Electroplating solution, electrolytic water hydrogen evolution electrode and preparation method of electrolytic water hydrogen evolution electrode

Abstract

The invention provides electroplating liquid, a water electrolysis hydrogen evolution electrode and a preparation method of the water electrolysis hydrogen evolution electrode, and belongs to the technical field of water electrolysis hydrogen production. The electroplating solution provided by the invention is a weakly acidic platinum plating solution, has the advantages of good stability and reusability, and ensures the stability of a plating layer while effectively regulating and controlling the electrode loading capacity in a circulating electroplating manner. According to the preparation method of the water electrolysis hydrogen evolution electrode, the electrochemical stability of the electrode can be effectively improved, the binding force of a plating layer and a substrate is enhanced, the electrochemical surface area is increased, the utilization rate of platinum is increased, the activity is improved, and the performance of the prepared electrode is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production by electrolyzing water, and particularly to an electroplating solution, an electrolytic water hydrogen evolution electrode and a preparation method thereof. Background Art

[0002] The rapid development of society is inseparable from the support of energy. The rapid exploitation and consumption of non-renewable energy not only bring environmental problems that cannot be ignored, but also urgently require the development of renewable energy and fuel substitutes to fill the energy gap. Hydrogen energy has attracted wide attention due to its advantages such as high energy density, high calorific value, and zero emissions. Currently, hydrogen is mainly produced industrially by means such as coal gasification and methane reforming, and carbon dioxide will be produced during hydrogen production by these routes. Hydrogen production by electrolyzing water can be driven by renewable energy such as wind energy and solar energy, with zero carbon emissions and high hydrogen purity, but its cost is relatively high compared with industrial hydrogen production methods.

[0003] The electrode is one of the key materials for electrolyzing water. The noble metal platinum has electrocatalytic activity in both alkaline water electrolysis and proton exchange membrane two commercial electrolysis of water. Although platinum has excellent hydrogen evolution activity, on the one hand, due to the limited reserves of platinum on the earth, its price is high, resulting in a high cost of the electrolytic water hydrogen evolution electrode. On the other hand, traditional platinum electrodes have problems such as low utilization rate of platinum and insufficient long service life of the electrode. Therefore, developing platinum-based catalysts with high activity, long life and low cost is an important direction for the development of electrolyzing water.

[0004] Existing studies have shown that electroplating to prepare a platinum electrode can improve the utilization rate of platinum and thus reduce the cost, and by regulating the electroplating voltage and current density, the morphology and size of platinum nanoparticles can be regulated to regulate their activity, but the stability is poor, and the binding force between the coating and the substrate may be poor, resulting in electrode inactivation as the coating falls off (see Applied Surface Science 2018 Vol. 444 Pages 303-311).

[0005] In the prior art, the coating prepared by an acidic platinum electroplating solution is relatively dense, has good activity and good binding with the substrate. However, when the electrode activity is improved by increasing the coating thickness, cracking is likely to occur, resulting in problems such as poor electrode stability and short life. A large number of platinum nanoparticles are easily generated during the use of the electroplating solution, causing platinum loss. Although electroplating to prepare a platinum electrode can improve the utilization rate of platinum and reduce the cost, it is necessary to overcome problems such as weak binding force between the coating and the substrate, poor electrode stability, and poor electroplating solution stability. It is necessary to develop an electrode with high activity and high stability and an electroplating process with good electroplating solution stability. Summary of the Invention

[0006] The purpose of the present invention is to provide an electroplating solution, an electrolytic water hydrogen evolution electrode and a preparation method thereof, which provide an effective means for preparing excellent electrodes.

[0007] To achieve the above-mentioned invention object, the present invention provides the following technical solutions: The present invention provides an electroplating solution, comprising the following components: A main salt, a conductive salt, a complexing agent, an additive, and high-purity water; The main salt is selected from platinum salts or mixed salts containing platinum salts; The conductive salt is selected from one or more of sulfates, phosphates, hydrogen phosphates, or acetates of alkali metals; The complexing agent is selected from one or more of nitrogen-containing organic acids, aliphatic hydroxy acids, and organic phosphonic acids; The additive includes one or more of a surfactant, a coating fining agent, or a leveling agent.

[0008] In the present invention, the resistivity of the high-purity water ≥ 15 MΩ·cm (25 °C), including but not limited to one or more combinations of ultrapure water (UPW), deionized water (DI water), and reverse osmosis water (RO water).

