Electrocatalyst with hollow nanocage loaded with high-entropy alloy as well as preparation method and application of electrocatalyst

Abstract

The invention belongs to the technical field of oxygen reduction catalysts, and discloses a hollow nanocage loaded high-entropy alloy electrocatalyst and a preparation method and application thereof. The preparation method comprises the following steps: synthesizing PS balls through an emulsion polymerization method, mixing, stirring and aging a solution prepared from 2-methylimidazole, cobalt nitrate and zinc nitrate in methanol and the PS balls, then adding metal precursors of iron, nickel and copper, and carrying out washing, drying, heat treatment and concentrated nitric acid etching to prepare NC-CoZnFeNiCu. The high-entropy alloy is located on the carbon nanocage, multiple active sites are formed due to the compression strain caused by the ultra-small bending carbon layer and the good synergistic coordination effect of the high-entropy alloy, and the reaction potential barrier of oxygen reduction is effectively reduced. The oxygen reduction performance of the material is superior to that of commercial Pt / C, the half-wave potential is 0.896 V, and the dynamic current density is 31.88 mA / cm < 2 >. By combining the structures of the high-entropy alloy and the hollow nanocage, the electron conduction capability of the catalyst is enhanced, and the performance of the oxygen reduction reaction is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of oxygen reduction catalysts, and in particular to an electrocatalyst. Background Art

[0002] With the continuous development of human society, the demand for clean energy and efficient catalysts has become more urgent. In the energy transition, the oxygen reduction reaction (ORR) is a key reaction in energy conversion systems such as fuel cells and metal-air batteries. However, in the current practical application of the ORR reaction, it mainly faces problems such as high reaction overpotential, slow kinetics, and poor catalyst stability. In addition, traditional ORR catalysts mostly rely on precious metals, such as platinum (Pt), which are difficult to meet the needs of large-scale applications due to their high cost and limited resources. These problems have promoted a wave of research on cheap but efficient non-precious metal catalysts.

[0003] In recent years, high entropy alloys have attracted widespread attention due to their multi-component, strong mixing, good chemical and thermal stability, and excellent catalytic performance, especially in the field of ORR. By loading high entropy alloys on carbon-based materials, not only can the conductivity of the catalyst be improved, but also the activity of the oxygen reduction reaction can be improved through the synergistic effect of the multi-metal in the alloy. The high entropy alloy formed on the carrier helps to improve the distribution of metal ions, increase electrochemical stability, and optimize the adsorption and reduction process of oxygen molecules, thereby partially solving the main problems in the current ORR. For example, the patent number CN11409418A discloses a method for preparing a high entropy alloy oxygen reduction electrocatalyst supported by a carbon material, which adopts a method of forming a coating layer on the surface of platinum carbon to adsorb metal ions, and through a thermal diffusion process, the metal ions and platinum nanoparticles form a high entropy alloy, which is then acid-washed and dried. Although this strategy avoids the subsequent carrier loading process, maintains the dispersibility of the alloy, and exhibits good oxygen reduction performance, it fails to completely solve the high cost and dependence on precious metals. Therefore, how to use cheaper metal components and innovative alloying strategies to reduce dependence on precious metals while improving the catalytic efficiency and stability in oxygen reduction reactions has become an important issue in the clean energy transition. Summary of the invention

[0004] In view of the above technical problems, the present invention proposes a hollow nanocage-loaded high-entropy alloy electrocatalyst and a preparation method and application thereof.

[0005] To achieve the above object, the technical solution of the present invention is implemented as follows:

[0006] A method for preparing a hollow nanocage-loaded high entropy alloy electrocatalyst comprises the following steps:

[0007] (1) Styrene (C 8 H8 ) was dispersed in deionized water and potassium persulfate (K 2 S 2 O 8 ) solution, heating and reacting under nitrogen protection, and obtaining PS seeds after centrifugation; dispersing the PS seeds in deionized water, adding styrene and potassium persulfate solution, heating and reacting under nitrogen protection, and washing the PS balls after centrifugation;

[0008] (2) dispersing PS spheres in an ethanol solution of polyvinyl pyrrolidone, stirring at room temperature, centrifuging, and dispersing in a methanol solution to obtain a PS sphere solution;

[0009] (3) To Co(NO 3 ) 2 6H 2 O and Zn(NO 3 ) 2 6H 2 Add the PS ball solution to the methanol solution of 2-methylimidazole and FeCl 3 6H 2 O、NiCl 2 6H 2 O and CuCl 2 ·4H 2 O, stirring to obtain a mixed solution II, aging, washing and drying to obtain a product;

[0010] (4) The product of step (3) is subjected to staged calcination treatment and concentrated acid etching to obtain NC-CoZnFeNiCu, i.e., a hollow nanocage-supported high entropy alloy electrocatalyst.

