High-entropy intermetallic compound, preparation method and application thereof

Abstract

A high-entropy intermetallic compound, a preparation method and application thereof, relate to the field of catalyst technology, and solve the problems of multiple ethylene glycol oxidation reaction paths, complex products, and uneven distribution of existing high-entropy alloy catalyst sites. The high-entropy intermetallic compound is a PtPdFeMoBi high-entropy alloy loaded on a carbon nanofiber carrier. The preparation method comprises the following steps: preparing an electrospinning solution by taking metal salt, N,N-dimethylformamide and polyacrylonitrile as raw materials, stirring, and then obtaining a precursor by electrospinning, and then baking the precursor in a tube furnace to obtain the high-entropy intermetallic compound PtPdFeMoBi / CNFs. The application of the high-entropy intermetallic compound as a catalyst in the electro-catalytic oxidation of ethylene glycol to synthesize glycolic acid is outstanding in the efficient and high-selectivity preparation of glycolic acid, has a good industrial application prospect, and has a wide application prospect in the field of PET plastic recycling.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a high-entropy intermetallic compound, its preparation method, and its applications. Background Technology

[0002] Electrolysis of water is a green and efficient hydrogen production technology, but the slow kinetics and high overpotential of the oxygen evolution reaction (OER) at the anolyte severely limit overall energy efficiency. Replacing OER with a thermodynamically more favorable small-molecule oxidation reaction can significantly reduce electrolysis energy consumption and simultaneously produce high-value-added chemicals. Ethylene glycol oxidation reaction (EGOR) is one of the most promising alternative reactions, with its ideal product being glycolic acid (GA), which can be widely used in biomedicine, food processing, industrial cleaning, and metal finishing, possessing high economic value. Furthermore, the resource recycling of waste polyethylene terephthalate (PET) plastic has become an important research direction, as its degradation products mainly include ethylene glycol. Further efficiently converting the recovered ethylene glycol into high-value-added chemicals can significantly improve the economic value and environmental benefits of PET recycling.

[0003] Currently, the electrocatalytic oxidation of ethylene glycol faces two major challenges. First, the reaction pathway is complex, with diverse intermediates, and it easily generates byproducts such as formic acid and oxalic acid, resulting in low selectivity and Faraday efficiency for glycolic acid. Second, traditional catalysts have uneven distribution of active sites and poor structural stability, making it difficult to simultaneously achieve high activity, high selectivity, and long lifespan.

[0004] High-entropy alloys (HEAs) have shown great potential in electrocatalysis due to their multi-principal-component synergistic effects, tunable electronic structure, and lattice distortion effects. However, conventional HEAs are mostly disordered solid solutions with random atomic arrangements leading to heterogeneous active sites and large differences in the reaction microenvironment, which easily triggers side reactions and reduces the selectivity of the target product. In contrast, high-entropy intermetallic compounds (HEIs) combine high-entropy effects with long-range ordered atomic arrangements, enabling precise arrangement of active sites and fine control of electronic structure, fundamentally improving the problem of site heterogeneity. They are ideal catalytic materials for the efficient and highly selective oxidation of ethylene glycol to glycolic acid. However, existing high-entropy intermetallic compounds generally suffer from drawbacks such as harsh preparation conditions, low phase purity, easy phase separation, and difficulty in controlling structural order, making it difficult to prepare high-performance electrocatalysts on a large scale.

[0005] In summary, there is an urgent need to develop a high-entropy intermetallic compound preparation technology that is simple in process, has a controllable structure, and exhibits excellent catalytic performance, in order to solve the problems of poor selectivity, low efficiency, and unstable catalyst structure in the electro-oxidation of ethylene glycol. Summary of the Invention

[0006] To address the issues of multiple reaction pathways and complex products in ethylene glycol oxidation, as well as the uneven distribution of catalyst sites in existing high-entropy alloys, this invention provides a high-entropy intermetallic compound material, its preparation method, and its applications.

[0007] The specific technical solution of the present invention is as follows: A method for preparing a high-entropy intermetallic compound, wherein the high-entropy intermetallic compound uses carbon nanofibers as a carrier and is loaded with a PtPdFeMoBi high-entropy alloy. The preparation method includes the following steps: An electrospinning solution was prepared using metal salts, N,N-dimethylformamide, and polyacrylonitrile as raw materials. After stirring, a precursor was obtained by electrospinning. The precursor was then calcined in a tube furnace to obtain the high-entropy intermetallic compound PtPdFeMoBi / CNFs.