[0009] In the present invention, the complexing agent includes one or more of nitrogen-containing organic acids, aliphatic hydroxy acids, and organic phosphonic acids, wherein: Nitrogen-containing organic acid: refers to an organic compound that simultaneously contains a nitrogen atom and a carboxylic acid group (-COOH) or a sulfonic acid group (-SO3H) in its molecule; Aliphatic hydroxy acid: refers to a compound that simultaneously contains a hydroxyl group (-OH) and a carboxylic acid group (-COOH) in a straight-chain or branched-chain aliphatic structure, or a sugar alcohol compound that achieves a complexing function through multiple hydroxyl groups; Organic phosphonic acid: refers to an organic compound that contains at least one phosphonic acid group (-PO3H2) and its derivative structure; Preferably, the nitrogen-containing organic acid includes glycine, sulfamic acid, tryptophan, or aspartic acid; The aliphatic hydroxy acid includes sorbitol or erythritol; The organic phosphonic acid includes ethylenediaminetetramethylenephosphonic acid or 1-hydroxyethylidene-1,1-diphosphonic acid.

[0010] Preferably, the platinum salt includes chloroplatinic acid, chloroplatinate, platinum nitrate, platinum sulfate, or platinum organic acid salt; The mixed salt further contains corresponding salts of one or more of noble metals, transition metals, post-transition metals, or rare earth metals. In the present invention, the noble metals include ruthenium (Ru), iridium (Ir), palladium (Pd), rhodium (Rh), or silver (Ag); The transition metal is selected from copper (Cu), cobalt (Co), iron (Fe), nickel (Ni), titanium (Ti), vanadium (V), chromium (Cr), or molybdenum (Mo); The post-transition metal is selected from tin (Sn), indium (In), bismuth (Bi), aluminum (Al), gallium (Ga), or lead (Pb); The rare earth metal includes cerium (Ce), gadolinium (Gd), dysprosium (Dy), europium (Eu), gadolinium (Gd), praseodymium (Pr), or lanthanum (La).

[0011] Preferably, the anionic surfactant includes one or more of sulfate salts, sulfonate salts, phosphate salts, or carboxylate salts, and is preferably selected from at least one of sodium dodecyl sulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), sodium dioctyl sulfosuccinate (AOT), fatty alcohol polyoxyethylene ether phosphate (MAP), and sodium oleate; The plating grain refiner includes one or more of cyclodextrin, sodium saccharin, coumarin, polyvinylpyrrolidone (PVP), 2-mercaptobenzothiazole (MBT), thiourea, or gelatin; The leveling agent includes one or more of propargyl alcohol, benzotriazole (BTA), polyethylene glycol (PEG), alkylphenol polyoxyethylene ether (OP series), or quaternary ammonium salt compounds.

[0012] Preferably, the pH of the electroplating solution is 3.0 to 6.7.

[0013] Preferably, in the electroplating solution, the final concentration of the main salt is 0.001 to 0.1 M; The final concentration of the conductive salt is 0.01 to 0.1 M; The final concentration of the complexing agent is 0.5 to 5 times the final concentration of the main salt; The final concentration of the additive is 0.005 to 0.01 M.

[0014] The present invention also provides an application of the above electroplating solution in the preparation of an electrolytic water hydrogen evolution electrode.

[0015] The present invention also provides a method for preparing an electrolytic water hydrogen evolution electrode, comprising the following steps: Clean and pre-treat the electrode substrate to obtain a pre-treated substrate; Use the pre-treated substrate as the cathode and perform electroplating treatment with the above electroplating solution to obtain a plated cathode; Perform post-treatment on the plated cathode to obtain an electrolytic water hydrogen evolution electrode; The electroplating treatment uses stepped current constant current electroplating. The current density in the first stage is 0 A / m 2 , and the electroplating time range is 4 s to 1 min. The current density in the second stage ranges from 20 to 100 A / m 2 , and the electroplating time range is 1 to 150 s; The post-treatment includes rolling treatment, annealing treatment or hot pressing treatment.

