Preparation method and application of AgGaS2 / MWCNTs / SPE electrode

Abstract

This invention discloses a method for preparing an AgGaS2 / MWCNTs / SPE electrode and its application, relating to the field of electrochemical detection technology. The key technical points are: this method uses a one-step hydrothermal method to synthesize bimetallic sulfide AgGaS2 nanoplatelets, which are then mixed with acidified multi-walled carbon nanotubes via simple ultrasonication to obtain a bimetallic sulfide composite carbon material (AgGaS2 / MWCNTs). The synthesized material has a large specific surface area and abundant active sites. The above material is prepared into a suspension using ultrapure water, and a novel sensitive electrode, AgGaS2 / MWCNTs / SPE, for detecting shikonin is successfully constructed using a conventional drop-coating method. This electrode exhibits high selectivity, sensitivity, and stability.

Description

Technical Field

[0001] This invention relates to the field of electrochemical detection technology, and more specifically, to a method for preparing an AgGaS2 / MWCNTs / SPE electrode and its application. Background Technology

[0002] For electrochemical sensors, suitable electrode materials play a crucial role, significantly impacting detection performance. Chalcogenide bimetallic compounds possess excellent physicochemical properties such as low cost, high catalytic activity, and good long-term stability; however, their relatively poor conductivity limits their development and application. Carbon materials, on the other hand, offer advantages such as strong conductivity, strong chemical stability, and a large specific surface area. Combining carbon with bimetallic sulfides creates new electrochemical active sites, which can improve the electrochemical properties of the material, simultaneously enhancing the electronic conductivity and catalytic performance of the composite material.

[0003] Shikonin (SHI) is a naphthoquinone compound extracted from natural plants. Due to its diverse pharmacological activities, including antitumor, anti-inflammatory, antibacterial, antiviral, and antithrombotic effects, it has attracted widespread attention from researchers and has long been used to treat burns, hemorrhoids, urticaria, and other allergic diseases. Furthermore, shikonin possesses strong and stable coloring properties, exhibiting different colors at different pH values. In the chemical industry, it can also be used as a natural colorant in pharmaceuticals, cosmetics, and food.

[0004] Currently, various techniques have been reported for determining SHI in various samples, including titration, chemiluminescence, fluorescent probe methods, thin-layer chromatography, high-performance liquid chromatography, spectrophotometry, and electrochemical analysis. Compared with other methods, electrochemical analysis offers advantages such as low cost, high sensitivity, low detection limit, fast response, wide linear range, good selectivity and stability, and simple sample pretreatment, making it a popular detection method. Furthermore, SHI is an electroactive compound, making it highly suitable for measurement using electrochemical strategies. Therefore, there is an urgent need to develop an electrode that can perform simple, rapid, economical, and sensitive qualitative and quantitative detection of SHI. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing an AgGaS2 / MWCNTs / SPE electrode and its application. This electrode material is simple to prepare, has a relatively sensitive electrochemical response, and when used to detect the content of shikonin in a solution, the detection results are reliable, accurate, and have strong anti-interference ability.

[0006] The above-mentioned technical objective of this invention is achieved through the following technical solution: a method for preparing an AgGaS2 / MWCNTs / SPE electrode, comprising the following four steps:

[0007] Preparation of S1.AgGaS2 nanoplates;

[0008] Acidification of S2.MWCNTs;

[0009] Preparation of S3.AgGaS2 / MWCNTs composite suspension;

[0010] Preparation of S4.AgGaS2 / MWCNTs / SPE electrode.

