Intermetallic compound nanocrystalline electro-catalytic material and preparation method thereof

Abstract

The invention discloses an intermetallic compound nanocrystalline electro-catalytic material and a preparation method thereof, and relates to the technical field of electro-catalytic materials.The method comprises the following steps that nickel salt and ferric salt are mixed to obtain mixed metal salt; then uniformly mixing the mixed metal salt with carbon black, adding deionized water, and carrying out ultrasonic dispersion to obtain a precursor solution; freeze-drying the precursor solution; the precursor powder is continuously smeared on a flexible base material, the flexible base material is fed into a reaction chamber through a roller flow device to be subjected to radiation heating, atoms are diffused and rearranged, and nickel species and iron species are migrated and assembled into the intermetallic compound. The invention further discloses the intermetallic compound nanocrystalline electro-catalytic material prepared by the method and application of the intermetallic compound nanocrystalline electro-catalytic material. The ordered L12-Ni3Fe electro-catalytic material is synthesized through an ultrafast radiation heating method, meanwhile, the advantages of high-flux production and environmental protection are achieved, and the electro-catalytic material is excellent in performance and has high application value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrocatalytic materials, and particularly relates to an intermetallic compound nanocrystal electrocatalytic material and a preparation method thereof. BACKGROUND

[0002] Intermetallic nanocrystals (INCs), such as L10-PtFe, Pd3Pb, Pt3Co and fct-FePd binary INCs for oxygen reduction (ORR), L10-FeMnPt, L10-PtCuPdAgFe for hydrogen evolution (HER), L10-PtSnBi, L10-(PtPdIrRu)2FeCu for formic acid oxidation (FAOR), L12-PtRhFe, L10-PtPdCuGa and L10-PtRhBiSnSb for methanol oxidation (MOR), are important frontiers in catalysis and are crucial for driving a sustainable global economy. In theory, the precise atomic arrangement in these materials can achieve significant catalytic performance, and compared with disordered materials, the mass activity can be increased by 1-5 orders of magnitude or even more. However, a huge challenge has hindered their wide application: the lack of scalable and sustainable synthesis routes. This bottleneck is due to a fundamental problem in material synthesis. Although traditional high-temperature annealing (usually 600-1000°C for several hours) provides the necessary activation energy for atomic ordering, it can cause irreversible sintering due to the lack of effective kinetic regulation. This destructive process can cause the original nanoparticles (<10 nm) to coarsen into bulk structures (>50 nm), resulting in a large loss of more than 90% of the active surface area and reducing the catalytic performance of intermetallic nanocrystals. For a long time, it has been difficult to mass-produce intermetallic nanocrystals with precise structures without precise regulation, which is a major obstacle to the transition of intermetallic nanocrystals from the laboratory to the next generation of economic energy technology.

[0003] The prior art is mainly based on thermal annealing, such as the preparation of binary RhFe INCs by Wang et al. using thermal annealing. However, thermal annealing has typical disadvantages: long time and high temperature. Generally, the power of a tubular furnace is about 1200 W, and long-time operation not only makes the preparation of materials inefficient but also consumes a large amount of energy. In addition, although high temperature can promote the ordered arrangement of atoms, long-time high-temperature reaction can easily cause sintering and particle agglomeration, resulting in an increase in particle size. In the above method, although the synthesized RhFe INCs have a small particle size, the degree of order is only 66.3%.

[0004] In addition, researchers have successfully synthesized ternary PtSnBi INCs using a wet chemical method. Although the wet chemical method can achieve the controllable synthesis of intermetallic compound nanocrystals with different morphologies, thereby preparing catalysts with specific high-activity crystal faces and uniform nanocrystal sizes, the synthesis process has complex kinetic and thermodynamic problems, which not only leads to poor reproducibility of the product, but also brings challenges to large-scale production. In addition, the wet chemical method has limitations in preparing intermetallic compound nanocrystals containing strongly immiscible elements, which often causes phase separation; and the wet chemical method inevitably uses a large amount of organic solvents, and the volatilization of a large amount of organic matter during the reaction process will irreversibly damage the atmospheric environment.

[0005] Therefore, it is urgent to develop a new preparation method to solve the problems of the existing intermetallic compound nanocrystal catalysts as electrocatalysts, such as difficult ordered structure regulation, difficult trade-off between particle size and order degree, poor catalytic performance, and harsh preparation conditions.

