A P and Fe co-doped Ni3Se4 nanomaterial and its preparation method and application

Abstract

The present invention discloses a kind of P, Fe co-doped Ni3Se4 nanomaterial and preparation method and application, in the case of not adding reducing organic solvent and strong reducing agent, by one-step hydrothermal simultaneously realize the preparation of selenide and the doping of anion and cation.The catalyst is formed by connecting granules of about 50-100nm, and the surface has a hole distribution of different sizes, which can provide a large specific surface area for the reaction and thus expose more active sites, and the interconnected particle morphology is conducive to mass transfer between particles.The preparation method uses selenium powder and red phosphorus as selenium source and phosphorus source respectively, is added into the middle of metal salt solution, and prepares P, Fe co-doped Ni3Se4 catalyst by one-step hydrothermal method.The raw materials and process equipment used in the preparation process are simple, low cost, high yield, conducive to large-scale production, easy to batch preparation, and have broad industrial application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation and application, and relates to a P and Fe co-doped Ni3Se4 nanomaterial, a preparation method of the nanomaterial, and an application of the nanomaterial. Background Art

[0002] Hydrogen energy, as a clean energy source, has long been a focus of attention. Water electrolysis is the simplest process for obtaining high-purity hydrogen. This method uses water as a raw material and is generally powered by renewable energy sources such as solar, wind, and hydropower. The reaction process does not generate any pollutants or carbon-containing compounds, and the resulting hydrogen has a purity of over 99.7%. This method has considerable development potential and has attracted the attention of researchers worldwide. However, the electrocatalytic water splitting method is inefficient and costly. Developing efficient, inexpensive, and stable electrocatalysts to improve water electrolysis efficiency and reduce hydrogen production costs is a bottleneck technology for achieving large-scale application of the electrocatalytic water splitting method.

[0003] Hydrogen production from water electrolysis involves two half-reactions: the cathodic hydrogen evolution reaction (HER) and the anodic oxygen evolution reaction (OER). The electrolysis reaction involves multiple electron transfer processes, particularly the anodic OER, which requires four electron transfers. Each electron transfer requires energy, resulting in slow reaction kinetics and a large overpotential. Therefore, designing efficient and stable OER catalysts is crucial for hydrogen production from water electrolysis. Currently, noble metal OER catalysts, such as RuO2 and IrO2, offer excellent performance. However, their large-scale application is limited by cost and resource scarcity. In the past decade or so, the development of OER catalysts based on transition metal compounds, such as chalcogenides, nitrides, phosphides, and carbides, has attracted significant attention. Transition metal selenides, due to their unique electronic configuration and excellent conductivity, facilitate charge transfer during electrocatalysis, and are considered promising OER catalysts.

[0004] Among them, nickel selenide has great potential in the field of water electrolysis because of its advantages such as abundant reserves, simple preparation, acid and alkali corrosion resistance, and good electrical conductivity. However, there are still some problems with this type of catalyst. For example, the intrinsic activity and stability of nickel selenide are poor, resulting in a high overpotential and a short service life when electrolyzing water for oxygen evolution. Since the electrolysis of water for oxygen evolution reaction involves multiple electron transfer steps and multiple intermediates are produced during the reaction process, single-component catalysts cannot provide efficient active sites for different reactions. Moreover, the preparation process of nickel selenide is often accompanied by the use of organic reducing agents, which makes the subsequent cleaning of the catalyst difficult and causes environmental pollution. Therefore, the above-mentioned problems of nickel-based selenides are the key difficulties in the current application of nickel selenide in electrolyzing water for oxygen evolution. Summary of the Invention

[0005] The purpose of the present invention is to provide a P and Fe co-doped Ni3Se4 nanomaterial and its preparation method and application, and to construct a Ni3Se4 nanomaterial co-doped with anions and cations, which can adjust the electronic structure of Ni3Se4 and optimize the adsorption and desorption of OER intermediates by active sites, thereby improving the conductivity and increasing the active sites; at the same time, further simplifying the synthesis steps, reducing the preparation cost, and ultimately preparing an economical and efficient OER electrocatalyst.

