An oxygen evolution catalyst for water electrolysis and its preparation method, and an alkaline water electrolysis hydrogen production device.

Abstract

The present invention relates to a catalyst for oxygen evolution by electrolysis of water, a preparation method thereof, and an alkaline water electrolysis hydrogen production device. The catalyst for oxygen evolution by electrolysis of water is a spherical catalyst containing nickel and iron, and the surface of the spherical catalyst has a porous structure with nanoscale pores, wherein the molar ratio of nickel to iron is 1:(0.1-0.5). The preparation method of the catalyst for oxygen evolution by electrolysis of water comprises: dissolving a nickel precursor and an iron precursor in a solvent, adding a spherical template, a surfactant and a precipitant, then performing a hydrothermal reaction, separating a solid phase product and sintering; the spherical template is a polystyrene microsphere and / or an inorganic carbon microsphere. The catalyst for oxygen evolution by electrolysis of water of the present invention is hollow spherical and has a porous structure on the surface. The catalyst has a large specific surface area and high catalytic activity, and the current density and oxygen evolution performance of the electrolytic cell are significantly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a water electrolysis oxygen evolution catalyst and a preparation method thereof, and an alkaline water electrolysis hydrogen production device. Background Art

[0002] Hydrogen energy is an efficient, clean and environmentally friendly energy source, and is an important support for achieving carbon neutrality. At present, the electrolysis of water is mature and widely used in the current commercial hydrogen production technology. Among them, alkaline water electrolysis is an important technology for large-scale hydrogen production, and it is also one of the most mature hydrogen production technologies. In alkaline water electrolysis, the electrolyzer is its core component, which is composed of multiple unit chambers arranged in a regular pattern. Each chamber is mainly composed of a plate, a diaphragm, a cathode and anode electrodes and a pole frame. Hydrogen and oxygen are produced on the electrode surfaces of the cathode and anode, respectively. Among them, the catalyst plays a core and key role in the efficiency of the electrolyzer and directly affects the current density of the electrolyzer. At present, the cathode catalyst of the alkaline electrolyzer in industry is mainly nickel foam, while the anode either does not use a catalyst or uses a conventional sheet catalyst with low catalytic activity. Therefore, in order to improve the efficiency of hydrogen production by alkaline water electrolysis, it is urgent to develop anode catalysts with high catalytic activity. Summary of the invention

[0003] The present invention provides a water electrolysis oxygen evolution catalyst and a preparation method thereof, and an alkaline water electrolysis hydrogen production device. The water electrolysis oxygen evolution catalyst of the present invention is hollow spherical and has a porous structure on the surface to increase the specific surface area of ​​the catalyst, thereby improving the oxygen evolution performance and hydrogen production efficiency of the electrolyzer.

[0004] In a first aspect, the present invention relates to a water electrolysis oxygen evolution catalyst, which is a spherical catalyst containing nickel and iron, and the surface of the spherical catalyst has a porous structure with nanoscale pores, wherein the molar ratio of nickel to iron is 1:(0.1-0.5).

[0005] Optionally, the water electrolysis oxygen evolution catalyst is in the shape of a hollow sphere with a diameter of 25 to 1200 nm; the water electrolysis oxygen evolution catalyst contains nickel oxide and / or hydroxide and iron oxide and / or hydroxide.

[0006] In a second aspect, the present invention relates to a method for preparing a water electrolysis oxygen evolution catalyst, which is the water electrolysis oxygen evolution catalyst described above, and the preparation method comprises: dissolving a nickel precursor and an iron precursor in a solvent, adding a spherical template, a surfactant and a precipitant, and then performing a hydrothermal reaction, separating a solid phase product and sintering; the spherical template is a polystyrene microsphere and / or an inorganic carbon microsphere.

[0007] Optionally, the nickel precursor is selected from a combination of one or more of nickel nitrate, nickel acetate, nickel sulfate and nickel chloride.

[0008] Optionally, the iron precursor is ferric chloride and / or ferric nitrate.

