High-entropy alloy nano-catalyst, preparation method and application

Abstract

The invention discloses a high-entropy alloy nano-catalyst and a preparation method and application thereof.The catalyst is nano-particles with the particle size being 2-10 nm, the specific surface area of the nano-particles is 50-600 m < 2 > / g, vacancy defects are mainly distributed near Ru or Co or Ni atomic sites, raw materials of the nano-particles comprise the following metal elements of Mn, Fe, Co, Ni, Ru and M, and M is volatile metal. According to the high-entropy alloy nano-catalyst, the preparation method and the application, the high-entropy alloy nano-catalyst has rich vacancy defects, high component uniformity and excellent chemical stability, and the hydrogen evolution reaction performance can be remarkably improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of catalysis technology, and particularly relates to a high-entropy alloy nano catalyst, a preparation method and application. BACKGROUND

[0002] With the rapid development of clean energy technology, hydrogen energy as an important carrier of future green energy has attracted much attention. Water electrolysis for hydrogen production has become a key technology for hydrogen production because of its green and environmentally friendly process and high energy efficiency. The catalytic activity, structural stability and scalable preparation ability of the water electrolysis hydrogen evolution reaction (HER) catalyst directly determine its application prospect in industrialization promotion.

[0003] Although traditional noble metal (such as Pt, Ru, etc.) based catalysts have excellent performance, they are seriously restricted in large-scale application due to high cost and resource scarcity. In recent years, high-entropy alloy (HEA) catalysts have become an important research hotspot in the field of non-noble metal catalysts due to their synergistic effect of multiple components, rich active sites and excellent chemical stability.

[0004] However, most of the existing high-entropy alloy nano materials are prepared by wet routes such as co-precipitation and chemical reduction, which generally have problems such as poor material uniformity, difficulty in precise control of vacancy defects, complex process and limited scalability. Vacancy defects have been proven to effectively adjust the surface electronic structure of the catalyst and improve the performance of electrochemical reactions such as HER, but how to realize in-situ and controllable induction of vacancies in a multi-component high-entropy system is still a major technical challenge in the current field.

[0005] In addition, the structure evolution and activity mechanism of the material are highly dependent on the environmental purity and sample consistency of the preparation and characterization process. Traditional material preparation and characterization are mostly carried out in a dispersed environment, and the sample is easily contaminated during air exposure or transfer, resulting in inaccurate structure, surface state and performance characterization results, which restricts the in-depth study and efficient optimization of the intrinsic structure and performance of the material.

[0006] Therefore, in view of the above technical problems, it is necessary to provide a high-entropy alloy nano catalyst, a preparation method and application. SUMMARY

[0007] The purpose of the present application is to provide a high-entropy alloy nano catalyst, a preparation method and application.

[0008] In order to achieve the above purpose, the technical scheme provided by an embodiment of the present application is as follows:

[0009] The high-entropy alloy nano catalyst is a nanoparticle with a particle size of 2-10 nm, and the specific surface area of the nanoparticle is 50-600 m 2 / g, wherein the vacancy defects are mainly distributed near the Ru, Co or Ni atomic sites, and the raw materials of the nanoparticles include the following metal elements: Mn, Fe, Co, Ni, Ru, M, wherein M is a volatile metal.

[0010] In one or more embodiments of the present invention, vacancy defects are induced by volatile metal M at high temperature.

[0011] In one or more embodiments of the present invention, the volatile metal is selected from Zn, Cd or Mg.

[0012] In one or more embodiments of the present invention, a method for preparing a high entropy alloy nanocatalyst comprises the following steps:

[0013] A mixed solvent formed by mixing deionized water and an organic solvent is prepared, and then an organic ligand and a metal source are added. After stirring to obtain a uniform solution, an auxiliary agent is added (after a uniform solution is formed), reflux reaction is carried out, and cooling is performed to obtain a first product;

[0014] Prepare a Tris-HCl buffer solution containing dopamine hydrochloride, add the buffer solution dropwise to the stirred first product, stir the reaction, remove impurities, and dry to obtain a second product;

[0015] The second product is heated to 800-1000° C. (preferably, 880-920° C.) under a protective atmosphere, kept warm, and cooled to obtain a catalyst.

[0016] In one or more embodiments of the present invention, the auxiliary agent is selected from: melamine, urea, and ethanolamine.

[0017] In one or more embodiments of the present invention, the volume ratio of deionized water to the organic solvent in the mixed solvent is 1:3. Preferably, the organic solvent is selected from DMF, NMP, and DMSO.

