A trimetallic site synergistically regulated alkaline water electrolysis electrode and a preparation method and application thereof

Abstract

The application belongs to the field of hydrogen production by water electrolysis, and specifically discloses a three-metal site synergistically regulated alkaline water electrolysis electrode and a preparation method and application thereof. The preparation method comprises the following steps: lignin sulfonate oxidation; mixing the oxidized lignin sulfonate with metal salts, the metals including Ru, Ce and Sm, and performing a hydrothermal reaction with a base carrier to obtain an electrode precursor; and calcining the electrode precursor to obtain the three-metal site synergistically regulated alkaline water electrolysis electrode. Compared with the prior art, the application has the following beneficial effects: the base and the surface high-activity component are more closely combined, and the catalyst falling-off phenomenon in the use process is avoided. The Sm and Ce doping has a certain electronic regulation and strain regulation effect on the active Ru site in the electrode, so as to improve the catalytic activity and reaction stability of the electrode.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of hydrogen production by water electrolysis, and particularly relates to a three-metal site synergistically regulated alkaline water electrolysis electrode and a preparation method and application thereof. BACKGROUND

[0002] In recent years, with the intensification of energy crisis and environmental problems, the demand for global sustainable development has become increasingly urgent. In this context, the development of clean and renewable energy is considered as a key way to cope with these challenges. Hydrogen, due to its high energy density, zero carbon emissions and renewability, has become an ideal energy carrier and one of the current research hotspots. Electrolysis of water driven by renewable energy is a green and environmentally friendly technology for producing high-purity hydrogen, which not only avoids the consumption of fossil fuels, but also makes full use of abundant electrical energy, and has important significance for promoting global energy transformation and achieving sustainable development. At present, electrolysis of water can be divided into alkaline electrolysis of water and acidic electrolysis of water according to the environment of the electrolyte, and alkaline electrolysis of water has relatively more application prospects due to its low cost and high commercialization degree without noble metals.

[0003] In the process of electrolysis of water, the electrode reaction can be divided into the anode end oxygen evolution reaction and the cathode end hydrogen evolution reaction. The anode end oxygen evolution reaction is a four-electron transfer process, which requires a large free energy and has a complicated procedure, and is the rate-determining step in the process of electrolysis of water. Therefore, in order to achieve efficient and long-term operation of alkaline electrolysis of water, a high-activity and high-stability anode electrode needs to be developed.

[0004] The most commonly used nickel electrode and Raney nickel electrode in alkaline electrolysis of water cannot achieve a good balance between reaction activity and stability, and it is difficult to meet the current demand of people. Transition metals and rare earth elements have electronic structure diversity due to their unique electronic orbital structure, and therefore transition metal and rare earth element oxides are considered as potential electrode materials for alkaline electrolysis of water. However, the traditional metal oxides or single-metal doped oxides are difficult to have high activity and high stability at the same time in practical application.

[0005] CN117107252A discloses a rare earth Ce-doped RuO2 catalyst, a preparation method and application thereof. The RuO2 catalyst is a hollow sphere structure, and the rare earth Ce is doped on the surface of the hollow sphere. Ce induces Ru surface charge rearrangement, enhances the adsorption capacity of the electrode surface to intermediates (*OH, *OOH) to enhance the catalytic capacity. It is known that the increase of the valence state of Ru causes the d-band center to be close to the Fermi level, thereby improving the interaction capacity between Ru and oxygen-containing intermediates. However, the Ru-based catalyst as an electrolysis of water electrode has a deficiency in stability, mainly due to the peroxidation dissolution of Ru. Although the high valence state of Ru is beneficial to improve the performance, it is not conducive to the stability of the electrode.

[0006] The prior art has not reported the technology of Sm-doped Ru-based catalysts. The preparation of a catalyst doped with more than one metal oxide lies in how to enable different metals to synergistically improve the catalytic activity and stability under certain preparation process conditions after being doped. SUMMARY

[0007] To overcome this problem, the purpose of the present application is to provide a three-metal site synergistically regulated alkaline water electrolysis electrode and a preparation method and application thereof. The present application prepares a Sm and Ce-doped RuO2 catalyst electrode grown in situ on the surface of an electrode by an in-situ growth method. Based on the variable valence electron structure of Ce and the unique magnetic structure of Sm, the doping of Ce has a certain electronic regulation effect on the active Ru sites in the electrode (making Ru obtain electrons and reducing the valence) under certain preparation methods and doping ratios, thereby improving the catalytic activity of the electrode and being beneficial to the stability of the electrode. The doping of Sm has a certain strain regulation effect on the active Ru sites in the electrode (shortening the Ru-O bond length) under certain preparation methods and doping ratios, thereby improving the reaction stability of the electrode. The synergistic regulation of the three-metal sites effectively solves the problems of low activity and poor stability of the electrode in the prior art.

