An electrocatalyst for high-entropy alloy supported by hollow nanocages, its preparation method and application

Abstract

The application belongs to the technical field of oxygen reduction catalysts, and discloses an electrocatalyst of hollow nanocage loaded high-entropy alloy and a preparation method and application thereof. PS balls are synthesized by an emulsion polymerization method, a solution prepared by mixing 2-methyl imidazole with cobalt and zinc nitrate in methanol is mixed with the PS balls and stirred and aged, iron, nickel and copper metal precursors are added, and NC-CoZnFeNiCu is prepared through washing, drying, heat treatment and concentrated nitric acid etching. The high-entropy alloy is located on the carbon nanocage, and due to the compression strain caused by the ultra-small curved carbon layer and the good synergistic coordination effect of the high-entropy alloy, multiple active sites are formed, and the reaction barrier of oxygen reduction is effectively reduced. The oxygen reduction performance of the material is better than that of a 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 structure of the high-entropy alloy and the hollow nanocage, the electronic conduction capacity of the catalyst is enhanced, and the performance of the oxygen reduction reaction is significantly improved.

Description

Technical Field

[0001] This invention relates to the technical field of oxygen reduction catalysts, and more particularly to an electrocatalyst. Background Technology

[0002] With the continuous development of human society, the demand for clean energy and efficient catalysts is becoming increasingly 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, current practical applications of ORR reactions mainly face problems such as high reaction overpotential, slow kinetics, and poor catalyst stability. Furthermore, traditional ORR catalysts mostly rely on precious metals, such as platinum (Pt), which, due to their high cost and limited resources, are difficult to meet the needs of large-scale applications. These problems have spurred a surge of research into inexpensive yet efficient non-precious metal catalysts.

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

[0004] To address the aforementioned technical problems, this invention proposes an electrocatalyst for high-entropy alloys supported on hollow nanocages, its preparation method, and its application.

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

[0006] A method for preparing an electrocatalyst of high-entropy alloy supported on hollow nanocages, comprising the following steps:

[0007] (1) Styrene (C8H8) was dispersed in deionized water, potassium persulfate (K2S2O8) solution was added, and the reaction was carried out under nitrogen protection. After centrifugation, PS seeds were obtained. PS seeds were dispersed in deionized water, styrene and potassium persulfate solution were added, and the reaction was carried out under nitrogen protection. The PS balls were washed and centrifuged.

[0008] (2) The PS balls were dispersed in an ethanol solution of polyvinylpyrrolidone, and then stirred at room temperature, centrifuged, and dispersed in a methanol solution to obtain a PS ball solution.

[0009] (3) Add PS ball solution to the methanol solution of Co(NO3)2·6H2O and Zn(NO3)2·6H2O, stir at room temperature, add methanol solution of 2-methylimidazole, FeCl3·6H2O, NiCl2·6H2O and CuCl2·4H2O, stir to obtain mixed solution II, and after aging, washing and drying, obtain the product;

[0010] (4) After the product of step (3) is subjected to staged calcination and concentrated acid etching, NC-CoZnFeNiCu, namely, high entropy alloy electrocatalyst supported by hollow nanocage, is obtained.

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

[0012] In step (2) above, the concentration of the polyvinylpyrrolidone ethanol solution is 30-70 mg / mL, and 300-650 mg of PS balls are added to each milliliter of polyvinylpyrrolidone ethanol solution.

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

[0014] In step (3) above, the mass ratio of Co(NO3)2·6H2O, Zn(NO3)2·6H2O and FeCl3·6H2O in mixed solution II 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).

[0015] In step (3) above, the concentration of 2-methylimidazole in methanol solution is 10-15 mg / mL; the concentration of Co(NO3)2·6H2O in methanol solution of Co(NO3)2·6H2O and Zn(NO3)2·6H2O is 0.005-0.016 mol / L.

