CN111474221B - Electrochemical sensor based on gold nanocage/fluorinated graphene and application - Google Patents
Electrochemical sensor based on gold nanocage/fluorinated graphene and application Download PDFInfo
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Abstract
The invention relates to an electrochemical sensor based on a gold nanocage/fluorinated graphene and application thereof, and belongs to the technical field of novel functional materials and electrochemical sensing detection. The electrochemical sensor can realize high-sensitivity detection of selenium, the detection limit is 0.27 mug/L, and the linear range is 2-5000 mug/L. The electrochemical sensor combines the excellent properties of the gold nanocages and the fluorinated graphene and the synergistic effect of the gold nanocages and the fluorinated graphene, has high sensitivity, low detection limit, wide linear range, good selectivity, excellent repeatability, stability and the like, and can be applied to detection of selenium in actual food samples and environments.
Description
Technical Field
The invention belongs to the technical field of novel functional materials and electrochemical sensing detection. In particular to a gold nanocage/fluorinated graphene electrochemical sensor, a preparation method and a selenium detection method.
Background
With the rapid development of modern society, people's demand for nutrition is increasing day by day. Agricultural food rich in selenium attracts great attention of people because selenium is an essential micronutrient in human nutrition, has the effects of resisting oxidation, aging, cancer and the like, can remove free radicals, improves the immunity of human bodies, protects heart and cerebral vessels and the like. While selenium is often taken from food and the environment as the main way to balance selenium levels in humans, few organs can store selenium for long periods of time. It is well known that deficiencies in selenium (< 40 μ g/d) or excessive intake of selenium (> 400 μ g/d) can have serious health consequences for humans. On the one hand, selenium deficiency can lead to a high incidence of various diseases, such as keshan disease, metabolic syndrome, parkinson disease, cardiovascular disease, and the like. On the other hand, excessive selenium may cause selenium poisoning, including myocardial infarction, neurological disorders, renal failure, etc., and may lead to death in severe cases.
With increasing concerns about nutrition and health, the healthy intake of selenium becomes more and more important, and there is therefore an urgent need to develop a rapid detection method for the determination of selenium in foods and in the environment. At present, the traditional methods for detecting selenium mainly include inductively coupled plasma mass spectrometry, gas chromatography, atomic absorption spectrometry and atomic fluorescence spectrometry. Problems and deficiencies of the prior art; although the methods mentioned above have good selectivity and high sensitivity, these methods require expensive equipment, large volume of equipment, are not portable, and require long time for preparing samples, complicated equipment operation, and require professional detection. The electrochemical stripping voltammetry has the advantages of high sensitivity, simple operation, low cost, low detection limit, quick response and the like, can overcome the problems encountered by the traditional technology, and is a promising method for detecting trace selenium. Among various electrochemical stripping voltammetry methods, the anodic stripping voltammetry method has higher sensitivity and is more suitable for detecting trace selenium.
The key of the square wave anodic stripping voltammetry lies in the preparation of electrode materials, and the nano materials with unique performance can improve the performance of the electrochemical sensor.
Disclosure of Invention
One of the purposes of the invention is to provide an electrochemical sensor based on gold nanocages/fluorinated graphene.
The invention also aims to provide the application of the electrochemical sensor in selenium detection.
In order to achieve the purpose, the invention adopts the following technical scheme:
the gold nanocage/fluorinated graphene composite material comprises a nanoscale gold nanocage and fluorinated graphene nanosheets, wherein: the gold nanocages are in a three-dimensional cage-shaped hollow porous shape, the fluorinated graphene nanosheets are in a folded and layered form, and the gold nanocages are uniformly attached to the fluorinated graphene nanosheets.
According to the scheme, the particle size of the gold nanocages is 30-60nm.
The electrochemical sensor based on the gold nanocage/fluorinated graphene comprises an electrode substrate and a gold nanocage/fluorinated graphene composite material loaded on the electrode substrate.
According to the scheme, the electrode substrate is a glassy carbon electrode.