[0008] To achieve the above purpose, the present application adopts the following scheme:

[0009] A preparation method of a three-metal site synergistically regulated alkaline water electrolysis electrode, comprising the following steps:

[0010] (1) oxidizing lignosulfonate in a solution to obtain an oxidized lignosulfonate solution;

[0011] (2) adding ammonia water to adjust the pH of the oxidized lignosulfonate solution, and then adding metal salts in proportion, the metals including Ru, Ce and Sm, mixing, and then performing hydrothermal reaction with a substrate carrier, the hydrothermal reaction temperature being 80-120 DEG C and the time being 3-10 h, to obtain an electrode precursor;

[0012] (3) calcining the electrode precursor obtained in (2) at a calcination temperature of 200-600 DEG C for 1-8 h to obtain a three-metal site synergistically regulated alkaline water electrolysis electrode.

[0013] In the present application, metal ions form complexes through complexation with lignosulfonate, and are adsorbed onto the substrate carrier through hydroxyl groups, sulfonic acid groups and the like. Finally, the metals are connected through oxygen elements after calcination.

[0014] Preferably, in step (1), the lignin sulfonate is added to a solution (i.e., a mixture of water and ethanol, and the ethanol refers to anhydrous ethanol), ultrasonic dispersion is mixed, a small amount of hydrogen peroxide is added, and the lignin sulfonate is subjected to oxidation treatment to obtain an oxidized lignin sulfonate solution. By oxidizing the lignin sulfonate, the complexing ability of the lignin sulfonate to metals is improved.

[0015] Preferably, in step (1), the ratio of the lignin sulfonate to hydrogen peroxide added is 8-16 mmol:0.1-1 mL; the volume ratio of water to ethanol is (1-9):1; and the ultrasonic dispersion time is 1-10 min.

[0016] In step (2), ammonia is added to the oxidized lignin sulfonate solution obtained in (1) to adjust the pH to weak alkaline, which is conducive to the complexation of the lignin sulfonate with metal ions. Metal salts RuCl3, Ce(NO3)3, and Sm(NO3)3 are sequentially added in proportion, and after ultrasonic dispersion, the electrode precursor is obtained by placing the mixture in a hydrothermal kettle together with a substrate carrier, rinsing the electrode surface with deionized water after hydrothermal reaction. Ru salt is added first, so that the main components are distributed in the interior, and the metal elements responsible for regulation are distributed on the surface layer, which can better contact the reaction interface and improve the utilization rate of doped elements.

[0017] Preferably, in step (2), the volume ratio of the ammonia added to the hydrogen peroxide added in step (1) is 0.1-1.5:0.1-1; and the metal salt is RuCl3, Ce(NO3)3, or Sm(NO3)3.

[0018] Preferably, in step (2), the molar ratio of RuCl3, Ce(NO3)3, and Sm(NO3)3 added is (6.9-7.1):(1.9-2.1):(0.9-1.1).

[0019] In step (2), the mixture is mixed by ultrasonic dispersion, and the ultrasonic dispersion time is 1-5 h.

[0020] In step (2), the substrate carrier is one of foamed nickel, nickel mesh, and carbon paper.

[0021] In step (3), the electrode precursor obtained in (2) is placed in a muffle furnace for calcination, so that the metal ions on the electrode surface are further oxidized, and the metal oxides adsorbed on the surface are more closely combined with the substrate carrier. Subsequently, the electrode sheet is removed and rinsed with deionized water to remove unstable components on the surface, and the high-activity stable alkaline electrolytic water electrode with three-metal site synergistic regulation is obtained after drying.

[0022] Preferably, in step (3), the calcination temperature is 300-500°C.

[0023] Preferably, in step (3), the drying method is at least one of ordinary drying, vacuum drying, and freeze drying.

[0024] Another object of the present application is to provide a three-metal site synergistically regulated alkaline electrolysis water electrode prepared by the aforementioned preparation method.

[0025] Still another object of the present application is to disclose the application of the three-metal site synergistically regulated alkaline electrolysis water electrode in electrolysis of water to produce hydrogen, especially in alkaline electrolysis of water to produce hydrogen. Specifically, the alkaline electrolysis of water to produce hydrogen is carried out in an electrolysis cell device. The electrolysis cell device comprises an electrolysis cell clamp, a peristaltic pump, an alkali tank, and a temperature control device.

[0026] Preferably, the diaphragm used in the electrolysis cell is Zirfon PERL UTP 500 alkaline electrolysis water composite diaphragm.

[0027] Preferably, the flow rate of the electrolyte is 0-100 mL / min.

[0028] Preferably, the electrolyte temperature during the electrolysis reaction is 60-80℃.

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] 1) The present application provides a three-metal site synergistically regulated alkaline electrolysis water electrode, which is prepared by hydrothermal method to precipitate the required metal oxide catalyst on a substrate carrier; the in-situ growth method is more closely combined with the substrate and the surface high-activity component than the traditional coating method, thereby avoiding the falling phenomenon of the catalyst during use.

