CN111272839A - Preparation, application and method of electrochemical sensor based on nanocomposite materials - Google Patents

Abstract

The invention discloses the preparation, application and method of an electrochemical sensor based on nanocomposite materials. The preparation of the electrochemical sensor based on nanocomposite materials includes the following steps: preparing zinc oxide; preparing rGO/ZnO nanocomposite materials; preparing chemically modified electrodes . The electrochemical sensor was applied to detect the content of metal ions Cd(Ⅱ) and Pb(Ⅱ) in water. The application method of the electrochemical sensor based on the nanocomposite material includes the following steps: preparing a standard solution and a river water sample solution; detecting by square wave anodic stripping voltammetry; and measuring the recovery rate. The invention uses the rGO/ZnO nanocomposite material as the modified electrode, which increases the surface area and conductivity of the electrode, and effectively improves the sensing performance of the electrode. selectivity and sensitivity.

Description

Preparation, application and method of electrochemical sensor based on nanocomposite materials

technical field

The invention relates to the preparation, application and method of an electrochemical sensor based on nano-composite materials, in particular to the preparation of an electrochemical sensor based on rGO/ZnO nano-composite materials and its application to detect metal ions Cd(II) and Pb in water (II) The content method belongs to the technical field of chemically modified electrodes and environmental electrochemical analysis.

Background technique

In recent years, carbon-based nanomaterials, such as carbon nanotubes, fullerenes, and graphene oxide (GO), have been widely used in electrochemical detection due to their excellent physicochemical properties. Graphene, as a single-layer graphite, has been widely used in many fields, including energy storage, due to its unique inherent properties, such as high specific surface area, good biocompatibility, excellent electron transport, and high mechanical strength. , supercapacitors, drug delivery devices and electrochemical sensors, etc. However, due to van der Waals forces and π-π recrystallization, the layered structure of graphene is very unstable and prone to aggregation and even recombination into graphite. Therefore, it needs to be combined with other materials to improve this disadvantage.

In a large number of metal oxide studies, zinc oxide (ZnO) is considered to be a non-toxic, thermally stable and electrochemically active transition metal oxide. Compared with other nanoparticles, ZnO has the advantages of high surface modification efficiency, strong adsorption performance, fast electron transfer speed, good biocompatibility, and large specific surface area. Therefore, ZnO nanoparticles can be used to develop high-sensitivity electrochemical sensors.

With the gradual improvement of people's living standards, the impact of heavy metal pollution on humans has become more and more obvious. Among them, Cd(II) and Pb(II) are very common heavy metal ions, which will cause certain negative effects on the body in the human body. Long-term exposure to cadmium can lead to chronic poisoning and kidney damage. In very low concentrations, lead can damage the human nervous system, blood circulation, kidneys and reproductive system. Moreover, unlike degradable organic pollutants, heavy metals can accumulate in organisms through the food chain, posing a serious threat to animal and human health. Therefore, low-cost, sensitive, and rapid analysis of trace heavy metal ions in the environment is very important.

So far, many analytical methods have been used to analyze heavy metal ions, such as atomic absorption spectrometry, inductively coupled plasma mass spectrometry, surface-enhanced Raman scattering, and x-ray fluorescence spectroscopy. Although these methods can be used for the detection of heavy metal ions, they require relatively expensive instruments, the application of complicated operating procedures and a long detection time.

SUMMARY OF THE INVENTION

In order to solve the shortcomings of the above-mentioned technologies, the present invention provides the preparation, application and method of an electrochemical sensor based on nanocomposite materials.

