Phosphorus-doped metal nitride-carbide-bimetallic phosphide heterostructure electrocatalyst, preparation method and application thereof

Abstract

The embodiment of the application discloses a phosphorus-doped metal-nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst and a preparation method and application thereof; the preparation method comprises the following steps: S1, preparing a double-metal double-layer hydroxide coated foam nickel; the bimetallic metal is iron and cobalt; S2, preparing a metal-organic framework material coated double-metal double-layer hydroxide coated foam nickel; S3, phosphorizing the metal-organic framework material coated double-metal double-layer hydroxide coated foam nickel to obtain the phosphorus-doped metal-nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst; the metal-nitrogen-carbon compound is a cobalt-nitrogen-carbon compound. The heterostructure of different transition metal compounds is constructed, and a coupling doping method is used, so that the excellent bimetallic phosphide and phosphorus-doped metal-nitrogen-carbon compound heterostructure catalyst is obtained, the catalyst has high HER, OER and ORR catalytic performance, and is expected to be applied to the fields of water electrolysis hydrogen production, metal-air batteries and fuel cells.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalyst technology, specifically relating to phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalysts, their preparation methods, and applications. Background Technology

[0002] Growing energy demands and environmental concerns have spurred increased attention to the production, storage, and utilization of renewable energy. Rechargeable metal-air batteries, fuel cells, and electrochemical water splitting are promising technologies for clean and renewable energy conversion and storage, attracting widespread interest. However, the slow kinetics and large overpotentials in the electrochemical oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) significantly hinder the achievement of high energy efficiency and power output in various related applications. Therefore, ideal electrocatalysts with high activity, high stability, and low cost are crucial for accelerating the redox kinetics of electrochemical processes.

[0003] To date, noble metal catalysts, such as Pt-based and Ru / Ir-based catalysts, remain commercially available catalysts for the electrochemical oxygen reduction reaction, oxygen evolution reaction, and hydrogen evolution reaction. However, noble metal catalysts are not only expensive and lack long-term durability, but their catalytic activity is also limited, restricting their further development.

[0004] In recent years, transition metals and their compounds have been considered as potential substitutes for precious metals due to their abundant reserves, tunable catalytic performance, and low price. However, the catalytic activity, stability, and multifunctionality of unregulated transition metals and their compounds cannot meet the application requirements. Summary of the Invention

[0005] In view of this, some embodiments disclose a method for preparing a phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst, the preparation method including:

[0006] S1. Prepare bimetallic bilayer hydroxide-coated nickel foam; wherein the bimetal is iron and cobalt;

[0007] S2. Preparation of metal-organic framework material coated with bimetallic double-layer hydroxide coated nickel foam;

[0008] S3. Phosphate nickel foam coated with a metal-organic framework material and a bimetallic double-layer hydroxide to obtain a phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst; the metal nitrogen-carbon compound is a cobalt-nitrogen-carbon compound.

[0009] Furthermore, some embodiments disclose a method for preparing a phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst, wherein step S1, preparing bimetallic bilayer hydroxide-coated nickel foam, includes:

[0010] S1-1. Iron salt, cobalt salt and urea are prepared into a first solution in a molar ratio of 1:1 to 2:5 to 10; wherein the iron salt and the cobalt salt have the same type of anion;

[0011] S1-2, Add a solution with a concentration of 0.2–0.5 mol / L to the first solution. -1 Add the intercalating agent and stir.

[0012] S1-3. The first solution and nickel foam are placed in a reaction vessel and kept at 100-200℃ for 6-10 hours to obtain bimetallic bilayer hydroxide-coated nickel foam, wherein the thickness of the bimetallic bilayer hydroxide layer coated on the nickel foam is 10-50 nm.

[0013] Some embodiments disclose a method for preparing phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalysts, wherein the intercalating agent is ammonium fluoride, sodium carbonate, dimethyl sulfoxide, or tetrapropylammonium hydroxide.

[0014] Some embodiments disclose a method for preparing phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalysts. Step S2, preparing metal-organic framework material-coated bimetallic double hydroxide-coated nickel foam, includes:

[0015] S2-1. Dissolve cobalt salt and 2-methylimidazole in a mixture of alcohol and deionized water at a molar ratio of 1:5-15 to prepare a cobalt salt concentration of 0.05 mol / L. -1 The second solution; the alcohol solution is methanol, ethanol or isopropanol, and the volume ratio of the alcohol solution to deionized water is 1:1 to 3;

[0016] S2-2. Place bimetallic bilayer hydroxide-coated nickel foam in a second solution and stir the second solution using a magnetic stirrer at a speed of 100-300 rpm for 6-24 hours to obtain bimetallic bilayer hydroxide-coated nickel foam with a metal-organic framework material; wherein the metal-organic framework material is ZIF-67 particles with a size of 100-1000 nm.

