Preparation of a bismuth film and two-dimensional graphdiyne sensor and application thereof in one-step detection of multi-component heavy metal ions

Abstract

The application designs a kind of electrochemical sensor preparation based on bismuth film (Bi) and two-dimensional graphdiyne (GDY) and its application in one-step detection of multiple heavy metal ions. A kind of electrochemical sensor (Bi / GDY / GCE) capable of one-step sensitive detection of Zn 2+ , Cd 2+ , Pb 2+ is prepared by drop coating method and electrodeposition method. Mainly includes the following steps: (1) preparation of sensor: the glassy carbon electrode (GCE) is polished on the chamois leather with Al2O3 polishing powder, and then the electrode is washed with ultrapure water. GDY solution is drop coated on the surface of GCE, and then bismuth film is electrodeposited after air drying at room temperature. (2) application of sensor: the constructed electrochemical sensor is used for one-step detection of three heavy metal ions Zn 2+ , Cd 2+ , Pb 2+ by adsorption dissolution voltammetry. The application has simple process, low manufacturing cost, high detection efficiency and remarkable determination effect.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical sensor preparation and heavy metal ion analysis, and relates to the preparation of a bismuth membrane and a two-dimensional GDY sensor and its application in one-step detection of multi-component heavy metal ions. Background Technology

[0002] Industries such as paint, battery production, pesticides, and papermaking discharge large amounts of wastewater and waste containing heavy metal ions, exacerbating their pollution problems. Excessive levels of heavy metals like zinc, cadmium, and lead in the environment and food are increasingly posing a deadly threat. These heavy metals are non-biodegradable and accumulate in human organs and tissues through the food chain and drinking water, eventually exceeding critical limits and causing serious diseases. Zinc plays a vital role in the human body, but excessive zinc can impair liver or kidney function, leading to loss of smell. Cadmium can bind to protein molecules containing hydroxyl, amino, and sulfhydryl groups in the body, inhibiting many enzyme systems and leading to various cancers, cardiovascular diseases, and osteoporosis. Lead ions in the environment can cause death in children and severely damage the brain and kidneys, manifesting as kidney disease and colic-like abdominal pain. Therefore, developing a sensitive, simple, inexpensive, and reliable analytical method for monitoring and early warning of heavy metal ion concentrations in the aquatic environment is crucial.

[0003] Currently reported detection methods mainly include atomic absorption spectrometry, spectrophotometry, fluorescence methods, and inductively coupled plasma atomic emission spectrometry. These analytical methods often require highly trained analysts, sophisticated instruments, long detection times, and cumbersome sample preparation, which limits their application in daily production and life. Adsorption-stripping voltammetry (ASV), as an electrochemical technique, has attracted widespread attention due to its advantages over traditional methods, including high efficiency, simple operation, fast response speed, low cost, and high sensitivity. Zn in the aquatic environment... 2+ Pb 2+ and Cd 2+ The content of heavy metal ions is usually in the trace level, and existing electrochemical sensors are not sensitive enough and cannot detect multi-component heavy metal ions efficiently. Therefore, there is an urgent need to prepare an electrochemical sensor for heavy metal ions with higher sensitivity, higher detection efficiency and faster response speed.

[0004] Graphdiyne (GDY) is a novel all-carbon nanostructure material following fullerenes, carbon nanotubes, and graphene. Compared to graphene, GDY possesses richer carbon chemical bonds and a larger conjugated system, leading to higher sensitivity and better chemical stability in electrochemical sensors. Bismuth, as a green metal, exhibits low toxicity and good electrochemical performance, and can form alloys with various heavy metals, enabling one-step detection of multi-component heavy metal ions. An electrochemical sensor constructed using bismuth films and two-dimensional graphdiyne as a substrate has been developed for the detection of Zn.2+ Cd 2+ Pb 2+ This step-by-step detection has significant application value in the field of environmental monitoring. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of this invention is to provide a high-sensitivity one-step detection method for Zn. 2+ Cd 2 + Pb 2+ An electrochemical sensor and its preparation method.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A type of Zn 2+ Cd 2+ Pb 2+ A method for preparing a one-step detection electrochemical sensor, comprising the following steps:

[0008] (1) Polish the glassy carbon electrode (GCE) on chamois for about 1 to 2 minutes with Al2O3 polishing powder, and then clean the electrode with ultrapure water; drop GDY suspension is applied to the surface of GCE, and after drying, the modified electrode GDY / GCE is obtained.

