A high-entropy alloy nanozyme, its preparation method and application

Abstract

This invention belongs to the field of nanoenzyme materials technology, and specifically relates to a high-entropy alloy nanoenzyme, its preparation method, and its applications. The high-entropy alloy nanoenzyme of this invention comprises nitrogen-doped carbon nanomaterials and a high-entropy alloy; the high-entropy alloy is loaded onto the nitrogen-doped carbon nanomaterials. This invention constructs a highly efficient dual-enzyme active high-entropy alloy sensing platform using nitrogen-doped carbon nanomaterials and a high-entropy alloy, exhibiting both oxidase and peroxidase activities. Utilizing its oxidase activity in reaction with a chromogenic agent, and by referencing the change in the ultraviolet absorption peak at 652 nm, pesticide residues are detected. This method achieves pesticide residue detection that is simple to operate, low in cost, and highly sensitive. The detection limit of this method can reach as low as 0.005 μmol of pesticide residues, far lower than the detection limits of existing pesticide residue detection technologies. Simultaneously, in the presence of H2O2, the high-entropy alloy nanoenzyme + H2O2 generates free radicals, which can degrade the organic dye MB.

Description

Technical Field

[0001] This invention belongs to the field of nanoenzyme materials technology, and specifically relates to a high-entropy alloy nanoenzyme, its preparation method, and its application. Background Technology

[0002] The widespread use of pesticides to control weeds and pests and increase crop yields has led to excessive and inappropriate use of pesticides, resulting in high levels of pesticide residues in agricultural products. These residues are persistent in biological or chemical degradation and exhibit strong bioaccumulation in plant and animal tissues. When these compounds accumulate and enter the human body, they pose a serious threat to human health and may cause various functional disorders. Therefore, the detection of pesticides in agricultural products is crucial. Currently, many methods for detecting pesticide residues suffer from insufficient specificity, susceptibility to interference, and limited catalytic efficiency and stability, affecting detection sensitivity.

[0003] Meanwhile, the various organic pollutants contained in wastewater have always been a potential threat to human health. Currently, technologies for degrading organic pollutants still have some shortcomings, such as: degradation efficiency needs to be improved, treatment costs are high, and environmental adaptability is poor.

[0004] High-entropy alloys (HEAs) exhibit excellent catalytic activity, structural stability, and corrosion resistance due to the synergistic effect of their multiple components, making them irreplaceable in high-end fields such as electrocatalysis, energy storage, and catalytic degradation. With the rapid upgrading of industries such as new energy and environmental protection, the market demand for high-performance high-entropy alloy materials continues to grow, especially demanding higher requirements for their compositional uniformity, dispersibility, and catalytic efficiency. Currently, the preparation of high-entropy alloys mostly employs traditional methods such as mechanical alloying and electric arc melting, which suffer from problems such as poor compositional uniformity, severe particle agglomeration, and the need for harsh high-temperature and high-pressure conditions. Although some studies have attempted to prepare high-entropy alloys by loading metal salts onto carbon supports, existing carbon supports (such as activated carbon and graphene) have defects such as limited specific surface area, insufficient metal ion anchoring sites, and weak interfacial bonding with the alloy, leading to easy agglomeration and poor dispersibility of alloy particles, making it difficult to fully utilize the synergistic performance of multiple components.

[0005] Furthermore, in existing carbon-supported metal salt preparation processes, there are insufficient anchoring points on the support and weak bonding with the alloy interface, which cannot effectively suppress alloy particle agglomeration. Moreover, when preparing multi-metal alloys using traditional metal-organic framework (MOF) pyrolysis strategies, the metal composition is unevenly distributed, platinum group metal-based MOF synthesis is difficult, and the utilization rate of metal precursors is low, resulting in poor controllability of product crystal form.

[0006] Therefore, it is of great significance to provide a material that can detect pesticide residues with high sensitivity and effectively degrade organic pollutants. Summary of the Invention

[0007] The present invention aims to solve one or more technical problems existing in the prior art, and at least provide a beneficial alternative. Specifically, the present invention provides a high-entropy alloy nanozyme that can detect pesticide residues with high sensitivity, and can also effectively degrade organic pollutants.