In order to solve the above technical problems, the technical scheme adopted in the present invention is: the preparation of the electrochemical sensor based on nano-composite material, the preparation method comprises the following steps:

Step 1: Preparation of Zinc Oxide

Dissolve a certain amount of NaOH and ZnSO ₄ in the beaker respectively, and then add the NaOH solution dropwise to the ZnSO ₄ solution under constant stirring to form a white Zn(OH) ₂ suspension, and then this suspension Transferred to the reactor, pyrolyzed for a period of time at an appropriate temperature, and the obtained solid was filtered, washed and dried to obtain a zinc oxide solid when it was lowered to room temperature;

Step 2: Preparation of rGO/ZnO nanocomposites

Graphene oxide was prepared by Hummers method, a certain amount of graphene oxide powder was dissolved in 100 mL of water to make a uniformly dispersed suspension, appropriate ascorbic acid was added, stirred evenly, and a certain amount of ZnO powder obtained in step 1 was mixed. Adding into the above solution, stirring and reacting for a period of time at a certain temperature, after the reaction is completed, the obtained solid is filtered, washed and dried to obtain rGO/ZnO nanocomposite material;

Step 3: Preparation of chemically modified electrodes

A certain amount of rGO/ZnO nanocomposite was dispersed on the surface of the glassy carbon electrode GCE by the drop coating method, and dried under an infrared lamp to obtain the chemically modified electrode rGO/ZnO/GCE.

Further, the consumption of NaOH in step 1 is 0.68g, and the consumption of ZnSO ₄ is 3.22g; the condition of the pyrolysis reaction in the reaction kettle is to react at 150° C. for 12h.

Further, in step 2, the amount of graphene oxide is 0.1 g, the amount of ascorbic acid is 1 g, and the amount of ZnO powder added is 0.3 g; the condition of the liquid phase reaction is heating at 45 ° C for 12 h.

Further, the drying conditions in step 1 and step 2 are both drying at 50° C. for 12 h.

Further, in step 3, the volume of the rGO/ZnO nanocomposite dispersion liquid is 7 μL, and the concentration is 1 mg/mL.

An application of an electrochemical sensor based on nanocomposite materials, the electrochemical sensor is applied to the detection of the content of metal ions Cd(II) and Pb(II) in water.

An application method of an electrochemical sensor based on a nanocomposite material, the detection method comprises the following steps:

I. Prepare 5×10 ^-3 mol/L metal ion Cd(Ⅱ), Pb(Ⅱ) standard solutions and river water sample solutions respectively;

II. Using the prepared chemically modified electrode rGO/ZnO/GCE as the working electrode, platinum wire as the counter electrode, and silver/silver chloride as the reference electrode, the Cd(II) concentrations of different concentrations were detected by square wave anodic stripping voltammetry , Pb(Ⅱ) standard solution, respectively record the relationship between the oxidation peak current value and its concentration and establish a standard curve;

III. Measure the sample solution prepared in step I, and further adopt the standard addition method to add Cd(II) and Pb(II) standard solutions to the above-mentioned sample solution respectively, and measure the recovery rate.

Further, the preparation method of 5×10 ^-3 mol/L Pb(II) standard solution in step I is as follows: weigh 0.1656g Pb(NO ₃ ) ₂ , dissolve it with a small amount of water, and then use distilled water to dilute to a 100mL volumetric flask; Then take a certain amount of Pb(Ⅱ) standard solution and dilute it with pH=5.0 HAc-NaAc buffer solution to different concentrations: 1 μmol/L, 0.9 μmol/L, 0.8 μmol/L, 0.7 μmol/L, 0.6 μmol /L, 0.5μmol/L, 0.4μmol/L, 0.3μmol/L, 0.2μmol/L, 0.1μmol/L, 0.005μmol/L.

Further, the preparation method of 5×10 ^-3 mol/L Cd(II) standard solution in step I is as follows: weigh 0.1283g of CdSO ₄ ·8H ₂ O, dissolve with a small amount of water, and then use distilled water to dilute to a 100mL volumetric flask; Take a certain amount of Cd(Ⅱ) standard solution and dilute it with pH=5.0 HAc-NaAc buffer solution to different concentrations: 1 μmol/L, 0.9 μmol/L, 0.8 μmol/L, 0.7 μmol/L, 0.6 μmol/L L, 0.5 μmol/L, 0.4 μmol/L, 0.3 μmol/L, 0.2 μmol/L, 0.1 μmol/L, 0.01 μmol/L.

