Iron-doped ferrocobalt phosphate difunctional electrocatalyst and preparation method thereof

Abstract

The invention discloses an iron-doped ferrocobalt phosphate difunctional electrocatalyst and a preparation method thereof, belongs to the technical field of electrocatalyst preparation, and aims to solve the technical problem that the stability, conductivity and durability of the ferrocobalt phosphate difunctional electrocatalyst in the prior art need to be further improved. The graphene foam nickel-based electrocatalyst comprises the following components in parts by weight: 80-100 parts of a graphene foam nickel substrate and 44-69 parts of a precursor solution, and is prepared by modifying an electrocatalyst through pure foam nickel with positive charges, graphene oxide dispersion liquid with negative charges and a microwave-assisted hydrothermal method. The initial potential of hydrogen evolution reaction and oxygen evolution reaction is reduced, the current density is increased, and the service life is prolonged.

Description

Technical Field

[0001] This invention relates to the field of bifunctional electrocatalyst technology, specifically to an iron-doped cobalt iron phosphate bifunctional electrocatalyst and its preparation method. Background Technology

[0002] With the increasing global energy demand and the growing severity of environmental problems, the development and utilization of clean energy has become a hot research topic. Among them, hydrogen energy, as an ideal clean energy source, has received widespread attention due to its high energy density, environmental friendliness, and renewability. The production of hydrogen mainly relies on the hydrogen evolution reaction and the oxygen evolution reaction. However, existing commercial catalysts are expensive and susceptible to corrosion, which limits their application in large-scale water electrolysis. Therefore, the development of electrocatalysts with low energy consumption, high efficiency, and high stability has become the focus of research.

[0003] In existing technologies, metal-doped phosphate bifunctional electrocatalysts are typically prepared by electrodeposition. However, the low conductivity of phosphate materials limits electron transport efficiency, increases the overpotential of hydrogen evolution reaction and oxygen evolution reaction, and reduces catalytic efficiency. Furthermore, due to the relatively stable structure of phosphates, fewer active sites are exposed, reducing the specific surface area of ​​the electrocatalyst and resulting in a slower reaction rate and lower catalytic efficiency. Although phosphate materials exhibit good chemical stability under certain reaction conditions, they may dissolve, corrode, or degrade under high current density and long-term operation, affecting their stability. Summary of the Invention

[0004] The purpose of this invention is to provide an iron-doped cobalt iron phosphate bifunctional electrocatalyst and its preparation method, in order to solve the technical problems of high energy consumption, low catalytic efficiency and poor stability of existing bifunctional electrocatalysts.

[0005] The objective of this invention can be achieved through the following technical solution: a method for preparing an iron-doped cobalt iron phosphate bifunctional electrocatalyst, comprising the following components by weight: 80-100 parts of graphene foam nickel substrate and 44-69 parts of precursor solution.

[0006] The precursor solution comprises the following components by weight: 20-30 parts cobalt salt, 15-20 parts iron salt, 5-10 parts sodium hypophosphite, 2-5 parts ammonium chloride, and 2-4 parts ammonia.

[0007] Furthermore, the graphene foam nickel substrate is obtained by the following steps:

[0008] A1. Immerse the nickel foam in hydrochloric acid solution and ultrasonically clean it at 25-35℃ for 10 minutes. Rinse it with deionized water until neutral. Then immerse the nickel foam in CTAB aqueous solution and ultrasonically clean it for 10 minutes. Transfer the nickel foam to anhydrous ethanol solution and ultrasonically clean it for 5 minutes. Rinse it with deionized water and vacuum dry it to obtain pure nickel foam with a positive charge.

[0009] The synthesis reaction mechanism of positively charged pure nickel foam:

[0010] Nickel foam is ultrasonically cleaned in hydrochloric acid solution to remove the surface oxide layer and organic contaminants through acid etching, exposing a fresh nickel metal surface and forming a micro-rough structure. It is then immersed in CTAB aqueous solution, where the cationic surfactant CTAB is adsorbed onto the nickel surface through hydrophobic chains, and the quaternary ammonium salt groups form a stable positive charge layer, giving the nickel foam a strong positive charge. Alternating cleaning with anhydrous ethanol and deionized water effectively removes residual impurities and ensures a uniform distribution of surface charge. Finally, a clean and positively charged nickel foam substrate is obtained by vacuum drying.

