Catalyst and anode for electrolytic production of hydrogen, and preparation methods therefor, activation methods therefor and use thereof

Abstract

Disclosed in the present application are a catalyst and anode for electrolytic production of hydrogen, and preparation methods therefor, activation methods therefor and the use thereof. In one embodiment, the anode for electrolytic production of hydrogen comprises a catalyst, wherein the catalyst is nickel-iron-barium hydrotalcite and has a hexagonal nanoflake structure, the thickness thereof being 100-200 nm. The catalyst can be prepared by means of a one-step solvothermal reaction method. In the present application, alkaline earth metal ions are uniformly doped in nickel-iron hydrotalcite and are dispersed at an atomic level, such that when the anode for electrolytic production of hydrogen based on the catalyst is applied to a process for electrolytic production of hydrogen from an aqueous solution containing chloride ions, the anode not only retains good catalytic performance, but also has greatly improved resistance to chloride ion corrosion, significantly improved working stability and a significantly prolonged service life.

Description

Electrolytic hydrogen production catalyst, anode and preparation method, activation method and application thereof

[0001] This application claims priority to the Chinese invention patent application with application number CN202310720257.3, application date June 16, 2023, and title “Electrolysis hydrogen production anode and its preparation method, activation method and application”, and application number CN202410452007.0, application date April 15, 2024, and title “Electrolysis hydrogen production catalyst, anode and its preparation method, activation method and application”. The above patent applications are incorporated herein by reference in their entirety. Technical Field

[0002] The present application belongs to the field of materials and energy catalysis technology, and specifically relates to an electrolytic hydrogen production catalyst, an anode, and a preparation method, activation method, and application thereof. Background Art

[0003] Carbon emissions from the energy sector account for two-thirds of global greenhouse gas emissions. Hydrogen is one of the most promising energy carriers, potentially replacing fossil fuels and addressing future global warming. Hydrogen production through water electrolysis, powered by renewable energy, could provide a new path to alleviate current energy shortages without compromising environmental sustainability.

[0004] The hydrogen produced by water electrolysis is of high purity, and its high energy consumption can be reduced through technical means. However, the limited availability of freshwater resources significantly restricts its development and large-scale application. From a practical perspective, direct seawater electrolysis offers significant advantages. The Earth's abundant seawater reserves provide the foundation for large-scale application, and it also has the ability to produce high-purity hydrogen.

[0005] However, there are some more serious problems to be solved when using seawater electrolysis directly. For example, seawater electrolysis for hydrogen production apparently includes two half reactions, namely the anodic oxygen evolution reaction and the cathode hydrogen evolution reaction. Under alkaline conditions, the kinetics of the oxygen evolution reaction (OER) are slow, and the high concentration of chloride ions in seawater will compete with the anodic oxygen evolution reaction and cause severe corrosion to the anode, resulting in a shortened service life. Although catalysts such as RuO2 and IrO2 have been used as anodes for electrolysis, there is an urgent need to develop OER catalysts with high activity, high selectivity, good stability, low cost and abundant reserves.

[0006] Previous studies have developed a range of OER catalysts in alkaline solutions, including hydroxides, metal oxides, sulfides, and phosphides. However, at industrial current densities, seawater electrolysis has not yet achieved long-term stability (100 to 1000 hours). Therefore, the development of efficient and stable anodes for seawater electrolysis to produce oxygen has become an urgent need.

[0007] Some non-precious metal oxygen evolution catalysts, such as nickel-iron hydrotalcite (see CN114657591A and CN114657591B), have been widely reported and studied due to their excellent performance and low cost. However, they are easily corroded in seawater, resulting in a short service life, which severely limits their application in chloride ion-containing aqueous solutions, especially in seawater electrolysis for hydrogen production.

[0008] Summary of the Invention

[0009] The main purpose of this application is to provide an electrolytic hydrogen production catalyst, an anode and its preparation method, activation method and application to overcome the deficiencies in the prior art.

[0010] To achieve the aforementioned invention objectives, the technical solutions adopted in this application are as follows:

[0011] The first aspect of the present application provides a catalyst for electrolytic hydrogen production, the chemical formula of which is [M 1-x N x M'(OH)2] x+ [(A n- ) x / n mH2O] x- , M and N are any two ions of scandium, vanadium, chromium, manganese, iron, cobalt and nickel, and M and N are in the chemical valence state of +2 and +3 respectively, M' is selected from alkaline earth metal ions and is atomically dispersed in the catalyst, A n- Selected from CO3 2- 、NO3 2- 、Cl - OH - or SO4 2- , x=0.17~0.33, m is an integer greater than or equal to 0, and n=1~3.

[0012] The second aspect of the present application provides a method for preparing an electrolytic hydrogen production catalyst, which comprises: subjecting a mixed reaction solution containing M, N and M' to a hydrothermal reaction to prepare an electrolytic hydrogen production catalyst, wherein the chemical formula of the catalyst is [M 1-x N x M'(OH)2] x+ [(A n- ) x / n mH2O] x- , wherein M and N are any two ions of scandium, vanadium, chromium, manganese, iron, cobalt, and nickel, and M and N are in the chemical valence states of +2 and +3, respectively, M' is selected from alkaline earth metal ions and is atomically dispersed in the catalyst, A n- Selected from CO3 2- 、NO3 2- 、Cl - OH - or SO4 2-, x=0.17~0.33, m is an integer greater than or equal to 0, and n=1~3.

[0013] The third aspect of the present application provides an activated electrolytic hydrogen production catalyst, which includes the electrolytic hydrogen production catalyst and a sulfate activation layer, wherein the sulfate activation layer includes sulfate ions distributed on the surface of the catalyst, and the sulfate ions are combined with alkaline earth metal ions in the catalyst.

[0014] The fourth aspect of the present application provides a seawater electrolysis hydrogen production anode, which includes the electrolysis hydrogen production catalyst or the activated electrolysis hydrogen production catalyst.

[0015] The fifth aspect of the present application provides the use of the electrolytic hydrogen production catalyst, the activated electrolytic hydrogen production catalyst or the electrolytic hydrogen production anode in electrolytic hydrogen production.

[0016] The sixth aspect of the present application provides a method for producing hydrogen by electrolysis, which comprises: placing the anode and cathode of the electrolytic hydrogen production into an aqueous solution containing chloride ions, and applying a working voltage between the anode and cathode, thereby achieving electrolytic hydrogen production.

[0017] The seventh aspect of the present application provides an electrolytic hydrogen production system, comprising an anode and a cathode, wherein the electrolytic hydrogen production system is used to electrolyze an aqueous solution containing chloride ions to produce hydrogen, and the anode comprises the electrolytic hydrogen production anode.

[0018] Compared with the prior art, this application has at least the following beneficial effects:

[0019] (1) The provided electrolytic hydrogen production catalyst provides a rich coordination environment for alkaline earth metal elements such as Ca, Sr, and Ba through the oxygen sites on the surface of hydrotalcite, so that they can be uniformly doped in the hydrotalcite in the form of atomic-level dispersion, wherein the alkaline earth metal element is preferably Ba; and, during the synthesis process, by controlling the addition amount of the alkaline earth metal element to 0.1 to 1 mmol / L, it can be ensured that the catalyst maintains excellent catalytic performance, and at an operating current of 400 mA / cm 2 In the three-electrode system, the voltage range is 1.52~1.55V.

[0020] (2) The provided electrolytic hydrogen production catalyst, by adding atomically dispersed doping elements, only requires a simple activation treatment. When applied to the electrolytic hydrogen production process of a chloride ion-containing aqueous solution, it not only maintains excellent catalytic performance with an anode catalytic selectivity of more than 99.7%, but also has significantly improved stability.

[0021] (3) The preparation process of the electrolytic hydrogen production catalyst provided is simple and can be achieved by a one-step solvent thermal reaction. The raw materials are cheap and easily available, making it suitable for large-scale production. It is of great significance to promote the promotion and application of seawater electrolysis hydrogen production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] FIG1 is an X-ray diffraction diagram of the electrolytic hydrogen production anode provided in Example 2.

[0024] FIG2 is an electron microscope photograph of the surface morphology of the electrolytic hydrogen production anode provided in Example 2.

