CN110441358B

CN110441358B - Method for detecting iodide ions based on graphene/gold @ silver nanoparticle modified electrode

Info

Publication number: CN110441358B
Application number: CN201910622119.5A
Authority: CN
Inventors: 周川华; 赵文颖; 吴冰燕; 吴凡; 沈礼鸿; 曹秋娥
Original assignee: Yunnan University YNU
Current assignee: Yunnan University YNU
Priority date: 2019-07-10
Filing date: 2019-07-10
Publication date: 2021-08-13
Anticipated expiration: 2039-07-10
Also published as: CN110441358A

Abstract

The invention relates to a method for detecting iodide ions based on a graphene/gold @ silver nanoparticle modified electrode, and belongs to the technical field of analysis and detection. The method comprises the steps of firstly preparing a graphene/gold @ silver nanoparticle modified electrode, and then utilizing iodide ions (I)^‑) Silver simple substances on the surface of the electrode can be oxidized into silver iodide in the presence of copper ions, and the detection of target iodide ions is realized by utilizing the reduction of stripping voltammetric signals of silver on the surface of the modified electrode. The method combines the redox reaction with the electrochemical stripping voltammetry detection method, has very high detection sensitivity, has the advantages of simple operation, strong specificity, high sensitivity and no need of complex instruments, and can be applied to the high-sensitivity detection of iodide ions in practical samples.

Description

Method for detecting iodide ions based on graphene/gold @ silver nanoparticle modified electrode

Technical Field

The invention belongs to the technical field of analysis and detection, and particularly relates to a method for detecting iodide ions based on a graphene/gold @ silver nanoparticle modified electrode.

Background

Iodine is an indispensable component of thyroid hormone and plays a crucial role in regulating cell metabolism, muscle tissue growth and neural development, and the iodine deficiency or excessive iodine intake of a human body can cause a great health problem. For example, iodine deficiency during pregnancy can lead to fetal goiter, cretinism, dysnoesia and hypothyroidism in newborns, while excess iodine can lead to hyperthyroidism. Therefore, the development of a simple, rapid and sensitive method for detecting iodide ions is of great significance. Up to now, various methods have been successfully applied to the detection of iodide ions, such as inductively coupled plasma mass spectrometry, chromatography, capillary electrophoresis, surface enhanced raman scattering, atomic absorption spectroscopy, and the like. In practical use, the methods have certain defects, such as high detection cost, complex operation, long time consumption, requirement of precise instruments, well-trained operators and complex sample pretreatment process. The electrochemical method has the advantages of low detection cost, simple instrument and equipment, time saving, simple operation and the like, and for example, the fluorine ion selective electrode is widely applied to the rapid detection of fluorine ions. However, compared with other halogen ions, the volume of iodide ions is larger and the alkalinity is lower, so that the development of an electrochemical detection method for detecting iodide ions with high sensitivity still has great challenges.

Disclosure of Invention

In order to solve the defects of the prior art, the invention provides a method for detecting iodide ions based on a graphene/gold @ silver nanoparticle modified electrode, the method adopts the graphene/gold @ silver nanoparticle modified electrode as a working electrode, combines an oxidation-reduction reaction and an electrochemical stripping voltammetry detection means, utilizes iodide ions to oxidize silver simple substances on the surface of the electrode into silver iodide in the presence of copper ions, and realizes rapid and high-sensitive detection of the iodide ions by reducing stripping voltammetry signals of silver on the surface of the working electrode.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a preparation method of a graphene/gold @ silver nanoparticle modified electrode for iodine ion detection comprises the following steps:

step (1), taking 1mg/mL graphene oxide suspension drops as a modification solution, coating the modification solution on the surface of a cleaned electrode, and naturally airing the electrode;

the electrode is a glassy carbon electrode, and the dosage of the modification solution is 0.71 mu L/mm²Taking 5 mu L of modification solution corresponding to an electrode with the diameter of 3 mm;

step (2), the electrode treated in the step (1) is placed in 0.1mol/L KH₂PO₄In the solution, reducing for 600s at a constant potential of-0.8V, and reducing the graphene oxide on the surface of the electrode to obtain a graphene modified electrode;

