Preparation method of CoNiFe-based water electrolysis hydrogen production catalyst

Abstract

The present invention belongs to the field of catalyst preparation technology, specifically to a method for preparing a CoNiFe-based catalyst for hydrogen production by water electrolysis. A CoNiFe-based precursor is first calcined to obtain a metal oxide powder, which is then mixed with carbon black and ball-milled before secondary calcination to obtain the CoNiFe-based catalyst. This catalyst is then loaded onto a carbon paper surface as a working electrode to construct a three-electrode system for water electrolysis, exhibiting dual catalytic performance for both OER and HER.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation, and in particular relates to a method for preparing a CoNiFe-based water electrolysis hydrogen production catalyst. Background Art

[0002] Hydrogen (H2), due to its high energy density and environmentally friendly, recyclable combustion products, has long been considered one of the cleanest and most promising energy carriers, and a promising candidate for future low-carbon energy systems. However, current hydrogen production relies primarily on fossil fuels, resulting in excessive resource consumption and associated greenhouse gas emissions, posing serious environmental challenges. Therefore, the development of clean, renewable alternative energy sources is imperative over the coming decades to gradually replace traditional fossil fuels, drive the transformation of the global energy mix, address current energy and environmental challenges, and ensure sustainable social development.

[0003] Among existing green hydrogen production technologies, water electrolysis is the most mature. This technology produces oxygen and hydrogen through water electrolysis, requiring only pollutant-free water as the raw material. The entire process produces no carbon-containing byproducts, and oxygen, as the sole byproduct, contributes to mitigating the greenhouse effect. The resulting hydrogen can be further converted into electricity and injected into the power grid, providing power for various energy-consuming systems, optimizing the energy mix and improving grid security.

[0004] The process of hydrogen production by water electrolysis involves two key reactions: the oxygen evolution reaction (OER) at the anode and the hydrogen evolution reaction (HER) at the cathode. Due to their slow reaction kinetics, the HER and OER require high overpotentials for proper operation, resulting in low energy conversion efficiency. Therefore, developing efficient and low-cost catalysts to improve reaction efficiency has become a key research direction.

[0005] Although Ru, Ir, and Pt-based materials are currently considered the most effective HER and OER electrocatalysts, these materials are limited by resource scarcity, high cost, and insufficient stability. Future research will focus on identifying alternative catalytic materials that are more economical, stable, and highly active to promote further development in this field. Summary of the Invention

[0006] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0007] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0008] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing a CoNiFe-based water electrolysis hydrogen production catalyst.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0010] The present invention first provides a method for preparing a CoNiFe-based catalyst, comprising the following steps:

[0011] (1) Dissolve Co salt, Ni salt, and Fe salt in water to prepare a metal salt solution; dissolve trimesic acid, triazole, and poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) in N,N-dimethylformamide (DMF) to prepare a dispersion solution; mix the metal salt solution and the dispersion solution evenly, heat and stir in a water bath until a metal organic gel is formed, and filter, wash, dry, and grind to obtain a precursor powder;

[0012] (2) The precursor powder is calcined in an air atmosphere to obtain a metal oxide powder; the metal oxide powder is mixed with carbon black and ball-milled to obtain a mixed powder; the mixed powder is calcined in a N2 atmosphere to obtain a CoNiFe-based catalyst.

[0013] As a preferred embodiment of the present invention, in step (1), the total molar concentration of metal ions in the metal salt solution is 0.6-0.8 mol / L; the molar percentages of Co salt, Ni salt and Fe salt are 40-47.5%:40-47.5%:5-20%; preferably, the molar percentages of Co salt, Ni salt and Fe salt are 45%:45%:10%.

[0014] As a preferred embodiment of the present invention, the Co salt, the Ni salt and the Fe salt are respectively nitrates or nitrate hydrates thereof.

[0015] As a preferred embodiment of the present invention, the molar ratio of trimesic acid to triazole is 1:6; in the dispersed solution, the molar concentration of trimesic acid is 0.15-0.2 mol / L, and the mass concentration of the poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) is 30-40 g / L.

[0016] As a preferred solution of the present invention, the volume ratio of the metal salt solution to the dispersed solution is 3:11.

[0017] As a preferred embodiment of the present invention, the water bath heating in step (1) is performed at a temperature of 90° C. for 4 hours.

