Anode catalyst, preparation method therefor, and application thereof

Abstract

An anode catalyst, a preparation method therefor, and an application thereof. The anode catalyst comprises a catalytic layer and a protective layer covering the surface of the catalytic layer; the material of the catalytic layer includes an iron-cobalt-nickel oxide, and the material of the protective layer includes a metal oxide Lewis acid.

Description

Anode catalyst and its preparation method and application

[0001] Related applications

[0002] This application claims priority to Chinese patent application number 202311010892.9, filed on August 11, 2023, entitled “Anode Catalyst, Preparation Method and Application Thereof,” the entire text of which is hereby incorporated by reference. Technical Field

[0003] The present application relates to the field of electrochemical catalysis technology, and in particular to an anode catalyst and a preparation method and application thereof. Background Art

[0004] Hydrogen energy is an efficient, clean and environmentally friendly energy source, and is an important support for achieving carbon neutrality. It is estimated that by 2060, my country's annual demand for hydrogen will reach 130 million tons, and about 1.17 billion tons of pure water will be consumed for electrolysis each year. The shortage of fresh water resources will seriously restrict the development of green hydrogen technology. The development of seawater hydrogen production is an important direction for the future development of hydrogen energy.

[0005] Due to the complex composition of seawater, direct hydrogen production from seawater electrolysis presents significant challenges. For example, seawater contains a large amount of chloride ions, which can cause severe corrosion of anode materials, leading to electrode damage and excessive voltage. To slow chloride ion corrosion on anode materials, traditional methods primarily involve adding alkaline solutions to increase the selectivity of the oxygen evolution reaction and improve anode efficiency. However, this approach increases the cost of seawater electrolysis.

[0006] Summary of the Invention

[0007] In a first aspect, the present application provides an anode catalyst, comprising a catalytic layer and a protective layer covering the surface of the catalytic layer;

[0008] The material of the catalytic layer includes iron, cobalt and nickel oxide;

[0009] The material of the protective layer includes a metal oxide Lewis acid.

[0010] In some embodiments, the protective layer has a porous structure.

[0011] In some embodiments, the porosity of the protective layer is 40% to 60%.

[0012] In some embodiments, the metal oxide Lewis acid is selected from one or more of manganese oxide, chromium oxide, titanium oxide, cerium oxide, molybdenum oxide, and zirconium oxide.

[0013] In some embodiments, the metal oxide Lewis acid is selected from one or more of manganese dioxide, chromium trioxide, titanium dioxide, cerium oxide, molybdenum trioxide and zirconium oxide.

[0014] In some embodiments, the chemical formula of the iron-cobalt-nickel oxide is Fe x Co y Ni z O means that x, y and z satisfy:

[0015] x+y+z=1, x is 0.1~0.5, y is 0.1~0.5, and z is 0.1~0.7.

[0016] In some embodiments, the iron-cobalt-nickel oxide has a one-dimensional linear structure, a two-dimensional layered structure, or a three-dimensional porous structure.

[0017] In some embodiments, the particle size of the material of the catalytic layer is 5 nm to 1000 nm.

[0018] In some embodiments, the particle size of the material of the protective layer is 5 nm to 1000 nm.

[0019] In some embodiments, the protective layer has a thickness of 0.5 μm to 10 μm.

[0020] In a second aspect, the present application provides a method for preparing the anode catalyst as described above, comprising:

[0021] The metal oxide Lewis acid is coated on the surface of the iron-cobalt-nickel oxide.

[0022] In some embodiments, the step of coating the surface of the iron-cobalt-nickel oxide with a metal oxide-based Lewis acid comprises the following steps:

[0023] (a) dissolving a metal oxide Lewis acid precursor in a solvent to obtain a precursor solution;

[0024] (b) applying the precursor solution on the surface of the iron-cobalt-nickel oxide, and

[0025] (c) calcining the iron-cobalt-nickel oxide produced in step (b).

[0026] In some embodiments, the precursor solution further comprises a pore-forming agent. In one embodiment, the pore-forming agent is added to the precursor solution in step (a).

[0027] In some embodiments, the pore-forming agent is selected from one or more of triblock copolymer P123, triblock copolymer F127, triblock copolymer L64, polyethylene glycol, and hexadecyltrimethylammonium bromide.

[0028] In some embodiments, the molar ratio of the precursor to the pore-forming agent is 1:(0.01-0.3).

[0029] In some embodiments, the calcination conditions include: a calcination temperature of 350° C. to 600° C., a heating rate of 0.5° C. / min to 5° C. / min, and a calcination time of 2 h to 8 h.

[0030] In some embodiments, the solvent is selected from one or more of water, ethanol, n-butanol, isopropanol, and N,N-dimethylformamide.

[0031] In some embodiments, the molar ratio of the precursor to the solvent is 1:(5-100).