Further, the preparation method of the sample solution in the step 1 is: the actual water sample and the HAc-NaAc buffer solution are diluted for subsequent use according to 1:1.

The invention uses the rGO/ZnO nanocomposite material as the modified electrode, which increases the surface area and conductivity of the electrode, effectively improves the sensing performance of the electrode, and is used in the determination of the content of metal ions Cd(II) and Pb(II). It has good selectivity and sensitivity, and does not require expensive instruments, which saves detection time. At the same time, the electrochemical method has the advantages of high sensitivity, low cost, good portability, and simple operation, and can achieve rapid and effective analysis of heavy metals.

Description of drawings

Figure 1 is the SEM images of different nanomaterials ZnO (a), rGO (b), and rGO/ZnO (c) of the present invention.

Figure 2 shows the cyclic voltammetry curves of different working electrodes Bare, rGO, ZnO, and rGO/ZnO in 1mmol/LK ₃ [Fe(CN) ₆ ]/K ₄ [Fe(CN) ₆ ] solution.

Figure 3 shows the electrochemical impedance curves of different working electrodes Bare, rGO, ZnO, and rGO/ZnO in 1mmol/LK ₃ [Fe(CN) ₆ ]/K ₄ [Fe(CN) ₆ ] solution.

Figure 4 shows the square wave anodic dissolution volts of 0.5 μM Pb(II) and Cd(II) detected by different working electrodes Bare, rGO, ZnO and rGO/ZnO in 0.1M HAc-NaAc buffer solution at pH=5. An inspection curve.

Figure 5 shows the square wave anodic stripping voltammetry curves of different concentrations of Pb(II) on rGO/ZnO/GCE: (a) Pb(II) concentration from low to high is 0.005 μmol/L, 0.1 μmol/L, 0.2 μmol/L μmol/L, 0.3 μmol/L, 0.4 μmol/L, 0.5 μmol/L, 0.6 μmol/L, 0.7 μmol/L, 0.8 μmol/L, 0.9 μmol/L, 1.0 μmol/L.

Figure 6 shows the square wave anodic stripping voltammetry curves of different concentrations of Cd(II) on rGO/ZnO/GCE: (b) Cd(II) concentrations from low to high are 0.01 μmol/L, 0.1 μmol/L, 0.2 μmol/L, 0.3 μmol/L, 0.4 μmol/L, 0.5 μmol/L, 0.6 μmol/L, 0.7 μmol/L, 0.8 μmol/L, 0.9 μmol/L, 1.0 μmol/L.

Detailed ways

The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

The preparation of the nanocomposite-based electrochemical sensor as shown in Figure 1-6, the preparation method includes the following steps:

Step 1: Preparation of Zinc Oxide

Dissolve a certain amount of NaOH and ZnSO ₄ in the beaker respectively, and then add the NaOH solution dropwise to the ZnSO ₄ solution under constant stirring to form a white Zn(OH) ₂ suspension, and then this suspension Transferred to the reactor, pyrolyzed for a period of time at an appropriate temperature, and the obtained solid was filtered, washed and dried to obtain a zinc oxide solid when it was lowered to room temperature;

Step 2: Preparation of rGO/ZnO nanocomposites

Graphene oxide was prepared by Hummers method, a certain amount of graphene oxide powder was dissolved in 100 mL of water to make a uniformly dispersed suspension, appropriate ascorbic acid was added, stirred evenly, and a certain amount of ZnO powder obtained in step 1 was mixed. Adding into the above solution, stirring and reacting for a period of time at a certain temperature, after the reaction is completed, the obtained solid is filtered, washed and dried to obtain rGO/ZnO nanocomposite material;

Step 3: Preparation of chemically modified electrodes

A certain amount of rGO/ZnO nanocomposite was dispersed on the surface of the glassy carbon electrode GCE by the drop coating method, and dried under an infrared lamp to obtain the chemically modified electrode rGO/ZnO/GCE.