[0016] In step (3) above, the volume ratio of methanol solution of Co(NO3)2·6H2O and Zn(NO3)2·6H2O, PS ball solution and methanol solution of 2-methylimidazole in mixed solution II 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 step (4) above refers to first heating to 300-400℃ at a heating rate of 2-6℃ / min in an argon atmosphere and calcining for 1.5-3h, and then heating to 750-850℃ at a heating rate of 2-6℃ / min and calcining for 1.5-3h.

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

[0019] Electrocatalysts of high-entropy alloys supported on hollow nanocages were prepared using the above-described method. These electrocatalysts, using non-noble high-entropy alloys supported on hollow nanocages, exhibit a unique hollow structure, allowing the high-entropy alloy to be uniformly loaded onto the surface of the hollow nanocages. Thanks to this unique structural design, the electrocatalyst displays a large specific surface area, thereby increasing the contact opportunities between the catalyst and reactants. The introduction of multiple non-noble metal elements forms a high-entropy alloy, and through the synergistic effect between elements, further improves the electrochemical stability and corrosion resistance of the catalyst, exhibiting excellent catalytic performance. This not only reduces dependence on noble metals but also improves catalytic efficiency and reaction rate, effectively enhancing the catalytic activity of ORR (Organic Reactive Metal Ratio).

[0020] The above-mentioned hollow nanocage supported high-entropy alloy electrocatalysts are used in energy storage and conversion devices.

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

[0022] The beneficial effects of this invention are:

[0023] (1) Unique hollow structure design: The electrocatalyst, supported on a hollow nanocage, exhibits a unique hollow structure, allowing the high-entropy alloy to be uniformly distributed on the surface of the carbon spheres. This design not only increases the specific surface area but also provides more reaction sites, thereby significantly improving the contact opportunities between the catalyst and the reactants, promoting the reaction, and achieving a dynamic current density of 31.88 mA cm⁻¹. -2 .

[0024] (2) Enhanced electrochemical stability: By introducing multiple non-noble metal elements to form a high-entropy alloy, the catalyst exhibits excellent electrochemical stability and corrosion resistance. The synergistic effect between 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 decreased by only 3.7 mV compared to the initial LSV curve.

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

[0026] (4) Lower cost: The NC-CoZnFeNiCu prepared by this invention does not contain precious metals. This design not only reduces production costs, but also makes the catalyst more economical in industrial production, thus meeting the actual needs of large-scale ORR. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a scanning electron microscope image of NC-CoZnFeNiCu.

[0029] Figure 2 The X-ray diffraction pattern of NC-CoZnFeNiCu is shown.

[0030] Figure 3 The XPS spectra of the NC-CoZnFeNiCu catalyst prepared in Example 1 are shown.

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

[0032] Figure 5 The RDE polarization curves of the NC-CoZnFeNiCu catalyst before and after 10,000 accelerated durability tests are shown. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Example 1

[0035] The preparation method of the electrocatalyst of high-entropy alloy supported on hollow nanocage in this embodiment includes the following steps:

[0036] (1) Disperse 4 mL of styrene in 33.5 mL of deionized water, add 2.5 mL of 18 mg / mL solution. -1 A potassium persulfate solution was heated at 70°C for 24 hours under nitrogen protection, and the resulting solution was centrifuged to obtain PS seeds. 3g of PS seeds were dispersed in 33.5mL of deionized water, and 4mL of styrene and 2.5mL of 18mg / mL solution were added. -1 Potassium persulfate solution was heated at 70°C for 24 hours under nitrogen protection, and the PS spheres were washed and centrifuged.