[0032] In some embodiments, the precursor is selected from one or more of manganese nitrate, manganese chloride, chromium nitrate, zirconium oxychloride, titanium tetrachloride, cerium nitrate, molybdenum nitrate, tetrabutyl titanate, and tetraethyl titanate.

[0033] In some embodiments, after step (b) and before step (c), the method further comprises a step (d): drying the iron-cobalt-nickel oxide in step (b) at a temperature of 40° C. to 100° C. and a relative humidity of 20% to 80% for 2 h to 10 h.

[0034] In a third aspect, the present application provides a method for producing hydrogen from seawater, comprising:

[0035] Pre-treating seawater to obtain seawater electrolyte; and

[0036] The anode catalyst described in the first aspect or the anode catalyst prepared by the method described in the second aspect is used to catalyze the hydrogen production reaction of the seawater electrolyte.

[0037] In some embodiments, pre-treating the seawater comprises:

[0038] mixing seawater with alkali and sodium carbonate to form a precipitate, and collecting the supernatant; and

[0039] The supernatant is microfiltered to obtain the seawater electrolyte.

[0040] In some embodiments, the base is selected from sodium hydroxide or potassium hydroxide.

[0041] This application has at least the following beneficial effects:

[0042] The anode catalyst provided herein comprises an iron-cobalt-nickel oxide catalytic layer and a metal oxide Lewis acid protective layer covering the surface. The catalytic layer catalyzes the hydrogen production reaction from seawater, while the protective layer generates hydroxide ions on the catalyst surface, creating a localized alkaline environment that prevents chloride ions from entering the catalytic layer, improving the chlorine resistance and selectivity of the catalytic layer for the oxygen evolution reaction, thereby ensuring the long-term, efficient, and stable operation of the anode catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the disclosed drawings without any creative work.

[0044] FIG1 is a process flow chart of hydrogen production by seawater electrolysis according to an embodiment of the present application.

[0045] FIG2 is a linear sweep voltammetry curve of the anode catalyst with different protective layers in seawater of the present application. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0047] Unless otherwise defined herein, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are intended solely for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0048] Where “including,” “having,” and “comprising” are used herein, it is intended to cover a non-exclusive inclusion, and another component may also be added unless a clear limiting term such as “only,” “consisting of,” etc. is used.

[0049] In the present application, “further”, “further”, “particularly”, etc. are used for descriptive purposes to indicate differences in content, but should not be understood as limiting the scope of protection of the present application.

[0050] In this application, "at least one" means more than one, such as one, two, or more than two. "Multiple" or "several" means at least two, such as two or three, etc., unless otherwise specifically defined. "Multi-layer" means at least two layers, such as two or three, etc., unless otherwise specifically defined. In the description of this application, "several" means at least one, such as one or two, etc., unless otherwise specifically defined.

[0051] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein are understood to include any and all subranges subsumed therein.

[0052] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0053] Unless mentioned otherwise, terms in the singular may include plural forms and should not be construed as having one number.

[0054] In this application, “above” or “below” includes the number itself. For example, “1 below” includes 1.

[0055] In this application, A@B, B is the covering layer or surface layer, and substance A is the covered layer or catalytic layer. The double-layer structure A@B means that B covers A.

[0056] The present application provides an anode catalyst, its preparation method, and application. The anode catalyst has a double-layer structure, including a catalytic layer and a protective layer covering the surface of the catalytic layer. The protective layer can prevent chloride ions from entering the catalytic layer, improve the chlorine resistance of the catalytic layer, and ensure the long-term efficient and stable operation of the catalyst. When used in the process of catalyzing hydrogen production from seawater, the anode catalyst can alleviate the severe corrosion of the electrode material by chloride ions in seawater and improve the catalyst's selectivity for the oxygen evolution reaction.

[0057] In some embodiments, the present application provides an anode catalyst. The anode catalyst includes a catalytic layer and a protective layer covering the surface of the catalytic layer;

[0058] The material of the catalytic layer includes iron, cobalt and nickel oxide;

[0059] The material of the protective layer includes a metal oxide Lewis acid.

[0060] The anode catalyst has a double-layer structure, including an iron-cobalt-nickel oxide core and a metal oxide Lewis acid shell covering its surface. Among them, the catalytic layer (inner layer, or catalyst) has the function of catalyzing the hydrogen production reaction from seawater, and the protective layer (covering layer) can generate hydroxide ions on the surface of the catalytic layer, forming a local alkaline environment, thereby preventing chloride ions from entering the catalytic layer, improving the chlorine resistance stability of the catalytic layer, and playing a role in protecting the catalyst. At the same time, it can also improve the selectivity of the catalytic layer for the oxygen evolution reaction, thereby ensuring the long-term efficient and stable operation of the anode catalyst.