[0031] 2) The lignin sulfonate used in the present application, in addition to containing rich hydroxyl groups, also contains sulfonic acid groups, which are all conducive to the complexation reaction of the lignin sulfonate with metal ions in aqueous solution, and the complexation capacity of the metal ions can be further improved after the lignin sulfonate is subjected to oxidation treatment, thereby further improving the catalytic performance.

[0032] 3) The Sm and Ce doped RuO2 catalyst electrode provided by the present application has certain electronic regulation effect (making Ru obtain electrons and reducing the valence state) on the active Ru site in the electrode under certain preparation method and doping ratio conditions based on the variable valence electron structure of Ce and the unique magnetic structure of Sm, thereby improving the catalytic activity of the electrode and being beneficial to the stability of the electrode; and the Sm doping has certain strain regulation effect (shortening the Ru-O bond length) on the active Ru site in the electrode under certain preparation method and doping ratio conditions, thereby improving the reaction stability of the electrode. Therefore, the electrode can reach 830 mA / cm2 and 900 mA / cm2 at 1.8 V and 2.0 V, respectively, in the application of alkaline electrolysis of water.2 and 1500 mA / cm 2 and can be stably operated for more than 500 h at a current density of 1000 mA / cm 2 , and has good hydrogen production performance. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiment schematic diagrams of the present application, and therefore should not be considered as a limitation on the scope. Other related drawings can also be obtained from these drawings by those skilled in the art without paying too much creative labor.

[0034] Figure 1 Scanning electron microscope image of the electrode described in Example 2 of the present application;

[0035] Figure 2 X-ray photoelectron spectroscopy of active Ru sites of the electrode described in Example 2 of the present application and different electrodes of Comparative Example 1, Comparative Example 2 and Comparative Example 3;

[0036] Figure 3 XANES spectrum of the electrode described in Example 2 and different electrodes of Comparative Example 1, Comparative Example 2 and Comparative Example 3;

[0037] Figure 4 Electrochemical performance comparison of the electrode described in Example 2 of the present application and different electrodes of Comparative Example 1, Comparative Example 2 and Comparative Example 3;

[0038] Figure 5 Stability test results of the electrode described in Example 2 of the present application in 30% KOH at a current density of 1000 mA / cm 2 . DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application will be further described in detail below in combination with embodiments. Of course, the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0040] Unless otherwise specified, the chemical reagents and materials in the present application are purchased through market channels, or synthesized from raw materials purchased through market channels.

[0041] The present application discloses a preparation method of a high-activity stable alkaline water electrolysis electrode with three-metal site synergistic regulation, comprising the following steps:

[0042] (1) adding lignin sulfonate into a mixture of water and ethanol, adding a small amount of hydrogen peroxide by ultrasonic dispersion, oxidizing lignin sulfonate, and improving the complexing ability of lignin sulfonate to metal.

[0043] Specifically, the added lignin sulfonate is 8-16 mmol.

[0044] Specifically, the volume ratio of water to ethanol is (1-9):1.

[0045] Specifically, the ultrasonic time is 1-10 min.

[0046] Specifically, the volume of hydrogen peroxide added is 0.1-1 mL.

[0047] (2) Subsequently, in the solution obtained in (1), ammonia is added to adjust the pH to weak alkaline (for example, 7-9), which is conducive to the complexation of lignin sulfonate and metal ions, and metal salts are sequentially added in proportion, and after ultrasonic dispersion, they are placed in a hydrothermal kettle together with the base carrier, and after hydrothermal reaction, the electrode (i.e. the base carrier loaded with metal salts, at this time the electrode state is the complexation state of the metal ions connected by the organic acid, and the water washing removes the unreacted metal ions and organic acid, and the complex state is not enough to achieve the ideal electrolysis performance, and further calcination is needed to generate oxide) surface is washed with deionized water to obtain an electrode precursor.

[0048] Specifically, the volume of ammonia added is 0.1-1.5 mL.

[0049] Specifically, the metal salt is RuCl3, Ce(NO3)3, or Sm(NO3)3.

[0050] Specifically, the added metal elements and their proportions are (6.9-7.1):(1.9-2.1):(0.9-1.1).

[0051] Specifically, the ultrasonic dispersion time is 1-5 h.

[0052] Specifically, the base carrier is one of foamed nickel, nickel mesh, and carbon paper.

[0053] Specifically, the hydrothermal reaction temperature is 80-120℃, and the time is 3-10 h.

[0054] (3) Put the precursor obtained in (2) into a muffle furnace for calcination, so as to further oxidize the metal ions on the surface of the electrode and make the metal oxides adsorbed on the surface more closely combined with the base carrier, and then take out the electrode sheet (i.e. the base carrier loaded with metal oxides) to be washed with deionized water to remove the unstable components on the surface (i.e. unreacted metal ions and organic acids), and after drying, the high-activity stable alkaline electrolytic water electrode with three-metal site synergistic regulation is obtained.