a step (3) of,placing the graphene modified electrode in 5mmol/L HAuCl₄In the solution, applying a potential of-0.2V to reduce for 60s to obtain a graphene/nano gold modified electrode;

step (4), sequentially taking 5 mu L of 0.05mol/L AgNO₃485 mu L of 0.1mol/L of 9.8 diethanolamine-HNO solution₃And (3) uniformly mixing the buffer solution and 10 mu L of 1mmol/L ascorbic acid, quickly soaking the graphene/nano-gold modified electrode in the mixed solution, and reacting for 5min in a dark place at 37 ℃ to obtain the graphene/gold @ silver nano-particle modified electrode for iodine ion detection.

Further, it is preferable that the glassy carbon electrode is polished on a wet chamois with 0.5 μm and 0.05 μm alumina powders, respectively, to a mirror surface, after which each lmin is ultrasonically cleaned with ultrapure water, absolute ethyl alcohol, and ultrapure water in this order, and then the glassy carbon electrode is placed in a 1mmol/L potassium ferricyanide solution, and cyclic voltammetry scanning is performed in a potential range of-0.2V to 0.6V, indicating that the glassy carbon electrode is cleaned when a potential difference of an oxidation reduction peak of potassium ferricyanide is 80mV or less.

The invention also provides an application of the graphene/gold @ silver nanoparticle modified electrode for detecting iodide ions in detection of iodide ions.

The invention provides an application of a graphene/gold @ silver nanoparticle modified electrode for detecting iodide ions, which comprises the following steps:

step (1), adding iodine ion-containing solution to be detected into phosphoric acid buffer solution containing copper sulfate according to the mass ratio of 1:1 to obtain reaction solution;

the phosphoric acid buffer solution containing copper sulfate comprises: 0.4mmol/L copper sulfate and 0.2mol/L phosphoric acid buffer with pH 7.2, the solvent is water;

inserting a graphene/gold @ silver nanoparticle modified electrode serving as a working electrode into the reaction solution obtained in the step (1), reacting for 20 minutes in a dark place at 37 ℃, washing the working electrode with ultrapure water, placing the washed working electrode into a 1mol/L KCl aqueous solution for linear voltammetry scanning determination, and quantifying iodide ions by adopting a standard curve method according to the detected intensity of an oxidation signal of silver;

further, it is preferable that the sweep range of the linear voltammetric sweep is-0.2 to 0.4V and the sweep rate is 100 mV/s.

Compared with the prior art, the invention has the beneficial effects that:

1. the detection method comprises the steps of adding a solution to be detected containing iodine ions into a phosphoric acid buffer solution containing copper sulfate, inserting the graphene/gold @ silver nanoparticle modified electrode into the reaction solution for incubation, and oxidizing a silver simple substance on the surface of the electrode into silver iodide in the presence of the iodine ions, so that the reduction of a stripping voltammetry signal of silver on the surface of the modified electrode can be utilized to realize the purpose of I target^-Detection of (3).

2. The invention combines redox reaction and electrochemical detection, establishes a simple and high-sensitivity electrochemical detection method and applies the method to I^-Specific detection of (3). The invention combines redox reaction, iodine ions convert silver simple substance on the surface of the electrode into silver iodide through redox reaction, and the reduction of stripping voltammetry signal of silver on the surface of the electrode is modified to realize I^-The overall strategy effectively amplifies the detection sensitivity of the method; the graphene/gold @ silver nanoparticle modified electrode is used as a working electrode, so that the detection sensitivity can be further amplified.

3. The method combines a chemically modified electrode, redox reaction and metal stripping voltammetry, and utilizes the fact that I is carried out in the presence of copper ions^-Silver elementary substance on the surface of the modified electrode can be converted into silver iodide through oxidation-reduction reaction, and the I can be reduced by utilizing stripping voltammetry signals of silver on the surface of the modified electrode^-The detection sensitivity of the method can be effectively improved by the strategy.

