Preparation method of high-entropy alloy nanoparticle catalyst for waste plastic degradation

Abstract

The application belongs to the technical field of catalyst preparation, and relates to a preparation method and application of a CoCuNiPtRu high-entropy alloy nanoparticle catalyst. A one-pot wet chemical method is used to uniformly mix 4-amino pyridine solvent and metal precursors, and then ascorbic acid is quickly added for reduction in an oil bath at 95 DEG C. After reaction, washing and drying, the catalyst is obtained. The method has the advantages of simple process and convenient operation. The obtained catalyst has high activity and selectivity in catalytic degradation of polylactic acid waste plastics under alkaline conditions, can efficiently upgrade and convert the polylactic acid waste plastics into acetic acid, provides a new way for resource utilization of waste plastics, and has good environmental protection and resource recycling prospects.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation technology, focusing on high-entropy alloy nanoparticle catalysts, and mainly relates to a preparation method of CoCuNiPtRu catalyst and its application. Background Technology

[0002] Plastics are highly resistant to degradation, and fossil-based plastics are difficult to decompose through biological or abiotic processes, leading to their continuous accumulation in landfills and the natural environment. Among various plastics, polylactic acid (PLA) accounts for 24% of the global biodegradable polymer market, and it can eventually decompose into water, carbon dioxide, and biomass in soil. This characteristic makes PLA an environmentally friendly material to replace traditional plastics such as polyethylene and polypropylene. However, excessive disposal of waste PLA in landfills not only wastes resources but also increases greenhouse gas emissions. Therefore, effective measures must be taken to strengthen the management of waste plastics. In this context, using electrochemical processes to convert waste plastics into high-value-added compounds can alleviate environmental pollution problems. Existing research has shown that cobalt selenide supported on palladium foam can oxidize lactic acid, the single product of PLA hydrolysis, to acetate, with a Faraday efficiency of up to 87%. However, to achieve efficient upgrading and recycling of PLA, further improvements in the selectivity and activity of catalysts are still needed.

[0003] High-entropy alloys are novel multimetallic alloys composed of five or more elements, and their physicochemical properties are generally superior to those of traditional alloys. High-entropy alloy catalysts possess unique properties such as thermodynamic high-entropy effects, slow diffusion effects, and cocktail effects, showing great potential in the field of electrocatalytic oxidation. The random distribution of multiple elements can cause lattice distortion, and the electrochemical performance can be enhanced by regulating the electronic structure through synergistic interactions between elements. Furthermore, precisely designing nanomaterial structures is an effective way to improve electrocatalytic activity. Nanoparticles, in particular, are beneficial for electron conduction, improving utilization, reducing surface area loss, and exposing more active sites, thus showing broad application prospects in electrocatalysis. In summary, high-entropy alloy nanoparticles combine the synergistic advantages of morphology, structure, and composition, and are expected to become ideal electrocatalysts; however, this method has not yet been fully utilized.

[0004] This invention employs a green and environmentally friendly one-step wet chemical strategy to prepare high-performance catalysts, simplifying the synthesis steps and reducing the introduction of impurities. The prepared CoCuNiPtRu high-entropy alloy nanoparticle catalyst exhibits excellent electrocatalytic activity and selectivity in the formation of acetic acid. Summary of the Invention

[0005] [Technical problem to be solved] To address the shortcomings of existing technologies, this invention provides a method for preparing high-entropy alloy nanoparticle metal catalysts.

[0006] One objective of this invention is to obtain a high-entropy alloy nanoparticle CoCuNiPtRu catalyst by uniformly mixing a metal precursor with a 4-aminopyridine solution and reacting it in an oil bath for a period of time under the action of the reducing agent ascorbic acid. Technical solution:

[0007] A method for synthesizing a high-entropy alloy nanoparticle CoCuNiPtRu catalyst includes the following steps: 1. Weigh 0.048 g of 4-aminopyridine and dissolve it in 8 ml of ultrapure water. Add 1 ml of each of the five precursors sequentially in an oil bath at 90°C. Shake well and then quickly add 1 ml of 1 M reducing agent ascorbic acid and react for 30 minutes. The molar concentration of each precursor is 20 mM.

[0008] 2. After the reaction is complete, remove the precipitate, wash it by centrifugation with ethanol and water, collect the precipitate and dry it for later use.

[0009] Another objective of this invention is to use the prepared high-entropy alloy nanoparticle CoCuNiPtRu catalyst for the upgrading and conversion of waste plastic polylactic acid into acetic acid.

[0010] Experimental method for the electrocatalytic oxidation of lactic acid in an alkaline environment: An appropriate amount of the prepared catalyst was accurately weighed and placed in a Nafion mixed solution for ultrasonic treatment to ensure uniform dispersion. Subsequently, the dispersion was drop-cast onto the surface of carbon cloth using a drop-coating method. After solvent evaporation, the working electrode was successfully prepared. The Nafion mixed solution was prepared from ultrapure water, ethanol, and a 5 wt% Nafion solution. For the electrochemical testing system, a platinum sheet electrode was selected as the counter electrode, and an Hg / HgO electrode was used as the reference electrode. Together with the prepared working electrode, a three-electrode electrochemical testing system was constructed. Linear sweep voltammetry was performed on the catalyst in alkaline solutions and solutions containing lactic acid. The experimental results clearly show that the nanoparticle-structured high-entropy alloy CoCuNiPtRu catalyst prepared in this invention exhibits superior electrocatalytic activity compared to other control catalysts, demonstrating significant application potential in related electrochemical processes such as lactic acid oxidation.