[0011] In the above step (1), the mass of potassium persulfate required for each milliliter of styrene is 8.8-11.3 mg; the mass ratio of PS seed to styrene is (0.6-0.9):1; the heating reaction temperature is 60-75°C and the time is 20-26h.

[0012] Wherein, the concentration of the polyvinyl pyrrolidone ethanol solution in the above step (2) is 30-70 mg / mL, and 300-650 mg of PS spheres are added to each mL of the polyvinyl pyrrolidone ethanol solution.

[0013] The concentration of the PS ball solution in the above step (2) is 100-350 mg / mL.

[0014] In the above step (3), the Co(NO 3 ) 2 6H 2 O、Zn(NO 3 ) 2 6H 2 O and FeCl3 6H 2 The mass ratio of O is 1:(0.5-2):(0.012-0.12); FeCl 3 6H 2 O、NiCl 2 6H 2 O and CuCl 2 ·4H 2 The mass ratio of O is 1:(0.8-3.1):(0.8-1.5).

[0015] The concentration of the methanol solution of 2-methylimidazole in step (3) is 10-15 mg / mL; Co(NO 3 ) 2 6H 2 O and Zn(NO 3 ) 2 6H 2 O in methanol solution Co(NO 3 ) 2 6H 2 The concentration of O is 0.005-0.016 mol / L.

[0016] In the above step (3), the mixed solution II contains Co(NO 3 ) 2 6H 2 O and Zn(NO 3 ) 2 6H 2 The volume ratio of the methanol solution of O, the PS ball solution and the methanol solution of 2-methylimidazole is (100-150):(1-3):(200-250); the aging temperature is room temperature and the time is 1.5-3h.

[0017] The staged calcination treatment in the above step (4) refers to heating to 300-400°C at a heating rate of 2-6°C / min in an argon atmosphere, calcining for 1.5-3h, and then heating to 750-850°C at a heating rate of 2-6°C / min, calcining for 1.5-3h.

[0018] The concentrated acid etching in the above step (4) refers to treatment with 0.5-2M nitric acid for 16-28 hours.

[0019] The hollow nanocage loaded high entropy alloy electrocatalyst prepared by the above-mentioned preparation method. The hollow nanocage loaded non-precious high entropy alloy electrocatalyst prepared by the above-mentioned preparation method presents a unique hollow structure, so that the high entropy alloy is evenly loaded on the surface of the hollow nanocage. Thanks to this unique structural design, the electrocatalyst exhibits a large specific surface area, thereby increasing the contact opportunity between the catalyst and the reactant. The introduction of a variety of non-precious metal elements to form a high entropy alloy further improves the electrochemical stability and corrosion resistance of the catalyst through the synergistic effect between the elements, showing excellent catalytic performance, which not only reduces the dependence on precious metals, but also improves the catalytic efficiency and reaction rate, and effectively enhances the catalytic activity of ORR.

[0020] Application of the above-mentioned hollow nanocage-loaded high entropy alloy electrocatalyst in energy storage and conversion devices.

[0021] Furthermore, the above hollow nanocage-loaded high entropy alloy electrocatalyst is used in oxygen reduction reaction under alkaline conditions.

[0022] The beneficial effects produced by the present invention are:

[0023] (1) Unique hollow structure design: The electrocatalyst of high entropy alloy loaded by hollow nanocages exhibits a unique hollow structure, which makes the high entropy alloy evenly distributed on the surface of carbon spheres. This design not only increases the specific surface area, but also provides more reaction sites, thus significantly improving the contact opportunities between the catalyst and the reactants and promoting the reaction. The dynamic current density reaches 31.88 mA cm -2 .

[0024] (2) Enhanced electrochemical stability: By introducing a variety of non-precious metal elements to form a high-entropy alloy, the catalyst exhibits excellent electrochemical stability and corrosion resistance. The synergistic effect between the elements enables the catalyst to maintain good catalytic performance during long-term operation, ensuring its reliability in practical applications. After 10,000 CV scans, its half-wave potential is only 3.7 mV attenuated compared to the initial LSV curve.

