Enzyme-free glucose sensor electrode based on trimetallic sulfide and preparation method and application thereof

Abstract

This invention belongs to the field of electrochemical biosensing technology, and discloses an enzyme-free glucose sensor electrode based on a trimetallic sulfide, its preparation method, and its application. The electrode comprises a copper foam substrate and a cobalt-nickel-copper trimetallic sulfide (CoS-NiS-Cu) loaded on the surface of the copper foam substrate. x S), multi-walled carbon nanotubes, and gold nanomaterials. Preparation methods include: preparing cobalt-nickel-copper trimetallic sulfides (CoS-NiS-Cu) on copper foam (CF) using a continuous ion layer reaction and adsorption (SILAR) method. x S), then multi-walled carbon nanotube (MWCNT) dispersion is added dropwise. Metal sulfides are prepared on copper foam and MWCNTs using SILAR. MWCNT dispersion is then added dropwise again, and finally, a gold nanoparticle dispersion is added dropwise to obtain a gold / MWCNT / cobalt-nickel-copper trimetallic sulfide / copper foam electrode (Au / MWCNTs / CoS-NiS-Cu). x The enzyme-free glucose sensor electrode prepared by the method of this invention has the advantages of wide linear range, high sensitivity, good stability and high selectivity, and has good application prospects in blood glucose detection.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical biosensing technology, and relates to an enzyme-free glucose sensor for qualitative and quantitative detection of glucose, and particularly to an enzyme-free glucose sensor electrode based on trimetallic sulfides, its preparation method and application. Background Technology

[0002] Diabetes seriously threatens human health, and its diagnosis and treatment have always been major challenges in the medical field. Accurate measurement of blood glucose levels in diabetic patients allows for effective monitoring and treatment. Glucose electrochemical sensors are divided into enzyme-based and enzyme-free types. However, enzyme activity is easily affected by the external environment, limiting the application of enzyme sensors. Currently, enzyme-free glucose electrochemical sensors overcome the shortcomings of enzyme sensors and are gradually becoming a research hotspot. Developing an enzyme-free electrochemical glucose sensor electrode with high selectivity, a wide linear range, and high sensitivity is of great significance.

[0003] Transition metals copper, cobalt, nickel, and their compounds (oxides, sulfides, hydroxides, etc.) are often used as non-enzymatic catalysts for glucose oxidation due to their excellent catalytic activity. For example, patent CN109239150A discloses a porous Co3O4 nanosheet non-enzymatic glucose sensor and its preparation method, achieving high sensitivity. Another example is CN103454328A, which discloses a Cu-based CuO thin-film electrode for glucose detection. The CuO film is grown in situ on the surface of a Cu substrate, exhibiting good adhesion to the substrate material and enhancing its stability. However, research has found that the electrochemical performance of glucose sensors based on a single metal still has certain shortcomings. Therefore, it is necessary to study non-enzymatic electrochemical glucose sensors based on two or more metals to improve electrochemical performance by utilizing the synergistic effect between different metals.

[0004] For example, patent CN106290517A discloses a method for preparing a highly sensitive enzyme-free glucose sensor electrode material. This method involves interleaving and supporting cobalt hydroxide nanosheets and copper nanoparticles on a conductive substrate to form a multi-level structure containing cobalt hydroxide nanosheets and copper nanoparticles. Another example is patent CN113447552A, which discloses a method for preparing an enzyme-free glucose electrochemical sensor. This method uses copper foam as a substrate and a copper source, employing an ion-layer adsorption and reaction method to prepare a copper-cobalt-nickel composite sulfide. Although the synergistic effect of the three metals (cobalt and nickel) gives it good catalytic performance and achieves high sensitivity, the use of water as a solvent in the ion-layer adsorption and reaction method, coupled with the relatively poor conductivity of the transition metal sulfide, results in a narrow linear range for the sensor, requiring further improvement. Summary of the Invention

[0005] The purpose of this invention is to address the technical deficiencies of existing non-enzymatic electrochemical glucose sensors by providing a non-enzymatic glucose sensor electrode based on trimetallic sulfides, its preparation method, and its application.

[0006] The present invention provides a method for preparing an enzyme-free glucose sensor electrode, which modifies the surface of copper foam with cobalt-nickel-copper trimetallic sulfides, MWCNTs, and gold nanoparticles. Due to its advantages of high catalytic activity, large specific surface area, and excellent conductivity, an electrochemical sensor electrode with a wide linear range, low detection limit, good stability, and high sensitivity is prepared for the qualitative and quantitative detection of glucose.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The first aspect of the present invention is to provide an enzyme-free glucose sensor electrode based on a trimetallic sulfide, the electrode comprising a copper foam substrate and a cobalt-nickel-copper trimetallic sulfide (CoS-NiS-Cu) loaded on the surface of the copper foam substrate. x S), multi-walled carbon nanotubes and gold nanomaterials.

[0009] Preferably, the cobalt-nickel-copper trimetallic sulfide (CoS-NiS-Cu) x Cu in S) x S is obtained using copper foam as the copper source and only adheres to the surface of the copper foam, while cobalt-nickel-copper trimetallic sulfides (CoS-NiS-Cu) x CoS-NiS in S) not only adheres to the surface of copper foam, but also to multi-walled carbon nanotubes, so that the multi-walled carbon nanotubes are wrapped in nanoflowers formed by the aggregation of 20-30nm CoS-NiS nanoparticles.