[0025] FIG3 is a scanning transmission electron microscope photograph of the electrolytic hydrogen production anode provided in Example 2.

[0026] FIG4 is a spherical aberration transmission electron microscope photograph of the electrolytic hydrogen production anode provided in Example 2.

[0027] FIG5 is a graph showing the electrolysis stability test of the electrolysis hydrogen production anode provided in Example 2.

[0028] FIG6 is an X-ray photoelectron spectrum of the electrolytic hydrogen production anode provided in Example 4.

[0029] FIG7 is a graph showing the electrolytic stability test of the electrolytic hydrogen production anode provided in Example 5.

[0030] FIG8 is an electron microscope photograph of the surface morphology of the electrolytic hydrogen production anode provided in Example 5.

[0031] FIG9 is a graph showing the electrolytic stability test of the electrolytic hydrogen production anode provided in Example 5.

[0032] FIG10 is a graph showing the electrolytic stability test of the electrolytic hydrogen production anode provided in Example 6.

[0033] FIG11 is a graph showing the electrolytic stability test of the electrolytic hydrogen production anode provided in Example 7.

[0034] FIG12 is a graph showing the electrolytic stability test of the electrolytic hydrogen production anode provided in Example 8.

[0035] FIG13 is a graph showing the electrolysis stability test of the electrolysis hydrogen production anode provided in Comparative Example 1.

[0036] FIG14 is a graph showing the electrolysis stability test of the electrolysis hydrogen production anode provided in Comparative Example 2.

[0037] FIG15 is a graph showing the electrolysis stability test of the electrolysis hydrogen production anode provided in Comparative Example 3. DETAILED DESCRIPTION

[0038] In view of the shortcomings of the existing technology, the inventors of this case, after long-term research and extensive practice, have proposed the technical solution of this application. The following will further explain this technical solution, its implementation process and principles.

[0039] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0040] Furthermore, relational terms such as "first" and "second" are used merely to distinguish one substance or method step from another with the same name, but do not necessarily require or imply any actual relationship or order between these substances or method steps.

[0041] Some embodiments of the present application provide a catalyst for hydrogen production by electrolysis, the chemical formula of which is [M 1-x N x M'(OH)2] x+ [(A n- ) x / n mH2O] x- , M and N are any two ions of scandium, vanadium, chromium, manganese, iron, cobalt and nickel, and M and N are in the chemical valence state of +2 and +3 respectively, M' is selected from alkaline earth metal ions and is atomically dispersed in the catalyst, A n- Selected from CO3 2- 、NO3 2- 、Cl - , OH- or SO4 2- Wherein, x = 0.17 to 0.33. m is an integer greater than or equal to 0, preferably a natural number, and generally m decreases as x increases. n = 1 to 3. In some cases, m can be calculated according to the following formula, that is, m = (1-α×x / n), where α is A n- The number of positions occupied in the layered structure of the catalyst. In some cases, m can have a value of 1 to 9.

[0042] In one embodiment, the catalyst has at least one of the following characteristics:

[0043] ix) M and N are ions of any two of iron, cobalt, and nickel;

[0044] x)M' is selected from Ca 2+ 、Sr 2+ Or Ba 2+ ;

[0045] xi)A n- Selected from CO3 2- 、NO3 2- OH- or SO4 2- ;

[0046] xii) The atomic percentage content of M' in the catalyst is 0.4 to 0.5%.

[0047] Furthermore, the catalyst has at least one of the following characteristics:

[0048] 1)M' is Ba 2+ ;

[0049] 2)A n- Selected from CO3 2- or SO4 2- .

[0050] For example, M and N are Ni 2+ 、Fe 3+ , M' is Ba 2+ , A n- CO3 2- .

[0051] In this application, M' is preferably Ba 2+ For example, the catalyst is nickel-iron hydrotalcite doped with barium, wherein M and N are Ni 2+ 、Fe 3+ , and the atomic percentage content of barium in the catalyst is 0.4% to 0.5%. If the barium content is too low, it will result in less fixed sulfate ions and will not be able to fully protect the catalyst. Conversely, if the barium content is too high, it will have a negative impact on the catalytic performance.

[0052] In one embodiment, the catalyst has a nano-hexagonal platelet structure.

[0053] Furthermore, the nano hexagonal sheet structure has at least one of the following characteristics: a) a thickness of 100 to 200 nm; b) an area of ​​0.01 to 0.05 μm 2 .

[0054] Taking the catalyst as an example of nickel-iron hydrotalcite doped with barium, when the catalyst is used to prepare an anode and used for electrolysis of a chloride-containing aqueous solution to produce hydrogen, if the aqueous solution contains sulfate ions, the sulfate ions react with the barium ions in the catalyst to form barium sulfate, forming a fixed sulfate activation layer (hereinafter referred to as the sulfate activation layer or chlorine-exclusion layer) to expel chlorine, hindering the continued adsorption of other chloride ions in the solution on the catalyst surface, thereby delaying chloride ion corrosion, improving the stability of the catalyst and the corrosion resistance of the anode, and significantly extending the service life of the anode. At the same time, the appropriately doped barium and barium sulfate nanolayer structure does not substantially affect the catalytic activity of the catalyst. When the aqueous solution does not contain or contains less sulfate ions, the catalyst can be pre-activated with an alkaline sulfate solution to form the aforementioned sulfate activation layer on its surface, and then applied to the chloride-containing aqueous solution to produce hydrogen, similarly achieving the effect of improving the stability of the catalyst and the corrosion resistance of the anode, extending the service life of the anode.

[0055] Some embodiments of the present application also provide a method for preparing the electrolytic hydrogen production catalyst, which comprises: subjecting a mixed reaction solution containing M, N and M' to a hydrothermal reaction to obtain an electrolytic hydrogen production catalyst, wherein the chemical formula of the catalyst is [M 1-x N x M'(OH)2] x+ [(A n- ) x / n mH2O] x- , wherein M and N are any two ions of scandium, vanadium, chromium, manganese, iron, cobalt, and nickel, and M and N are in the chemical valence states of +2 and +3, respectively, M' is selected from alkaline earth metal ions and is atomically dispersed in the catalyst, A n- Selected from CO3 2- 、NO3 2- 、Cl - OH - or SO4 2- , the values ​​of x, m, and n are as shown above.

[0056] In one embodiment, the preparation method specifically includes: subjecting a mixed reaction liquid containing a first transition metal compound, a second transition metal compound and an alkaline earth metal compound in a molar ratio of 2-5:2-5:0.4-1 to a hydrothermal reaction at 90-120° C. to obtain the catalyst; wherein the first transition metal compound, the second transition metal compound and the alkaline earth metal compound contain M, N and M', respectively, and the pH value of the mixed reaction liquid is 8-10.

[0057] In one embodiment, the preparation method further specifically comprises:

[0058] Mixing the first transition metal compound, the second transition metal compound, the alkaline earth metal compound and water to form a metal salt solution, and adding an alkaline substance to adjust the pH value of the metal salt solution to 8-10, thereby obtaining the mixed reaction solution;

[0059] The mixed reaction liquid is reacted at 90-120° C. for 8-12 hours to prepare the catalyst.

[0060] In one embodiment, the first transition metal compound includes soluble nickel salts such as nickel nitrate and nickel chloride, the second transition metal compound includes soluble iron salts such as iron nitrate and iron chloride, and the alkaline earth metal compound includes soluble alkaline earth metal salts such as barium nitrate and barium chloride.

[0061] In one embodiment, the concentrations of the first transition metal compound, the second transition metal compound, and the alkaline earth metal compound in the mixed reaction solution are 0.1-1 mmol / L, 0.2-0.5 mmol / L, and 0.1-1 mmol / L, respectively.

[0062] In one embodiment, the alkaline substance includes any one or more combinations of urea, hexamethylenetetramethylenetetramethyleneamine, or triethanolamine, but is not limited thereto.

[0063] The preparation method of the electrolytic hydrogen production catalyst described in the present application can be achieved through a one-step solvent thermal reaction, which is simple to operate and does not require harsh reaction conditions such as high temperature and high pressure and expensive reaction equipment. In addition, the raw materials are mainly common metal salts, which are cheap and easy to obtain, low cost, and environmentally friendly.

