A preparation method of a high-entropy phosphorus-fluoride nanoparticle catalyst, the prepared catalyst and an oxygen evolution electrode

Abstract

The application belongs to the technical field of water electrolysis catalysis, and particularly relates to a preparation method of high-entropy phosphorus-fluoride nanoparticle catalyst, the prepared catalyst and an oxygen evolution electrode. The preparation steps of the high-entropy phosphorus-fluoride nanoparticle catalyst provided by the application are as follows: firstly, soluble metal salts of Ni, Fe, Cu, Co and Mn are dissolved in distilled water or / and ethanol to configure a metal salt solution with a concentration of 0.005 mol / L, the solution is atomized into micro-nano-sized aerosol droplets and blown into an ammonium hydroxide solution, after atomization, suction filtration and drying, a precursor powder is obtained; then the precursor powder is reacted with PH3 and HF respectively in an oxygen-free environment, and after the reaction is completed, the high-entropy phosphorus-fluoride nanoparticle catalyst is obtained. The preparation method can synthesize the precursor at normal temperature and pressure, and the temperature for preparing the high-entropy phosphorus-fluoride nanoparticle catalyst is only 500 DEG C, which is obviously lower than that of the traditional high-entropy alloy melting and forging preparation technology.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of water electrolysis catalysts, and particularly relates to a preparation method of a high-entropy phosphorus-fluoride nanoparticle catalyst, and also relates to a prepared catalyst and an oxygen evolution electrode using the catalyst. BACKGROUND

[0002] In recent years, catalysts based on high-entropy materials (HEMs) have been widely used to reduce the energy consumption of the oxygen evolution reaction (OER). High-entropy materials (HEMs) were defined in the earliest research as a new type of material composed of five or more elements with atomic ratios of 5-35% in a single crystal form. This qualitative description of HEMs, although direct and useful, lacks clear boundary conditions, so later people defined materials with a configurational entropy greater than or equal to 1.5 R as high-entropy systems. HEMs have four "core effects", including the thermodynamic high-entropy effect, the structural lattice distortion effect, the kinetic sluggish diffusion effect and the performance "cocktail" effect, which make them have potential application value in many fields. Among them, the high-entropy effect refers to the high configurational entropy of HEMs, which makes materials containing five or more near / equal molar ratio of metal element types more inclined to form single-phase solid solutions (rather than intermetallic compounds). The sluggish diffusion effect refers to the fact that due to the high diffusion energy barrier, the diffusion and phase transition of atoms inside HEMs are very slow, unlike the uniform diffusion of traditional alloys. These two effects endow HEMs with excellent electrochemical stability and corrosion resistance, making them a focus of researchers in the field of water electrolysis catalysts.

[0003] In order to significantly improve the electrocatalytic performance, the design of electrocatalysts mainly focuses on increasing the number of active sites, changing the coordination environment and improving the electronic structure, etc. Therefore, the design strategy of advanced multi-principal element metal-based catalysts not only focuses on the design of components, but also emphasizes the control of morphology. It is well known that catalysts must be in direct contact with reactants to exert their catalytic effect, and nanomaterials have outstanding advantages in this regard. For HEMs, when they are reduced to nanoscale, the large surface area, high potential energy, obvious lattice distortion and significant synergistic effect make nanoscale HEMs ideal catalysts for OER.

[0004] To obtain nanosized HEMs, people have explored biomass template method, MOFs template method, non-template method and other methods, wherein in the non-template method, due to the wet chemical method, its precision in controlling size, morphology and composition shows special prospects. However, a challenge still exists: most synthetic compounds only contain three or fewer elements. This limitation stems from the apparent immiscibility in the synthesis process. Although the high-entropy effect can promote the formation of a homogeneous phase, to achieve the optimal mixing entropy, there needs to be strict conditions, such as increasing the heating temperature. Therefore, there is an urgent need for a method that can synthesize HEMs under mild conditions. SUMMARY

[0005] In view of the problems and deficiencies in the prior art, the purpose of the present application is to provide a preparation method of high-entropy phosphorus-fluoride nanoparticle catalyst, and also provide the prepared catalyst and an oxygen evolution electrode using the catalyst.