[0018] As a preferred embodiment of the present invention, in step (2), the precursor powder is calcined at a temperature of 450° C. in an air atmosphere for a period of 2 h.

[0019] As a preferred embodiment of the present invention, the mass ratio of metal oxide powder to carbon black is 1:0.5-2; preferably 1:1-2, more preferably 1:1.

[0020] As a preferred embodiment of the present invention, the mixed powder is calcined at a temperature of 400-1000°C in a N2 atmosphere for 3 hours; preferably, the calcination temperature is 400-600°C, and more preferably, the calcination temperature is 600°C.

[0021] The present invention further provides a CoNiFe-based catalyst prepared by the above preparation method.

[0022] The present invention also provides an application of the above-mentioned CoNiFe-based catalyst in hydrogen production by water electrolysis. Specifically, the CoNiFe-based catalyst is loaded on the surface of a conductive substrate as a working electrode in a three-electrode system to electrolyze water.

[0023] More specifically, 4 mg of catalyst was weighed, 0.3 mL of ultrapure water, 0.6 mL of isopropanol, and 0.1 mL of NaFion solution were added, and the mixture was ultrasonically mixed for 30 min to prepare a catalyst suspension. The suspension was then dropped onto a 0.5 cm × 0.5 cm carbon paper and allowed to dry to prepare a catalyst suspension with a catalyst loading of 0.48 mg cm -2 working electrode.

[0024] In the three-electrode system, the working electrode is catalyst-loaded carbon paper, the reference electrode is Ag / AgCl electrode, and the counter electrode is platinum mesh; the device uses 1 M KOH as the electrolyte at room temperature and pressure, and performs electrochemical water decomposition through an electrochemical workstation.

[0025] Beneficial effects of the present invention:

[0026] The present invention sinters the precursor in a muffle furnace, allowing for a full reaction at a higher temperature, removing impurities, and improving the purity of the metal oxide. Ball milling the metal oxide and carbon black further uniformizes the particle size, increases the contact area with the carbon black, and enhances its conductivity, thereby improving reaction efficiency and product uniformity during the subsequent tube furnace sintering process. When the precursor, after muffle furnace and ball milling, is sintered in a tube furnace, the reaction is more complete, more efficient, and requires less time and energy.

[0027] The present invention provides a method for preparing a CoNiFe-based catalyst for water electrolysis to produce hydrogen. In this method, Co, Ni, and Fe groups are combined with carbon black in a controllable manner to form a carbon-coated transition metal oxide, which is successfully applied to water decomposition to produce hydrogen, accelerating the reaction rate. At the same time, the catalytic performance of the carbon-coated ternary CoNiFe alloy for water electrolysis to produce hydrogen is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0029] Figure 1 is the HER activity diagram of the catalyst in Examples 1-4 of the present invention,

[0030] Figure 2 The OER activity diagram of the catalyst in Examples 1-4 of the present invention

[0031] Figure 3 These are the XRD patterns of Co, Ni, CoNi and CoNiFe prepared in Examples 1-4 of the present invention.

[0032] Figure 4 HER activity diagram of the catalysts in Example 1 and Examples 5-7 of the present invention.

[0033] Figure 5 Graphs showing the OER activity of the catalysts in Example 1 and Examples 5-7 of the present invention.

[0034] Figure 6 HER activity diagram of the catalyst in Example 1 and Examples 8-9 of the present invention.

[0035] Figure 7 Graph showing the OER activity of the catalysts in Example 1 and Examples 8-9 of the present invention.

[0036] Figure 8 HER activity diagram of the catalyst in Example 1 and Examples 10-11 of the present invention.

[0037] Figure 9 Graphs showing the OER activity of the catalysts in Examples 1 and 10-11 of the present invention.

[0038] Figure 10 HER activity diagram of the catalysts in Example 1 of the present invention and Comparative Examples 1-3.

[0039] Figure 11 Graph showing the OER activity of the catalysts in Example 1 of the present invention and Comparative Examples 1-3. DETAILED DESCRIPTION

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0041] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0042] Evaluation of electrochemical water splitting performance: The test was carried out using an electrochemical workstation (Donghua Analytical Science, DH7000C).

[0043] In the three-electrode system, the working electrode is catalyst-loaded carbon paper, the reference electrode is Ag / AgCl electrode, and the counter electrode is platinum mesh; the device is tested at room temperature and pressure with 1 M KOH as the electrolyte.