[0064] Some embodiments of the present application also provide an activated electrolytic hydrogen production catalyst, which includes the electrolytic hydrogen production catalyst and a sulfate activation layer, wherein the sulfate activation layer includes sulfate ions distributed on the surface of the catalyst, and the sulfate ions are combined with the alkaline earth metal ions in the catalyst. Further, after the sulfate ions are combined with the alkaline earth metal ions, a nanolayer structure can be formed on the surface of the catalyst, and the nanolayer structure is mainly composed of nanoparticles with a particle size greater than 0 but less than 5nm. For example, if the alkaline earth metal ions are barium ions, the nanoparticles are barium sulfate nanoparticles.

[0065] Some embodiments of the present application also provide a method for activating a catalyst for hydrogen production by electrolysis, which comprises placing the catalyst in an alkaline solution containing sulfate ions and performing an activation treatment by an electrochemical method.

[0066] In one embodiment, the electrochemical method for activation includes but is not limited to cyclic voltammetry.

[0067] For example, the electrochemical method is cyclic voltammetry, wherein the scanning voltage used is 0V to 1V, the scanning voltage speed is 5mV / s to 50mV / s, and the number of scanning circles is 10 to 30 circles, so as to evenly distribute the aforementioned nanoparticles and avoid their agglomeration.

[0068] In one embodiment, the alkaline solution contains sulfate ions at a concentration of 0.01 to 0.1 mol / L, so that the aforementioned nanoparticles are small and evenly distributed, and do not affect the catalytic active area after covering the catalyst surface. That is, the formed sulfate active layer can both block the entry of chloride ions and leave sufficient channels for water molecules to contact the catalyst.

[0069] In one embodiment, the alkaline solution contains sulfate, which includes sodium sulfate or potassium sulfate, but is not limited thereto.

[0070] In one embodiment, the alkaline solution contains an alkaline substance with a concentration of 0.1 to 1 mol / L, wherein the alkaline substance may include but is not limited to sodium hydroxide or potassium hydroxide.

[0071] Some embodiments of the present application further provide an electrolytic hydrogen production anode, which includes the electrolytic hydrogen production catalyst or the activated electrolytic hydrogen production catalyst.

[0072] In one embodiment, a plurality of the catalyst nanosheets are vertically disposed on the surface of the anode and densely arranged to form an array structure.

[0073] In one embodiment, the specific surface area of ​​the array structure is 40 to 50 m 2 / g.

[0074] In one embodiment, the anode further includes a conductive substrate for supporting the catalyst, and the conductive substrate includes foamed nickel, nickel mesh, foamed iron, foamed nickel-iron, etc., but is not limited thereto.

[0075] In some cases, the conductive substrate can also be considered as the current collector of the anode.

[0076] Some embodiments of the present application also provide a method for preparing the electrolytic hydrogen production anode, comprising: placing the conductive substrate into the mixed reaction liquid comprising the first transition metal compound, the second transition metal compound and the alkaline earth metal compound in a molar ratio of 2-5:2-5:0.4-1, and performing a hydrothermal reaction at 90-120° C., thereby in situ generating the electrolytic hydrogen production catalyst on the conductive substrate.

[0077] Exemplarily, the method for preparing the electrolytic hydrogen production anode is to prepare the nickel iron barium hydrotalcite electrolytic hydrogen production anode by a one-step hydrothermal method, and the specific steps are as follows:

[0078] (1) A first transition metal compound, a second transition metal compound and an alkaline earth metal compound are mixed in a molar ratio of 2-5:2-5:0.4-1, and then an aqueous solution is added to obtain a metal salt solution, and an alkaline substance is added to adjust the pH to 8-10.

[0079] Preferably, the first transition metal compound comprises a nickel salt, and the second transition metal compound comprises an iron salt.

[0080] (2) Adding a conductive substrate to the above mixed solution, reacting at a temperature of 90-120° C. for 8-12 hours to obtain an anode material.

[0081] As some typical application examples, a solution prepared using nickel-iron hydrotalcite as a solvent can be used to slowly grow a densely coated catalyst in situ on a conductive substrate to serve as the anode for a comparative example; a solution prepared using nickel-iron-barium hydrotalcite as a solvent can be used to slowly grow a densely coated catalyst in situ on a conductive substrate. The prepared anode catalyst has excellent electrocatalytic seawater oxygen evolution performance and resistance to chlorine corrosion. Therefore, the anode can be used for catalytic electrolysis to produce hydrogen.

[0082] In the process of electrolytic hydrogen production without sulfate, the anode-loaded catalyst, namely nickel-iron-barium hydrotalcite, can be activated in a sulfate solution in advance to fix a sulfate layer on its surface. In the process of electrolytic hydrogen production with sulfate, sulfate ions in the solution react with barium in the hydrotalcite to generate barium sulfate, forming a fixed sulfate layer to expel chlorine, hindering the continued adsorption of other chloride ions in the solution on the electrode surface, thereby delaying the corrosion of the anode by chloride ions. In addition, the appropriate doping of barium and barium sulfate nanolayer structure will not have a significant impact on the catalytic effect of the anode, thereby improving the stability of the anode in the seawater electrolysis hydrogen production reaction.

[0083] Of course, the above technical solution may also include the steps of characterizing the material and testing the selectivity and stability of the anode after the seawater electrolysis hydrogen production is prepared. These steps may be for quality control or for in-depth research. Regardless of whether the characterization is performed and by what means, they are within the scope of protection of this application. The material characterization of the modified anode may include but is not limited to: X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) characterization to determine the material properties after coating; scanning electron microscopy (SEM), transmission electron microscopy (TEM) to characterize the material morphology, lattice and element content; the selectivity and stability of the modified anode may include but is not limited to: linear sweep voltammetry (LSV) and it constant current test.

[0084] The inventors discovered that the morphology, thickness, and layer coverage of the nickel-iron-barium nanosheets are key features for effectively removing chlorine without significantly negatively impacting catalytic efficiency. Achieving these characteristics requires uniquely designing the process parameters for depositing the nickel-iron-barium nanosheets to achieve this unique morphology. For example, during hydrothermal deposition, the solution concentration, hydrothermal temperature, and hydrothermal time are crucial. Only by setting the right deposition process can the unique nickel-iron-barium nanosheet morphology be achieved.

[0085] In one embodiment, the preparation method of the electrolytic hydrogen production anode includes uniformly doping barium in the anode by a hydrothermal method, wherein the hydrothermal solution used includes nickel salt, alkaline earth metal salt and iron salt in a molar ratio of 2 to 5:0.4 to 1:2 to 5, and additional alkaline substances, the alkaline earth metal salt includes but is not limited to barium nitrate, and the concentration of the alkaline earth metal salt in the hydrothermal solution is 0.1 to 1 mmol / L; the nickel salt includes but is not limited to nickel nitrate, and the concentration of the nickel salt in the hydrothermal solution is 0.1 to 1 mmol / L; the iron salt includes but is not limited to iron nitrate, and the concentration of the iron salt in the hydrothermal solution is 0.2 to 0.5 mmol / L; the alkaline substance includes but is not limited to any one or more of urea, hexamethylenetetramethylenetetramethylene or triethanolamine, and the concentration of the alkaline substance in the hydrothermal solution is 1 to 20 mmol / L.

[0086] The hydrothermal method can be performed at a temperature of 80 to 150° C., preferably 90 to 120° C., and for a time of 4 to 48 hours, preferably 8 to 12 hours. The hydrothermal method for co-depositing nickel iron barium comprises placing a conductive substrate in a hydrothermal solution and heating it, depositing barium ions in the solution onto the conductive substrate and dispersing them atomically into the catalyst.

[0087] In one embodiment, the method for preparing the electrolytic hydrogen anode specifically includes: immersing a conductive substrate in a hydrothermal solution, mixing and stirring to form the nickel-iron-barium hydrotalcite; the hydrothermal solution is prepared by dissolving an alkaline earth metal salt, a nickel salt, and an iron salt, as well as an additional alkaline substance, in water, and the amount of water used is 35 to 50 mL; the mixing and stirring is performed at a speed of 800 to 1200 rpm.