[0011] A2. Add graphene oxide to deionized water, sonicate for 60 min, add NaOH solution to adjust pH to 9-10, add SDS dispersant, sonicate for 30 min, centrifuge to obtain negatively charged graphene oxide dispersion.

[0012] Synthesis mechanism of negatively charged graphene oxide dispersion:

[0013] Graphene oxide is subjected to high-intensity ultrasonic exfoliation in deionized water, which disrupts the van der Waals forces and hydrogen bonds between the sheets, achieving monolayer dispersion. The pH is adjusted to 9-10 by adding NaOH solution, which causes the carboxylic acid groups at the edges of the graphene oxide to deprotonate into negatively charged carboxylate ions, significantly increasing the surface negative charge density. After adding the anionic dispersant SDS, its sulfonic acid groups are further adsorbed onto the surface of the graphene oxide sheets, inhibiting agglomeration through electrostatic repulsion and steric hindrance. Finally, centrifugation removes the unexfoliated coarse particles, resulting in a uniformly dispersed and negatively charged colloidal solution of graphene oxide.

[0014] A3. The positively charged pure nickel foam is vertically immersed in the negatively charged graphene oxide dispersion. After standing at 25°C for 30 min, it is ultrasonically treated for 10 min. The nickel foam is then removed, rinsed with deionized water, and dried in a vacuum drying oven at 60°C for 2 h to obtain the graphene nickel foam substrate material.

[0015] The synthesis mechanism of graphene foam nickel substrate material is as follows:

[0016] Positively charged nickel foam is vertically immersed in a negatively charged graphene oxide dispersion. The two are driven by electrostatic attraction, which drives the graphene oxide to be directionally adsorbed onto the surface of the nickel foam. During the static stage, a preliminary film is formed. Subsequently, the micro-jet and cavitation effect generated by low-frequency ultrasound promotes the graphene oxide sheets to penetrate into the pores of the nickel foam and breaks the weak interlayer forces to form a dense coating. Finally, the loose adsorbed fragments are removed by rinsing with deionized water. Vacuum drying at 60°C allows the graphene oxide to form a stable bond with the nickel substrate through hydrogen bond recombination and capillary force contraction, resulting in a graphene-based nickel foam material with both high specific surface area and conductivity.

[0017] Furthermore, the preparation method of the precursor solution is as follows: First, cobalt salt and iron salt are added to deionized water and magnetically stirred for 10 minutes until completely dissolved. Then, ammonium chloride and sodium hypophosphite are added and stirred for another 5 minutes. Ammonia water is added dropwise until the pH stabilizes at 9-10, and stirring is continued for 40 minutes to obtain the precursor solution.

[0018] Furthermore, in step A1, the size of the nickel foam is 2cm×4cm, and the volume ratio of hydrochloric acid solution, CTAB aqueous solution and anhydrous ethanol is 5:3:5. The concentration of the hydrochloric acid solution is 3wt%, and the concentration of the CTAB aqueous solution is 0.5wt%.

[0019] Furthermore, in step A2, the ratio of graphene oxide, deionized water, and SDS dispersant is 1g:500mL:0.25g, the concentration of SDS dispersant is 0.05wt%, and the concentration of NaOH solution is 0.4wt%.

[0020] Furthermore, in step A3, the ratio of positively charged pure nickel foam to negatively charged graphene oxide dispersion is 1 g: 50 mL.

[0021] Furthermore, the cobalt salt and iron salt are cobalt nitrate hexahydrate and ferric nitrate nonahydrate, respectively, and the concentration of the ammonia water is 25 wt%.