[0010] Preferably, the surface of the foamed copper is coated with the cobalt-nickel-copper trimetallic sulfide (CoS-NiS-Cu). x S), the multi-walled carbon nanotubes are modified on the electrode in two layers. The first layer of multi-walled carbon nanotubes is modified on the pre-loaded cobalt-nickel-copper trimetallic sulfide, which serves as a support for the second SILAR-grown CoS-NiS nanoparticles. The second layer of multi-walled carbon nanotubes is modified on the multi-walled carbon nanotube layer loaded with CoS-NiS nanoparticles. Finally, the gold nanomaterial is loaded onto the modified electrode surface.

[0011] A second aspect of the present invention is to provide a method for preparing an enzyme-free glucose sensor electrode based on a trimetallic sulfide, comprising the following steps:

[0012] (1) Add sodium citrate solution and polyvinylpyrrolidone solution to HAuCl4 solution, heat and stir to obtain a gold nanoparticle dispersion;

[0013] (2) Disperse MWCNTs (multi-walled carbon nanotubes) in a mixed solution of perfluorinated resin (Nafion) and ethanol, and mix them evenly by ultrasonication to obtain MWCNTs dispersion.

[0014] (3) Immerse copper foam (CF) in a methanol aqueous solution of cobalt sulfate and nickel sulfate for a certain period of time to remove excess ions, and then immerse it in a methanol aqueous solution of sodium sulfide for a certain period of time to remove excess ions. That is, cobalt-nickel-copper trimetallic sulfide (CoS-NiS-Cu) is generated on the copper foam through the continuous ion layer reaction and adsorption method (SILAR). x S), yielding CoS-NiS-Cu x S / CF electrode;

[0015] (4) The CoS-NiS-Cu obtained in step (3) x The MWCNTs dispersion obtained in step (2) was dropped onto the S / CF electrode and dried.

[0016] (5) Repeat steps (3) to (4) once to dry;

[0017] (6) The nano-gold dispersion from step (1) is dropped onto the electrode obtained in step (5), and after drying, a gold / multi-walled carbon nanotube / cobalt-nickel-copper trimetallic sulfide / foamed copper electrode (Au / MWCNTs / CoS-NiS-Cu) is obtained. x S / CF).

[0018] Preferably, in step (1), the concentration of the gold nanoparticle dispersion is 0.0239-0.0717 mg / mL and the particle size is 1-5 nm.

[0019] Preferably, in step (2), the length of the MWCNTs (multi-walled carbon nanotubes) is 10-30 μm and the outer diameter is 20-30 nm;

[0020] The concentration of the Nafion solution was 5% (w / w), the volume ratio of Nafion solution to ethanol was 1:9, and the concentration of the obtained MWCNTs dispersion was 1-2 mg / mL.

[0021] Preferably, in step (3), the volume ratio of methanol to water in the methanol-water solution of cobalt sulfate and nickel sulfate is 0.5-1.5:4, and the immersion time is 6-14s.

[0022] The concentration of the CoSO4-NiSO4 solution is 0.05-0.15M, the cobalt-nickel molar ratio is 2-4:1, and the concentration of the Na2S solution is 0.15-0.25M.

[0023] More preferably, in step (3), the volume ratio of methanol to water in the methanol-water solution of cobalt sulfate and nickel sulfate is 1:4, and the immersion time is 10s.

[0024] The concentration of the CoSO4-NiSO4 solution is 0.1M, the molar ratio of cobalt to nickel is 3:1, and the concentration of the Na2S solution is 0.2M.

[0025] Preferably, in step (4), the coating amount of the MWCNTs dispersion is 0.075-0.15 mg / cm³. 2 The drying temperature is 50-60℃, and the drying time is 0.5-1.5h.

[0026] Preferably, in step (6), the coating amount of the gold nanoparticle dispersion is 1.195-1.7925 μg / cm³. 2 The drying temperature is 50℃ and the drying time is 3 hours.

[0027] A third aspect of the present invention is to provide an application of an enzyme-free glucose sensor electrode as described above and / or an enzyme-free glucose sensor electrode prepared by the method described above in the fabrication of a glucose sensor.

[0028] The fabricated enzyme-free glucose sensor based on trimetallic sulfides was applied to the qualitative and quantitative detection of glucose.

[0029] The present invention adopts the above technical solution and has the following technical effects compared with the prior art:

[0030] 1) This invention uses CoS-NiS-Cu x S, MWCNTs, and nano-gold modified copper foam: Copper foam is not only a substrate material with large specific surface area and good conductivity, but also an in-situ grown Cu. x S is derived from copper; trimetallic sulfides CoS-NiS-Cu x S grows in situ on copper foam, which has good contact with the substrate and increases the catalytic activity of the electrode. MWCNTs are layered and modified on the electrode, which not only increases the specific surface area and conductivity of the electrode, but also grows CoS-NiS nanoparticles in situ, which are in close contact with metal sulfides, thus increasing the catalytic activity of the electrode. Gold nanoparticles improve the conductivity and catalytic performance of the electrode, so that the prepared electrode has a good effect on the catalytic oxidation of glucose.

[0031] 2) The enzyme-free glucose sensor electrode of the present invention is modified on the surface of copper foam with cobalt-nickel-copper trimetallic sulfide, MWCNTs and nano gold. Its preparation method is simple, the conditions are mild, and the whole process does not involve medium and high temperature heat treatment. It is energy-saving and environmentally friendly, with low production cost, and is suitable for large-scale production.

