CN111562294B - Nanocomposite electrochemical sensor, construction method and application of nanocomposite electrochemical sensor in nitrite ion and iodide ion detection - Google Patents
Nanocomposite electrochemical sensor, construction method and application of nanocomposite electrochemical sensor in nitrite ion and iodide ion detection Download PDFInfo
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Abstract
The invention is based on a carboxylated graphene (COOH-G) nano material, and noble metals of gold Au and silver Ag are loaded on the material, so as to synthesize a nano composite material, namely, a carboxylated graphene loaded gold and silver (COOH-G/Au @ Ag), with high sensitivity and high conductivity. The material modified glassy carbon electrode is constructed into a novel electrochemical sensor for detecting various ions. The response to nitrite ions and iodide ions is accurate, the two ions can be responded simultaneously, and detection results are not interfered with each other. The sensor has a detection limit of 0.165 mu M for nitrite ions, a detection range of 0.5 mu M-31.983 mM, and a detection limit of 0.833 mu M for iodide ions, a detection range of 35 mu M-1-0.37 mM. The sensor is simple to operate, quick in response, low in cost, wide in linear range and good in application prospect.
Description
Technical Field
The invention relates to a nanocomposite electrochemical sensor, a construction method and application thereof in nitrite ion and iodide ion detection, and belongs to the technical field of electrochemistry.
Background
Sensors are devices or arrangements for sensing a predetermined quantity of measurement and for converting it into a usable output signal in accordance with a certain law, usually consisting of a sensing element and a conversion element [1] . Recent developments in sensors have moved toward new sensors, environmentally friendly chemical sensors, industrial process control and automotive sensors, which are urgently needed for biomedical research [2] 。
An electrochemical sensor is a common sensor, and materials with photoelectric and catalytic functions are directionally covered on an electrode of the sensor mainly through covalent bonding, adsorption, polymerization and other modes in physics or chemistry, so that the electrochemical sensor has a new function, and the process is also an electrode modification process, and the obtained new electrode is called a modified electrode [3] . The electrochemical sensor is a detection device with low cost and quick detection. The emergence of chemically modified electrodes has driven the development of electrochemistry, which is capable of accelerating the electron transfer rate [4] 。
The principle of detection of the electrochemical sensor is to establish a three-electrode system, which consists of a working electrode WE, a reference electrode CE and an auxiliary electrode RE. Electrochemical sensors can be classified into ion sensors, gas sensors and biosensors according to the substances detected by the electrochemical sensors [5] . The sensor displays its material characteristics in a graphical and data manner, which is an important and well-utilized low-cost and low-energy analysis means. The technology can be widely applied to modern environmental analysis, food analysis and life molecules [6] Can solve many common problems in life.
Carbon element is a common element in life, and has applications in various aspects such as textile clothing, tools, production and the like, and has three electronic hybridization modes sp and sp 2 、sp 3 Form a colorful carbon material world comprising graphite, diamond and C60-fullerene [7] Carbon nanotube [8] And graphene [9] 。
Graphene can be used in many research areas, although from thereThe graphene is found to be existed for years so far, and still shows strong superiority and huge scientific value. Pure graphene has many limitations in application because of its surface inertness and unstable dispersion, and in order to better utilize the advantages of graphene, graphene can be functionalized to expand its application field. At present, the functionalization of graphene has two modes: covalent bond functionalization and non-covalent bond functionalization [10] . The carboxylated graphene (COOH-G) is functionalized graphene, the layered surface has rich carboxyl functional groups, the functional groups have sensibility and can improve the activity of the original material, and the research prospect of the COOH-G is more prospective.