[0017] The preparation method of the phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst disclosed in some embodiments includes step S3:

[0018] A phosphorus-containing material and a metal-organic framework material-coated bimetallic double-layer hydroxide-coated nickel foam are placed in a tube furnace and subjected to a one-step phosphating reaction at 400–500 °C under a protective atmosphere to obtain a phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst. The phosphorus-containing material is elemental phosphorus, NaH2PO2·H2O, POCl3, PCl3, or P2O5, and the protective atmosphere is a mixture of argon, nitrogen, and hydrogen in a volume ratio of 1:0–0.1:0–0.5.

[0019] Some embodiments disclose a method for preparing phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalysts, wherein the heating rate of the one-step phosphating reaction is controlled at 2–5 °C / min. -1 The holding time at the reaction temperature is set to 1-2 hours.

[0020] Some embodiments disclose a method for preparing a phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst. In step S1-1, the cobalt salt includes cobalt nitrate, cobalt sulfate, or cobalt chloride; the iron salt includes ferric nitrate, ferric sulfate, or ferric chloride.

[0021] In some embodiments, a method for preparing a phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst is disclosed. In step S2-1, the cobalt salt includes cobalt nitrate, cobalt sulfate, or cobalt chloride.

[0022] On the other hand, some embodiments disclose phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalysts, which are obtained by the preparation method of the phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalysts disclosed in the embodiments of the present invention.

[0023] On the other hand, some embodiments disclose the application of phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalysts for electrochemical oxygen reduction reaction, oxygen evolution reaction and hydrogen evolution reaction.

[0024] The present invention discloses a phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst, its preparation method, and its application. It constructs heterostructures of different transition metal compounds and couples doping methods to obtain high-performance bimetallic phosphide and phosphorus-doped metal nitrogen-carbon compound heterostructure catalysts. This catalyst is a trifunctional electrocatalyst with highly efficient HER, OER, and ORR catalytic performance, and is expected to be applied in fields such as water electrolysis for hydrogen production and metal-air batteries / fuel cells. Attached Figure Description

[0025] Figure 1 Flowchart of the preparation method in Example 1;

[0026] Figure 2 SEM images of CoFeLDH@NF disclosed in Example 1;

[0027] Figure 3 SEM images of ZIF-67@CoFe LDH@NF disclosed in Example 1;

[0028] Figure 4 SEM images of Co-NCP@CoFeP@NF disclosed in Example 1;

[0029] Figure 5 LSV curves of Co-NCP@CoFeP@NF for HER testing disclosed in Example 1;

[0030] Figure 6 LSV curves of Co-NCP@CoFeP@NF for OER testing disclosed in Example 1;

[0031] Figure 7 LSV curves of Co-NCP@CoFeP@NF disclosed in Example 1 for ORR testing. Detailed Implementation

[0032] The term "embodiment" used herein, as an example, is not necessarily to be construed as superior to or better than other embodiments. Performance testing in these embodiments of the invention, unless otherwise specified, employs conventional testing methods in the art. It should be understood that the terminology used in these embodiments is merely for describing particular implementations and is not intended to limit the scope of the disclosure of these embodiments.

[0033] Unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this invention pertain; other experimental methods and technical means not specifically noted in the embodiments of this invention refer to experimental methods and technical means commonly used by one of ordinary skill in the art.

[0034] The terms “basic” and “approximately” used in this document are to describe small fluctuations. For example, they can mean less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ±0.1%, such as less than or equal to ±0.05%. Numerical data presented or expressed in range format in this document are used for convenience and brevity only, and should therefore be flexibly interpreted to include not only the explicitly listed values ​​that define the range, but also all independent values ​​or subranges contained within that range. For example, a numerical range of “1–5%” should be interpreted to include not only the explicitly listed values ​​from 1% to 5%, but also the independent values ​​and subranges within the indicated range. Thus, this numerical range includes independent values ​​such as 2%, 3.5%, and 4%, and subranges such as 1%–3%, 2%–4%, and 3%–5%, etc. This principle also applies to ranges that list only one value. Furthermore, this interpretation applies regardless of the width of the range or the characteristics described.