[0032] 3) The enzyme-free glucose sensor electrode prepared in this invention reacts rapidly to glucose solution, with a linear range of 0.01-9 mM, a detection limit of 7.5 μM, and a sensitivity of 936.25 μA·mM. -1 ·cm -2 It also has good stability and anti-interference performance. Attached Figure Description

[0033] Figure 1 This is a scanning electron microscope image of the sensor electrode provided in Example 1.

[0034] Figure 2 The image shows the energy spectrum of the sensor electrode provided in Example 1.

[0035] Figure 3 The X-ray photoelectron spectra of the sensor electrodes provided in Example 1 are shown below; where (a) is the full XPS spectrum, (b) is the Ni2p, (c) is the Co2p, (d) is the Cu2p, and (e) is the S2p XPS spectrum.

[0036] Figure 4 Transmission electron microscopy (TEM) images of the sensor electrode material (a) and the gold nanomaterial (b) provided in Example 1.

[0037] Figure 5 The graph shows the cyclic voltammetry curves of the sensor electrode provided in Example 1 with and without glucose.

[0038] Figure 6 The graphs shown are (a) cyclic voltammetry curves of the sensor electrode provided in Example 1 at different scan rates, and (b) the graphs showing the relationship between the anode peak current density and the cathode peak current density and the scan rate.

[0039] Figure 7 The graphs shown in Example 1 are: time-current density curves (a) for the sensor electrode detecting the continuous addition of different concentrations of glucose, and a graph showing the linear relationship between glucose concentration and current density (b).

[0040] Figure 8 The image shows the time-current density response of the sensor electrode provided in Example 1 to different interfering objects.

[0041] Figure 9 The sensor electrode provided in Example 1 detects the current density value of 0.5 mM glucose at different times.

[0042] Figure 10 The cyclic voltammetry curves of the five parallel sensor electrodes provided in Example 1 in 0.5 mM glucose are shown.

[0043] Figure 11Cyclic voltammetry curves of CF and electrodes of Examples 1, 10, and 13 in 0.5 mM glucose. Detailed Implementation

[0044] The present invention will now be described in detail and specifically through specific embodiments to enable a better understanding of the invention. However, the following embodiments do not limit the scope of the invention.

[0045] Example 1: Preparation of an enzyme-free glucose sensor electrode

[0046] (1) Add 50 mL of 0.01% HAuCl4 to a three-necked flask, stir continuously and heat to boiling, then add 1.7 mL of 1% sodium citrate solution and 0.5 mL of 1% PVP solution to the three-necked flask in sequence, continue heating for 30 min, then stop and cool to room temperature to prepare a nano-gold dispersion with a concentration of 0.0478 mg / mL;

[0047] (2) Weigh 0.0015 g of MWCNTs (length 10-30 μm, outer diameter 20-30 nm) powder, and make up to 1 mL with a mixture of Nafion solution (5% w / w) and ethanol (the volume ratio of Nafion solution to ethanol is 1:9). Disperse the mixture by sonication for 10 min to obtain a MWCNTs dispersion with a concentration of 1.5 mg / mL.

[0048] (3) Immerse the copper foam in a 0.1M CoSO4-NiSO4 solution (0.21g CoSO4·7H2O and 0.065g NiSO4·6H2O, diluted to 10mL with a 1:4 volume ratio of methanol and water) for 10s, rinse with deionized water to remove excess ions, and then immerse it in a 0.2M Na2S solution (0.48g Na2S·9H2O, diluted to 10mL with a 1:4 volume ratio of methanol and water) for 10s, rinse with deionized water to remove excess ions, and you will get CoS-NiS-Cu. x S / CF electrode;

[0049] (4) Take 60 μL of 1.5 mg / mL MWCNTs dispersion and uniformly drop it onto CoS-NiS-Cu. x The coating area on the S / CF electrode surface is 0.8 cm². 2 Dry at 50℃ for 1 hour;

[0050] (5) Repeat steps (3)-(4) once;

[0051] (6) Take 20 μL of 0.0478 mg / mL gold nanoparticle dispersion and coat it evenly onto the electrode obtained in step (5), with a coating area of ​​0.8 cm². 2The final electrode was obtained by drying at 50℃ for 3 hours and labeled as (Au / MWCNTs / CoS-NiS-Cu). x S / CF)1.

[0052] Example 2: Preparation of an enzyme-free glucose sensor electrode

[0053] (1) Add 50 mL of 0.005% HAuCl4 to a three-necked flask, stir continuously and heat to boiling, then add 1.7 mL of 1% sodium citrate solution and 0.5 mL of 1% PVP solution to the three-necked flask in sequence, continue heating for 30 min, then stop and cool to room temperature to prepare a nano-gold dispersion with a concentration of 0.0239 mg / mL;

[0054] (2) Weigh 0.001 g of MWCNTs (length 10-30 μm, outer diameter 20-30 nm) powder, and make up to 1 mL with a mixture of Nafion solution (5% w / w) and ethanol (the volume ratio of Nafion solution to ethanol is 1:9). Disperse the mixture by sonication for 10 min to obtain a MWCNTs dispersion with a concentration of 1.0 mg / mL.