[0055] Specifically, the calcination temperature is 200-600°C, and the time is 1-8h.

[0056] Specifically, the drying method is at least one of ordinary drying, vacuum drying and freeze drying.

[0057] The application will be further described below through specific examples.

[0058] Example 1

[0059] A preparation method of a high-activity stable alkaline electrolytic water electrode with three-metal site synergistic regulation comprises the following steps:

[0060] (1) 8mmol of sodium lignosulfonate (purchased from Merck Company, the same below) is added into 50mL of water and 50mL of ethanol mixed solution, and ultrasonic dispersion is carried out for 2min, and then 0.2mL of hydrogen peroxide is added, and ultrasonic dispersion is carried out for 5min (in this process, dissolution, mixing and oxidation are carried out).

[0061] (2) The solution obtained in (1) is added with 0.2mL of ammonia water to adjust the pH, and then RuCl3, Ce(NO3)3 and Sm(NO3)3 are sequentially added, wherein the mass of RuCl3 is 1.452g, and the molar ratio of RuCl3, Ce(NO3)3 and Sm(NO3)3 is 7:1.9:0.9, and ultrasonic dispersion is carried out for 2h, and then the nickel mesh (Φ=3cm) after cutting is put into an autoclave together with the solution to react at 120°C for 5h, and after hydrothermal reaction, the solution is washed with deionized water to obtain the electrode precursor.

[0062] (3) The precursor obtained after hydrothermal reaction is put into a muffle furnace for calcination at 300°C for 5h, so as to further oxidize the metal ions which are not completely reacted and make the metal oxides adsorbed on the surface more closely combined with the nickel mesh, and then the electrode sheet is taken out to be washed with deionized water to remove the unstable components on the surface, and after freeze drying, the alkaline electrolytic water electrode is obtained.

[0063] Example 2

[0064] A preparation method of a high-activity stable alkaline electrolytic water electrode with three-metal site synergistic regulation comprises the following steps:

[0065] (1) 10 mmol of sodium lignosulfonate was added to a mixture of 70 mL of water and 30 mL of ethanol, and ultrasonic dispersion was performed for 4 min. 0.2 mL of hydrogen peroxide was added, and ultrasonic dispersion was performed for 5 min.

[0066] (2) The solution obtained in (1) was added with 0.4 mL of ammonia water to adjust the pH, and then RuCl3, Ce(NO3)3 and Sm(NO3)3 were sequentially added, wherein the mass of RuCl3 was 1.452 g, and the molar ratio of RuCl3, Ce(NO3)3 and Sm(NO3)3 was 7:2:1. Ultrasonic dispersion was performed for 2 h, and the ultrasonic dispersion was placed in a hydrothermal kettle together with a nickel mesh (Φ = 3 cm) at 100 ℃ for 5 h. After hydrothermal treatment, the electrode precursor was obtained by washing with deionized water.

[0067] (3) The precursor obtained after hydrothermal treatment was placed in a muffle furnace and calcined at 400 ℃ for 4 h, so as to further oxidize the metal ions that were not completely reacted and make the metal oxides adsorbed on the surface more closely combined with the nickel mesh. Then, the electrode sheet was taken out and washed with deionized water to remove the unstable components on the surface. After freeze-drying, the alkaline electrolytic water electrode was obtained.

[0068] Example 3

[0069] A preparation method of a high-activity stable alkaline electrolytic water electrode synergistically regulated by three metal sites, comprising the following steps:

[0070] (1) 12 mmol of sodium lignosulfonate was added to a mixture of 60 mL of water and 40 mL of ethanol, and ultrasonic dispersion was performed for 6 min. 0.6 mL of hydrogen peroxide was added, and ultrasonic dispersion was performed for 5 min.

[0071] (2) The solution obtained in (1) was added with 0.8 mL of ammonia water to adjust the pH, and then RuCl3, Ce(NO3)3 and Sm(NO3)3 were sequentially added, wherein the mass of RuCl3 was 1.452 g, and the molar ratio of RuCl3, Ce(NO3)3 and Sm(NO3)3 was 7.1:2:1.1. Ultrasonic dispersion was performed for 2 h, and the ultrasonic dispersion was placed in a hydrothermal kettle together with a nickel mesh (Φ = 3 cm) at 90 ℃ for 5 h. After hydrothermal treatment, the electrode precursor was obtained by washing with deionized water.

[0072] (3) The precursor obtained after hydrothermal treatment was placed in a muffle furnace and calcined at 500 ℃ for 4 h, so as to further oxidize the metal ions that were not completely reacted and make the metal oxides adsorbed on the surface more closely combined with the nickel mesh. Then, the electrode sheet was taken out and washed with deionized water to remove the unstable components on the surface. After freeze-drying, the alkaline electrolytic water electrode was obtained.