4. The invention carries out quantitative detection on alkaline phosphatase by reducing stripping voltammetry signals (delta I) of silver on the surface of a modified electrode, I^-The concentration and the delta I are linearly related between 0.01 mu mol/L and 20 mu mol/L, the detection limit is 4.6nmol/L, and the method is proved to have very high detection sensitivity.

5. The method also has good specificity and anti-interference capability, and can realize the detection of iodide ions in actual samples.

6. The method has the advantages of simple and rapid operation, simple instrument, good specificity, low detection limit, strong practicability and the like, and can be used for preparing iodide ions (I)^-) The detection field of the method has wide application prospect.

Drawings

Fig. 1 is a schematic diagram illustrating the principle of detecting iodide ions according to the present invention.

FIG. 2 shows the use of AgNO at different concentrations₃Detection I of prepared graphene/gold @ silver nanoparticle modified glassy carbon electrode^-A comparison graph of stripping voltammetry signals of silver on the surfaces of front and back electrodes, wherein a represents I^-Stripping voltammetric signal of silver before reaction; b represents a molar ratio of 10. mu. mol/L I^-Stripping voltammetric signal of silver after reaction.

FIG. 3 is a scanning electron microscope representation of the electrode surface; wherein (A) a bare glassy carbon electrode; (B) modifying a glassy carbon electrode by using graphene; (C) modifying a glassy carbon electrode by using graphene/gold @ silver nanoparticles; (D) detection of 10 mu mol/L I by using graphene/gold @ silver nanoparticle modified glassy carbon electrode^-The rear electrode surface.

FIG. 4 shows the different detection conditions for I^-Detecting the effect of the signal Δ I, wherein (a) is the effect of the reaction temperature; (B) as a function of reaction time; (C) the influence of buffer pH; (D) the effect of copper ion concentration.

FIG. 5 shows the detection of different concentrations I by the present method^-The resulting electrochemical signal, wherein (A) detects I at various concentrations^-Stripping voltammetric signal profile of silver from the surface of a time electrode, I^-The concentration is as follows in sequence: (a)0 μmol/L, (b)0.01 μmol/L, (c)0.10 μmol/L, (d)1.0 μmol/L, (e)10 μmol/L, (f)20 μmol/L, (g)30 μmol/L, (h)40 μmol/L; (B) detecting I at different concentrations^-And (4) a graph of the change of the difference value delta I of stripping voltammetric signals of silver on the surfaces of the front electrode and the rear electrode (an inset graph is a linear fitting curve).

FIG. 6 shows this method pair I^-The specificity histogram (the concentration of each ion in the graph is 10. mu. mol/L).

FIG. 7 shows the detection of 10. mu. mol/L I for different modified electrodes^-Comparison of the obtained detection signals, thereofA in (A) represents^-Stripping voltammetric signals of different electrode silver before reaction; b represents and I^-Stripping voltammetric signal of silver after reaction.

Detailed Description

The present invention will be described in further detail with reference to examples.

It will be appreciated by those skilled in the art that the following examples are illustrative of the invention only and should not be taken as limiting the scope of the invention. The examples do not specify particular techniques or conditions, and are performed according to the techniques or conditions described in the literature in the art or according to the product specifications. The materials or equipment used are not indicated by manufacturers, and all are conventional products available by purchase.

Example 1: and (4) detecting iodide ions.

The following describes the electrochemical detection method based on Au @ Ag nanoparticle etching in detail by taking the detection of iodide ions as an example.

1. Modification of electrodes

A bare glassy carbon electrode having a diameter of 3mm was polished to a mirror surface by polishing a wet chamois with 0.5 μm and 0.05 μm alumina powders in this order. And ultrasonically cleaning each lmin by using ultrapure water, absolute ethyl alcohol and ultrapure water in sequence. And then placing the glassy carbon electrode in a 1mmol/L potassium ferricyanide solution, and carrying out cyclic voltammetry scanning within a potential range of-0.2V-0.6V, wherein when the potential difference of an oxidation reduction peak of potassium ferricyanide is below 80mV, the glassy carbon electrode is cleaned.