[0055] (3) Immerse the copper foam in a 0.1M CoSO4-NiSO4 solution (0.21g CoSO4·7H2O and 0.065g NiSO4·6H2O, diluted to 10mL with a 1:4 volume ratio of methanol and water) for 10s, rinse with deionized water to remove excess ions, and then immerse it in a 0.2M Na2S solution (0.48g Na2S·9H2O, diluted to 10mL with a 1:4 volume ratio of methanol and water) for 10s, rinse with deionized water to remove excess ions, and you will get CoS-NiS-Cu. x S / CF electrode;

[0056] (4) Take 60 μL of 1.0 mg / mL MWCNTs dispersion and uniformly drop it onto CoS-NiS-Cu. x The coating area on the S / CF electrode surface is 0.8 cm². 2 Dry at 50℃ for 1 hour;

[0057] (5) Repeat steps (3)-(4) once;

[0058] (6) Take 20 μL of 0.0239 mg / mL gold nanoparticle dispersion and coat it evenly onto the electrode obtained in step (5), with a coating area of ​​0.8 cm². 2 The final electrode was obtained by drying at 50℃ for 3 hours and labeled as (Au / MWCNTs / CoS-NiS-Cu). x S / CF)2.

[0059] Example 3: Preparation of an enzyme-free glucose sensor electrode

[0060] (1) Add 50 mL of 0.015% HAuCl4 to a three-necked flask, stir continuously and heat to boiling, then add 1.7 mL of 1% sodium citrate solution and 0.5 mL of 1% PVP solution to the three-necked flask in sequence, continue heating for 30 min, then stop, cool to room temperature, and prepare a nano gold dispersion with a concentration of 0.0717 mg / mL;

[0061] (2) Weigh 0.002 g of MWCNTs (length 10-30 μm, outer diameter 20-30 nm) powder, and make up to 1 mL with a mixture of Nafion solution (5% w / w) and ethanol (the volume ratio of Nafion solution to ethanol is 1:9). Disperse the mixture by sonication for 10 min to obtain a MWCNTs dispersion with a concentration of 2.0 mg / mL.

[0062] (3) Immerse the copper foam in a 0.1M CoSO4-NiSO4 solution (0.21g CoSO4·7H2O and 0.065g NiSO4·6H2O, diluted to 10mL with a 1:4 volume ratio of methanol and water) for 10s, rinse with deionized water to remove excess ions, and then immerse it in a 0.2M Na2S solution (0.48g Na2S·9H2O, diluted to 10mL with a 1:4 volume ratio of methanol and water) for 10s, rinse with deionized water to remove excess ions, and you will get CoS-NiS-Cu. x S / CF electrode;

[0063] (4) Take 60 μL of 2.0 mg / mL MWCNTs dispersion and uniformly drop it onto CoS-NiS-Cu. x The coating area on the S / CF electrode surface is 0.8 cm². 2 Dry at 50℃ for 1 hour;

[0064] (5) Repeat steps (3)-(4) once;

[0065] (6) Take 20 μL of 0.0717 mg / mL gold nanoparticle dispersion and coat it evenly onto the electrode obtained in step (5), with a coating area of ​​0.8 cm². 2 The final electrode was obtained by drying at 50℃ for 3 hours and labeled as (Au / MWCNTs / CoS-NiS-Cu). x S / CF)3.

[0066] Example 4: Preparation of an enzyme-free glucose sensor electrode

[0067] In Example 4, step (5) is repeated 0 times from step (3) to step (4). The remaining steps are the same as in Example 1, and the final electrode is labeled (Au / MWCNTs / CoS-NiS-Cu). x S / CF)4.

[0068] Example 5: Preparation of an enzyme-free glucose sensor electrode

[0069] In Example 5, step (5) is repeated twice with steps (3)-(4). The remaining steps are the same as in Example 1, and the final electrode is labeled (Au / MWCNTs / CoS-NiS-Cu). x S / CF)5.

[0070] Example 6: Preparation of an enzyme-free glucose sensor electrode

[0071] In Example 6, the concentration of the CoSO4-NiSO4 solution used in step (3) was 0.05 M (Co / Ni molar ratio was 3:1, and the volume ratio of methanol to water was 1:4), and the concentration of the Na2S solution used was 0.15 M (methanol to water volume ratio was 1:4). The remaining steps were the same as in Example 1, and the final electrode was labeled (Au / MWCNTs / CoS-NiS-Cu). x S / CF)6.

[0072] Example 7: Preparation of an enzyme-free glucose sensor electrode

[0073] In Example 7, the concentration of the CoSO4-NiSO4 solution used in step (3) was 0.15M (Co / Ni molar ratio was 3:1, and the volume ratio of methanol to water was 1:4), and the concentration of the Na2S solution used was 0.25M (methanol to water volume ratio was 1:4). The remaining steps were the same as in Example 1, and the final electrode was labeled (Au / MWCNTs / CoS-NiS-Cu). x S / CF)7.

[0074] Example 8

[0075] In step (3) of Example 8, the concentration of the CoSO4-NiSO4 solution used was 0.1M (Co / Ni molar ratio was 2:1, and the volume ratio of methanol to water was 1:4), and the concentration of the Na2S solution used was 0.2M (methanol to water volume ratio was 1:4). The remaining steps were the same as in Example 1, and the final electrode was labeled (Au / MWCNTs / CoS-NiS-Cu). x S / CF)8.

[0076] Example 9

[0077] In Example 9, the concentration of the CoSO4-NiSO4 solution used in step (3) was 0.1 M (Co / Ni molar ratio was 4:1, and the volume ratio of methanol to water was 1:4), and the concentration of the Na2S solution used was 0.2 M (methanol to water volume ratio was 1:4). The remaining steps were the same as in Example 1, and the final electrode was labeled (Au / MWCNTs / CoS-NiS-Cu). x S / CF)9.