[0011] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: The high-entropy alloy nanoparticle CoCuNiPtRu catalyst prepared by this method exhibits excellent electrocatalytic oxidation activity for waste plastics under alkaline conditions. This catalyst can efficiently convert PLA into high-value-added chemicals through electrochemical oxidation. This not only provides an efficient and environmentally friendly solution for waste plastic treatment but also achieves effective resource recycling and reuse, creating new economic value while addressing plastic pollution. Attached Figure Description

[0012] Figure 1 This is a TEM image of a high-entropy alloy nanoparticle CoCuNiPtRu catalyst.

[0013] Figure 2 The image shows the XRD pattern of the high-entropy alloy nanoparticle CoCuNiPtRu catalyst.

[0014] Figure 3 The image shows a linear sweep voltammogram of the prepared high-entropy alloy nanoparticle CoCuNiPtRu catalyst in a 1 mol / L KOH solution with or without 0.1 M lactic acid.

[0015] Figure 4 The NMR spectra are for the products analyzed before and after electrolysis of high-entropy alloy nanoparticle CoCuNiPtRu catalyst under 1 mol / L KOH and 0.1 M lactic acid conditions. Detailed Implementation

[0016] Combined with appendix Figure 1-4 The invention will be further described in the following embodiments. Example

[0017] 1. Study on the electrocatalytic oxidation of lactic acid in alkaline environment A three-electrode electrochemical testing system was constructed using a high-entropy alloy nanoparticle CoCuNiPtRu catalyst dropped onto a glass cloth electrode with a cut area of ​​1 cm² as the working electrode, a platinum sheet as the counter electrode, and a saturated Hg / HgO electrode as the reference electrode. Linear sweep voltammetry was performed on the catalyst in 1 mol / L KOH solution with and without 0.1 M lactic acid solution, with a potential window of 1.1–2.0 V.

[0018] Figure 1 The image shown is a transmission electron microscope (TEM) image of the high-entropy alloy nanoparticle CoCuNiPtRu catalyst in Example 1 of this invention, revealing the nanoparticle structure.

[0019] Figure 2 The image shows the XRD pattern of the high-entropy alloy nanoparticle CoCuNiPtRu catalyst described in Example 1 of this invention.

[0020] Figure 3This is a linear sweep voltammogram of the high-entropy alloy nanoparticle CoCuNiPtRu catalyst described in Example 1 of this invention in a 1 mol / L KOH solution with and without 0.1M lactic acid solution. It can be seen that the prepared high-entropy alloy nanoparticle CoCuNiPtRu catalyst exhibits greater thermodynamic advantages and higher activity in catalyzing lactic acid oxidation compared to the oxygen evolution reaction.

[0021] Figure 4 The image shows the 1H NMR spectrum of the high-entropy alloy nanoparticle CoCuNiPtRu catalyst after electrolysis in a 1 mol / L KOH solution containing 0.1 M lactic acid for 10 h. It can be seen that the prepared high-entropy alloy nanoparticle CoCuNiPtRu catalyst exhibits high selectivity for the product acetic acid.

Claims

1. A method for preparing a high-entropy alloy nanoparticle catalyst for waste plastic degradation, characterized in that... This method includes the step of upgrading and recycling waste polylactic acid plastics to obtain acetic acid: (1) Add copper nitrate, cobalt nitrate, ruthenium chloride, potassium chloroplatinate, and nickel chloride precursor solution sequentially to a 4-aminopyridine solution; (2) Then quickly add the reducing agent ascorbic acid; (3) Place the reaction mixture in an oil bath; (4) After the solution obtained in step (3) is allowed to stand, the precipitate is separated and washed and dried in sequence to obtain the nanoparticle CoCuNiPtRu high-entropy alloy metal catalyst.

2. The method for preparing the nanoparticle CoCuNiPtRu high-entropy alloy metal catalyst according to claim 1, characterized in that, The 4-aminopyridine solution in step (1) is prepared by dissolving 0.0475 g of 4-aminopyridine in 7 ml of ultrapure water.

3. The method for preparing the nanoparticle CoCuNiPtRu high-entropy alloy metal catalyst according to claim 1, characterized in that, In step (1), the molar concentration of each metal precursor is 20 mM and the volume added is 1 ml.

4. The method for preparing the nanoparticle CoCuNiPtRu high-entropy alloy metal catalyst according to claim 2, characterized in that, The ascorbic acid molar concentration in step (2) is 1 M, and the volume added is 1 ml.

5. The method for preparing the nanoparticle CoCuNiPtRu high-entropy alloy metal catalyst according to claim 3, characterized in that, The oil bath temperature in step (3) is 95°C.

6. The method for preparing the nanoparticle CoCuNiPtRu high-entropy alloy metal catalyst according to claim 3, characterized in that, The reaction time in step (3) is 10 minutes.

7. The nanoparticle CoCuNiPtRu high-entropy alloy metal catalyst prepared by the method according to claims 1-6.

8. The application of the nanoparticle CoCuNiPtRu high-entropy alloy metal catalyst according to claim 7, characterized in that, The nanoparticle CoCuNiPtRu high-entropy alloy metal catalyst was used to degrade polylactic acid from waste plastics to produce acetic acid.

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