Noble metals of gold, silver, palladium and platinum ] And the Noble Metal Nano Particles (NMNPs) enter the microcosmic state from the macroscopic state along with the popularization of the nanotechnology, and show a plurality of properties with research significance by combining the macroscopic physical and chemical properties of the nano particles, and compared with the noble metal in the common state, the specific surface area of the nano particles is larger, the surface energy is increased, the number of surface atoms is increased, so that the nano particles have strong catalytic performance and stronger conductivity [11~14] 。
Nitrite is widely used in industrial and agricultural production. It is ubiquitous in food, drinking water, biology and the environment. However, nitrite is a toxic substance and causes considerable harm to human body. Nitrite ion (NO) 2 - ) Due to their irreplaceable role in numerous food products, they play an important role mainly in preventing food spoilage and bacterial growth. But excessive nitrite ions cause bluebaby syndrome [15] Stomach cancer [16] Spontaneous abortion [17] The limit value of nitrite in the environment is regulated in many countries, and 21.7 mmol L is regulated in the United states -1 The world health organization specifies 3 ppm [18] The EU stipulates that the daily intake is 0.06 mg kg -1[19] The maximum usage amount of nitrite in food specified by national standard of China is 0.15 mg kg -1[20]
Iodide ion (I) - ) Is an essential element for human body, and canStabilizing thyroid function, nerve activity and control formula, wherein the daily iodine ion intake of human body is 100-150 μ g, and the beyond range is harmful to human body. NO (nitric oxide) 2 - And I - Is easy to cause thyroid gland injury [21~22] . Because various waste waters produce a large amount of NO 2 - And I - Polluting the source of drinking water, posing a non-negligible threat to the physical health of residents, the common one is: soluble ions, nitrites and iodide ions can form various cation-dissolving salts. Therefore, sensitive and efficient detection and monitoring of nitrite and iodide ions will be the most important tool. In recent years, researchers have developed a number of methods for detecting nitrite. Electrochemical analysis is popular among researchers and consumers due to its advantages of simplicity, rapidness, high sensitivity, etc.
[1] GB 7665-87 National Standard of the People's Republic of China National Standards of the peoples's Republic of China.
[2] Shenxiping, electrochemical sensing technology and nano material application research [ J ] modern salt chemical industry, 2018,5: 91-92.
[3] Electrochemical biosensing [ J ] based on graphene modified electrodes, chemical bulletin, 2014 (72): 319-322.
[4] Dr. M. U. Anu Prathap,Dr. Balwinder Kaur,Dr. Rajendra Srivastava. Electrochemical Sensor Platforms Based on Nanostructured Metal Oxides, and Zeolite‐Based Materials[J]. The Chemical Record, 2019,19(5): 883-907.
[5] The research on the application of the composite material of the Qigong, jiangfeng and the silver nano particles in the electrochemical sensor progresses [ J ] chemical novel materials, 2017,45 (9): 12-13.
[6] Liu Y J, Kristina Peters, Benjamin Mandlmeiera, et al. Macroporous indium tin oxide electrode layers as conducting substrates for immobilization of bulky electroactive guests[J]. Electrochimica Acta, 2014, 140(10): 108-115.
[8] Iijima S, Helical microtubules of graphitic carbon[J]. Nature, 1991, 354: 56-58.
[9] Novoselov K S, Geim A K, Morozov S V, et al. Electric field effect in atomically thin carbon films[J], Science, 2004, 306: 666-669. [9] Novoselov K S, Geim A K, Morozov S V, et al. Electric field effect in atomically thin carbon films[J], Science, 2004, 306: 666-669.
[10]Qin Xu,Sai-XiGu, Yue-e Zhou,Zhan jun Yang,Wei Wang,Xiaoya/polyaniline/gold nanoparticles nanocomposite for the direct electron transfer of glucose oxidase and glucose biosensing[J].Sensors & Actuators: B. Chemical ,2014(190): 562-569.
[11] Lee M, Kim D. Non-enzymatic carbohydrates detection based on Au modified MWCNT field-effect transistor[J]. Materials Letters, 2016, 169(15): 257-261.
[12] Tajabadi M T, Basirun W J, Lorestani F, et al. Nitrogen-doped graphene-silver nanodendrites for the non-enzymatic detection of hydrogen peroxide[J]. Electrochimica Acta, 2015, 151(1): 126-133.