[0025] (3) Excellent catalytic performance and reaction rate: The prepared catalyst exhibited excellent electrochemical performance in ORR, with a half-wave potential of 0.896 V and a Tafel slope of 47 mV dec. -1 , showing high reaction rate and efficiency. This indicates its broad application prospects in energy storage and conversion devices.

[0026] (4) Lower cost: The NC-CoZnFeNiCu prepared in the present invention does not contain precious metals. This design not only reduces the production cost, but also makes the catalyst more economical in industrial production, thus meeting the actual needs of large-scale ORR. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 Scanning electron microscope image of NC-CoZnFeNiCu.

[0029] Figure 2 This is the X-ray diffraction spectrum of NC-CoZnFeNiCu.

[0030] Figure 3 This is the overall XPS test spectrum of the NC-CoZnFeNiCu catalyst prepared in Example 1.

[0031] Figure 4 This is the ORR linear cyclic voltammetry curve.

[0032] Figure 5 RDE polarization curve of NC-CoZnFeNiCu catalyst before and after 10000 accelerated durability tests. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example 1

[0035] The preparation method of a hollow nanocage-loaded high entropy alloy electrocatalyst of this embodiment comprises the following steps:

[0036] (1) Disperse 4 mL of styrene in 33.5 mL of deionized water and add 2.5 mL of 18 mg mL -1The potassium persulfate solution was heated at 70 °C for 24 h under nitrogen protection, and the PS seeds were obtained after centrifugation. 3 g of PS seeds were dispersed in 33.5 mL of deionized water, and 4 mL of styrene and 2.5 mL, 18 mg mL -1 Potassium persulfate solution was heated at 70°C for 24 h under nitrogen protection to wash the PS balls after centrifugation;

[0037] (2) Disperse PS spheres (6 g) in 10 mL, 50 mg mL -1 The ethanol solution of polyvinyl pyrrolidone was stirred at room temperature for 12 hours, collected by centrifugation at 8000 rpm, washed with ethanol 3-4 times, dispersed in 30 mL of methanol to obtain a PS ball solution (concentration of 200 mg / mL); 0.69 g of 2-methylimidazole was dissolved in 50 mL of methanol solution to obtain a methanol solution of 2-methylimidazole.

[0038] (3) Put Co(NO 3 ) 2 6H 2 O (0.16 mmol) and Zn(NO 3 ) 2 6H 2 O (0.32 mmol) was dissolved in 24 mL of methanol solution, 0.4 mL of PS ball solution was added, and after stirring at room temperature, 40 mL of 2-methylimidazole methanol solution and 2 mg of FeCl 3 6H 2 O, 2 mg NiCl 2 6H 2 O and 2 mg CuCl 2 ·4H 2 O, stirring to obtain a mixed solution, aging at room temperature for 2 h, washing, and drying to obtain a product;

[0039] (4) The product of step (3) was sintered at 350°C for 2 h and then at 800°C for 2 h, with a heating rate of 4°C min -1 Finally, the hollow nanocage-supported high-entropy alloy electrocatalyst (NC-CoZnFeNiCu) was obtained by etching with 1 M nitric acid for 24 h.

[0040] Scanning electron microscope image of the hollow nanocage-supported high entropy alloy electrocatalyst prepared in this example ( Figure 1 ) It can be seen that the hollow nanocages are loaded with non-precious high-entropy alloy electrocatalysts, each cube has a size of about 500nm, a uniform morphology, and shows an ultra-thin core-shell structure.

[0041] The X-ray diffraction pattern of the electrocatalyst prepared in this example is as follows: Figure 2The characteristic diffraction peak of the sample is located at 44° at 2θ. There is a broad diffraction peak attributed to NC but no narrow crystal diffraction peak, indicating that NC-CoZnFeNiCu has no single metal clusters and particles.

[0042] The X-ray photoelectron spectrum of the electrocatalyst prepared in this example is as follows: Figure 3 , it can be seen that zinc, copper, nickel, cobalt, iron, oxygen, nitrogen and carbon elements are present in the composite material.