[0008] Preferably, the metal salt includes platinum acetylacetonate, palladium acetylacetonate, iron acetylacetonate, molybdenum acetylacetonate, and bismuth nitrate.

[0009] Preferably, the molar amounts of platinum acetylacetone, palladium acetylacetone, iron acetylacetone, molybdenum acetylacetone, and bismuth nitrate in the electrospinning solution are the same.

[0010] Preferably, the mass ratio of N,N-dimethylformamide to polyacrylonitrile is 11:1.

[0011] Preferably, the stirring time is 6 hours.

[0012] Preferably, the sample feed rate for electrospinning is 0.3~0.5 mL / min. -1 The receiving distance is 15~20 cm, the positive voltage is 15~18 kV, and the negative voltage is -0.6 kV.

[0013] Preferably, during the firing process, the precursor is sandwiched between two graphite sheets, and the graphite sheets are fixed by wrapping them with iron wire.

[0014] Preferably, the firing parameters are as follows: First, heat from room temperature to 230 °C for pre-oxidation for 3 h, at a heating rate of 2 °C / min. -1 ; Argon gas was then introduced, and the temperature was raised to 1000 °C and held for 3 hours at a rate of 5 °C / min. -1 Then it was allowed to cool naturally to room temperature.

[0015] The present invention also provides a high-entropy intermetallic compound prepared by the above preparation method.

[0016] The present invention also provides an application of the above-mentioned high-entropy intermetallic compound, specifically as a catalyst in the oxidation reaction of ethylene glycol.

[0017] This invention employs a lattice compensation strategy combined with spatial confinement effects to precisely control the crystal structure of high-entropy intermetallic compounds. By introducing Bi and Mo with large atomic radii, the phase separation tendency caused by entropy reduction is effectively counteracted through lattice compensation, stabilizing the formation of L10-type long-range ordered intermetallic compounds. This fundamentally solves the problem of uneven distribution of active sites in traditional catalysts, significantly improving catalytic performance. Compared with existing technologies, the specific beneficial effects of this invention are as follows: 1. This invention overcomes the shortcomings of conventional disordered high-entropy alloys, such as uneven reaction microenvironment, uncontrollable reaction pathways, low Faraday efficiency, and complex byproducts caused by the random distribution of active sites. By constructing a long-range ordered arrangement of active sites, highly homogenized Pt active centers are achieved, suppressing the generation of inefficient / inactive sites; at the same time, the synergistic effect of carbophilic and oxyphilic sites is enhanced, the co-adsorption of reactants and the directional transformation of reaction intermediates are optimized, significantly improving the selectivity of target products and greatly reducing the generation of byproducts.

[0018] 2. This invention utilizes a dual strategy of lattice compensation and electrospinning spatial confinement to highly disperse metal nanoparticles within a porous carbon nanofiber structure. During high-temperature annealing, the atoms are guided to arrange themselves in an orderly manner, reducing the risk of phase separation induced by entropy reduction. This successfully prepares a single-phase, highly ordered, high-entropy intermetallic compound, significantly improving catalytic activity and structural stability.

[0019] 3. The preparation method provided by this invention is simple, has controllable conditions, and good reproducibility. The electrocatalytic performance of the high-entropy intermetallic compound obtained is significantly better than that of existing reported materials. It shows outstanding performance in the efficient and selective electrocatalytic oxidation of ethylene glycol to prepare glycolic acid and has good prospects for industrial application.