[0044] First, 4 mg of catalyst was weighed, and 0.3 mL of ultrapure water, 0.6 mL of isopropanol, and 0.1 mL of NaFion solution were added. The mixture was ultrasonically mixed for 30 min to prepare a catalyst suspension. The suspension was then dropped onto a 0.5 cm × 0.5 cm carbon paper and allowed to dry. The catalyst loading was 0.48 mg cm -2 working electrode.

[0045] Secondly, the HER and OER performances were tested separately within a suitable potential range by the linear sweep method (LSV); then the CV curves were continuously tested at different scan rates.

[0046] Finally, the impedance of the catalyst was measured based on a current density of 50 mA cm-3 over the macroscopic area of ​​the electrode. -2 and 100 mA cm -2 As an indicator for evaluating the catalytic activity of the catalyst. Example 1

[0047] The preparation of a CoNiFe-based water electrolysis hydrogen production catalyst comprises the following steps:

[0048] (1) Preparation of precursor:

[0049] The corresponding metal salts ((Co(NO3)2·6H2O: 2.6195 g, Ni(NO3)2·6H2O: 2.6705 g, Fe(NO3)3·9H2O: 0.8203 g)) were dissolved in water (30 g) to prepare metal salt solutions;

[0050] Trimesic acid (4.2886 g), 1,2,4-triazole (8.3721 g), and poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) (4 g) were dissolved in N,N-dimethylformamide (DMF) (103.84 g) to prepare a dispersion solution.

[0051] The two solutions were mixed and stirred for 30 min to ensure uniform mixing;

[0052] The mixed solution was transferred to a water bath and heated at 90°C with stirring for 4 h. The metal organic gel produced after the reaction was filtered, washed, dried, and then ground (particle size was 0.207 nm) to obtain a precursor powder.

[0053] (2) Calcination of the precursor into carbon-coated transition metal oxides by a two-step process:

[0054] In the first step, 2 g of the precursor was transferred into a muffle furnace, heated to 450 °C at a rate of 5 °C min-1 under air atmosphere, and calcined for 2 h.

[0055] In the second step, the obtained oxide was mixed with carbon black (Sanhua Mall, Keqin Carbon EC600JD) in a mass ratio of 1:1 (i.e., 0.1g:0.1g) and ball milled (frequency: 300*10rpm, time 100s, number of times 24 times). Then, the mixture was moved into a tube furnace and heated at 5℃ min under N2 atmosphere. -1 The temperature is raised to 600° C. at a rate of 0.05° C. and calcined for 3 h to obtain a black solid powder, which is the catalyst for the water electrolysis hydrogen production reaction.

[0056] (3) The above catalyst was prepared into a working electrode for electrochemical water splitting test:

[0057] For HER, the catalyst drove 100 mA cm in 1 M KOH electrolyte. -2 The overpotential for the current density is 365 mV; for OER, the catalyst drives 50 mA cm in 1 M KOH electrolyte. -2 The overpotential of the current density is 372 mV. Example 2

[0058] Preparation of Co-based catalysts for hydrogen production by water electrolysis

[0059] The metal salt solution was prepared by dissolving 5.8212 g of Co(NO3)2·6H2O in 30 g of water. Other operations were the same as in Example 1.

[0060] The Co-based catalyst was prepared as a working electrode for electrochemical water splitting test: for HER, the catalyst drove 100 mA cm in 1 M KOH electrolyte.-2 The overpotential for the current density is 400 mV; for OER, the catalyst drives 50 mA cm in 1 MKOH electrolyte. -2 The overpotential of the current density is 440 mV. Example 3

[0061] Preparation of Ni-based catalysts for hydrogen production by water electrolysis

[0062] The metal salt solution is prepared by dissolving 5.9345 g of Ni(NO3)2·6H2O in 30 g of water; other operations are the same as those in Example 1.

[0063] The Ni-based catalyst was prepared as a working electrode for electrochemical water splitting test: for HER, the catalyst drove 100 mA cm in 1 M KOH electrolyte. -2 The overpotential for the current density is 383 mV; for OER, the catalyst drives 50 mA cm in 1 MKOH electrolyte. -2 The overpotential for the current density is 825 mV. Example 4

[0064] Preparation of CoNi-based catalysts for hydrogen production by water electrolysis

[0065] The metal salt solution is prepared by dissolving Co(NO3)2·6H2O (2.9106 g) and Ni(NO3)2·6H2O (2.9672 g) in water (30 g) to prepare a CoNi salt solution; other operations are the same as in Example 1.