[0043] Example 2

[0044] The preparation method of a hollow nanocage-loaded high entropy alloy electrocatalyst of this embodiment comprises the following steps:

[0045] (1) Disperse 3.8 mL of styrene in 33.5 mL of deionized water and add 2.5 mL of 16 mg mL -1 The potassium persulfate solution was heated at 70 °C for 24 h under nitrogen protection, and the PS seeds were obtained after centrifugation. 2.5 g of PS seeds were dispersed in 33.5 mL of deionized water, and 3.8 mL of styrene and 2.5 mL, 16 mg mL -1 Potassium persulfate solution was heated at 70°C for 24 h under nitrogen protection to wash the PS balls after centrifugation;

[0046] (2) Disperse PS spheres (5 g) in 8 mL, 30 mg mL -1 The ethanol solution of polyvinyl pyrrolidone was stirred at room temperature for 12 hours, collected by centrifugation at 8000 rpm, washed with ethanol 3-4 times, dispersed in 45 mL of methanol to obtain a PS ball solution (concentration of 110 mg / mL); 0.5 g of 2-methylimidazole was dissolved in 50 mL of methanol solution to obtain a methanol solution of 2-methylimidazole.

[0047] (3) Put Co(NO 3 ) 2 6H 2 O (0.16 mmol) and Zn(NO 3 ) 2 6H 2 O (0.16 mmol) was dissolved in 20 mL of methanol solution, 0.2 mL of PS ball solution was added, and after stirring at room temperature, 40 mL of 2-methylimidazole methanol solution and 2 mg of FeCl 3 6H 2 O, 1.6 mg NiCl 2 6H 2 O and 2 mg CuCl 2 ·4H 2 O, stirring to obtain a mixed solution, aging at room temperature for 1.5 h, washing, and drying to obtain the product;

[0048] (4) The product of step (3) was sintered at 300°C for 1.5 h and then at 750°C for 1.5 h, with a heating rate of 2°C min -1 Finally, the hollow nanocage-supported high-entropy alloy electrocatalyst (NC-CoZnFeNiCu) was obtained by etching with 0.5 M nitric acid for 16 h.

[0049] Example 3

[0050] The preparation method of a hollow nanocage-loaded high entropy alloy electrocatalyst of this embodiment comprises the following steps:

[0051] (1) Disperse 5.4 mL of styrene in 33.5 mL of deionized water and add 2.5 mL of 19 mg mL -1 The potassium persulfate solution was heated at 70 °C for 24 h under nitrogen protection, and the PS seeds were obtained after centrifugation. 4 g of PS seeds were dispersed in 33.5 mL of deionized water, and 5.4 mL of styrene and 2.5 mL, 19 mg mL -1 Potassium persulfate solution was heated at 70°C for 24 h under nitrogen protection to wash the PS balls after centrifugation;

[0052] (2) Disperse PS spheres (6.5 g) in 15 mL, 70 mg mL -1 The ethanol solution of polyvinyl pyrrolidone was stirred at room temperature for 12 hours, collected by centrifugation at 8000 rpm, washed with ethanol 3-4 times, dispersed in 20 mL of methanol to obtain a PS ball solution (concentration of 325 g / mL); 0.75 g of 2-methylimidazole was dissolved in 50 mL of methanol solution to obtain a methanol solution of 2-methylimidazole.

[0053] (3) Put Co(NO 3 ) 2 6H 2 O (0.32 mmol) and Zn(NO 3 ) 2 6H 2 O (0.32 mmol) was dissolved in 30 mL of methanol solution, 0.6 mL of PS ball solution was added, and after stirring at room temperature, 40 mL of 2-methylimidazole methanol solution and 1.6 mg of FeCl 3 6H 2 O, 5 mg NiCl 2 6H 2 O and 2.4 mg CuCl 2 ·4H 2 O, stirring to obtain a mixed solution, aging at room temperature for 3 h, washing, and drying to obtain a product;

[0054] (4) The product of step (3) was sintered at 400°C for 3 h and then at 850°C for 3 h, with a heating rate of 6°C min -1 Finally, the hollow nanocage-supported high-entropy alloy electrocatalyst (NC-CoZnFeNiCu) was obtained by etching with 2 M nitric acid for 28 h.