[0008] The inventive concept of this invention: The high-entropy alloy nanozyme of this invention comprises nitrogen-doped carbon nanomaterials and a high-entropy alloy; the high-entropy alloy is loaded on the nitrogen-doped carbon nanomaterials. This invention constructs a highly efficient dual-enzyme active high-entropy alloy sensing platform with both oxidase and peroxidase activities through the nitrogen-doped carbon nanomaterials and the high-entropy alloy. Utilizing its oxidase activity to react with a chromogenic agent, and by referencing the change in the ultraviolet absorption peak at 652 nm, pesticide residues can be detected, achieving pesticide residue detection that is simple to operate, low in cost, and has good sensitivity. In the presence of H2O2, the high-entropy alloy nanozyme + H2O2 generates free radicals, which can achieve the degradation of the organic dye methylene blue (MB).

[0009] Therefore, a first aspect of the present invention provides a high-entropy alloy nanozyme.

[0010] Specifically, the high-entropy alloy nanoenzyme comprises nitrogen-doped carbon nanomaterials and a high-entropy alloy; the high-entropy alloy is loaded on the nitrogen-doped carbon nanomaterials.

[0011] Preferably, the high-entropy alloy is a high-entropy alloy comprising Co, Fe, Cu, Ru, and Pd.

[0012] Preferably, in the high-entropy alloy nanozyme, the mass percentage of Co is 28.99%, the mass percentage of Fe is 11.60%, the mass percentage of Cu is 21.85%, the mass percentage of Ru is 8.99%, and the mass percentage of Pd is 28.57%.

[0013] A second aspect of the present invention provides a method for preparing the high-entropy alloy nanozyme described in the first aspect of the present invention.

[0014] Specifically, the preparation method of the high-entropy alloy nanozyme includes the following steps: (1) The ZIF-67 material was pyrolyzed to obtain a composite material of nitrogen-doped carbon nanomaterials loaded with cobalt nanoparticles; (2) The nitrogen-doped carbon nanomaterials loaded with cobalt nanoparticles obtained in step (1) are mixed with a metal salt and reacted to obtain a precursor composite material. (3) The precursor composite material is subjected to pyrolysis treatment to obtain the product.

[0015] Specifically, this invention utilizes a 3D ZIF-67-assisted pyrolysis-displacement-alloying strategy for preparing high-entropy alloy nanoparticles. Using 3D ZIF-67 nanosheets as the initial template, a three-step method—pyrolysis to prepare a cobalt-nitrogen-doped carbon support, electrochemical displacement (galvanic displacement) to load multi-metals, and thermally induced alloying—is employed to prepare highly dispersed, high-purity, and compositionally tunable high-entropy alloy nanoparticles. This method overcomes many bottlenecks in existing technologies, yielding high-entropy alloy nanozymes (HEA nanozyme materials) with both oxidase and peroxidase activities. The oxidase activity reacts with 3,3',5,5'-tetramethylbenzidine (TMB), and the change in the UV absorption peak at 652 nm is used to detect pesticide residues, providing a simple, low-cost, and highly sensitive method for pesticide residue detection. Furthermore, the peroxidase activity catalyzes the generation of free radicals from H₂O₂, achieving the degradation of the organic dye MB.

[0016] Preferably, in step (1), the preparation method of the ZIF-67 material includes the following steps: The cobalt salt, 2-methylimidazole, and solvent were mixed and reacted to obtain the product.

[0017] Specifically, this invention uses 3D ZIF-67 as a template. Its high specific surface area promotes the exposure of metal particles, avoids phase separation, and ensures product uniformity. Furthermore, due to the presence of Co, other metal salts replace Co rather than adsorb it. Substitution is easier than adsorption, resulting in a metal precursor (metal salt) utilization rate of up to 90%, significantly reducing precious metal consumption. The process is simple and can be mass-produced. The alloy composition and crystal form can be precisely controlled, achieving a phase transition from hexagonal close-packed (hcp) to face-centered cubic (fcc) through component optimization, thus optimizing catalytic performance.

[0018] Specifically, compared to ZIF-8, the use of ZIF-67 as a carrier in this invention has the following advantages: (1) Higher metal supply efficiency: ZIF-67 uses Co as the metal center and can directly form Co nanoparticles after pyrolysis without the need to introduce additional metal sources. It can be directly used as a sacrificial template for galvanic substitution reaction and provide an efficient electron donor for multi-metal deposition. In contrast, the Zn center of ZIF-8 is easy to volatilize and lose during pyrolysis, making it difficult to form stable metal particles. It requires additional loading of metal components, which increases the complexity of the process.