In step 1, the amount of NaOH was 0.68 g, and the amount of ZnSO ₄ was 3.22 g; the conditions of the pyrolysis reaction in the reaction kettle were 12h at 150°C.

In step 2, the consumption of graphene oxide is 0.1g, the consumption of ascorbic acid is 1g, and the amount of ZnO powder added is 0.3g; the condition of the liquid phase reaction is heating for 12h at 45°C.

The drying conditions in step 1 and step 2 are both drying at 50° C. for 12 h.

In step 3, the volume of the rGO/ZnO nanocomposite dispersion liquid is 7 μL, and the concentration is 1 mg/mL.

An application of an electrochemical sensor based on nanocomposite materials, the electrochemical sensor is applied to the detection of the content of metal ions Cd(II) and Pb(II) in water.

An application method of an electrochemical sensor based on a nanocomposite material, the detection method comprises the following steps:

I. Prepare 5×10 ^-3 mol/L metal ion Cd(Ⅱ), Pb(Ⅱ) standard solutions and river water sample solutions respectively;

II. Using the prepared chemically modified electrode rGO/ZnO/GCE as the working electrode, platinum wire as the counter electrode, and silver/silver chloride as the reference electrode, different concentrations of Cd were detected by square wave anodic stripping voltammetry (SWASV). (II) and Pb(II) standard solutions, respectively record the relationship between the oxidation peak current value and its concentration and establish a standard curve;

III. Measure the sample solution prepared in step I, and further adopt the standard addition method to add Cd(II) and Pb(II) standard solutions to the above-mentioned sample solution respectively, and measure the recovery rate.

The preparation method of the 5×10 ^-3 mol/L Pb(II) standard solution in step I is as follows: Weigh 0.1656g of Pb(NO ₃ ) ₂ , dissolve it with a small amount of water, and then use distilled water to dilute to a 100mL volumetric flask; then take the A certain amount of Pb(Ⅱ) standard solution was gradually diluted with pH=5.0 HAc-NaAc buffer solution to different concentrations: 1 μmol/L, 0.9 μmol/L, 0.8 μmol/L, 0.7 μmol/L, 0.6 μmol/L ,0.5μmol/L,0.4μmol/L,0.3μmol/L,0.2μmol/L,0.1μmol/L,0.005μmol/L.

The preparation method of 5×10 ^-3 mol/L Cd(II) standard solution in step I is as follows: weigh 0.1283g of CdSO ₄ ·8H ₂ O, dissolve it with a small amount of water, and then use distilled water to dilute to a 100mL volumetric flask; The standard solution of Cd(Ⅱ) was diluted stepwise with pH=5.0 HAc-NaAc buffer solution to different concentrations: 1 μmol/L, 0.9 μmol/L, 0.8 μmol/L, 0.7 μmol/L, 0.6 μmol/L, 0.5μmol/L, 0.4μmol/L, 0.3μmol/L, 0.2μmol/L, 0.1μmol/L, 0.01μmol/L.

The preparation method of the sample solution in the step 1 is as follows: the actual water sample and the HAc-NaAc buffer solution are diluted 1:1 for subsequent use.

In the present invention, nano-zinc oxide powder is prepared by hydrothermal reaction, graphene oxide is reduced by ascorbic acid, and nano-zinc oxide powder is added in the reduction process to prepare two-dimensional nano-composite material rGO/ZnO, which is used as an electrode modification material, and is used as an electrode modification material. The corresponding modified electrode (rGO/ZnO/GCE) was prepared by direct drop coating method to immobilize it on the surface of glassy carbon electrode.