[0055] Example 4

[0056] The preparation method of a hollow nanocage-loaded high entropy alloy electrocatalyst of this embodiment comprises the following steps:

[0057] (1) Disperse 3.8 mL of styrene in 33.5 mL of deionized water and add 2.5 mL of 16 mg mL -1 The potassium persulfate solution was heated at 70 °C for 24 h under nitrogen protection, and the PS seeds were obtained after centrifugation. 2.5 g of PS seeds were dispersed in 33.5 mL of deionized water, and 3.8 mL of styrene and 2.5 mL, 16 mg mL -1 Potassium persulfate solution was heated at 70°C for 24 h under nitrogen protection to wash the PS balls after centrifugation;

[0058] (2) Disperse PS spheres (6.5 g) in 8 mL, 70 mg mL -1 The ethanol solution of polyvinyl pyrrolidone was stirred at room temperature for 12 hours, collected by centrifugation at 8000 rpm, washed with ethanol 3-4 times, dispersed in 20 mL of methanol to obtain a PS ball solution (concentration of 325 g / mL); 0.6 g of 2-methylimidazole was dissolved in 60 mL of methanol solution to obtain a methanol solution of 2-methylimidazole.

[0059] (3) Put Co(NO 3 ) 2 6H 2 O (0.32 mmol) and Zn(NO 3 ) 2 6H 2 O (0.16 mmol) was dissolved in 24 mL of methanol solution, 0.2 mL of PS ball solution was added, and after stirring at room temperature, 50 mL of 2-methylimidazole methanol solution and 2 mg of FeCl 3 6H 2 O, 1.6 mg NiCl 2 6H 2 O and 2 mg CuCl 2 ·4H 2 O, stirring to obtain a mixed solution, aging at room temperature for 1.5 h, washing, and drying to obtain the product;

[0060] (4) The product of step (3) was sintered at 400°C for 2 h and then at 750°C for 2 h, with a heating rate of 2°C min -1 Finally, the hollow nanocage-supported high-entropy alloy electrocatalyst (NC-CoZnFeNiCu) was obtained by etching with 0.5 M nitric acid for 28 h.

[0061] Example 5

[0062] The preparation method of a hollow nanocage-loaded high entropy alloy electrocatalyst of this embodiment comprises the following steps:

[0063] (1) Disperse 5.4 mL of styrene in 33.5 mL of deionized water and add 2.5 mL of 19 mg mL -1 The potassium persulfate solution was heated at 70 °C for 24 h under nitrogen protection, and the PS seeds were obtained after centrifugation. 4 g of PS seeds were dispersed in 33.5 mL of deionized water, and 5.4 mL of styrene and 2.5 mL, 19 mg mL -1 Potassium persulfate solution was heated at 70°C for 24 h under nitrogen protection to wash the PS balls after centrifugation;

[0064] (2) Disperse PS spheres (5 g) in 10 mL, 50 mg mL -1 The ethanol solution of polyvinyl pyrrolidone was stirred at room temperature for 12 hours, collected by centrifugation at 8000 rpm, washed with ethanol 3-4 times, dispersed in 45 mL of methanol to obtain a PS ball solution (concentration of 110 g / mL); 0.9 g of 2-methylimidazole was dissolved in 60 mL of methanol solution to obtain a methanol solution of 2-methylimidazole.

[0065] (3) Put Co(NO 3 ) 2 6H 2 O (0.32 mmol) and Zn(NO 3 ) 2 6H 2 O (0.16 mmol) was dissolved in 24 mL of methanol solution, 0.6 mL of PS ball solution was added, and after stirring at room temperature, 50 mL of 2-methylimidazole methanol solution and 1.6 mg of FeCl 3 6H 2 O, 2 mg NiCl 2 6H 2 O and 2.4 mg CuCl 2 ·4H 2 O, stirring to obtain a mixed solution, aging at room temperature for 3 h, washing, and drying to obtain a product;

[0066] (4) The product of step (3) was sintered at 300°C for 2 h and then at 850°C for 2 h, with a heating rate of 6°C min -1 Finally, the hollow nanocage-supported high-entropy alloy electrocatalyst (NC-CoZnFeNiCu) was obtained by etching with 2 M nitric acid for 16 h.

[0067] Example 6

[0068] The preparation method of a hollow nanocage-loaded high entropy alloy electrocatalyst of this embodiment comprises the following steps:

[0069] (1) Disperse 4 mL of styrene in 33.5 mL of deionized water and add 2.5 mL of 18 mg mL -1 The potassium persulfate solution was heated at 60 °C for 26 h under nitrogen protection, and the PS seeds were obtained after centrifugation. 3 g of PS seeds were dispersed in 33.5 mL of deionized water, and 5.4 mL of styrene and 2.5 mL, 19 mg mL -1 Potassium persulfate solution was heated at 60°C for 26 h under nitrogen protection to wash the PS balls after centrifugation;

[0070] (2) Disperse PS spheres (6.5 g) in 10 mL, 50 mg mL -1 The ethanol solution of polyvinyl pyrrolidone was stirred at room temperature for 12 hours, collected by centrifugation at 8000 rpm, washed with ethanol 3-4 times, dispersed in 18.5 mL of methanol to obtain a PS ball solution (concentration of 350 mg / mL); 0.69 g of 2-methylimidazole was dissolved in 50 mL of methanol solution to obtain a methanol solution of 2-methylimidazole.