[0061] In some embodiments, the chemical formula of the iron-cobalt-nickel oxide is Fe x Co y Ni z O means that x, y and z satisfy:

[0062] x+y+z=1, where x is 0.1-0.5, y is 0.1-0.5, and z is 0.1-0.7. Such an iron-cobalt-nickel oxide has a higher selectivity for catalyzing the oxygen evolution reaction. It is understood that x includes, but is not limited to, 0.1, 0.2, 0.3, 0.4, or 0.5; y includes, but is not limited to, 0.1, 0.2, 0.3, 0.4, or 0.5; and z includes, but is not limited to, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, or 0.7.

[0063] In some embodiments, the iron-cobalt-nickel oxide has a one-dimensional linear structure, a two-dimensional layered structure, or a three-dimensional porous structure. Such an iron-cobalt-nickel oxide has a large specific surface area and can deliver excellent catalytic performance.

[0064] In some embodiments, the particle size of the material of the catalytic layer is 5 nm to 1000 nm. Catalysts in this particle size range are easy to prepare and have excellent catalytic effects. It is understood that the particle size of the catalyst includes, but is not limited to, 5 nm, 10 nm, 50 nm, 100 nm, 200 nm, 300 nm, 350 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, or 1000 nm.

[0065] In some embodiments, the protective layer has a porous structure, which is beneficial for water molecules to better enter the surface of the catalytic layer (such as nickel-iron-cobalt catalyst) to perform oxygen evolution reaction.

[0066] In some embodiments, the porosity of the protective layer is 40% to 60%. Such a porous protective layer is more conducive to water molecules better entering the surface of the catalytic layer (such as nickel-iron-cobalt catalyst) to carry out oxygen evolution reaction. It is understood that the porosity of the protective layer includes but is not limited to 40%, 42%, 45%, 46%, 48%, 50%, 51%, 52%, 53%, 55%, 56%, 58% or 60%.

[0067] In some embodiments, the metal oxide Lewis acid is selected from one or more of manganese oxide, chromium oxide, titanium oxide, cerium oxide, molybdenum oxide and zirconium oxide. These metal oxide Lewis acids can better generate hydroxide ions on the surface of the catalytic layer, forming a local alkaline environment, thereby preventing chloride ions from entering the catalytic layer and improving the chlorine resistance stability of the catalyst.

[0068] In some embodiments, the metal oxide Lewis acid is selected from one or more of manganese dioxide, chromium trioxide, titanium dioxide, cerium oxide, molybdenum trioxide, and zirconium oxide. These metal oxide Lewis acids can better generate hydroxide ions on the surface of the catalyst layer, forming a local alkaline environment, thereby preventing chloride ions from entering the catalyst layer and improving the chlorine resistance stability of the catalyst.

[0069] In some embodiments, the thickness of the protective layer is 0.5 μm to 10 μm. The appropriate thickness can prevent chloride ions from entering the catalytic layer while not affecting the entry of hydroxide ions into the catalytic layer for oxygen evolution reaction. It is understandable that the thickness of the protective layer includes but is not limited to 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm. In one embodiment, the thickness of the protective layer is 1 μm to 10 μm. In another embodiment, the thickness of the protective layer is 1 μm to 8 μm.

[0070] In some embodiments, the particle size of the protective layer material is 5 nm to 1000 nm. Selecting a protective layer material with an appropriate particle size is beneficial to the transfer of hydroxide ions in the protective layer. It is understood that the particle size of the protective layer material includes but is not limited to 5 nm, 10 nm, 50 nm, 100 nm, 200 nm, 300 nm, 350 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, or 1000 nm.

[0071] In some embodiments, the present application further provides a method for preparing the anode catalyst as described above, comprising:

[0072] The metal oxide Lewis acid is coated on the surface of the iron-cobalt-nickel oxide.

[0073] In some embodiments, the step of coating the surface of the iron-cobalt-nickel oxide with a metal oxide-based Lewis acid comprises the following steps:

[0074] (a) dissolving a metal oxide Lewis acid precursor in a solvent to obtain a precursor solution;

[0075] (b) applying the precursor solution on the surface of the iron-cobalt-nickel oxide, and

[0076] (c) calcining the iron-cobalt-nickel oxide in step (b).

[0077] In some embodiments, the precursor solution further comprises a pore-forming agent. In one embodiment, the pore-forming agent is added to the precursor solution in step (a).

[0078] In some embodiments, the pore-forming agent is selected from one or more of triblock copolymer P123, triblock copolymer F127, triblock copolymer L64, polyethylene glycol, and hexadecyltrimethylammonium bromide.

[0079] In some embodiments, the molar ratio of the precursor to the pore-forming agent is 1:(0.01-0.3), including but not limited to 1:0.01, 1:0.02, 1:0.05, 1:0.08, 1:0.1, 1:0.12, 1:0.15, 1:0.18, 1:0.2, 1:0.22, 1:0.25, 1:0.28 or 1:0.3.