[13] Jiang F X, Yue R R, Du Y K, et al. A one-pot ‘green’ synthesis of Pd-decorated PEDOT nanospheres for nonenzymatic hydrogen peroxide sensing[J]. Biosensors and Bioelectronics, 2013, 44(15): 127-131.
[14] Chang G, Shu H H, Huang Q W, et al. Synthesis of highly dispersed Pt nanoclusters anchored graphene composites and their application for non-enzymatic glucose sensing[J]. Electrochimica Act, 2015, 157(1): 149-157.
[15]Xuemei Li,Yongshan Ma,Yifei Yang,Junsen Wu,Tianyi Jiang,Huixue Ren,Ruimin Mu,Xiangfeng Jia. Recyclable nitrite ion sensing nanocomposites based on a magnetic-emissive core–shell structure: Characterization and performance[J]. Inorganica Chimica Acta,2018:469.
[16] Jakszyn P, Gonzalez C A. World J. Gastroenterol. , 2006, 12(27): 4296-4303.
[17] Hairy swallow, bayu, handong snow, zhao Ice, nitrite electrochemical sensor research progress [ J ] analytical chemistry review and progress 2018, (46): 147-156.
[18] Adarsh N, Shanmugasundaram M, Ramaiah D. Anal. Chem. , 2013, 85(21) : 10008-10012.
[19] özdestanö, üren A. J. Agr. Food Chem. , 2010, 58(9) : 5235-5240.
[20] GB 2760-2014 , National Food Safety Standard Standards of Using Food Additives. National Standards of the People 's Republic of China.
Disclosure of Invention
The purpose of the invention is: provides an electrochemical sensor for detecting nitrite ion and iodide ion mixed solution, which takes COOH-G/Au @ Ag nano composite material as a detection electrode and has the capability of detecting NO 2 - And I - The method has the advantages of simultaneous detection and no mutual interference, and also has the advantages of wide detection range and good stability.
The technical scheme is as follows:
a nano-composite electrochemical sensor is an electrode loaded with a COOH-G/Au @ Ag material.
In one embodiment, the COOH-G/au @ ag material is a nanoparticle in which gold and silver are sequentially coated on the surface of carboxylated graphene.
The preparation method of the nanocomposite electrochemical sensor comprises the following steps:
polishing the surface of the glassy carbon electrode;
preparing a suspension of the COOH-G/Au @ Ag material, adding the suspension to the surface of the carbon breaking electrode, and drying to obtain the carbon breaking electrode.
In one embodiment, the suspension of the COOH-G/Au @ Ag material has a concentration of 3 mg mL -1 。
The application of the nanocomposite electrochemical sensor in the detection of a solution containing nitrite ions and iodide ions is provided.
In one embodiment, the detection is cyclic voltammetry.
In one embodiment, the solution contains 1mM iodide ion and 1mM nitrite ion.
In one embodiment, the solution has a pH of 7.6.
Advantageous effects
The COOH-G/Au @ Ag nano composite material is synthesized, the appearance of the composite material is characterized, and the composite material has excellent conductivity. The nitrite ion (NO) is constructed by using the composite material 2 - ) And iodide ion (I) - ) The diionic electrochemical sensor of (1). The sensor is measured by cyclic voltammetry and other analysis means, and is found to be capable of measuring NO 2 - And I - While detecting and not interfering with each other. Analysis of electrochemical sensor for nitrite ion (NO) by Current time I-t 2 - ) And iodide ion (I) - ) The detection limit and the linear detection range of the sensor are wide, and the stability is good. The sensor constructed by COOH-G/Au @ Ag has the advantages of low cost, sensitive detection, rapid conduction and good application prospect.
Drawings
FIG. 1 is a flow chart for the preparation of a sensor.