[0011] The present invention is further configured as follows: the specific operation for preparing the AgGaS2 nanoplates in S1 is as follows: Ga(NO3)3·H2O and AgNO3 are weighed in the first beaker and dissolved in ultrapure water, and ultrasonically homogenized to obtain solution A; mercaptoacetic acid is measured in the second beaker and dissolved in ultrapure water to obtain solution B; thioacetamide is weighed in the third beaker and dissolved in ultrapure water, and ultrasonically homogenized to obtain solution C; solution B is added dropwise to solution A, and the mixed solution quickly turns bright yellow. After stirring, solution C is slowly added dropwise, and ultrasonically stirred to obtain a uniform brown solution. Then, the obtained brown solution is transferred to a stainless steel autoclave lined with polytetrafluoroethylene, heated in an oven for reaction, naturally cooled to room temperature, centrifuged, washed with ethanol, and the solid is collected and dried overnight.

[0012] The present invention is further configured as follows: the specific operation of acidification of MWCNTs in S2 is as follows: under continuous stirring, concentrated sulfuric acid is added to concentrated nitric acid to prepare a mixed acid with a volume ratio of concentrated sulfuric acid to concentrated nitric acid of 3:1. Then, MWCNTs are added, and the mixture is ultrasonically treated in an ice bath to obtain a dispersion. The dispersion is refluxed and then cooled to room temperature. The acidified MWCNTs are added to ultrapure water for dilution and filtered using a polytetrafluoroethylene microfiltration membrane. After repeated washing until neutral, the solid is collected and dried overnight in a vacuum environment.

[0013] The present invention is further configured as follows: the specific operation for preparing the AgGaS2 / MWCNTs composite suspension in S3 is as follows: weigh the AgGaS2 prepared in S1 and the MWCNTs prepared in S2 and disperse them in ultrapure water to form a uniform suspension. Mix the two dispersions in a 1:1 volume ratio with ultrasound for 2-3 days to obtain the composite suspension.

[0014] The present invention is further configured as follows: the specific operation for preparing the AgGaS2 / MWCNTs / SPE electrode in S4 is as follows: peel off the film on the front side of the SPE electrode, use a pipette to draw up the AgGaS2 / MWCNTs suspension prepared in S3, drop it onto the prepared SPE electrode surface, and place it at room temperature to dry until the material forms a uniform film on the electrode surface, thereby obtaining the AgGaS2 / MWCNTs / SPE electrode.

[0015] Application of an AgGaS2 / MWCNTs / SPE electrode: This electrode can be used to detect the content of shikonin in solution.

[0016] In summary, the present invention has the following beneficial effects: the electrode material is simple to prepare, has a relatively sensitive electrochemical response, and the detection results of the shikonin content in the solution using the electrode are reliable, accurate, and have strong anti-interference ability. Attached Figure Description

[0017] Figure 1 A represents the electrochemical impedance of different modified electrodes in the embodiments of the present invention; Figure 1 B. DPV curves of different modified electrodes in 3.5 μM SHI in the embodiments of the present invention;

[0018] Figure 2 A is the DPV response diagram of AgGaS2 / MWCNTs / SPE of the present invention at different SHI concentrations (0.0005μM, 0.001μM, 0.005μM, 0.01μM, 0.03μM, 0.05μM, 0.1μM, 0.3μM, 0.5μM, 1μM, 2μM, 3μM, 5μM, 7μM, 10μM, 13μM, 19μM, 25μM); Figure 2 Relationship between BAgGaS2 / MWCNTs / SPE detection signal and the logarithm of SHI concentration;

[0019] Figure 3 A shows the DPV response results measured by six modified electrodes in PBS (pH=5.5) buffer containing 3.5 μM HI. Figure 3 B represents the DPV response results obtained by measuring the same modified electrode 12 times consecutively in PBS (pH=5.5) buffer containing 3.5 μM HI. Figure 3 C represents the DPV response results in PBS (pH=5.5) buffer containing 3.5 μM HI, with the presence of different interfering substances. Detailed Implementation

[0020] The following is in conjunction with the appendix Figure 1-3 The present invention will be described in further detail below.