[0078] Example 10: Preparation of an enzyme-free glucose sensor electrode

[0079] (1) Weigh 0.0015 g of MWCNTs (length 10-30 μm, outer diameter 20-30 nm) powder, and make up to 1 mL with a mixture of Nafion solution (5% w / w) and ethanol (the volume ratio of Nafion solution to ethanol is 1:9). Disperse the mixture by sonication for 10 min to obtain a MWCNTs dispersion with a concentration of 1.5 mg / mL.

[0080] (2) Immerse the copper foam in a 0.1M CoSO4-NiSO4 solution (0.21g CoSO4·7H2O and 0.065g NiSO4·6H2O, diluted to 10mL with a 1:4 volume ratio of methanol and water) for 10s, rinse with deionized water to remove excess ions, and then immerse it in a 0.2M Na2S solution (0.48g Na2S·9H2O, diluted to 10mL with a 1:4 volume ratio of methanol and water) for 10s, rinse with deionized water to remove excess ions, thus obtaining CoS-NiS-Cu. x S / CF electrode;

[0081] (3) Take 60 μL of 1.5 mg / mL MWCNTs dispersion and uniformly drop it onto CoS-NiS-Cu. x The coating area on the S / CF electrode surface is 0.8 cm². 2 Dry at 50℃ for 1 hour;

[0082] (4) Repeat steps (3)-(4) once to obtain the final electrode, labeled as MWCNTs / CoS-NiS-Cu. x S / CF.

[0083] Example 11: Preparation of an enzyme-free glucose sensor electrode

[0084] (1) Add 50 mL of 0.01% HAuCl4 to a three-necked flask, stir continuously and heat to boiling, then add 1.7 mL of 1% sodium citrate solution and 0.5 mL of 1% PVP solution to the three-necked flask in sequence, continue heating for 30 min, then stop and cool to room temperature to prepare a nano-gold dispersion with a concentration of 0.0478 mg / mL;

[0085] (2) Weigh 0.0015 g of MWCNTs (length 10-30 μm, outer diameter 20-30 nm) powder, and make up to 1 mL with a mixture of Nafion solution (5% w / w) and ethanol (the volume ratio of Nafion solution to ethanol is 1:9). Disperse the mixture by sonication for 10 min to obtain a MWCNTs dispersion with a concentration of 1.5 mg / mL.

[0086] (3) Immerse the copper foam in 0.2M Na2S solution (0.48g Na2S·9H2O, diluted to 10mL with a 1:4 volume ratio of methanol and water) for 10s, then rinse with deionized water to remove excess ions, thus obtaining Cu. x S / CF electrode;

[0087] (4) Take 60 μL of 1.5 mg / mL MWCNTs dispersion and evenly drop it onto Cu x The coating area on the S / CF electrode surface is 0.8 cm². 2 Dry at 50℃ for 1 hour;

[0088] (5) Repeat steps (3)-(4) once;

[0089] (6) Take 20 μL of 0.0478 mg / mL gold nanoparticle dispersion and coat it evenly onto the electrode obtained in step (5), with a coating area of ​​0.8 cm². 2 The final electrode was obtained by drying at 50°C for 3 hours and labeled as Au / MWCNTs / Cu. x S / CF.

[0090] Example 12: Preparation of an enzyme-free glucose sensor electrode

[0091] (1) Add 50 mL of 0.01% HAuCl4 to a three-necked flask, stir continuously and heat to boiling, then add 1.7 mL of 1% sodium citrate solution and 0.5 mL of 1% PVP solution to the three-necked flask in sequence, continue heating for 30 min, then stop and cool to room temperature to prepare a nano-gold dispersion with a concentration of 0.0478 mg / mL;

[0092] (2) Weigh 0.0015 g of MWCNTs (length 10-30 μm, outer diameter 20-30 nm) powder, and make up to 1 mL with a mixture of Nafion solution (5% w / w) and ethanol (the volume ratio of Nafion solution to ethanol is 1:9). Disperse the mixture by sonication for 10 min to obtain a MWCNTs dispersion with a concentration of 1.5 mg / mL.

[0093] (3) Immerse the copper foam in 0.1M CoSO4 solution (0.281g of CoSO4·7H2O, diluted to 10mL with a 1:4 volume ratio of methanol and water) for 10s, rinse with deionized water to remove excess ions, and then immerse in 0.2M Na2S solution (0.48g of Na2S·9H2O, diluted to 10mL with a 1:4 volume ratio of methanol and water) for 10s, rinse with deionized water to remove excess ions, thus obtaining CoS-Cu. x S / CF electrode;

[0094] (4) Take 60 μL of 1.5 mg / mL MWCNTs dispersion and evenly drop it onto CoS-Cu. x The coating area on the S / CF electrode surface is 0.8 cm². 2 Dry at 50℃ for 1 hour;

[0095] (5) Repeat steps (3)-(4) once;

[0096] (6) Take 20 μL of 0.0478 mg / mL gold nanoparticle dispersion and coat it evenly onto the electrode obtained in step (5), with a coating area of ​​0.8 cm². 2 The final electrode was obtained by drying at 50°C for 3 hours and labeled as (Au / MWCNTs / CoS-Cu). x S / CF).

[0097] Example 13: Preparation of an enzyme-free glucose sensor electrode

[0098] (1) Add 0.8cm of copper foam. 2 Immerse in 0.1M CoSO4-NiSO4 solution (0.21g CoSO4·7H2O and 0.065g NiSO4·6H2O, diluted to 10mL with a 1:4 volume ratio of methanol and water) for 10s, rinse with deionized water to remove excess ions, then immerse in 0.2M Na2S solution (0.48g Na2S·9H2O, diluted to 10mL with a 1:4 volume ratio of methanol and water) for 10s, and rinse with deionized water to remove excess ions.