[0088] In summary, it can be seen that the above-mentioned preferred hydrothermal method is different from the existing preparation process of hydrothermal nickel-iron hydrotalcite anode. For example, its barium salt concentration and the concentration ratio of nickel salt and iron salt are different from those of the existing preparation process of hydrothermal nickel-iron hydrotalcite anode. This is a change made to form the above-mentioned nanolayer structure.

[0089] In one embodiment, a method for activating an electrolytic hydrogen production anode includes activating the electrolytic hydrogen production anode in an alkaline solution containing sulfate.

[0090] Specifically, the electrolytic hydrogen production anode activation method includes activating the electrolytic hydrogen production anode using cyclic voltammetry in a sulfate solution. The solution used in the cyclic voltammetry method includes an alkaline substance and a sulfate salt. The alkaline substance includes sodium hydroxide or potassium hydroxide, and the sulfate salt may include sodium sulfate, but is not limited thereto. The concentration of the alkaline substance in the solution is 0.1 to 1 mol / L, and the concentration of the sulfate is 0.01 to 0.1 mol / L.

[0091] The test system used in the cyclic voltammetry method can be a three-electrode system, the counter electrode used is a carbon rod, and the reference electrode used is a silver / silver chloride electrode; the ambient temperature used in the cyclic voltammetry method is 20-25°C, the number of scan cycles used is 10-30 cycles, the scan voltage range used is 0V-1V, and the scan voltage rate used is 5mV / s-50mV / s.

[0092] In summary, it can be seen that the above-mentioned preferred activation method is a unique activation method of the present application. Its scanning voltage rate, scanning voltage range and electrode system are different from the existing anode activation process. This is a change made to fix the above-mentioned sulfate activation layer.

[0093] Some embodiments of the present application also provide applications of the electrolytic hydrogen production catalyst, the activated electrolytic hydrogen production catalyst, or the electrolytic hydrogen production anode in electrolytic hydrogen production.

[0094] In one embodiment, the application includes placing the electrolytic hydrogen production anode and cathode into an aqueous solution containing chloride ions, and applying a working voltage between the anode and cathode.

[0095] Some embodiments of the present application also provide an application of the electrolytic hydrogen production catalyst in electrolytic hydrogen production, wherein the application includes: placing an electrolytic hydrogen production anode and a cathode in an aqueous solution containing chloride ions and sulfate ions, and applying an operating voltage between the anode and the cathode to achieve electrolytic hydrogen production; the anode includes the electrolytic hydrogen production catalyst.

[0096] Some embodiments of the present application also provide a method for producing hydrogen by electrolysis, comprising: placing the electrolytic hydrogen production anode and cathode in an aqueous solution containing chloride ions, and applying a working voltage between the anode and cathode, thereby achieving electrolytic hydrogen production.

[0097] In one embodiment, the aqueous solution containing chloride ions includes but is not limited to seawater or chlorine-containing industrial wastewater, etc. Preferably, the aqueous solution containing chloride ions is alkaline.

[0098] Taking the aqueous solution containing chloride ions as seawater as an example, the electrolysis method for producing hydrogen is used at a temperature of 25°C, a voltage of 2V, a distance between the anode and the cathode of 1cm, and an anode surface area of ​​1cm. 2Under the conditions of , the hydrogen evolution efficiency can reach more than 0.27L / hour.

[0099] Some embodiments of the present application also provide an electrolytic hydrogen production system, comprising an anode and a cathode, wherein the electrolytic hydrogen production system is used to produce hydrogen by electrolysis of an aqueous solution containing chloride ions, and the anode comprises the electrolytic hydrogen production anode.

[0100] In one embodiment, the aqueous solution containing chloride ions includes but is not limited to seawater or chlorine-containing industrial wastewater. In specific implementation, for cost considerations, the optimal choice of the aqueous solution containing chloride ions is seawater.

[0101] In some cases, the electrolytic hydrogen production system may further include a power supply, etc. The cathode may be made of Pt, Ni, RaneyNi, NiMo alloy, etc.

[0102] This application provides a new idea for improving the stability of the anode during seawater electrolysis to produce hydrogen.

[0103] The technical solution of the present application is further described in detail below through several examples and in combination with the accompanying drawings. However, the selected examples are only used to illustrate the present application and do not limit the scope of the present application. Also, unless otherwise specified, the raw materials, detection reagents and detection equipment used in the following examples can be purchased from the market, and the detection methods used are also commonly used in the art. For example, the nickel foam used below is commercial nickel foam, and it is cleaned before use. The specific cleaning method includes: cutting the commercial nickel foam into 1cm×4cm strips, and rinsing in 2mol·L -1 The samples were ultrasonically treated in a hydrochloric acid solution for 3 min, and then ultrasonically cleaned in deionized water and anhydrous ethanol three times respectively, and then dried naturally in air.

[0104] Example 1

[0105] (1) Nickel nitrate hexahydrate, barium nitrate, iron nitrate nonahydrate, and hexamethylenetetraammonium were weighed and dissolved in 35 mL of deionized water in a molar ratio of 5:0.5:5:10 to prepare a solvent-thermal reaction solution containing nickel, iron, and barium. The solution was then transferred to a 50 mL polytetrafluoroethylene reaction vessel.

[0106] (2) Using nickel foam as a conductive substrate, the cleaned conductive substrate was immersed in the reaction solution, sealed in a stainless steel autoclave, and subjected to a solvent-thermal reaction at 80°C for 48 hours. After cooling, the substrate was removed from the autoclave and cleaned with ultrapure water and ethanol. The substrate was then placed in an oven and dried in air at 60°C for 12 hours. This resulted in a highly stable NiFeBa / NF oxygen evolution anode (hereinafter also referred to as the NiFeBa / NF anode or electrolytic hydrogen production anode).

[0107] (3) Weigh 20 g of sodium hydroxide and 146.1 g of sodium chloride and dissolve them in 1 L of deionized water to prepare a low-alkali, high-salt concentration simulated seawater solution containing 0.5 M NaOH and 2.5 M NaCl.

[0108] (4) The NiFeBa / NF anode prepared in step (2) was used as the working electrode, the platinum sheet was used as the counter electrode, and the low-alkali high-salt concentration simulated seawater in step (3) was used as the electrolyte. 2 The stability of NiFeBa / NF was tested at a current density of .

[0109] As a control, the barium nitrate in step (1) was omitted, and the remaining operations and process conditions were the same as steps (1) to (2), and finally a NiFe-LDH / NF anode was prepared. Then, its stability was tested in the same manner as step (4).

[0110] Test results show that the NiFeBa / NF anode prepared in this example maintains stability for about 2 hours in harsh simulated seawater electrolysis, while the NiFe-LDH / NF anode can only operate for 30 minutes in the same solution environment, indicating that the NiFeBa / NF anode prepared in this example plays a role in protecting the conductive substrate.

[0111] Example 1-1

[0112] The preparation method of a NiFeBa / NF anode provided in this embodiment is basically the same as that in Example 1, except that the reaction temperature of the solvent thermal reaction in step (2) is 90° C. and the reaction time is 12 h.

[0113] The stability of the NiFeBa / NF anode of this embodiment was tested using the same method as in Example 1. The test results showed that the stability of the NiFeBa / NF anode prepared in this embodiment was maintained for about 3 hours in harsh simulated seawater electrolysis.

[0114] Example 2

[0115] (1) Nickel nitrate hexahydrate, barium nitrate, iron nitrate nonahydrate, and urea were weighed and dissolved in 35 mL of deionized water in a molar ratio of 3:0.6:1:6 to prepare a solvent-thermal reaction solution containing nickel, iron, and barium. The solution was then transferred to a 50 mL polytetrafluoroethylene reaction vessel.

[0116] (2) Using nickel foam as a conductive substrate, the cleaned conductive substrate was immersed in the reaction solution, sealed in a stainless steel high-pressure reactor, and subjected to solvent thermal reaction at 150°C for 4 hours. After cooling and removal, it was cleaned with ultrapure water and ethanol, placed in an oven, and dried in air at 60°C for 12 hours to prepare a NiFeBa / NF anode. The X-ray diffraction pattern of the NiFeBa / NF anode is shown in Figure 1, the surface morphology is shown in Figure 2, and the TEM images are shown in Figures 3 and 4. It can be clearly seen that: on the one hand, NiFeBa is tightly covered on the surface of the conductive substrate, and on the other hand, barium is doped in the nickel-iron hydrotalcite in an atomically dispersed form to form a new anode nickel-iron-barium hydrotalcite. The XPS graph is shown in Figure 6.