The metal ions Cd(II) and Pb(II) in water were detected by square wave anodic stripping voltammetry. The morphology and structure of the nanocomposite were studied by means of scanning electron microscopy, and it was found that ZnO was uniformly attached to the layered structure of reduced graphene oxide (rGO), forming more adsorption centers.

The electrochemical properties of rGO/ZnO/GCE were characterized by cyclic voltammetry and electrochemical impedance spectroscopy, and the results showed that rGO/ZnO/GCE had good electrochemical properties. In the experiments, pH, deposition time and deposition potential were optimized. Under the optimal conditions, the detection ranges of Cd(Ⅱ) and Pb(Ⅱ) were 0.01-1μM and 0.005-1μM, respectively, and the detection limits were 3.33nM and 1.67nM, respectively.

Figure 1 is the SEM images of different nanomaterials ZnO (a), rGO (b) and rGO/ZnO (c). It can be seen from Figure 1(a) that the prepared ZnO powder has a lamellar structure with uniform size, uniform dispersion and a certain thickness. It can be seen from Fig. 1(b) that rGO has a flake-like structure, which is loose and porous, and there are many folds and protrusions. It can be seen from Figure 1(c) that the ZnO nanosheets have been successfully recombined to the surface of rGO, preventing the agglomeration of rGO, which is beneficial to the adsorption of metal ions.

Figure 2 shows the cyclic voltammetry curves of different working electrodes Bare, rGO, ZnO, and rGO/ZnO in 1mmol/LK ₃ [Fe(CN) ₆ ]/K ₄ [Fe(CN) ₆ ] solution. It can be seen from Fig. 2 that compared with the bare electrode Bare, the anodic current and cathodic current of the ZnO modified electrode are significantly reduced, which can reflect that the ZnO attached to the electrode surface hinders the Fe(CN) ₆ ^3- /Fe(CN ) ₆ ^4- The transfer of electrons in the redox process. The anodic and cathodic currents of the rGO-modified electrodes were significantly enhanced, indicating that rGO has high electrocatalytic activity and excellent ionic conductivity. After ZnO was compounded on rGO, the current intensity decreased, which may be because ZnO hindered the transfer of surface electrons.

Figure 3 is the measurement of different working electrodes Bare, rGO, ZnO, rGO/ZnO in 1 mmol/LK ₃ [Fe(CN) ₆ ]/K ₄ [Fe(CN) ₆ ] in 0.1 mol/L KCl solution using Nyquist Figure represents the electrochemical impedance curve graph. It can be seen from Figure 3 that the resistance of the bare electrode is 236.4 Ω, and after the working electrode is modified with ZnO, the resistance becomes 3400 Ω, which is due to the low conductivity of ZnO hindering the transfer of electrons on the electrode surface. The measured resistance of the rGO-modified electrode is 516.3 Ω, which also proves the excellent electrical conductivity of rGO. The detected resistance of the rGO/ZnO modified electrode is 1300Ω, which is significantly lower than that of ZnO, which indicates that the addition of rGO greatly promotes the transfer of electrons on the electrode surface. This result is consistent with the above-mentioned cyclic voltammetry (CV) results, indicating that rGO/ZnO nanomaterials have been successfully synthesized.

Figure 4 shows the square wave anodic stripping voltammetry of 0.5 μM Pb(II) and Cd(II) in 0.1 M HAc-NaAc buffer solution at pH 5 for different working electrodes Bare, rGO, ZnO, and rGO/ZnO. detection. Under the detection conditions of deposition potential of -1.2V, deposition time of 210s, and detection range of -1.2V to -0.2V, it can be seen from Figure 4 that the electrochemical response of the bare electrode to the two ions is very small, and the sensitivity is higher than Low. The electrochemical response of the ZnO-modified electrode to the two ions is better than that of the bare electrode and the rGO-modified electrode, indicating that ZnO has good adsorption performance, but considering its poor conductivity, after compounding it on rGO, the As can be seen in Figure 4, the electrochemical detection of the two ions by the rGO/ZnO modified electrode obtained a higher peak current, and the detection sensitivity was also significantly improved. It may be attributed to the large specific surface area and excellent electrical conductivity of rGO that the nanomaterial-modified rGO/ZnO produced a good electrochemical response. Combined with the previous cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), the rGO/ZnO modified electrode was selected for electrochemical detection of the two metal ions.