[0006] The first technical solution adopted by the present invention is a method for preparing a P and Fe co-doped Ni3Se4 nanomaterial, which specifically comprises the following steps:

[0007] Step 1: Grind red phosphorus with water to obtain a first turbid solution;

[0008] Step 2: Add appropriate amounts of selenium powder, nickel salt, iron salt, and urea to the first turbid liquid, stir vigorously, and add water to mix evenly to obtain a second turbid liquid;

[0009] Step 3: heating the second turbid liquid, keeping it warm for a certain period of time, and then cooling it to obtain a preliminary product;

[0010] Step 4: The preliminary product is washed and then vacuum dried to finally obtain P and Fe co-doped Ni3Se4 network nanoparticles.

[0011] The characteristics of this technical solution are:

[0012] Calculated by the amount of substance, the amount of red phosphorus used in step 1 is 1-3 mmol; water is deionized water, and the amount of water used in step 1 is 0.1-0.5 mL.

[0013] In step 2, the ratio of nickel salt to iron salt is 1-3:3-1.

[0014] In step 2, the concentration of nickel salt is 1-3 mM, and the concentration of urea is 5-10 mM.

[0015] In step 2, the nickel salt is nickel nitrate hexahydrate, and the iron salt is ferric chloride hexahydrate.

[0016] Calculated by the amount of substance, the ratio of the amount of selenium powder used in step 2 to the amount of red phosphorus used in step 1 is 1:1-2.

[0017] In step 1 and step 2, the total amount of water added is 30-35 mL.

[0018] Step 2: After adding selenium powder, nickel salt, iron salt and urea to the first turbid liquid, the stirring time is 10-60 minutes.

[0019] In step 3, the heating reaction temperature is 150-220° C., and the reaction time is 10-20 h.

[0020] The heating reaction in step 3 is carried out in a polytetrafluoroethylene liner of a high-pressure reactor.

[0021] The specific process of step 4 is: washing the preliminary product with water and ethanol in sequence, and then vacuum drying it in an environment of 55-65° C. to obtain P and Fe co-doped Ni 3 Se 4 nanomaterials.

[0022] The second technical solution of the present invention is a P and Fe co-doped Ni3Se4 nanomaterial, which is obtained by the above-mentioned preparation method. The Ni3Se4 nanomaterial has a network-like nanoparticle morphology.

[0023] The characteristics of this technical solution are:

[0024] Ni3Se4 nanomaterials are made up of connected particles of about 50-100nm, and have holes of varying sizes distributed on the surface.

[0025] The third technical solution of the present invention is to provide the application of the above-mentioned P and Fe co-doped Ni3Se4 nanomaterial as an electrocatalyst for oxygen evolution reaction.

[0026] The beneficial effects of the present invention are as follows:

[0027] 1. Without adding reducing organic solvents and strong reducing agents, the preparation of selenide and the doping of anions and cations were simultaneously achieved through a one-step hydrothermal reaction.

[0028] 2. The catalyst obtained by this preparation method is composed of particles of about 50-100 nm connected together, with pores of varying sizes distributed on the surface, which can provide a large specific surface area for the reaction and thus expose more active sites. The interconnected particle morphology is conducive to mass transfer between particles.

[0029] 3. Doping with anions and cations can modulate the electronic structure and crystallinity of the catalyst, optimize the adsorption capacity of oxygen-containing intermediates, increase the number of active sites, and thus enhance the catalyst's OER performance. Furthermore, oxygen-containing anions can inhibit the precipitation of selenium anions during water electrolysis, improving the stability of the catalyst. The catalyst prepared by this invention exhibits excellent water electrolysis activity and stability and has been successfully applied to oxygen evolution from water electrolysis.