[0009] (2) Continue to immerse GDY / GCE in bismuth salt solution, electrodeposit bismuth film, and then dry with nitrogen to obtain modified electrode Bi / GDY / GCE.

[0010] Preferably, in step (1), the GDY / GCE preparation process is as follows: 5 μL of GDY suspension with a concentration of 5.0 mg / mL is dropped onto the treated GCE surface and dried with an infrared lamp to obtain the modified electrode GDY / GCE.

[0011] Preferably, the preparation process of the GDY suspension is as follows: add ultrapure water to GDY powder, and then disperse it by ultrasonication for 30 min using a cell disruptor to obtain a GDY suspension of 5.0 mg / mL.

[0012] Preferably, in step (2), the process of electrodepositing bismuth film is as follows: GDY / GCE is immersed in an aqueous solution of 0.1 mM Bi(NO3)3, with Ag / AgCl as the reference electrode and a platinum wire electrode as the counter electrode, using the chronoamperometry (it) method, the deposition potential is -1.1 V, and the deposition time is 120 s.

[0013] An application based on a bismuth membrane and a two-dimensional GDY sensor, wherein the Bi / GDY / GCE is used for one-step detection of the concentration of multi-component heavy metal ions in an aquatic environment.

[0014] A method for simultaneous detection of Zn in the aquatic environment 2+ Cd 2+ and Pb 2+ In the concentration method, step (2), based on the application of the Bi / GDY / GCE electrochemical sensor, the method is as follows: using a three-electrode system, with Bi / GDY / GCE as the working electrode, Ag / AgCl as the reference electrode, and platinum wire as the counter electrode, in Zn 2+ Cd 2+ Pb 2+ Determination of Zn in aqueous environment using adsorption-stripping voltammetry in mixed electrolyte solution. 2+ Cd 2+ and Pb 2+ The electrochemical dissolution signal.

[0015] Preferably, a series of Zn concentrations are first enriched at a constant potential under stirring conditions. 2+ Cd 2+ Pb 2+ A standard buffer solution (preferably enrichment potential of -1.3 V, enrichment time of 150 s, and buffer solution of HAc-NaAc at pH 6.0) is used, followed by dissolution (dissolution potential scan range of -1.3 V to 0.2 V). The anodic dissolution peak current is obtained, and the relationship between the magnitude of the anodic dissolution peak current and Zn is analyzed. 2+ Cd 2+ Pb 2+ Logarithmic curves were plotted for the concentrations of each ion in the standard buffer solution. These curves were then used to analyze the Zn concentration in the aquatic environment. 2+ Cd 2+ Pb 2+ Conduct testing.

[0016] The selective determination of the Bi / GDY / GCE electrochemical sensor in this invention is performed by adding a solution containing other interfering ions to a solution containing Zn. 2+ Cd 2+ Pb 2+ In HAc-NaAc, adsorption-stripping voltammetry was performed under the same conditions and using the same method described above to study the changes in the characteristic peak potentials and peak currents of the anodic dissolution of three heavy metal ions, and to examine the selectivity of the electrochemical sensor. The interfering ion was Ni. 2+ Co 2+ Fe 3+ Cu 2+ Fe 2+ Mg 2+ Ca 2+ Mn 2+ and Cl - .

[0017] The stability of the Bi / GDY / GCE electrochemical sensor in this invention was determined by storing the prepared Bi / GDY / GCE in a refrigerator at 4°C for 6 days. Adsorption-dissolution voltammetry was performed daily under the same conditions and using the same method described above. The Zn content was then investigated. 2+ Cd 2+ Pb 2+ The stability of the electrochemical sensor was investigated by examining the changes in the characteristic peak potential and peak current of anodic dissolution.