[0020] 4. The high-entropy intermetallic compound catalyst prepared in this invention can efficiently catalyze the selective oxidation of ethylene glycol obtained from PET recycling, realizing the conversion of waste PET plastic into high-value glycolic acid, providing an efficient catalytic technology route for the resource utilization of PET, and possessing both environmental and economic value. Attached Figure Description

[0021] Figure 1 The XRD pattern of the high-entropy intermetallic compound PtPdFeMoBi / CNFs prepared in Example 1; Figure 2 The XRD pattern of the high-entropy alloy PtPdFeInBi / CNFs prepared in Comparative Example 1. Figure 3 The XRD pattern of the high-entropy alloy PtPdFeSnBi / CNFs prepared in Comparative Example 2; Figure 4SEM image of the high-entropy intermetallic compound PtPdFeMoBi / CNFs prepared in Example 1; Figure 5 HAADF-STEM image of the high-entropy intermetallic compound PtPdFeMoBi / CNFs prepared in Example 1; Figure 6 LSV curves of high-entropy intermetallic compound PtPdFeMoBi / CNFs prepared in Example 1; Figure 7 LSV curves of the high-entropy alloy PtPdFeInBi / CNFs prepared for Comparative Example 1. Figure 8 LSV curves of the high-entropy alloy PtPdFeSnBi / CNFs prepared in Comparative Example 2; Figure 9 The high-entropy catalytic materials prepared in Example 1 and Comparative Examples 1-2 are shown in the 1-h potentiostatic polarization curves. Figure 10 The 1H NMR spectrum of the anolyte after the high-entropy catalytic materials prepared in Example 1 and Comparative Examples 1-2 were subjected to constant potential polarization for 1 h. Figure 11 The Faraday efficiency and yield of the high-entropy catalytic materials prepared in Example 1 and Comparative Examples 1-2 are compared. Detailed Implementation

[0022] To make the technical solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that the following embodiments are only used to better understand the technical solutions of the present invention and should not be construed as limiting the present invention.

[0023] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0024] Example 1. The specific steps for preparing high-entropy intermetallic compounds in this embodiment are as follows: Weigh out 0.0625 mmol each of platinum acetylacetone, palladium acetylacetone, iron acetylacetone, molybdenum acetylacetone, and bismuth nitrate, 2.75 g of DMF, and 0.25 g of PAN, and mix thoroughly for 6 h. Inject at a positive voltage of 16 kV, a receiving distance of 20 cm, and an injection rate of 0.5 mL / min. -1Under specific conditions, electrospinning was performed to obtain the precursor film. Pre-oxidation was carried out by heating at 230 °C for 3 h in an air atmosphere, followed by purging with argon gas and further reaction at 1000 °C for 3 h. The resulting sample was PtPdFeMoBi / CNFs.

[0025] Comparative Example 1. The difference between this comparative example and Example 1 is as follows: The metal salts used were platinum acetylacetonate, palladium acetylacetonate, iron acetylacetonate, indium chloride, and bismuth nitrate. All other operations were the same as in Example 1. The resulting high-entropy alloy was named PtPdFeInBi / CNFs.

[0026] Comparative Example 2. The difference between this comparative example and Example 1 is as follows: The metal salts used were platinum acetylacetonate, palladium acetylacetonate, iron acetylacetonate, anhydrous stannous chloride, and bismuth nitrate. All other operations were the same as in Example 1. The resulting high-entropy alloy was named PtPdFeSnBi / CNFs.

[0027] Example of results. (1) The high-entropy catalytic materials prepared in Example 1, Comparative Example 1 and Comparative Example 2 were characterized by XRD, and the results are as follows: Figure 1 , Figure 2 and Figure 3 As shown. By Figure 1 As can be seen, the XRD pattern of the sample in Example 1 shows a single FePt phase with no impurity peaks; while Comparative Examples 1 and 2 both exhibit FePt phase and obvious second phase, displaying typical characteristics of disordered alloy solid solutions. This proves that the present invention successfully prepared a high-purity single-phase high-entropy intermetallic compound.

[0028] (2) The surface microstructure of the high-entropy intermetallic compound prepared in Example 1 was characterized by scanning electron microscopy, and the results are as follows: Figure 4 As shown. By Figure 4 It can be seen that the high-entropy intermetallic compound particles are uniformly loaded on the surface of carbon nanofibers, with particle sizes ranging from 25 to 40 nm, exhibiting good dispersibility and no obvious agglomeration.