[0018] In one or more embodiments of the present invention, the organic ligand is selected from: 2-aminoterephthalic acid.

[0019] In one or more embodiments of the present invention, the metal source is a chloride or nitrate, wherein the metal elements include Mn, Fe, Co, Ni, Ru, and M; and the molar ratio of the metal atoms in each metal raw material satisfies: Mn:Fe:Co:Ni:Ru:M= a:b:c:d:e:f, and a+b+c+d+e+f=1, and 1 / 12≤a≤1 / 3, 1 / 12≤b≤1 / 3, 1 / 12≤c≤1 / 3, 1 / 12≤d≤1 / 3, 1 / 12≤e≤1 / 3, and 1 / 12≤f≤1 / 3. Preferably, the metal atoms in each metal raw material of the metal source are in equal molar ratios.

[0020] In one or more embodiments of the present application, the protective atmosphere is an inert gas or a mixture of inert gas and hydrogen. Further preferably, the inert gas is selected from nitrogen, helium, argon. Further preferably, the volume fraction of hydrogen in the mixture is 1-20 vol%. More preferably, 2-10 vol%; more preferably, 3-7 vol%.

[0021] In one or more embodiments of the present application, the temperature is raised at a rate of 2-10℃ / min -1 Heating. Preferably, the temperature is raised at a rate of 5℃ / min -1 .

[0022] In one or more embodiments of the present application, the holding time is 1-5 hours, so that the M element is selectively volatilized and induced to form vacancy defects. Preferably, zinc. Preferably, the holding time is 3 hours.

[0023] In one or more embodiments of the present application, the preparation method of high-entropy alloy nanocatalyst is implemented on a vacuum interconnection platform, so that the whole process of preparation-transferring-characterization is realized without air exposure.

[0024] In one or more embodiments of the present application, the high-entropy alloy nanocatalyst is applied in electrocatalytic reactions. The electrocatalytic reactions include water electrolysis, hydrogen evolution, oxygen evolution, O2 reduction, etc. In the alkaline water electrolysis hydrogen evolution reaction, the overpotential is less than 30 mV at a current density of 10 mA cm -2 The overpotential is less than 30 mV at a current density of 10 mA cm -2 1000 hours (1.0 M KOH, 25±2℃, without iR correction), showing excellent electrocatalytic activity and durability.

[0025] Compared with the prior art, the high-entropy alloy nanocatalyst, preparation method and application of the present application have rich vacancy defects, high component uniformity and excellent chemical stability, which can significantly improve the hydrogen evolution reaction performance. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0027] Figure 1 is a preparation flowchart according to an embodiment of the present application;

[0028] Figure 2is a SEM image of the precursor (a) MnFeRuCoNiZn-MOF and (b) MnFeRuCoNi-MOF according to an embodiment of the present application;

[0029] Figure 3 is a SEM-EDX image of the elemental distribution of the precursor MnFeRuCoNiZn-MOF according to an embodiment of the present application;

[0030] Figure 4 is a SEM-EDX image of the elemental distribution of the precursor MnFeRuCoNi-MOF according to an embodiment of the present application;

[0031] Figure 5 is a TEM-EDX image of the elemental distribution of the precursor MnFeRuCoNiZn-MOF according to an embodiment of the present application;

[0032] Figure 6 is a TEM-EDX image of the elemental distribution of the precursor MnFeRuCoNi-MOF according to an embodiment of the present application;

[0033] Figure 7 is a TEM image of the final product (a) MnFeRuCoNi-ZV and (b) MnFeRuCoNi according to an embodiment of the present application;

[0034] Figure 8 is a particle size histogram of the final product (a) MnFeRuCoNi-ZV and (b) MnFeRuCoNi according to an embodiment of the present application;

[0035] Figure 9 is a TEM-EDX image of the elemental distribution of the precursor MnFeRuCoNi-ZV according to an embodiment of the present application;

[0036] Figure 10 is a TEM-EDX image of the elemental distribution of the precursor MnFeRuCoNi according to an embodiment of the present application;

[0037] Figure 11 is an X-ray diffraction (XRD) pattern of the final product MnFeRuCoNi-ZV and MnFeRuCoNi according to an embodiment of the present application;

[0038] Figure 12 is a positron annihilation (PALS) plot of the final product (a) MnFeRuCoNi-ZV and (b) MnFeRuCoNi according to an embodiment of the present application;

[0039] Figure 131 is an electron spin resonance (EPR) image of the final products MnFeRuCoNi-ZV and MnFeRuCoNi according to one embodiment of the present invention;