[0117] (3) Weigh 40 g of sodium hydroxide and 146.1 g of sodium chloride solid and dissolve them in 1 L of deionized water to prepare a simulated seawater solution containing 1 M NaOH and 2.5 M NaCl.

[0118] (4) The NiFeBa / NF anode prepared in step (2) was used as the working electrode, the platinum sheet was used as the counter electrode, and the high concentration simulated seawater prepared in step (3) was used as the electrolyte. 2 The stability of the NiFeBa / NF anode was tested at a current density of , and the results are shown in Figure 5.

[0119] As a control, the barium nitrate in step (1) was omitted, and the remaining operations and process conditions were the same as steps (1) to (2), and finally a NiFe-LDH / NF anode was prepared. Then, its stability was tested in the same manner as step (4).

[0120] The electrode prepared in this example worked stably for up to 120 hours in simulated seawater electrolysis, and its stability was approximately four times that of NiFe-LDH / NF, indicating that the NiFeBa / NF anode prepared in this example played a protective role for the substrate.

[0121] Example 2-1

[0122] The preparation method of a NiFeBa / NF anode provided in this embodiment is basically the same as that in Example 2, except that the reaction temperature of the solvent thermal reaction in step (2) is 120° C. and the time is 4 h.

[0123] The stability of the NiFeBa / NF anode of this embodiment was tested using the same method as in Example 2. The test results showed that the stability of the NiFeBa / NF anode prepared in this embodiment was maintained for about 140 hours in simulated seawater electrolysis.

[0124] Example 3

[0125] (1) Nickel nitrate hexahydrate, barium nitrate, iron nitrate nonahydrate, and urea were weighed and dissolved in 35 mL of deionized water in a molar ratio of 3:1:3:10 to prepare a nickel-iron-barium solvent thermal reaction solution, which was then transferred to a 50 mL polytetrafluoroethylene reaction tank.

[0126] (2) Using nickel foam as a conductive substrate, the cleaned conductive substrate was immersed in the reaction solution, sealed in a stainless steel high-pressure reactor and subjected to solvent thermal reaction at 120°C for 24 hours. After cooling and taking out, it was cleaned with ultrapure water and ethanol, placed in an oven, and dried in air at 60°C for 12 hours to obtain a NiFeBa / NF anode.

[0127] (3) Weigh 20 g of sodium hydroxide, 146.1 g of sodium chloride, and 35.51 g of anhydrous sodium sulfate solid and dissolve them in 1 L of deionized water to prepare a high-concentration simulated seawater solution containing 0.5 M NaOH, 2.5 M NaCl, and 0.25 M Na2SO4.

[0128] (4) The NiFeBa / NF anode prepared in step (2) was used as the working electrode, the platinum sheet was used as the counter electrode, and the low-alkali high-salt concentration simulated seawater in step (3) was used as the electrolyte. 2 The stability of NiFeBa / NF anode was tested at a current density of .

[0129] As a control, the barium nitrate in step (1) was omitted, and the remaining operations and process conditions were the same as steps (1) to (2), and finally a NiFe-LDH / NF anode was prepared. Then, its stability was tested in the same manner as step (4).

[0130] The electrode prepared in this example has a stable working time of up to 18 hours in seawater electrolysis, and its stability is about 8 times that of NiFe-LDH / NF, indicating that the NiFeBa / NF anode prepared in this example plays a role in protecting the substrate.

[0131] Example 3-1

[0132] The preparation method of a NiFeBa / NF anode provided in this embodiment is basically the same as that in Example 2, except that the reaction temperature of the solvent thermal reaction in step (2) is 120° C. and the time is 4 h.

[0133] The stability of the NiFeBa / NF anode of this embodiment was tested using the same method as in Example 3. The test results showed that the stability of the NiFeBa / NF anode prepared in this embodiment was maintained for about 25 hours in simulated seawater electrolysis.

[0134] Example 4

[0135] (1) Nickel nitrate hexahydrate, barium nitrate, iron nitrate nonahydrate, and urea were weighed and dissolved in 35 mL of deionized water at a molar ratio of 5:0.5:5:10 to prepare a solvent-thermal reaction solution containing nickel, iron, and barium, and the solution was transferred to a 50 mL polytetrafluoroethylene reaction tank.

[0136] (2) Nickel foam was used as the conductive substrate, and the cleaned conductive substrate was immersed in the reaction solution, sealed in a stainless steel high-pressure reactor and subjected to solvent thermal reaction at 120°C for 24 hours. After cooling and taking out, it was cleaned with ultrapure water and ethanol, placed in an oven, and dried in air at 60°C for 12 hours to obtain a highly stable NiFeBa / NF anode.

[0137] (3) Weigh 20 g of sodium hydroxide, 146.1 g of sodium chloride, and 35.51 g of anhydrous sodium sulfate solid and dissolve them in 1 L of deionized water to prepare a high-concentration simulated seawater solution containing 0.5 M NaOH, 2.5 M NaCl, and 0.25 M Na2SO4.

[0138] (4) The NiFeBa / NF anode prepared in step (2) was used as the working electrode, the platinum sheet was used as the counter electrode, and the low-alkali high-salt concentration simulated seawater in step (3) was used as the electrolyte. 2 The stability of the NiFeBa / NF anode was tested at a current density of , and the results are shown in Figure 7.

[0139] As a control, the barium nitrate in step (1) was omitted, and the remaining operations and process conditions were the same as steps (1) to (2), and finally a NiFe-LDH / NF anode was prepared. Then, its stability was tested in the same manner as step (4).

[0140] The NiFeBa / NF anode prepared in this example has a stable working time of up to 20 hours in seawater electrolysis, and its stability is about seven times that of NiFe-LDH / NF, indicating that the NiFeBa / NF anode prepared in this example plays a role in protecting the substrate.

[0141] Based on the above examples, it can be seen that within a suitable barium nitrate concentration range, the stability of the prepared NiFeBa / NF anode is greatly improved compared to that of NiFe-LDH / NF.

[0142] Example 5

[0143] (1) Nickel nitrate hexahydrate, barium nitrate, iron nitrate nonahydrate, and urea were weighed and dissolved in 35 mL of deionized water at a molar ratio of 4:1:4:8 to prepare a solvent-thermal reaction solution containing nickel, iron, and barium. The solution was then transferred to a 50 mL polytetrafluoroethylene reaction tank.

[0144] (2) Using nickel foam as a conductive substrate, the cleaned conductive substrate was immersed in the reaction solution and sealed in a stainless steel autoclave for a 4-hour solvothermal reaction at 150°C. After cooling, the substrate was removed and cleaned with ultrapure water and ethanol. The substrate was then placed in an oven and dried in air at 60°C for 12 hours. A highly stable NiFeBa / NF anode was obtained, as shown in the scanning image in Figure 8, showing that the NiFeBa / NF was tightly covered on the surface of the conductive substrate.

[0145] (3) Weigh 40 g of sodium hydroxide, 146.1 g of sodium chloride, and 35.51 g of anhydrous sodium sulfate solid and dissolve them in 1 L of deionized water to prepare a high-concentration simulated seawater solution containing 1 M NaOH, 2.5 M NaCl, and 0.25 M Na2SO4.

[0146] (4) The NiFeBa / NF prepared in step (2) was used as the working electrode, the platinum sheet was used as the counter electrode, and the high concentration simulated seawater prepared in step (3) was used as the electrolyte. 2 The stability of NiFeBa / NF was tested at a current density of , and the results are shown in Figure 9.

[0147] As a control, the barium nitrate in step (1) was omitted, and the remaining operations and process conditions were the same as steps (1) to (2), and finally a NiFe-LDH / NF anode was prepared. Then, its stability was tested in the same manner as step (4).