[0030] 4. Preparation Method: Selenium powder and red phosphorus, as the selenium and phosphorus sources, respectively, are added to a metal salt solution to prepare a P- and Fe-co-doped Ni₃Se₄ catalyst via a one-step hydrothermal method. This preparation process utilizes simple raw materials and process equipment, resulting in low cost and high yield, making it suitable for large-scale production and easy to manufacture in batches, with broad prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic flow chart of a method for preparing a P and Fe co-doped Ni3Se4 nanomaterial according to the present invention;

[0032] Figure 2 This is the XRD pattern of the catalyst sample prepared in Example 1 of the present invention;

[0033] Figure 3 This is a SEM image of the catalyst sample prepared in Example 1 of the present invention;

[0034] Figure 4 HRTEM image of the catalyst sample prepared in the embodiment of the present invention and the corresponding element distribution map;

[0035] Figure 5 The linear sweep voltammogram of the OER of the catalyst sample prepared in Example 1 of the present invention in 1M KOH solution;

[0036] Figure 6 This is a linear sweep voltammogram of the OER of the catalyst sample prepared in Example 2 of the present invention in 1 M KOH solution;

[0037] Figure 7 This is a linear sweep voltammogram of the OER of the catalyst sample prepared in Example 3 of the present invention in 1 M KOH solution;

[0038] Figure 8 The linear sweep voltammogram of the OER of the catalyst sample prepared in Example 4 of the present invention in 1M KOH solution;

[0039] Figure 9 XRD pattern of the catalyst sample prepared in Comparative Example 1 of the present invention;

[0040] Figure 10This is a SEM image of the catalyst sample prepared in Comparative Example 1 of the present invention;

[0041] Figure 11 The linear sweep voltammogram of the OER of the catalyst sample prepared in Comparative Example 1 of the present invention in 1M KOH solution;

[0042] Figure 12 The linear sweep voltammogram of the OER of the catalyst sample prepared in Comparative Example 2 of the present invention in 1M KOH solution;

[0043] Figure 13 This is a linear sweep voltammogram of the OER of the catalyst sample prepared in Comparative Example 3 of the present invention in 1 M KOH solution. DETAILED DESCRIPTION

[0044] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] like Figure 1 As shown, the preparation method of a P and Fe co-doped Ni3Se4 nanomaterial of the present invention is implemented according to the following steps:

[0046] Step 1: Grind red phosphorus with water to obtain a first turbid solution; the amount of red phosphorus is 1-3 mmol, and the amount of water is deionized water, and the amount of water used is 0.1-0.5 mL;

[0047] Step 2: Weigh selenium powder, nickel salt, iron salt and urea into a beaker, add the first turbid solution, stir vigorously, then add water and mix well to obtain a second turbid solution;

[0048] Both the nickel salt and the iron salt can be their corresponding hydrates, the nickel salt is nickel nitrate, and the iron salt is ferric chloride. The molar ratio of the nickel salt to the iron salt is 1-3:3-1; the concentration of the nickel salt is 1-3mM, and the concentration of urea is 5-10mM. The molar ratio of the amount of selenium powder used to the amount of red phosphorus used in step 1 is 1:1-2. The stirring time is 10-60min. The amount of selenium powder is 1-2mmol, and the molar ratio of selenium powder to red phosphorus is 1:1-2. In this step, the water is deionized water. In steps 1 and 2, the total amount of deionized water added is 30mL.

[0049] Step 3: Transfer the second turbid liquid into a reactor, heat it, and then cool it to obtain a preliminary product;

[0050] The heating reaction temperature is 150-220° C., and the reaction time is 10-20 hours. The heating reaction is carried out in a polytetrafluoroethylene liner of a high-pressure reactor, and the heating reaction is carried out in a closed reactor.