[0037] (2) Disperse PS spheres (6g) in 10mL and 50mg mL of water. -1 An ethanol solution of polyvinylpyrrolidone was stirred at room temperature for 12 hours, collected by centrifugation at 8000 rpm, washed 3-4 times with ethanol, and 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) Dissolve Co(NO3)2·6H2O (0.16 mmol) and Zn(NO3)2·6H2O (0.32 mmol) in 24 mL of methanol solution, add 0.4 mL of PS ball solution, stir at room temperature, add 40 mL of 2-methylimidazole methanol solution, 2 mg FeCl3·6H2O, 2 mg NiCl2·6H2O and 2 mg CuCl2·4H2O, stir to obtain a mixed solution, age at room temperature for 2 h, wash and dry to obtain the product;

[0039] (4) The product from step (3) was sintered at 350℃ for 2 hours, and then sintered at 800℃ for 2 hours, with a heating rate of 4℃ / min for both times. -1 Finally, the catalyst was etched with 1M nitric acid for 24 hours to obtain a high-entropy alloy electrocatalyst (NC-CoZnFeNiCu) supported on a hollow nanocage.

[0040] Scanning electron microscope image of the hollow nanocage-supported high-entropy alloy electrocatalyst prepared in this embodiment ( Figure 1 It can be seen that the hollow nanocage supported non-precious high-entropy alloy electrocatalyst has a cube size of about 500 nm, uniform morphology, and shows an ultrathin core-shell structure.

[0041] The X-ray diffraction pattern of the electrocatalyst prepared in this embodiment is as follows: Figure 2 The sample's characteristic diffraction peaks are located at 2θ = 44°, with broad diffraction peaks belonging to NC and no narrow crystal diffraction peaks, indicating that NC-CoZnFeNiCu does not contain single metal clusters or particles.

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

[0043] Example 2

[0044] The preparation method of the electrocatalyst of high-entropy alloy supported on hollow nanocage in this embodiment includes the following steps:

[0045] (1) Disperse 3.8 mL of styrene in 33.5 mL of deionized water, add 2.5 mL of 16 mg / mL solution. -1 A potassium persulfate solution was heated at 70°C for 24 hours under nitrogen protection, and the resulting solution was centrifuged to obtain PS seeds. 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 of 16 mg / mL solution were added. -1 Potassium persulfate solution was heated at 70°C for 24 hours under nitrogen protection, and the PS spheres were washed and centrifuged.

[0046] (2) Disperse 5g of PS balls in 8mL of 30mg mL of water. -1 An ethanol solution of polyvinylpyrrolidone was stirred at room temperature for 12 hours, centrifuged at 8000 rpm, washed 3-4 times with ethanol, and 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) Dissolve Co(NO3)2·6H2O (0.16 mmol) and Zn(NO3)2·6H2O (0.16 mmol) in 20 mL of methanol solution, add 0.2 mL of PS ball solution, stir at room temperature, add 40 mL of 2-methylimidazole methanol solution, 2 mg FeCl3·6H2O, 1.6 mg NiCl2·6H2O and 2 mg CuCl2·4H2O, stir to obtain a mixed solution, age at room temperature for 1.5 h, wash and dry to obtain the product;

[0048] (4) The product from step (3) was sintered at 300℃ for 1.5 h, and then sintered at 750℃ for 1.5 h, with a heating rate of 2℃ / min for both times. -1 Finally, the catalyst was etched with 0.5M nitric acid for 16 hours to obtain a high-entropy alloy electrocatalyst (NC-CoZnFeNiCu) supported on hollow nanocages.

[0049] Example 3

[0050] The preparation method of the electrocatalyst of high-entropy alloy supported on hollow nanocage in this embodiment includes the following steps:

[0051] (1) Disperse 5.4 mL of styrene in 33.5 mL of deionized water, add 2.5 mL of 19 mg / mL solution. -1 A potassium persulfate solution was heated at 70°C for 24 hours under nitrogen protection, and the resulting solution was centrifuged to obtain PS seeds. 4 g of PS seeds were dispersed in 33.5 mL of deionized water, and 5.4 mL of styrene and 2.5 mL of 19 mg / mL solution were added. -1 Potassium persulfate solution was heated at 70°C for 24 hours under nitrogen protection, and the PS spheres were washed and centrifuged.