[0016] Preferably, the anode used in the electroplating treatment is a nickel mesh or a stainless steel sheet; The temperature of the electroplating treatment is 80 - 95 °C; The electrode spacing of the electroplating treatment is 2 - 30 cm; The electroplating treatment is accompanied by stirring, and the stirring includes magnetic stirring, cathode vibration or peristaltic pump treatment; The cleaning pretreatment includes successively using ultrasonic treatment with an alkali solution, ultrasonic treatment with high-purity water, ultrasonic treatment with dilute hydrochloric acid, and ultrasonic treatment with high-purity water; The temperature of the annealing treatment is 200 - 600 °C, the time is 30 - 120 min, the heating rate is 3 - 10 °C / min, and the gas atmosphere is air, nitrogen or an inert gas containing 3 - 8% hydrogen; The temperature of the hot pressing treatment is 60 - 180 °C, the pressure is 0.1 - 3 MPa, and the time is 5 s - 3 min.

[0017] The present invention also provides an electrolytic water hydrogen evolution electrode prepared by the above preparation method.

[0018] Advantages of the present invention: The electroplating solution provided by the present invention is a weakly acidic platinum plating solution. Combined with the addition of a specific complexing agent, it can adjust the pH of the electroplating solution while having a certain coordination ability with Pt ions, and regulate the shape of platinum nanoparticles by changing the electroplating precursor, thereby regulating the platinum surface structure, improving the electrode activity, and having a strong anti-reverse current impact ability. The electroplating solution provided by the present invention has good stability and can be reused. While effectively regulating the electrode loading amount by means of cyclic electroplating, the stability of the coating is ensured.

[0019] The preparation method of the electrolytic water hydrogen evolution electrode provided by the present invention can effectively improve the electrochemical stability of the electrode. By adopting stepwise current combined with low current density and medium current density, the low current density is beneficial to the growth of crystal nuclei and enhances the bonding force between the coating and the substrate, and the medium current density is beneficial to increasing the electrochemical surface area, improving the utilization rate of platinum and improving the activity; combined with the post-treatment steps, filling defects by the migration of atoms at high temperature or improving the coating density by physical rolling, eliminating internal defects and enhancing the bonding force between the coating and the substrate, so that the performance of the prepared electrode is significantly improved. Description of the Drawings

[0020] Figure 1 It is a scanning electron microscope (SEM) image of the electrode of Example 1 of the present invention; Figure 2 It is an SEM image of the electrode of Example 2 of the present invention; Figure 3Performance comparison diagram of the electrodes of Embodiments 1 and 2 of the present invention and traditional alkaline electrolyzed water electrodes; Figure 4 Cyclic voltammetry (CV) diagram of the electroplating solution of Embodiment 3 of the present invention; Figure 5 SEM diagram of the electrode of Embodiment 3 of the present invention; Figure 6 Performance comparison diagram of the electrodes of Embodiments 3 and 4 of the present invention and traditional alkaline electrolyzed water electrodes; Figure 7 Long-term constant current electrolysis diagram of the electrode of Embodiment 3 of the present invention in 30 wt% KOH solution; Figure 8 SEM diagram of the electrode of Embodiment 3 of the present invention after long-term constant current electrolysis; Figure 9 SEM diagram of the electrode of Embodiment 4 of the present invention; Figure 10 Long-term constant current electrolysis diagram of the electrode of Embodiment 4 of the present invention in 30 wt% KOH solution; Figure 11 SEM diagram of the electrode of Embodiment 4 of the present invention after long-term constant current electrolysis; Figure 12 SEM diagram of the electrode of Embodiment 5 of the present invention; Figure 13 SEM diagram of the electrode of Embodiment 6 of the present invention; Figure 14 Performance comparison diagram of the electrodes of Embodiments 5 and 6 of the present invention and traditional alkaline electrolyzed water electrodes; Figure 15 SEM diagram of the electrode of Embodiment 5 of the present invention after performance testing; Figure 16 Long-term constant current electrolysis diagram of the electrode of Embodiment 6 of the present invention in 30 wt% KOH solution; Figure 17 SEM diagram of the electrode of Embodiment 6 of the present invention after long-term constant current electrolysis; Figure 18 SEM diagram of the traditional alkaline electrolyzed water electrode after long-term constant current electrolysis. Detailed implementation manner

[0021] The present invention provides an electroplating solution, which includes the following components: main salt, conductive salt, complexing agent, additive and high-purity water; the main salt is selected from platinum salts or mixed salts containing platinum salts; the conductive salt is selected from one or more of sulfates, phosphates, hydrogen phosphates or acetates of alkali metals; the complexing agent is selected from one or more of nitrogen-containing organic acids, aliphatic hydroxy acids and organic phosphonic acids; the additive includes one or more of surfactants, coating refinement agents or leveling agents.