FIG. 2 SEM and TEM of COOH-G/Au @ Ag under different magnification conditions
FIG. 3 impedance diagram of each material (bare electrode GCE, initial sample (graphene), intermediate sample (COOH-G/Au), final sample (COOH-G/Au @ Ag))
FIG. 4 cyclic voltammograms of different sweep rates COOH-G/Au @ Ag modified electrode (10, 30, 50, 80, 100, 150, 200, 250, 300 Vs) -1 ）
FIG. 5 is a CVs graph comparing the response of three electrodes modified with different materials (COOH-G, COOH-G/Au @ Ag) to 1mM iodine ion and nitrite ion
FIG. 6 LSV diagram of COOH-G/Au @ Ag modified electrode under various conditions
FIG. 7 LSV diagram of COOH-G @ Au @ Ag modified electrode in buffer solution (a-m control iodide ion content constant 0.4 mM, gradually increase nitrite ion content 0.0 mM,0.01 mM,0.03 mM,0.08 mM,0.18 mM,0.28 mM,0.53 mM,0.78mM,1.28 mM,1.78 mM,2.58 mM,3.38 mM,4.38 mM,6.38 mM)
FIG. 8 LSV diagram of COOH-G/Au @ Ag modified electrode in buffer solution (a-n control nitrite ion content constant 0.4 mM, content of gradually increasing iodide ion 0.0 mM,0.01 mM,0.03 mM,0.08 mM,0.18 mM,0.28 mM,0.53 mM,0.78mM,1.28 mM,1.78 mM,2.58 mM,3.38 mM,4.38 mM,6.38 mM)
FIG. 9 two ions interact with each other to influence LSV
FIG. 10 It map of nitrous acid
FIG. 11 COOH-G/Au @ Ag modified electrode pair NO 2- Corresponding linear regression curve (0.8V)
FIG. 12 it diagram of iodide ion
FIG. 13 COOH-G/Au @ Ag modified electrode pair I - Corresponding linear regression curve (0.5V)
Detailed Description
Based on the structural characteristics of carboxylated graphene (COOH-G), the novel nano composite material carboxylated graphene loaded with gold and silver (COOH-G @ Au- @ Ag) is synthesized by loading the gold Au and silver Ag on the surface of the carboxylated graphene (COOH-G) so as to improve the conductivity of the material, and the electrochemical sensor constructed by the novel nano composite material carboxylated graphene loaded with gold and silver (COOH-G @ Au- @ Ag) can well detect various ions, is low in cost and high in speed, and can simultaneously respond to nitrite ions and iodide ions.
Reagent and apparatus
TABLE 1 reagents
TABLE 2 Instrument
Arrangement of the Primary reagents
(1) Preparation of grinding electrode solution
0.1 mol potassium chloride +1 mmol potassium hexacyanoferrate
TABLE 3 preparation of electrode grinding solution
(2) Preparation of PBS buffer solution
Potassium dihydrogen phosphate and sodium hydroxide under different pH values in the corresponding table are respectively weighed, and the volume is determined by a 100mL volumetric flask
TABLE 4 preparation of PBS solution
③ 5.0 mmol L -1 K 3 Fe(CN) 6 /K 4 Fe(CN) 6 Impedance solution
TABLE 5 preparation of the resist solution
④ NaNO 2 Sodium nitrite
TABLE 6 NaNO concentrations 2 Preparation of sodium nitrite
The first three low concentration solutions are diluted with high concentration
(5) KI potassium iodide
TABLE 7 configuration of different concentrations of KI Potassium iodide
Electrode activation
(1) Electrode pretreatment
The method is to firstly wet a chamois leather dispersed with 200-300 nm alumina polishing powder with deionized water, then wash the glassy carbon electrode with the deionized water, and polish the chamois leather for 3 min according to the smoothness until the surface is smooth. Ethanol: and ultrasonically cleaning the deionized water for 5 min according to the following steps of 1.
(2) Electrode activation and detection
After pretreatment, the electrode is washed by deionized water again, a three-electrode system is established, cyclic voltammetry scanning is carried out in an electrode grinding solution, and the potential difference between an oxidation peak and a reduction peak is calculated and is smaller than 80 mV.