[0035] In this document, including in the claims, conjunctions such as "comprising," "including," "with," "having," "containing," "involving," and "accommodating" are understood to be open-ended, meaning "including but not limited to." Only the conjunctions "consisting of" and "composed of" are closed conjunctions.

[0036] To better illustrate the content of this invention, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that the invention can be practiced even without certain specific details. In the embodiments, some methods, means, instruments, and devices well-known to those skilled in the art are not described in detail, in order to highlight the main points of the invention.

[0037] Without conflict, the technical features disclosed in the embodiments of the present invention can be combined arbitrarily, and the resulting technical solution belongs to the content disclosed in the embodiments of the present invention.

[0038] In some embodiments, the preparation method of the phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst includes:

[0039] S1. Prepare bimetallic bilayer hydroxide-coated nickel foam; wherein the bimetal is iron and cobalt;

[0040] S2. Preparation of metal-organic framework material coated with bimetallic double-layer hydroxide coated nickel foam;

[0041] S3. Phosphate nickel foam coated with a metal-organic framework material and a bimetallic double-layer hydroxide to obtain a phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst; the metal nitrogen-carbon compound is a cobalt-nitrogen-carbon compound.

[0042] Furthermore, some embodiments disclose a method for preparing a phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst, wherein step S1, preparing bimetallic bilayer hydroxide-coated nickel foam, includes:

[0043] S1-1. Iron salt, cobalt salt, and urea are prepared into a first solution at a molar ratio of 1:1 to 2:5 to 10; wherein the iron salt and the cobalt salt have the same anion; wherein the urea provides an alkaline environment for the reaction system, which is conducive to the formation of bimetallic hydroxides; generally, the cobalt salt includes cobalt nitrate, cobalt sulfate, or cobalt chloride; the iron salt includes ferric nitrate, ferric sulfate, or ferric chloride.

[0044] S1-2, Add a solution with a concentration of 0.2–0.5 mol / L to the first solution. -1 Add the intercalating agent and stir. Generally, the type and concentration of the intercalating agent have a significant impact on the morphology of the bimetallic hydroxide. For example, intercalating agents that can be selected include ammonium fluoride, sodium carbonate, dimethyl sulfoxide, or tetrapropylammonium hydroxide.

[0045] S1-3. The first solution and nickel foam are placed in a reaction vessel and kept at 100–200℃ for 6–10 h to obtain bimetallic bilayer hydroxide-coated nickel foam. Scanning electron microscopy reveals that the thickness of the bimetallic bilayer hydroxide layer on the nickel foam is 10–50 nm. In this paper, cobalt-iron bimetallic bilayer hydroxide-coated nickel foam can be labeled as CoFe LDH@NF. Typically, the mixture of the first solution and the intercalating agent is uniformly stirred and then placed together with the pre-treated nickel foam in a reaction vessel. The reaction is kept at 100–200℃ for 6–10 h. By adjusting the ratio of raw materials and the type and concentration of the intercalating agent, the morphology of the prepared bimetallic hydroxide can exhibit different variations such as nanorods, nanosheets, nanoflowers, or nanospheres. For example, CoFe LDH nanosheets with a thickness of 10–50 nm can be prepared, exhibiting good catalytic activity. Usually, the prepared CoFe LDH@NF also needs to be washed and dried in a vacuum drying oven.

[0046] Some embodiments disclose a method for preparing phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalysts, wherein the intercalating agent is ammonium fluoride, sodium carbonate, dimethyl sulfoxide, or tetrapropylammonium hydroxide.