[0080] In some embodiments, the calcination temperature is 350°C to 600°C. The anode catalyst calcined in this temperature range is suitable for water electrolysis. It is understood that the calcination temperature includes but is not limited to 350°C, 400°C, 450°C, 500°C, 550°C or 600°C.

[0081] In some embodiments, the calcination time is 2 hours to 8 hours. Adequate calcination time ensures stable performance of the anode catalyst. It is understood that the calcination time includes but is not limited to 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours or 8 hours.

[0082] Furthermore, the heating rate during the calcination process is 0.5°C / min to 5°C / min. A suitable heating rate can avoid affecting the material microstructure and ensure the particle size of the protective layer material, thereby ensuring catalytic performance. It is understood that the heating rate includes but is not limited to 0.5°C / min, 1°C / min, 1.5°C / min, 2°C / min, 2.5°C / min, 3°C / min, 3.5°C / min, 4°C / min, 4.5°C / min, or 5°C / min.

[0083] In some embodiments, the solvent is selected from one or more of water, ethanol, n-butanol, isopropanol, and N,N-dimethylformamide.

[0084] In some embodiments, the molar ratio of the precursor to the solvent is 1:(5-100), including but not limited to 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, 1:60, 1:65, 1:70, 1:75, 1:80, 1:85, 1:90 or 1:100.

[0085] In some embodiments, the precursor is selected from one or more of manganese nitrate, manganese chloride, chromium nitrate, zirconium oxychloride, titanium tetrachloride, cerium nitrate, molybdenum nitrate, tetrabutyl titanate, and tetraethyl titanate.

[0086] In some embodiments, after step (b) of applying the precursor solution to the surface of the iron-cobalt-nickel oxide and before step (c) of calcining, the method further includes step (d) of drying the iron-cobalt-nickel oxide in step (b) at a temperature of 40°C to 100°C and a relative humidity of 20% to 80% for 2 hours to 10 hours.

[0087] In some embodiments, the method for preparing the anode catalyst comprises the following steps:

[0088] S1: dissolving a metal oxide Lewis acid precursor in a solvent, adding a pore-forming agent, and stirring uniformly to prepare a precursor solution;

[0089] S2: coating the precursor solution on the surface of the iron-cobalt-nickel oxide; in some embodiments, the method is performed by spin coating or dipping;

[0090] S3: The iron-cobalt-nickel oxide coated with the precursor solution is placed in an oven for drying, and then placed in a muffle furnace for calcination to obtain an anode catalyst material.

[0091] The present application also provides the application of the anode catalyst as described above, and the technical solution is as follows.

[0092] A method for producing hydrogen from seawater is provided, comprising the following steps:

[0093] Pre-treating seawater to prepare seawater electrolyte;

[0094] The anode catalyst as described above or the anode catalyst prepared by the method as described above is used to catalyze the hydrogen production reaction of seawater electrolyte.

[0095] In some embodiments, the pre-treating of seawater comprises the following steps:

[0096] Mix seawater with alkali and sodium carbonate to remove calcium and magnesium ions from the seawater, and collect the supernatant after sedimentation;

[0097] The supernatant is subjected to microfiltration treatment to remove microorganisms and suspended matter in the seawater and prepare seawater electrolyte.

[0098] In some embodiments, the base is selected from sodium hydroxide or potassium hydroxide.

[0099] FIG1 shows a process flow chart of hydrogen production by electrolysis of seawater according to an embodiment of the present application.

[0100] The present application is further described in detail below with reference to specific examples.

[0101] Example 1

[0102] This embodiment provides an anode catalyst material, a preparation method thereof, and an application thereof, as detailed below.

[0103] (1) Preparation of anode catalyst materials:

[0104] Tetrabutyl titanate was dissolved in n-butanol, and triblock copolymer F127, a pore-forming agent, was added and stirred to obtain a precursor solution, i.e., a coating solution for the protective layer. The molar ratio of the precursor, solvent, and pore-forming agent was 1:50:0.01. The precursor solution was then coated on the iron-cobalt-nickel oxide (Fe 0.2 Co 0.3 Ni 0.5 O) surface. The iron-cobalt-nickel oxide coated with the precursor solution was dried at 60°C and 40% relative humidity for 10 hours and then calcined in a muffle furnace at a heating rate of 2°C / min, a calcination temperature of 400°C, and a calcination time of 4 hours to obtain an anode catalyst (iron-cobalt-nickel@titanium dioxide) with a protective layer. The protective layer is a titanium dioxide material. The porosity of the protective layer was 47.8% after nitrogen adsorption and desorption testing using the BET (Brunauer-Emmett-Teller) method. Scanning electron microscopy showed that the particle size of the protective layer material was approximately 60 nm. In addition, the thickness of the protective layer was approximately 2 μm.