[0051] Step 4: The preliminary product is washed and then vacuum dried to finally obtain P and Fe co-doped Ni3Se4 network nanoparticles.

[0052] After the reaction is completed, the preliminary product is centrifuged and washed with water and ethanol in sequence, and then vacuum dried in an environment of 55-65°C.

[0053] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further illustrated by the following specific examples.

[0054] Example 1

[0055] Step 1: Take 1.8 mmol of red phosphorus and add 0.5 mL of deionized water in batches for grinding to obtain the first turbid solution;

[0056] Step 2: Weigh 1.2 mmol of selenium powder (Se), 0.45 mmol of nickel nitrate hexahydrate (Ni(NO3)2•6H2O), 0.15 mmol of ferric chloride hexahydrate (FeCl3•6H2O), and 8.3 mmol of urea into a beaker. First, add the first turbid solution, then add 29.5 mL of deionized water, stir vigorously for 60 minutes, and mix thoroughly to obtain a second turbid solution.

[0057] Step 3: Transfer the second turbid liquid to a high-pressure reactor, heat the second turbid liquid to 200° C., keep the temperature for 14 hours, and then cool it to obtain a preliminary product;

[0058] Step 4: The preliminary product was washed with water and ethanol, and then vacuum dried at 60°C to finally obtain P and Fe co-doped Ni3Se4 network nanoparticles.

[0059] like Figure 2 As shown in the figure, XRD characterization was performed on the sample prepared in Example 1 to detect the Ni3Se4 network nanoparticles prepared in Example 1. It can be seen that the diffraction peaks of the Ni3Se4 network nanoparticle sample are consistent with those of the Ni3Se4 standard card, indicating that Ni3Se4 was successfully prepared in the above example.

[0060] like Figure 3 As shown, the sample prepared in Example 1 was characterized by SEM. The SEM image shows that the sample prepared in Example 1 presents a network morphology formed by connecting nanoparticles, and the particle diameter is 50-100 nm.

[0061] like Figure 4 As shown, the morphology of the prepared example 1 is also interconnected particles under the HRTEM image, and its element distribution diagram also shows that various elements are evenly distributed on the particles.

[0062] In order to verify the effect of the Ni3Se4 network nanoparticles prepared by the above method as a catalyst, the OER reaction (oxygen evolution reaction) performance test was carried out on the bimetallic doped nanoparticles prepared in Example 1. The specific experimental scheme is as follows:

[0063] 5 mg of Ni3Se4 nanoparticles were weighed as a catalyst sample and added to a solution containing 485 μL of isopropanol and 15 μL of Naifon solution (5 wt%). The sample was then sonicated for 30 minutes to uniformly disperse the catalyst. 5 μL of the uniformly dispersed sample solution was applied to a glassy carbon electrode. After drying, the test was performed using a standard three-electrode system with a graphite rod as the counter electrode, mercury / mercuric oxide as the reference electrode, and 1 M KOH as the electrolyte. The linear voltammetric curve was obtained at a scan rate of 5 mV / s.

[0064] Test results: Figure 5 As shown, when obtaining The overpotential is 227 mV at a current density of 1.5 Å. The OER catalyst is more active than commercial IrO2 and most reported OER catalysts.

[0065] Example 2

[0066] Step 1: Take 1.2 mmol of red phosphorus and add 0.1 mL of deionized water in batches for grinding to obtain the first turbid solution;

[0067] Step 2: Weigh 1.2 mmol of selenium powder (Se), 0.4 mmol of nickel nitrate hexahydrate (Ni(NO3)2•6H2O), 0.4 mmol of ferric chloride hexahydrate (FeCl3•6H2O), and 2 mmol of urea into a beaker. First, add the first turbid solution, then add 30 mL of deionized water, stir vigorously for 10 minutes, and mix well to obtain a second turbid solution.