The preparation method of the electrochemical sensor based on the gold nano cage/fluorinated graphene comprises the following steps: pretreating the electrode substrate; and (3) dropwise coating the gold nanocage/fluorinated graphene composite material solution on the surface of the pretreated electrode substrate, naturally drying, and repeating for multiple times to obtain the electrochemical sensor based on the gold nanocage/fluorinated graphene.
According to the scheme, the electrode substrate is a glassy carbon electrode, and the pretreatment comprises the following steps: polishing the glassy carbon electrode, then placing the electrode in a potassium ferricyanide solution for cyclic voltammetry test to enable the redox peak potential difference of a cyclic voltammetry curve to be less than 70mV, finally performing ultrasonic cleaning on the glassy carbon electrode by using ultrapure water and absolute ethyl alcohol, and drying the glassy carbon electrode by using nitrogen.
The preparation method of the gold nanocage/fluorinated graphene composite material comprises the following steps:
(1) Preparing a gold nano cage, namely mixing precursor chloroauric acid and hexamethylenetetramine, then sequentially adding a polyvinylpyrrolidone protective agent, a silver nitrate crystal face regulating agent and an ascorbic acid reducing agent, stirring, and standing at room temperature for reaction to obtain a solution of the gold nano cage;
(2) Fluorination ofPreparing graphene, namely placing the graphene in a tube furnace, removing air and impurities, and then introducing F 2 Carrying out fluorination reaction to prepare fluorinated graphene;
(3) Preparing a gold nano cage/fluorinated graphene, dispersing the fluorinated graphene in an ethanol-Nafion solution, and performing ultrasonic dispersion to obtain a fluorinated graphene dispersion solution; and (2) adding the gold nanocage solution obtained in the step (1) into the solution, and performing ultrasonic treatment to obtain the gold nanocage/fluorinated graphene composite material.
According to the scheme, the reaction time is 22-26h when the mixture is kept stand at room temperature.
According to the scheme, the molar ratio of the chloroauric acid to the hexamethylenetetramine is as follows: 1:37-1:42.
According to the scheme, the molar ratio of the chloroauric acid to the polyvinylpyrrolidone protective agent is 1.
The molar ratio of the chloroauric acid to the silver nitrate crystal face regulating agent is as follows: 1, 0.40-1, and 0.50, wherein the molar ratio of the chloroauric acid to the ascorbic acid reducing agent is: 1:1.60-1:1.80.
According to the scheme, the step (2) is that graphene is placed in a reactor, then the reactor is placed in a tube furnace, and N is introduced 2 Removing air and impurities in the reactor, and then introducing F 2 Carrying out fluorination reaction at 165-185 ℃ for 1-2 hours in the atmosphere of F 2 /N 2 (1.
According to the scheme, the mass fraction of Nafion in the ethanol-Nafion solution is 0.2-0.5wt.%, and the ultrasonic dispersion time is 15-25min.
According to the scheme, the volume ratio of the fluorinated graphene dispersion liquid to the gold nanocage solution is 3.
The method for detecting selenium by using the gold nanocage/fluorinated graphene electrochemical sensor comprises the following analysis steps: the electrochemical sensor based on the gold nanocage/fluorinated graphene, namely a modified electrode, is used as a working electrode, a silver/silver chloride electrode is used as a counter electrode, a platinum column electrode is used as an auxiliary electrode, scanning is carried out by adopting a square wave anodic stripping voltammetry method based on a three-electrode system, the deposition voltage is-0.1V-0.4V, the deposition time is 180-300s, the square wave anodic stripping voltammetry peak current change is recorded, and the selenium content is calculated according to a linear relation curve of the square wave anodic stripping voltammetry peak current and the selenium concentration.
According to the scheme, the scanning window is 0.7V-1.3V.
According to the scheme, the electrolyte solution used in the three-electrode system is a 0.1-0.5M sulfuric acid solution.
According to the scheme, in the linear relation curve of the peak current and the selenium concentration, the concentration of the selenium standard solution is 1-6000 mu g/L.