[0022] A method for preparing an iron-doped cobalt iron phosphate bifunctional electrocatalyst includes the following steps:

[0023] The graphene foam nickel substrate was vertically and completely immersed in the precursor solution and transferred to a 100 mL polytetrafluoroethylene-lined high-pressure reactor. After sealing, it was placed in a microwave reaction chamber, and the temperature of the reaction chamber was rapidly increased to 120 °C. After microwave treatment for 5 min, the temperature was further increased to 140-160 °C and maintained for 30 min. After cooling and cleaning, iron-doped cobalt iron phosphate bifunctional electrocatalyst was obtained.

[0024] The present invention has the following beneficial effects:

[0025] 1. This invention utilizes CTAB aqueous solution to impart a positive charge to the surface of nickel foam. The presence of this positive charge improves the adsorption of reactants, enhances the hydrophilicity of the nickel foam, and increases its specific surface area, providing more active sites for the reaction. This helps improve the efficiency of reactions such as water splitting and enhances the surface stability of the catalyst, preventing corrosion and degradation, thereby further optimizing catalytic performance. SDS dispersant can adsorb onto the surface of graphene oxide, forming a negatively charged protective film. This effectively improves the dispersibility of graphene oxide, preventing its sheet aggregation and agglomeration, ensuring the uniformity and long-term stability of the dispersion. Simultaneously, the negatively charged graphene oxide surface exhibits better hydrophilicity and chemical reactivity, enhancing its activity in electrocatalysis and other reactions, and possesses good electrical conductivity.

[0026] 2. The positively charged nickel foam of the present invention attracts negatively charged graphene oxide through electrostatic interaction. This electrostatic adsorption enhances the dispersion and adhesion of graphene oxide on the surface of the nickel foam, thereby improving the uniform distribution and binding force of graphene on the nickel foam and reducing the risk of sheet detachment. The high porosity of the nickel foam and the high surface area of ​​the graphene enable the active components of the catalyst to be uniformly dispersed and expose more active sites, which significantly improves the catalytic performance of the catalyst, especially showing excellent electrocatalytic activity in the hydrogen evolution and oxygen evolution reactions.

[0027] 3. This invention also utilizes a microwave hydrothermal method to uniformly dope iron ions, improving the electronic structure of the catalyst and enabling it to perform electrocatalytic reactions more efficiently. Microwave heating makes the reaction rapid and efficient, shortening the preparation time and reducing energy consumption. The synthesized catalyst not only has good electrocatalytic performance but also exhibits excellent stability and durability, maintaining high catalytic efficiency during long-term use. Iron doping significantly reduces the overpotential of hydrogen evolution and oxygen evolution reactions by regulating the electronic structure of cobalt, and the heterogeneous interface accelerates charge transport. The three-dimensional porous structure and continuous conductive network of the graphene foam nickel substrate enhance the density of active sites and electronic conduction efficiency. Combined with the microwave rapid synthesis process, kilogram-scale uniform preparation is achieved. Combined with the structural stability of the substrate, it possesses both high efficiency and durability. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a scanning electron microscope image of the iron-doped cobalt iron phosphate bifunctional electrocatalyst prepared in Example 3 of the present invention.

[0030] Figure 2 The constant current stability test curve of the iron-doped cobalt iron phosphate bifunctional electrocatalyst prepared in Example 3 of the present invention for hydrogen evolution by water electrolysis in alkaline electrolyte.

[0031] Figure 3 The constant current stability test curve of the iron-doped cobalt iron phosphate bifunctional electrocatalyst prepared in Example 3 of the present invention for oxygen evolution by water electrolysis in an alkaline electrolyte. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] In this application, the nickel foam is selected from Suzhou Maozhen New Material Technology Co., Ltd., with a nickel content of 99%, a thickness of 10 mm, and a pore size of 0.2-0.6 mm;

[0034] In this application, CTAB is selected from Jining Sanshi Biotechnology Co., Ltd., with CAS number 57-09-0, active ingredient content of 99%, EINECS number 200-311-3, and model number SH-410415;

[0035] In this application, the graphene oxide is selected from Hubei Xinyuhong Biomedical Technology Co., Ltd., with CAS number 1034343-98-0, active ingredient content of 99%, and product number xyh001;

[0036] In this application, the SDS dispersant is selected from Xinsheng (Hubei) Chemical Co., Ltd., with CAS number 151-21-3 and model number SDS.