[0019] (2) Better structural adaptability: In the porous nitrogen-doped carbon (NC) support formed by the pyrolysis of ZIF-67, there is a strong interaction between Co and nitrogen atoms, which can build stable Co-N anchoring points. Combined with the high specific surface area and three-dimensional structure retained after the pyrolysis of its 3D nanosheets, it can effectively inhibit the agglomeration of alloy particles and improve the exposure of active sites. Although ZIF-8 can form a nitrogen-doped carbon support, it lacks strong metal-nitrogen coordination, has insufficient anchoring points, and its three-dimensional morphology results in low surface utilization.

[0020] (3) Stronger performance regulation capability: Co derived from ZIF-67 can directly participate in alloying, and induce the crystal form to change from hcp to fcc through component regulation, optimize the adsorption strength of reaction intermediates and reaction energy barrier, and significantly improve catalytic performance; while ZIF-8 has no residual metal components and cannot participate in alloy phase regulation, and needs to rely on the complex ratio of external metals, making it difficult to achieve precise electronic structure and performance optimization.

[0021] Preferably, in the preparation process of the ZIF-67 material, the molar ratio of the cobalt salt to 2-methylimidazole is 1:(3-5); more preferably, the molar ratio of the cobalt salt to 2-methylimidazole is 1:(3.6-4.5); even more preferably, the molar ratio of the cobalt salt to 2-methylimidazole is 1:4.

[0022] Preferably, the cobalt salt comprises Co(NO3)2·6H2O.

[0023] Preferably, in the preparation process of the ZIF-67 material, the reaction time is 2-4 hours; more preferably, in the preparation process of the ZIF-67 material, the reaction time is 2.5-3.5 hours; even more preferably, in the preparation process of the ZIF-67 material, the reaction time is 3 hours.

[0024] Preferably, in step (1), the temperature of the pyrolysis treatment is 500-700℃, and the holding time of the pyrolysis treatment is 1.5-2.5h; more preferably, the temperature of the pyrolysis treatment is 550-650℃, and the holding time of the pyrolysis treatment is 1.8-2.2h; even more preferably, the temperature of the pyrolysis treatment is 600℃, and the holding time of the pyrolysis treatment is 2h.

[0025] Preferably, in step (1), the heating rate of the pyrolysis treatment is 1.5-2.5℃ / min; more preferably, the heating rate of the pyrolysis treatment is 1.8-2.2℃ / min; and even more preferably, the heating rate of the pyrolysis treatment is 2℃ / min.

[0026] Specifically, the nitrogen-doped carbon nanomaterial-loaded cobalt nanoparticle composite material obtained in step (1) is a porous nitrogen-doped carbon nanomaterial-loaded cobalt nanoparticle composite material.

[0027] Preferably, in step (2), the metal salt includes Fe salt, Cu salt, Ru salt and Pd salt.

[0028] Preferably, the molar ratio of Fe salt, Cu salt, Ru salt and Pd salt in the metal salt is (0.8-1.2):(0.8-1.2):(0.8-1.2)1; more preferably, the molar ratio of Fe salt, Cu salt, Ru salt and Pd salt in the metal salt is (0.9-1.1):(0.9-1.1):(0.9-1.1):1; even more preferably, the molar ratio of Fe salt, Cu salt, Ru salt and Pd salt in the metal salt is 1:1:1:1.

[0029] Preferably, the Fe salt includes FeCl3.

[0030] Preferably, the Cu salt comprises CuCl2.

[0031] Preferably, the Ru salt comprises RuCl3·xH2O.

[0032] Preferably, the Pd salt comprises NaPtCl6.

[0033] Preferably, in step (2), the ratio of the nitrogen-doped carbon nanomaterial-loaded cobalt nanoparticle composite material to any one of Fe salt, Cu salt, Ru salt and Pd salt is 50 mg: (18-20) µmol; more preferably, the ratio of the nitrogen-doped carbon nanomaterial-loaded cobalt nanoparticle composite material to any one of Fe salt, Cu salt, Ru salt and Pd salt is 50 mg: 19.2 µmol.

[0034] Preferably, in step (2), the reaction time is 11-13 hours; more preferably, in step (2), the reaction time is 11.5-12.5 hours; even more preferably, in step (2), the reaction time is 12 hours.

[0035] Specifically, in step (2), a spontaneous galvanic substitution reaction occurs by utilizing the difference in redox potential between Co nanoparticles and other metal cations. Co nanoparticles act as sacrificial templates, transferring electrons to metal cations with a more positive redox potential, causing them to deposit on the surface of the support to form a precursor composite material, namely the Co-M intermediate composite material.