[0071] (3) Put Co(NO 3 ) 2 6H 2 O (0.32 mmol) and Zn(NO 3 ) 2 6H 2 O (0.32 mmol) was dissolved in 20 mL of methanol solution, 0.4 mL of PS ball solution was added, and after stirring at room temperature, 45 mL of 2-methylimidazole methanol solution and 1 mg of FeCl 3 6H 2 O, 2 mg NiCl 2 6H 2 O and 0.8 mg CuCl 2 ·4H 2 O, stirring to obtain a mixed solution, aging at room temperature for 2 h, washing, and drying to obtain a product;

[0072] (4) The product of step (3) was sintered at 350°C for 2 h and then at 800°C for 2 h, with a heating rate of 4°C min -1 Finally, the hollow nanocage-supported high-entropy alloy electrocatalyst (NC-CoZnFeNiCu) was obtained by etching with 1 M nitric acid for 24 h.

[0073] Example 7

[0074] The preparation method of a hollow nanocage-loaded high entropy alloy electrocatalyst of this embodiment comprises the following steps:

[0075] (1) Disperse 4 mL of styrene in 33.5 mL of deionized water and add 2.5 mL of 18 mg mL -1 The potassium persulfate solution was heated at 75 °C for 20 h under nitrogen protection, and the PS seeds were obtained after centrifugation. 3.3 g of PS seeds were dispersed in 33.5 mL of deionized water, and 4 mL of styrene and 2.5 mL, 18 mg mL -1 Potassium persulfate solution was heated at 75°C for 20 h under nitrogen protection to wash the PS spheres after centrifugation;

[0076] (2) Disperse PS spheres (3 g) in 10 mL, 50 mg mL -1 The ethanol solution of polyvinyl pyrrolidone was stirred at room temperature for 12 hours, collected by centrifugation at 8000 rpm, washed with ethanol 3-4 times, dispersed in 30 mL of methanol to obtain a PS ball solution (concentration of 100 mg / mL); 0.69 g of 2-methylimidazole was dissolved in 50 mL of methanol solution to obtain a methanol solution of 2-methylimidazole.

[0077] (3) Put Co(NO 3 ) 2 6H 2 O (0.16 mmol) and Zn(NO 3 ) 2 6H 2 O (0.32 mmol) was dissolved in 30 mL of methanol solution, 0.4 mL of PS ball solution was added, and after stirring at room temperature, 40 mL of 2-methylimidazole methanol solution and 5 mg of FeCl 3 6H 2 O, 5 mg NiCl 2 6H 2 O and 5 mg CuCl 2 ·4H 2 O, stirring to obtain a mixed solution, aging at room temperature for 2 h, washing, and drying to obtain a product;

[0078] (4) The product of step (3) was sintered at 350°C for 2 h and then at 800°C for 2 h, with a heating rate of 4°C min-1 Finally, the hollow nanocage-supported high-entropy alloy electrocatalyst (NC-CoZnFeNiCu) was obtained by etching with 1 M nitric acid for 24 h.

[0079] Comparative Example 1

[0080] The preparation method of the hollow nanocage-supported alloy electrocatalyst of this comparative example is different from that of Example 1 in that the prepared alloy contains only Zn and Co, and comprises the following steps:

[0081] (1) Disperse 4 mL of styrene in 33.5 mL of deionized water and add 2.5 mL of 18 mg mL -1 Potassium persulfate (K 2 S 2 O 8 ) solution, heated at 70 ° C for 24 h under nitrogen protection, and centrifuged to obtain PS seeds; 3 g of PS seeds were dispersed in 33.5 mL of deionized water, and 4 mL of styrene and 2.5 mL, 18 mg mL -1 Potassium persulfate solution was heated at 70°C for 24 h under nitrogen protection to wash the PS balls after centrifugation;

[0082] (2) Disperse PS spheres (6 g) in 10 mL, 50 mg mL -1 The ethanol solution of polyvinyl pyrrolidone was stirred at room temperature for 12 hours, collected by centrifugation at 8000 rpm, washed with ethanol 3-4 times, dispersed in 30 mL of methanol to obtain a PS ball solution (concentration of 200 g / mL); 0.69 g of 2-methylimidazole was dissolved in 50 mL of methanol solution to obtain a methanol solution of 2-methylimidazole.