[0006] The present application provides a brand new high-strength ultrafast radiation heating process (URH), which uses an expandable stage engineering strategy to fundamentally bypass the above-mentioned synthesis paradox. The traditional method relies on high-temperature synthesis and annealing, which usually leads to irreversible sintering and disordering, while the strategy of the present application uses an in-situ phase transformation approach designed precisely. Taking L12-Ni3Fe INCs as an example, first, metastable Ni@Fe core-shell nanoparticles are synthesized as precursors, and under strict control of the reaction conditions, they are accurately regulated to transform into thermodynamically stable L12 phase. This method establishes a generalizable paradigm for the synthesis of intermetallic nanocrystal structures, which can be extended to other systems, such as binary, ternary, and even multi-component intermetallic compound nanocrystals. SUMMARY

[0007] To solve the above technical problems, the purpose of the present application is to provide an intermetallic compound nanocrystal electrocatalytic material (L12-Ni3Fe) and a preparation method thereof. The present application synthesizes ordered L12-Ni3Fe electrocatalytic material by ultrafast radiation heating (URH) method, which has the advantages of high-throughput production and environmental protection. The electrocatalytic material has excellent performance and great application value.

[0008] The technical scheme for solving the above technical problems is as follows: a preparation method of an intermetallic compound nanocrystal electrocatalytic material is provided, which comprises the following steps: (1) mixing nickel salt and iron salt to obtain mixed metal salt; then mixing the mixed metal salt with carbon black uniformly, adding deionized water for ultrasonic dispersion to obtain a precursor solution; (2) freeze-drying the precursor solution obtained in step (1) to obtain a precursor powder; continuously coating the precursor powder on a flexible substrate and sending the precursor powder into a reaction chamber through a roller flow device for radiation heating, so that atoms are diffused and rearranged, nickel species and iron species are migrated and assembled into intermetallic compounds, and the intermetallic compound nanocrystalline electrocatalytic material is obtained.

[0009] Further, in step (1), the molar ratio of nickel and iron elements in the mixed metal salt is 3:1.

[0010] Further, in step (1), the nickel salt is nickel chloride; and the iron salt is ferric chloride.

[0011] Further, in step (1), the mass ratio of the mixed metal salt to carbon black is 6-12:1.

[0012] Further, in step (2), the freeze-drying is performed for 4-6 h.

[0013] Further, in step (2), the coating amount is 1.5-2 mg / cm 2 .

[0014] Further, in step (2), the radiation heating is performed at 650-750 DEG C for 80-120 s.

[0015] The application also provides the intermetallic compound nanocrystalline electrocatalytic material prepared by the preparation method of the intermetallic compound nanocrystalline electrocatalytic material.

[0016] The application also provides the application of the intermetallic compound nanocrystalline electrocatalytic material in electrocatalytic decomposition of water.

[0017] The application also provides the application of the intermetallic compound nanocrystalline electrocatalytic material in preparation of an electrocatalyst.

[0018] The application has the following beneficial effects: 1、The radiation heating of the method optimizes the nucleation and growth process of ordered nanocrystals. After the high-temperature reaction zone, the material cooled is recovered from the roller flow device to obtain large-scale, ordered intermetallic compound nanocrystalline material loaded on a carbon substrate, and the alloy material achieves excellent performance in alkaline electrocatalytic decomposition of water to produce oxygen. Moreover, this continuous synthesis method not only maintains atomic level control but also realizes high-throughput production by precisely adjusting the structure and composition. Only 10 minutes are needed to realize continuous preparation of a large amount of catalysts.

[0019] 2、The method of the present application shows more favorable environmental advantages than traditional technologies. The ultrafast radiation heating (URH) method proposed by the present application is significantly lower in energy consumption than other synthesis technologies such as thermal annealing, microwave impact, and wet method. In addition, the URH method has three core advantages: no organic solvent process (eliminating volatile organic compound (VOC) emissions), ultra-short processing time (suppressing thermal-induced NO x , SO x generation), and localized heating efficiency (avoiding excess energy loss). At the same time, the roll-flow continuous design not only realizes the industrialized mass production that intermittent processes cannot achieve, but also makes the ultrafast radiation heating (URH) technology a double-optimal path that successfully prepares advanced intermetallic compound nanocatalysts while meeting environmental benefits. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is an example diagram of a roll-flow device and an integrated reaction chamber; Figure 2 is a comparison chart of cumulative energy requirements, resulting global warming potential, and atmospheric pollutant content for different preparation methods; Figure 3 is a structure characterization chart of intermetallic compound nanocrystalline electrocatalytic material L12-Ni3Fe; Figure 4 is a mechanism and performance evaluation chart of L12-Ni3Fe electrocatalytic water decomposition to produce oxygen; Figure 5 is a comparison chart of L12-Ni3Fe and IrO2 anion exchange membrane water electrolysis performance. DETAILED DESCRIPTION

[0021] The principles and features of the present application are described below, and the examples are used only to explain the present application and are not intended to limit the scope of the present application. If no specific conditions are specified in the examples, conventional conditions or manufacturer's recommended conditions are used. If no manufacturer of reagents or instruments is specified, it is a conventional product that can be purchased on the market.