Compared with the prior art, the invention has the beneficial effects that:
the gold nanocage/fluorinated graphene composite material provided by the invention has excellent performances such as large specific surface area, good catalytic activity, strong adsorption capacity and the like, wherein the fluorinated graphene in the gold nanocage/fluorinated graphene has the characteristics of high electron transmission rate, large specific surface area and easiness in modification, and the negative charge of the fluorinated graphene is enhanced due to introduction of a C-F bond in fluorination, so that the adsorption capacity on cations is enhanced; the gold nanocages have good catalytic activity and good adsorption performance on heavy metal ions, and are uniformly dispersed on the fluorinated graphene, so that the specific surface area of the composite material is large, and the electron transfer rate is good.
(2) The electrochemical sensor prepared by the invention can be used for detecting selenium with high sensitivity, has the detection limit of 0.27 mug/L and the linear range of 2-5000 mug/L, has the advantages of green and environment-friendly materials, wide detection linear range, low detection limit and quick response performance, and can realize simple, efficient and high-sensitivity detection.
(3) The electrochemical sensor prepared by the invention can be applied to detection of selenium ions in actual water samples and agricultural products. Has great application potential and wide application prospect in the fields of environmental monitoring, food safety, life science and the like.
Drawings
FIG. 1 is an XRD pattern of (A) FGP, auNCs/FG; (B) XPS survey spectrum of FGP, auNCs/FG; high resolution XPS spectra of the elements in AuNCs/FG: c1s (C), F1s (D), au4F (E). The crystal structure of the composite was determined by XRD characterization. In fig. 1A, the FGP peaks at 14.54 °,29.08 ° and 41.06 ° correspond to the (001), (002) and (100) crystal plane diffraction peaks of FGP standard card (JCPDS 30-0476). The diffraction peaks of AuNCs/FG at 38.50, 44.67, 65.13, 78.35 and 85.78 degrees are consistent with those of (111), (200), (220), (311) and (222) crystal planes of AuNC standard card (JCPDS 04-0784). The XRD characterization result shows that the AuNCs/FG composite material is successfully prepared, and no other miscellaneous peak appears, which shows that the prepared AuNCs/FG has higher purity. The chemical composition and electronic structure of AuNCs/FG were studied by XPS in FIG. 1B. In FGP, we found that the peak for C1s was at 284.6eV, the peak for O1s was at 532.7eV, and the peak for F1 was at 688.7eV. In AuNCs/FG, au4f shows a new peak at 86.2eV, indicating that AuNC has been successfully loaded onto FGP. The XPS characterization results are consistent with the reported FGP and AuNCs results. FIGS. 1C-E are high resolution XPS spectra for C1s, F1s, and Au4F, respectively. From the C1s spectrum (FIG. 1C), it can be seen that the 6 fitted peaks are located at 292.1eV, 290.3eV, 287.9eV, 286.2eV, 285.2eV, and 284.6eV, respectively, corresponding to-CF 2 C-F, C = O, C-C and C = C. As is clear from the F1s spectrum (FIG. 1D), there are two different bond types, the C-F bond (689.0 eV) and the-CF 2 bond (690.1 eV). The Au4f spectrum (FIG. 1E) shows two peaks of 87.2eV and 83.7eV, respectively, corresponding to the Au4f5/2 and Au4f7/2 orbitals, respectively.
In summary, XRD and XPS characterization demonstrated that gold nanocage/graphene fluoride (AuNCs/FG) nanocomposites were successfully prepared.
FIG. 2 is a scanning electron micrograph of (A) FGP, (B) AuNCs, and (C) AuNCs/FG; (D) AuNCs/FG high resolution scanning electron microscopy images; (E) AuNCs/FG, (F) C, (G) F, (H) Au element map. The morphology of FGP, auNCs and AuNCs/FG was studied by field emission Scanning Electron Microscopy (SEM). In fig. 2A, FGP has a wrinkled, multilayered filamentous morphology. In FIG. 2B, auNCs were found to be uniformly distributed hollow polygonal cage-like morphologies with a particle size of about 50nm. Fig. 2C and 2D are low-magnification SEM images and high-magnification SEM images, respectively, of the AuNCs/FG nanocomposite material, and it can be clearly seen that the AuNCs are uniformly distributed on the FGP. By element mapping characterization, the distribution of AuNCs/FG was studied. The different colors represent C, F and Au, respectively (FIGS. 2F-H). As can be seen, C, F and Au are uniformly distributed in fig. 2E, which means that AuNC and FGP are successfully compounded and AuNCs/FG composite is successfully prepared.