[0083] (3) Put Co(NO 3 ) 2 6H 2 O (0.16 mmol) and Zn(NO 3 ) 2 6H 2 O (0.32 mmol) was dissolved in 24 mL of methanol solution, 0.4 mL of PS ball solution was added, and after stirring at room temperature, 40 mL of 2-methylimidazole methanol solution was added, and the mixture was stirred to obtain a mixed solution, which was aged at room temperature for 1 h, washed, and dried to obtain the product;

[0084] (4) The product of step (3) was sintered at 350°C for 2 h and then at 800°C for 2 h, with a heating rate of 4°C min -1 Finally, the hollow nanocage-supported alloy electrocatalyst (NC-CoZn) was obtained by etching with 1 M nitric acid for 24 h.

[0085] Application Examples

[0086] The NC-CoZnFeNiCu obtained in Example 1, the NC-CoZn obtained in Comparative Example 1, and the Pt / C catalyst purchased on the market were used to prepare electrocatalysts for oxygen reduction reaction.

[0087] In the electrocatalytic oxygen reduction process, the specific steps for preparing the working electrode are as follows: 5 mg of the catalyst was dispersed in 1 mL of a water-isopropanol solution with a volume ratio of 3:2, and ultrasonicated for 1 h to make the catalyst uniformly dispersed in the water-isopropanol mixed solution, and then 20 μL of Nafion solution (5 wt %) was added and ultrasonicated for 0.5 h to prepare a uniform 5 mg mL -1 The catalyst ink was prepared by evenly coating 10 μL of the catalyst ink (containing 50 μg of catalyst) on a disc glassy carbon electrode with a diameter of 5 mm.

[0088] The above working electrode was tested for oxygen reduction performance using linear sweep voltammetry (LSV). The specific test method is as follows: 2 The oxygen reduction performance of the electrode was studied by linear sweep voltammetry in 1 M KOH solution at a speed of 1600 rpm and 5 mV s -1 The test is carried out at a scan rate of . The background current is deducted from the measured current through iR correction to eliminate the influence of capacitive current. The half-wave potential of the catalyst can be obtained based on the curve, so as to compare the performance of different catalysts.

[0089] The linear sweep voltammetry curve of the hollow nanocage-supported high entropy alloy electrocatalyst prepared by the present invention is as follows: Figure 4 As can be seen from the figure, the half-wave potential of the sample prepared in Example 1 is 0.896 V, and the dynamic current density is 31.88 mA cm -2 , while the half-wave potential of Pt / C catalyst is 0.833 V and the dynamic current density is 3.61 mA cm -2 The half-wave potential of the NC-CoZn catalyst is 0.811 V and the dynamic current density is 1.01 mA cm -2 , these values ​​are significantly higher than the overpotential of the obtained sample. The test results show that NC-CoZnFeNiCu has excellent ORR catalytic activity. The specific data of the half-wave potential and dynamic current density of the catalysts prepared in different embodiments and comparative examples, and Pt / C are shown in Table 1.

[0090] Table 1. Half-wave potential and dynamic current density

[0091] Group Half-wave potential / V <![CDATA[Dynamic current density / mA cm -2 > Example 1 0.896 31.88 Example 2 0.883 22.54 Example 3 0.876 20.25 Example 4 0.879 20.62 Example 5 0.865 18.36 Example 6 0.857 15.23 Example 7 0.860 16.38 Comparative Example 1 0.811 1.01 Pt / C Catalyst 0.833 3.61

[0092] As can be seen from Table 1, the catalyst of the embodiment shows higher dynamic current density and half-wave potential than the comparative example 1 and the Pt / C catalyst, and has higher reaction activity and better catalytic efficiency.