[0099] (2) Repeat step (1) once to obtain CoS-NiS-Cu. xS / CF electrode.

[0100] Performance testing

[0101] 1. Material Characterization

[0102] The (Au / MWCNTs / CoS-NiS-Cu) prepared in Example 1 x Taking the S / CF)1 electrode as an example, performance tests were conducted as follows:

[0103] (1) The prepared electrode (Au / MWCNTs / CoS-NiS-Cu) was observed using scanning electron microscopy (SEM). x The morphology of S / CF)1.

[0104] Figure 1 Electrode (Au / MWCNTs / CoS-NiS-Cu) x SEM image of S / CF1. The image shows slender, curved carbon nanotubes encased in nanoflowers formed by aggregates of 20-30 nm nanoparticles; these nanoflowers are trimetallic sulfides. Elemental analysis of the material was performed using energy dispersive spectroscopy.

[0105] Figure 2 Electrode (Au / MWCNTs / CoS-NiS-Cu) x EDS plot of S / CF1. The test results show that Co, Cu, Ni, C, Au, and S elements are uniformly distributed on the electrode surface.

[0106] (2) X-ray electron spectroscopy was used to test (Au / MWCNTs / CoS-NiS-Cu) x Composition and valence state of S / CF1 material.

[0107] To obtain information on the composition and valence state of trimetallic sulfides, X-ray electron spectroscopy was used to analyze (Au / MWCNTs / CoS-NiS-Cu). x Composition and valence state of S / CF1 material.

[0108] Figure 3 The X-ray photoelectron spectrum of electrode (Au / MWCNTs / CoS-NiS-CuxS / CF)1 is shown below. Figure 3 (a) is the XPS full spectrum, indicating that the material contains elements Co, Cu, Ni, C, Au, and S. Figure 3 (b)-3(e) are XPS spectra of Ni2p, Co2p, Cu2p, and S2p, respectively, confirming the presence of Ni in the material. 2+ Co 2+ Cu is present at the same time + and Cu 2+ S also exists2- This indicates that CoS-NiS-Cu was successfully synthesized. x S(1<x<2) trimetallic sulfides.

[0109] (3) The prepared electrode (Au / MWCNTs / CoS-NiS-Cu) was observed using a transmission microscope (TEM). x Morphology of S / CF)1. To obtain the morphology of gold nanoparticles, TEM was performed on the gold nanoparticles separately. Figure 4 Transmission electron microscopy (TEM) images of the sensor electrode material (a) and the gold nanomaterial (b).

[0110] Among them, from Figure 4 (a) The electrode (Au / MWCNTs / CoS-NiS-Cu) is visible. x The S / CF)1 material contains a large number of carbon nanotubes, and there are many nanoparticles of about 20-30 nm between and on the carbon nanotubes. These nanoparticles are in an aggregated state and are trimetallic sulfides.

[0111] from Figure 4 (b) It can be seen that the gold nanoparticles are uniform in size, ranging from 1 to 5 nm.

[0112] 2. Contains (Au / MWCNTs / CoS-NiS-Cu) x Electrochemical performance testing of glucose sensor with S / CF1 electrode

[0113] The (Au / MWCNTs / CoS-NiS-Cu) prepared in Example 1 x A glucose three-electrode system was constructed using an S / CF)1 electrode as the working electrode, a platinum sheet as the counter electrode, and an Ag / AgCl electrode as the reference electrode, with 0.1M NaOH solution as the electrolyte for testing.

[0114] (1) Electrocatalytic activity on glucose

[0115] At a potential of -0.2 to 0.8 V, 0.5 mM glucose was added to the electrolyte, and the test electrode (Au / MWCNTs / CoS-NiS-Cu) was tested. x Cyclic voltammetry curves of S / CF1 in the absence and presence of glucose.

[0116] Figure 5 The results show that a significant catalytic current was observed when glucose was added, indicating that the electrode has good catalytic activity for glucose.

[0117] Cyclic voltammetry scans were performed by gradually increasing the scan rate within a potential range of -0.2 to 0.8 V to observe the current response of the electrode to glucose.

[0118] Figure 6(a) shows the CV plots of the electrode material in an electrolyte containing 0.5 mM glucose at different scan rates (20-120 mV / s).

[0119] like Figure 6 As shown in (b), with the increase of the scan rate, the peak current density of both the cathode and anode shows a good linear relationship with the square root of the scan rate, with linear correlation coefficients R0 and R1 respectively. pa 2 =0.993, R pc 2 =0.996, indicating that the electrochemical reaction process of this electrode is controlled by surface adsorption.

[0120] (2) Linear range, detection limit and sensitivity

[0121] Under constant potential scanning at 0.6V, glucose solutions of varying concentrations from low to high were continuously added to the electrolyte at 50s intervals to obtain the time-current curves of the electrode response to different glucose concentrations.

[0122] The results are as follows Figure 7 As shown in (a), the electrode responds well to different concentrations of glucose.

[0123] according to Figure 7 (b) It can be seen that the current density increases linearly with the glucose concentration from 0.01 mM to 9 mM, and the linear equation is: y = 0.93625x + 0.08372(R) 2 =0.99316), sensitivity is 936.25 μA·mM -1 ·cm -2 The detection limit is 7.5 μM.