[0022] In the present invention, the resistivity of the high-purity water is ≥ 15 MΩ·cm (25 °C), including but not limited to one or more combinations of ultrapure water (UPW), deionized water (DI water), and reverse osmosis water (RO water).

[0023] In the present invention, the complexing agent includes one or more of nitrogen-containing organic acids, aliphatic hydroxy acids, and organic phosphonic acids. Preferably, the nitrogen-containing organic acid includes glycine, aminosulfonic acid, tryptophan, or aspartic acid; the aliphatic hydroxy acid includes sorbitol or erythritol; the organic phosphonic acid includes ethylenediaminetetramethylenephosphonic acid or 1-hydroxyethylidene-1,1-diphosphonic acid.

[0024] Preferably, the platinum salt includes chloroplatinic acid, chloroplatinate, platinum nitrate, platinum sulfate, or platinum organic acid salt; more preferably, the platinum salt is selected from one or more of chloroplatinic acid (H2PtCl6), potassium chloroplatinate (K2PtCl6), sodium chloroplatinate (Na2PtCl6), ammonium hexachloroplatinate ((NH4)2PtCl6), platinum nitrate (Pt(NO3)2), platinum sulfate (PtSO4), platinum acetate (Pt(CH3COO)2), and platinum oxalate (PtC2O4).

[0025] The mixed salt also contains corresponding salts of one or several of noble metals, transition metals, post-transition metals, or rare earth metals. In the present invention, the noble metals include ruthenium (Ru), iridium (Ir), palladium (Pd), rhodium (Rh), or silver (Ag); the transition metals are selected from copper (Cu), cobalt (Co), iron (Fe), nickel (Ni), titanium (Ti), vanadium (V), chromium (Cr), or molybdenum (Mo); the post-transition metals are selected from tin (Sn), indium (In), bismuth (Bi), aluminum (Al), gallium (Ga), or lead (Pb); the rare earth metals include cerium (Ce), gadolinium (Gd), dysprosium (Dy), europium (Eu), gadolinium (Gd), praseodymium (Pr), or lanthanum (La).

[0026] Preferably, the anionic surfactant includes one or more of sulfate salts, sulfonate salts, phosphate salts, or carboxylate salts, preferably selected from at least one of sodium dodecyl sulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), sodium dioctyl sulfosuccinate (AOT), fatty alcohol polyoxyethylene ether phosphate (MAP), and sodium oleate; the plating grain refiner includes one or more of cyclodextrin, sodium saccharin, coumarin, polyvinylpyrrolidone (PVP), 2-mercaptobenzothiazole (MBT), thiourea, or gelatin; the leveling agent includes one or more of propargyl alcohol, benzotriazole (BTA), polyethylene glycol (PEG), alkylphenol polyoxyethylene ether (OP series), or quaternary ammonium salt compounds.

[0027] In the present invention, preferably, the pH of the electroplating solution is 3.0 to 6.7; more preferably, the pH of the electroplating solution is 6.0 to 6.7; in the electroplating solution, the final concentration of the main salt is 0.001 to 0.1 M; more preferably, the final concentration of the main salt is 0.005 to 0.05 M; the final concentration of the conductive salt is 0.01 to 0.1 M; more preferably, the final concentration of the conductive salt is 0.03 to 0.07 M; the final concentration of the complexing agent is 0.5 to 5 times the final concentration of the main salt; more preferably, the final concentration of the complexing agent is 1 to 3 times; the final concentration of the additive is 0.005 to 0.01 M; more preferably, the final concentration of the additive is 0.006 to 0.008 M; The present invention also provides the application of the above electroplating solution in the preparation of an electrolytic water hydrogen evolution electrode.

[0028] The present invention also provides a method for preparing an electrolytic water hydrogen evolution electrode, comprising the following steps: Clean and pre-treat the electrode substrate to obtain the pre-treated substrate; Use the pre-treated substrate as the cathode and perform electroplating treatment with the above electroplating solution to obtain the electroplated cathode; Post-treat the electroplated cathode to obtain the electrolytic water hydrogen evolution electrode; The post-treatment includes rolling treatment, annealing treatment or hot pressing treatment.

[0029] Preferably, the anode used in the electroplating treatment is a nickel mesh or a stainless steel sheet; the electroplating treatment is accompanied by stirring, and the stirring includes magnetic stirring, cathode vibration or peristaltic pump treatment; the cleaning and pre-treatment includes successively using ultrasonic treatment with an alkali solution, ultrasonic treatment with high-purity water, ultrasonic treatment with dilute hydrochloric acid, and ultrasonic treatment with high-purity water.