FIG. 3 is a Transmission Electron Microscope (TEM) image of (A) AuNCs, (C) AuNCs/FG; (B) AuNCs, (D) high resolution transmission electron microscopy images of AuNCs/FG. The shapes of AuNCs and AuNCs/FG are further characterized by a transmission electron microscope and a high-resolution transmission electron microscope. The TEM characterization results are consistent with the SEM characterization results. It can be seen from fig. 3A that the AuNCs has better uniformity, and the corresponding high-resolution transmission electron microscope (fig. 3B) shows that the morphology thereof is a three-dimensional cage-shaped hollow porous morphology, and the particle size is about 50nm. TEM images of AuNCs/FG in fig. 3C show that FG nanoplatelets are in wrinkled and layered morphology, and that AuNCs are uniformly attached to FG. HRTEM characterization of the corresponding AuNCs/FG (fig. 3D) further showed that the AuNCs had been successfully loaded onto FG and that the hollow porous structure of the AuNCs remained intact.
FIG. 4 shows (A) three different sensors for the same concentration Se 4+ The square wave anodic stripping voltammetry response of (1), wherein AuNCs (a), FG (b), auNCs/FG (c); (B) AuNCs/FG at 20mL of 0.5M H 2 SO 4 Contains 0mg/L and 1mg/L Se 4+ The square wave anodic stripping voltammetry response of (1) is compared with the graph. The electrochemical behavior of three sensors (AuNCs, FG and AuNCs/FG) on selenium was characterized by square-wave anodic stripping voltammetry (FIG. 4A). SWASV comparison of the three sensors shows that the AuNCs/FG sensor pair Se 4+ The determination of (2) has the best catalytic performance, which also shows that the AuNCs and FG have better synergistic effect. Addition of Se 4+ The preceding and following SWASV pairs show that in the absence of selenium ions, no SWASV peak was present, whereas in the presence of 1.0mg/L selenium ions, a distinct SWASV peak was observed at 1.02V, indicating that the AuNCs/FG sensor had good sensitivity to selenium ions, as shown in fig. 4B.
FIG. 5 shows (A) detection of Se by AuNCs/FG sensor 4+ The square wave anodic stripping voltammetry response graph; (B) Detection of Se 4+ AuNCs/FG sensor at 20mL at 0.5M H 2 SO 4 Medium to different concentrations of Se 4+ (0.001 mg/L-6.0 mg/L) was subjected to square wave anodic stripping voltammetry (FIG. 5A), the deposition potential was-0.3V, the deposition time was 240s, and the detection limit was 0.27. Mu.g/L and the linear range was 2-5000. Mu.g/L from the corresponding linear curve (FIG. 5B).
Detailed Description
Example 1
Preparation of gold nanocage/fluorinated graphene composite material
(1) Preparation of gold nanocages 6mL of 0.05M hexamethylenetetramine and 6mL of 1.25mM chloroauric acid were mixed in a 50mL beaker. Then, 6mL of 0.50M polyvinylpyrrolidone, 0.57mg of silver nitrate and 2.35mg of ascorbic acid were added to the mixed solution in this order, and stirred for 60 seconds. And finally, standing the mixture at room temperature for 24 hours to obtain a solution of the gold nanocages.
(2) Preparing fluorinated graphene, namely putting 200mg of graphene into a reactor, and introducing N 2 Air and impurities were removed from the reactor. Then, F is introduced 2 Fluorination at 180 ℃ for 1 hour in an atmosphere of F 2 /N 2 (1, 3 v/v), finally degassing to remove unreacted gas, and cooling to obtain the fluorinated graphene.
(3) Preparing the gold nanocage/fluorinated graphene, namely dispersing 3mg of fluorinated graphene in 500 mu L of ethanol-Nafion solution (wherein in the ethanol-Nafion solution, the mass fraction of Nafion is 0.5 percent by weight percent), ultrasonically dispersing for 20min, and then adding 125 mu L of gold nanocage to ultrasonically disperse for 30min to obtain the gold nanocage/fluorinated graphene composite AuNCs/FG.