[0066] The CoNi-based catalyst was prepared as a working electrode for electrochemical water splitting test: for HER, the catalyst drove 100 mA cm in 1 M KOH electrolyte. -2 The overpotential for the current density is 419 mV; for OER, the catalyst drives 50 mA cm in 1 MKOH electrolyte. -2 The overpotential of the current density is 470 mV. Example 5

[0067] The difference between this embodiment and embodiment 1 is that the calcination temperature in the second step of step (2) is 400°C.

[0068] The catalyst was prepared as a working electrode for electrochemical water splitting test: for HER, the catalyst drove 100 mA cm in 1 MKOH electrolyte. -2 The overpotential for the current density is 375 mV; for OER, the catalyst drives 50 mA cm in 1 M KOH electrolyte. -2The overpotential of the current density is 402 mV. Example 6

[0069] The difference between this embodiment and embodiment 1 is that the calcination temperature in the second step of step (2) is 800°C.

[0070] The catalyst was prepared as a working electrode for electrochemical water splitting test: for HER, the catalyst drove 100 mA cm in 1 MKOH electrolyte. -2 The overpotential for the current density is 394 mV; for OER, the catalyst drives 50 mA cm in 1 M KOH electrolyte. -2 The overpotential for the current density is 415 mV. Example 7

[0071] The difference between this embodiment and embodiment 1 is that the calcination temperature in the second step of step (2) is 1000°C.

[0072] The catalyst was prepared as a working electrode for electrochemical water splitting test: for HER, the catalyst drove 100 mA cm in 1 MKOH electrolyte. -2 The overpotential for the current density is 370 mV; for OER, the catalyst drives 50 mA cm in 1 M KOH electrolyte. -2 The overpotential of the current density is 471 mV. Example 8

[0073] The difference between this embodiment and embodiment 1 is that in step (1), the metal salt solution is prepared by dissolving the corresponding nitrates (Co(NO3)2·6H2O: 2.7651 g, Ni(NO3)2·6H2O: 2.8189 g, Fe(NO3)3·9H2O: 0.4102 g) in water (30 g). Other operations are the same as those in embodiment 1.

[0074] The catalyst was prepared as a working electrode for electrochemical water splitting test: for HER, the catalyst drove 100 mA cm in 1 MKOH electrolyte. -2 The overpotential for the current density is 423 mV; for OER, the catalyst drives 50 mA cm in 1 M KOH electrolyte. -2 The overpotential of the current density is 420 mV. Example 9

[0075] The difference between this embodiment and embodiment 1 is that in step (1), the metal salt solution is prepared by dissolving the corresponding nitrates (Co(NO3)2·6H2O: 2.3285 g, Ni(NO3)2·6H2O: 2.3738 g, Fe(NO3)3·9H2O: 1.6406 g) in water (30 g). Other operations are the same as those in embodiment 1.

[0076] The catalyst was prepared as a working electrode for electrochemical water splitting test: for HER, the catalyst drove 100 mA cm in 1 MKOH electrolyte. -2 The overpotential for the current density is 402 mV; for OER, the catalyst drives 50 mA cm in 1 M KOH electrolyte. -2 The overpotential of the current density is 392 mV. Example 10

[0077] The difference between this embodiment and embodiment 1 is that in the second step (2), the obtained oxide and carbon black are mixed and ball-milled in a mass ratio of 1:2 (i.e., 0.05 g:0.1 g). The other steps are the same as those in embodiment 1.

[0078] The catalyst was prepared as a working electrode for electrochemical water splitting test: for HER, the catalyst drove 100 mA cm in 1 MKOH electrolyte. -2 The overpotential for the current density is 400 mV; for OER, the catalyst drives 50 mA cm in 1 M KOH electrolyte. -2 The overpotential of the current density is 426 mV. Example 11

[0079] The difference between this embodiment and embodiment 1 is that in the second step (2), the obtained oxide and carbon black are mixed and ball-milled in a mass ratio of 2:1 (i.e., 0.1 g:0.05 g). The other steps are the same as those in embodiment 1.