[0030] In the present invention, the electroplating treatment adopts stepped current constant current electroplating. The current density in the first stage is 0 A / m², and the electroplating time ranges from 4 s to 1 min; further preferably, the electroplating time in the first stage ranges from 10 to 30 s; the current density in the second stage ranges from 20 to 100 A / m²; further preferably, the current density in the second stage ranges from 40 to 80 A / m²; the electroplating time in the second stage ranges from 1 to 150 s; further preferably, the electroplating time in the second stage ranges from 30 to 90 s; the temperature of the electroplating treatment is 80 to 95 °C; further preferably, the temperature of the electroplating treatment is 85 to 90 °C; the electrode spacing of the electroplating treatment is 2 to 30 cm; further preferably, the electrode spacing is 5 to 15 cm; the temperature of the annealing treatment is 200 to 600 °C; further preferably, the temperature of the annealing treatment is 300 to 500 °C; the time of the annealing treatment is 30 to 120 min; further preferably, the time of the annealing treatment is 60 to 90 min; the heating rate of the annealing treatment is 3 to 10 °C / min; further preferably, the heating rate is 5 to 8 °C / min; the volume fraction of hydrogen gas in the gas atmosphere of the annealing treatment is 3 to 8%; further preferably, the volume fraction of hydrogen gas is 4 to 6%; the temperature of the hot pressing treatment is 60 to 180 °C; further preferably, the temperature of the hot pressing treatment is 100 to 150 °C; the pressure of the hot pressing treatment is 0.1 to 3 MPa; further preferably, the pressure is 0.5 to 2 MPa; the time of the hot pressing treatment is 5 s to 3 min; further preferably, the time is 30 to 120 s; The present invention also provides an electrolytic water hydrogen evolution electrode prepared by the above preparation method.

[0031] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they cannot be construed as limiting the protection scope of the present invention.

[0032] The method for preparing an electrolytic water hydrogen evolution electrode with a weakly acidic plating solution in the present invention has the following specific process flow: 1. Prepare the electroplating solution.

[0033] 2. Pretreat the substrate: First, ultrasonically degrease and clean the nickel mesh with an alkaline solution for 10 - 20 min, and the temperature ranges from 30 to 40 °C. Then ultrasonically clean with ultrapure water for 10 - 20 min, and the temperature ranges from 30 to 50 °C. Next, ultrasonically treat with dilute hydrochloric acid (1 M) for 10 - 20 min to remove surface oxides and rust, and the temperature ranges from 20 to 30 °C. Then ultrasonically clean the nickel mesh with ultrapure water for a second time for 10 - 20 min, and the temperature ranges from 30 to 50 °C. Finally, dry the nickel mesh with nitrogen and set it aside; 3. Electroplate the pretreated substrate: Use a nickel mesh or stainless steel sheet as the anode, and the substrate pretreated in step 1 as the cathode. The electroplating temperature is 80 - 95 °C. The distance between the anode and cathode is 2 - 30 cm. Select a stirring method according to the size of the substrate and the electroplating bath, such as magnetic stirring, cathode vibration, or continuous circulation of the electroplating solution by a peristaltic pump to improve the mass transfer rate of the liquid phase, reduce the concentration difference, and promote the detachment of bubbles on the electrode surface.

[0034] Adopt stepped current constant current electroplating. The current density in the first stage is 0 A / m 2 , the electroplating time range is 4 s - 1 min, and the current density range in the second stage is 20 - 100 A / m 2 , and the electroplating time range is 1 - 150 s.

[0035] 4. Post - process the electrode: First, rinse the electroplated cathode with water to wash away the residual electroplating solution; then dry it with nitrogen and perform post - treatment using any one of the following methods: 1) Rolling treatment; 2) Annealing treatment, annealing at 200 - 600 °C for 30 - 120 min, with a heating rate of 3 - 10 °C / min, and the gas atmosphere is air, nitrogen, or 5% hydrogen; 3) Hot pressing treatment, hot pressing at 60 - 180 °C and 0.1 - 3 MPa for 5 s - 3 min.