[0021] Example: A method for preparing an AgGaS2 / MWCNTs / SPE electrode, comprising the following four steps:

[0022] Preparation of S1.AgGaS2 nanoplates;

[0023] Acidification of S2.MWCNTs;

[0024] Preparation of S3.AgGaS2 / MWCNTs composite suspension;

[0025] Preparation of S4.AgGaS2 / MWCNTs / SPE electrode.

[0026] The specific steps for preparing AgGaS2 nanoplates in S1 are as follows: In the first beaker, 0.1369 g of Ga(NO3)3·H2O and 0.085 g of AgNO3 were weighed and dissolved in 10 mL of ultrapure water. The solution was ultrasonically homogenized to obtain solution A. In the second beaker, 430 μL of mercaptoacetic acid was measured and dissolved in 11.57 mL of ultrapure water to obtain solution B. In the third beaker, 0.1503 g of thioacetamide was weighed and dissolved in 10 mL of ultrapure water. The solution was ultrasonically homogenized to obtain solution C. Solution B was added dropwise to solution A. The mixed solution quickly turned bright yellow. After stirring for 15 min, solution C was slowly added dropwise. The mixture was ultrasonically stirred for 1 h to obtain a uniform brown solution. The obtained solution was then transferred to a stainless steel autoclave lined with polytetrafluoroethylene. The autoclave was heated at 180 °C for 12 h in an oven. After naturally cooling to room temperature, the mixture was centrifuged at 8000 rpm for 5 min. The solid was washed with ethanol and collected. The solid was dried overnight at 60 °C.

[0027] The specific operation for acidifying MWCNTs in S2 is as follows: Under continuous stirring, 15 mL of concentrated sulfuric acid was added to 5 mL of concentrated nitric acid to obtain a mixed acid with a volume ratio of concentrated sulfuric acid to concentrated nitric acid of 3:1. Then, 0.1 g of MWCNTs was added, and the mixture was sonicated in an ice bath for 20 min to obtain a dispersion. The dispersion was refluxed at 70 °C for 1.5 h and cooled to room temperature. The acidified MWCNTs were added to 200 mL of ultrapure water for dilution and filtered using a polytetrafluoroethylene microfiltration membrane with a pore size of 220 nm. After repeated washing until neutral, the solid was collected and dried overnight at 60 °C in a vacuum environment.

[0028] The specific steps for preparing the AgGaS2 / MWCNTs composite suspension in S3 are as follows: Weigh 2 mg of AgGaS2 prepared in S1 and 2 mg of MWCNTs prepared in S2 and disperse them separately in 1 ml of ultrapure water to form a uniform suspension. Mix the two dispersions ultrasonically at a 1:1 volume ratio for 2-3 days to obtain a concentration of 2 mg / mL. -1 Composite suspension.

[0029] The specific steps for preparing the AgGaS2 / MWCNTs / SPE electrode in S4 are as follows: peel off the film on the front of the SPE electrode, use a pipette to draw up 15 μL of the AgGaS2 / MWCNTs suspension prepared in L3, drop it onto the prepared SPE electrode surface, and place it at room temperature to dry until the material forms a uniform film on the electrode surface, thus obtaining the AgGaS2 / MWCNTs / SPE electrode.

[0030] The prepared electrodes can be used to detect the content of shikonin in solution. The detection process was performed on a CHI660 electrochemical workstation using screen-printed electrodes (SPE), with a carbon electrode as the auxiliary electrode, an Ag / AgCl electrode as the reference electrode, and the modified electrode as the working electrode. The electrolyte solution used in the electrochemical detection section was 0.1M phosphate buffered solution (PBS), and the detection was always conducted under a nitrogen atmosphere. The potential range of differential pulse voltammetry (DPV) was set to 0.2V–0.7V. Electrochemical impedance spectroscopy (EIS) was performed in a 5.0mM potassium ferricyanide / potassium ferrocyanide mixed solution containing 0.1M potassium chloride.