[0018] In anodic stripping voltammetry, the stripping peak potentials of different metal ions are different, and the stripping peak current is proportional to the ion concentration, providing an effective and rapid platform for real-time detection of target analytes.

[0019] The electrochemical sensor prepared in this invention uses Bi / GDY as the modified material, which possesses good conductivity and excellent ability to enrich heavy metal cations. This enhances the enrichment of heavy metal cations by the working electrode under the measured potential conditions, making heavy metal ions easier to deposit, preventing hydrogen evolution at the working electrode, and enabling one-step detection of multiple heavy metal ions. Simultaneously, it improves the one-step detection throughput, lowers the detection limit, and broadens the linear range. Specifically, the modified electrode material Bi forms an "alloy" with heavy metal ions, thereby enhancing the enrichment capacity. GDY has a large surface area and electron transport capacity, which is beneficial for bismuth film deposition and signal transmission. The synergistic effect of Bi and GDY enhances their enrichment performance for heavy metal ions. Bi is uniformly dispersed on the highly conductive GDY, resulting in a large specific surface area and good electron transport rate in the composite material, which helps to achieve one-step, highly sensitive detection of multiple heavy metal ions.

[0020] This electrochemical sensor can detect heavy metal Zn. 2+ Cd 2+ Pb 2+ Highly sensitive one-step detection for Zn 2+ Cd 2+ Pb 2 + The detection limits were 1.46 pM, 1.15 pM, and 1.71 pM, respectively, and the linear range was 100 pM - 100 μM. Attached Figure Description

[0021] Figure 1 Cyclic voltammetry curves of Bi / GDY / GCE prepared for test example 1 at different scan rates in a mixed electrolyte of 1 mM K3[Fe(CN)6] and 0.5 M KCl;

[0022] Figure 2 The oxidation peak current and υ of Bi / GDY / GCE prepared for Test Example 1 at different scan rates are shown. 1 / 2A linear relationship;

[0023] Figure 3 (a) GCE, (b) GDY / GCE, (c) Bi / GCE, and (d) Bi / GDY / GCE were prepared for test example 1 in 100 μM Zn 2+ Cd 2+ Pb 2+ Adsorption-dissolution voltammetry in a HAc-NaAc mixed electrolyte at pH 6.0;

[0024] Figure 4 To test different volumes of Bi / GDY / GCE at 100 μM Zn in Example 1 with 5.0 mg / mL GDY. 2+ Cd 2+ Pb 2+ Adsorption-dissolution voltammetry in HAc-NaAc (pH 6.0) mixed electrolyte;

[0025] Figure 5 Optimization diagram for different types of buffer solutions in Test Example 1;

[0026] Figure 6 Optimization plot for different pH values ​​in Test Example 1;

[0027] Figure 7 Optimized plots of different enrichment potentials for test example 1;

[0028] Figure 8 Optimization plot for different enrichment times in Test Example 1;

[0029] Figure 9 Bi / GDY / GCE prepared for test example 2 with different concentrations of Zn 2+ Cd 2+ Pb 2+ Adsorption-dissolution voltammetry of HAc-NaAc (pH 6.0) mixed electrolyte;

[0030] Figure 10 Bi / GDY / GCE prepared with Zn at different concentrations 2+ Cd 2+ Pb 2+ The dissolution peak current in the electrolyte solution and log C A linear relationship;

[0031] Figure 11 Bi / GDY / GCE prepared for test example 2 were tested in Zn2 ​​without interfering ions (curve a) and with 100 μM interfering ions (curve b). 2+ Cd 2+ Pb 2+Adsorption and dissolution curves of HAc-NaAc (pH 6.0) mixed electrolyte, with Ni as the interfering ion. 2+ Co 2+ Fe 3+ Cu 2+ Fe 2+ Mg 2+ Ca 2+ Mn 2+ or Cl - ;

[0032] Figure 12 The Bi / GDY / GCE prepared for Test Example 2 was stored in a refrigerator at 4°C and subjected to 100 μM Zn for 6 consecutive days. 2+ Cd 2+ Pb 2+ The dissolution peak current in the HAc-NaAc (pH 6.0) mixed electrolyte. Detailed Implementation

[0033] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0034] This invention provides a method for preparing a highly sensitive, one-step electrochemical sensor for detecting multi-component heavy metal ions, the method comprising the following steps:

[0035] (1) Polish the glassy carbon electrode (GCE) on chamois for about 1 to 2 minutes with Al2O3 polishing powder, and then clean the electrode with ultrapure water; drop GDY suspension is applied to the surface of GCE, and after drying, the modified electrode GDY / GCE is obtained.