[0047] Some embodiments disclose a method for preparing phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalysts. Step S2, preparing metal-organic framework material-coated bimetallic double hydroxide-coated nickel foam, includes:

[0048] S2-1. Dissolve cobalt salt and 2-methylimidazole in a mixture of alcohol and deionized water at a molar ratio of 1:5-15 to prepare a cobalt salt concentration of 0.05 mol / L. -1 The second solution; the alcohol solution is methanol, ethanol or isopropanol, and the volume ratio of the alcohol solution to deionized water is 1:1 to 3; generally, cobalt salts include cobalt nitrate, cobalt sulfate or cobalt chloride;

[0049] In some embodiments, the cobalt salt used to prepare the second solution is the same as the cobalt salt used to prepare the first solution;

[0050] S2-2. Bimetallic bilayer hydroxide-coated nickel foam was placed in a second solution and stirred using a magnetic stirrer at a speed of 100–300 rpm for 6–24 hours to obtain metal-organic framework-coated bimetallic bilayer hydroxide-coated nickel foam. The metal-organic framework material was ZIF-67 particles, and the size of the ZIF-67 particles was observed to be 100–1000 nm using scanning electron microscopy. In this paper, the metal-organic framework-coated bimetallic bilayer hydroxide-coated nickel foam is labeled ZIF-67@CoFe LDH@NF.

[0051] Typically, the concentration ratio of cobalt salt to 2-methylimidazole is crucial for the formation of ZIF-67 particles. Insufficient 2-methylimidazole results in low ZIF-67 formation, reducing the catalytic active sites for ORR; excessive 2-methylimidazole causes the ZIF-67 particles to completely cover the active sites of CoFe LDH, reducing the catalytic active sites for HER / OER.

[0052] The volume ratio of alcohol solution to deionized water and the reaction time also significantly affect the growth of ZIF-67 particles. Typically, the nucleation reaction between cobalt salt and 2-methylimidazole is rapid in deionized water but slow in alcohol solution. Therefore, a suitable volume ratio of alcohol solution to deionized water is used to control the coordination rate, and the reaction time must be carefully controlled. Generally, the alcohol solution is methanol, ethanol, or isopropanol, and the volume ratio of alcohol solution to deionized water is 1:1 to 3.

[0053] Furthermore, the stirring rate is also a crucial factor, significantly influencing the size of ZIF-67 particles. Slower stirring rates result in larger ZIF-67 particles, while faster rates lead to smaller particles. Ideally, the size of the ZIF-67 particles should match the size of the CoFe LDH nanosheets to facilitate the formation of heterostructures; excessively large or small size differences hinder this process. In summary, controlling the concentration ratio of the raw materials, the volume ratio of alcohol solution to deionized water in the mixed solution, and the reaction time are essential to maintain the ZIF-67 particle size between 100 and 1000 nm. Additionally, a suitable ZIF-67 particle loading must be maintained to ensure uniform embedding of the particles within the CoFe LDH nanosheets without completely covering the active sites.

[0054] Typically, the prepared ZIF-67@CoFe LDH@NF also needs to be dried in a vacuum drying oven.

[0055] The preparation method of the phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst disclosed in some embodiments includes step S3:

[0056] A phosphorus-containing material and a metal-organic framework material-coated bimetallic double-layer hydroxide-coated nickel foam are placed in a tube furnace and subjected to a one-step phosphating reaction at 400–500 °C under a protective atmosphere to obtain a phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst. The phosphorus-containing material is elemental phosphorus, NaH2PO2·H2O, POCl3, PCl3, or P2O5, and the protective atmosphere is a mixture of argon, nitrogen, and hydrogen in a volume ratio of 1:0–0.1:0–0.5.

[0057] Generally, proper matching of phosphorus-containing substances with the protective atmosphere for phosphating reactions plays a crucial role.

[0058] In some embodiments, to improve productivity, if the phosphorus-containing material contains low-valence phosphorus, such as elemental phosphorus or NaH2PO2·H2O, a mixed gas containing a certain proportion of argon, nitrogen, and hydrogen is used, wherein the nitrogen and hydrogen content is close to zero, which can achieve rapid phosphating. However, rapid phosphating can easily lead to structural instability and even affect catalytic activity. As an optional embodiment, the volume ratio of argon, nitrogen, and hydrogen in the mixed gas is 1:0.001~0.01:0.001~0.02.

[0059] In some embodiments, to improve catalytic activity and appropriate stability, it is necessary to control the amount of nitrogen doping and the phosphating rate. Substances containing intermediate-valence phosphorus, such as NaH₂PO₂·H₂O, POCl₃, and PCl₃, are selected and combined with a mixed gas containing a certain proportion of argon, nitrogen, and hydrogen. The proportions of nitrogen and hydrogen are relatively small, which can improve catalytic activity while ensuring appropriate structural stability. As an optional embodiment, the volume ratio of argon, nitrogen, and hydrogen in the mixed gas is 1:0.01–0.05:0.02–0.2.