[0073] Comparative Example 1

[0074] A preparation method of a single metal site regulated alkaline electrolysis water electrode, comprising the following steps:

[0075] (1) 10 mmol of sodium lignosulfonate was added to a mixture of 70 mL of water and 30 mL of ethanol, ultrasonic dispersion for 4 min, 0.2 mL of hydrogen peroxide was added, and ultrasonic dispersion was performed for 5 min.

[0076] (2) The solution obtained in (1) was added with 0.4 mL of ammonia water to adjust pH, then 1.452 g of RuCl3 was added and ultrasonic dispersion was performed for 2 h, and the nickel mesh (Φ=3 cm) after cutting was put into an autoclave at 100 DEG C for reaction for 5 h, and after hydrothermal reaction, deionized water was used for washing, and the electrode precursor was obtained.

[0077] (3) The precursor obtained after hydrothermal reaction was put into a muffle furnace for calcination at 400 DEG C for 4 h, so as to further oxidize the metal ions which were not completely reacted, and the metal oxides adsorbed on the surface were more closely combined with the nickel mesh, then the electrode sheet was taken out and washed with deionized water to remove the unstable components on the surface, and after freeze-drying, the alkaline electrolysis water electrode was obtained.

[0078] Comparative example 2

[0079] A preparation method of a double metal site regulated high-activity stable alkaline electrolysis water electrode, comprising the following steps:

[0080] (1) 10 mmol of sodium lignosulfonate was added to a mixture of 70 mL of water and 30 mL of ethanol, ultrasonic dispersion was performed for 4 min, 0.2 mL of hydrogen peroxide was added, and ultrasonic dispersion was performed for 5 min.

[0081] (2) The solution obtained in (1) was added with 0.4 mL of ammonia water to adjust pH, then RuCl3 and Sm(NO3)3 were sequentially added, the mass of RuCl3 was 1.452 g, and the molar ratio of RuCl3 to Sm(NO3)3 was 7:1, ultrasonic dispersion was performed for 2 h, and the nickel mesh (Φ=3 cm) after cutting was put into an autoclave at 100 DEG C for reaction for 5 h, and after hydrothermal reaction, deionized water was used for washing, and the electrode precursor was obtained.

[0082] (3) The precursor obtained after hydrothermal reaction was put into a muffle furnace for calcination at 400 DEG C for 4 h, so as to further oxidize the metal ions which were not completely reacted, and the metal oxides adsorbed on the surface were more closely combined with the nickel mesh, then the electrode sheet was taken out and washed with deionized water to remove the unstable components on the surface, and after freeze-drying, the alkaline electrolysis water electrode was obtained.

[0083] Comparative example 3

[0084] A preparation method of a double metal site regulated high-activity stable alkaline electrolysis water electrode, comprising the following steps:

[0085] (1) 10 mmol of sodium lignosulfonate was added to a mixture of 70 mL of water and 30 mL of ethanol, ultrasonic dispersion for 4 min, 0.2 mL of hydrogen peroxide was added, ultrasonic dispersion for 5 min.

[0086] (2) The solution obtained in (1) was added to 0.4 mL of ammonia water to adjust the pH, and then RuCl3, Ce(NO3)3 were added in sequence, wherein the mass of RuCl3 was 1.452 g, and the molar ratio of RuCl3 to Ce(NO3)3 was 7:2, ultrasonic dispersion for 2 h, and then placed in a hydrothermal kettle together with a cut nickel mesh (Φ=3 cm) at 100°C for 5 h, and then washed with deionized water after hydrothermal reaction to obtain the electrode precursor.

[0087] (3) The precursor obtained after hydrothermal reaction was placed in a muffle furnace and calcined at 400°C for 4 h, so that the metal ions that were not completely reacted were further oxidized, and the metal oxides adsorbed on the surface were more closely combined with the nickel mesh, and then the electrode sheet was taken out and washed with deionized water to remove the unstable components on the surface, and then freeze-dried to obtain the alkaline electrolytic water electrode.

[0088] Comparative Example 4

[0089] A preparation method of a three-metal site synergistically regulated alkaline electrolytic water electrode, comprising the following steps:

[0090] (1) 10 mmol of sodium lignosulfonate was added to a mixture of 70 mL of water and 30 mL of ethanol, ultrasonic dispersion for 4 min, 0.2 mL of hydrogen peroxide was added, ultrasonic dispersion for 5 min.

[0091] (2) The solution obtained in (1) was added to 0.4 mL of ammonia water to adjust the pH, and then RuCl3, Ce(NO3)3, Cr(NO3)2 were added in sequence, wherein the mass of RuCl3 was 1.452 g, and the molar ratio of RuCl3 to Ce(NO3)3 to Cr(NO3)2 was 7:2:1, ultrasonic dispersion for 2 h, and then placed in a hydrothermal kettle together with a cut nickel mesh (Φ=3 cm) at 100°C for 5 h, and then washed with deionized water after hydrothermal reaction to obtain the electrode precursor.