[0036] Preferably, in step (3), the temperature of the pyrolysis treatment is 300-500℃ and the holding time of the pyrolysis treatment is 1.5-2.5h; more preferably, the temperature of the pyrolysis treatment is 350-450℃ and the holding time of the pyrolysis treatment is 1.8-2.2h; even more preferably, the temperature of the pyrolysis treatment is 400℃ and the holding time of the pyrolysis treatment is 2h.

[0037] Preferably, in step (3), the heating rate of the pyrolysis treatment is 1.5-2.5℃ / min; more preferably, the heating rate of the pyrolysis treatment is 1.8-2.2℃ / min; and even more preferably, the heating rate of the pyrolysis treatment is 2℃ / min.

[0038] Specifically, in step (3), pyrolysis is used to promote the complete alloying of different metal components, and finally high-entropy alloy nanoparticles are uniformly dispersed on the carrier. The alloy components can be flexibly controlled and can contain up to 5 different metal elements.

[0039] A third aspect of the present invention provides the application of the high-entropy alloy nanozyme described in the first aspect of the present invention in pesticide residue detection and organic pollutant degradation.

[0040] Preferably, the organic pollutant includes organic dyes.

[0041] Compared with the prior art, the beneficial effects of the technical solution provided by the present invention are as follows: (1) This invention constructs a highly efficient dual-enzyme active high-entropy alloy sensing platform using nitrogen-doped carbon nanomaterials and high-entropy alloys, exhibiting both oxidase and peroxidase activities. By utilizing its oxidase activity in reaction with a chromogenic agent and referencing changes in the ultraviolet absorption peak at 652 nm, pesticide residues can be detected. This method offers simple operation, low cost, and high sensitivity, with a detection limit as low as 0.005 μmol, far below the detection limits of existing pesticide residue detection technologies. Simultaneously, in the presence of H2O2, the high-entropy alloy nanoenzyme + H2O2 generates free radicals, which can degrade the organic dye MB.

[0042] (2) The ZIF-67 of this invention uses Co as the metal center. After pyrolysis, it can directly form Co nanoparticles without the need for an additional metal source. It can be directly used as a sacrificial template for galvanic substitution reaction, providing an efficient electron donor for multi-metal deposition. At the same time, after pyrolysis, Co and nitrogen atoms have strong interactions, which can build stable Co-N anchoring sites, effectively inhibiting alloy particle agglomeration and increasing the exposure of active sites.

[0043] (3) The preparation process of this invention is relatively simple, easy to operate and scale up. At the same time, the raw materials used are relatively inexpensive and easy to obtain, the energy consumption of the pyrolysis preparation process is relatively low, and the detection process does not require expensive large-scale instruments and equipment, only conventional equipment such as ultraviolet-visible spectrophotometers, which greatly reduces the cost of pesticide residue detection and is conducive to its promotion and application in grassroots testing institutions or agricultural production sites.

[0044] (4) The high-entropy alloy nanoenzyme of the present invention can detect pesticide residues quickly and accurately, which helps to ensure the quality and safety of agricultural products, reduce the flow of agricultural products with excessive pesticide residues into the market, and has a positive significance for maintaining the health of consumers and enhancing the market competitiveness of agricultural products. At the same time, it provides technical support for the rational use of pesticides in agricultural production and promotes the green and sustainable development of agriculture. Attached Figure Description

[0045] Figure 1 This is a scanning electron microscope image of ZIF-67 prepared in Example 1 of the present invention; Figure 2 This is a scanning electron microscope image of the composite material of porous nitrogen-doped carbon nanomaterials supported on cobalt nanoparticles prepared in Example 1 of the present invention; Figure 3 The images show scanning electron microscopy, transmission electron microscopy, and particle size distribution of the high-entropy alloy nanozyme of Example 1 of this invention. Figure 4 The image shows a transmission electron microscope (TEM) image and particle size distribution of the MEA nanozyme material in Comparative Example 2 of this invention. Figure 5 The image shows a transmission electron microscope and particle size distribution diagram of the LEA nanozyme material in Comparative Example 1 of this invention. Figure 6 This is a graph showing the pesticide residue detection results of the high-entropy alloy nanozyme in Example 1 of the present invention; Figure 7 This is a fitting curve diagram for the detection of zinc thiocarbamate in this invention; Figure 8 The infrared and Raman spectra of the system after the high-entropy alloy nanoenzyme of this invention reacts with pesticide residues. Figure 9 This is a diagram showing the degradation effect of the high-entropy alloy nanozyme on MB in Example 1 of the present invention; Figure 10 This is a comparison chart of the oxidase activities of the high-entropy alloy nanozyme of Example 1, the LEA nanozyme material of Comparative Example 1, and the MEA nanozyme material of Comparative Example 2 of the present invention. Figure 11 This is a comparison chart of the peroxidase activities of the high-entropy alloy nanozyme of Example 1, the LEA nanozyme material of Comparative Example 1, and the MEA nanozyme material of Comparative Example 2 of the present invention. Figure 12 The figure shows the stability test results of the high-entropy alloy nanozyme in Example 1 of the present invention. Detailed Implementation