[0052] (2) Disperse PS spheres (6.5g) in 15mL and 70mg mL. -1 An ethanol solution of polyvinylpyrrolidone was stirred at room temperature for 12 hours, collected by centrifugation at 8000 rpm, washed 3-4 times with ethanol, and 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) Dissolve Co(NO3)2·6H2O (0.32 mmol) and Zn(NO3)2·6H2O (0.32 mmol) in 30 mL of methanol solution, add 0.6 mL of PS ball solution, stir at room temperature, add 40 mL of 2-methylimidazole methanol solution, 1.6 mg FeCl3·6H2O, 5 mg NiCl2·6H2O and 2.4 mg CuCl2·4H2O, stir to obtain a mixed solution, age at room temperature for 3 h, wash and dry to obtain the product;

[0054] (4) The product from step (3) was sintered at 400℃ for 3 hours, and then sintered at 850℃ for 3 hours, with a heating rate of 6℃ / min for both times. -1 Finally, the catalyst was etched with 2M nitric acid for 28 hours to obtain a high-entropy alloy electrocatalyst (NC-CoZnFeNiCu) supported on a hollow nanocage.

[0055] Example 4

[0056] The preparation method of the electrocatalyst of high-entropy alloy supported on hollow nanocage in this embodiment includes the following steps:

[0057] (1) Disperse 3.8 mL of styrene in 33.5 mL of deionized water, add 2.5 mL of 16 mg / mL solution. -1 A potassium persulfate solution was heated at 70°C for 24 hours under nitrogen protection, and the resulting solution was centrifuged to obtain PS seeds. 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 of 16 mg / mL solution were added. -1 Potassium persulfate solution was heated at 70°C for 24 hours under nitrogen protection, and the PS spheres were washed and centrifuged.

[0058] (2) Disperse 6.5g of PS spheres in 8mL of 70mg mL solution. -1 An ethanol solution of polyvinylpyrrolidone was stirred at room temperature for 12 hours, collected by centrifugation at 8000 rpm, washed 3-4 times with ethanol, and 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) Dissolve Co(NO3)2·6H2O (0.32 mmol) and Zn(NO3)2·6H2O (0.16 mmol) in 24 mL of methanol solution, add 0.2 mL of PS ball solution, stir at room temperature, add 50 mL of 2-methylimidazole methanol solution, 2 mg FeCl3·6H2O, 1.6 mg NiCl2·6H2O and 2 mg CuCl2·4H2O, stir to obtain a mixed solution, age at room temperature for 1.5 h, wash and dry to obtain the product;

[0060] (4) The product from step (3) was sintered at 400℃ for 2 hours, and then sintered at 750℃ for 2 hours, with a heating rate of 2℃ / min for both times. -1 Finally, the catalyst was etched with 0.5M nitric acid for 28 hours to obtain a high-entropy alloy electrocatalyst (NC-CoZnFeNiCu) supported on a hollow nanocage.

[0061] Example 5

[0062] The preparation method of the electrocatalyst of high-entropy alloy supported on hollow nanocage in this embodiment includes the following steps:

[0063] (1) Disperse 5.4 mL of styrene in 33.5 mL of deionized water, add 2.5 mL of 19 mg / mL solution. -1A potassium persulfate solution was heated at 70°C for 24 hours under nitrogen protection, and the resulting solution was centrifuged to obtain PS seeds. 4 g of PS seeds were dispersed in 33.5 mL of deionized water, and 5.4 mL of styrene and 2.5 mL of 19 mg / mL solution were added. -1 Potassium persulfate solution was heated at 70°C for 24 hours under nitrogen protection, and the PS spheres were washed and centrifuged.