[0036] Example 1 The method for preparing an electrolytic water hydrogen evolution electrode using a weakly acidic electroplating solution provided in this example is as follows: 1. Prepare the electroplating solution, and its composition is chloroplatinic acid (0.005 M), sodium sulfate (0.1 M), tryptophan (0.01 M), erythritol (0.01 M), sodium dodecyl sulfate (0.01 M), and the pH of the electroplating solution is 3.2.

[0037] 2. Pretreat the substrate: First, ultrasonically degrease and clean the nickel mesh with an alkaline solution for 15 min at a temperature of 35 °C. Then ultrasonically clean it with ultrapure water for 15 min at a temperature of 40 °C. Next, perform ultrasonic treatment with dilute hydrochloric acid (1 M) for 15 min to remove surface oxides and rust at a temperature of 25 °C. Then ultrasonically clean the nickel mesh with ultrapure water for a second time for 15 min at a temperature range of 40 °C. Finally, dry the nickel mesh with nitrogen for standby; 3. Electroplate the pretreated substrate: Use a nickel mesh or stainless steel sheet as the anode, and the pretreated substrate as the cathode. The electroplating temperature is 95 °C. Adopt stepped current constant current electroplating. The current density in the first stage is 0 A / m 2 , the electroplating time range is 5 s, and the current density range in the second stage is 100 A / m 2 , and the electroplating time range is 1 s. Repeat the first stage and the second stage 52 times. Rinse the electroplated nickel mesh with water and then dry it with nitrogen.

[0038] Example 2 The difference from Example 1 is that after electroplating, the nickel mesh is rinsed with water and dried with nitrogen, and finally annealed at a temperature of 500 °C for an annealing time ranging from 1 h with a heating rate of 5 °C / min.

[0039] Example 3 The substrate is a sandblasted nickel mesh and is pretreated. The difference from the electroplating solution in Example 1 is that the electroplating solution is prepared with the following composition: chloroplatinic acid (0.005 M), sodium sulfate (0.1 M), sorbitol (0.003 M), sodium dodecyl sulfate (0.01 M), and the pH of the electroplating solution is adjusted to 4.3. The electroplating temperature is 95 °C, and stepped current constant current electroplating is used. The current density in the first stage is 0 A / m 2 , and the electroplating time ranges from 10 s. The current density in the second stage ranges from 100 A / m 2 , and the electroplating time ranges from 25 s. After electroplating, the nickel mesh is rinsed with water, then dried with nitrogen, and finally annealed at a temperature of 500 °C for an annealing time ranging from 30 min with a heating rate of 5 °C / min.

[0040] Example 4 The difference from Example 3 is that in step 2, the electroplating solution is prepared with the following composition: chloroplatinic acid (0.005 M), sodium sulfate (0.1 M), sorbitol (0.003 M), sodium dodecyl sulfate (0.01 M), and the pH of the electroplating solution is adjusted to 5.0 with a KOH solution.

[0041] Example 5 The substrate is a sandblasted nickel mesh and is pretreated. The difference from the electroplating solution in Example 1 is that the electroplating solution is prepared with the following composition: chloroplatinic acid (0.005 M), sodium sulfate (0.1 M), sorbitol (0.003 M), sodium dodecyl sulfate (0.01 M), and the pH of the electroplating solution is adjusted to 5.0 with a KOH solution. The electroplating temperature is 95 °C, and stepped current constant current electroplating is used. The current density in the first stage is 0 A / m 2 , and the electroplating time ranges from 132 s. The current density in the second stage ranges from 30 A / m 2 , and the electroplating time ranges from 338 s. After electroplating, the nickel mesh is rinsed with water, then dried with nitrogen, and finally annealed at a temperature of 500 °C for an annealing time ranging from 30 min with a heating rate of 5 °C / min.

[0042] Example 6 The difference from Example 5 is that in step 3, the electroplating temperature is 95 °C, and stepped current constant current electroplating is used. The current density in the first stage is 0 A / m 2, the electroplating time ranges from 10 s, and the current density in the second stage ranges from 30 A / m 2 , the electroplating time ranges from 25 s, and the first and second stages are cycled 20 times.

[0043] Experimental Example Examples 1-6 were tested, and the specific test contents and results are as follows: S1. Overall water splitting voltage analysis A multi-chamber electrolytic cell was used, with the cathode being the electrode prepared in the example, the anode being plain nickel mesh or nickel foam, the diaphragm being a composite diaphragm, and the electrolyte being a 30 wt% KOH solution, and the temperature being 85°C. The test current densities were 2000, 4000, 6000, 8000, 10000 A / m 2 .