[0009] Optionally, the solvent is selected from a combination of one or more of water, ethanol, propanol and n-butanol; and the diameter of the spherical template is 25 to 1200 nm.

[0010] Optionally, the precipitant is selected from a combination of one or more of sodium hydroxide, aqueous ammonia, tris(hydroxymethyl)aminomethane, hexamethylenetetramine and triethanolamine.

[0011] Optionally, the surfactant is selected from a nonionic surfactant or an ionic surfactant, the nonionic surfactant is a polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer and / or polyethylene glycol, and the ionic surfactant is hexadecyltrimethylammonium bromide.

[0012] Optionally, the molar ratio of the nickel precursor calculated in nickel, the iron precursor calculated in iron, the spherical template, the surfactant, the precipitant and the solvent is 1: (0.1~0.5): (0.01~0.1): (0.01~0.3): (0.01~0.2): (10~100); when the precipitant is ammonia water, in the molar ratio, the precipitant is calculated in terms of the amount of ammonia.

[0013] Optionally, the temperature of the hydrothermal reaction is 80-160° C. and the time is 4-20 h; the temperature of the sintering is 300-800° C. and the time is 2-10 h.

[0014] In a third aspect, the present invention relates to an alkaline water electrolysis hydrogen production device, which is provided with a cathode and an anode, and the anode is provided with an oxygen evolution catalyst, and the oxygen evolution catalyst is the water electrolysis oxygen evolution catalyst described in the first aspect of the present invention, or is prepared by the preparation method described in the second aspect of the present invention.

[0015] Beneficial effects:

[0016] The water electrolysis oxygen evolution catalyst of the present invention is in the shape of a hollow sphere and has a porous structure on the surface. The catalyst has a large specific surface area and high catalytic activity, and the current density and oxygen evolution performance of the electrolytic cell are significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a SEM photograph of the spherical catalyst prepared in Example 1 of the present invention;

[0018] Figure 2 is a SEM photograph of the spherical catalyst prepared in Example 2 of the present invention;

[0019] Figure 3is a SEM photograph of the surface of the spherical catalyst prepared in Example 2 of the present invention;

[0020] Figure 4 1 is a nitrogen adsorption-desorption curve diagram of the catalyst prepared in Example 1 of the present invention and Comparative Example 1;

[0021] Figure 5 It is a linear cyclic voltammetry curve diagram of the catalyst prepared in Example 1 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0022] The present application is further described in detail below through the accompanying drawings and embodiments. Through these descriptions, the characteristics and advantages of the present application will become clearer and more specific.

[0023] The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise noted.

[0024] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0025] In a first aspect, the present invention relates to a water electrolysis oxygen evolution catalyst, which is a spherical catalyst containing nickel and iron, and the surface of the spherical catalyst has a porous structure with nanoscale pores, wherein the molar ratio of nickel to iron is 1:(0.1-0.5).

[0026] It should be noted that if Figure 1 It can be seen that the electrolytic water oxygen evolution catalyst of the present invention is spherical. Figure 3 It can be seen that the surface of the water electrolysis oxygen evolution catalyst is composed of many catalyst particles, there are holes between adjacent catalyst particles, there are many holes between many catalyst particles, and the holes formed by many catalyst particles together constitute the porous structure. In short, a porous structure is formed between the particles accumulated on the surface. The water electrolysis oxygen evolution catalyst of the present invention is spherical, and the porous structure is formed on the surface. The water electrolysis oxygen evolution catalyst has a large specific surface area, can provide more catalytic active sites for the oxygen evolution reaction of the anode, and can improve the current density of hydrogen production by alkaline water electrolysis.

[0027] According to an embodiment of the first aspect of the present invention, the electrolytic water oxygen evolution catalyst is a hollow sphere with a diameter of 25 to 1200 nm; the electrolytic water oxygen evolution catalyst contains nickel oxide and / or hydroxide and iron oxide and / or hydroxide.