[0006] Based on the above purpose, the technical scheme adopted by the present application is as follows:

[0007] The present application provides a preparation method of high-entropy phosphorus-fluoride nanoparticle catalyst, comprising the following steps:

[0008] S1: Dissolve soluble metal salts of Ni, Fe, Cu, Co and Mn in distilled water or / and ethanol to prepare a metal salt solution with a concentration of 0.001-0.1 mol / L, and ultrasonic treatment to mix the solution uniformly; atomize the solution into micro-nano-sized aerosol droplets and blow them into an ammonium hydroxide solution, after atomization, filter and dry to obtain a precursor powder;

[0009] S2: React the precursor powder with PH3 and HF respectively in an oxygen-free environment to obtain (FeCoNiCuMn)P2 / (FeCoNiCuMn)F2 heteronanoparticles, and then wash with water to obtain the high-entropy phosphorus-fluoride nanoparticle catalyst.

[0010] Further, the size of the aerosol droplets is 2-4 μm.

[0011] Further, the soluble metal salt of Ni, Fe, Cu, Co, and Mn can be any one of nitrate, sulfate, chloride, and acetate. When preparing the solution of the soluble metal salt of Ni, Fe, Cu, Co, and Mn, the solvent can be distilled water, anhydrous ethanol, or an ethanol solution. When the solvent is distilled water, the reaction speed of the aerosol droplets of the metal salt solution with the ammonium hydroxide solution is fast, the generated precursor powder has a large particle size, and the particle size of the precursor powder ranges from several hundred nanometers to tens of microns. When the solvent is ethanol, the reaction speed of the aerosol droplets of the metal salt solution with the ammonium hydroxide solution is slow, the generated precursor powder has a small particle size, and the particle size of the precursor powder ranges from tens of nanometers to several hundred nanometers. To better control the particle size of the precursor powder, the solvent is preferably anhydrous ethanol.

[0012] Further, when the aerosol droplets are blown into the ammonium hydroxide solution for reaction, the aerosol generated by atomization can be continuously sprayed onto the interface of the ammonium hydroxide solution, or the pipeline conveying the aerosol can be introduced into the ammonium hydroxide solution for reaction. This process is relatively slow, the volume ratio of the metal salt solution to the ammonium hydroxide solution before atomization is about 1:1, it takes 10-16 hours to completely atomize the metal salt solution with the same volume, and the reaction can be completed after atomization and blowing, followed by filtration, drying, and other operations.

[0013] Further, the specific process of the reaction of the precursor powder with PH3 in step S2 is as follows: NaH2PO2 is placed upstream of the reactor, the precursor powder is spread downstream of the reactor, inert gas is introduced from upstream to downstream, and the reactor is heated to make NaH2PO2 thermally decompose, and the PH3 generated by thermal decomposition is carried to the downstream by nitrogen or inert gas to react with the precursor powder. NaH2PO2 should not be in contact with the precursor powder, and preferably a certain distance (3-5 cm) is maintained to prevent the product from being contaminated by the residues of NaH2PO2 after thermal decomposition.

[0014] Further, the temperature of the phosphorization reaction is 250-550°C.

[0015] Further, the specific process of the reaction of the precursor powder with HF in step S2 is as follows: NH4F is placed upstream of the reactor, the precursor powder is spread downstream of the reactor, inert gas is introduced from upstream to downstream, and the reactor is heated to make NH4F thermally decompose, and the HF generated by thermal decomposition is carried to the downstream by nitrogen or inert gas to react with the precursor powder.

[0016] Further, the temperature of the fluorination reaction is 300-700°C.

[0017] Further, the inert gas is Ar gas, the Ar gas flow rate during phosphorization and fluorination is 50 ml / min; the phosphorization is performed first and then fluorination, NaH2PO2 and NH4F are supplied in excess, the phosphorization time is 2-3 h, and the fluorination time is 5-30 min. The sufficient supply of phosphorus source and the phosphorization time of 2-3 h can ensure that the phosphorization reaction is fully carried out; and then the amount of phosphide converted into fluoride is controlled by controlling the fluorination time, so as to control the proportion of (FeCoNiCuMn)P2 and (FeCoNiCuMn)F2 components in the product.

[0018] Further, since the atomization and blowing process of the metal salt solution needs a long time, and the ammonia in the ammonium hydroxide solution is extremely volatile, the ammonium hydroxide solution selects ammonia water with ammonia concentration ≥20wt%.

[0019] The application further provides a high-entropy phosphorus-fluoride nanoparticle catalyst prepared by the preparation method.