FIG. 1 is an XRD pattern of (A) FGP, auNCs/FG; (B) XPS survey of FGP, auNCs/FG; high resolution XPS spectra of the elements in AuNCs/FG: c1s (C), F1s (D), au4F (E). The crystal structure of the composite was determined by XRD characterization. In fig. 1A, the peaks of FGP at 14.54 °,29.08 ° and 41.06 ° correspond to the (001), (002) and (100) crystal plane diffraction peaks of FGP standard card (JCPDS 30-0476). AuNCs/FThe diffraction peaks of G at 38.50 °,44.67 °,65.13 °,78.35 ° and 85.78 ° coincide with the (111), (200), (220), (311) and (222) crystal plane diffraction peaks of AuNC standard card (JCPDS 04-0784). The XRD characterization result shows that the AuNCs/FG composite material is successfully prepared, and no other miscellaneous peak appears, which shows that the prepared AuNCs/FG has higher purity. The chemical composition and electronic structure of AuNCs/FG were studied by XPS in FIG. 1B. In FGP, we found that the peak for C1s was at 284.6eV, the peak for O1s was at 532.7eV, and the peak for F1 was at 688.7eV. In AuNCs/FG, au4f shows a new peak at 86.2eV, indicating that AuNC has been successfully loaded onto FGP. The XPS characterization results are consistent with the reported FGP and AuNCs results in the literature. FIGS. 1C-E are high resolution XPS spectra for C1s, F1s, and Au4F, respectively. From the C1s spectrum (FIG. 1C), it can be seen that the 6 fitting peaks are located at 292.1eV, 290.3eV, 287.9eV, 286.2eV, 285.2eV, and 284.6eV, respectively, corresponding to-CF 2 C-F, C = O, C-C and C = C. As is clear from the F1s spectrum (FIG. 1D), there are two different bond types, the C-F bond (689.0 eV) and the-CF 2 bond (690.1 eV). The Au4f spectrum (FIG. 1E) shows two peaks of 87.2eV and 83.7eV, respectively, corresponding to the Au4f5/2 and Au4f7/2 orbitals, respectively.
In summary, XRD and XPS characterization demonstrated that gold nanocage/graphene fluoride (AuNCs/FG) nanocomposites were successfully prepared.
FIG. 2 is a scanning electron micrograph of (A) FGP, (B) AuNCs, and (C) AuNCs/FG; (D) AuNCs/FG high resolution scanning electron microscopy images; (E) AuNCs/FG, (F) C, (G) F, (H) Au. The morphology of FGP, auNCs and AuNCs/FG was studied by field emission Scanning Electron Microscopy (SEM). In fig. 2A, FGP has a wrinkled, multilayered filamentous morphology. In FIG. 2B, auNCs were found to be uniformly distributed hollow polygonal cage-like morphologies with a particle size of about 50nm. Fig. 2C and 2D are low-magnification SEM images and high-magnification SEM images, respectively, of AuNCs/FG nanocomposites, and it can be clearly seen that AuNCs are uniformly distributed on FGP. By element mapping characterization, the distribution of AuNCs/FG was studied. The different colors represent C, F and Au, respectively (FIGS. 2F-H). As can be seen, C, F and Au are uniformly distributed in fig. 2E, which means that AuNC and FGP are successfully compounded and AuNCs/FG composite is successfully prepared.
FIG. 3 is a Transmission Electron Microscope (TEM) image of (A) AuNCs, (C) AuNCs/FG; (B) AuNCs, (D) high resolution transmission electron microscopy images of AuNCs/FG. The shapes of AuNCs and AuNCs/FG are further characterized by a transmission electron microscope and a high-resolution transmission electron microscope. The TEM characterization results are consistent with the SEM characterization results. As can be seen from FIG. 3A, auNCs have good uniformity, and the corresponding high-resolution transmission electron microscope (FIG. 3B) shows that the morphology of AuNCs is a three-dimensional cage-shaped hollow porous morphology with a particle size of about 50nm. TEM images of AuNCs/FG in fig. 3C show that FG nanoplatelets are in wrinkled and layered morphology, and that AuNCs are uniformly attached to FG. HRTEM characterization of the corresponding AuNCs/FG (fig. 3D) further showed that the AuNCs had been successfully loaded onto FG and that the hollow porous structure of the AuNCs remained intact.