[0148] The NiFeBa / NF anode prepared in this example has a stable working time of more than 600 hours in seawater electrolysis, while the NiFe-LDH / NF anode can only operate for 60 hours, indicating that the NiFeBa / NF anode prepared in this example plays a role in protecting the substrate.

[0149] Example 5-1

[0150] The preparation method of a NiFeBa / NF anode provided in this embodiment is basically the same as that in Example 2, except that the reaction temperature of the solvent thermal reaction in step (2) is 100° C. and the time is 4 hours.

[0151] The stability of the NiFeBa / NF anode of this embodiment was tested using the same method as in Example 5. The test results showed that the stability of the NiFeBa / NF anode prepared in this embodiment was maintained for about 630 hours in simulated seawater electrolysis.

[0152] Example 5-2

[0153] The preparation method of a NiFeCa / NF anode provided in this embodiment is basically the same as that in Example 5, except that the barium nitrate used in step (1) is replaced by calcium nitrate.

[0154] The stability of the NiFeCa / NF anode of this embodiment was tested using the same method as in Example 5. The test results showed that the stability of the NiFeCa / NF anode prepared in this embodiment was maintained for about 530 hours in simulated seawater electrolysis.

[0155] Example 5-3

[0156] The preparation method of a NiFeSr / NF anode provided in this embodiment is basically the same as that in Example 5, except that strontium nitrate is used instead of barium nitrate used in step (1).

[0157] The stability of the NiFeSr / NF anode of this embodiment was tested using the same method as in Example 5. The test results showed that the stability of the NiFeSr / NF anode prepared in this embodiment was maintained for about 560 hours in simulated seawater electrolysis.

[0158] Example 6

[0159] (1) Nickel nitrate hexahydrate, barium nitrate, iron nitrate nonahydrate, and urea were weighed and dissolved in 35 mL of deionized water at a molar ratio of 4:0.4:4:6 to prepare a solvent-thermal reaction solution containing nickel, iron, and barium. The solution was then transferred to a 50 mL polytetrafluoroethylene reaction tank.

[0160] (2) Using nickel foam as a conductive substrate, the cleaned conductive substrate was immersed in the reaction solution, sealed in a stainless steel high-pressure reactor and subjected to solvent thermal reaction at 80°C for 48 hours. After cooling and taking out, it was cleaned with ultrapure water and ethanol, placed in an oven, and dried in air at 60°C for 12 hours to obtain a highly stable NiFeBa / NF anode.

[0161] (3) Weigh 40 g of sodium hydroxide and 29.22 g of sodium chloride solid and dissolve them in 1 L of deionized water to prepare a simulated seawater solution containing 1 M NaOH and 0.5 M NaCl.

[0162] (4) The NiFeBa / NF anode prepared in step (2) was used as the working electrode, the platinum sheet was used as the counter electrode, and the simulated seawater prepared in step (3) was used as the electrolyte. 2 The stability of NiFeBa / NF was tested at a current density of , and the results are shown in Figure 10.

[0163] As a control, the barium nitrate in step (1) was omitted, and the remaining operations and process conditions were the same as steps (1) to (2), and finally a NiFe-LDH / NF anode was prepared. Then, its stability was tested in the same manner as step (4).

[0164] The NiFeBa / NF anode prepared in this example has a stable working time of up to 500 hours in seawater electrolysis, and its stability is approximately twice that of NiFe-LDH / NF. This shows that the NiFeBa / NF anode prepared in this example has a certain degree of improvement in protecting the substrate without adding sulfate.

[0165] Example 6-1

[0166] The preparation method of a NiFeBa / NF anode provided in this embodiment is basically the same as that in Example 2, except that the reaction temperature of the solvent thermal reaction in step (2) is 90° C. and the reaction time is 12 h.

[0167] The stability of the NiFeBa / NF anode of this embodiment was tested using the same method as in Example 6. The test results showed that the stability of the NiFeBa / NF anode prepared in this embodiment was maintained for about 550 hours in simulated seawater electrolysis.

[0168] Example 7

[0169] (1) Nickel nitrate hexahydrate, barium nitrate, iron nitrate nonahydrate, and urea were weighed and dissolved in 35 mL of deionized water at a molar ratio of 5:1:1.5:10 to prepare a solvent-thermal reaction solution containing nickel, iron, and barium. The solution was then transferred to a 50 mL polytetrafluoroethylene reaction tank.

[0170] (2) Nickel foam was used as the conductive substrate, and the cleaned conductive substrate was immersed in the reaction solution, sealed in a stainless steel high-pressure reactor and subjected to solvent thermal reaction at 120°C for 24 hours. After cooling and taking out, it was cleaned with ultrapure water and ethanol, placed in an oven, and dried in air at 60°C for 12 hours to obtain a highly stable NiFeBa / NF anode.

[0171] (3) Weigh 40 g of sodium hydroxide, 29.22 g of sodium chloride, and 7.1 g of sodium sulfate solids and dissolve them in 1 L of deionized water to prepare a simulated seawater solution containing 1 M NaOH, 0.5 M NaCl, and 0.05 M Na2SO4.

[0172] (4) The NiFeBa / NF anode prepared in step (2) was used as the working electrode, the platinum sheet was used as the counter electrode, and the simulated seawater prepared in step (3) was used as the electrolyte. 2 The stability of NiFeBa / NF was tested at a current density of , and the results are shown in Figure 11.

[0173] As a control, the barium nitrate in step (1) was omitted, and the remaining operations and process conditions were the same as steps (1) to (2), and finally a NiFe-LDH / NF anode was prepared. Then, its stability was tested in the same manner as step (4).

[0174] The NiFeBa / NF anode prepared in this example has been stably operated for 4000 hours in seawater electrolysis. Its stability is currently about three times that of NiFe-LDH / NF, indicating that the NiFeBa / NF anode prepared in this example has excellent stability.

[0175] Example 8

[0176] (1) Nickel nitrate hexahydrate, barium nitrate, iron nitrate nonahydrate, and urea were weighed and dissolved in 35 mL of deionized water at a molar ratio of 2:0.6:2:6 to prepare a solvent-thermal reaction solution containing nickel, iron, and barium. The solution was then transferred to a 50 mL polytetrafluoroethylene reaction vessel.

[0177] (2) Using nickel foam as a conductive substrate, the cleaned conductive substrate was immersed in the reaction solution and sealed in a stainless steel autoclave for a solvent thermal reaction at 120°C for 24 hours. After cooling, the substrate was taken out and cleaned with ultrapure water and ethanol. The substrate was placed in an oven and dried in air at 60°C for 12 hours. A highly stable NiFeBa / NF anode was obtained.

[0178] (3) Weigh 40g of sodium hydroxide and 142.04g of anhydrous sodium sulfate solid and dissolve them in 1L of deionized water to prepare an electrolyte solution containing 1M NaOH and 1M Na2SO4. The NiFeBa / NF prepared in step (2) is used as the working electrode and the platinum sheet is used as the counter electrode. The electrolyte solution containing 1M NaOH and 1M Na2SO4 is used at 400mA / cm 2 The NiFeBa / NF anode was activated at a current density of 1 h to obtain an activated NiFeBa / NF anode.

[0179] (4) Weigh 40 g of sodium hydroxide and 146.1 g of sodium chloride solid and dissolve them in 1 L of deionized water to prepare a high-concentration simulated seawater solution containing 1 M NaOH and 2.5 M NaCl.

[0180] (5) The activated NiFeBa / NF anode prepared in step (3) was used as the working electrode, the platinum sheet was used as the counter electrode, and the high concentration simulated seawater prepared in step (4) was used as the electrolyte. 2 The stability of the NiFeBa / NF anode was tested at a current density of , and the results are shown in Figure 12.

[0181] The activated NiFeBa / NF anode prepared in this example has a stable working time of up to 310 hours in seawater electrolysis, while the NiFe-LDH / NF anode can only operate for 30 hours, indicating that the activated NiFeBa / NF anode prepared in this example plays a role in protecting the substrate.

[0182] As a control, if the above step (3) is omitted and the NiFeBa / NF anode of step (2) is directly tested in step (5), the results show that, without activation, the activated NiFeBa / NF anode prepared in this embodiment has a stable working time of 30 hours in a high-concentration simulated seawater solution of 1M NaOH and 2.5M NaCl.