[0040] Figure 14 The Zn volatilization pattern of MnFeRuCoNiZn-MOF according to one embodiment of the present invention is detected using near-ambient pressure X-ray photoelectron spectroscopy;

[0041] Figure 15 The catalytic HER (a) activity diagram and (b) Tafel diagram of the final products MnFeRuCoNi-ZV and MnFeRuCoNi according to one embodiment of the present invention;

[0042] Figure 16 is the 10 mA cm of the final product MnFeRuCoNi-ZV according to one embodiment of the present invention. -2 Stability diagram at current density for 30 hours;

[0043] Figure 17 is the 100 mA cm of the final product MnFeRuCoNi-ZV according to one embodiment of the present invention. -2 Stability diagram for 1080 hours at current density;

[0044] Figure 18 is the 100 mA cm of the final product MnFeRuCoNi-ZV according to one embodiment of the present invention. -2 (a) Activity comparison graph and (b) Tafel comparison graph of the activity after 24 h and the initial activity at the current density;

[0045] Figure 19 is the 100 mA cm of the final product MnFeRuCoNi-ZV according to one embodiment of the present invention. -2 TEM element distribution and particle size statistics after 24 hours at current density;

[0046] Figure 20 is the 100 mA cm of the final product MnFeRuCoNi-ZV according to one embodiment of the present invention. -2 XRD pattern after 24 h at current density;

[0047] Figure 21 According to one embodiment of the present invention, the water pressure is 5 × 10 -4 NAP-XPS spectra of MnFeRuCoNi-ZV and MnFeRuCoNi at mbar;

[0048] Figure 22is an REELS spectrum of electrochemical treatment and immersion of the final product MnFeRuCoNi-ZV according to an embodiment of the application;

[0049] Figure 23 is a TOF-SIMS spectrum of electrochemical treatment and immersion of the final product MnFeRuCoNi-ZV according to an embodiment of the application;

[0050] Figure 24 is an REELS spectrum of electrochemical treatment and immersion of the final product MnFeRuCoNi according to an embodiment of the application;

[0051] Figure 25 is a TOF-SIMS spectrum of electrochemical treatment and immersion of the final product MnFeRuCoNi according to an embodiment of the application;

[0052] Figure 26 is a performance graph of catalytic oxygen reduction reaction (ORR) of the final product MnFeRuCoNi-ZV according to an embodiment of the application;

[0053] Figure 27 is a performance graph of catalytic oxygen evolution reaction (OER) of the final product MnFeRuCoNi-ZV according to an embodiment of the application. DETAILED DESCRIPTION

[0054] In order to enable persons skilled in the art to better understand the technical solutions in the present disclosure, the technical solutions in the present disclosure will be clearly and completely described below in combination with the disclosed embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present disclosure, but not all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by persons skilled in the art without creative labor should fall within the protection scope of the present disclosure.

[0055] The present application aims to solve the problems of high-entropy alloy nanocatalysts in terms of vacancy defect construction, material uniformity, controllability, accurate characterization and industrial scalability, etc. By relying on a vacuum interconnection platform, a preparation and multi-modal characterization method of high-entropy alloy nanocatalysts induced by volatile components is provided. The method realizes the whole process of catalyst preparation in environmental protection, seamless transfer and in-situ / quasi-in-situ structure analysis, and provides a new technology for material intrinsic structure-property relationship research and large-scale application of high-performance catalysts.

[0056] The preparation method of the high-entropy alloy nanocatalyst of the present application can specifically include the following steps:

[0057] 1. 2-amino terephthalic acid (NH2-BDC) as an organic ligand, a variety of metal salts (including Mn, Fe, Co, Ni, Ru and Zn, etc.) as a metal source, N, N-dimethylformamide (DMF) and deionized water as a solvent, stirring to prepare a uniform solution at room temperature;

[0058] 2. A plurality of steps of adding metal salts in sequence, stirring and dissolving, and adding melamine are adopted to ensure uniform distribution of metal ions and form a stable precursor solution;

[0059] 3. A reflux reaction (80-90 ℃) is adopted to promote uniform coordination of multiple components and nucleation and growth of the precursor;

[0060] 4. A Tris-HCl buffer solution with a specific pH value (8.5-8.8) is prepared, dopamine hydrochloride is fully dissolved in the buffer solution, and then the dopamine hydrochloride is slowly introduced into the precursor solution to promote in-situ polymerization of dopamine and further improve the dispersion and stability of the precursor;