[0020] The application further provides an oxygen evolution electrode prepared by using the high-entropy phosphorus-fluoride nanoparticle catalyst.

[0021] Further, the preparation steps of the electrode are as follows:

[0022] The carbon rod (CR, diameter 5 mm, length 100 mm) is immersed in a 1.0 M H2SO4 solution for 1 h to remove impurities, and then immersed in anhydrous ethanol for 3 h to improve hydrophilicity; then 0.03 g of the high-entropy phosphorus-fluoride nanoparticle catalyst sample powder is dispersed in a mixture of 490 μL of anhydrous ethanol, 490 μL of deionized water and 20 μL of Nafion dispersion solution; then 20 μL of the slurry is uniformly coated on the surface of the pretreated carbon rod, and the electrode is obtained after drying at room temperature for 24 h.

[0023] Compared with the prior art, the application has the following beneficial effects:

[0024] (1) Since the deposition thermodynamics of different ions are different, the preparation of HEMs catalysts often encounters challenges. The uniform distribution of multiple elements in nanoparticles (NPs) requires high temperature (usually more than 1000℃), complicated procedures and special equipment. The method of the application first encapsulates Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ and Mn 2+ ions in ethanol droplets, when these droplets carrying ions are blown into the ammonium hydroxide solution, a large amount of OH -Ions encapsulated and separated these microdroplets. Subsequently, these OH groups... - Ions react with different metal ions to form precursors. In this microdroplet environment, metal ions are continuously exposed to OH-. - In the presence of ions, this facilitates their rapid conversion into hydroxides (NPs). This invention effectively mitigates the challenges posed by the different thermodynamics of reactions involving different ions. By confining the reaction within microdroplets, the elemental proportions in the precursor are closely matched to those in the initial solution.

[0025] (2) Furthermore, the separation of each droplet by the ammonium hydroxide solution restricts ion diffusion and prevents unnecessary volume accumulation. Therefore, a uniform, ink-like suspension can be obtained. The resulting precursor exhibits a flocculent microstructure, keeping it suspended in the droplets. After phosphating and fluorination, the hydroxide flocculents transform into heterogeneous nanoparticles. The in-situ and localized transformation process ensures that the obtained (FeCoNiCuMn)P2 / (FeCoNiCuMn)F2 (FeCoNiCuMn high-entropy phosphorus-fluoride) composite material has a good microscopic contact interface between its (FeCoNiCuMn)P2 and (FeCoNiCuMn)F2 components. If the ammonium hydroxide solution is replaced with other strongly alkaline solutions (e.g., NaOH solution), it is found that the droplets are broken down, resulting in a blocky morphology, which may be due to the faster reaction rate.

[0026] (3) It is worth noting that the precursor is synthesized at room temperature and pressure. The preparation temperature of the (FeCoNiCuMn)P2 / (FeCoNiCuMn)F2 composite material is only 300-700℃, which is significantly lower than the traditional HEMs preparation technology. Attached Figure Description

[0027] Figure 1 A schematic diagram of the synthesis and preparation process of FeCoNiCuMn high-entropy phosphorus-fluoride catalyst;

[0028] Figure 2 The results of OER catalytic performance, electrochemical impedance spectroscopy, and response current stability tests of the samples from Example 1, Comparative Example 1, and Comparative Example 2 are as follows:

[0029] Figure 3 Figures showing the structural and component characterization results of different samples;

[0030] Figure 4 The test results of OER catalytic performance and electrochemical impedance of samples obtained at different fluorination times;

[0031] Figure 5 The test results show the OER catalytic performance and electrochemical impedance of samples with different elemental compositions. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0033] (I) Discussion on phosphating and fluorination reactions in the preparation methods of high-entropy phosphorus-fluoride nanoparticle catalysts

[0034] Example 1

[0035] A method for preparing a high-entropy phosphorus-fluoride nanoparticle catalyst, such as... Figure 1 As shown, it includes the following steps:

[0036] S1: Precursor preparation using a droplet-particle method: Five metal salts, namely Ni(NO3)2, Fe(NO3)3, Cu(NO3)2, Co(NO3)2, and Mn(NO3)2, were dissolved in anhydrous ethanol to prepare equimolar concentration (0.005 mol / L) metal salt solutions. The solutions were then sonicated for 30 min to ensure homogeneity. The solutions were then atomized using an Owegels medical nebulizer to generate micro / nano-sized (approximately 2 μm) aerosol droplets. These metal ion-containing aerosol droplets were blown into an ammonium hydroxide solution using air. Each droplet acted as a microreactor, reacting with OH... - The aerosol droplets are surrounded and complexed. After atomization, the ammonium hydroxide solution used to collect the aerosol droplets is filtered. The precipitate obtained by filtration is placed in a vacuum oven and dried at 30°C to obtain the precursor powder.