[0028] It should be noted that the oxidation of water in the process of water electrolysis is a very critical and extremely complex reaction, which determines the energy consumption and efficiency of water electrolysis. The electrolysis oxygen evolution catalyst of the present invention is composed of nickel oxide and / or hydroxide and iron oxide and / or hydroxide phases, and is composed of Figure 2 It can be seen that the catalyst has a hollow spherical morphology, which makes the water electrolysis oxygen evolution catalyst have a higher specific surface area and catalytic activity, and can significantly improve the oxygen evolution performance of the electrolyzer, thereby improving the overall hydrogen production efficiency of alkaline water electrolysis.

[0029] In a second aspect, the present invention relates to a method for preparing the catalyst for oxygen evolution by electrolysis of water of the first aspect, the preparation method comprising: dissolving a nickel precursor and an iron precursor in a solvent, adding a spherical template, a surfactant and a precipitant, and then performing a hydrothermal reaction, separating a solid phase product and sintering; the spherical template is a polystyrene microsphere and / or an inorganic carbon microsphere.

[0030] It should be noted that in the preparation method of the present invention, the nickel precursor and the iron precursor are dissolved in a solvent so that nickel and iron exist in the solution in the form of ions. The spherical template, surfactant and precipitant can be added to the solution containing nickel and iron ions at the same time and dispersed evenly. Nickel and iron react with the precipitant and form catalyst seeds or crystals on the surface of the spherical template. The presence of the surfactant enables the spherical template to maintain good dispersibility. Then, through a hydrothermal reaction, the catalyst seeds or crystals gradually grow and form a spherical electrolytic water oxygen evolution catalyst. The spherical template is then detached through sintering or roasting to finally form a hollow spherical nickel-iron anode oxygen evolution catalyst.

[0031] It should be noted that the hydrothermal reaction can be carried out in a hydrothermal reaction kettle, and after the solid phase product is separated, it can be dried and then sintered.

[0032] According to an embodiment of the second aspect of the present invention, the nickel precursor is selected from a combination of one or more of nickel nitrate, nickel acetate, nickel sulfate and nickel chloride.

[0033] According to an embodiment of the second aspect of the present invention, the iron precursor is ferric chloride and / or ferric nitrate.

[0034] It should be noted that the water electrolysis oxygen evolution catalyst prepared by the method of the present invention using the nickel precursor and the iron precursor as the raw materials of nickel and iron has good catalytic activity for oxygen evolution at the anode.

[0035] According to an embodiment of the second aspect of the present invention, the solvent is selected from a combination of one or more of water, ethanol, propanol and n-butanol; and the diameter of the spherical template is 25 to 1200 nm.

[0036] It should be noted that the above-mentioned solvent can dissolve the nickel precursor and the iron precursor well, and disperse the spherical template and the surfactant well in the system, so that the nickel ions and the iron ions can react well with the precipitant and crystallize on the surface of the spherical template and react to form a hollow spherical catalyst.

[0037] According to an embodiment of the second aspect of the present invention, the precipitant is selected from a combination of one or more of sodium hydroxide, ammonia water, tris(hydroxymethyl)aminomethane, hexamethylenetetramine and triethanolamine.

[0038] It should be noted that one or a combination of the above substances as a precipitant can react well with nickel ions and iron ions and form hydroxides on the surface of the spherical template, and then after a subsequent sintering step, nickel hydroxide and iron hydroxide can be fully or partially converted into oxides. When the precipitant is sodium hydroxide, the sodium hydroxide can be added to the reaction system in the form of an aqueous solution or a solid form.

[0039] According to one embodiment of the second aspect of the present invention, the surfactant is selected from a non-ionic surfactant or an ionic surfactant, the non-ionic surfactant is a polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer and / or polyethylene glycol, and the ionic surfactant is hexadecyltrimethylammonium bromide.

[0040] As a preferred embodiment, the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer is selected from one or more combinations of P123, F127 and L64.