Preparation method of gold nanocage/fluorinated graphene electrochemical sensor, namely gold nanocage/fluorinated graphene modified electrode
(1) Polishing the glassy carbon electrode by using 0.3 and 0.05 mu m-sized alumina slurry in sequence, then placing the electrode in a 5mmol/L potassium ferricyanide solution, scanning at a potential of-0.2-0.6V to ensure that the difference value of redox peak potentials is less than 70mV, finally performing ultrasonic cleaning on the glassy carbon electrode by using ultrapure water and absolute ethyl alcohol, and drying the glassy carbon electrode by using nitrogen;
(2) And (3) dropwise coating the gold nanocage/fluorinated graphene composite material on the surface of the polished glassy carbon electrode by using a liquid transfer gun, naturally drying, repeating the step three times, and dropwise coating 9 mu L in total to obtain the gold nanocage/fluorinated graphene-based electrochemical sensor.
Compared with a single gold nanocage electrochemical sensor or a single fluorinated graphene sensor, the obtained gold nanocage/fluorinated graphene electrochemical sensor has the advantages that the test performance is improved by 1.9 times and 1.7 times respectively. See fig. 4.
Detection of selenium
a, drawing a standard curve:
the determination was carried out using a three-electrode system in an electrochemical workstation, using the prepared gold nanocage/graphene fluoride modified electrode as a working electrode, a silver/silver chloride electrode as a counter electrode, a platinum column electrode as an auxiliary electrode, in a 0.5M sulfuric acid solution at a concentration of 20mL 0.5M H 2 SO 4 In the method, a square wave anodic stripping voltammetry test is carried out on a 0.001-6.0 mg/L selenium standard solution, the current change is recorded, the deposition voltage is-0.3V, the deposition time is 240s, as shown in figure 5A, a working curve is drawn according to the linear relation between the peak current of the square wave anodic stripping voltammetry and the concentration of selenium, as shown in figure 5B. The detection limit was 0.27. Mu.g/L from the corresponding linear curve (FIG. 5B), with a linear range of 2-5000. Mu.g/L. Compared with other sensor selenium detection performances reported in the prior art, the gold nanocage/fluorinated graphene electrochemical sensor has a wider linear range and a lower detection limit.
b, detection of selenium-containing sample solution:
(1) Sample preparation, 0.5g of tea, canola or peanut is placed in the digestive tube, followed by addition of 5mL of HNO 3 And 1mL of H 2 O 2 (30%). The tube was then shaken thoroughly and the contents were digested in a microwave digestion apparatus. After digestion was complete, the digested liquid was transferred to a glass tube and heated to near dryness. Then, 5mL of hydrochloric acid solution (6M) was added to the glass tube, and heating was continued at 150 ℃ for 1h. Finally, 1mL of potassium ferricyanide solution was added to the digest, which was then diluted to 10mL with water in a volumetric flask.
(2) To verify the reliability of the sensors, auNCs/FG sensors were used to detect selenium in food (tea, rapeseed and peanut) samples. After appropriate sample preparation, the selenium standard solution was added to the digest of the actual sample at a normalized value of 1.0 and 3.0mg/L or mg/kg, respectively. And (3) measuring the actual sample and the standard sample thereof by an Atomic Fluorescence Spectrometer (AFS), simultaneously carrying out electrochemical anodic stripping voltammetry on the diluted digestive juice, and comparing the test results of the actual sample and the standard sample. The comparison result shows that the AuNCs/FG sensor has better consistency with the result of AFS selenium test, which shows that the AuNCs/FG sensor has good reliability. Moreover, satisfactory recovery rates of 93.33% to 113.00% were obtained for the actual samples. All results are shown in table 1. The results indicate that the proposed AuNCs/FG sensor can be used for the detection of selenium in real samples.