[0031] As can be seen from the above preparation method, an AgGaS2 / MWCNTs / SPE electrode preparation step yields an AgGaS2 and MWCNTs suspension. To compare the electrode prepared in this invention with these two, the AgGaS2 and MWCNTs suspensions were respectively drop-coated onto the surface of the SPE electrode to obtain the AgGaS2 / SPE electrode and the MWCNTs / SPE electrode, respectively. These three electrodes and the bare SPE electrode were then placed in an AC impedance electrolyte for electrochemical AC impedance testing. The test results are as follows: Figure 1 As shown in Figure A, in EIS, the semicircle diameter of the curve in the Nyquist plot is proportional to the impedance (Rp) of the working electrode surface material. It is evident that the bare SPE electrode has the highest impedance. The impedance of AgGaS2 / SPE is slightly lower than that of the bare SPE electrode, but its semicircle diameter is still relatively large. The curve radius corresponding to AgGaS2 / MWCNTs / SPE is smaller, while the curve corresponding to MWCNTs / SPE is almost a straight line. This indicates that among the three materials, AgGaS2 / MWCNTs has an electron transfer capability only slightly lower than MWCNTs, exhibiting excellent electron transport capability.

[0032] The three modified electrodes described above were tested using differential pulse voltammetry (DPV), and the electrochemical response results are as follows: Figure 1 As shown in Figure B, it can be clearly seen that the AgGaS2 / MWCNTs / SPE exhibits the strongest electrochemical response signal for the analyte shikonin, which is approximately 2.6 times stronger than that of MWCNTs / SPE.

[0033] After finding the optimal experimental procedure through numerous experiments, in order to study the linear equation, linear range, and detection limit of the AgGaS2 / MWCNTs / SPE electrode for detecting SHI, the AgGaS2 / MWCNTs / SPE electrode was placed in a 0.1M PBS buffer solution containing shikonin at pH 5.5. The current response results are as follows: Figure 2 As shown in A, Figure 2Figure A shows a superimposed graph of the electrochemical response results of shikonin at different concentration gradients (0.0005 μM, 0.001 μM, 0.005 μM, 0.01 μM, 0.03 μM, 0.05 μM, 0.1 μM, 0.3 μM, 0.5 μM, 1 μM, 2 μM, 3 μM, 5 μM, 7 μM, 10 μM, 13 μM, 19 μM, 25 μM). The results show that in 0.1 M PBS (pH = 5.5) solution, the oxidation peak current gradually increases with increasing SHI concentration. Figure 2 As shown in Figure B, within the range of 0.5 nM to 25 μM, the peak current value exhibits two segments of good linear correlation with the logarithm of the detectant concentration. The equations for the linear relationship are shown below:

[0034] Ip1(μA)=1.1643logC1(μM)+4.5108(R 2 =0.9963)

[0035] Ip2(μA)=56.5418logC2(μM)+30.8553(R 2 =0.9923)

[0036] Therefore, we have successfully built a novel electrochemical sensing platform for the detection of shikonin. The prepared electrode AgGaS2 / MWCNTs / SPE can be used to detect shikonin. This electrode material is simple to prepare and has a relatively sensitive electrochemical response.

[0037] To investigate the reproducibility of the AgGaS2 / MWCNTs / SPE electrode for detecting shikonin, DPV technology was used to measure the current response of six AgGaS2 / MWCNTs modified electrodes to 3.5 μM SHI in PBS (pH=5.5) buffer solution. The experimental results are as follows: Figure 3 As shown in Figure A, the current response of the six electrodes showed virtually no deviation, with a relative standard deviation (RSD) of 0.52%, indicating that the electrode has excellent repeatability and the test results are reliable.

[0038] To investigate the reproducibility of the AgGaS2 / MWCNTs / SPE electrode for detecting shikonin, the same DPV technique was used. The same modified electrode was used to perform 12 repeated measurements in PBS (pH=5.5) buffer containing 3.5 μM HI. The relative standard deviation (RSD) was 1.87%, indicating that the electrode's detection results have good reproducibility and high accuracy.