Electrode modification
3 mg of COOH-G/Au @ Ag material was weighed out and prepared into 3 mg mL -1 The suspension of (2) is sonicated with a sonicator until homogeneous. Transfer 5 μ L of the material drop to the surface of the carbon-breaking electrode with a micro-syringe and dry at room temperature. And drying for 5 min with an infrared oven when drying is difficult.
The COOH-G/Au @ Ag nano composite is prepared by a two-step continuous reduction method. Firstly, 6 mg of carboxylated graphene (COOH-G) is weighed by an analytical balance and placed in a clean beaker, 50 mL of distilled water is weighed and poured into the beaker, then the beaker is sealed by a preservative film, and the beaker is ultrasonically dispersed for 6 hours. Then transferring the uniformly peeled carboxylated graphene suspension into a 100mL three-well flask, setting the oil bath temperature at 100 ℃, and adding 200 mu L of 2.94 multiplied by 10 -2 M chloroauric acid (HAuCl) 4 ) Thereafter, 0.53 mL of 3.88X 10 was added -2 And (3) after the solution becomes red, reacting for 30 min, turning off heating, and continuing stirring to naturally cool the reaction mixture to room temperature. The resulting sample was centrifuged and redissolved in 30 mL of distilled water, 200. Mu.L of 1.93X 10 was added -2 M silver nitrate and 0.3 mL of 0.1M Ascorbic Acid (AA) are added, the ice bath temperature is set to 4 ℃, after 2 hours, the mixture is kept stand and stirred for 2 hours at room temperature until the solution becomes dark brown, centrifugal separation is carried out after the reaction is finished, and vacuum drying is carried out to obtain the COOH-G/Au @ Ag nano composite material.
Electron microscopy of COOH-G/Au @ Ag
The surface gully-shaped structure of the COOH-G material is a good carrier structure and is easy to adsorb noble metal nano particles, FIG. 2 is an electron microscope photograph, four parts of ABCD are SEM and TEM images under different multiplying powers respectively, part A can show that metal ions are represented as spheres, part B can show that the metal particles in the sphere shape are loaded on a flaky graphene material, part C can obviously show that compact and regular metal nano spheres are loaded on flaky folds, and part D can show an Au @ Ag core-shell nano structure. These metal particles can greatly improve the conductivity of the graphene material.
Impedance analysis of COOH-G/Au @ Ag
The conductivity of the material is analyzed by using an interface analysis technique of electrochemical alternating current impedance analysis (EIS), wherein the semi-circle in the graph of FIG. 3 represents the charge transfer process of a high-frequency region, the straight line represents the diffusion control process of a low-frequency region, and the smaller the radius of the semi-circle represents the smaller the impedance of the material, the better the conductivity. As shown in FIG. 3, nyquist plots (bare electrode GCE, initial (carboxylated graphene COOH-G), intermediate (carboxylated graphene loaded with gold COOH-G/Au), and final (COOH-G/Au @ Ag) for the four electrodes were obtained in the laboratory in the presence of an impedance solution, and it was found from the plots that the impedance of the bare electrode was the lowest and the resistance was 111. Omega. Cm 2 Followed by the final sample COOH-G/Au @ Ag, resistance at 550. Omega. Cm 2 Then intermediate sample COOH-G/Au with resistance of 812 omega cm 2 The maximum resistance of the originally pure carboxylated graphene material is 1220 omega cm 2 . Shows the high conductivity of the prepared material COOH-G/Au @ Ag.