[0061] 5. High-speed centrifugation, multi-step ethanol washing and mild vacuum drying are adopted to remove impurities and solvent residues to the maximum extent to obtain a high-purity precursor solid;

[0062] 6. The precursor is heated to 800-1000 ℃ at a heating rate of 2-10 ℃ min-1 under the protection of argon, nitrogen or argon / hydrogen mixed gas (flow rate 100-200 mL min-1) for 15 hours, in which process, volatile components such as Zn are selectively volatilized, and vacancy defects are induced in-situ, giving consideration to high component uniformity and particle size control;

[0063] 7. The product is naturally cooled and collected to obtain a high-entropy alloy nano-catalyst with vacancy defects;

[0064] 8. Relying on a vacuum interconnection platform, the prepared catalyst is seamlessly transferred to a variety of analysis equipment to carry out multi-modal in-situ / quasi-in-situ structure and component characterization such as near ambient X-ray photoelectron spectroscopy (NAP-XPS), reflection electron energy loss spectrum (REELS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), wide-angle X-ray scattering (WAXS), etc., to systematically reveal the relationship between material structure, vacancy distribution and performance.

[0065] Example 1:

[0066] The preparation of the high-entropy alloy nano-catalyst in this example is shown in Figure 1 , which shows a preparation schematic diagram:

[0067] Raw material dissolution and mixing: 2.0 mmol of 2-amino terephthalic acid (NH2-BDC) was weighed and dissolved in a mixed solution of 36 mL of N,N-dimethylformamide (DMF) and 12 mL of deionized water, and stirred at room temperature (20-30 °C) for 30 minutes to form a uniform and clear solution.

[0068] Sequential addition of metal salts: 0.12 mmol of MnCl2·4H2O, FeCl3·6H2O, CoCl2·6H2O, NiCl2·6H2O, RuCl3, and ZnCl2 were weighed and added to the above solution one by one, and stirred for 10 minutes after each addition to ensure complete dissolution and uniform dispersion.

[0069] Addition of auxiliary agent: 1.0 g of melamine was added to the above mixed solution, and stirred at room temperature until completely dissolved.

[0070] Refiux reaction: The resulting mixed solution was transferred to a 250 mL round-bottom flask, and a reflux device was installed. The flask was heated in an oil bath at 80-90 °C for 4 hours of reflux reaction, and the stirring speed was maintained at 300 rpm during the reaction. After the reaction was completed, it was naturally cooled to 25-30 °C.

[0071] Buffer and dopamine dissolution: 5 mmol of tris(hydroxymethyl)aminomethane (Tris) was weighed and dissolved in 50 mL of deionized water. 15 mL of 0.1 mol L -1 Hydrochloric acid was added, and after stirring, deionized water was added to 100 mL. The total pH was adjusted to 8.7. 600 mg of dopamine hydrochloride was weighed and added to the Tris-HCl buffer solution, and stirred at room temperature for 7 minutes until completely dissolved.

[0072] Dropwise addition and secondary polymerization reaction: The prepared dopamine buffer solution was added dropwise to the mixed solution cooled to room temperature after refluxing under stirring for 10 minutes. After dropwise addition, it was stirred at room temperature for 24 hours to allow in-situ polymerization of dopamine, and an organic-inorganic hybrid precursor was obtained.

[0073] Solid separation and drying: The reaction system was centrifuged at 12,000 rpm for 7 minutes, the precipitate was collected, washed with ethanol three times, and dried at 60 °C for 8 hours in a vacuum to obtain the precursor solid. As shown in FIG. 2, the SEM images of the precursor MnFeRuCoNiZn-MOF and MnFeRuCoNi-MOF are shown in the figure, and the particle size is 30-60 nm. As shown in FIG. 3, the SEM element distribution of the precursor MnFeRuCoNiZn-MOF is shown in the figure, and various elements are uniformly distributed. As shown in FIG. 4, the SEM element distribution of the precursor MnFeRuCoNi-MOF is shown in the figure, and various elements are uniformly distributed. As shown in FIG. 5, the TEM element distribution of the precursor MnFeRuCoNiZn-MOF is shown in the figure, and various elements are uniformly distributed. As shown in FIG. 6, the TEM element distribution of the precursor MnFeRuCoNi-MOF is shown in the figure, and various elements are uniformly distributed. As shown in FIG. Figure 7 As shown in FIG. 8, the TEM morphology of the final product MnFeRuCoNi-ZV and MnFeRuCoNi is shown in the figure, and the particle size is mainly less than 5 nm. The detailed distribution statistics of the particle size are shown in FIG. 9. As shown in FIG. 10, the TEM element distribution of the final product MnFeRuCoNi-ZV is shown in the figure, and various elements are uniformly distributed, and the Zn element has no clear particle outline. As shown in FIG. 11, the TEM element distribution of the final product MnFeRuCoNi is shown in the figure, and various elements are uniformly distributed. As shown in FIG. 12, the XRD pattern of the final product MnFeRuCoNi-ZV and MnFeRuCoNi is shown in the figure, and the typical FCC face-centered cubic structure does not appear other impurity peaks, indicating that the product is successfully prepared. Figure 8