[0105] (2) Hydrogen production from seawater:

[0106] Seawater pretreatment: KOH and sodium carbonate are added to the seawater to completely precipitate the calcium and magnesium ions in the seawater, and then the seawater enters the ultrafiltration and microfiltration devices to remove suspended matter and microorganisms in the seawater.

[0107] The prepared iron-cobalt-nickel@titanium dioxide material was placed in an electrolytic cell as an anode catalyst, and pretreated seawater was used as the electrolyte. The test showed that the hydrogen production reaction could run stably for 2000 hours, with an average voltage of 1.8V in the electrolytic cell and a current density of 4000A / m 2 .

[0108] Example 2

[0109] This embodiment provides an anode catalyst material and its preparation method and application, as follows:

[0110] (1) Preparation of anode catalyst materials:

[0111] Chromium nitrate was dissolved in n-butanol, and the pore-forming agent triblock copolymer P123 was added and stirred evenly to obtain a precursor solution, i.e., the coating solution of the protective layer. The molar ratio of the precursor, solvent and pore-forming agent was 1:60:0.015. The precursor solution was then coated on the iron-cobalt-nickel oxide (Fe 0.2 Co 0.3 Ni 0.5 O) surface. The iron, cobalt, nickel oxide coated with the precursor solution was dried at 80°C and 20% relative humidity for 10 hours, and then placed in a muffle furnace for calcination at a heating rate of 1°C / min, a calcination temperature of 400°C, and a calcination time of 4 hours to obtain an anode catalyst (iron, cobalt, nickel @ chromium trioxide) with a protective layer. The protective layer is a chromium trioxide material. Using the BET (Brunauer-Emmett-Teller) method, the porosity of the protective layer was 51.2% after nitrogen adsorption and desorption testing. Using a scanning electron microscope, the particle size of the protective layer material was approximately 80nm. In addition, the thickness of the protective layer was approximately 1μm.

[0112] (2) Hydrogen production from seawater:

[0113] Seawater pretreatment: KOH and sodium carbonate are added to the seawater to completely precipitate the calcium and magnesium ions in the seawater, and then the seawater enters the ultrafiltration and microfiltration devices to remove suspended matter and microorganisms in the seawater.

[0114] The prepared iron-cobalt-nickel@chromium oxide material was placed in an electrolytic cell as an anode catalyst, and pretreated seawater was used as the electrolyte. The test showed that the hydrogen production reaction could run stably for 2000 hours, with an average voltage of 1.85V in the electrolytic cell and a current density of 4500A / m 2 .

[0115] Example 3

[0116] This embodiment provides an anode catalyst material and its preparation method and application, as follows:

[0117] (1) Preparation of anode catalyst materials:

[0118] Manganese nitrate was dissolved in ethanol and the pore-forming agent triblock copolymer F127 was added and stirred evenly to obtain a precursor solution, i.e., the coating solution for the protective layer. The molar ratio of the precursor, solvent, and pore-forming agent was 1:70:0.02. The precursor solution was then coated on the iron-cobalt-nickel oxide (Fe) by spin coating. 0.4 Co 0.1 Ni 0.5 O) surface. The iron, cobalt, nickel oxide coated with the precursor solution was dried at 60°C and 20% relative humidity for 10 hours, and then placed in a muffle furnace for calcination at a heating rate of 5°C / min, a calcination temperature of 500°C, and a calcination time of 3 hours to obtain an anode catalyst (iron, cobalt, nickel @ manganese dioxide) with a protective layer. The protective layer is a manganese dioxide material. Using the BET (Brunauer-Emmett-Teller) method, the porosity of the protective layer was 42.8% after nitrogen adsorption and desorption testing. The particle size of the protective layer was approximately 100nm when photographed using a scanning electron microscope. In addition, the thickness of the protective layer was approximately 5μm.

[0119] (2) Hydrogen production from seawater:

[0120] Seawater pretreatment: KOH and sodium carbonate are added to the seawater to completely precipitate the calcium and magnesium ions in the seawater, and then the seawater enters the ultrafiltration and microfiltration devices to remove suspended matter and microorganisms in the seawater.

[0121] The prepared iron-cobalt-nickel@manganese dioxide material was placed in an electrolytic cell as an anode catalyst, and pretreated seawater was used as the electrolyte. The test showed that the hydrogen production reaction could run stably for 2000 hours, with an average voltage of 1.75V in the electrolytic cell and a current density of 4200A / m 2 .