[0037] In this application, cobalt nitrate hexahydrate is selected from Wuhan Kanos Technology Co., Ltd., CAS No. 10026-22-9, and the content of active ingredient is 99%;

[0038] In this application, ferric nitrate nonahydrate is selected from Jingzhou Yinjie Chemical Co., Ltd., CAS No. 7782-61-8, and the content of active ingredient is 99%;

[0039] Example 1

[0040] This embodiment provides a method for preparing an iron-doped cobalt iron phosphate bifunctional electrocatalyst, comprising the following steps:

[0041] S1. Preparation of positively charged pure nickel foam

[0042] Cutting: 2cm×4cm nickel foam was immersed in 50mL hydrochloric acid solution and ultrasonically cleaned at 25℃ for 10min. After rinsing with deionized water until neutral, the nickel foam was immersed in 30mL CTAB aqueous solution and ultrasonically cleaned for 10min. The nickel foam was then transferred to 50mL anhydrous ethanol solution and ultrasonically cleaned for 5min. After rinsing with deionized water, it was vacuum dried to obtain positively charged pure nickel foam.

[0043] S2. Preparation of negatively charged graphene oxide dispersion

[0044] Weigh 1g of graphene oxide and add it to 500mL of deionized water. Sonicate for 60min, add NaOH solution to adjust the pH to 9, add 0.25g of SDS dispersant, sonicate for 30min, and centrifuge to obtain a negatively charged graphene oxide dispersion.

[0045] S3, Preparation of graphene foam nickel substrate

[0046] Weighing: Vertically immerse the positively charged pure nickel foam into 50 mL of negatively charged graphene oxide dispersion, let it stand at 25 °C for 30 min, then sonicate for 10 min, remove the nickel foam, rinse with deionized water, and dry in a vacuum drying oven at 60 °C for 2 h to obtain the graphene nickel foam substrate material.

[0047] S4. Preparation of precursor solution

[0048] Weigh out 20 parts by weight of cobalt nitrate hexahydrate and 15 parts by weight of ferric nitrate nonahydrate and add them to 40 mL of deionized water. Stir magnetically for 10 min until completely dissolved. Then add 5 parts of sodium hypophosphite and 2 parts of ammonium chloride. Continue stirring for 5 min and then add ammonia dropwise until the pH stabilizes at 9. Continue stirring for 40 min to obtain the precursor solution.

[0049] S5. Preparation of iron-doped cobalt iron phosphate bifunctional electrocatalysts

[0050] Weigh out 80 parts by weight of graphene foam nickel substrate and vertically and completely immerse it in 44 parts of precursor solution. Transfer it to a 100 mL high-pressure reactor lined with polytetrafluoroethylene, seal it and place it in a microwave reaction chamber. Rapidly raise the temperature of the reaction chamber to 120°C and microwave it for 5 min. Then continue to raise the temperature to 140°C and maintain it for 30 min. Cool down and clean to obtain iron-doped cobalt iron phosphate bifunctional electrocatalyst.

[0051] Example 2

[0052] S1. Preparation of positively charged pure nickel foam

[0053] Cutting: 2cm×4cm nickel foam was immersed in 50mL hydrochloric acid solution and ultrasonically cleaned at 30℃ for 10min. After rinsing with deionized water until neutral, the nickel foam was immersed in 30mL CTAB aqueous solution and ultrasonically cleaned for 10min. The nickel foam was then transferred to 50mL anhydrous ethanol solution and ultrasonically cleaned for 5min. After rinsing with deionized water, it was vacuum dried to obtain positively charged pure nickel foam.

[0054] S2. Preparation of negatively charged graphene oxide dispersion

[0055] Weigh 1g of graphene oxide and add it to 500mL of deionized water. Sonicate for 60min, add NaOH solution to adjust the pH to 9, add 0.25g of SDS dispersant, sonicate for 30min, and centrifuge to obtain a negatively charged graphene oxide dispersion.