[0046] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0047] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0048] Example 1 This embodiment provides a method for preparing high-entropy alloy nanozymes, the steps of which are as follows: (1) Synthesis of 3D ZIF-67 by solvothermal method Co(NO3)2·6H2O and 2-methylimidazole were dissolved in methanol at a molar ratio of 1:4, stirred for 3 h, centrifuged, washed, and dried under vacuum for 12 h to obtain 3D ZIF-67 nanosheets. These nanosheets have a high specific surface area and a regular three-dimensional structure, which provides a structural basis for the uniform dispersion of subsequent metal components. (2) Pyrolysis preparation of composite materials of porous nitrogen-doped carbon nanomaterials supported on cobalt nanoparticles (Co NPs) 100 mg ZIF-67 was placed in a tube furnace and heated to 600 °C at 2 °C / min under a nitrogen atmosphere. The temperature was maintained for 2 h, the organic ligands were decomposed and removed, and Co ions were converted into Co nanoparticles in situ. After natural cooling, a composite material of porous nitrogen-doped carbon nanomaterials loaded with Co NPs was formed. (3) Galvanic substitution reaction supported by multi-metals Add 50 mg of the porous nitrogen-doped carbon nanomaterial-loaded Co NPs composite material obtained in step (2) to 50 mL of water and ultrasonically disperse for 30 min; then add each metal source (FeCl3, CuCl2, RuCl3·xH2O and NaPtCl6, each amount 19.2 µmol) and ultrasonically disperse for 30 min; stir at 80 °C for 12 h in an oil bath, centrifuge, wash, and dry to obtain the intermediate composite material, i.e. the precursor composite material; (4) Thermally induced alloying forms high-entropy alloys The intermediate composite material was placed in a pyrolysis apparatus and heated from room temperature to the target temperature of 400℃ at a heating rate of 2℃ / min under a protective gas atmosphere (H2 / Ar mixed gas, with H2 accounting for 5% of the volume). The temperature was then held at this temperature for 2 hours and subsequently cooled naturally to room temperature to obtain high-entropy alloy nanozymes (HEA nanozyme materials).

[0049] Comparative Example 1 Comparative Example 1 provides a CoFeCu ternary alloy catalyst, the preparation process of which is as follows: (1) Preparation of 3D ZIF-67, same as in Example 1; (2) Pyrolysis preparation of porous nitrogen-doped carbon nanomaterials loaded with Co NPs composite material, same as in Example 1; (3) Galvanic substitution reaction supported on multi-metals 50 mg of porous nitrogen-doped carbon nanomaterials loaded with Co NPs were weighed and dispersed in 50 mL of water and ultrasonically dispersed for 30 min. 48 µmol of FeCl3 and 48 µmol of CuCl2 were added and ultrasonically dispersed for 30 min. The mixture was stirred and reacted at 80 °C in an oil bath for 12 h. After centrifugation, washing, and drying, the intermediate composite material was obtained. (4) Thermally induced alloying The intermediate composite material obtained in step (3) was placed in a tube furnace and heated to 400°C at 2°C / min under a nitrogen atmosphere. The temperature was held for 2 hours and then cooled to obtain the CoFeCu ternary alloy catalyst (LEA nanoenzyme material).

[0050] Comparative Example 2 Comparative Example 2 provides a MEA nanozyme material, the preparation process of which is as follows: (1) Preparation of 3D ZIF-67, same as in Example 1; (2) Pyrolysis preparation of Co NPs support, same as in Example 1; (3) Galvanic substitution reaction supported by multi-metals 50 mg of porous nitrogen-doped carbon nanomaterials loaded with Co NPs were weighed and dispersed in 50 mL of water and ultrasonically dispersed for 30 min. Then FeCl3, CuCl2 and RuCl3·xH2O (36 µmol each) were added and ultrasonically dispersed for 30 min. The mixture was stirred and reacted at 80 °C in an oil bath for 12 h. After centrifugation, washing and drying, the intermediate composite material was obtained. (4) Thermally induced alloying The intermediate composite material obtained in step (3) was placed in a tube furnace and heated to 400°C at 2°C / min under a nitrogen atmosphere. The temperature was maintained for 2 hours and then cooled to obtain MEA nanoenzyme material.