[0060] In some embodiments, in order to achieve ultra-high stability, phosphorus-containing substances with high valence phosphorus, such as PCl3 and P2O5, can be selected and combined with a mixed gas containing a certain proportion of argon, nitrogen and hydrogen. The proportion of nitrogen and hydrogen is relatively high, which can ensure ultra-high structural stability while having a certain catalytic activity.

[0061] As an optional embodiment, the volume ratio of argon, nitrogen, and hydrogen in the mixed gas is 1:0.05-0.1:0.2-0.5.

[0062] In this embodiment, the phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst is labeled Co-NCP@CoFeP@NF. Typically, NaH2PO2·H2O particles are placed upstream of a tube furnace, and ZIF-67@CoFe LDH@NF is placed downstream. At the reaction temperature, NaH2PO2·H2O generates sufficient PH3 gas, which reacts with ZIF-67@CoFe LDH@NF to form Co-NCP@CoFeP@NF.

[0063] In some embodiments, the heating rate of the one-step phosphating reaction is controlled at 2–5 °C / min. -1 The holding time at the reaction temperature was set to 1–2 hours. Generally, the heating rate has a significant impact on the catalyst morphology. An excessively rapid heating rate will lead to catalyst morphology collapse, which is detrimental to the catalyst's catalytic activity and stability. The holding temperature is crucial for the catalyst. Too low a temperature will not decompose phosphorus-containing substances to produce sufficient phosphorus-containing gases, while too high a temperature will result in an excessively rapid decomposition rate of phosphorus-containing substances, making it difficult to fully react with ZIF-67@CoFe LDH@NF. Furthermore, CoFe LDH will decompose at higher temperatures, leading to a decrease in the OER activity of the electrocatalyst. Too short a holding time will result in insufficient phosphating of ZIF-67@CoFe LDH@NF, while too long a holding time will increase preparation time and energy consumption. In addition, the one-step phosphating method not only shortens the experimental process but also allows phosphorus doping to modulate the local electron configuration of CoFeP and Co-NCP metal atoms, optimizing the catalyst's adsorption / desorption capacity for reaction intermediates at active sites, which helps to further improve the catalyst's HER, OER, or ORR performance.

[0064] On the other hand, some embodiments disclose phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalysts, which are obtained by the preparation method of the phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalysts disclosed in the embodiments of the present invention. The phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst can be labeled Co-NCP@CoFeP@NF. Bimetal refers to iron and cobalt, bimetallic phosphide refers to iron-cobalt phosphide (CoFeP), phosphorus-doped metal nitrogen-carbon compound refers to phosphorus-doped cobalt nitrogen-carbon compound (Co-NCP), and NF is nickel foam. The structure of this electrocatalyst is as follows: iron-cobalt phosphide (CoFeP) is coated on nickel foam to form CoFeP nanosheets, and Co-NCP is coated on the CoFeP nanosheets to form Co-NCP particle layers. The three-dimensional structure of the nickel foam provides a porous base, which is beneficial not only for the contact between the catalyst and the reactants but also for gas transport. The two-dimensional CoFeP nanosheets are stably anchored on the nickel foam, and the Co-NCP particles are dispersedly embedded between the CoFeP nanosheets, forming a stable heterostructure. This stable heterostructure can resist the rapid generation and desorption of bubbles during the reaction, which helps maintain the stable catalytic performance of the electrocatalyst.

[0065] On the other hand, some embodiments disclose the application of phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalysts for electrochemical oxygen reduction reaction, oxygen evolution reaction and hydrogen evolution reaction.

[0066] The technical details are further illustrated below with reference to the embodiments.

[0067] Example 1

[0068] In Example 1, as Figure 1 As shown, the preparation method of phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst includes:

[0069] S1. Preparation of bimetallic double-layer hydroxide-coated nickel foam; specifically including:

[0070] S1-1. Prepare the first solution by mixing iron salt, cobalt salt and urea in a molar ratio of 1:1:5.