[0064] (2) Disperse 5g of PS balls in 10mL of 50mg mL of water. -1 An ethanol solution of polyvinylpyrrolidone was stirred at room temperature for 12 hours, collected by centrifugation at 8000 rpm, washed 3-4 times with ethanol, and 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) Dissolve Co(NO3)2·6H2O (0.32 mmol) and Zn(NO3)2·6H2O (0.16 mmol) in 24 mL of methanol solution, add 0.6 mL of PS ball solution, stir at room temperature, add 50 mL of 2-methylimidazole methanol solution, 1.6 mg FeCl3·6H2O, 2 mg NiCl2·6H2O and 2.4 mg CuCl2·4H2O, stir to obtain a mixed solution, age at room temperature for 3 h, wash and dry to obtain the product;

[0066] (4) The product from step (3) was sintered at 300℃ for 2 hours, and then sintered at 850℃ for 2 hours, with a heating rate of 6℃ / min for both times. -1 Finally, the catalyst was etched with 2M nitric acid for 16 hours to obtain a high-entropy alloy electrocatalyst (NC-CoZnFeNiCu) supported on a hollow nanocage.

[0067] Example 6

[0068] The preparation method of the electrocatalyst of high-entropy alloy supported on hollow nanocage in this embodiment includes the following steps:

[0069] (1) Disperse 4 mL of styrene in 33.5 mL of deionized water, add 2.5 mL of 18 mg / mL solution. -1 A potassium persulfate solution was heated at 60°C for 26 hours under nitrogen protection, and the resulting solution was centrifuged to obtain PS seeds. 3g of PS seeds were dispersed in 33.5mL of deionized water, and 5.4mL of styrene and 2.5mL of 19mg / mL solution were added. -1 Potassium persulfate solution was heated at 60°C for 26 hours under nitrogen protection, and the PS spheres were washed and centrifuged.

[0070] (2) Disperse PS spheres (6.5g) in 10mL and 50mg mL.-1 An ethanol solution of polyvinylpyrrolidone was stirred at room temperature for 12 hours, collected by centrifugation at 8000 rpm, washed 3-4 times with ethanol, and 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) Dissolve Co(NO3)2·6H2O (0.32 mmol) and Zn(NO3)2·6H2O (0.32 mmol) in 20 mL of methanol solution, add 0.4 mL of PS ball solution, stir at room temperature, add 45 mL of 2-methylimidazole methanol solution, 1 mg FeCl3·6H2O, 2 mg NiCl2·6H2O and 0.8 mg CuCl2·4H2O, stir to obtain a mixed solution, age at room temperature for 2 h, wash and dry to obtain the product;

[0072] (4) The product from step (3) was sintered at 350℃ for 2 hours, and then sintered at 800℃ for 2 hours, with a heating rate of 4℃ / min for both times. -1 Finally, the catalyst was etched with 1M nitric acid for 24 hours to obtain a high-entropy alloy electrocatalyst (NC-CoZnFeNiCu) supported on a hollow nanocage.

[0073] Example 7

[0074] The preparation method of the electrocatalyst of high-entropy alloy supported on hollow nanocage in this embodiment includes the following steps:

[0075] (1) Disperse 4 mL of styrene in 33.5 mL of deionized water, add 2.5 mL of 18 mg / mL solution. -1 A potassium persulfate solution was heated at 75°C for 20 hours under nitrogen protection, and the resulting solution was centrifuged to obtain PS seeds. 3.3 g of PS seeds were dispersed in 33.5 mL of deionized water, and 4 mL of styrene and 2.5 mL of 18 mg / mL solution were added. -1 Potassium persulfate solution was heated at 75°C for 20 hours under nitrogen protection, and the PS spheres were washed and centrifuged.

[0076] (2) Disperse PS spheres (3g) in 10mL and 50mg mL. -1 An ethanol solution of polyvinylpyrrolidone was stirred at room temperature for 12 hours, centrifuged at 8000 rpm, washed 3-4 times with ethanol, and 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) Dissolve Co(NO3)2·6H2O (0.16 mmol) and Zn(NO3)2·6H2O (0.32 mmol) in 30 mL of methanol solution, add 0.4 mL of PS ball solution, stir at room temperature, add 40 mL of 2-methylimidazole methanol solution, 5 mg FeCl3·6H2O, 5 mg NiCl2·6H2O and 5 mg CuCl2·4H2O, stir to obtain a mixed solution, age at room temperature for 2 h, wash and dry to obtain the product;

[0078] (4) The product from step (3) was sintered at 350℃ for 2 hours, and then sintered at 800℃ for 2 hours, with a heating rate of 4℃ / min for both times. -1 Finally, the catalyst was etched with 1M nitric acid for 24 hours to obtain a high-entropy alloy electrocatalyst (NC-CoZnFeNiCu) supported on a hollow nanocage.