[0037] S2: The precursor powder is reacted with PH3 and HF in an oxygen-free environment to perform phosphating and fluorination treatments, respectively.

[0038] (1) Phosphating treatment: about 1.0 g NaH2PO2 was placed in the upstream of the quartz tube furnace, and 0.5 g precursor powder was spread in the downstream of the quartz tube furnace. The two were kept out of contact. Ar gas was introduced from upstream to downstream, and the quartz tube furnace was heated to thermally decompose NaH2PO2. The PH3 produced by the thermal decomposition of NaH2PO2 was carried downstream by Ar gas to react with the precursor powder in the phosphating reaction. The phosphating reaction temperature was 350℃ and the reaction time was 2 h. After the phosphating reaction was completed, (FeCoNiCuMn)P2 material was obtained.

[0039] (2) Fluorination treatment: 1.0 g of NH4F was placed in the upstream of a quartz tube furnace, and the (FeCoNiCuMn)P2 material obtained by phosphating was spread in the downstream of the quartz tube furnace. Ar gas was introduced from upstream to downstream, and the quartz tube furnace was heated to thermally decompose NH4F. The HF produced by the thermal decomposition of NH4F was carried downstream by Ar gas to react with the (FeCoNiCuMn)P2 material in a fluorination reaction. The fluorination reaction temperature was 500℃ and the reaction time was 15 min. After the fluorination reaction was completed, the (FeCoNiCuMn)P2 / (FeCoNiCuMn)F2 heterogeneous nanoparticle catalyst was obtained.

[0040] Comparative Example 1

[0041] A method for preparing a high-entropy phosphide nanoparticle catalyst includes the following steps:

[0042] S1: Precursor preparation using a droplet-particle method: Five metal salts, namely Ni(NO3)2, Fe(NO3)3, Cu(NO3)2, Co(NO3)2, and Mn(NO3)2, were dissolved in anhydrous ethanol to prepare equimolar concentration (0.005 mol / L) metal salt solutions. The solutions were then sonicated for 30 min to ensure homogeneity. The solutions were then atomized using an Owegels medical nebulizer to generate micro / nano-sized (approximately 2 μm) aerosol droplets. These metal ion-containing aerosol droplets were blown into an ammonium hydroxide solution using air. Each droplet acted as a microreactor, reacting with OH... - The aerosol droplets are surrounded and complexed. After atomization, the ammonium hydroxide solution used to collect the aerosol droplets is filtered. The precipitate obtained by filtration is placed in a vacuum oven and dried at 30°C to obtain the precursor powder.

[0043] S2: Phosphating treatment: Approximately 1.0 g of NaH2PO2 was placed upstream in a quartz tube furnace, and 0.5 g of precursor powder was spread downstream in the same furnace, avoiding contact between the two. Ar gas was introduced from upstream to downstream while the quartz tube furnace was heated to thermally decompose NaH2PO2. The PH3 produced by the thermal decomposition of NaH2PO2 was carried downstream by the Ar gas to react with the precursor powder in a phosphating reaction. The phosphating reaction temperature was 350℃ and the reaction time was 2 h. After the phosphating reaction was completed, (FeCoNiCuMn)P2 material was obtained. The product was washed with distilled water to obtain FeCoNiCuMn high-entropy phosphide nanoparticle catalyst.

[0044] Comparative Example 2

[0045] A method for preparing a high-entropy fluoride nanoparticle catalyst includes the following steps:

[0046] S1: Precursor preparation using a droplet-particle method: Five metal salts, namely Ni(NO3)2, Fe(NO3)3, Cu(NO3)2, Co(NO3)2, and Mn(NO3)2, were dissolved in anhydrous ethanol to prepare equimolar concentration (0.005 mol / L) metal salt solutions. The solutions were then sonicated for 30 min to ensure homogeneity. The solutions were then atomized using an Owegels medical nebulizer to generate micro / nano-sized (approximately 2 μm) aerosol droplets. These metal ion-containing aerosol droplets were blown into an ammonium hydroxide solution using air. Each droplet acted as a microreactor, reacting with OH... - The aerosol droplets are surrounded and complexed. After atomization, the ammonium hydroxide solution used to collect the aerosol droplets is filtered. The precipitate obtained by filtration is placed in a vacuum oven and dried at 30°C to obtain the precursor powder.