[0068] Step 3: Transfer the second turbid liquid to a high-pressure reactor, heat the second turbid liquid to 150° C., keep the temperature for 10 hours, and then cool it to obtain a preliminary product;

[0069] Step 4: The preliminary product was washed with water and ethanol, and then vacuum dried at 55°C to finally obtain P and Fe co-doped Ni3Se4 network nanoparticles.

[0070] The P and Fe co-doped Ni3Se4 nanoparticles prepared in Example 2 were subjected to an OER reaction (oxygen evolution reaction) performance test, and the specific implementation method was the same as the OER reaction (oxygen evolution reaction) performance test performed in Example 1 above.

[0071] Test results: Figure 6 As shown, when obtaining At a current density of , the overpotential is 245 mV.

[0072] Example 3

[0073] Step 1: Take 2.4 mmol of red phosphorus and add 0.25 mL of deionized water in batches for grinding to obtain the first turbid solution;

[0074] Step 2: Weigh 1.2 mmol of selenium powder (Se), 0.3 mmol of nickel nitrate hexahydrate (Ni(NO3)2•6H2O), 0.3 mmol of ferric chloride hexahydrate (FeCl3•6H2O), and 4 mmol of urea into a beaker. First, add the first turbid solution, then add 30 mL of deionized water, stir vigorously for 35 minutes, and mix well to obtain a second turbid solution.

[0075] Step 3: Transfer the second turbid liquid to a high-pressure reactor, heat the second turbid liquid to 180° C., keep the temperature for 16 hours, and then cool it to obtain a preliminary product;

[0076] Step 4: The preliminary product was washed with water and ethanol, and then vacuum dried at 62°C to finally obtain P and Fe co-doped Ni3Se4 network nanoparticles.

[0077] The P and Fe co-doped Ni3Se4 nanoparticles prepared in Example 3 were subjected to an OER reaction (oxygen evolution reaction) performance test, and the specific implementation method was the same as the OER reaction (oxygen evolution reaction) performance test performed in Example 1 above.

[0078] Test results: Figure 7 As shown, when obtaining At a current density of , the overpotential is 233 mV.

[0079] Example 4

[0080] Step 1: Take 3.6 mmol of red phosphorus and add 0.4 mL of deionized water in batches for grinding to obtain the first turbid solution;

[0081] Step 2: Weigh 1.2 mmol of selenium powder (Se), 0.2 mmol of nickel nitrate hexahydrate (Ni(NO3)2•6H2O), 0.6 mmol of ferric chloride hexahydrate (FeCl3•6H2O), and 3 mmol of urea into a beaker. First, add the first turbid solution, then add 34 mL of deionized water, stir vigorously for 60 minutes, and mix thoroughly to obtain a second turbid solution.

[0082] Step 3: Transfer the second turbid liquid to a high-pressure reactor, heat the second turbid liquid to 220° C., keep the temperature for 20 hours, and then cool it to obtain a preliminary product;

[0083] Step 4: The preliminary product was washed with water and ethanol, and then vacuum dried at 65°C to finally obtain P and Fe co-doped Ni3Se4 network nanoparticles.

[0084] The P and Fe co-doped Ni3Se4 nanoparticles prepared in Example 4 were subjected to an OER reaction (oxygen evolution reaction) performance test, and the specific implementation method was the same as the OER reaction (oxygen evolution reaction) performance test performed in Example 1 above.

[0085] Test results: Figure 8 As shown, when obtaining At a current density of , the overpotential is 257 mV.

[0086] In addition, in order to further illustrate the technical aspects of the present invention, the following comparative examples are provided. The implementation steps of the following comparative examples are substantially the same as those of the preparation method of the present invention, and are specifically as follows:

[0087] Comparative Example 1

[0088] 3.6 mmol of selenium powder (Se), 0.45 mmol of nickel nitrate hexahydrate (Ni(NO3)2•6H2O), 0.15 mmol of ferric chloride hexahydrate (FeCl3•6H2O) and 8.3 mmol of urea were weighed into a beaker, 30 mL of deionized water was added, and the mixture was vigorously stirred for 30 min. After mixing evenly, the mixture was transferred to a reactor, heated to 200°C, and kept warm for 14 h. After cooling, the mixture was collected and washed, and then vacuum dried to obtain a phosphorus-free mixture of Fe-doped NiSe2 and Se.