[0122] Example 4

[0123] This embodiment provides an anode catalyst material and its preparation method and application, as follows:

[0124] (1) Preparation of anode catalyst materials

[0125] Dissolve zirconium oxychloride in water, add the pore-forming agent triblock copolymer L64 and stir evenly to obtain a precursor solution, i.e., the coating solution for the protective layer. The molar ratio of the precursor, solvent and pore-forming agent is 1:100:0.03. Then, the precursor solution is coated on the iron-cobalt-nickel oxide (Fe 0.1 Co0.2 Ni 0.7 O) surface. The iron, cobalt, nickel oxide coated with the precursor solution was dried at 100°C and 20% relative humidity for 3 hours, and then placed in a muffle furnace for calcination at a heating rate of 1°C / min, a calcination temperature of 600°C, and a calcination time of 2 hours to obtain an anode catalyst (iron, cobalt, nickel @ zirconium oxide) with a protective layer. The protective layer is a zirconium oxide material. The porosity of the protective layer was tested by nitrogen adsorption and desorption using the BET (Brunauer-Emmett-Teller) method and was found to be 42.8%. The particle size of the protective layer material was approximately 1000nm using a scanning electron microscope. In addition, the thickness of the protective layer was approximately 8μm.

[0126] (2) Hydrogen production from seawater:

[0127] Seawater pretreatment: KOH and sodium carbonate are added to the seawater to completely precipitate the calcium and magnesium ions in the seawater, and then the seawater enters the ultrafiltration and microfiltration devices to remove suspended matter and microorganisms in the seawater.

[0128] The prepared iron-cobalt-nickel@zirconia material was placed in an electrolytic cell as an anode catalyst, and pretreated seawater was used as the electrolyte. The test showed that the hydrogen production reaction could run stably for 2000 hours, with an average voltage of 1.75V in the electrolytic cell and a current density of 3800A / m 2 .

[0129] Example 5

[0130] This embodiment provides an anode catalyst material and its preparation method and application, as follows:

[0131] (1) Preparation of anode catalyst materials

[0132] Dissolve molybdenum nitrate in water, add the pore-forming agent triblock copolymer P123 and stir evenly to obtain a precursor solution, i.e., the coating solution of the protective layer. The molar ratio of the precursor, solvent and pore-forming agent is 1:60:0.07. Then, the precursor solution is coated on the iron-cobalt-nickel oxide (Fe 0.1 Co 0.2 Ni 0.7 O) surface. The iron, cobalt, nickel oxide coated with the precursor solution was dried at 80°C and 60% relative humidity for 4 hours, and then placed in a muffle furnace for calcination at a heating rate of 2°C / min, a calcination temperature of 550°C, and a calcination time of 2 hours to obtain an anode catalyst (iron, cobalt, nickel @ molybdenum trioxide) with a protective layer. The protective layer is a molybdenum trioxide material. Using the BET (Brunauer-Emmett-Teller) method, the porosity of the protective layer was 51.1% after nitrogen adsorption and desorption testing. The particle size of the protective layer material was approximately 180nm using a scanning electron microscope. In addition, the thickness of the protective layer was approximately 5μm.

[0133] (2) Hydrogen production from seawater:

[0134] Seawater pretreatment: KOH and sodium carbonate are added to the seawater to completely precipitate the calcium and magnesium ions in the seawater, and then the seawater enters the ultrafiltration and microfiltration devices to remove suspended matter and microorganisms in the seawater.

[0135] The prepared iron-cobalt-nickel@molybdenum trioxide material was placed in an electrolytic cell as an anode catalyst, and pretreated seawater was used as the electrolyte. The test showed that the hydrogen production reaction could run stably for 2000 hours, with an average voltage of 1.75V in the electrolysis chamber and a current density of 3800A / m 2 .

[0136] Example 6

[0137] This embodiment provides an anode catalyst material and its preparation method and application, as follows:

[0138] (1) Preparation of anode catalyst materials

[0139] Dissolve cerium nitrate in water, add pore-forming agent triblock copolymer P123 and stir evenly to obtain a precursor solution, i.e., the coating solution of the protective layer. The molar ratio of precursor, solvent and pore-forming agent is 1:50:0.05. Then, the precursor solution is coated on the iron-cobalt-nickel oxide (Fe 0.1 Co 0.2 Ni 0.7 O) surface. The iron, cobalt, nickel oxide coated with the precursor solution was dried at 80°C and 40% relative humidity for 5 hours, and then placed in a muffle furnace for calcination at a heating rate of 3°C / min, a calcination temperature of 600°C, and a calcination time of 2 hours to obtain an anode catalyst (iron, cobalt, nickel @ cerium oxide) with a protective layer. The protective layer is a cerium oxide material. Using the BET (Brunauer-Emmett-Teller) method, the porosity of the protective layer was 45.2% after nitrogen adsorption and desorption testing. Scanning electron microscopy was used to photograph the protective layer material, and the particle size of the protective layer material was approximately 200nm. In addition, the thickness of the protective layer was approximately 6μm.

[0140] (2) Hydrogen production from seawater:

[0141] Seawater pretreatment: KOH and sodium carbonate are added to the seawater to completely precipitate the calcium and magnesium ions in the seawater, and then the seawater enters the ultrafiltration and microfiltration devices to remove suspended matter and microorganisms in the seawater.