[0036] (2) Continue to immerse GDY / GCE in bismuth salt solution, electrodeposit bismuth film, and then dry with nitrogen to obtain modified electrode Bi / GDY / GCE.

[0037] In step (1), the GDY / GCE preparation process is as follows: 5 μL of GDY suspension with a concentration of 5.0 mg / mL is dropped onto the treated GCE surface and dried with an infrared lamp to obtain the modified electrode GDY / GCE.

[0038] In step (2), the process of electrodepositing bismuth film is as follows: GDY / GCE is immersed in an aqueous solution of 0.1 mM Bi(NO3)3, Ag / AgCl is used as the reference electrode, and a platinum wire electrode is used as the counter electrode. The deposition potential is -1.1 V and the deposition time is 120 s.

[0039] The present invention also provides an electrochemical sensor for one-step detection of the concentration of multiple heavy metal ions in an aquatic environment, which is prepared by the above method.

[0040] The present invention also provides a method for one-step detection of Zn in an aquatic environment. 2+ Cd 2+ and Pb 2+ An electrochemical sensor for detecting the concentration of Zn in an aqueous environment was used. The detection method employed a three-electrode system, with Bi / GDY / GCE as the working electrode, Ag / AgCl as the reference electrode, and platinum wire as the counter electrode. Adsorption-stripping voltammetry was used to detect Zn in the aqueous environment. 2+ Cd 2+ and Pb 2+ The test was performed. First, a series of Zn samples of different concentrations were enriched under constant potential while stirring. 2+ Cd 2+ Pb 2+ Standard buffer solution is used, followed by dissolution, to obtain the anodic dissolution peak current. The magnitude of the anodic dissolution peak current is then compared with that of Zn. 2+ Cd 2+ Pb 2+ Logarithmic curves were plotted for the concentrations of each ion in the standard buffer solution. These curves were then used to analyze the Zn concentration in the aquatic environment. 2+ Cd 2+ Pb 2+ Conduct testing.

[0041] Example 1:

[0042] The preparation method of an electrochemical sensor for one-step detection of multi-component heavy metal ions is as follows:

[0043] (1) Pretreatment of glassy carbon electrode. First, the glassy carbon electrode was polished on chamois with Al2O3 polishing powder of 0.3 μm, 0.1 μm and 0.05 μm respectively. Then, it was ultrasonicated with water, ethanol and water for 3 min respectively. Finally, the electrode was rinsed with ultrapure water and dried with nitrogen gas for later use.

[0044] (2) Preparation of GDY / GCE. GDY was sonicated in ultrapure water for 30 min to form a uniform suspension of 5.0 mg / mL GDY. 5 μL of the GDY suspension was drop-coated onto the pretreated GCE surface and dried with an infrared lamp to obtain the GDY / GCE modified electrode.

[0045] (3) Preparation of Bi / GDY / GCE. In a three-electrode system with GDY / GCE as the working electrode, Ag / AgCl as the reference electrode, and a platinum wire electrode as the counter electrode, a 0.1 mM Bi(NO3)3 solution was used as the electrolyte solution. Bismuth film was electrodeposited on the surface of GDY / GCE by chronoamperometry (it). The deposition potential was -1.1 V and the deposition time was 120 s. The film was then washed with ultrapure water and dried with nitrogen to obtain the modified electrode Bi / GDY / GCE.

[0046] Example 2:

[0047] The Bi / GDY / GCE electrochemical sensor prepared in Example 1 was used to detect Zn. 2+ Cd 2+ Pb 2+ One step of the detection.

