prepared in Example 1 of the present invention has excellent hydrogen evolution reaction activity and long-term stability, and the preparation process is simple; by conducting amplified application research on the electrode and increasing the active electrode area, the hydrogen production can be increased to meet the needs of large-scale hydrogen production, and has a prospect for large-scale application in the field of alkaline water electrolysis hydrogen evolution electrocatalytic materials.

[0097] The contents described in this specification are merely an enumeration of implementation forms of the inventive concept, and the protection scope of the present invention should not be considered as being limited to the specific forms described in the embodiments.

Claims

1. A method for preparing an electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst, characterized in that Using a conductive substrate as a carrier, nickel salt and cobalt salt are dissolved in deionized water, the temperature is maintained constant, nickel and cobalt metals are deposited under a constant current density, and the nickel-cobalt catalyst is obtained by washing it clean.

2. The method for preparing an electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst according to claim 1, characterized in that The following steps are involved: S1: Pre-treating the conductive substrate, including removing surface organic matter by solvent ultrasonic cleaning, washing with deionized water, then acid washing, and finally cleaning with deionized water; S2: preparing an electroplating solution containing nickel salt and cobalt salt; S3: Using the conductive substrate pretreated in step S1 as a cathode and setting an anode counter electrode, electroplating is performed at a certain temperature in the electroplating solution of step S2. The obtained electrode sheet is washed and dried to obtain a catalyst.

3. The method for preparing an electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst according to claim 2, wherein In step S1, the solvent is one or more of acetone, anhydrous ethanol and isopropanol, the pickling solution is one or more of hydrochloric acid, sulfuric acid, phosphoric acid and oxalic acid, the mass fraction of the pickling solution is 10% to 50%, the solvent ultrasonic cleaning time is 5 to 30 minutes, and the pickling time is 5 to 30 minutes.

4. The method for preparing an electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst according to claim 2, wherein In step S1, the conductive substrate is selected from one of nickel mesh, nickel felt, nickel foam, stainless steel mesh and carbon paper; in step S3, the anode counter electrode is one of nickel mesh, nickel felt, nickel foam, stainless steel mesh and carbon paper.

5. The method for preparing an electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst according to claim 2, characterized in that In step S2 , the nickel ion concentration in the electroplating solution is 0.5-3M, and the cobalt ion concentration is 0.01-0.5M.

6. The method for preparing an electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst according to claim 2, characterized in that In step S2, the nickel salt in the electroplating solution is selected from one or more of nickel chloride, nickel sulfate, nickel acetate, nickel sulfamate and nickel fluoroborate, and the cobalt salt is selected from one or more of cobalt chloride, cobalt sulfate, cobalt acetate, cobalt sulfamate and nickel fluoroborate.

7. The method for preparing an electrodeposited nickel-cobalt-based water electrolysis hydrogen production catalyst according to claim 2, characterized in that In step S3, the system temperature is controlled at 10-40°C during the electrodeposition process and remains stable; the electrodeposition current density is -50-400 mA cm -2 , preferably -100 to -160 mA cm -2 , the electrodeposition time is 1-20 min, preferably 4-8 min.

8. A catalyst prepared by the method of any one of claims 1 to 7.

9. Use of the catalyst as claimed in claim 8 in producing hydrogen by electrolysis of water.

10. The use according to claim 9, characterized in that The catalyst is used as a cathode, an anode counter electrode is provided, and a potassium hydroxide aqueous solution with a mass fraction of 20% to 35% is used as an electrolyte to carry out a water electrolysis reaction at 60 to 85°C.

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