[0041] It should be noted that the selection of the above-mentioned surfactant can make the spherical template agent well dispersed in the system, so that the electrolytic water oxygen evolution catalyst generated by nickel ions, iron ions and precipitant has better dispersibility, so that the catalyst obtains a larger specific surface area.

[0042] According to an embodiment of the second aspect of the present invention, the molar ratio of the nickel precursor calculated in nickel, the iron precursor calculated in iron, the spherical template, the surfactant, the precipitant and the solvent is 1: (0.1-0.5): (0.01-0.1): (0.01-0.3): (0.01-0.2): (10-100); when the precipitant is ammonia water, in the molar ratio, the precipitant is calculated in terms of the amount of ammonia.

[0043] It should be noted that in the preparation method of the water electrolysis oxygen evolution catalyst of the present invention, by selecting the nickel precursor, iron precursor, spherical template, surfactant and precipitant, and controlling the quantitative relationship between the above-mentioned components according to the above-mentioned molar ratio, nickel, iron and precipitant can be further reacted better to obtain a hollow spherical water electrolysis oxygen evolution catalyst with higher oxygen evolution catalytic activity.

[0044] According to an implementation manner of the second aspect of the present invention, the temperature of the hydrothermal reaction is 80-160° C. and the time is 4-20 hours; the temperature of the sintering is 300-800° C. and the time is 2-10 hours.

[0045] It should be noted that carrying out the hydrothermal reaction at the above temperature and time, and carrying out the sintering at the above temperature and time, can make the prepared hollow spherical water electrolysis oxygen evolution catalyst have a more uniform morphology, better dispersibility and a larger specific surface area.

[0046] In a third aspect, the present invention relates to an alkaline water electrolysis hydrogen production device, which is provided with a cathode and an anode, and the anode is provided with an oxygen evolution catalyst, and the oxygen evolution catalyst is the water electrolysis oxygen evolution catalyst described in the first aspect of the present invention, or is prepared by the preparation method described in the second aspect of the present invention.

[0047] It should be noted that in the alkaline water electrolysis hydrogen production device of the present invention, the oxygen evolution catalyst arranged or filled in the anode is a hollow spherical catalyst prepared by the preparation method of the present invention, and the oxygen evolution performance of the electrolyzer is significantly improved, and the hydrogen production efficiency of the electrolyzer is significantly improved.

[0048] The present invention is further illustrated by the following examples, but the present invention is not limited thereto.

[0049] The reagents used in the following examples are all commercially available finished reagents. The polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymers P123, F127 and L64 used in the following examples were purchased from Sigma, and the polystyrene microspheres were purchased from Zhongke Leiming (Beijing) Technology Co., Ltd.

[0050] Example 1

[0051] Catalyst preparation: Precursors Ni(NO3)2·4H2O, FeCl3 and water as solvent were mixed to obtain an aqueous solution, surfactant P123, polystyrene microspheres with a diameter of 100 nm, and 30% by mass ammonia water were added to the aqueous solution and stirred to mix evenly, the molar ratio of nickel, iron, water as solvent, P123, polystyrene microspheres with a diameter of 100 nm, and ammonia was 1:0.5:30:0.015:0.012:0.1, and then reacted at 120°C for 10 hours. The precipitate was filtered, separated, dried, placed in a muffle furnace, and calcined at 400°C for 4 hours to obtain a spherical porous nickel-iron catalyst.

[0052] Example 2

[0053] Catalyst preparation: Precursors NiCl2·4H2O, FeCl3·4H2O and water as solvent were mixed to obtain an aqueous solution, surfactant F127, polystyrene microspheres with a diameter of 50 nm and sodium hydroxide were added to the aqueous solution and stirred and mixed evenly, the molar ratio of nickel, iron, water as solvent, F127, polystyrene microspheres with a diameter of 50 nm and sodium hydroxide was 1:0.4:50:0.01:0.01:0.01, and then reacted at 120°C for 10 hours. The precipitate was filtered, separated, dried and placed in a muffle furnace, and calcined at 450°C for 5 hours to obtain a spherical porous nickel-iron catalyst.