TABLE 1 comparison of AuNCs/FG electrochemical sensor spiked recovery assay actual samples with classical methods (n = 3)
Claims (7)
1. The method for detecting selenium by using the gold nanocage/fluorinated graphene electrochemical sensor is characterized by comprising the following steps of: the method comprises the following steps: the gold nanocage/fluorinated graphene electrochemical sensor is used as a working electrode, a silver/silver chloride electrode is used as a counter electrode, a platinum column electrode is used as an auxiliary electrode, a square wave anodic stripping voltammetry is adopted for scanning based on a three-electrode system, the deposition voltage is-0.1V-0.4V, the deposition time is 180-300s, the square wave anodic stripping voltammetry peak current change is recorded, the selenium content is calculated according to a linear relation curve of the square wave anodic stripping voltammetry peak current and the selenium concentration, the gold nanocage/fluorinated graphene electrochemical sensor comprises an electrode substrate and a gold nanocage/fluorinated graphene composite material loaded on the electrode substrate, the gold nanocage/fluorinated graphene composite material comprises a nano-scale gold nanocage and a fluorinated graphene nanosheet, wherein: the gold nanocages are in a three-dimensional cage-shaped hollow porous shape, the particle size is 30-60nm, the fluorinated graphene nanosheets are in a folded and layered shape, and the gold nanocages are uniformly attached to the fluorinated graphene nanosheets.
2. The method of claim 1, wherein: the scanning window is 0.7V-1.3V; the electrolyte is 0.1-0.5M sulfuric acid electrolyte.
3. The method of claim 1, wherein: the electrode substrate is a glassy carbon electrode.
4. The method of claim 1, wherein: the preparation method of the gold nanocage/fluorinated graphene composite material comprises the following steps:
(1) Preparing a gold nanocage, namely mixing a precursor chloroauric acid and hexamethylenetetramine, then sequentially adding a polyvinylpyrrolidone protective agent, a silver nitrate crystal face regulating agent and an ascorbic acid reducing agent, stirring, and standing at room temperature for reaction to obtain a solution of the gold nanocage;
(2) Preparing fluorinated graphene, namely placing graphene in a tube furnace, removing air and impurities, and then introducing F 2 Carrying out fluorination reaction to prepare fluorinated graphene;
(3) Preparing the gold nanocage/fluorinated graphene, dispersing the fluorinated graphene in an ethanol-Nafion solution, performing ultrasonic dispersion to obtain a fluorinated graphene dispersion solution, and then adding the gold nanocage to perform ultrasonic treatment to obtain the gold nanocage/fluorinated graphene composite material.
5. The method of claim 4, wherein: standing at room temperature for 22-26 h; the molar ratio of the chloroauric acid to the hexamethylenetetramine is 1:37-1: 42; the molar ratio of the chloroauric acid to the polyvinylpyrrolidone protective agent is 1: 390-1; the molar ratio of the chloroauric acid to the silver nitrate crystal face regulating agent is 1:0.40-1:0.50, and the molar ratio of the chloroauric acid to the ascorbic acid reducing agent is 1: 1.60-1.80.
6. The method of claim 4, wherein: the step (2) is that the graphene is placed in a reactor and then placed in a tube furnace, and N is introduced 2 Removing air and impurities in the reactor, and then introducing F 2 Carrying out fluorination reaction at 165-185 ℃ for 1-2 hours in the atmosphere of F 2 / N 2 And (3) setting the ratio as 1.
7. The method of claim 4, wherein: in the step (3), the preparation of the fluorinated graphene dispersion liquid comprises the following steps: the mass fraction of Nafion in the ethanol-Nafion solution is 0.2-0.5wt.%, and the ultrasonic dispersion time is 15-25 min; the volume ratio of the fluorinated graphene dispersion liquid to the gold nanocage solution is 3-4.
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| CN109884143A (en) * | 2018-12-31 | 2019-06-14 | 中国农业科学院油料作物研究所 | It is a kind of to detect heavy metal cadmium, lead, mercury, copper, the electrochemical sensor of zinc ion and preparation method for highly sensitive synchronization |
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