[0048] Zn was analyzed by adsorption-stripping voltammetry 2+ Cd 2+ and Pb 2+ Concentration was determined in a single step using a three-electrode system, with Bi / GDY / GCE as the working electrode, Ag / AgCl as the reference electrode, and platinum wire as the counter electrode. First, a series of Zn concentrations were enriched at a constant potential under stirring conditions. 2+ Cd 2+ Pb 2+ A standard buffer solution was used, with an enrichment potential of -1.3 V and an enrichment time of 150 s. The buffer solution was HAc-NaAc at pH 6.0. Dissolution was then performed, with the dissolution potential scanned from -1.3 V to 0.2 V, yielding the anodic dissolution peak current. The peak current value increased with increasing heavy metal ion concentration, due to the increased amount of heavy metal ions adsorbed onto the Bi / GDY / GCE surface. The magnitude of the anodic dissolution peak current was correlated with Zn... 2+ Cd 2+ Pb 2+ Plotting the logarithms of the concentrations of each ion in the standard buffer solution to obtain a working curve for Zn in the aquatic environment. 2+ Cd 2+ Pb 2+ Quantitative detection was performed, with detection limits of 1.46 pM, 1.15 pM, and 1.71 pM, and a linear range of 100 pM - 100 μM.

[0049] Example 3:

[0050] The selectivity and stability of the Bi / GDY / GCE electrochemical sensor prepared in Example 1 were tested.

[0051] Zn was analyzed by adsorption-stripping voltammetry 2+ Cd2+ and Pb 2+ A further step of detection was performed to selectively measure the Bi / GDY / GCE electrochemical sensor of this invention. The method was as follows: a solution containing other interfering ions was added to a solution containing Zn. 2+ Cd 2+ Pb 2 + In HAc-NaAc, adsorption-stripping voltammetry was performed under the same conditions and using the same method described above to study the changes in the characteristic peak potentials and peak currents of the anodic dissolution of three heavy metal ions, and to examine the selectivity of the electrochemical sensor. The interfering ion was Ni. 2+ Co 2+ Fe 3+ Cu 2+ Fe 2+ Mg 2+ Ca 2+ Mn 2+ or Cl - The concentration was 100 μM. After the addition of interfering ions, Zn... 2+ Cd 2+ Pb 2+ The peak potential deviation was 3.6%, the peak position did not change significantly, and no other dissolution peaks appeared, indicating that the electrochemical sensor has good selectivity. Further stability testing of the Bi / GDY / GCE electrochemical sensor of this invention was conducted. The prepared Bi / GDY / GCE was stored in a refrigerator at 4°C for 6 days, and adsorption-dissolution voltammetry was performed daily under the same conditions using the same method described above to study Zn. 2+ Cd 2+ Pb 2+ The stability of the electrochemical sensor was investigated by examining the changes in the characteristic peak potential and peak current of anodic dissolution. The peak current RSD was 5.2%, indicating that the electrochemical sensor exhibits good stability in a 4°C refrigerator.

[0052] Test Example 1

[0053] The GCE (a), GDY / GCE (b), Bi / GCE (c), and Bi / GDY / GCE (d) prepared in Example 1 were used as working electrodes, the Ag / AgCl electrode was used as the reference electrode, and the platinum wire was used as the counter electrode. The three electrodes were placed in an electrolyte solution, and electrochemical tests were performed using cyclic voltammetry and adsorption-stripping voltammetry.

[0054] Figure 1 The cyclic voltammetry curves of GDY / GCE prepared in Example 1 at different scan rates in a mixed electrolyte of 1 mM K3[Fe(CN)6] and 0.5 M KCl are shown below. Figure 1It can be seen that as the scan rate increases, the redox peak potential shifts to the positive and negative directions, respectively, and the redox peak current also gradually increases with the increase of the scan rate.

[0055] Figure 2 To obtain the oxidation peak current and υ of the prepared GDY / GCE at different scan rates 1 / 2 The linear relationship, from Figure 2 It can be seen that the redox peak current and υ 1 / 2 A good linear relationship is formed. Calculations show that the effective area of ​​GDY / GCE is 0.162 cm². 2 .