[0074] Vacuum interconnection platform transfer and high-temperature annealing induced vacancies: In the air-free exposure environment of the vacuum interconnection platform, the dried precursor was transferred to a quartz boat and placed in a tube furnace, and 120 mL min -1 argon was introduced at 5 °C min -1 ​annealing, Zn volatilization at high temperature induces vacancy defects, after reaction, cooling down to room temperature with furnace, the obtained product is the final product of vacancy high-entropy alloy nanocatalyst. As shown in 12, the positron annihilation lifetime spectroscopy (PALS) of the final product MnFeRuCoNi-ZV and MnFeRuCoNi is shown in the figure, the first annihilation time (328 ps) of MnFeRuCoNi-ZV is greater than that (314 ps) of MnFeRuCoNi, indicating that Zn volatilization induces more atomic-level defects in MnFeRuCoNi-ZV. As shown in 13, the electron paramagnetic resonance (EPR) of the final product MnFeRuCoNi-ZV and MnFeRuCoNi is shown in the figure, MnFeRuCoNi-ZV shows a stronger signal peak than MnFeRuCoNi, indicating that Zn volatilization induces more defects in MnFeRuCoNi-ZV. As shown in 14, the intensity change of Zn element during in-situ heating of the precursor MnFeRuCoNiZn-MOF is shown in the figure, the temperature is from 300, 400, 500, 600, 700, 750 degrees, and each temperature platform is kept for 5 minutes, the test cavity pressure is 0.0001 mbar, at 750 degrees, the signal background intensity color of Zn has no obvious difference with the background color, indicating that the content of Zn element is lower than the detection limit.

[0075] Vacuum interconnection platform multi-modal linkage characterization: relying on the vacuum interconnection platform, the prepared catalyst is seamlessly transferred to various characterization equipment, including but not limited to NAP-XPS, REELS, TOF-SIMS, XPS, WAXS, etc., in-situ / quasi-in-situ multi-modal structure and composition analysis is carried out, the vacancy type, distribution and composition uniformity are systematically analyzed, and the HER performance is evaluated in combination with electrochemical test, 10 mA cm -2 overpotential is lower than 30 mV, 100 mA cm -2 stable operation for more than 1000 hours, as shown in 15, the activity and Tafel plots of the final product MnFeRuCoNi-ZV and MnFeRuCoNi are shown in the figure, at 10 mA cm -2 current density, the overpotential (7 mV) of MnFeRuCoNi-ZV is lower than that (26 mV) of MnFeRuCoNi, indicating that the activity of MnFeRuCoNi-ZV is better than that of MnFeRuCoNi; the Tafel slope (51 mV dec -1 ) of MnFeRuCoNi-ZV is lower than that (93 mV dec -1) is lower, indicating that MnFeRuCoNi-ZV has faster reaction kinetics than MnFeRuCoNi. As shown in 16, the figure shows the final product MnFeRuCoNi-ZV at 10 mA cm -2 The stability diagram of the final product MnFeRuCoNi-ZV at 100 mA cm is shown in Figure 17. -2 The stability diagram of the final product MnFeRuCoNi-ZV at 100 mA cm is shown in Figure 18. -2 The activity comparison before and after the 24-hour current density stability test shows that the LSV curves of MnFeRuCoNi-ZV are almost the same before and after 24 hours, and the Tafel slope is almost unchanged, indicating the excellent stability of MnFeRuCoNi-ZV. As shown in Figure 19, the figure shows the final product MnFeRuCoNi-ZV at 100 mA cm -2 TEM element distribution and particle size statistics before and after 24 hours of current density stability test. After 24 hours, the elements are evenly distributed and the particle size is still mainly below 5 nm, indicating that the material has not agglomerated. As shown in 20, the figure shows the final product MnFeRuCoNi-ZV at 100 mA cm -2XRD patterns of the current density before and after 24 hours stability test, after 24 hours, the main diffraction peaks remain consistent, and no other impurity peaks appear, indicating that the material phase remains consistent. As shown in 21, the NAP-XPS spectrum of the final product MnFeRuCoNi-ZV and MnFeRuCoNi is shown in the figure, the area ratio of hydroxyl oxygen peak to lattice oxygen peak of MnFeRuCoNi-ZV (1.83) is greater than that of MnFeRuCoNi (1.27), indicating that MnFeRuCoNi-ZV has stronger hydrolysis capacity than MnFeRuCoNi. As shown in 22, the REELS spectrum of the final product MnFeRuCoNi-ZV is shown in the figure, as shown in 24, the REELS spectrum of the final product MnFeRuCoNi-ZV is shown in the figure, and the MnFeRuCoNi-ZV after electrochemical treatment and immersion shows stronger H loss peak increase than MnFeRuCoNi, which further indicates that MnFeRuCoNi-ZV has stronger hydrolysis capacity than MnFeRuCoNi. As shown in 23, the TOF-SIMS spectrum of the final product MnFeRuCoNi-ZV is shown in the figure, as shown in 25, the TOF-SIMS spectrum of the final product MnFeRuCoNi-ZV is shown in the figure, and the MnFeRuCoNi-ZV after electrochemical treatment and immersion shows stronger H3O + peak increase than MnFeRuCoNi, which further indicates that MnFeRuCoNi-ZV has stronger hydrolysis capacity than MnFeRuCoNi.