[0051] Performance testing 1. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and particle size distribution testing. Scanning electron microscopy was performed on the ZIF-67 composite material prepared in Example 1, which is a porous nitrogen-doped carbon nanomaterial loaded with Co NPs. The results are as follows: Figure 1 and 2 As shown.

[0052] Depend on Figure 1 and Figure 2 It can be seen that ZIF-67 exhibits a dodecahedral structure with uniform size. Furthermore, after pyrolysis, Co NPs are uniformly dispersed on the carbon support, which is very stable and does not collapse, providing a foundation for subsequent galvanic substitution reactions to support multi-metal components.

[0053] The high-entropy alloy nanozyme prepared in Example 1 was subjected to scanning electron microscopy, transmission electron microscopy, and particle size distribution testing. The results are as follows: Figure 3 As shown. Among them, Figure 3 Figure a in the image is a scanning electron microscope image, with a scale bar of 100 nm. Figure 3 Image b in the image is a transmission electron microscope (TEM) image, with a scale bar of 50 nm. Figure 3 Figure c in the diagram is the particle size distribution.

[0054] Depend on Figure 3 It can be seen that HEA nanozyme material was successfully prepared, with uniform size and no aggregation.

[0055] Transmission electron microscopy and particle size distribution tests were performed on the MEA nanozyme material prepared in Comparative Example 2 and the LEA nanozyme material prepared in Comparative Example 1. The results are as follows: Figure 4 and Figure 5 As shown. Among them, Figure 4 Figure (a) shows a transmission electron microscope image of the MEA nanozyme material. Figure 4 (b) in the figure is the particle size distribution diagram of MEA nanozyme material; Figure 5 Figure (a) in the image is a transmission electron microscope image of the LEA nanozyme material. Figure 5 Figure (b) shows the particle size distribution of the LEA nanozyme material.

[0056] Depend on Figure 4 , 5 It can be seen that both LEA and MEA nanozyme materials are larger in size than HEA nanozyme materials. Smaller size means larger specific surface area, which is more conducive to performance improvement.

[0057] 2. Pesticide residue testing The specific process for pesticide residue testing is as follows: Preparation of the reaction system: A certain amount of the high-entropy alloy nanozyme from Example 1 was dispersed in an acetate-sodium acetate buffer solution with a pH of 3.5 to prepare a nanozyme dispersion with a concentration of 0.18 mg / mL; 8 μL (5 mg / mL) of the above high-entropy alloy nanozyme dispersion and 4 μL of TMB solution (concentration of 1 mM) were measured into a reaction vessel and mixed evenly to form a reaction system; Blank group detection: After the above reaction system is reacted at room temperature, its absorbance is measured at 652 nm using a UV-Vis spectrophotometer and recorded as A0; Detection of pesticide residues: Add a certain amount of pesticide residue sample (0.1-100 μmol of zinc thiram solution) to another reaction system identical to the one described above. After reacting under the same conditions, measure the absorbance at 652 nm and record it as A1.

[0058] The pesticide residue detection results of the high-entropy alloy nanozyme in Example 1 are as follows: Figure 6 As shown, where, Figure 6 The highest line in the spectrum represents absorbance A0, and the rest represent absorbance A1.

[0059] Depend on Figure 6 The detection results showed that the blank reaction system had a significant ultraviolet absorption peak at 652 nm (high absorbance A0 value), while the absorption peak at 652 nm of the reaction system after adding pesticide residues decreased significantly (A1 is much smaller than A0). This indicates that the HEA nanozyme material prepared by pyrolysis possesses oxidase, which can catalyze the generation of free radicals from oxygen and then oxidize TMB. The presence of pesticide residues causes a change in the absorbance of the reaction system, thus enabling the detection of pesticide residues.

[0060] Furthermore, using conventional methods in this field, a detection method for zinc thiram was established, and a standard curve was fitted to obtain the detection equation Y = 1.8625 - 0.0168x, with a correlation coefficient R. 2 =0.994, the fitting curve for the detection of zinc thiram is as follows: Figure 7 As shown. By Figure 7 It is evident that the linear relationship is excellent and the detection accuracy is high; its detection limit is 0.005µM, and its sensitivity is excellent, enabling precise quantification of thiram zinc, meeting the detection needs of low-content thiram zinc, and demonstrating strong technical practicality and broad application prospects.