Analysis by sweeping velocity
To optimize the electrocatalytic performance of the sensor, we investigated sweep rates from different sweep rates (0.01, 0.03, 0.05, 0.08, 0.1, 0.15, 0.20, 0.25, 0.3 vs) as shown in FIG. 4 -1 ) Influence on cyclic voltammetry curve of COOH-G @ Au @ Ag modified electrode. It can be seen from the figure that the oxidation-reduction peak in the figure is more distinct at higher sweep rates, and shows diffusion-controlled electrochemical processes at low sweep rates and surface-controlled electrochemical processes at high sweep rates. Under different sweep rates, different electron transfer processes are the processes that reaction substances are not in time to be transmitted and are accumulated on the surface of the electrode, so that the catalytic oxidation of the modified electrode on ions is a double-diffusion control process.
Response of COOH-G/Au @ Ag to nitrite ions and iodide ions
Electrochemical behavior of COOH-G/Au @ Ag nanocomposite
We determined various ions (sodium nitrite (NaNO) by Cyclic Voltammetry (CVs) on electrodes modified with COOH-G/Au @ Ag 2 ) Ascorbic Acid (AA), dopamine (DA) sodium hydroxide (NaOH) hydrogen peroxide (H) 2 O 2 ) Uric Acid (UA) potassium iodide (KI) Glucose (Glucose)) equivalent concentration response scenario, wherein for KI and NaNO 2 The response of (2) is optimal. Similarly, we detected an optimum pH of 7.6 at pH 7.0-8.0, under which we performed specific electrochemical analyses for COOH-G/Au @ Ag.
FIG. 5 shows the three materials vs. nitrite ion (NO) 2 - ) And iodide ion (I) - ) CV diagram of response (COOH-G (original), COOH-G/Au @ Ag). In the experiment, the responses to 1mM iodide ion and nitrite ion are compared, and COOH-G can not detect NO 2 - And I - The mesogen COOH-G/Au is inductive but not as responsive as COOH-G/Au @ Ag.
FIG. 6 is a linear cyclic voltammogram (LSV) of the COOH-G/Au @ Ag modified electrode under various conditions. 1mM nitrite ion and iodide ion were added to PBS, respectively, for comparison. Conclusion as shown in table 8, it is proved that the material is sensitive to both nitrite ions and iodide ions, and can respond to both ions simultaneously without mutual influence.
Table 8 comparison of the position of peaks in LSV plots with addition of different ions
Different concentrations of NO 2 - And I - Influence on the Condition of modified electrode response
(1) Influence of nitrite ion concentration on detection of iodide ions with same concentration
Control of I in PBS solution - In a concentration of 0.4 mM, gradually increasing NO 2 - In the following order, the content of (A) is gradually increased to 0.0 mM,0.01 mM,0.03 mM,0.08 mM,0.18 mM,0.28 mM,0.53 mM,0.78mM,1.28 mM,1.78 mM,2.58 mM,3.38 mM,4.38 mM,6.38 mM. As shown, increase in NO 2 - Does not affect the pair I - Detection of (2)
(2) Influence of iodide ion concentration on nitrite ion detection
FIG. 8 is a LSV diagram of a COOH-G @ Au @ Ag modified electrode in PBS with the contents of NO 2-0.4 mM being controlled to be constant and the contents of I-being gradually increased in the order of 0.0 mM,0.01 mM,0.03 mM,0.08 mM,0.18 mM,0.28 mM,0.53 mM,0.78mM,1.28 mM,1.78 mM,2.58 mM,3.38 mM,4.38 mM,6.38 mM. As shown in the figure, increasing the concentration of iodide ions did not affect the detection of nitrite ions.
(3) FIG. 9 simultaneous addition of two ions (NO) 2 - ,I - ) While varying the concentrations of the two ions, the concentrations of a-j are 0.0 mM,0.01 mM,0.03 mM,0.08 mM,0.18 mM,0.28 mM,0.53 mM,0.78mM,1.28 mM,1.78 mM,2.58 mM,3.58 mM,5.58 mM, respectively. It can be found from the graph that the responses of the two ions do not disappear due to the presence of the other ion, and the detection of the two ions does not affect each other.