[0076] Example Group 2:

[0077] The difference between each embodiment of this group and Example 1 is only:

[0078] (A) Remove RuCl3:

[0079] Example A-1 (equal amount of supplement): The molar amount of the original Ru is equally divided into Mn / Fe / Co / Ni / Zn. After adjustment, the amount of MnCl2·4H2O, FeCl3·6H2O, CoCl2·6H2O, NiCl2·6H2O and ZnCl2 is 0.144 mmol.

[0080] The sample in 1 M KOH is 10 mA cm -2 The overpotential is lower than 230 mV, and the current density is 100 mA cm -2 The stable operation is more than 100 hours.

[0081] Example A-2 (Zn-enriched): The amount of MnCl2*4H2O, FeCl3*6H2O, CoCl2*6H2O, NiCl2*6H2O was kept at 0.12 mmol, the amount of ZnCl2 was adjusted to 0.24 mmol.

[0082] Sample at 10 mA cm in 1 M KOH -2 Overpotential below 200 mV at 100 mA cm -2 Stable operation below for more than 100 hours.

[0083] Example A-3 (transition metal supplementation): The amount of MnCl2*4H2O, FeCl3*6H2O, CoCl2*6H2O, NiCl2*6H2O was adjusted to 0.15 mmol each, the amount of ZnCl2 was kept at 0.12 mmol.

[0084] Sample at 10 mA cm in 1 M KOH -2 Overpotential below 250 mV at 100 mA cm -2 Stable operation below for more than 100 hours.

[0085] (B) Replacement of ZnCl2 by CdCl2 or MgCl2:

[0086] Example B-1 (equal replacement): ZnCl2 was replaced by CdCl2 in equal amounts, i.e. the amount of CdCl2 was 0.12 mmol;

[0087] Sample at 10 mA cm in 1 M KOH -2 Overpotential below 240 mV at 100 mA cm -2 Stable operation below for more than 100 hours.

[0088] Example B-2 (enrichment of volatile components): ZnCl2 was replaced by MgCl2, the amount of MgCl2 was 0.18 mmol (1.5 x 0.12);

[0089] Sample at 10 mA cm in 1 M KOH -2 Overpotential below 280 mV at 100 mA cm -2 Stable operation below for more than 100 hours.

[0090] Example B-3 (weak volatile components): ZnCl2 was replaced by CdCl2, the amount of CdCl2 was 0.08 mmol (0.67 x 0.12).

[0091] Sample at 10 mA cm in 1 M KOH -2 Overpotential below 270 mV at 100 mA cm-2 Stable operation below 100 hours.

[0092] Example Set 3: Annealing Temperature / Atmosphere Variations

[0093] The only difference between the examples in this set and Example 1 is:

[0094] (C): Adjusting Annealing Temperature

[0095] Example C-1 : Annealing at 800 °C for 3 hours.

[0096] Sample at 10 mA cm in 1 M KOH -2 Overpotential below 180 mV at 100 mA cm -2 Stable operation below 300 hours.

[0097] Example C-2: Annealing at 1000 °C for 3 hours.