Weighing a certain amount of graphene oxide, and dispersing the graphene oxide in ultrapure water to prepare a 1mg/mL graphene oxide aqueous solution. 5 mu L of the graphene oxide aqueous solution is dripped on the surface of a glassy carbon electrode which is cleaned; naturally drying, and placing at 0.1mol/L KH₂PO₄In the solution, reducing and oxidizing graphene for 600s at a constant potential of-0.8V to obtain a graphene modified electrode; then placing the graphene modified electrode in 5mmol/L HAuCl₄And (3) in the solution, applying a potential of-0.2V to reduce for 60s to prepare the graphene/nano gold modified electrode.

Sequentially taking 5 mu L of 0.05mol/L AgNO₃485 mu L of 0.1mol/L of 9.8 diethanolamine-HNO solution₃And (3) uniformly mixing the buffer solution and 10 mu L of 0.001mol/L ascorbic acid solution, quickly soaking the graphene/nano-gold modified electrode in the mixed solution, and reacting for 5min in a dark place at 37 ℃ to obtain the modified electrode (graphene/gold @ silver nano-particle modified electrode) for detecting iodide ions.

2. Detection of iodide ions

250 μ L of a suspension containing I^-To 250. mu.L of a solution containing 0.4mmol/L of CuSO₄And (3) uniformly mixing the solution in a phosphoric acid buffer solution (0.2mol/L, pH 7.2), then placing the graphene/gold @ silver nanoparticle modified electrode serving as a working electrode in the mixed solution for soaking, and carrying out a light-shielding reaction at 32 ℃ for 20 min. Then the working electrode is taken out and is placed in a 1mol/L KCl solution after being washed by ultrapure water, and scanning is carried out from-0.2V to 0.4V by a linear voltammetry (LSV) scanning method (the scanning speed is 100mV/s), so as to obtain stripping voltammetry signals of the silver on the surface of the electrode.

Using the above method on a series of known concentrations of I^-Detecting, drawing a standard curve, and measuring the electrochemical signal obtained by detecting the sample to be detected according to the I corresponding to the standard curve^-Concentration to realize the pair I^-And (4) carrying out quantitative detection.

3. Experiment of specificity

To examine the specificity of the method, interfering ions which may be present in the actual sample, e.g.10. mu. mol/L F, are used^-、Cl^-、Br^-、NO₃ ^-、SO₄ ^2-、CO₃ ^2-、HPO₄ ^2-As a negative control, the detection was carried out by the method described in step 2.

4. In actual sample I^-Detection of (2)

Diluting drinking mineral water with ultrapure water ten times, treating tap water, and directly adopting the method in the step 2 to treat the mineral water I^-And (6) detecting. In addition, a certain amount of I^-The recovery rate of the added standard is measured by adding the added standard into the actual sample.

Second, result in

1. Principle of detection

FIG. 1 is the process pair I^-The detection principle of the method is shown in a schematic diagram, a graphene/gold @ silver nanoparticle modified electrode is used as a working electrode, and when I does not exist in a solution^-Then, Cu in the liquid is detected²⁺Silver on the surface of the electrode cannot be oxidized, and therefore, a relatively large stripping voltammetric signal of silver can be detected. When detecting I in the liquid^-And Cu²⁺When existing at the same time, the following oxidation-reduction reactions mainly occur on the surface of the electrode:

2Cu²⁺+4I^-＝2CuI+I₂ (1)

2Ag+I₂＝2AgI (2)

detecting I in a liquid^-Can be in Cu²⁺The silver on the surface of the electrode is oxidized into AgI in the presence of the silver, and the stripping voltammetry signal of the silver on the surface of the electrode is reduced. Due to the fact that

Is less than

So Cu in the solution²⁺Ag incapable of oxidizing electrode surface⁰. Although it is not limited to

Ratio of

Low, but because the generation of CuI enables

(0.860V) is significantly increased, thereby making Cu²⁺Capable of oxidizing I^-Generation of I₂. Therefore, in Cu²⁺In the presence of^-Can be oxidized to I₂(reaction 1), I produced₂Further Ag on the electrode⁰The oxidation-reduction reaction occurs to generate AgI (reaction 2), so that the stripping voltammetry signal of the silver on the electrode is reduced, and therefore, the silver on the surface of the electrode can be utilizedReduction of stripping voltammetric signal to achieve p-I^-Detection of (3).