[0047] S2: Fluorination treatment: Approximately 1.0 g of NH4F was placed upstream in a quartz tube furnace, and 0.5 g of precursor powder was spread downstream in the same furnace. Ar gas was introduced from upstream to downstream while the furnace was heated to thermally decompose NH4F. The HF produced by the thermal decomposition of NH4F was carried downstream by the Ar gas to react with the precursor powder in a fluorination reaction. The fluorination reaction temperature was 500℃ and the reaction time was 15 min. After the fluorination reaction was completed, (FeCoNiCuMn)F2 material was obtained. After rinsing with distilled water, FeCoNiCuMn high-entropy fluoride nanoparticle catalyst was obtained.

[0048] The samples from Example 1, Comparative Example 1, and Comparative Example 2 were prepared as oxygen evolution electrodes to evaluate the OER catalytic performance of the high-entropy catalyst. Compared with FeCoNiCuMn high-entropy fluoride and FeCoNiCuMn high-entropy phosphide, the optimized FeCoNiCuMn high-entropy phosphorus-fluoride electrode exhibited better catalytic activity, requiring only 209 mV@10 mA cm⁻¹ in alkaline solution. -2 and 346mV@100 mA cm -2 ( Figure 2 a).

[0049] Furthermore, the charge transfer resistances of FeCoNiCuMn high-entropy phosphorus-fluoride, FeCoNiCuMn high-entropy fluoride, and FeCoNiCuMn high-entropy phosphorus are 1.7 Ω, 7.4 Ω, and 3.7 Ω, respectively. Figure 2 b). This indicates that the FeCoNiCuMn high-entropy phosphorus-fluoride catalyst exhibits a higher charge transfer rate, faster reaction kinetics, and better electrocatalytic performance for the oxygen evolution reaction. The FeCoNiCuMn high-entropy phosphorus-fluoride catalyst demonstrates good stability; in the first ten hours of testing, due to the activation reaction (increased transition metal valence state), the corresponding electrode current increases ( Figure 2 c).

[0050] Furthermore, the samples prepared in Example 1, Comparative Example 1, and Comparative Example 2 were subjected to structural and component characterization analysis, and the results are as follows: Figure 3 As shown, the catalyst precursor exhibits a spherical structure, primarily composed of water and metal hydroxides. Figure 3 (a, 3b). From Figure 3 c's HEP and Figure 3 The XRD patterns of HEF and HEPF show that the crystal structure of high-entropy phosphide is similar to that of the CoP2 phase (JCPDS 77-0263), but slightly shifted to the right, indicating a smaller lattice spacing. Conversely, the crystal structure of high-entropy fluoride is similar to that of the CoF2 phase (JCPDS 77-0653), with characteristic peaks shifted to the left, indicating a larger lattice spacing. Furthermore, the crystal structure of high-entropy phosphorus-fluoride mainly reflects the high-entropy fluoride phase, while the high-entropy phosphide peaks are obscured, possibly due to the coating of the high-entropy fluoride. The morphologies of FeCoNiCuMn high-entropy phosphorus-fluoride, FeCoNiCuMn high-entropy fluoride, and FeCoNiCuMn high-entropy phosphide catalysts are shown in the figures. Figure 3 As shown in (e.g.), all catalysts exhibit porous nanoparticle structures, exposing abundant catalytic active sites and a large specific surface area, which is beneficial for enhancing ion diffusion and mass transfer during the reaction. Figure 3 The EDS spectrum in h shows that the metal elements (Fe, Co, Ni, Cu and Mn) and non-metal elements (P, F, N and O) in HEPF are uniformly distributed, with no obvious elemental segregation. Combined with XRD, it is confirmed that a high-entropy material has been obtained.

[0051] (II) Discussion on fluorination time in the preparation method of high-entropy phosphorus-fluoride nanoparticle catalysts

[0052] Example 2

[0053] The preparation method of a high-entropy phosphorus-fluoride nanoparticle catalyst is basically the same as that in Example 1, except that the fluorination time is 5 min.