[0079] Comparative Example 1

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

[0081] (1) Disperse 4 mL of styrene in 33.5 mL of deionized water, add 2.5 mL of 18 mg / mL solution. -1 A potassium persulfate (K₂S₂O₈) solution was heated at 70°C for 24 hours under nitrogen protection. After centrifugation, PS seeds were obtained. 3g of PS seeds were dispersed in 33.5mL of deionized water, and 4mL of styrene and 2.5mL of 18mg / mL solution were added. -1 Potassium persulfate solution was heated at 70°C for 24 hours under nitrogen protection, and the PS spheres were washed and centrifuged.

[0082] (2) Disperse PS spheres (6g) in 10mL and 50mg mL of water. -1 An ethanol solution of polyvinylpyrrolidone was stirred at room temperature for 12 hours, collected by centrifugation at 8000 rpm, washed 3-4 times with ethanol, and 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) Dissolve Co(NO3)2·6H2O (0.16 mmol) and Zn(NO3)2·6H2O (0.32 mmol) in 24 mL of methanol solution, add 0.4 mL of PS ball solution, stir at room temperature, add 40 mL of 2-methylimidazole methanol solution, stir to obtain a mixed solution, age at room temperature for 1 h, wash, and dry to obtain the product;

[0084] (4) The product from step (3) was sintered at 350℃ for 2 hours, and then sintered at 800℃ for 2 hours, with a heating rate of 4℃ / min for both times. -1 Finally, the alloy electrocatalyst (NC-CoZn) was obtained by etching with 1M nitric acid for 24 hours.

[0085] Application examples

[0086] The NC-CoZnFeNiCu obtained in the examples, the NC-CoZn obtained in Comparative Example 1, and the commercially available Pt / C catalyst were used to prepare electrocatalysts for oxygen reduction reactions.

[0087] The specific steps for preparing the working electrode in the electrocatalytic oxygen reduction process are as follows: 5 mg of catalyst is dispersed in 1 mL of a 3:2 water-isopropanol solution and sonicated for 1 h to ensure uniform dispersion of the catalyst in the water-isopropanol mixture. Then, 20 μL of Nafion solution (5 wt%) is added and sonicated for 0.5 h to prepare a uniform 5 mg / mL working electrode. -1 The catalyst ink was prepared by uniformly coating 10 μL of the above catalyst ink (containing 50 μg of catalyst) onto a 5 mm diameter glassy carbon electrode.

[0088] The oxygen reduction performance of the above working electrode was tested using linear sweep voltammetry (LSV). The specific test method is as follows: In a 1M KOH solution saturated with O2, the oxygen reduction performance of the electrode was studied by linear sweep voltammetry at a rotation speed of 1600 rpm and a voltammetry time of 5 mV / s. -1 The scan rate was used for testing. Background current was subtracted from the measured current using iR correction to eliminate the influence of capacitive current. The half-wave potential of the catalyst can be obtained from the curve, allowing for comparison of the performance of different catalysts.

[0089] The linear sweep voltammetry curve of the high-entropy alloy electrocatalyst supported on hollow nanocages prepared in this invention is shown in the figure below. Figure 4 As shown in the figure, the half-wave potential of the sample prepared in Example 1 is 0.896V, and the dynamic current density is 31.88mA / cm². -2 The Pt / C catalyst exhibits a half-wave potential of 0.833 V and a dynamic current density of 3.61 mA cm⁻¹. -2 The NC-CoZn catalyst has a half-wave potential of 0.811 V and a dynamic current density of 1.01 mA cm⁻¹. -2 These values ​​are all significantly higher than the overpotential of the obtained sample. The test results show that NC-CoZnFeNiCu has superior ORR catalytic activity. The specific data of the half-wave potential and dynamic current density of the catalysts prepared in different examples and comparative examples, as well as 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 shown in Table 1, the catalysts in the examples exhibit higher dynamic current density and half-wave potential compared to Comparative Example 1 and the Pt / C catalyst, and thus have higher reaction activity and better catalytic efficiency.