Under the optimal experimental conditions, the SWASV curves of different concentrations of Cd(II) and Pb(II) were measured with rGO/ZnO modified electrodes, and the corresponding standard curves were drawn. The results are shown in Figure 5. It can be seen from Figure 5(a) that the detection potential of Pb(II) is about -0.57V. In the range of 5nM~1μM, the Pb(II) ion concentration has a certain linear relationship with the peak current. The linear equation It is i/μA=1.8387+29.73c/μM, the correlation coefficient is 0.9980, and the detection limit is 1.7nM. As can be seen from Fig. 6(b), the detection potential of Cd(II) is about -0.8V. The experiment found that in the concentration range of 0.01μM～1μM, the Cd(Ⅱ) ion concentration and the peak current showed a good linear relationship, the linear equation was i/μA=0.8079+25.66c/μM, the correlation coefficient was 0.9895, and the detection limit was 3.3nM.

The present invention will be described in further detail below in conjunction with the embodiments.

Example 1:

The preparation of electrochemical sensors based on nanocomposites includes the following steps:

Step 1: Preparation of Zinc Oxide

Dissolve 0.68g NaOH and 3.22g ZnSO ₄ in the beaker respectively, then add the NaOH solution dropwise to the ZnSO ₄ solution under constant stirring to form a white Zn(OH) ₂ suspension, then transfer this suspension In the reaction kettle, react at 150 ° C for 12 h, and after the solid is cooled to room temperature, the obtained solid is filtered, washed and dried to obtain zinc oxide solid;

Step 2: Preparation of rGO/ZnO nanocomposites

Graphene oxide was prepared by Hummers method, 0.1 g of the obtained graphene oxide powder was dissolved in 100 mL of water to form a uniformly dispersed suspension, 1 g of ascorbic acid was added, and 0.3 g of the ZnO powder obtained in step 1 was added. Add to the above solution, stir the reaction at 45 °C and heat for 12 h. After the reaction is completed, the obtained solid is filtered and washed and dried at 50 °C for 12 h. After drying, the rGO/ZnO nanocomposite is obtained.

Step 3: Preparation of chemically modified electrodes

The rGO/ZnO nanocomposite material with a volume of 7 μL and a concentration of 1 mg/mL was dispersed on the surface of the glassy carbon electrode GCE by the drop coating method, and dried under an infrared lamp to obtain the chemically modified electrode rGO/ZnO/GCE.

An application of an electrochemical sensor based on nanocomposite materials, which is applied to the content detection of metal ions Cd(II) and Pb(II) in water.

An application method of an electrochemical sensor based on a nanocomposite material, the detection method comprises the following steps:

I. Prepare 5×10 ^-3 mol/L metal ion Cd(Ⅱ), Pb(Ⅱ) standard solutions and river water sample solutions respectively;

The preparation method of 5×10 ^-3 mol/L Pb(Ⅱ) standard solution is as follows: Weigh 0.1656g Pb(NO ₃ ) ₂ , dissolve it with a small amount of water, and then dilute to a 100mL volumetric flask with distilled water; then take a certain amount of Pb(NO 3 ) 2 (II) The standard solution was gradually diluted with pH=5.0 HAc-NaAc buffer solution to different concentrations: 1 μmol/L, 0.9 μmol/L, 0.8 μmol/L, 0.7 μmol/L, 0.6 μmol/L, 0.5 μmol /L, 0.4 μmol/L, 0.3 μmol/L, 0.2 μmol/L, 0.1 μmol/L, 0.005 μmol/L.