[0056] S3, Preparation of graphene foam nickel substrate

[0057] Weighing: Vertically immerse the positively charged pure nickel foam into 50 mL of negatively charged graphene oxide dispersion, let it stand at 25 °C for 30 min, then sonicate for 10 min, remove the nickel foam, rinse with deionized water, and dry in a vacuum drying oven at 60 °C for 2 h to obtain the graphene nickel foam substrate material.

[0058] S4. Preparation of precursor solution

[0059] Weigh out 25 parts by weight of cobalt nitrate hexahydrate and 17 parts by weight of ferric nitrate nonahydrate and add them to 40 mL of deionized water. Stir magnetically for 10 min until completely dissolved. Then add 7 parts by weight of sodium hypophosphite and 3 parts by weight of ammonium chloride. Continue stirring for 5 min and then add ammonia dropwise until the pH stabilizes at 9. Continue stirring for 40 min to obtain the precursor solution.

[0060] S5. Preparation of iron-doped cobalt iron phosphate bifunctional electrocatalysts

[0061] Weigh out 90 parts by weight of graphene foam nickel substrate and vertically and completely immerse it in 55 parts of precursor solution. Transfer it to a 100 mL high-pressure reactor lined with polytetrafluoroethylene. After sealing, place it in a microwave reaction chamber and rapidly raise the temperature of the reaction chamber to 120 °C. Microwave treat for 5 min, then continue to raise the temperature to 150 °C and maintain for 30 min. Cool down and clean to obtain iron-doped cobalt iron phosphate bifunctional electrocatalyst.

[0062] Example 3

[0063] S1. Preparation of positively charged pure nickel foam

[0064] Cutting: 2cm×4cm nickel foam was immersed in 50mL hydrochloric acid solution and ultrasonically cleaned at 35℃ for 10min. After rinsing with deionized water until neutral, the nickel foam was immersed in 30mL CTAB aqueous solution and ultrasonically cleaned for 10min. The nickel foam was then transferred to 50mL anhydrous ethanol solution and ultrasonically cleaned for 5min. After rinsing with deionized water, it was vacuum dried to obtain positively charged pure nickel foam.

[0065] S2. Preparation of negatively charged graphene oxide dispersion

[0066] Weigh 1g of graphene oxide and add it to 500mL of deionized water. Sonicate for 60min, add NaOH solution to adjust the pH to 9, add 0.25g of SDS dispersant, sonicate for 30min, and centrifuge to obtain a negatively charged graphene oxide dispersion.

[0067] S3, Preparation of graphene foam nickel substrate

[0068] Weighing: Vertically immerse the positively charged pure nickel foam into 50 mL of negatively charged graphene oxide dispersion, let it stand at 25 °C for 30 min, then sonicate for 10 min, remove the nickel foam, rinse with deionized water, and dry in a vacuum drying oven at 60 °C for 2 h to obtain the graphene nickel foam substrate material.

[0069] S4. Preparation of precursor solution

[0070] Weigh out 30 parts by weight of cobalt nitrate hexahydrate and 20 parts by weight of ferric nitrate nonahydrate, add them to 40 mL of deionized water, and stir magnetically for 10 min until completely dissolved. Then add 10 parts of sodium hypophosphite and 5 parts of ammonium chloride, continue stirring for 5 min, and then add ammonia dropwise until the pH stabilizes at 9. Continue stirring for 40 min to obtain the precursor solution.

[0071] S5. Preparation of iron-doped cobalt iron phosphate bifunctional electrocatalysts

[0072] Weigh out 100 parts by weight of graphene foam nickel substrate and vertically and completely immerse it in 69 parts of precursor solution. Transfer it to a 100 mL high-pressure reactor lined with polytetrafluoroethylene, seal it and place it in a microwave reaction chamber. Rapidly raise the temperature of the reaction chamber to 120°C, microwave it for 5 min, and then continue to raise the temperature to 160°C and maintain it for 30 min. Cool it down and clean it to obtain iron-doped cobalt iron phosphate bifunctional electrocatalyst.

[0073] Comparative Example 1

[0074] The difference between this comparative example and Example 3 is that step S1 is omitted, and the positively charged pure nickel foam in step S3 is replaced with nickel foam in step S1.