[0056] Figure 3 GCE, GDY / GCE, Bi / GCE, and Bi / GDY / GCE prepared in Example 1 were subjected to 100 μM Zn 2+ Cd 2+ Pb 2+ Adsorption-dissolution voltammetry curves in a HAc-NaAc (pH 6.0) mixed electrolyte. (Example:) Figure 3 As shown, the peak current changes between bare GCE (curve a) and GDY / GCE (curve b) are not significant. The peak current signal of Bi / GCE (curve d) is increased compared to curves a and b, indicating that the bismuth film is beneficial for Zn production. 2+ Cd 2+ Pb 2+ The deposition of bismuth on the electrode surface enhances the dissolution signal of the analyte ions. The significant increase in the peak current of Bi / GDY / GCE (curve d) is due to the synergistic effect of the deposited bismuth film and GDY. GDY effectively increases the electrode surface area, which is beneficial for the formation of an alloy between the analyte metal ions and the bismuth element on the electrode surface, thereby increasing the dissolution signal of Zn. 2+ Cd 2+ Pb 2+ The dissolution signal on Bi / GDY / GCE is significantly increased.

[0057] Figure 4 This is an optimization plot showing the drop volume corresponding to the 5.0 mg / mL GDY suspension described in Example 1. Drop volumes of 1 μL, 2 μL, 3 μL, 4 μL, 5 μL, 6 μL, and 7 μL were used, and seven GDY / GCE electrodes were obtained by drying under an infrared lamp. Next, electrodes containing 100 μM Zn... 2+ Cd 2+ Pb 2+ The electrochemical performance of the electrode was tested using adsorption-stripping voltammetry in a HAc-NaAc (pH 6.0) mixed electrolyte. The enrichment potential was -1.3 V, and the enrichment time was 150 s. The results indicate that the optimal volume for drop-coating the GDY suspension is 5 μL.

[0058] Test Example 2

[0059] Figure 5 This is an optimization diagram corresponding to the types of buffer solutions in Example 2. This experiment optimized four buffer solutions: BR, HAc-NaAc, PBS, and Tris-HCl. The test results are as follows... Figure 5 As shown, Bi / GDY / GCE exhibits the highest dissolution signal in HAc-NaAc, therefore HAc-NaAc was selected as the optimal buffer environment in this experiment.

[0060] Figure 6 This is the pH optimization diagram corresponding to HAc-NaAc in Example 2. In this experiment, the detection performance of Bi / GDY / GCE was tested in HAc-NaAc at pH values ​​of 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, and 6.5. The results are as follows... Figure 6 As shown, Bi / GDY / GCE exhibited the highest dissolution signal when the pH value of HAc-NaAc was 6.0. Therefore, 6.0 was selected as the optimal pH value in this experiment.

[0061] Figure 7 For example, Zn corresponding to Example 2 2+ Cd 2+ Pb 2+ The enrichment potential optimization diagram is shown. In this experiment, Bi / GDY / GCE was used to enrich the solution in the test solution at potentials of -0.9, -1.0, -1.1, -1.2, -1.3, -1.4, and -1.5 V for 150 s, and the dissolution signal was detected. The results are as follows. Figure 7 As shown, Bi / GDY / GCE exhibits the highest dissolution signal when the enrichment potential is -1.3 V. Therefore, -1.3 V was selected as the optimal enrichment potential in this experiment.

[0062] Figure 8 For example, Zn corresponding to Example 2 2+ Cd 2+ Pb 2+ The enrichment time optimization diagram is shown. In this experiment, Bi / GDY / GCE was used to enrich the test solution at a potential of -1.3 V for 60 s, 90 s, 120 s, 150 s, 180 s, 210 s, and 240 s, respectively, and the dissolution signal was detected. The results are as follows. Figure 8 As shown, Bi / GDY / GCE exhibited the highest dissolution signal when the enrichment time was 150 s. Therefore, 150 s was selected as the optimal enrichment time in this experiment.