[0089] The only difference between Comparative Example 1 and Example 1 is that Example 1 adds red phosphorus, while Comparative Example 1 does not add red phosphorus.

[0090] like Figure 9 As shown, the sample prepared in Comparative Example 1 was characterized by XRD. As can be seen from the figure, the diffraction peaks of the obtained sample are consistent with those of the standard cards of NiSe2 and Se, indicating that the selenium powder in Comparative Example 1 cannot react completely without adding red phosphorus.

[0091] like Figure 10 As shown, the sample prepared in Comparative Example 1 was characterized by SEM. The SEM image shows that the obtained sample consists of multifaceted prisms and nanoparticles distributed thereon. It can also be clearly seen from the SEM image that the phase of the selenide synthesized without the addition of red phosphorus is uneven, and the reaction system cannot fully react without the addition of red phosphorus.

[0092] The mixture of Fe-doped NiSe2 and Se prepared in Comparative Example 1 was subjected to an OER reaction (oxygen evolution reaction) performance test, and the specific implementation method was the same as the OER reaction (oxygen evolution reaction) performance test performed in Example 1 above.

[0093] Test results: Figure 11 As shown, when obtaining At a current density of , the overpotential is 351 mV.

[0094] Comparative Example 2

[0095] First, 2.4 mmol of red phosphorus (RP) was added to 0.5 mL of deionized water in batches, and the first turbid liquid was obtained after grinding; then, 1.2 mmol of selenium powder (Se), 0.6 mmol of nickel nitrate hexahydrate (Ni(NO3)2•6H2O) and 8.3 mmol of urea (urea) were weighed into a beaker and the first turbid liquid was added; secondly, 29.5 mL of deionized water was added, and the mixture was stirred vigorously for 30 minutes. After mixing evenly, the mixture was transferred to a reactor, heated to 200°C, and kept warm for 14 hours; after cooling, the mixture was collected and washed, and then vacuum dried to obtain a P-doped Ni3Se4 catalyst.

[0096] The only difference between Comparative Example 2 and Example 1 is that no iron salt is added during the synthesis process of Comparative Example 2.

[0097] The P-doped Ni3Se4 prepared in Comparative Example 2 was subjected to an OER reaction (oxygen evolution reaction) performance test, and the specific implementation method was the same as the OER reaction (oxygen evolution reaction) performance test performed in the above Comparative Example 1.

[0098] Test results: Figure 12 As shown, when obtaining At a current density of 1.5 Å, the overpotential is 268 mV. This overpotential is significantly higher than that of the Fe-doped catalyst, indicating that Fe-doping can optimize the adsorption capacity of oxygen-containing intermediates, enhance its conductivity, and improve the intrinsic activity of the catalyst.

[0099] Comparative Example 3

[0100] First, 3.6 mmol of selenium powder (Se), 0.6 mmol of nickel nitrate hexahydrate (Ni(NO3)2•6H2O) and 8.3 mmol of urea were weighed into a beaker, 30 mL of deionized water was added, and the mixture was vigorously stirred for 30 min. After mixing evenly, the mixture was transferred to a reactor, heated to 200°C, and kept warm for 14 h. After cooling, the mixture was collected and washed, and then vacuum dried to obtain a mixture of NiSe2 and Se that was free of phosphorus and iron.

[0101] The only difference between Comparative Example 3 and Example 1 is that only nickel salt and selenium powder are added, and no P and Fe ions are added.