[0092] (3) The electrode precursor obtained after hydrothermal reaction was placed in a muffle furnace and calcined at 400°C for 4 h, so that the metal ions that were not completely reacted were further oxidized, and the metal oxides adsorbed on the surface were more closely combined with the nickel mesh, and then the electrode sheet was taken out and washed with deionized water to remove the unstable components on the surface, and then dried to obtain the alkaline electrolytic water electrode.

[0093] Comparative Example 5

[0094] A preparation method of a three-metal site synergistically regulated alkaline electrolytic water electrode, comprising the following steps:

[0095] (1) 10 mmol of sodium lignosulfonate was added to a mixture of 70 mL of water and 30 mL of ethanol, ultrasonic dispersion for 4 min, 0.2 mL of hydrogen peroxide was added, ultrasonic dispersion for 5 min.

[0096] (2) The solution obtained in (1) was added with 0.4 mL of ammonia water to adjust the pH, and then RuCl3, Mn(NO3)2 and Cr(NO3)2 were sequentially added, wherein the mass of RuCl3 was 1.452 g, and the molar ratio of RuCl3, Mn(NO3)2 and Cr(NO3)2 was 7:2:1, ultrasonic dispersion for 2 h, and then the nickel mesh (Φ = 3 cm) after cutting was placed in an autoclave at 100 ℃ for 5 h, and then the electrode precursor was obtained after hydrothermal treatment and deionized water washing.

[0097] (3) The precursor obtained after hydrothermal treatment was placed in a muffle furnace and calcined at 400 ℃ for 4 h, so as to further oxidize the metal ions which were not completely reacted, and make the metal oxides adsorbed on the surface more closely combined with the carbon paper, and then the electrode sheet was taken out and washed with deionized water to remove the unstable components on the surface, and the alkaline electrolytic water electrode was obtained after vacuum drying.

[0098] Comparative Example 6

[0099] A preparation method of a three-metal site synergistically regulated alkaline electrolytic water electrode, comprising the following steps:

[0100] (1) 10 mmol of sodium lignosulfonate was added to a mixture of 70 mL of water and 30 mL of ethanol, ultrasonic dispersion for 4 min, 0.2 mL of hydrogen peroxide was added, ultrasonic dispersion for 5 min.

[0101] (2) The solution obtained in (1) was added with 0.4 mL of ammonia water to adjust the pH, and then RuCl3, Mn(NO3)2 and La(NO3)2 were sequentially added, wherein the mass of RuCl3 was 1.452 g, and the molar ratio of RuCl3, Mn(NO3)2 and La(NO3)2 was 7:2:1, ultrasonic dispersion for 2 h, and then the nickel mesh (Φ = 3 cm) after cutting was placed in an autoclave at 100 ℃ for 5 h, and then the electrode precursor was obtained after hydrothermal treatment and deionized water washing.

[0102] (3) The precursor obtained after hydrothermal treatment was placed in a muffle furnace and calcined at 400 ℃ for 4 h, so as to further oxidize the metal ions which were not completely reacted, and make the metal oxides adsorbed on the surface more closely combined with the carbon paper, and then the electrode sheet was taken out and washed with deionized water to remove the unstable components on the surface, and the alkaline electrolytic water electrode was obtained after vacuum drying.

[0103] Comparative Example 7

[0104] A preparation method of a three-metal site synergistically regulated alkaline water electrolysis electrode, comprising the following steps:

[0105] (1) 10 mmol of sodium lignosulfonate was added to a mixture of 70 mL of water and 30 mL of ethanol, and ultrasonic dispersion was performed for 4 min. 0.2 mL of hydrogen peroxide was added, and ultrasonic dispersion was performed for 5 min.

[0106] (2) The solution obtained in (1) was added with 0.4 mL of ammonia water to adjust the pH, and then RuCl3, Cr(NO3)2 and Sm(NO3)3 were sequentially added, wherein the mass of RuCl3 was 1.452 g, and the molar ratio of RuCl3, Cr(NO3)2 and Sm(NO3)3 was 7:2:1. Ultrasonic dispersion was performed for 5 h. The nickel mesh (Φ=3 cm) after cutting was placed in a hydrothermal kettle together at 110 ℃, and reaction was performed for 6 h. After hydrothermal treatment, the electrode precursor was obtained by washing with deionized water.

[0107] (3) The precursor obtained after hydrothermal treatment was placed in a muffle furnace and calcined at 400 ℃ for 4 h, so as to further oxidize the metal ions that were not completely reacted, and to make the metal oxides adsorbed on the surface more closely combined with the carbon paper. Then, the electrode sheet was taken out and washed with deionized water to remove the unstable components on the surface. After vacuum drying, the alkaline water electrolysis electrode was obtained.

[0108] Comparative Example 8

[0109] Compared with Example 2, the mass of RuCl3 was unchanged, the molar ratio of RuCl 3、 The molar ratio of Ce(NO3)3 and Sm(NO3)3 was adjusted to 7:2:2, 7:2:0.5, 7:1:1 and 7:3:1, respectively.