[0039] To investigate the anti-interference ability of the AgGaS2 / MWCNTs / SPE electrode for detecting shikonin, 100 times the concentration of K+ ions was added to a PBS (pH=5.5) buffer containing 3.5 μM HI. + Zn 2+ Al3+ Mg 2+ SO4 2- NO3 - Other interfering substances at 10 times concentration: glucose, ascorbic acid, uric acid, glycine, L-arginine, citric acid, vitamin K3, the DPV peak current value hardly decreased, with a relative standard deviation of 1.13%, indicating that the prepared AgGaS2 / MWCNTs / SPE electrode has good anti-interference ability.

[0040] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for preparing an AgGaS2 / MWCNTs / SPE electrode, characterized in that: It includes the following 4 steps: Preparation of S1.AgGaS2 nanoplates; Acidification of S2.MWCNTs; Preparation of S3.AgGaS2 / MWCNTs composite suspension; Preparation of S4.AgGaS2 / MWCNTs / SPE electrode.

2. The method for preparing an AgGaS2 / MWCNTs / SPE electrode according to claim 1, characterized in that: The specific preparation of AgGaS2 nanoplates in S1 is as follows: In the first beaker, Ga(NO3)3·H2O and AgNO3 are weighed and dissolved in ultrapure water, and ultrasonically homogenized to obtain solution A. In the second beaker, mercaptoacetic acid is measured and dissolved in ultrapure water to obtain solution B. In the third beaker, thioacetamide is weighed and dissolved in ultrapure water, and ultrasonically homogenized to obtain solution C. Solution B is added dropwise to solution A, and the mixed solution quickly turns bright yellow. After stirring, solution C is slowly added dropwise, and ultrasonically stirred to obtain a uniform brown solution. Then, the obtained brown solution is transferred to a stainless steel autoclave lined with polytetrafluoroethylene, heated in an oven, and allowed to cool naturally to room temperature. After centrifugation, the solid is washed with ethanol and collected, and dried overnight.

3. The method for preparing an AgGaS2 / MWCNTs / SPE electrode according to claim 1, characterized in that: The specific operation of acidification of MWCNTs in S2 is as follows: under continuous stirring, concentrated sulfuric acid is added to concentrated nitric acid to prepare a mixed acid with a volume ratio of concentrated sulfuric acid to concentrated nitric acid of 3:

1. Then, MWCNTs are added, and the mixture is ultrasonically treated in an ice bath to obtain a dispersion. The dispersion is refluxed and then cooled to room temperature. The acidified MWCNTs are added to ultrapure water for dilution and filtered using a polytetrafluoroethylene microfiltration membrane. After repeated washing until neutral, the solid is collected and dried overnight in a vacuum environment.

4. The method for preparing an AgGaS2 / MWCNTs / SPE electrode according to claim 1, characterized in that: The specific operation for preparing the AgGaS2 / MWCNTs composite suspension in S3 is as follows: weigh the AgGaS2 prepared in S1 and the MWCNTs prepared in S2 and disperse them in ultrapure water to form a uniform suspension. Mix the two dispersions in a 1:1 volume ratio with ultrasound for 2-3 days to obtain the composite suspension.

5. The method for preparing an AgGaS2 / MWCNTs / SPE electrode according to claim 1, characterized in that: The specific operation for preparing the AgGaS2 / MWCNTs / SPE electrode in S4 is as follows: peel off the film on the front of the SPE electrode, use a pipette to pick up the AgGaS2 / MWCNTs suspension prepared in S3, drop it onto the prepared SPE electrode surface, and place it at room temperature to dry until the material forms a uniform film on the electrode surface, thus obtaining the AgGaS2 / MWCNTs / SPE electrode.

6. An application of an AgGaS2 / MWCNTs / SPE electrode, characterized in that: The AgGaS2 / MWCNTs / SPE electrode can be used to detect the content of shikonin in solution.

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