[0063] Figure 9Bi / GDY / GCE prepared in Example 2 were prepared at Zn concentrations of 100 pM, 1 nM, 10 nM, 100 nM, 1 μM, 2 μM, 4 μM, 6 μM, 8 μM, 10 μM, 20 μM, 40 μM, 60 μM, 80 μM, and 100 μM. 2+ Cd 2+ Pb 2+ Adsorption-dissolution voltammetry curves in the mixed electrolyte. Results are as follows: Figure 9 As shown, the current signal increases with increasing metal ion concentration, indicating that Bi / GDY / GCE has good one-step detection properties for Zn. 2+ Cd 2+ Pb 2+ The ability.

[0064] Figure 10 Bi / GDY / GCE prepared with Zn at different concentrations 2+ Cd 2+ Pb 2+ The dissolution peak current in the electrolyte solution and log C The linear relationship, from Figure 10 It can be seen that the peak current is related to log C It showed a good linear relationship, with detection limits of 1.46 pM, 1.15 pM, and 1.71 pM, respectively, and a linear range of 100 pM - 100 μM.

[0065] Test Example 3

[0066] Figure 11 The Bi / GDY / GCE prepared in Example 3 was used in an electrochemical sensor, regardless of whether it contained interfering ions (Ni). 2+ Co 2 + Fe 3+ Cu 2+ Fe 2+ Mg 2+ Ca 2+ Mn 2+ or Cl - Zn 2+ Cd 2+ Pb 2+ Adsorption-dissolution voltammetry curves were obtained in the mixed electrolyte, with ion concentrations of 100 μM. The results are as follows: Figure 11 As shown, Zn 2+ Cd 2+ Pb 2+ The deviation of the dissolution peak current was no more than 3.6%, the peak position did not change significantly, and no other dissolution peaks appeared, indicating that the electrochemical sensor has good selectivity.

[0067] Figure 12 The Bi / GDY / GCE prepared in Example 3 was stored in a refrigerator at 4°C for 6 days. Adsorption-dissolution voltammetry was performed daily under the same conditions and using the same method described above to investigate the stability of the electrochemical sensor. The results are as follows: Figure 12 As shown, Zn 2+ Cd 2+ Pb 2+ The RSD of the dissolution peak current is 5.2%, indicating that the electrochemical sensor has good stability in a 4℃ refrigerator.

[0068] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. Application of bismuth film and two-dimensional GDY sensor in one-step detection of multi-component heavy metal ions, characterized in that, The preparation method of the bismuth film and two-dimensional GDY sensor comprises the following steps: (1) polishing the glassy carbon electrode on the buffing leather with Al2O3 polishing powder for 1-2 minutes, and then cleaning the electrode with ultrapure water; dropping and coating GDY suspension on the surface of the GCE, and obtaining the modified electrode GDY / GCE after drying; (2) immersing the modified electrode GDY / GCE obtained in step (1) into a bismuth salt solution, electrodepositing a bismuth film, and then drying with nitrogen to obtain the modified electrode Bi / GDY / GCE; (3) The modified electrode Bi / GDY / GCE obtained in step (2) is immersed in a mixed electrolyte solution of Zn 2+ , Cd 2+ , Pb 2+ , and the elution electrochemical signal of the sample to be tested is detected by adsorptive stripping voltammetry. The GDY suspension in step (1) has a concentration of 5.0 mg / mL, and the dropping and coating volume is 5 μL; the drying is infrared lamp drying; The preparation process of the GDY suspension is as follows: adding ultrapure water into GDY, and then using a cell pulverizer to ultrasonically treat for 30 min to obtain a 5.0 mg / mL GDY uniform suspension; The bismuth salt solution in step (2) is a 0.1 mM Bi(NO3)3 solution; the method for electrodepositing the bismuth film is chronoamperometry, the deposition potential is-1.1 V, and the deposition time is 120 s; Zn 2+ , Cd 2+ , Pb 2+ The concentration of metal ions in the mixed electrolyte solution was 100 pM-100 μM, and the buffer solution was acetic acid-sodium acetate at pH 6.

0. The adsorptive stripping voltammetry in step (3) is as follows: using a three-electrode system, taking the sensor as a working electrode, Ag / AgCl as a reference electrode, and a platinum wire as a counter electrode, the enrichment potential of the adsorptive stripping voltammetry is-1.3 V, and the enrichment time is 150 s.

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