[0071] S1-2, Add a solution with a concentration of 0.2 mol / L to the first solution. -1 Sodium carbonate, the intercalating agent;

[0072] S1-3. The first solution and nickel foam were placed in a reaction vessel and kept at 100℃ for 6 hours to obtain bimetallic bilayer hydroxide-coated nickel foam, labeled as CoFe LDH@NF; wherein the thickness of the bimetallic bilayer hydroxide layer on the nickel foam was 10 nm; the scanning electron microscope image of CoFe LDH@NF is shown below. Figure 2 As shown;

[0073] S2. Preparation of metal-organic framework materials coated with bimetallic bilayer hydroxide-coated nickel foam; specifically including:

[0074] S2-1. Dissolve cobalt salt and 2-methylimidazole in a mixture of methanol and deionized water at a molar ratio of 1:5 to prepare a second solution; the volume ratio of methanol to deionized water is 1:3.

[0075] S2-2. The bimetallic bilayer hydroxide-coated nickel foam was placed in a second solution. The second solution was stirred using a magnetic stirrer at 100 rpm for 6 hours to obtain a metal-organic framework material-coated bimetallic bilayer hydroxide-coated nickel foam, denoted as ZIF-67@CoFe LDH@NF. Its morphology under a scanning electron microscope is shown below. Figure 3 As shown;

[0076] S3. Phosphating nickel foam coated with a metal-organic framework material and a bimetallic double-layer hydroxide coating yields a phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst; specifically including:

[0077] 1g of white NaH2PO2·H2O granules were placed in the upstream section of a tube furnace, while bimetallic double-layer hydroxide-coated nickel foam was placed in the downstream section. The furnace was heated at 2℃ for 1 minute. -1 The temperature is increased to 400℃ and a one-step phosphating reaction is carried out in a protective atmosphere, which is a mixture of argon, nitrogen and hydrogen with a volume ratio of 1:0.01:0.02.

[0078] A phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst, labeled Co-NCP@CoFeP@NF, was obtained. Its morphology under scanning electron microscopy is shown below. Figure 4 As shown;

[0079] The HER performance of Co-NCP@CoFeP@NF prepared in Example 1 was tested. The test conditions included: the working electrode, counter electrode, and reference electrode were Co-NCP@CoFeP@NF, a carbon rod, and Hg / HgO (1M KOH), respectively; the solution was a 1M KOH solution saturated with nitrogen or argon; and the test was conducted at room temperature.

[0080] Test LSV curve as follows Figure 5 As shown.

[0081] The OER performance of Co-NCP@CoFeP@NF prepared in Example 1 was tested. The test conditions included: the working electrode, counter electrode, and reference electrode were Co-NCP@CoFeP@NF, a carbon rod, and Hg / HgO (1M KOH), respectively. The solution was an oxygen-saturated 1M KOH solution. The test was conducted at room temperature.

[0082] Test LSV curve as follows Figure 6 As shown.

[0083] ORR performance of Co-NCP@CoFeP@NF prepared in Example 1 was tested. The test conditions included: working electrode, counter electrode, and reference electrode were Co-NCP@CoFeP@NF, carbon rod, and Hg / HgO (1M KOH), respectively; the solution was 0.1M KOH solution saturated with oxygen; the solution was placed on a magnetic stirrer at 500 rpm; and the test was conducted at room temperature.

[0084] Test LSV curve as follows Figure 7 As shown.

[0085] In summary, the preparation method of the phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst disclosed in this embodiment has the following beneficial technical effects:

[0086] (1) Low cost: Transition metals are abundant in the Earth's crust and have the advantage of being inexpensive compared to precious metals; in addition, the preparation process is simple and the preparation of Co-NCP@CoFeP@NF catalysts is scalable.

[0087] (2) Excellent performance: The Co-NCP@CoFeP@NF catalyst has a low overpotential for HER and OER, and the onset potential for ORR is also very low, indicating that the catalyst has excellent trifunctional catalytic performance of HER, OER and ORR.

[0088] (3) Stable structure: Co-NCP@CoFeP@NF catalyst has a unique structure; the three-dimensional nickel foam NF provides a porous structure, which is not only conducive to the contact between the catalyst and the reactants, but also to the gas transport; the two-dimensional CoFeP nanosheets are stably anchored on NF, and the Co-NCP particles are dispersedly embedded between the CoFeP nanosheets; the stable structure can resist the rapid generation and desorption of bubbles during the reaction process.

[0089] (4) Multifunctionality: Due to its HER / OER / ORR catalytic activity, the Co-NCP@CoFeP@NF catalyst can be used in a variety of applications. For example, it can be used as a catalyst for water electrolysis to produce hydrogen and oxygen, and it can also be used as an air cathode material in zinc-air batteries. This multifunctionality gives the Co-NCP@CoFeP@NF catalyst broad potential in practical applications and allows it to adapt to different needs.