2. Optimization of electrode modification conditions

Since the method is based on I^-The electrochemical detection method established by the redox reaction with the silver on the surface of the electrode has important influence on the sensitivity, detection limit and the like of the method by the modified electrode. According to the invention, the graphene/gold @ silver nanoparticle modified electrode is used as a working electrode, and as the thickness of a silver layer on the surface of the electrode has the greatest influence on a detection signal, the thickness of a silver shell layer on the surface of the graphene/gold @ silver nanoparticle modified electrode is controlled by controlling the concentration of silver nitrate during reaction with ascorbic acid.

When the graphene/gold @ silver nanoparticle modified electrode is prepared, the reaction temperature, the reaction time and the concentration of ascorbic acid are fixed, the concentration of silver nitrate is changed, a stripping voltammetry signal of silver on the surface of the prepared graphene/gold @ silver nanoparticle modified electrode is detected, and the stripping voltammetry signal is compared with a silver stripping voltammetry signal obtained by detecting a 10 mu mol/L sodium iodide solution. The detection result is shown in fig. 2, when the silver nitrate concentration is 0.1mmol/L, the silver layer on the surface of the electrode is too thin, so that the silver on the surface of the electrode is completely etched, and the detection range is too narrow under the condition; when the concentration of silver nitrate is 1mmol/L, the silver layer on the surface of the electrode is too thick, so that I in a low concentration range^-The silver etching on the surface of the electrode is not obvious, and the detection sensitivity can be reduced under the condition; when the concentration of silver nitrate is 0.5mmol/L, the same concentration I^-The silver on the surface of the electrode is etched most obviously, and the difference value of stripping voltammetric signals of the silver on the surface of the electrode before and after etching is maximum, so that the detection sensitivity of the method is improved, and the detection limit is reduced. Therefore, the silver nitrate concentration for preparing the graphene/gold @ silver nanoparticle modified electrode is selected to be 0.5 mmol/L.

3. Characterization of electrodes

The different electrodes were characterized by scanning electron microscopy, the results are shown in fig. 3. It can be seen from the figure that the surface of the bare glassy carbon electrode without any modification is smooth and flat (fig. 3A), and the graphene is modified on the electrode, so that the surface of the electrode has an obvious graphene film layer (fig. 3B). Plating gold nanoparticles on the electrodesAfter silver ions are reduced by ascorbic acid to form Au @ Ag nanoparticles, it can be seen from a scanning electron micrograph that nanoparticles with uniform particle size are uniformly distributed on the surface of the graphene film (fig. 3C). When graphene/gold @ silver nanoparticle modified electrode is used for detecting I^-Later, the nanoparticles on the electrode surface became significantly smaller and denser (fig. 3D). Shows that the silver on the surface of the electrode modified by the graphene/gold @ silver nano particles can react with I in the presence of copper ions^-The reaction is carried out, and the result can laterally prove that the graphene/gold @ silver nanoparticle modified electrode is successfully prepared and can utilize I^-The specific reaction with graphene/gold @ silver nano-particle modified electrode surface silver is realized to realize I^-Detection of (2)

4. Optimization of detection conditions

To increase the sensitivity of the detection, influence I^-And the surface of the electrode Ag⁰The factors of the reaction, such as reaction temperature, time, solution pH, Cu, were studied²⁺Concentration, etc.

Firstly, for the detection I^-The reaction temperature is optimized, and under the condition that other reaction conditions are not changed, 1 mu mol/L sodium iodide solution is detected at different reaction temperatures. Experiments show that when the temperature is lower than 32 ℃, the reaction temperature is increased along with I^-The difference value delta I of stripping voltammetric signals of silver on the surface of the electrode before and after reaction is gradually increased; at temperatures above 32 ℃, Δ I becomes increasingly smaller again (fig. 4A). Detecting iodine ion (I) of the same concentration^-) When with I^-The larger the difference delta I of stripping voltammetric signals of silver on the surfaces of the electrodes before and after reaction indicates that the sensitivity of the detection method is higher, so that the detection I is selected to be 32 DEG C^-The optimum reaction temperature of (a).