[0124] (3) Anti-interference performance

[0125] At a constant potential of 0.6V, 0.1mM glucose, 0.01mM cysteine, 0.01mM ascorbic acid, 0.01mM dopamine hydrochloride, 0.01mM uric acid and 0.1mM glucose were added sequentially to the electrolyte to test the anti-interference performance of the electrode.

[0126] like Figure 8 The results show that the current response of these interfering substances is negligible compared to the current response of 0.1 mM glucose, thus the electrode material exhibits excellent selectivity.

[0127] (4) Stability and reproducibility

[0128] Under a voltage of 0.6V and continuous uniform stirring, 0.5mM glucose was added to the test system, and the current response of the electrode at different times was measured.

[0129] like Figure 9 As shown, the current density can still reach 94% of the first current density, indicating that the sensor has good stability.

[0130] Five identical sensors were prepared, and 0.5 mM glucose was added to each sensor in the test system. Figure 10 The relative standard deviation (RSD) of the peak current response value is less than 5%, indicating that the constructed enzyme-free glucose sensor has good reproducibility.

[0131] 3. Collaboration ability

[0132] Cyclic voltammetry curves of bare copper foam (CF) and different electrodes prepared in Examples 1, 6, and 9 were tested in the presence of 0.5 mM glucose at potentials ranging from -0.2 to 0.8 V, with 0.5 mM glucose added to the electrolyte.

[0133] like Figure 11 As shown in the figure, the comparison reveals that CoS-NiS-Cu x S / CF, MWCNTs / CoS-NiS-Cu x S / CF and (Au / MWCNTs / CoS-NiS-Cu) x The overall peak current response of the S / CF1 electrode gradually increases, indicating that the CoS-NiS-Cu in the electrode... x S, MWCNTs, and gold nanoparticles exhibit significant synergistic effects.

[0134] Under a constant potential scan of 0.6V, glucose solutions of varying concentrations from low to high were continuously added dropwise to the electrolyte at 50-second intervals. The linear range, sensitivity, and detection limit of the electrodes prepared in Examples 1-13 for glucose detection were tested. The results are shown in Table 1.

[0135] Comparing Examples 1, 2, and 3, it can be seen that when the amounts of MWCNTs dispersion and gold nanoparticle dispersion are 0.1125 mg / cm³, respectively... 2 0.956 μg / cm 2 At that time, the (Au / MWCNTs / CoS-NiS-Cu) obtained x The S / CF)1 electrode exhibits good linear range and sensitivity.

[0136] Comparing Examples 1, 10, and 13, it can be seen that (Au / MWCNTs / CoS-NiS-Cu) x S / CF)1 electrode ratio MWCNTs / CoS-NiS-Cu x S / CF and CoS-NiS-Cu x The S / CF electrode exhibits a significantly wider linear range and higher sensitivity, further demonstrating the superior performance of the CoS-NiS-Cu electrode. xThe three materials, S, MWCNTs, and gold nanoparticles, exhibit a significant synergistic effect.

[0137] Comparing Examples 1, 11, and 12, it can be seen that (Au / MWCNTs / CoS-NiS-Cu) x S / CF)1 electrode ratio Au / MWCNTs / CoS-Cu x S / CF and Au / MWCNTs / Cu x The S / CF electrode exhibits a wider linear range and higher sensitivity, indicating that trimetallic sulfides are more effective at catalyzing glucose than dimetallic and monometallic sulfides.

[0138] Comparing Examples 1, 4, and 5, it can be seen that, compared to 0 and 2 times, when steps (3)-(4) are repeated 1 time, the obtained electrode (Au / MWCNTs / CoS-NiS-Cu) x S / CF)1 has a wider linear range and higher sensitivity.

[0139] Comparing Examples 1, 6, and 7, it can be seen that when the concentration of the CoSO4-NiSO4 solution is 0.05-0.15M and the concentration of the Na2S solution is 0.15-0.25M, the linear range and sensitivity of the prepared sensors are not significantly different. However, when the concentration of the CoSO4-NiSO4 solution is 0.1M and the concentration of the Na2S solution is 0.2M, the (Au / MWCNTs / CoS-NiS-Cu) sensor is significantly different. x The S / CF)1 electrode exhibits good linear range and sensitivity.

[0140] Comparing Examples 1, 8, and 9, it can be seen that when the Co / Ni molar ratio is 2-4:1, the linear range and sensitivity of the fabricated sensors are not significantly different. However, when the Co / Ni molar ratio is 3:1, the resulting (Au / MWCNTs / CoS-NiS-Cu) sensors exhibit significant differences. x The S / CF)1 electrode exhibits good linear range and sensitivity.

[0141] Table 1. Linear range, sensitivity, and detection limit for glucose detection of the electrodes prepared in Examples 1-13.

[0142]

[0143] In summary, this invention modifies the surface of copper foam with a cobalt-nickel-copper trimetallic sulfide (CoS-NiS-CuxS), MWCNT dispersion, and nano-gold dispersion to obtain an enzyme-free glucose sensor electrode with a wide linear range, high sensitivity, good stability, and high selectivity. Furthermore, its preparation method is simple, the conditions are mild, and the entire process does not involve medium- or high-temperature heat treatment, making it energy-saving, environmentally friendly, and low-cost, suitable for large-scale production.

[0144] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as a limitation of the present invention.

[0145] The specific embodiments of the present invention have been described in detail above, but they are merely examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, all equivalent transformations and modifications made without departing from the spirit and scope of the present invention should be covered within the scope of the present invention.