[0090] This invention discloses a phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst, its preparation method, and its applications. It constructs heterostructures of different transition metal compounds and couples doping methods to obtain high-performance bimetallic phosphide and phosphorus-doped metal nitrogen-carbon compound heterostructure catalysts. These catalysts are trifunctional electrocatalysts with highly efficient HER / OER / ORR catalytic performance, and are expected to be applied in fields such as water electrolysis for hydrogen production and metal-air batteries / fuel cells.

[0091] The technical solutions and technical details disclosed in the embodiments of this invention are merely illustrative of the inventive concept of this invention and do not constitute a limitation on the technical solutions of the embodiments of this invention. Any conventional changes, substitutions, or combinations made to the technical details disclosed in the embodiments of this invention have the same inventive concept as this invention and are within the protection scope of the claims of this invention.

Claims

1. A method for preparing a phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst, characterized in that, include: S1. Preparation of bimetallic double-layer hydroxide-coated nickel foam; The bimetal is iron and cobalt; comprising: S1-1. Prepare a first solution by mixing iron salt, cobalt salt and urea in a molar ratio of 1:1~2:5~10; wherein the iron salt and the cobalt salt have the same type of anion; S1-2, Add a concentration of 0.2~0.5 mol / L to the first solution. -1 The intercalating agent is stirred; the intercalating agent is ammonium fluoride, sodium carbonate, dimethyl sulfoxide, or tetrapropylammonium hydroxide. S1-3. The first solution and nickel foam are placed in a reaction vessel and kept at 100~200℃ for 6~10h to obtain bimetallic bilayer hydroxide-coated nickel foam, wherein the thickness of the bimetallic bilayer hydroxide layer coated on the nickel foam is 10~50nm. S2. Preparation of metal-organic framework material-coated bimetallic bilayer hydroxide-coated nickel foam; including: S2-1. Dissolve cobalt salt and 2-methylimidazole in a mixture of alcohol and deionized water at a molar ratio of 1:5~15 to prepare a cobalt salt concentration of 0.05 mol / L. -1 The second solution; the alcohol solution is methanol, ethanol or isopropanol, and the volume ratio of the alcohol solution to deionized water is 1:1~3; S2-2. Place the bimetallic bilayer hydroxide-coated nickel foam in a second solution and stir the second solution using a magnetic stirrer at a speed of 100-300 rpm for 6-24 hours to obtain bimetallic bilayer hydroxide-coated nickel foam coated with a metal-organic framework material; wherein the metal-organic framework material is ZIF-67 particles with a particle size of 100-1000 nm. S3. Phosphating a metal-organic framework material coated with a bimetallic double-layer hydroxide coated with nickel foam to obtain a phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst; comprising: placing a phosphorus-containing material and a metal-organic framework material coated with a bimetallic double-layer hydroxide coated with nickel foam in a tube furnace, and carrying out a one-step phosphating reaction at 400~500℃ under a protective atmosphere to obtain a phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst; wherein, the phosphorus-containing material is elemental phosphorus, NaH2PO2·H2O, POCl3, PCl3 or P2O5, and the protective atmosphere is a mixture of argon, nitrogen and hydrogen in a volume ratio of 1:0~0.1:0~0.5; the metal nitrogen-carbon compound is a cobalt-nitrogen-carbon compound.

2. The method for preparing the phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst according to claim 1, characterized in that, The heating rate of the one-step phosphating reaction is controlled at 2~5℃ min. -1 The holding time at the reaction temperature is set to 1~2 hours.

3. The method for preparing the phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst according to claim 1, characterized in that, In step S1-1, the cobalt salt includes cobalt nitrate, cobalt sulfate, or cobalt chloride; the iron salt includes ferric nitrate, ferric sulfate, or ferric chloride.

4. The method for preparing the phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst according to claim 1, characterized in that, In step S2-1, the cobalt salt includes cobalt nitrate, cobalt sulfate, or cobalt chloride.

5. A phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst, characterized in that, It is obtained by the preparation method according to any one of claims 1 to 4.

6. The application of the phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst according to claim 5, characterized in that, The phosphorus-doped metal nitrogen-carbon compound-bimetallic phosphide heterostructure electrocatalyst is used for electrochemical oxygen reduction reaction, oxygen evolution reaction and hydrogen evolution reaction.

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