Reaction time is optimized, other reaction conditions are fixed, and the graphene/gold @ silver nano-particle modified electrode is mixed with 1 mu mol/L I in detection liquid^-The reaction was carried out for various times. As shown in FIG. 4B, the Δ I gradually increases with the increase of the reaction time, and the detection signal Δ I substantially becomes stable after the reaction time reaches 20 min. Therefore, 20min was selected as the optimal reaction time for detecting iodide ions.

The pH of the reaction solution is optimized, the reaction is carried out in PBS buffer solutions with different pH values under the condition that other reaction conditions are not changed, and experiments show that the graphene/gold @ silver nanoparticle modified electrode pair is 1 mu mol/L I in the range of pH 5.8-8.0^-Since the detection signal Δ I of (1) is substantially constant (fig. 4C), the pH value has substantially no effect on the reaction when the pH is 5.8 to 8.0, and therefore, a phosphate buffer solution of pH 7.2 is selected as the reaction pH condition for detecting iodide ions.

But also for Cu in the reaction solution²⁺The concentration is optimized. Under the condition that other conditions are not changed, the CuSO of the electrode at different concentrations is modified by utilizing the graphene/gold @ silver nano particles₄With 1. mu. mol/L of I in solution^-The reaction is carried out. The results are shown in FIG. 4D, the concentration range is 0.01 mmol/L-0.30 mmol/L Cu²⁺To I^-The detection signal Δ I of (1) has substantially no influence, and the results also laterally demonstrate Cu²⁺Ag on the surface of the electrode cannot be oxidized per se⁰. Therefore, the concentration of copper ions in the reaction solution for detecting iodide ions was selected to be 0.2 mmol/L.

5、I^-Detection of (2)

Under the optimal reaction condition, stripping voltammetry is adopted to process the material containing different concentrations of I^-The test results are shown in FIG. 5A, with I^-The concentration of the silver on the surface of the electrode is increased, the stripping voltammetric signal of the silver on the surface of the electrode is gradually reduced, I^-The logarithm of the concentration is in a good linear relationship with Δ I in the concentration range of 0.01 μmol/L to 20 μmol/L (FIG. 5B inset, R)²0.994). The detection limit of the method was calculated from 3 σ and found to be 4.6nmol/L (S/N — 3). Relative to the literature reported I^-The detection method has higher detection sensitivity and lower detection limit.

6. Specificity of

To verify the specificity of the method, interfering ions that may be present in the actual sample are used, such as: f^-、Cl^-、Br^-、NO₃ ^-、SO₄ ^2-、CO₃ ^2-、HPO₄ ^2-(the concentration is 10 mu mol/L) as a negative control, the test paper was usedThe method is used for detection and is equal to the concentration I^-Is compared. The detection result is shown in FIG. 6, under the same detection condition, only a small background signal can be obtained for various interfering ions, only in I^-The silver on the surface of the electrode can be etched in the presence of the silver. Indicating the method of the pair I^-Has good selectivity in detection.

7. In actual sample I^-Detection of (2)

To examine the practicability of this experimental method, edible mineral water (which has a high iodine ion content because it is mountain spring water and is diluted ten times and then detected) and iodine ions (I) in tap water were measured^-) The results of the tests are shown in Table 1. The recovery rate of the sample is 94.20-107.4%, the relative standard deviation is less than 5.00%, and the method meets the requirement of practical analysis, and shows that the method can be applied to the I in practical samples^-Detection of (3).