[0183] Comparative Example 1

[0184] (1) Nickel nitrate hexahydrate, iron nitrate nonahydrate, and urea were weighed and dissolved in 35 mL of deionized water at a molar ratio of 5:5:10 to prepare a nickel-iron solvent thermal reaction solution, which was then transferred to a 50 mL polytetrafluoroethylene reaction tank.

[0185] (2) Using nickel foam as a conductive substrate, the cleaned conductive substrate was immersed in the reaction solution, sealed in a stainless steel high-pressure reactor, and subjected to solvent thermal reaction at 120°C for 24 hours. After cooling and taking out, it was cleaned with ultrapure water and ethanol, placed in an oven, and dried in air at 60°C for 12 hours to obtain a NiFe-LDH / NF anode.

[0186] (3) Weigh 40 g of sodium hydroxide and 146.1 g of sodium chloride solid and dissolve them in 1 L of deionized water to prepare a simulated seawater solution containing 1 M NaOH and 2.5 M NaCl.

[0187] (4) The NiFe-LDH / NF prepared in step (2) was used as the working electrode, the platinum sheet was used as the counter electrode, and the simulated seawater prepared in step (3) was used as the electrolyte. 2 The stability of the NiFe-LDH / NF anode was tested at a current density of 1.5 Å, with the results shown in Figure 13. The NiFe-LDH / NF anode prepared in this comparative example was stable for approximately 30 hours, demonstrating activity comparable to the control NiFeBa / NF anode, but with inferior stability. The control NiFeBa / NF anode was prepared using essentially the same method as Example 4, differing only in that the hydrothermal reaction temperature was 120°C.

[0188] Comparative Example 2

[0189] (1) Weigh nickel nitrate hexahydrate, iron nitrate nonahydrate, and urea in a molar ratio of 5:5:10 and dissolve them in 35 mL of deionized water to prepare a nickel-iron solvent thermal reaction solution, which is then transferred to a 50 mL polytetrafluoroethylene reaction tank.

[0190] (2) Using nickel foam as a conductive substrate, the cleaned conductive substrate was immersed in the reaction solution and sealed in a stainless steel autoclave for a solvent thermal reaction at 150°C for 4 hours. After cooling, the substrate was taken out and cleaned with ultrapure water and ethanol. The substrate was placed in an oven and dried in air at 60°C for 12 hours to obtain a NiFe-LDH / NF anode.

[0191] (3) Weigh 40 g of sodium hydroxide and 29.22 g of sodium chloride solid and dissolve them in 1 L of deionized water to prepare a simulated seawater solution containing 1 M NaOH and 0.5 M NaCl.

[0192] (4) The NiFe-LDH / NF anode prepared in step (5) was used as the working electrode, the platinum sheet was used as the counter electrode, and the simulated seawater prepared in step (3) was used as the electrolyte. 2 The stability of NiFe-LDH / NF was tested at a current density of 1.5 Å, and the results are shown in Figure 14. The stability of the NiFe-LDH / NF anode prepared in this comparative example was poor, about 230 hours, which was much lower than the NiFeBa / NF anode in Example 4 above.

[0193] Comparative Example 3

[0194] (1) Weigh nickel nitrate hexahydrate, iron nitrate nonahydrate, and urea in a molar ratio of 5:5:10 and dissolve them in 35 mL of deionized water to prepare a nickel-iron solvent thermal reaction solution, which is then transferred to a 50 mL polytetrafluoroethylene reaction tank.

[0195] (2) Using nickel foam as a conductive substrate, the cleaned conductive substrate was immersed in the reaction solution, sealed in a stainless steel high-pressure reactor, and subjected to solvent thermal reaction at 90°C for 48 hours. After cooling and removal, it was cleaned with ultrapure water and ethanol, placed in an oven, and dried in air at 60°C for 12 hours to obtain a NiFeBa / NF anode.

[0196] (3) Weigh 40 g of sodium hydroxide, 29.22 g of sodium chloride, and 7.1 g of sodium sulfate solids and dissolve them in 1 L of deionized water to prepare a simulated seawater solution containing 1 M NaOH, 0.5 M NaCl, and 0.05 M Na2SO4.

[0197] (4) The NiFe-LDH / NF anode prepared in step (2) was used as the working electrode, the platinum sheet was used as the counter electrode, and the simulated seawater prepared in step (3) was used as the electrolyte. 2 The stability of the NiFe-LDH / NF anode was tested at a current density of , and the results are shown in Figure 15. The stability of the NiFe-LDH / NF anode prepared in this comparative example was poor, about 800 hours, which was much lower than the NiFeBa / NF anode in Example 4 above.

[0198] At a temperature of 25°C, a voltage of 2V, a distance between the anode and cathode of 1cm, and an anode surface area of ​​1cm 2 Under the same conditions, the simulated seawater in Example 7 was electrolyzed using the anodes of Examples 1 to 8 to produce hydrogen, with hydrogen evolution efficiencies of 0.272, 0.268, 0.271, 0.265, 0.267, 0.270, 0.273, and 0.266 L / hour, respectively. Under the same conditions, the simulated seawater in Example 1 was electrolyzed using the anodes of Comparative Examples 1 to 3 to produce hydrogen, with hydrogen evolution efficiencies of 0.257, 0.251, and 0.254 L / hour, respectively.

[0199] In addition, the inventors also prepared NiFeBa / NF anodes using commercial nickel mesh, commercial foam iron, and commercial foam nickel-iron as conductive substrates instead of the nickel foam in Examples 1 to 8, and tested the stability and electrolytic hydrogen production efficiency of these NiFeBa / NF anodes using the same test methods as Examples 1 to 8. The test results showed that these NiFeBa / NF anodes all exhibited excellent stability and high electrolytic hydrogen production efficiency.

[0200] Example 9 The preparation method of a NiFeCa / NF anode is basically the same as that of Example 3, except that barium nitrate is replaced by calcium nitrate.

[0201] Example 9-1 The preparation method of a NiFeCa / NF anode is basically the same as that of Example 3-1, except that barium nitrate is replaced by calcium nitrate.

[0202] Example 10 The preparation method of a NiFeSr / NF anode is basically the same as that of Example 3, with the only difference being that barium nitrate is replaced by strontium nitrate.

[0203] Example 10-1 The preparation method of a NiFeSr / NF anode is basically the same as that of Example 3-1, with the only difference being that barium nitrate is replaced by strontium nitrate.

[0204] The anode performance of Examples 9, 9-1, 10, and 10-1 was tested with reference to the methods of Example 3 and Example 3-1. The results are shown in Table 1 below.

[0205] Table 1 Anode performance test results of Examples 9, 9-1, 10, and 10-1

[0206] Based on the above embodiments, it can be seen that the electrode hydrogen production catalyst provided in the present application enables the surface of the electrode hydrogen production anode to have higher resistance to chloride ions, which can significantly delay the corrosion of chloride ions on the conductive substrate and catalyst in seawater electrolysis, thereby making the anode have excellent stability in the process of electrolysis hydrogen production in chlorine-containing aqueous solution, especially in the electrolysis hydrogen production reaction in seawater.

[0207] The above-mentioned embodiments of the present application prepare NiFeBa / NF, NiFeCa / NF, NiFeSr / NF oxygen evolution catalysts densely coated on a conductive substrate through a simple hydrothermal method, using non-precious metals as the catalyst metal source, which has the advantage of low cost and significantly extends the service life of the electrolytic hydrogen production anode.

[0208] It should be understood that the above embodiments are merely illustrative of the technical concepts and features of this application. Their purpose is to enable those familiar with the art to understand the content of this application and implement it accordingly. They are not intended to limit the scope of protection of this application. Any equivalent changes or modifications made in accordance with the spirit and substance of this application shall be included within the scope of protection of this application.

Claims

1. A catalyst for hydrogen production by electrolysis, characterized in that: The chemical formula of the catalyst is [M 1-x N x M'(OH)2] x+ [(A n- ) x / n .mH2O] x- , M and N are any two ions of scandium, vanadium, chromium, manganese, iron, cobalt and nickel, and M and N are in chemical valence states of +2 and +3, respectively, M' is selected from alkaline earth metal ions and is atomically dispersed in the catalyst, A n- Selected from CO3 2- 、NO3 2- , Cl - OH - or SO4 2- , x=0.17~0.33, m is an integer greater than or equal to 0, and n=1~3.