[0075] Comparative Example 2

[0076] The difference between this comparative example and Example 3 is that step S2 is omitted, and the graphene in step S2 is used instead of the negatively charged graphene oxide dispersion in step S3.

[0077] Comparative Example 3

[0078] The difference between this comparative example and Example 3 is that step S4 is omitted. 30 parts of cobalt nitrate hexahydrate and 20 parts of ferric nitrate nonahydrate are added to 40 mL of deionized water and magnetically stirred for 10 min until completely dissolved. Then, 10 parts of sodium hypophosphite and 5 parts of ammonium chloride are added and stirred for another 5 min. Ammonia is then added dropwise until the pH stabilizes at 9, and stirring is continued for another 40 min. The resulting precursor solution replaces the precursor solution in S5 in equal volume.

[0079] Performance testing:

[0080] The current density of the iron-doped cobalt iron phosphate bifunctional electrocatalysts prepared in Examples 1-3 and Comparative Examples 1-2, and the cobalt phosphate bifunctional electrocatalyst prepared in Comparative Example 3 were determined in accordance with the standard GB / T 20042.6-2024 "Proton exchange membrane fuel cells - Part 6: Test methods for bipolar plate characteristics".

[0081] The specific surface area of ​​the iron-doped cobalt iron phosphate bifunctional electrocatalysts prepared in Examples 1-3 and Comparative Examples 1-2, and the cobalt phosphate bifunctional electrocatalyst prepared in Comparative Example 3 were determined according to the standard GB / T 20042.4-2009 "Proton exchange membrane fuel cells - Part 4: Electrocatalyst test methods".

[0082] The iron-doped cobalt iron phosphate bifunctional electrocatalysts prepared in Examples 1-3 and Comparative Examples 1-2, as well as the cobalt phosphate bifunctional electrocatalyst prepared in Comparative Example 3, were tested for constant current according to the standard GB / T 17848-1999 "Test Method for Electrochemical Performance of Sacrificial Anodes".

[0083] The iron-doped cobalt iron phosphate bifunctional electrocatalysts prepared in Examples 1-3 and Comparative Examples 1-2, and the cobalt phosphate bifunctional electrocatalyst prepared in Comparative Example 3, were subjected to constant current stability tests for hydrogen evolution reaction and oxygen evolution reaction in water electrolysis in an alkaline electrolyte for 50 h. The specific test results are shown in Table 1 below:

[0084] Table 1 - Performance Test Data of Samples

[0085]

[0086] Data Analysis:

[0087] Comparative analysis of the data in Table 1 above shows that the specific surface area of ​​the iron-doped cobalt iron phosphate bifunctional electrocatalyst prepared in this invention is 220 m². 2 / g, the initial potential for hydrogen evolution through water electrolysis in an alkaline electrolyte is -0.115V and the current density is -22mA / cm. 2 The potential after 50 hours of electrolysis is -0.130V; the initial potential for the oxygen evolution reaction in water electrolysis in alkaline electrolyte is 1.560V, and the current density is 250A / cm². 2 The potential after 50 hours of electrolysis is 1.615V;

[0088] Compared with the examples, Comparative Examples 1 and 2 show that the graphene foam nickel substrate can significantly increase the specific surface area of ​​the iron-doped cobalt iron phosphate bifunctional electrocatalyst. This indicates that the combination of the porosity of the foam nickel and the high surface area of ​​graphene can form a multi-level channel system, which allows the active components of the catalyst to be uniformly dispersed and expose more active sites. The multiple active sites can reduce the potential required for the hydrogen evolution reaction and also provide more reaction interfaces for the oxygen evolution reaction, thereby improving the catalytic efficiency.

[0089] Compared with the examples, the iron-doped cobalt iron phosphate bifunctional electrocatalyst exhibited a lower onset potential and a higher current density in both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), indicating that iron doping can improve the HER and OER performance of the cobalt iron phosphate bifunctional electrocatalyst. Furthermore, after 50 hours of constant current testing, the catalyst potential of the iron-doped cobalt iron phosphate bifunctional electrocatalyst showed only a slight decay, indicating its excellent stability in both HER and OER reactions.