[0054] Example 3

[0055] The preparation method of a high-entropy phosphorus-fluoride nanoparticle catalyst is basically the same as that in Example 1, except that the fluorination time is 30 min.

[0056] Example 4

[0057] The preparation method of a high-entropy phosphorus-fluoride nanoparticle catalyst is basically the same as that in Example 1, except that the fluorination time is 120 min.

[0058] The molar ratio of high-entropy phosphide to high-entropy fluoride in the catalyst samples prepared in Examples 1-4 was tested, and the results are shown in Table 1.

[0059] Table 1. Molar ratio of phosphide to fluoride in high-entropy phosphorus-fluoride compounds

[0060]

[0061] This invention synthesizes a high-entropy phosphorus-fluoride nanoparticle catalyst composite material using a method of phosphating followed by fluorination. It was found that the molar ratio of high-entropy phosphide to high-entropy fluoride in the composite material is highly dependent on the fluorination time. As shown in Table 1, the F:P molar ratio increases with increasing fluorination time, indicating the formation of more high-entropy fluoride.

[0062] Furthermore, the samples from Examples 1-4 were prepared as electrodes, and the catalytic activity and electrochemical resistance of the corresponding electrode materials obtained at different fluorination times were investigated and analyzed. The experimental methods are as follows:

[0063] An electrochemical workstation (CHI 760E) was used with a three-electrode system. The prepared electrode, carbon rod electrode, and Ag / AgCl electrode were used as the working electrode, counter electrode, and reference electrode, respectively, to test the electrochemical performance of the catalyst. All electrochemical experiments were conducted in an electrolytic cell containing 1.0 M KOH. The catalytic activity for water electrolysis was determined using linear sweep voltammetry (LSV, scan rate 2 mV s⁻¹). The OER kinetics of the catalyst were characterized using electrochemical impedance spectroscopy (EIS). Ohmic resistance (Rs) was obtained from the high-frequency region, and charge transfer resistance (Rct) was simulated from the radius of the arc on the Nyquist plot. Electrochemical impedance spectroscopy analysis was performed in the frequency range of 0.05 Hz to 0.1 MHz, and the results are as follows: Figure 4 As shown.

[0064] Depend on Figure 4 It can be seen that the high-entropy phosphorus-fluoride nanoparticle catalyst composite material prepared with a fluorination time of 15 min has the highest catalytic activity and the lowest electrochemical resistance.

[0065] (III) Discussion on the type and quantity of metal ions in the preparation method of high-entropy phosphorus-fluoride nanoparticle catalysts

[0066] Comparative Example 3

[0067] The preparation method of a medium-entropy phosphorus-fluoride nanoparticle catalyst is basically the same as that in Example 1, except that the metal salt is one of three types: Ni(NO3)2, Fe(NO3)3, and Co(NO3)2. The FeCoNi medium-entropy phosphorus-fluoride is prepared by this method.

[0068] Comparative Example 4

[0069] The preparation method of a medium-entropy phosphorus-fluoride nanoparticle catalyst is basically the same as that in Example 1, except that the metal salt is one of four types: Ni(NO3)2, Fe(NO3)3, Cu(NO3)2, and Co(NO3)2. The FeCoNiCu medium-entropy phosphorus-fluoride is prepared by this method.

[0070] Comparative Example 5

[0071] The preparation method of a high-entropy phosphorus-fluoride nanoparticle catalyst is basically the same as that in Example 1, except that the metal salt is one of five types: Ni(NO3)2, Fe(NO3)3, Cu(NO3)2, Co(NO3)2, and Y(NO3)3. The FeCoNiCuY high-entropy phosphorus-fluoride is prepared by this method.

[0072] Comparative Example 6

[0073] The preparation method of a high-entropy phosphorus-fluoride nanoparticle catalyst is basically the same as that in Example 1, except that the metal salts are Ni(NO3)2, Fe(NO3)3, Cu(NO3)2, Co(NO3)2, Y(NO3)3, Mn(NO3)2, Al(NO3)3, Mg(NO3)2, Ca(NO3)2, and La(NO3)2, ten kinds in total. The high-entropy phosphorus-fluoride FeCoNiCuMnYAlMgCaLa is prepared by this method.