2. The electrolytic hydrogen production catalyst according to claim 1, characterized in that The catalyst has at least one of the following characteristics: i) M and N are any two ions of iron, cobalt and nickel; ii) M' is selected from Ca 2+ , Sr 2+ Or Ba 2+ ; iii) A n- Selected from CO3 2- 、NO3 2- OH - or SO4 2- ; iv) the atomic percentage content of M' in the catalyst is 0.4% to 0.5%; Preferably, the catalyst has at least one of the following characteristics: 1) M' is Ba 2+ ; 2) A n- Selected from CO3 2- or SO4 2- ; and / or, M and N are Ni 2+ , Fe 3+ , M' is Ba 2+ , A n- For CO3 2- ; And / or, the catalyst has a nano hexagonal sheet structure; preferably, the nano hexagonal sheet structure has at least one of the following characteristics: a) a thickness of 100 to 200 nm; b) an area of ​​0.01 to 0.05 μm 2 .

3. A method for preparing a catalyst for hydrogen production by electrolysis, characterized in that: include: The mixed reaction liquid containing M, N and M' is subjected to a hydrothermal reaction to obtain an electrolytic hydrogen production catalyst, wherein the chemical formula of the catalyst is [M 1-x N x M'(OH)2] x+ [(A n- ) x / n ·mH2O] x- , wherein M and N are any two ions of scandium, vanadium, chromium, manganese, iron, cobalt, and nickel, and M and N are in the chemical valence states of +2 and +3, respectively, M' is selected from alkaline earth metal ions and is atomically dispersed in the catalyst, A n- Selected from CO3 2- 、NO3 2- , Cl - , OH- or SO4 2- , x=0.17~0.33, m is an integer greater than or equal to 0, and n=1~3.

4. The preparation method according to claim 3, characterized in that: Specifically include: The catalyst is prepared by subjecting a mixed reaction liquid containing a first transition metal compound, a second transition metal compound and an alkaline earth metal compound in a molar ratio of 2-5:2-5:0.4-1 to a hydrothermal reaction at 90-120° C., wherein the first transition metal compound, the second transition metal compound and the alkaline earth metal compound contain M, N and M′ respectively, and the pH value of the mixed reaction liquid is 8-10.

5. The preparation method according to claim 4, characterized in that: Specifically include: The first transition metal compound, the second transition metal compound, the alkaline earth metal compound and water are mixed to form a metal salt solution, and an alkaline substance is added to adjust the pH value of the metal salt solution to 8-10, thereby obtaining the mixed reaction solution; The mixed reaction liquid is reacted at 90-120° C. for 8-12 hours to obtain the catalyst.

6. The preparation method according to any one of claims 4 to 5, characterized in that The catalyst has at least one of the following characteristics: i) M and N are any two ions of iron, cobalt and nickel; ii) M' is selected from Ca 2+ , Sr 2+ Or Ba 2+ ; iii) A n- Selected from CO3 2- 、NO3 2- , OH- or SO4 2- ; iv) the atomic percentage content of M' in the catalyst is 0.4% to 0.5%; Preferably, the catalyst has at least one of the following characteristics: 1) M' is Ba 2+ ; 2) A n- Selected from CO3 2- or SO4 2- . Preferably, M and N are Ni 2+ , Fe 3+ , M' is Ba 2+ , A n- For CO3 2- ; and / or, the first transition metal compound comprises a soluble nickel salt, the second transition metal compound comprises a soluble iron salt, and the alkaline earth metal compound comprises a soluble barium salt; Preferably, the nickel salt comprises nickel nitrate, the iron salt comprises iron nitrate, and the alkaline earth metal salt comprises barium nitrate; and / or, the concentrations of the first transition metal compound, the second transition metal compound, and the alkaline earth metal compound contained in the mixed reaction solution are 0.1-1 mmol / L, 0.2-0.5 mmol / L, and 0.1-1 mmol / L, respectively; And / or, the alkaline substance includes any one or more combinations of urea, hexamethylenetetraammonium or triethanolamine.

7. The method for activating a hydrogen electrolysis catalyst according to any one of claims 1 to 2, characterized in that: include: The catalyst is placed in an alkaline solution containing sulfate ions, wherein the pH value of the alkaline solution is 13-14, and an activation treatment is performed by an electrochemical method.

8. The activation method according to claim 7, characterized in that: The electrochemical method includes a combination of one or more of cyclic voltammetry, linear sweep voltammetry and constant current charge-discharge method; preferably, the electrochemical method is cyclic voltammetry, wherein the scanning voltage used is 0V to 1V, the scanning voltage speed is 5mV / s to 50mV / s, the scanning number is 10 to 30 circles, and the scanning environment temperature is room temperature; And / or, the alkaline solution contains sulfate ions at a concentration of 0.01 to 0.1 mol / L, preferably, the alkaline solution contains sulfate, and the sulfate includes sodium sulfate or potassium sulfate; And / or, the alkaline solution contains an alkaline substance with a concentration of 0.1 to 1 mol / L, and the alkaline substance includes sodium hydroxide or potassium hydroxide.

9. An activated electrolytic hydrogen production catalyst, characterized in that: The invention comprises the electrolytic hydrogen production catalyst according to any one of claims 1 to 2 and a sulfate activation layer, wherein the sulfate activation layer comprises sulfate ions distributed on the surface of the catalyst, and the sulfate ions are combined with alkaline earth metal ions in the catalyst.

10. The activated hydrogen electrolysis catalyst according to claim 9, characterized in that: The nano-layer structure is distributed on the surface of the catalyst, wherein the nano-layer structure comprises a plurality of nano-particles, the particle size of the nano-particles is greater than 0 but less than 5 nm, and the nano-particles are formed by combining the sulfate ions with the alkaline earth metal ions in the catalyst.

11. An anode for producing hydrogen by electrolysis, characterized in that: The anode comprises the electrolytic hydrogen production catalyst according to any one of claims 1 to 2 or the activated electrolytic hydrogen production catalyst according to any one of claims 9 to 10; Preferably, a plurality of the catalyst nanosheets are vertically arranged on the surface of the anode and densely arranged to form an array structure; the specific surface area of ​​the array structure is 40 to 50 m2 / g; Preferably, the anode further comprises a conductive substrate for supporting the catalyst, and the conductive substrate comprises foamed nickel, nickel mesh, foamed iron or foamed nickel-iron.

12. Use of the hydrogen production electrolysis catalyst according to any one of claims 1 to 2, the activated hydrogen production electrolysis catalyst according to any one of claims 9 to 10, or the hydrogen production electrolysis anode according to claim 11 in hydrogen production electrolysis; Preferably, the application includes: The electrolytic hydrogen production anode and cathode are placed in an aqueous solution containing chloride ions, and a working voltage is applied between the anode and cathode; particularly preferably, the aqueous solution containing chloride ions includes seawater or chlorine-containing industrial wastewater.

13. Use of the electrolytic hydrogen production catalyst according to any one of claims 1 to 2 in electrolytic hydrogen production, the application comprising: The electrolytic hydrogen production anode and cathode are placed in an aqueous solution containing chloride ions and sulfate ions, and a working voltage is applied between the anode and cathode to achieve electrolytic hydrogen production; the anode includes the electrolytic hydrogen production catalyst.

14. A method for producing hydrogen by electrolysis, characterized in that: include: Placing the anode and cathode for hydrogen production by electrolysis according to claim 11 into an aqueous solution containing chloride ions, and applying a working voltage between the anode and cathode, thereby realizing hydrogen production by electrolysis; Preferably, the aqueous solution containing chloride ions includes seawater or chlorine-containing industrial wastewater.

15. A hydrogen production system by electrolysis, comprising an anode and a cathode, characterized in that: The electrolytic hydrogen production system is used for producing hydrogen by electrolyzing an aqueous solution containing chloride ions, and the anode comprises the electrolytic hydrogen production anode according to claim 11. Preferably, the aqueous solution containing chloride ions includes seawater or chlorine-containing industrial wastewater.

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