[0090] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. An iron-doped cobalt iron phosphate bifunctional electrocatalyst, characterized in that, It comprises the following components by weight: 80-100 parts of graphene foam nickel substrate and 44-69 parts of precursor solution; The precursor solution comprises the following components by weight: 20-30 parts cobalt salt, 15-20 parts iron salt, 5-10 parts sodium hypophosphite, 2-5 parts ammonium chloride, and 2-4 parts ammonia.

2. The iron-doped cobalt iron phosphate bifunctional electrocatalyst according to claim 1, characterized in that, The graphene-coated nickel foam substrate is obtained through the following steps: A1. Immerse the nickel foam in hydrochloric acid solution and ultrasonically clean it at 25-35℃ for 10 minutes. Rinse it with deionized water until neutral. Then immerse the nickel foam in CTAB aqueous solution and ultrasonically clean it for 10 minutes. Transfer the nickel foam to anhydrous ethanol solution and ultrasonically clean it for 5 minutes. Rinse it with deionized water and vacuum dry it to obtain pure nickel foam with a positive charge. A2. Add graphene oxide to deionized water, sonicate for 60 min, add NaOH solution to adjust pH to 9-10, add SDS dispersant, sonicate for 30 min, centrifuge to obtain negatively charged graphene oxide dispersion. A3. The positively charged pure nickel foam is vertically immersed in the negatively charged graphene oxide dispersion. After standing at 25°C for 30 min, it is ultrasonically treated for 10 min. The nickel foam is then removed, rinsed with deionized water, and dried in a vacuum drying oven at 60°C for 2 h to obtain the graphene nickel foam substrate material.

3. The iron-doped cobalt iron phosphate bifunctional electrocatalyst according to claim 1, characterized in that, The precursor solution is prepared as follows: First, cobalt salt and iron salt are added to 40 mL of deionized water and magnetically stirred for 10 min until completely dissolved. Then, ammonium chloride and sodium hypophosphite are added and stirred for another 5 min. Ammonia water is added dropwise until the pH stabilizes at 9-10, and stirring is continued for another 40 min to obtain the precursor solution.

4. The iron-doped cobalt iron phosphate bifunctional electrocatalyst according to claim 2, characterized in that, In step A1, the size of the nickel foam is 2cm×4cm, and the volume ratio of hydrochloric acid solution, CTAB aqueous solution and anhydrous ethanol is 5:3:

5. The concentration of the hydrochloric acid solution is 3wt%, and the concentration of the CTAB aqueous solution is 0.5wt%.

5. The iron-doped cobalt iron phosphate bifunctional electrocatalyst according to claim 2, characterized in that, In step A2, the ratio of graphene oxide, deionized water, and SDS dispersant is 1g:500mL:0.25g, the concentration of SDS dispersant is 0.05wt%, and the concentration of NaOH solution is 0.4wt%.

6. The iron-doped cobalt iron phosphate bifunctional electrocatalyst according to claim 2, characterized in that, In step A3, the ratio of positively charged pure nickel foam to negatively charged graphene oxide dispersion is 1 g: 50 mL.

7. The iron-doped cobalt iron phosphate bifunctional electrocatalyst according to claim 3, characterized in that, The cobalt salt and iron salt are cobalt nitrate hexahydrate and ferric nitrate nonahydrate, respectively, and the concentration of the ammonia solution is 25 wt%.

8. A method for preparing an iron-doped cobalt iron phosphate bifunctional electrocatalyst according to any one of claims 1-7, characterized in that, The process includes the following steps: vertically and completely immersing a graphene foam nickel substrate in a precursor solution, transferring it to a 100 mL polytetrafluoroethylene-lined high-pressure reactor, sealing it, placing it in a microwave reaction chamber, rapidly raising the temperature of the reaction chamber to 120°C, microwave treating it for 5 min, then continuing to raise the temperature to 140-160°C and maintaining it for 30 min, cooling and cleaning to obtain an iron-doped cobalt iron phosphate bifunctional electrocatalyst.

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