[0093] The above-mentioned working electrode was subjected to an accelerated durability test to assess its oxygen reduction cycle stability. The specific test method is as follows: in a 0.1M KOH solution containing saturated O2, the electrode was rotated at 1600 rpm with a scan rate of 10 mV / s. -1 The LSV curve was measured, and then 10,000 cycles of CV (scanning rate of 100 mV / s, scanning only within the voltage range of the redox peak) were performed on the same solution. The LSV curve was then measured again under the same conditions. The stability of the catalyst was evaluated by comparing the attenuation 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 below. Figure 5 The results showed that after 10,000 CV scans, the half-wave potential decreased 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 principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an electrocatalyst of hollow nanocage loaded high-entropy alloy, characterized in that, The steps are as follows: (1) dispersing styrene in deionized water, adding potassium persulfate solution, heating and reacting under nitrogen protection, centrifuging to obtain PS seeds; dispersing the PS seeds in deionized water, adding styrene and potassium persulfate solution, heating and reacting under nitrogen protection, and washing and centrifuging the PS balls; (2) dispersing the PS balls in a polyvinylpyrrolidone ethanol solution, stirring at room temperature, centrifuging, and dispersing in a methanol solution to obtain a PS ball solution; (3) adding the PS ball solution to a methanol solution of Co(NO3)2·6H2O and Zn(NO3)2·6H2O, stirring at room temperature, then adding a 2-methylimidazole methanol solution, FeCl3·6H2O, NiCl2·6H2O, and CuCl2·4H2O, stirring to obtain a mixed solution, aging, washing, and drying to obtain the product; (4) after the product of step (3) is treated by stage calcination and concentrated acid etching, NC-CoZnFeNiCu, i.e. a hollow nanocage loaded high-entropy alloy electrocatalyst, is obtained; in the mixed solution of step (3), the mass ratio of Co(NO3)2·6H2O, Zn(NO3)2·6H2O, and FeCl3·6H2O 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).

2. The method for preparing the electrocatalyst of high-entropy alloy supported on hollow nanocages according to claim 1, characterized in that, In step (1), 8.8-11.3 mg of potassium persulfate is needed per milliliter of styrene; the mass ratio of PS seeds to styrene is (0.6-0.9):1; the heating reaction temperature is 60-75℃, and the time is 20-26 h.

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

4. The method for preparing the electrocatalyst of high-entropy alloy supported on hollow nanocages according to claim 3, characterized in that, In step (3), the concentration of the 2-methylimidazole methanol solution 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.

5. The method for preparing the electrocatalyst of high-entropy alloy supported on hollow nanocages according to claim 4, characterized in that, In 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 2-methylimidazole methanol solution is (100-150):(1-3):(200-250); the aging temperature is room temperature, and the time is 1.5-3 h.

6. The method for preparing the electrocatalyst of high-entropy alloy supported on hollow nanocages according to claim 5, characterized in that, In step (4), the stage calcination treatment refers to first heating to 300-400℃ at a heating rate of 2-6℃ / min, calcining for 1.5-3 h, then heating to 750-850℃ at a heating rate of 2-6℃ / min, and calcining for 1.5-3 h in an argon atmosphere.

7. The method for preparing the electrocatalyst of high-entropy alloy supported on hollow nanocages according to claim 6, characterized in that, In step (4), the concentrated acid etching refers to treating with 0.5-2 M nitric acid for 16-28 h.

8. An electrocatalyst of a hollow nanocage loaded high-entropy alloy prepared by the preparation method of claim 1.

9. Use of the hollow nanocage supported high-entropy alloy electrocatalyst of claim 8 in energy storage and conversion devices.

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