[0029] (3) The atomic arrangement of the high-entropy intermetallic compound prepared in Example 1 was characterized using HAADF-STEM, and the results are as follows: Figure 5 As shown. By Figure 5As can be seen, the sample exhibits clear alternating bright and dark stripes, which originate from the difference in Z-contrast between different atoms. Pt atoms have high Z-contrast and strong electron scattering ability, appearing as bright spots in the image; Fe atoms have low Z-contrast and weak electron scattering ability, appearing as dark areas. This regular and ordered arrangement of bright and dark stripes directly confirms that PdFeMoBi / CNFs possesses a long-range ordered crystal structure, providing intuitive evidence for the successful synthesis of high-entropy intermetallic compounds.

[0030] (4) The high-entropy catalytic materials prepared in Example 1 and Comparative Examples 1-2 were subjected to LSV testing, and the test results are as follows: Figures 6-8 As shown in the figure, the entropy intermetallic compound of Example 1 exhibits the highest peak current density and the widest electrocatalytic activity window, significantly outperforming the disordered high-entropy alloy of the comparative example, fully demonstrating the structural advantages of high-entropy intermetallic compounds in electrocatalytic applications.

[0031] (5) The high-entropy catalytic materials prepared in Example 1 and Comparative Examples 1-2 were subjected to constant potential polarization tests for 1 h, and the electrolytes after the tests were examined by nuclear magnetic resonance (NMR) hydrogen spectroscopy. The NMR internal standard was 0.1 mol L. -1 Potassium benzoate was used, and heavy water was used as the deuteration reagent. The EGOR Faraday efficiency and yield in Examples 1 and Comparative Examples 1-2 were calculated using the internal standard method. Figure 10 It can be seen that, within the same reaction time, Example 1 showed the highest glycolic acid yield with almost no formic acid produced as a byproduct. Figure 11 It can be seen that the Faraday efficiency and product yield of Example 1 are higher than those of Comparative Examples 1-2, with the Faraday efficiency reaching as high as 96.9%, which fully demonstrates that the high-entropy intermetallic compound prepared by the present invention has excellent electrocatalytic activity, selectivity and stability.

[0032] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a high-entropy intermetallic compound, characterized in that, The high-entropy intermetallic compound uses carbon nanofibers as a carrier and loads a PtPdFeMoBi high-entropy alloy. The preparation method includes the following steps: An electrospinning solution was prepared using metal salts, N,N-dimethylformamide, and polyacrylonitrile as raw materials. After stirring, a precursor was obtained by electrospinning. The precursor was then calcined in a tube furnace to obtain the high-entropy intermetallic compound PtPdFeMoBi / CNFs.

2. The method for preparing high-entropy intermetallic compounds according to claim 1, characterized in that, The metal salts include platinum acetylacetonate, palladium acetylacetonate, iron acetylacetonate, molybdenum acetylacetonate, and bismuth nitrate.

3. The method for preparing high-entropy intermetallic compounds according to claim 2, characterized in that, The molar amounts of platinum acetylacetone, palladium acetylacetone, iron acetylacetone, molybdenum acetylacetone, and bismuth nitrate in the electrospinning solution are the same.

4. The method for preparing high-entropy intermetallic compounds according to claim 1, characterized in that, The mass ratio of N,N-dimethylformamide to polyacrylonitrile is 11:

1.

5. The method for preparing high-entropy intermetallic compounds according to claim 1, characterized in that, The stirring time is 6 hours.

6. The method for preparing high-entropy intermetallic compounds according to claim 1, characterized in that, The feed rate for electrospinning is 0.3~0.5 mL / min. -1 The receiving distance is 15~20 cm, the positive voltage is 15~18 kV, and the negative voltage is -0.6 kV.

7. The method for preparing high-entropy intermetallic compounds according to claim 1, characterized in that, During the firing process, the precursor is sandwiched between two graphite sheets, which are then secured with wire.

8. The method for preparing high-entropy intermetallic compounds according to claim 1, characterized in that, The specific firing parameters are as follows: First, heat from room temperature to 230 °C for pre-oxidation for 3 h, at a heating rate of 2 °C / min. -1 ; Argon gas was then introduced, and the temperature was raised to 1000 °C and held for 3 hours at a rate of 5 °C / min. -1 Then it was allowed to cool naturally to room temperature.

9. A high-entropy intermetallic compound prepared by any one of claims 1 to 8.

10. An application of the high-entropy intermetallic compound as described in claim 9, characterized in that, It is used as a catalyst in the oxidation of ethylene glycol.

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