[0044] Description of the drawings and morphological features: The scanning electron microscope (SEM) image of the electrode in Example 1 is shown in Figure 1 ; the SEM image of the electrode in Example 2 is shown in Figure 2 ; the SEM image of the electrode in Example 3 is shown in Figure 5 ; the SEM image of the electrode in Example 4 is shown in Figure 9 ; the SEM image of the electrode in Example 5 is shown in Figure 12 ; the SEM image of the electrode in Example 6 is shown in Figure 13 . The performance comparison of each example with the traditional alkaline electrolysis water electrode is shown in Figure 3 , Figure 6 , Figure 14 .

[0045] The results show that the electrode coatings in Examples 1 and 2 are dense on the surface and uniform in thickness. Observing the coating of the electrode in Example 2 at a larger magnification shows that it is denser. The voltages of Examples 1 and 2 at 2000-10000 A / m 2 are lower than those of the traditional alkaline electrolysis water electrode. Example 2 is better than Example 1 at each test current density, indicating that the annealing post-treatment is beneficial for further reducing the voltage of the hydrogen evolution electrode. The substrates of the electrodes in Examples 3 and 4 are sandblasted nickel meshes, with a lower platinum loading in the electroplating, and the electrode surface is relatively rough. The voltages of Examples 3 and 4 at 2000-10000 A / m 2 are lower than those of the traditional alkaline electrolysis water electrode. The voltages of the two examples are not much different at the current densities of 4000 and 6000 A / m 2 . At a low current density of 200 mA / cm 2 , the voltage of Example 4 is lower, and at high current densities of 8000 and 10000 A / m 2The voltage of Example 3 is lower, indicating that the electrode prepared from a weak acid electroplating solution under a high current density has better performance than that prepared from a relatively neutral solution. The substrates of the electrodes in Examples 5 and 6 are sandblasted nickel meshes, with the platinum loading increased by 2-3 times compared to the electrodes in Examples 3 and 4. The surface of the electrode in Example 5 is rough, loose, and peeling occurs, while the surface of the electrode in Example 6 is denser. The voltages of Examples 5 and 6 at 2000-10000 A / m 2 are lower than those of traditional alkaline electrolyzed water electrodes. The voltage of Example 5 is lower than that of Example 6 at each tested current density, indicating that extending the constant current electroplating time in each stage results in better electrode performance than that prepared by cyclic stepped electroplating.

[0046] S2. Overall water splitting stability analysis Using the same test device as in S1, add stainless steel screws or an Fe-Cr-Ni solution with a concentration ratio of (0.01-1.5 mM):(0.003-0.43 mM):(0.003-0.35 mM) to a 30 wt% KOH electrolyte solution, with a temperature of 85 °C and test current densities of 6000, 10000, 15000, 20000 A / m 2 .

[0047] Description of the drawings and stability verification: The cyclic voltammetry (CV) diagram of the electrode in Example 3 is shown in Figure 4 ; the long-term electrolysis voltage decay curve is shown in Figure 7 , and the morphology after electrolysis is shown in Figure 8 ; the stability test results of Example 4 are shown in Figure 10 (time-voltage curve) and Figure 11 (morphology after electrolysis); the SEM diagram of the morphology after electrolysis of the electrode in Example 5 is shown in Figure 15 ; the stability data of Example 6 are shown in Figure 16 (time-voltage curve) and Figure 17 (morphology after electrolysis); the comparison results of the traditional electrode are shown in Figure 18 .

[0048] The results show that the voltage of the electrode in Example 3 decays by 2.7% after electrolysis at 10000 A / m 2 for 60 h, and there is no obvious change on the surface of the coating, indicating that the coating has certain anti-peeling and anti-deposition capabilities. The electrode in Example 4 can operate stably at 10000 A / m 2 for 200 hours, with a voltage decay of -0.4%, and there is no obvious change on the surface of the coating, indicating that a relatively neutral pH of the electroplating solution is beneficial to improving the stability of the electrode. The electrode in Example 6 can operate at 10000 A / m 2It can stably operate for 280 hours, with a voltage attenuation of -0.5%, and there is no obvious change on the surface of the coating. The electrode surface in Example 5 is loose and easy to fall off, indicating that the electrode prepared by cyclic step electroplating has better stability than that prepared by extending the constant current electroplating time in each stage.