[0054] Example 3

[0055] Catalyst preparation: Precursors NiCl2·4H2O, FeCl3·4H2O and water as solvent were mixed to obtain an aqueous solution, surfactant P123, polystyrene microspheres with a diameter of 25 nm and sodium hydroxide were added to the aqueous solution and stirred to mix evenly, the molar ratio of nickel, iron, water as solvent, P123, polystyrene microspheres with a diameter of 25 nm and sodium hydroxide was 1:0.3:50:0.01:0.015:0.01, and then reacted at 140°C for 12 hours. The precipitate was filtered, separated, dried and placed in a muffle furnace, and calcined at 350°C for 5 hours to obtain a spherical porous nickel-iron catalyst.

[0056] Example 4

[0057] Catalyst preparation: Precursors NiCl2·4H2O, FeCl3·4H2O and water as solvent are mixed to obtain an aqueous solution, surfactant P123, polystyrene microspheres with a diameter of 250nm, and 30% by mass ammonia solution are added to the aqueous solution and stirred and mixed evenly, the molar ratio of nickel, iron, water as solvent, P123, polystyrene microspheres with a diameter of 250nm, and ammonia is 1:0.2:50:0.01:0.017:0.01, and then reacted at 160℃ for 8h. The precipitate is filtered, separated, dried, placed in a muffle furnace, and calcined at 500℃ for 5h to obtain a spherical porous nickel-iron catalyst.

[0058] Comparative Example 1

[0059] The catalyst was prepared according to the method of Example 1, except that:

[0060] During the preparation process, surfactant P123 and polystyrene microspheres were not added to obtain a powdered nickel-iron catalyst.

[0061] Comparative Example 2

[0062] The catalyst was prepared according to the method of Example 2, except that:

[0063] During the preparation process, surfactant F127 and polystyrene microspheres were not added to obtain a powdered nickel-iron catalyst.

[0064] Test Example 1

[0065] The catalysts prepared in Examples 1 and 2 were analyzed by scanning electron microscope. The SEM photo of the catalyst prepared in Example 1 is shown in FIG. Figure 1 The SEM photo of the catalyst prepared in Example 2 is shown in Figure 2 and Figure 3 .

[0066] pass Figure 1 It can be seen that the catalyst prepared in Example 1 is spherical. Figure 2 It can be seen that the catalyst prepared in Example 2 is spherical and hollow. Figure 3 It can be seen that the surface of the catalyst prepared in Example 2 has a porous structure. The surface of the catalyst is composed of many particles arranged regularly, and a porous structure of stacked nano-scale pores is formed between adjacent particles.

[0067] Test Example 2

[0068] The specific surface areas of the catalysts prepared in the above examples and comparative examples were tested by the BET method. The values ​​of the measured specific surface areas are shown in Table 1 below, where the nitrogen adsorption and desorption curves of Example 1 and Comparative Example 1 are shown in Table 1. Figure 4 As shown, Figure 4In the nitrogen adsorption-desorption curve, the horizontal axis is the relative pressure and the vertical axis is the adsorption volume.

[0069] Table 1

[0070] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 <![CDATA[Specific surface area m 2 / g]]> 199.45 186.52 179.62 183.21 18.56 16.45

[0071] It can be seen from the data in Table 1 that the hollow spherical catalyst prepared by the method of the present invention in the above examples has a porous structure on the surface, and the specific surface area of ​​the catalyst is significantly increased. Figure 4 It can be seen from the nitrogen adsorption-desorption curve that the spherical material prepared in Example 1 has a mesoporous structure.

[0072] Test Example 3

[0073] The catalysts prepared in the above examples and comparative examples were used as anode oxygen evolution catalysts to test the performance of hydrogen production by electrolysis. 3 The alkaline electrolytic cell hydrogen production device, the alkali solution is a 30wt% KOH aqueous solution, and the current density is tested under a single cell 2V voltage operation. The tested values ​​are shown in the following Table 2:

[0074] Table 2

[0075] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 <![CDATA[Current density A / m 2 > 5600 5500 5400 5500 4500 4300

[0076] It can be seen from the data in Table 2 that the use of the catalyst prepared in the above embodiment as an anode oxygen evolution catalyst can significantly increase the current density when producing hydrogen by alkaline electrolysis.