2. COOH-G/Au @ Ag modified electrode pair NO 2 - And I - Ampere current response
1. Amperometric response of nitrite ions
FIG. 11 is an I-t spectrum of nitrite ion, which is obtained by adding NaNO at different concentrations to PBS under the potential condition of 0.8V 2 Respectively is as follows: 0.005,0.01,0.05,0.1,0.5,1,2,3,4 mM. From FIG. 12, it can be obtained that the modified electrode is for NO 2 - The detection limit is 0.167 mu M, the linear range of detection is 0.5 mu M-31.983 mM, and the electrochemical sensor constructed by the material has high sensitivity and wider detection range.
2. Amperometric response of iodide ion:
FIG. 12 is an I-t spectrum of iodide ion obtained by adding KI at different concentrations to PBS under a potential of 0.5V, wherein the concentrations are as follows: 2.5 mu.M, 5. Mu.M, 0.01 mM,0.05 mM,0.1 mM,0.5 mM, 1mM, 2 mM,3 mM,4 mM. From FIG. 13, it can be seen that the detection limit of the modified electrode for I is 0.833. Mu.M, and the linear range is 35. Mu.M-0.37 mM. Therefore, the electrochemical sensor constructed by the material has high sensitivity and wide detection range.
Claims (2)
1. The application of the nano-composite electrochemical sensor in the detection of a solution containing nitrite ions and iodide ions is characterized in that the nano-composite electrochemical sensor is an electrode loaded with a COOH-G/Au @ Ag material, the COOH-G/Au @ Ag material is nano-particles coated with gold and silver on the surface of carboxylated graphene in sequence, and the preparation method of the COOH-G/Au @ Ag material comprises the following steps: weighing 6 mg of carboxylated graphene, putting the weighed carboxylated graphene into a beaker, weighing 50 mL of distilled water, pouring the distilled water into the beaker, ultrasonically dispersing the weighed carboxylated graphene for 6 hours, transferring the uniformly peeled carboxylated graphene suspension into the flask, setting the oil bath temperature to be 100 ℃, and adding 200 mu L of 2.94 multiplied by 10 -2 M Chloroauric acid was added to the mixture in an amount of 0.53 mL, 3.88X 10 -2 M sodium citrate solution is added until the solution turns red, after reaction for 30 min, heating is closed, and stirring is continued to naturally cool the reaction mixture to room temperature; the resulting sample was centrifuged and redissolved in 30 mL of distilled water, 200. Mu.L of 1.93X 10 was added -2 Setting the ice bath temperature to 4 ℃ for M silver nitrate and 0.3 mL 0.1M ascorbic acid, standing and stirring at room temperature for 2 hours until the solution becomes dark brown, centrifugally separating after the reaction is finished, and drying in vacuum to obtain the required COOH-G/Au @ Ag nano composite material;
the preparation method of the electrode loaded with the COOH-G/Au @ Ag material comprises the following steps: polishing the surface of the glassy carbon electrode; preparing a suspension of a COOH-G/Au @ Ag material, adding the suspension to the surface of the carbon breaking electrode, and drying to obtain the carbon breaking electrode;
the detection is cyclic voltammetry;
the solution contains 1mM of iodide ions and 1mM of nitrite ions;
the pH of the solution was 7.6.
2. Use according to claim 1, characterized in that the suspension of the COOH-G/Au @ Ag material has a concentration of 3 mg-mL -1 。
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| CN103194061B (en) * | 2013-04-11 | 2015-05-13 | 北京化工大学 | Silver nanosheet-graphene composite material as well as preparation method and application thereof |
| CN207908426U (en) * | 2018-02-05 | 2018-09-25 | 孙大明 | A kind of Electrochemical Modification electrode of quick detection nitrite |
| CN109187678A (en) * | 2018-07-11 | 2019-01-11 | 杭州电子科技大学 | Utilize the nitrite detection device of nanogold graphene modified electrochemical method |
| CN110441358B (en) * | 2019-07-10 | 2021-08-13 | 云南大学 | Method for detecting iodide ions based on graphene/gold @ silver nanoparticle modified electrode |
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