[0061] The system after the addition of pesticide residues was tested using infrared spectroscopy and Raman spectroscopy, and the results are as follows: Figure 8 As shown. Among them, Figure 8 Figure (a) in the image is an infrared spectrum. Figure 8 Figure (b) in the image is a Raman spectrum.

[0062] Depend on Figure 8 It can be seen that the sulfur element in zinc thiram and the metal element in HEA form MS bonds, which leads to a decrease in performance and enables the detection of zinc thiram.

[0063] 3. Methylene Blue (MB) Degradation Test A certain amount of the high-entropy alloy nanozyme from Example 1 was dispersed in a buffer solution (acetic acid-sodium acetate buffer solution with pH=4) to prepare a nanozyme dispersion with a concentration of 0.16 mg / mL. 0.16 mg / mL of this nanozyme dispersion and 6 μL of H2O2 (concentration 1.5 mM) were measured into a reaction vessel, MB was added, and then the absorbance was measured. A decrease in absorbance indicated that MB degradation could be achieved.

[0064] Example 1: The degradation effect of high-entropy alloy nanoenzymes on methylene blue is as follows: Figure 9 As shown.

[0065] Depend on Figure 9 It can be seen that the degradation rate of MB by high-entropy alloy nanozymes is as high as 90% within 40 minutes, which indicates that high-entropy alloy nanozymes have highly efficient peroxidase activity.

[0066] 4. Peroxidase activity test The oxidase activities of the high-entropy alloy nanozyme of Example 1, the LEA nanozyme material of Comparative Example 1, and the MEA nanozyme material of Comparative Example 2 were tested. The test method is as follows: A certain amount of LEA nanozyme was dispersed in an acetate-sodium acetate buffer solution with a pH of 3.5 to prepare a nanozyme dispersion with a concentration of 0.18 mg / mL; 8 μL (5 mg / mL) of the above LEA nanozyme dispersion and 4 μL of TMB solution (concentration of 1 mM) were measured in a reaction vessel, mixed evenly to form a reaction system, and the oxidase activity of LEA was tested. The tests for the high-entropy alloy nanozyme and MEA nanozyme material were performed in the same manner.

[0067] The results of the comparison of oxidase activities of high-entropy alloy nanozyme (Example 1), LEA nanozyme material (Comparative Example 1), MEA nanozyme material (Comparative Example 2), and TMB are as follows: Figure 10 As shown in the figure. Curve a represents the oxidase activity of the chromogenic agent TMB, curve b represents the oxidase activity of LEA nanozyme material + TMB, curve c represents the oxidase activity of MEA nanozyme material + TMB, and curve d represents the oxidase activity of HEA nanozyme material + TMB.

[0068] Depend on Figure 10 It can be seen that the HEA nanozyme material has the highest absorbance, indicating that its oxidation performance is the best.

[0069] 5. Peroxidase activity test The peroxidase activity of the high-entropy alloy nanozyme of Example 1, the LEA nanozyme material of Comparative Example 1, and the MEA nanozyme material of Comparative Example 2 was tested. The test method is as follows: A certain amount of LEA nanozyme was dispersed in an acetate-sodium acetate buffer solution with a pH of 4.0 to prepare a nanozyme dispersion with a concentration of 0.18 mg / mL; 10 μL (5 mg / mL) of the above LEA nanozyme dispersion, 3 μL of H2O2 (0.15 mM) and 3 μL of TMB solution (concentration of 1 mM) were measured in a reaction vessel, mixed evenly to form a reaction system, and the peroxidase activity of LEA was tested. The testing of the high-entropy alloy nanozyme and MEA nanozyme material was the same as above.

[0070] The peroxidase activity comparison results of the high-entropy alloy nanozyme of Example 1, the LEA nanozyme material of Comparative Example 1, and the MEA nanozyme material of Comparative Example 2 are as follows: Figure 11 As shown in the figure, curve a represents the peroxidase activity of the chromogenic agent TMB, curve b represents the peroxidase activity of H2O2, curve c represents the peroxidase activity of the chromogenic agent TMB + H2O2, curve d represents the peroxidase activity of LEA nanozyme material + TMB + H2O2, curve e represents the peroxidase activity of MEA nanozyme material + TMB + H2O2, and curve f represents the peroxidase activity of HEA nanozyme material + TMB + H2O2.

[0071] Depend on Figure 11 It can be seen that the absorbance of HEA high-entropy alloy nanozyme is the highest, indicating that its peroxidase activity is the best.