[0102] The mixture of NiSe2 and Se prepared in Comparative Example 3 was subjected to an OER reaction (oxygen evolution reaction) performance test, and the specific implementation method was the same as the OER reaction (oxygen evolution reaction) performance test performed in the above Comparative Example 1.

[0103] Test results: Figure 13 As shown, when obtaining At a current density of 1.5 Å, the overpotential is 402 mV. The OER activity of NiSe2 / Se is significantly lower than that of other control samples, indicating that the incorporation of P and Fe is crucial for improving catalyst performance. The addition of red phosphorus not only promotes the selenization reaction but also acts as an anionic dopant, working together with the cationic "Fe" dopant to modulate the catalyst's electronic structure and enhance its intrinsic activity.

[0104] The present invention selects naturally abundant transition metal elements Ni and Fe as well as stable red phosphorus and selenium powder as raw materials, and carries out a one-step hydrothermal reaction in a urea aqueous solution to prepare an electrolytic water oxygen evolution catalyst with excellent performance. The synthesis method is simple and convenient, can achieve maximum economic benefits, and is conducive to subsequent industrial-scale application.

[0105] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for preparing P and Fe co-doped Ni3Se4 nanomaterials, characterized in that: The specific steps include: Step 1: Grind red phosphorus with water to obtain a first turbid solution; Step 2: Add appropriate amounts of selenium powder, nickel salt, iron salt, and urea to the first turbid liquid, stir vigorously, and add water to mix evenly to obtain a second turbid liquid; Step 3: heating the second turbid liquid, keeping it warm for a certain period of time, and then cooling it to obtain a preliminary product; Step 4: The preliminary product is washed and then vacuum dried to finally obtain P and Fe co-doped Ni3Se4 network nanoparticles.

2. The method for preparing a P and Fe co-doped Ni3Se4 nanomaterial according to claim 1, characterized in that: Calculated by the amount of substance, the amount of red phosphorus used in step 1 is 2-4 mmol; the water is deionized water, and the amount of water used in step 1 is 0.1-0.5 mL.

3. The method for preparing a P and Fe co-doped Ni3Se4 nanomaterial according to claim 1, characterized in that: In the step 2, the ratio of the nickel salt to the iron salt is 1-3:3-1.

4. The method for preparing a P and Fe co-doped Ni3Se4 nanomaterial according to claim 1, characterized in that: In step 2, the concentration of the nickel salt is 1-3 mM, and the concentration of the urea is 5-10 mM.

5. The method for preparing a P and Fe co-doped Ni3Se4 nanomaterial according to claim 1, characterized in that: In step 2, the nickel salt is nickel nitrate hexahydrate, and the iron salt is ferric chloride hexahydrate.

6. The method for preparing a P and Fe co-doped Ni3Se4 nanomaterial according to claim 1, characterized in that: Calculated by the amount of substance, the ratio of the amount of selenium powder used in step 2 to the amount of red phosphorus used in step 1 is 1:1-2.

7. The method for preparing a P and Fe co-doped Ni3Se4 nanomaterial according to claim 1, characterized in that: In step 2, after adding selenium powder, nickel salt, iron salt and urea to the first turbid solution, the stirring time is 10-60 minutes.

8. The method for preparing a P and Fe co-doped Ni3Se4 nanomaterial according to claim 1, characterized in that: The specific process of step 4 is: washing the preliminary product with water and ethanol in sequence, and then vacuum drying it in an environment of 55-65° C. to obtain P and Fe co-doped Ni 3 Se 4 nanomaterials.

9. A P and Fe co-doped Ni3Se4 nanomaterial, characterized in that: The Ni3Se4 nanomaterial is obtained by the preparation method of a P and Fe co-doped Ni3Se4 nanomaterial as described in any one of claims 1 to 8, and has a network-like nanoparticle morphology.

10. Use of the P and Fe co-doped Ni3Se4 nanomaterial according to claim 9 as an electrocatalyst for oxygen evolution reaction.

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