[0049] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. An electroplating solution, characterized in that, It includes the following components: Main salt, conductive salt, complexing agent, additive and high-purity water; The main salt is selected from platinum salts or mixed salts containing platinum salts; The conductive salt is selected from one or more of sulfates, phosphates, hydrogen phosphates or acetates of alkali metals; The complexing agent is selected from one or more of nitrogen-containing organic acids, aliphatic hydroxy acids and organic phosphonic acids; The additive includes one or more of a surfactant, a coating fining agent or a leveling agent.

2. The electroplating solution according to claim 1, wherein, The nitrogen-containing organic acid includes glycine, aminosulfonic acid, tryptophan or aspartic acid; The aliphatic hydroxy acid includes sorbitol or erythritol; The organic phosphonic acid includes ethylenediaminetetramethylenephosphonic acid or 1-hydroxyethylidene-1,1-diphosphonic acid.

3. The electroplating solution according to claim 1, wherein, The platinum salt includes chloroplatinic acid, chloroplatinate, platinum nitrate, platinum sulfate or platinum organic acid salt; The mixed salt also contains corresponding salts of one or more of noble metals, transition metals, post-transition metals or rare earth metals. The noble metals include ruthenium, iridium, palladium, rhodium or silver; The transition metal is selected from copper, cobalt, iron, nickel, titanium, vanadium, chromium or molybdenum; The post-transition metal is selected from tin, indium, bismuth, aluminum, gallium or lead; The rare earth metal includes cerium, gadolinium, dysprosium, europium, praseodymium or lanthanum.

4. The electroplating solution according to claim 1, characterized in that, The anionic surfactant includes one or more of sulfate compounds, sulfonate compounds, phosphate compounds or carboxylate compounds; The coating fining agent includes one or more of cyclodextrin, sodium saccharin, coumarin, polyvinylpyrrolidone, 2-mercaptobenzothiazole, thiourea or gelatin; The leveling agent includes one or more of propargyl alcohol, benzotriazole, polyethylene glycol, alkylphenol polyoxyethylene ether or quaternary ammonium salt compounds.

5. The electroplating solution according to claim 1, wherein The pH of the electroplating solution is 3.0 - 6.

7.

6. The electroplating solution according to claim 1, wherein, In the electroplating solution, the final concentration of the main salt is 0.001 - 0.1 M; The final concentration of the conductive salt is 0.01 - 0.1 M; The final concentration of the complexing agent is 0.5 - 5 times the final concentration of the main salt; The final concentration of the additive is 0.005 - 0.01 M.

7. Application of the electroplating solution according to any one of claims 1 - 6 in preparing an electrolytic water hydrogen evolution electrode.

8. A method for preparing an electrolytic water hydrogen evolution electrode, characterized in that, It includes the following steps: Clean and pre-treat the electrode substrate to obtain the pre-treated substrate; Use the pre-treated substrate as the cathode and perform electroplating treatment with the electroplating solution according to any one of claims 1 - 6 to obtain the electroplated cathode; Perform post-treatment on the electroplated cathode to obtain an electrolytic water hydrogen evolution electrode; The electroplating treatment uses stepped-current constant-current electroplating. The current density in the first stage is 0 A / m 2 , and the electroplating time ranges from 4 s to 1 min. The current density in the second stage ranges from 20 to 100 A / m 2 , and the electroplating time ranges from 1 to 150 s; The post-treatment includes rolling treatment, annealing treatment or hot pressing treatment.

9. The preparation method according to claim 8, characterized in that, The anode used in the electroplating treatment is a nickel mesh or a stainless steel sheet; The temperature of the electroplating treatment is 80 - 95 °C; The electrode spacing of the electroplating treatment is 2 - 30 cm; The electroplating treatment is accompanied by stirring, and the stirring includes magnetic stirring, cathode vibration or peristaltic pump treatment; The cleaning pre-treatment includes successively using alkali solution ultrasonic treatment, high-purity water ultrasonic treatment, dilute hydrochloric acid ultrasonic treatment, and high-purity water ultrasonic treatment; The temperature of the annealing treatment is 200 - 600 °C, the time is 30 - 120 min, the heating rate is 3 - 10 °C / min, and the gas atmosphere is air, nitrogen or an inert gas containing 3 - 8% hydrogen; The temperature of the hot pressing treatment is 60~180 °C, the pressure is 0.1~3 MPa, and the time is 5 s~3 min.

10. The electrolytic water hydrogen evolution electrode prepared by the preparation method according to claim 8 or 9.

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