[0080] The catalyst was prepared as a working electrode for electrochemical water splitting test: for HER, the catalyst drove 100 mA cm in 1 MKOH electrolyte. -2 The overpotential for the current density is 376 mV; for OER, the catalyst drives 50 mA cm in 1 M KOH electrolyte. -2 The overpotential of the current density is 397 mV. Comparative Example 1

[0081] The difference between this comparative example and Example 1 is that the first calcination operation in step (2) is not performed, and 2 g of the precursor powder and carbon black are directly mixed and ball-milled in a mass ratio of 1:1 (i.e., 0.1 g:0.1 g), and the temperature is raised to 600°C at a rate of 5°C min-1 under a N2 atmosphere, and the mixture is kept at this temperature and calcined for 3 h to obtain a catalyst for water electrolysis hydrogen production reaction.

[0082] The catalyst was prepared as a working electrode for electrochemical water splitting test: for HER, the catalyst drove 100 mA cm in 1 MKOH electrolyte. -2 The overpotential for the current density is 395 mV; for OER, the catalyst drives 50 mA cm in 1 M KOH electrolyte. -2 The overpotential of the current density is 396 mV. Comparative Example 2

[0083] The difference between this comparative example and Example 1 is that carbon black is not added in the second step of step (2), and the other operations are the same as those in Example 1.

[0084] The catalyst was prepared as a working electrode for electrochemical water splitting test: for HER, the catalyst drove 100 mA cm in 1 MKOH electrolyte. -2 The overpotential for the current density is 370 mV; for OER, the catalyst drives 50 mA cm in 1 M KOH electrolyte. -2 The overpotential of the current density is 380 mV. Comparative Example 3

[0085] The precursor was prepared according to the method of Example 1, and the precursor was moved into a tube furnace and heated at 5°C min under N2 atmosphere. -1 The temperature was raised to 600 °C at a rate of 1000 °C and kept at this temperature for calcination for 3 h to obtain a catalyst for hydrogen production by water electrolysis.

[0086] The catalyst was prepared as a working electrode for electrochemical water splitting test: for HER, the catalyst drove 100 mA cm in 1 MKOH electrolyte. -2 The overpotential for the current density is 418 mV; for OER, the catalyst drives 50 mA cm in 1 M KOH electrolyte. -2 The overpotential of the current density is 427 mV.

[0087] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, and all of these should be included in the scope of the present invention.

Claims

1. A method for preparing a CoNiFe-based catalyst, characterized in that: The steps include: (1) Dissolving Co salt, Ni salt, and Fe salt in water to prepare a metal salt solution; dissolving trimesic acid, triazole, and poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) in N,N-dimethylformamide to prepare a dispersion solution; uniformly mixing the metal salt solution and the dispersion solution, heating and stirring in a water bath until a metal organic gel is formed, and filtering, washing, drying, and then grinding to obtain a precursor powder; (2) The precursor powder is calcined in an air atmosphere at a calcination temperature of 450°C for 2 hours to obtain a metal oxide powder; the metal oxide powder is mixed with carbon black and ball-milled to obtain a mixed powder; the mixed powder is calcined in a nitrogen atmosphere at a calcination temperature of 400-1000°C for 3 hours to obtain a CoNiFe-based catalyst.

2. The method for preparing a CoNiFe-based catalyst according to claim 1, wherein The total molar concentration of metal ions in the metal salt solution of step (1) is 0.6-0.8 mol / L; the molar percentages of Co salt, Ni salt and Fe salt are 40-47.5%: 40-47.5%: 5-20%.

3. The method for preparing a CoNiFe-based catalyst according to claim 1, wherein The molar concentration of trimesic acid in the dispersed solution of step (1) is 0.15-0.2 mol / L, the mass concentration of poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) is 30-40 g / L, the molar ratio of trimesic acid to triazole is 1:6; and the volume ratio of the metal salt solution to the dispersed solution is 3:

11.

4. The method for preparing a CoNiFe-based catalyst according to claim 1, wherein The water bath heating temperature in step (1) is 90° C. and the heating time is 4 h.

5. The method for preparing a CoNiFe-based catalyst according to claim 1, wherein The mass ratio of the metal oxide powder to the carbon black is 1:0.5-2.

6. A CoNiFe-based catalyst prepared according to the method according to any one of claims 1 to 5.

7. Use of the CoNiFe-based catalyst according to claim 6 in hydrogen production by water electrolysis.

8. The use according to claim 7, characterized in that The CoNiFe-based catalyst is loaded on the surface of a conductive substrate to prepare a working electrode, and a three-electrode system is constructed for water electrolysis.

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