TABLE 1 actual samples I^-Result of detection of

8. Signal amplification effect of modified electrode

In order to verify the signal amplification effect of each modification material on the surface of the graphene/gold @ silver nanoparticle modified electrode in the method, different nanoparticles are modified on the surface of the glassy carbon electrode by adopting a modification method similar to that of the electrode to obtain different modified electrodes (such as a silver nanoparticle modified glassy carbon electrode (AgNPs/GCE), a graphene/silver nanoparticle modified glassy carbon electrode (AgNPs/graphene/GCE) and a gold and silver nanoparticle modified glassy carbon electrode (Au @ AgNPs/GCE) which are used as references, and the three different modified electrodes are used for 10 mu mol/L I of 10 mu mol/L^-And (3) detecting, and comparing the detection result with a detection result obtained by modifying a glassy carbon electrode (Au @ AgNPs/graphene/GCE) with graphene/gold @ silver nanoparticles.

The detection result shows that the modification of the nanogold and the graphene on the surface of the electrode is beneficial to the deposition of the silver on the modified electrodeThe surface of the electrode is more beneficial to I^-And the silver-ion-exchange membrane reacts with Ag on the surface of the electrode, so that the difference of stripping voltammetric signals of the silver on the surface of the electrode before and after detection is greatly increased. Therefore, the difference value of electrochemical signals obtained on the Au @ AgNPs/graphene/GCE before and after etching is far larger than the difference value of stripping volt-ampere signals of silver before and after detection obtained on AgNPs/GCE, AgNPs/graphene/GCE and Au @ AgNPs/GCE electrodes. Due to the modification of the graphene, the conductivity of the electrode can be increased, and the surface area of the electrode can be greatly increased. After the nanogold is modified on the surface of the electrode, the specific surface area of the electrode can be further increased, and due to the nanogold induced silver deposition effect, a large amount of silver can be reduced to the surface of the nanogold in the presence of AA, so that Au @ AgNPs/graphene GCE is obtained, and the electrode is more beneficial to I^-And etching the silver reaction, thereby showing that the detection sensitivity of the method can be obviously improved by adopting Au @ AgNPs/graphene/GCE as a working electrode.

Through the above tests, it is proved that the method of the present invention can be applied to I^-The detection is simple to operate, the sensitivity is high, the detection limit is as low as 4.6nmol/L, and the method does not need a complex instrument and can realize the detection of I in an actual sample^-High sensitivity detection.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. A preparation method of a graphene/gold @ silver nanoparticle modified electrode for iodine ion detection is characterized by comprising the following steps:

the electrode is a glassy carbon electrode, and the dosage of the modification solution is 0.71 muL/mm²Equivalently, taking 5 muL of modification solution from an electrode with the diameter of 3 mm;

step (3), placing the graphene modified electrode in 5mmol/L HAuCl₄In the solution, applying a potential of-0.2V to reduce for 60s to obtain a graphene/nano gold modified electrode;

2. The method for preparing the graphene/gold @ silver nanoparticle modified electrode for iodine ion detection according to claim 1, wherein the glassy carbon electrode is polished on a wet chamois leather by using 0.5 μm and 0.05 μm of aluminum oxide powder in sequence, polished to a mirror surface, then ultrasonically cleaned for each L min by using ultrapure water, absolute ethyl alcohol and ultrapure water in sequence, then the glassy carbon electrode is placed in a 1mmol/L potassium ferricyanide solution, cyclic voltammetry scanning is performed within a potential range of-0.2V-0.6V, and when the potential difference of an oxidation reduction peak of potassium ferricyanide is below 80mV, the surface of the glassy carbon electrode is treated cleanly.

3. The use of the graphene/gold @ silver nanoparticle modified electrode for iodide ion detection as defined in claim 1 or 2 in the detection of iodide ions.

4. The application of the graphene/gold @ silver nanoparticle modified electrode for iodine ion detection in the detection of iodine ions according to claim 3 is characterized by comprising the following steps:

and (2) inserting a graphene/gold @ silver nanoparticle modified electrode serving as a working electrode into the reaction solution obtained in the step (1), reacting for 20 minutes in a dark place at 37 ℃, washing the working electrode with ultrapure water, placing the washed working electrode into a 1mol/L KCl aqueous solution for linear voltammetry scanning determination, wherein the scanning range of the linear voltammetry scanning is-0.2-0.4V, the scanning rate is 100mV/s, and quantifying iodide ions by adopting a standard curve method according to the detected intensity of an oxidation signal of silver.