[0142] The prepared iron-cobalt-nickel@cerium oxide material was used as the anode catalyst in the electrolytic cell, and pretreated seawater was used as the electrolyte. The test showed that the hydrogen production reaction could run stably for 2000 hours, with an average voltage of 1.75V in the electrolytic cell and a current density of 3800A / m 2 .

[0143] Example 7

[0144] This embodiment uses iron-cobalt-nickel@titanium dioxide-0.5 as the anode catalyst, wherein the thickness of the titanium dioxide layer is 0.5 μm. The difference between the anode catalyst material of this embodiment and that of embodiment 1 is only the thickness of the titanium dioxide layer.

[0145] Seawater pretreatment: KOH and sodium carbonate are added to the seawater to completely precipitate the calcium and magnesium ions in the seawater, and then the seawater enters the ultrafiltration and microfiltration devices to remove suspended matter and microorganisms in the seawater.

[0146] The iron-cobalt-nickel@titanium dioxide-0.5 material was placed in the electrolytic cell as the anode catalyst, and pre-treated seawater was used as the electrolyte. The test showed that the hydrogen production reaction could run stably for 2000 hours, with the electrolytic cell voltage of 1.8V and the current density from 4000A / m 2 Reduced to 3600A / m 2 This may be due to the thin thickness of the protective layer, which has an insignificant protective effect on the catalytic layer.

[0147] Example 8

[0148] This embodiment uses iron-cobalt-nickel@titanium dioxide-10 as the anode catalyst, wherein the thickness of the titanium dioxide layer is 10 μm. The difference between the anode catalyst material of this embodiment and that of embodiment 1 is only the thickness of the titanium dioxide layer.

[0149] Seawater pretreatment: KOH and sodium carbonate are added to the seawater to completely precipitate the calcium and magnesium ions in the seawater, and then the seawater enters the ultrafiltration and microfiltration devices to remove suspended matter and microorganisms in the seawater.

[0150] The iron-cobalt-nickel@titanium dioxide-10 material was placed in the electrolytic cell as the anode catalyst, and pre-treated seawater was used as the electrolyte. The test showed that the hydrogen production reaction could run stably for 2000 hours, with an average voltage of 1.8V in the electrolysis chamber and a current density of 3800A / m 2 This may be due to the fact that the conductivity of the electrode decreases slightly with the increase of the protective layer thickness.

[0151] Comparative Example 1

[0152] Compared with Example 1, no metal oxide Lewis acid is used to cover the iron-cobalt-nickel oxide, and the iron-cobalt-nickel oxide is directly used as the anode catalyst for the seawater hydrogen production reaction.

[0153] Seawater pretreatment: KOH and sodium carbonate are added to the seawater to completely precipitate the calcium and magnesium ions in the seawater, and then the seawater enters the ultrafiltration and microfiltration devices to remove suspended matter and microorganisms in the seawater.

[0154] Iron, cobalt and nickel oxides were placed in the electrolytic cell as anode catalysts, and pre-treated seawater was used as the electrolyte. The test showed that the hydrogen production reaction could run stably for 2000 hours, with the electrolytic cell voltage at 1.8V and the current density at 4000A / m 2 Reduced to 2800A / m 2 .

[0155] Comparative Example 2

[0156] Compared with Example 1, iron, cobalt, nickel and magnesium oxide are used as the anode catalyst, and the thickness of the magnesium oxide layer is 4 μm.

[0157] Seawater pretreatment: KOH and sodium carbonate are added to the seawater to completely precipitate the calcium and magnesium ions in the seawater, and then the seawater enters the ultrafiltration and microfiltration devices to remove suspended matter and microorganisms in the seawater.

[0158] Iron, cobalt, nickel and magnesium oxide are placed in the electrolytic cell as anode catalysts, and pre-treated seawater is used as the electrolyte. According to the test, the hydrogen production reaction can run stably for 2000 hours, with an average voltage of 1.8V in the electrolytic cell and a current density of 4000A / m 2 Reduced to 2600A / m 2 .

[0159] Figure 2 is a linear sweep voltammetry curve under different catalysts in seawater of Examples 1 to 5 of the present application and Comparative Example 1. The horizontal axis Potential vs. SCE represents the potential relative to the standard calomel electrode (SCE). The vertical axis I represents the current density. As shown in Figure 2, the curve of the iron cobalt nickel oxide (FeCoNi) without adding a protective layer shows an obvious chlorine evolution peak. By adding a protective layer, the chlorine evolution reaction is suppressed to a certain extent. The chlorine evolution peak of the curve of the iron cobalt nickel oxide to which titanium dioxide (TiO2 / FeCoNi), chromium trioxide (Cr2O3 / FeCoNi), manganese dioxide (MnO2 / FeCoNi), zirconium oxide (ZrO2 / FeCoNi), or molybdenum trioxide (MoO3 / FeCoNi) is added is significantly weakened, and the effect is obvious. The experimental results show that by coating metal oxide Lewis acids on iron cobalt nickel oxide, the chlorine evolution reaction in the hydrogen production reaction can be suppressed, thereby improving the selectivity of the catalyst for the oxygen evolution reaction.