[0098] Sample at 10 mA cm in 1 M KOH -2 Overpotential below 30 mV at 100 mA cm -2 Stable operation below 1200 hours.

[0099] (D): Adjusting Protective Atmosphere

[0100] Example D-1 : 100 mL min -1 Argon.

[0101] Sample at 10 mA cm in 1 M KOH -2 Overpotential below 30 mV at 100 mA cm -2 Stable operation below 1000 hours.

[0102] Example D-2: 200 mL min -1 Argon.

[0103] Sample at 10 mA cm in 1 M KOH -2 Overpotential below 30 mV at 100 mA cm -2 Stable operation below 1000 hours.

[0104] Example D-3: Argon replaced with a mixture of argon and hydrogen, where the hydrogen volume fraction is 1 vol%.

[0105] Sample at 10 mA cm in 1 M KOH -2 Overpotential below 40 mV at 100 mA cm -2 Stable operation below 800 hours.

[0106] Example D-4: Argon is replaced by a mixture of argon and hydrogen, where the volume fraction of hydrogen is 10 vol%.

[0107] The sample is 10 mA cm -2 The overpotential is below 35 mV at 100 mA cm -2 The stable operation is more than 800 hours.

[0108] Example D-5: Argon is replaced by a mixture of argon and hydrogen, where the volume fraction of hydrogen is 20 vol%.

[0109] The sample is 10 mA cm -2 The overpotential is below 50 mV at 100 mA cm -2 The stable operation is more than 800 hours.

[0110] Example D-6: Argon is replaced by a mixture of nitrogen and hydrogen, where the volume fraction of hydrogen is 20 vol%.

[0111] The sample is 10 mA cm -2 The overpotential is below 80 mV at 100 mA cm -2 The stable operation is more than 600 hours.

[0112] The results show that the argon condition at 1000°C is the best.

[0113] Example group 4: Zn molar amount control

[0114] The difference between each example in this group and Example 1 is only:

[0115] Example E-1: The amount of ZnCl2 is adjusted to 0.06 mmol.

[0116] The sample is 10 mA cm -2 The overpotential is below 50 mV at 100 mA cm -2 The stable operation is more than 700 hours.

[0117] Example E-2: The amount of ZnCl2 is adjusted to 0.18 mmol.

[0118] The sample is 10 mA cm -2 The overpotential is below 40 mV at 100 mA cm -2 The stable operation is more than 800 hours.

[0119] Too low or too high Zn content will affect the performance, and 0.12 mmol is the best.

[0120] Example Set 5: Adjuvant instead of melamine

[0121] The difference between the examples of this set and Example 1 is only:

[0122] Example F-1 : Replacement of melamine by equivalent amount of urea etc.

[0123] Sample 10 mA cm in 1 M KOH -2 Overpotential below 100 mV, 100 mA cm -2 Stable operation below 600 hours.

[0124] Example F-2: Replacement of melamine by equivalent amount of ethanolamine etc.

[0125] Sample 10 mA cm in 1 M KOH -2 Overpotential below 90 mV, 100 mA cm -2 Stable operation below 500 hours.

[0126] Material dispersion and catalytic performance are best with melamine adjuvant.

[0127] Example Set 6: Raw material / process versatility

[0128] The difference between the examples of this set and Example 1 is only:

[0129] G: Adjustment of metal salt type

[0130] G-1 : Replacement of chloride by equivalent amount of nitrate.

[0131] Sample 10 mA cm in 1 M KOH -2 Overpotential below 50 mV, 100 mA cm -2 Stable operation below 900 hours.

[0132] G-2: Replacement of chloride by equivalent amount of acetate.

[0133] Sample 10 mA cm in 1 M KOH -2 Overpotential below 80 mV, 100 mA cm -2 Stable operation below 800 hours.

[0134] H: Adjustment of organic solvent

[0135] H-1 : Replacement of DMF by equivalent amount of NMP.

[0136] Sample 10 mA cm in 1 M KOH -2 Overpotential below 40 mV, 100 mA cm -2 Stable operation below 1000 hours.

[0137] H-2: Replace DMF with equal amount of DMSO.

[0138] Sample 10 mA cm in 1 M KOH -2 Overpotential below 40 mV, 100 mA cm -2 Stable operation below 900 hours.

[0139] Different solvent systems can tune alloy homogeneity and vacancy distribution.

[0140] Comparative Example 1: Comparison of Zn-induced vacancy effectiveness

[0141] The only difference between this comparative example and Example 1 is that no ZnCl2 was added.