Claims

1. A three-metal sulfide-based, enzyme-free glucose sensor electrode, characterized in that, The electrode comprises a foam copper substrate and cobalt-nickel-copper ternary sulfide (CoS-NiS-Cu x S), multi-walled carbon nanotubes and nano-gold material loaded on the surface of the foam copper substrate. The multi-walled carbon nanotubes are modified on the electrode in two layers. The first layer is modified on a cobalt-nickel-copper trimetallic sulfide, and the second layer is modified on a multi-walled carbon nanotube layer loaded with CoS-NiS nanoparticles to form a nanoflower structure. The gold nanomaterial was finally loaded onto the surface of the modified electrode.

2. The enzyme-free glucose sensor electrode of claim 1, wherein, The cobalt-nickel-copper trimetallic sulfide (CoS-NiS-Cu) x Cu in S) x S is obtained using copper foam as the copper source and only adheres to the surface of the copper foam, while cobalt-nickel-copper trimetallic sulfides (CoS-NiS-Cu) x CoS-NiS in S) not only adheres to the surface of copper foam, but also to multi-walled carbon nanotubes, so that the multi-walled carbon nanotubes are encapsulated in nanoflowers formed by the aggregation of CoS-NiS nanoparticles.

3. The enzyme-free glucose sensor electrode of claim 1, wherein, The surface of the foamed copper is coated with the cobalt-nickel-copper trimetallic sulfide (CoS-NiS-Cu). x S), the multi-walled carbon nanotubes are modified on the electrode in two layers. The first layer of multi-walled carbon nanotubes is modified on the pre-loaded cobalt-nickel-copper trimetallic sulfide, which serves as a support to support the CoS-NiS nanoparticles grown by the second SILAR method. The second layer of multi-walled carbon nanotubes is modified on the multi-walled carbon nanotube layer loaded with CoS-NiS nanoparticles. Finally, the gold nanomaterial is loaded onto the modified electrode surface.

4. A method for preparing a glucose sensor electrode based on a trimetallic sulfide without enzyme, characterized by, Includes the following steps: (1) Add sodium citrate solution and polyvinylpyrrolidone solution to HAuCl4 solution, heat and stir to obtain a gold nanoparticle dispersion; (2) Disperse MWCNTs (multi-walled carbon nanotubes) in a mixed solution of perfluorinated resin (Nafion) and ethanol, and mix them evenly by ultrasonication to obtain MWCNTs dispersion. (3) Immerse copper foam (CF) in a methanol aqueous solution of cobalt sulfate and nickel sulfate for a certain period of time to remove excess ions, then immerse it in a methanol aqueous solution of sodium sulfide for a certain period of time to remove excess ions. Cobalt-nickel-copper trimetallic sulfide (CoS-NiS-Cu) is generated on the copper foam through continuous ion layer reaction and adsorption (SILAR). x S), to obtain CoS-NiS-Cu x S / CF electrode; (4) CoS-NiS-Cu obtained in step (3) was added to 10 mL of 0.1 M NaOH solution and stirred for 2 hours at 60°C. x MWCNTs dispersion solution obtained in step (2) was dropped on the S / CF electrode and dried; (5) Repeat steps (3) to (4) once to dry; (6) The nano-gold dispersion from step (1) is dropped onto the electrode obtained in step (5), and after drying, a gold / multi-walled carbon nanotube / cobalt-nickel-copper trimetallic sulfide / foamed copper electrode (Au / MWCNTs / CoS-NiS-Cu) is obtained. x S / CF); The SILAR reaction solution was prepared using a mixed solvent of methanol and water in a volume ratio of 1:

4.

5. The method of claim 4, wherein the step of forming the glucose sensor electrode is performed without using an enzyme. In step (1), the concentration of the gold nanoparticle dispersion is 0.0239-0.0717 mg / mL and the particle size is 1-5 nm.

6. The method of claim 4, wherein the step of forming the glucose sensor electrode is performed without using an enzyme. In step (2), the length of the MWCNTs (multi-walled carbon nanotubes) is 10-30 μm and the outer diameter is 20-30 nm; The concentration of the Nafion solution was 5% (w / w), the volume ratio of Nafion solution to ethanol was 1:9, and the concentration of the obtained MWCNTs dispersion was 1-2 mg / mL.

7. The method of claim 4, wherein the step of forming the glucose sensor electrode is performed without using an enzyme. In step (3), the volume ratio of methanol to water in the methanol-water solution of cobalt sulfate and nickel sulfate is 0.5-1.5:4, and the immersion time is 6-14 s; The concentration of the CoSO4-NiSO4 solution is 0.05-0.15 M, the cobalt-nickel molar ratio is 2-4:1, and the concentration of the Na2S solution is 0.15-0.25 M.

8. The method of claim 4, wherein the electrode is a glucose sensor electrode. In step (4), the coating amount of the MWCNTs dispersion is 0.075-0.15 mg / cm³. 2 The drying temperature is 50-60℃, and the drying time is 0.5-1.5 h.

9. The method of claim 4, wherein the electrode is a glucose sensor electrode. In step (6), the coating amount of the gold nanoparticle dispersion is 1.195-1.7925 μg / cm³. 2 The drying temperature is 50-60℃, and the drying time is 2-4 hours.

10. The use of the enzyme-free glucose sensor electrode as described in any one of claims 1 to 3 and / or the enzyme-free glucose sensor electrode prepared by the method as described in any one of claims 4 to 9 in the fabrication of a glucose sensor.

Images