[0022] Example 1 An intermetallic compound nanocrystalline electrocatalytic material, the preparation method thereof comprising the following steps: (1) mixing nickel chloride and iron chloride at a molar ratio of 3:1 to obtain a mixed metal salt; then uniformly mixing the mixed metal salt with carbon black at a mass ratio of 6:1, adding deionized water for ultrasonic dispersion to obtain a precursor solution; (2) freeze-drying the precursor solution obtained in step (1) for 5 h to obtain a precursor powder; mixing the precursor powder at 1.5 mg / cm 2The continuous coating is applied on a flexible substrate and is sent into a reaction chamber through a roller flow device, and is radiantly heated at 700 DEG C for 100 s to make atoms diffuse and rearrange, and nickel species and iron species migrate and assemble into intermetallic compounds, thereby obtaining the intermetallic compound nanocrystalline electrocatalytic material.

[0023] Example 2 An intermetallic compound nanocrystalline electrocatalytic material, and a preparation method thereof comprises the following steps: (1) mixing nickel chloride and iron chloride according to a molar ratio of 3:1 to obtain a mixed metal salt, then uniformly mixing the mixed metal salt and carbon black according to a mass ratio of 8:1, adding deionized water for ultrasonic dispersion to obtain a precursor solution; (2) freeze-drying the precursor solution obtained in step (1) for 4 h to obtain a precursor powder; uniformly mixing the precursor powder according to 1.8 mg / cm 2 The continuous coating is applied on a flexible substrate and is sent into a reaction chamber through a roller flow device, and is radiantly heated at 650 DEG C for 120 s to make atoms diffuse and rearrange, and nickel species and iron species migrate and assemble into intermetallic compounds, thereby obtaining the intermetallic compound nanocrystalline electrocatalytic material.

[0024] Example 3 An intermetallic compound nanocrystalline electrocatalytic material, and a preparation method thereof comprises the following steps: (1) mixing nickel chloride and iron chloride according to a molar ratio of 3:1 to obtain a mixed metal salt, then uniformly mixing the mixed metal salt and carbon black according to a mass ratio of 12:1, adding deionized water for ultrasonic dispersion to obtain a precursor solution; (2) freeze-drying the precursor solution obtained in step (1) for 6 h to obtain a precursor powder; uniformly mixing the precursor powder according to 2 mg / cm 2 The continuous coating is applied on a flexible substrate and is sent into a reaction chamber through a roller flow device, and is radiantly heated at 750 DEG C for 120 s to make atoms diffuse and rearrange, and nickel species and iron species migrate and assemble into intermetallic compounds, thereby obtaining the intermetallic compound nanocrystalline electrocatalytic material.

[0025] Test Example 1 Ni3Fe intermetallic compounds are synthesized by using a thermal annealing method (TA), a microwave shock method (MWS), a wet chemical method (WI) and the method of the present application (URH) respectively, and cumulative energy requirements, global warming potentials and atmospheric pollutant contents caused by different methods are compared.

[0026] (1) An example diagram of a roller flow device and an integrated reaction chamber used in the method of the present application is shown in Figure 1 , wherein A is a substrate feeding and winding module; B and C are radiative heating example diagrams; and D is a sample diagram of the intermetallic compound nanocrystalline electrocatalytic material L12-Ni3Fe prepared by using the method of the present application.

[0027] (2) The comparison chart of cumulative energy demand, global warming potential and atmospheric pollutant content caused by different methods is shown in Figure 2 .

[0028] It can be seen from Figure 2 that the cumulative energy demand required for preparing L12-Ni3Fe by the method of the application (URH) is only 1 / 3 of that of other methods; 0.43 kg of CO2 (eq) is produced by the preparation method of the application (URH), while 1.14-10.5 kg of CO2 (eq) is produced by the alternative methods; the atmospheric pollutants such as NOx, SOx and PM 2.5 produced in the operation process of the preparation method of the application are less than half of those of the TA method (11.68 g-eq.) and the MTS method (11.5 g-eq.), and are 170 times lower than those of the WI method (751.2 g-eq.).

[0029] Test Example 2 The structure characterization chart of the intermetallic compound nanocrystalline electrocatalytic material (L12-Ni3Fe) prepared by the method of the application is shown in Figure 3 , wherein A is the XRD chart of L12-Ni3Fe, from top to bottom are L12-Ni3Fe, disordered Ni3Fe and PDF standard card; B is the schematic diagram of the molecular structure of L12-Ni3Fe; C is the TEM image of L12-Ni3Fe and the EDS element mapping chart of Ni and Fe; D and E are the aberration-corrected HAADF-STEM images of L12-Ni3Fe observed along the

[110] band axis; F is the ideal crystal structure model along the

[110] band axis; G is the schematic diagram of the process of the transformation of the Ni3Fe alloy from the core-shell structure to the ordered structure; H-N are the TEM images and EDS element mapping images of the transformation of the Ni3Fe from the core-shell structure to the ordered structure.