[0074] The samples from Example 1 and Comparative Examples 3-6 were prepared as electrodes. The catalytic activity and electrochemical resistance of the corresponding electrode materials obtained under different element types and amounts in the catalyst were investigated and analyzed. The results are as follows: Figure 5 As shown:

[0075] like Figure 5 As shown, the effect of different element types and quantities on the performance of electrocatalysts is illustrated. Catalytic activity is not linearly correlated with entropy increase (element types); element type plays a more crucial role in determining catalytic activity. When the number of element types increases from 3 to 5, the catalyst's response current density increases significantly, as shown in the figure. Figure 5As shown in a. The OER catalytic activities of medium-entropy phosphide-fluorides and high-entropy phosphide-fluorides are in the order: FeCoNi medium-entropy phosphide-fluoride < FeCoNiCu medium-entropy phosphide-fluoride < FeCoNiCuMnYAlMgCaLa high-entropy phosphide-fluoride < FeCoNiCuY high-entropy phosphide-fluoride < FeCoNiCuMn high-entropy phosphide-fluoride. Electrochemical impedance spectroscopy (EIS) further shows that the charge transfer resistance (Rct) of FeCoNiCuMn high-entropy phosphide-fluoride is significantly reduced compared with other medium-entropy phosphide-fluorides or high-entropy phosphide-fluorides (as Figure 5 b).

Claims

1. A method for preparing a high-entropy phosphorus-fluoride nanoparticle catalyst, characterized in that, Includes the following steps: S1: Dissolve soluble metal salts of Ni, Fe, Cu, Co, and Mn in anhydrous ethanol to prepare a metal salt solution with a concentration of 0.001-0.1 mol / L. Sonicate the solution to make it homogeneous. Atomize the solution into micro-nano aerosol droplets and blow them into an ammonium hydroxide solution. After atomization, filter and dry to obtain precursor powder. S2: The precursor powder is first phosphated by reacting with PH3 in an oxygen-free environment, and then fluorinated by reacting with HF to obtain (FeCoNiCuMn)P2 / (FeCoNiCuMn)F2 heterogeneous nanoparticles. After washing with water, the high-entropy phosphorus-fluoride nanoparticle catalyst is obtained. The phosphated time is 2-3 h and the fluorinated time is 15-30 min.

2. The method for preparing the high-entropy phosphorus-fluoride nanoparticle catalyst according to claim 1, characterized in that, The aerosol droplets have a size of 2–4 μm.

3. The method for preparing the high-entropy phosphorus-fluoride nanoparticle catalyst according to claim 1, characterized in that, The specific process of the reaction between the precursor powder and PH3 in step S2 is as follows: NaH2PO2 is placed upstream of the reactor, the precursor powder is spread downstream of the reactor, inert gas is introduced from upstream to downstream, and the reactor is heated to thermally decompose NaH2PO2. The PH3 produced by thermal decomposition is carried downstream by the inert gas to react with the precursor powder in a phosphating reaction.

4. The method for preparing the high-entropy phosphorus-fluoride nanoparticle catalyst according to claim 3, characterized in that, The phosphating reaction is carried out at a temperature of 250–550 °C.

5. The method for preparing the high-entropy phosphorus-fluoride nanoparticle catalyst according to claim 2, characterized in that, The specific process of the reaction between the precursor powder and HF in step S2 is as follows: NH4F is placed upstream of the reactor, the precursor powder is spread downstream of the reactor, inert gas is introduced from upstream to downstream, and the reactor is heated to thermally decompose NH4F. The HF produced by thermal decomposition is carried downstream by the inert gas to react with the precursor powder in a fluorination reaction.

6. The method for preparing the high-entropy phosphorus-fluoride nanoparticle catalyst according to claim 5, characterized in that, The fluorination reaction is carried out at a temperature of 300–700 °C.

7. The method for preparing the high-entropy phosphorus-fluoride nanoparticle catalyst according to any one of claims 3 to 5, characterized in that, The inert gas is Ar, and the Ar gas flow rate is 50 ml / min during phosphating and fluorination; NaH2PO2 and NH4F are supplied in excess.

8. The method for preparing the high-entropy phosphorus-fluoride nanoparticle catalyst according to claim 7, characterized in that, The ammonium hydroxide solution is selected from ammonia water with an ammonia concentration of ≥20wt%.

9. The high-entropy phosphorus-fluoride nanoparticle catalyst prepared by the preparation method according to any one of claims 1 to 8.

10. An oxygen evolution electrode prepared using the high-entropy phosphorus-fluoride nanoparticle catalyst of claim 9.

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