[0072] 6. Stability Test The performance stability of the high-entropy alloy nanozyme prepared in Example 1 was tested. The specific test procedure is as follows: A certain amount of HEA nanozyme material was dispersed in an acetate-sodium acetate buffer solution with pH=4.0 to prepare a nanozyme dispersion with a concentration of 0.18 mg / mL; 10 μL (5 mg / mL) of the above LEA nanozyme dispersion, 3 μL of H2O2 (0.15 mM) and 3 μL of TMB solution (concentration of 1 mM) were measured in a reaction vessel, mixed evenly to form a reaction system, and the absorbance was measured at 652 nm to test the stability of the HEA nanozyme material.

[0073] The stability test results of high-entropy alloy nanozymes in Example 1 are as follows: Figure 12 As shown, where, Figure 12 Figure (a) shows the stability results after 30 days, with absorbance measured at 5-day intervals. Figure 12 Figure (b) shows the results of the stability test after eight consecutive scans.

[0074] Depend on Figure 12It can be seen that the HEA nanozyme material has good stability, laying the foundation for subsequent degradation and detection.

[0075] In summary, this invention constructs a highly efficient dual-enzyme high-entropy alloy sensing platform using nitrogen-doped carbon nanomaterials and high-entropy alloys, exhibiting both oxidase and peroxidase activities. Utilizing its oxidase activity in reaction with a chromogenic agent, and by referencing changes in the UV absorption peak at 652 nm, pesticide residues can be detected. This method offers simple operation, low cost, and high sensitivity; the detection limit of this invention can achieve pesticide residue detection as low as 0.005 μmol, far below the detection limits of existing pesticide residue detection technologies. Simultaneously, in the presence of H₂O₂, the high-entropy alloy nanozyme and H₂O₂ generate free radicals, which can degrade the organic dye MB.

[0076] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A high-entropy alloy nanozyme, characterized in that, The high-entropy alloy nanoenzyme comprises nitrogen-doped carbon nanomaterials and a high-entropy alloy; the high-entropy alloy is loaded on the nitrogen-doped carbon nanomaterials.

2. The high-entropy alloy nanoenzyme according to claim 1, characterized in that, The high-entropy alloy includes Co, Fe, Cu, Ru, and Pd.

3. The method for preparing the high-entropy alloy nanozyme according to any one of claims 1-2, characterized in that, The preparation method includes the following steps: (1) The ZIF-67 material was pyrolyzed to obtain a composite material of nitrogen-doped carbon nanomaterials loaded with cobalt nanoparticles; (2) The nitrogen-doped carbon nanomaterials loaded with cobalt nanoparticles obtained in step (1) are mixed with a metal salt and reacted to obtain a precursor composite material. (3) The precursor composite material is subjected to pyrolysis treatment to obtain the product.

4. The preparation method according to claim 3, characterized in that, In step (1), the preparation method of the ZIF-67 material includes the following steps: mixing cobalt salt and 2-methylimidazole with solvent, reacting, and obtaining the material.

5. The preparation method according to claim 3, characterized in that, In step (1), the temperature of the pyrolysis treatment is 500-700℃, and the holding time of the pyrolysis treatment is 1.5-2.5h.

6. The preparation method according to claim 4, characterized in that, In the preparation process of the ZIF-67 material, the molar ratio of the cobalt salt and 2-methylimidazole is 1:(3-5). And / or, the cobalt salt comprises Co(NO3)2·6H2O; And / or, the reaction time is 2-4 hours.

7. The preparation method according to claim 3, characterized in that, In step (2), the metal salt includes Fe salt, Cu salt, Ru salt and Pd salt; And / or, in step (2), the reaction time is 11-13 h.

8. The preparation method according to claim 7, characterized in that, In step (2), the ratio of the nitrogen-doped carbon nanomaterial-supported cobalt nanoparticle composite material to any one of Fe salt, Cu salt, Ru salt and Pd salt is 50 mg: (18-20) µmol. And / or, in the metal salt, the molar ratio of the Fe salt, Cu salt, Ru salt and Pd salt is (0.8-1.2):(0.8-1.2):(0.8-1.2)1; And / or, the Fe salt includes FeCl3; And / or, the Cu salt includes CuCl2; And / or, the Ru salt comprises RuCl3·xH2O; And / or, the Pd salt includes NaPtCl6.

9. The preparation method according to claim 3, characterized in that, In step (3), the temperature of the pyrolysis treatment is 300-500℃, and the holding time of the pyrolysis treatment is 1.5-2.5h.

10. The application of the high-entropy alloy nanozyme according to any one of claims 1-2 in pesticide residue detection and organic pollutant degradation.

Images