[0030] Test Example 3 Through density functional theory (DFT) calculation, the oxygen evolution reaction (OER) mechanism of the intermetallic compound nanocrystalline electrocatalytic material (L12-Ni3Fe) prepared by the method of the application, disordered Ni3Fe alloy (A1-Ni3Fe) and commercial IrO2 is revealed, and performance evaluation is carried out, and the results are shown in Figure 4 , wherein A is the linear sweep voltammogram of different alloy materials in 1 M KOH, and the scanning rate is 5 mV / s; B is the OER performance comparison chart of different alloy materials, including the overpotential at 10 mA / cm 2 current density, Tafel slope, stability, material synthesis time and cost of the material required; C is the comparison chart of L12-Ni3Fe and commercial IrO2 at a current density of 100 mA / cm 2The chronopotential curves at time (the inset is a schematic diagram of the lattice oxygen mechanism (LOM) on L12-Ni3Fe); D is the adsorption model of LOM in L12-Ni3Fe.

[0031] Depend on Figure 4 It can be seen that L12-Ni3Fe at 10 mA / cm 2 The overpotential at the current density is only 200.2 mV, which is much lower than the 247.5 mV of Ni3Fe alloy; the electrochemical performance and cost of L12-Ni3Fe are superior to disordered Ni3Fe alloy and commercial IrO2.

[0032] Test Example 4 A comparison of the performance of the intermetallic compound nanocrystalline electrocatalytic material (L12-Ni3Fe) prepared by the method of this invention and the anion exchange membrane electrolysis (AEM) of commercial IrO2 is shown below. Figure 5 As shown, A is a schematic diagram of the AEM flow cell; B is a polarization curve of different alloy materials in 1 M KOH without compensation for resistance; and C is a chronopotential curve of water electrolysis.

[0033] Depend on Figure 5 It can be seen that the AEM performance of ordered L12-Ni3Fe is significantly better than that of commercial IrO2 with the same loading; compared with IrO2, L12-Ni3Fe has better performance at 100 mA / cm². 2 The potential stabilization time is longer under current density, approaching 20 hours.

[0034] 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 or improvements 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 intermetallic compound nanocrystalline electrocatalytic material, characterized in that, Includes the following steps: (1) Mix nickel salt and iron salt to obtain a mixed metal salt; then mix the mixed metal salt with carbon black evenly, add deionized water and ultrasonically disperse to obtain a precursor solution; (2) Freeze-dry the precursor solution obtained in step (1) to obtain precursor powder; continuously coat the precursor powder onto a flexible substrate and send it into the reaction chamber for radiation heating through a roller device, so that atoms diffuse and rearrange, nickel species and iron species migrate and assemble into intermetallic compounds, and obtain intermetallic compound nanocrystalline electrocatalytic materials.

2. The method for preparing intermetallic compound nanocrystalline electrocatalytic materials as described in claim 1, characterized in that, In step (1), the molar ratio of nickel to iron in the mixed metal salt is 3:

1.

3. The method for preparing intermetallic compound nanocrystalline electrocatalytic materials as described in claim 1, characterized in that, In step (1), the nickel salt is nickel chloride; the iron salt is ferric chloride.

4. The method for preparing intermetallic compound nanocrystalline electrocatalytic materials as described in claim 1, characterized in that, In step (1), the mass ratio of the mixed metal salt to carbon black is 6:

1.

5. The method for preparing intermetallic compound nanocrystalline electrocatalytic materials as described in claim 1, characterized in that, In step (2), freeze-dry for 4-6 hours.

6. The method for preparing intermetallic compound nanocrystalline electrocatalytic materials as described in claim 1, characterized in that, In step (2), the application amount is 1.5-2 mg / cm³. 2 .

7. The method for preparing intermetallic compound nanocrystalline electrocatalytic materials as described in claim 1, characterized in that, In step (2), radiant heating at 650-750℃ is performed for 80-120 seconds.

8. The intermetallic compound nanocrystalline electrocatalytic material prepared by the preparation method of any one of claims 1-7.

9. The application of the intermetallic compound nanocrystalline electrocatalytic material according to claim 8 in the electrocatalytic splitting of water.

10. The application of the intermetallic compound nanocrystalline electrocatalytic material according to claim 8 in the preparation of electrocatalysts.

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