[0160] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0161] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. An anode catalyst, characterized in that: The anode catalyst comprises a catalytic layer and a protective layer covering the surface of the catalytic layer; The material of the catalytic layer includes iron-cobalt-nickel oxide; The material of the protective layer includes a metal oxide-based Lewis acid.

2. The anode catalyst according to claim 1, characterized in that Satisfy at least one of the following (1) to (2): (1) the protective layer has a porous structure; and (2) The porosity of the protective layer is 40% to 60%.

3. The anode catalyst according to claim 1 or 2, characterized in that: The metal oxide Lewis acid is selected from one or more of manganese oxide, chromium oxide, titanium oxide, cerium oxide, molybdenum oxide and zirconium oxide.

4. The anode catalyst according to any one of claims 1 to 3, characterized in that The metal oxide Lewis acid is selected from one or more of manganese dioxide, chromium trioxide, titanium dioxide, cerium oxide, molybdenum trioxide and zirconium oxide.

5. The anode catalyst according to any one of claims 1 to 4, characterized in that: Satisfy at least one of the following (3) to (4): (3) The chemical formula of the iron-cobalt-nickel oxide is Fe x Co y Ni z O means that x, y and z satisfy: x+y+z=1, x is 0.1-0.5, y is 0.1-0.5, z is 0.1-0.7; and (4) The iron-cobalt-nickel oxide has a one-dimensional linear structure, a two-dimensional layered structure or a three-dimensional porous structure.

6. The anode catalyst according to any one of claims 1 to 5, characterized in that: Satisfy at least one of the following (5) to (7): (5) The particle size of the material of the catalytic layer is 5nm to 1000nm; (6) The particle size of the material of the protective layer is 5 nm to 1000 nm; and (7) The thickness of the protective layer is 0.5 μm to 10 μm.

7. A method for preparing the anode catalyst according to any one of claims 1 to 6, comprising: The metal oxide Lewis acid is coated on the surface of the iron-cobalt-nickel oxide.

8. The method according to claim 7, characterized in that The method of covering the surface of the iron-cobalt-nickel oxide with a metal oxide Lewis acid comprises the following steps: (a) dissolving the metal oxide Lewis acid precursor in a solvent to obtain a precursor solution; (b) applying the precursor solution on the surface of the iron-cobalt-nickel oxide, and (c) calcining the iron-cobalt-nickel oxide in step (b).

9. The method according to claim 8, characterized in that Satisfy at least one of the following (8) to (9): (8) adding a pore-forming agent to the precursor solution; The pore-forming agent is selected from one or more of triblock copolymer P123, triblock copolymer F127, triblock copolymer L64, polyethylene glycol and hexadecyltrimethylammonium bromide; and (9) The molar ratio of the precursor to the pore-forming agent is 1:(0.01-0.3).

10. The method according to claim 8 or 9, characterized in that: Satisfy at least one of the following (10) to (13): (10) The calcination conditions include: a temperature of 350°C to 600°C, a heating rate of 0.5°C / min to 5°C / min, and a calcination time of 2h to 8h; (11) The solvent is selected from one or more of water, ethanol, n-butanol, isopropanol and N,N-dimethylformamide; (12) The molar ratio of the precursor to the solvent is 1:(5-100); and (13) The precursor is selected from one or more of manganese nitrate, manganese chloride, chromium nitrate, zirconium oxychloride, titanium tetrachloride, cerium nitrate, molybdenum nitrate, tetrabutyl titanate and tetraethyl titanate.

11. The method for preparing an anode catalyst according to any one of claims 8 to 10, characterized in that: After step (b) and before step (c), the method further comprises step (d): drying the iron-cobalt-nickel oxide in step (b) at a temperature of 40° C. to 100° C. and a relative humidity of 20% to 80% for 2 h to 10 h.

12. A method for producing hydrogen from seawater, comprising: Pre-treating seawater to obtain seawater electrolyte; as well as The anode catalyst described in any one of claims 1 to 6 or the anode catalyst prepared by the method described in any one of claims 7 to 11 is used to catalyze the hydrogen production reaction of seawater electrolyte.

13. The method according to claim 12, characterized in that The pretreatment of seawater comprises: mixing seawater with alkali and sodium carbonate to form a precipitate, and collecting the supernatant; and The supernatant is microfiltered to obtain the seawater electrolyte.

14. The method according to claim 13, characterized in that The base is selected from sodium hydroxide or potassium hydroxide.

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