[0142] Sample 10 mA cm in 1 M KOH -2 Overpotential below 400 mV, 100 mA cm -2 Stable operation below 1100 hours.

[0143] Example 7: Ball-milling / batch approach

[0144] The only difference between this example and Example 1 is that the feed was scaled up by a factor of ten, and all parameters were scaled proportionally, and the batch-prepared product performed consistently.

[0145] Example Set 8: Multiple application scenarios

[0146] The resulting catalyst is not only suitable for HER, but also performs excellently in catalytic reactions such as oxygen reduction reaction, oxygen evolution reaction, etc. As shown in 26, the graph shows the catalytic oxygen reduction performance of the final product MnFeRuCoNi-ZV, indicating that MnFeRuCoNi-ZV also has good catalytic ORR performance. As shown in 27, the graph shows the catalytic oxygen evolution performance of the final product MnFeRuCoNi-ZV, indicating that MnFeRuCoNi-ZV also has good catalytic OER performance. The platformization process is convenient for multi-purpose promotion.

[0147] It is apparent to those skilled in the art that the present disclosure is not limited to the details of the foregoing exemplary embodiments, and that the present disclosure can be implemented in other particular forms without departing from the spirit or essential characteristics of the present disclosure. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, and the scope of the present disclosure should be defined by the appended claims rather than the above description, and it is intended to encompass all changes falling within the meaning and range of equivalents of the elements of the claims. Any reference signs in the claims should not be considered as limiting the claims involved.

[0148] Furthermore, it should be understood that although the specification is described in terms of embodiments, not every embodiment includes every feature or implementation described herein. The specification can include implicit combinations of explicitly mentioned features and / or implicit combinations of implicitly mentioned features. Such combinations are also expressly included within the scope of the specification and an embodiment.

Claims

1. A high entropy alloy nanocatalyst, which is a nanoparticle with a particle size of 2-10 nm and a specific surface area of ​​50-600 m 2 / g, wherein the vacancy defects are mainly distributed near the Ru, Co or Ni atomic sites, and the raw materials of the nanoparticles include the following metal elements: Mn, Fe, Co, Ni, Ru, M, wherein M is a volatile metal.

2. The high entropy alloy nanocatalyst according to claim 1, characterized in that The vacancy defects are generated by volatile metal M under high temperature induction.

3. The high entropy alloy nanocatalyst according to claim 1, characterized in that The volatile metal M is selected from Zn, Cd or Mg.

4. The method for preparing a high entropy alloy nanocatalyst according to any one of claims 1 to 3, characterized in that: The steps include: A mixed solvent formed by mixing deionized water and an organic solvent is prepared, and then an organic ligand and a metal source are added. After stirring to obtain a uniform solution, an auxiliary agent is added, the mixture is refluxed, and the mixture is cooled to obtain a first product. Prepare a Tris-HCl buffer solution containing dopamine hydrochloride, add the buffer solution dropwise to the stirred first product, stir the reaction, remove impurities, and dry to obtain a second product; The second product is heated to 800-1000° C. under a protective atmosphere, kept warm, and cooled to obtain a catalyst.

5. The method for preparing a high entropy alloy nanocatalyst according to claim 4, wherein: The volume ratio of deionized water to the organic solvent in the mixed solvent is 1:

3.

6. The method for preparing a high entropy alloy nanocatalyst according to claim 4, wherein: The organic ligand is selected from: 2-aminoterephthalic acid.

7. The method for preparing a high entropy alloy nanocatalyst according to claim 4, wherein: The metal source is a chloride, a nitrate, or an acetate, wherein the metal elements include Mn, Fe, Co, Ni, Ru, and M; and the molar ratio of the metal atoms in each metal raw material satisfies: Mn:Fe:Co:Ni:Ru:M= a:b:c:d:e:f, and simultaneously satisfies a+b+c+d+e+f=1, and 1 / 12≤a≤1 / 3, 1 / 12≤b≤1 / 3, 1 / 12≤c≤1 / 3, 1 / 12≤d≤1 / 3, 1 / 12≤e≤1 / 3, and 1 / 12≤f≤1 / 3.

8. The method for preparing a high entropy alloy nanocatalyst according to claim 7, wherein: The protective atmosphere is an inert gas or a mixture of an inert gas and hydrogen.

9. The method for preparing a high entropy alloy nanocatalyst according to claim 4, wherein: The heating rate is 2-10°C min -1 heating.

10. Use of the high entropy alloy nanocatalyst according to any one of claims 1 to 3 in an electrocatalytic reaction.

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