[0110] Comparative Example 9

[0111] Compared with Example 2, the step of “adding 0.2 mL of hydrogen peroxide and ultrasonic dispersion for 5 min” was omitted.

[0112] Application Example 1

[0113] The application of a three-metal site synergistically regulated high-activity stable alkaline water electrolysis electrode in electrolytic water hydrogen production, comprising the following steps:

[0114] The cleaned electrode sheet and the finished diaphragm were sequentially installed in the electrolysis tank clamp, and then connected to the test system, including a peristaltic pump, an alkali tank, a temperature control system and an electrochemical test platform. The anode was an alkaline water electrolysis electrode prepared by the example or the comparative example, and the cathode was a commercial nickel mesh electrode. The electrolysis temperature was set to 80 ℃, and after the system temperature was stabilized at 80 ℃, the test was started. The current density was 500 mA / cm 2The current density of 500 mA / cm2 was applied to activate the electrode and the diaphragm in the electrolytic cell until the performance tended to be stable, and the activation was completed. Then, the required hydrogen production performance test was carried out. First, the polarization curve test was carried out on the activated electrolytic cell, and the performance of the comparative example and the control example was compared under the same voltage. Then, the stability of the electrode was evaluated by constant current (1000 mA / cm 2 ) polarization. In order to further ensure the stability of the pH in the electrolytic cell during the reaction, the alkali solution in the alkali tank was replaced every 150 h of reaction.

[0115] Table 1 shows the charge transfer resistance of the examples and the control examples measured at a current density of 500 mA / cm 2 in application example 1, and the overpotential test results at a current density of 500 mA / cm 2 . The resistance and overpotential were tested by an electrochemical workstation, and the execution standards were GB / T 38894-2020 and GB / T 45092-2024.

[0116] Table 1 shows the electrochemical performance test results

[0117] Charge transfer resistance (Ω) 500 mA / cm 2 Overpotential (mV) Example 1 1.75 442 Example 2 1.63 430 Example 3 1.79 439 Comparative Example 1 8.47 723 Comparative Example 2 5.96 688 Comparative Example 3 4.34 562 Comparative Example 4 3.78 516 Comparative Example 5 4.15 551 Comparative Example 6 3.21 503 Comparative Example 7 10.78 975 Comparative Example 8 (7:2:2) 2.83 474 Comparative Example 8 (7:2:0.5) 2.97 487 Comparative Example 8 (7:1:1) 3.56 509 Comparative Example 8 (7:3:1) 2.57 451 Comparative Example 9 4.76 591

[0118] From Table 1, it can be seen that the synergistic catalytic effect of Ru, Ce and Sm in the alkaline electrolytic water electrode is better than that of other metal combinations (Ru / Ce / Cr, Ru / Mn / Cr, Ru / Mn / La, Ru / Sm / Cr). Comparative examples 4-7 also use three metal sites, and some metals are different from the examples. The charge transfer resistance and overpotential performance data are not as good as the examples.

[0119] Figure 1 The SEM of the catalyst generated on the surface of the electrode of Example 2 shows that metal oxide nanoparticles are grown on the surface of the original nickel mesh substrate. This in-situ growth method can effectively avoid the catalyst shedding phenomenon caused by traditional coating methods, and the metal oxide nanoparticles on the surface can provide a larger active specific surface area and enhance the electrochemical activity of the electrode.

[0120] Figure 2 The X-ray photoelectron spectroscopy of the electrode Ru of Example 2 and the control example shows that 4 + represents the peak generated by 4 + valent Ru; 0 represents the peak generated by 0 valent Ru; sat. is a satellite peak; Ru 3d, 3d 3 / 2 and 3d 5 / 2 refer to the outermost 3d orbit of Ru, which can be split into 3d 3 / 2 and 3d 5 / 2 , C 1sis the 1s orbital of carbon element. By comparing Example 2 and Comparative Example 2, it can be seen that the doping of Ce makes the active Ru site binding energy in the electrode appear a negative shift, which means that the electronic valence state of Ru is reduced to a certain extent (representing the Ru site gets electrons), and the reduction of the valence state can accelerate the reaction rate of the intermediates in the water electrolysis process, thereby accelerating the overall reaction kinetics and improving the catalytic ability of the electrode. Specifically, the electron of the Ru site can promote the reaction kinetics of the intermediates generated by water splitting, and the Ru in low valence state can also avoid the peroxidation of Ru, maintaining the stability of the electrode.

[0121] Figure 3 The normalized XANES spectrum of the electrode of Example 2 and Comparative Example is shown in the following figure. By comparing Example 2 and Comparative Example 3, it can be seen that due to the doping of Sm, the Ru-O bond length in the electrode will appear a certain shortening (about 0.05 A shortening ), and the shortening of the bond length can maintain the stability of the Ru-O bond during the reaction, avoid bond breaking and inactivation, and exhibit excellent stability of the electrode. The difficulty of shortening the Ru-O bond length lies in accurately regulating the structure of the catalyst, especially the local atomic arrangement, which is closely related to the metal molar ratio and the preparation method of the present application.