[0093] The working electrode was subjected to an accelerated durability test for oxygen reduction cycle stability. The specific test method is as follows: 2 The scanning speed was 10 mV s at 1600 rpm in 0.1 M KOH solution. -1 The LSV curve was measured, and then the same solution was scanned for 10,000 cycles of CV (scan rate was 100 mV / S, and scanning was performed only within the voltage range where the redox peak was located). The LSV curve was measured again under the same conditions, and the stability of the catalyst was evaluated by comparing the decay of the half-wave potential of the two LSV curves. The stability curve of the obtained hollow carbon sphere-supported non-precious high-entropy alloy electrocatalyst is shown in Figure 2. Figure 5 The results showed that after 10,000 CV scans, the half-wave potential was attenuated by only 3.7 mV compared with the initial LSV curve, indicating that the NC-CoZnFeNiCu catalyst has good alkaline cycling stability.

[0094] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a hollow nanocage-loaded high entropy alloy electrocatalyst, characterized in that: Here are the steps: (1) dispersing styrene in deionized water, adding potassium persulfate solution, heating and reacting under nitrogen protection, and centrifuging to obtain PS seeds; dispersing PS seeds in deionized water, adding styrene and potassium persulfate solution, heating and reacting under nitrogen protection, and washing the PS balls after centrifugation; (2) dispersing PS spheres in an ethanol solution of polyvinyl pyrrolidone, stirring at room temperature, centrifuging, and dispersing in a methanol solution to obtain a PS sphere solution; (3) Add the PS ball solution to the methanol solution of Co(NO3)2·6H2O and Zn(NO3)2·6H2O, stir at room temperature, then add the methanol solution of 2-methylimidazole, FeCl3·6H2O, NiCl2·6H2O and CuCl2·4H2O, stir to obtain a mixed solution, age, wash and dry to obtain the product; (4) The product of step (3) is subjected to staged calcination treatment and concentrated acid etching to obtain NC-CoZnFeNiCu, i.e., a hollow nanocage-supported high entropy alloy electrocatalyst.

2. The method for preparing the hollow nanocage-supported high entropy alloy electrocatalyst according to claim 1, characterized in that: In the step (1), the mass of potassium persulfate required for each milliliter of styrene is 8.8-11.3 mg; the mass ratio of PS seed to styrene is (0.6-0.9):1; the heating reaction temperature is 60-75°C and the time is 20-26 hours.

3. The method for preparing the hollow nanocage-loaded high entropy alloy electrocatalyst according to claim 2, characterized in that: The concentration of the PS ball solution in step (2) is 100-350 mg / mL.

4. The method for preparing the hollow nanocage-supported high entropy alloy electrocatalyst according to claim 3, characterized in that: In the step (3), the mass ratio of Co(NO3)2·6H2O, Zn(NO3)2·6H2O and FeCl3·6H2O in the mixed solution is 1:(0.5-2):(0.012-0.12); the mass ratio of FeCl3·6H2O, NiCl2·6H2O and CuCl2·4H2O is 1:(0.8-3.1):(0.8-1.5).

5. The method for preparing the hollow nanocage-supported high entropy alloy electrocatalyst according to claim 4, characterized in that: The concentration of the methanol solution of 2-methylimidazole in the step (3) is 10-15 mg / mL; the concentration of Co(NO3)2·6H2O in the methanol solution of Co(NO3)2·6H2O and Zn(NO3)2·6H2O is 0.005-0.016 mol / L.

6. The method for preparing the hollow nanocage-supported high entropy alloy electrocatalyst according to claim 5, characterized in that: In the step (3), the volume ratio of the methanol solution of Co(NO3)2·6H2O and Zn(NO3)2·6H2O, the PS ball solution and the methanol solution of 2-methylimidazole is (100-150):(1-3):(200-250); the aging temperature is room temperature and the time is 1.5-3h.

7. The method for preparing the hollow nanocage-supported high entropy alloy electrocatalyst according to claim 6, characterized in that: The staged calcination treatment in step (4) refers to heating to 300-400°C at a heating rate of 2-6°C / min in an argon atmosphere, calcining for 1.5-3h, and then heating to 750-850°C at a heating rate of 2-6°C / min, calcining for 1.5-3h.

8. The method for preparing the hollow nanocage-supported high entropy alloy electrocatalyst according to claim 7, characterized in that: The concentrated acid etching in step (4) refers to treatment with 0.5-2M nitric acid for 16-28 hours.

9. A hollow nanocage-loaded high entropy alloy electrocatalyst prepared by the preparation method of claim 1.

10. Use of the hollow nanocage-loaded high entropy alloy electrocatalyst according to claim 9 in energy storage and conversion devices.

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