[0077] Test Example 4

[0078] The oxygen evolution performance of the spherical catalyst prepared in Example 1 and the powdered catalyst prepared in Comparative Example 1 was analyzed using an electrochemical workstation rotating disk electrode. The obtained linear cyclic voltammetry curves are shown in FIG. Figure 5 As shown, Figure 5 The vertical axis is the oxygen evolution current density, and the horizontal axis is the potential. Figure 5 It can be seen that the spherical catalyst prepared in Example 1 exhibits a higher oxygen evolution current density, indicating that the spherical catalyst exhibits better oxygen evolution performance due to its higher specific surface area.

[0079] In the description of the present application, it should be noted that the terms "upper", "lower", "inside", "outside", "front", "back", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships in the working state of the present application. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on the present application.

[0080] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "install", "connect" and "connect" should be understood in a broad sense. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0081] The present application has been described above in conjunction with preferred embodiments, but these embodiments are only exemplary and serve only as an illustration. On this basis, various replacements and improvements may be made to the present application, all of which fall within the scope of protection of the present application.

Claims

1. A catalyst for oxygen evolution by water electrolysis, characterized in that The electrolytic water oxygen evolution catalyst is a spherical catalyst containing nickel and iron, and the surface of the spherical catalyst has a porous structure with nano-scale pores, wherein the molar ratio of nickel to iron is 1:(0.1-0.5); The preparation method of the water electrolysis oxygen evolution catalyst comprises: A nickel precursor and an iron precursor are dissolved in a solvent, a spherical template, a surfactant and a precipitant are added, and then a hydrothermal reaction is carried out, and a solid phase product is separated and sintered; The nickel precursor is selected from a combination of one or more of nickel nitrate, nickel acetate, nickel sulfate and nickel chloride; the iron precursor is ferric chloride and / or ferric nitrate; the spherical template is polystyrene microspheres and / or inorganic carbon microspheres; The surfactant is selected from a nonionic surfactant or an ionic surfactant, the nonionic surfactant is a polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer and / or polyethylene glycol, and the ionic surfactant is hexadecyltrimethylammonium bromide; the precipitant is selected from a combination of one or more of sodium hydroxide, ammonia water, trishydroxymethylaminomethane, hexamethylenetetramine and triethanolamine; The molar ratio of the nickel precursor calculated in nickel, the iron precursor calculated in iron, the spherical template, the surfactant, the precipitant and the solvent is 1: (0.1-0.5): (0.01-0.1): (0.01-0.3): (0.01-0.2): (10-100); when the precipitant is ammonia water, in the molar ratio, the precipitant is calculated in terms of the amount of ammonia; The temperature of the hydrothermal reaction is 80-160° C. and the time is 4-20 hours; the temperature of the sintering is 300-800° C. and the time is 2-10 hours.

2. The water electrolysis oxygen evolution catalyst according to claim 1, characterized in that The electrolytic water oxygen evolution catalyst is in the shape of a hollow sphere with a diameter of 25 to 1200 nm; The water electrolysis oxygen evolution catalyst comprises nickel oxide and / or hydroxide and iron oxide and / or hydroxide.

3. The water electrolysis oxygen evolution catalyst according to claim 1, characterized in that The solvent is selected from a combination of one or more of water, ethanol, propanol and n-butanol; The diameter of the spherical template is 25 to 1200 nm.

4. An alkaline water electrolysis hydrogen production device, the alkaline water electrolysis hydrogen production device is provided with a cathode and an anode, the anode is provided with an oxygen evolution catalyst, characterized in that: The oxygen evolution catalyst is the water electrolysis oxygen evolution catalyst according to any one of claims 1 to 3.

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