[0122] Figure 3 The abscissa R represents the bond length; the ordinate represents the absorption coefficient, which means the intensity or represents the strength of the bond. Ru K-edge represents the characteristic X-ray absorption edge of Ru, which reflects the relationship between the energy of X-ray and the binding energy of the K electron shell of the target atom.

[0123] Figure 4 By comparing the polarization curves of the electrodes of Example 2 and Comparative Example, it can be seen that, relative to the comparative examples, the electrode described in Example 2 produces a larger current density at the same voltage, which means that its hydrogen production efficiency is higher and the energy consumption is lower in actual production. Among them, the electrode described in Example 2 can reach a current density of 830 mA / cm 2 and 1500 mA / cm 2 at voltages of 1.8 V and 2.0 V, respectively, which is superior in performance to the electrodes described in Comparative Examples 1, 2 and 3. Specifically, Comparative Example 1: 1.8 V (278 mA / cm 2 ), 2.0 V (627 mA / cm 2 ); Comparative Example 2: 1.8 V (312 mA / cm 2 ), 2.0 V (686 mA / cm 2 ); Comparative Example 3: 1.8 V (535 mA / cm 2 ), 2.0 V (935 mA / cm 2 ).

[0124] Figure 5The constant current polarization curves of the electrodes described in Example 2 and the comparative examples at a current density of 1000 mA / cm 2 It can be observed that the electrode obtained in Example 2 can be operated stably and efficiently for more than 500 h without obvious performance attenuation, which fully proves the excellent stability of the electrode. The stable operation time of Comparative Example 1 is less than 100 h due to the absence of Sm and Ce doping; the stability of the electrode: Example 2 > Comparative Example 2 > Comparative Example 3 > Comparative Example 1. It can be known that Sm and Ce doping can synergistically improve the stability of the electrode. Figure 5

[0125] The above merely describes the preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent replacements or changes according to the technical scheme and the inventive concept of the present application within the technical range disclosed by the present application, which are all covered within the protection scope of the present application.​

Claims

1. A method for preparing a three-metal site synergistically regulated alkaline electrolytic water electrode, characterized in that, The method comprises the following steps: (1) oxidizing lignosulfonate in a solution to obtain an oxidized lignosulfonate solution; (2) adjusting the pH of the oxidized lignosulfonate solution by adding ammonia water, and then adding metal salts in proportion, wherein the metal includes Ru, Ce and Sm, mixing, and then performing a hydrothermal reaction with a base carrier, wherein the hydrothermal reaction temperature is 80-120 DEG C, and the reaction time is 3-10 h, to obtain an electrode precursor; (3) calcining the electrode precursor obtained in step (2) at a calcining temperature of 200-600 DEG C for 1-8 h to obtain a three-metal site synergistically controlled alkaline electrolytic water electrode. In step (2), the metal salts are RuCl3, Ce(NO3)3 and Sm(NO3)3, and the molar ratio of RuCl3, Ce(NO3)3 and Sm(NO3)3 is (6.9-7.1) : (1.9-2.1) : (0.9-1.1).

2. The method for preparing a three-metal site synergistically regulated alkaline electrolytic water electrode according to claim 1, characterized in that, In step (1), the lignosulfonate is added to a mixture of water and ethanol, ultrasonic dispersion is performed, a small amount of hydrogen peroxide is added, and the lignosulfonate is oxidized to obtain an oxidized lignosulfonate solution.

3. The method for preparing a three-metal site synergistically regulated alkaline electrolytic water electrode according to claim 2, characterized in that, In step (1), the ratio of lignosulfonate to hydrogen peroxide is 8-16 mmol: 0.1-1 mL, and the volume ratio of water to ethanol is (1-9) : 1, and the ultrasonic dispersion time is 1-10 min.

4. The method of claim 2, wherein the method is characterized by: In step (2), the volume ratio of ammonia water to hydrogen peroxide added in step (1) is 0.1-1.5 : 0.1-1.

5. The method of claim 2, wherein the method is characterized by: In step (2), the mixture is mixed by ultrasonic dispersion, and the ultrasonic dispersion time is 1-5 h.

6. The method of claim 2, wherein the method is characterized by: In step (2), the base carrier is one of foamed nickel, a nickel mesh and carbon paper.

7. The method of claim 2, wherein the method is characterized by: In step (3), the calcining temperature is 300-500 DEG C.

8. A three-metal site synergistically controlled alkaline electrolytic water electrode prepared by the preparation method of any one of claims 1-7.

9. Application of the three-metal site synergistically controlled alkaline electrolytic water electrode of claim 8 as an anode in electrolytic water hydrogen production.

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