The preparation method of 5×10 ^-3 mol/L Cd(Ⅱ) standard solution is as follows: Weigh 0.1283g of CdSO ₄ ·8H ₂ O, dissolve with a small amount of water, and then dilute to a 100mL volumetric flask with distilled water; take a certain amount of Cd( Ⅱ) The standard solution was gradually diluted with pH=5.0 HAc-NaAc buffer solution to different concentrations: 1 μmol/L, 0.9 μmol/L, 0.8 μmol/L, 0.7 μmol/L, 0.6 μmol/L, 0.5 μmol /L, 0.4 μmol/L, 0.3 μmol/L, 0.2 μmol/L, 0.1 μmol/L, 0.01 μmol/L.

The preparation method of the sample solution is: dilute the actual water sample and HAc-NaAc buffer solution according to 1:1 for use.

II. Using the prepared chemically modified electrode rGO/ZnO/GCE as the working electrode, platinum wire as the counter electrode, and silver/silver chloride as the reference electrode, the Cd(II) concentrations of different concentrations were detected by square wave anodic stripping voltammetry , Pb(Ⅱ) standard solution, respectively record the relationship between the oxidation peak current value and its concentration and establish a standard curve;

III. Measure the sample solution prepared in step I, and further adopt the standard addition method to add Cd(II) and Pb(II) standard solutions to the above-mentioned sample solution respectively, and measure the recovery rate.

In order to test the practicability of the modified electrode, the real water sample was tested, and the actual water sample was taken from the Licun River in Qingdao City. The actual water sample was diluted 1:1 with the buffer solution of HAc-NaAc, and Cd( II) and standard addition of Pb(II), SWASV detection was carried out to determine the recovery rate, and the results are shown in Table 1.

Table 1. rGO/ZnO modified electrode detects Pb(II) and Cd(II) in real water samples

The method was applied to the determination of metal ions Cd(II) and Pb(II) in water, and the recovery rate in the sample addition test was 94.00%-114.00%, and the results were satisfactory.

The above-mentioned embodiments are not intended to limit the present invention, and the present invention is not limited to the above-mentioned examples. Changes, modifications, additions or replacements made by those skilled in the art within the scope of the technical solutions of the present invention also belong to the present invention. the scope of protection of the invention.

Claims (10)

1. the preparation of the electrochemical sensor based on nanocomposite material, is characterized in that: described preparation method comprises the following steps: Step 1: Preparation of Zinc Oxide Dissolve a certain amount of NaOH and ZnSO ₄ in the beaker respectively, and then add the NaOH solution dropwise to the ZnSO ₄ solution under constant stirring to form a white Zn(OH) ₂ suspension, and then this suspension Transferred to the reactor, pyrolyzed for a period of time at an appropriate temperature, and the obtained solid was filtered, washed and dried to obtain a zinc oxide solid when it was lowered to room temperature; Step 2: Preparation of rGO/ZnO nanocomposites Graphene oxide was prepared by Hummers method. Dissolve a certain amount of graphene oxide powder in 100 mL of water to form a uniformly dispersed suspension, add appropriate ascorbic acid, stir evenly, and add a certain amount of ZnO powder prepared in step 1 to the In the above solution, the reaction is stirred at a certain temperature for a period of time, and after the reaction is completed, the obtained solid is filtered, washed and dried to obtain the rGO/ZnO nanocomposite material; Step 3: Preparation of chemically modified electrodes A certain amount of rGO/ZnO nanocomposite was dispersed on the surface of glassy carbon electrode GCE by drop coating method, and then dried under infrared lamp to obtain chemically modified electrode rGO/ZnO/GCE. 2. the preparation of the electrochemical sensor based on nanocomposite material according to claim 1, is characterized in that: the consumption of NaOH is 0.68g in the described step ₁ , and the consumption of ZnSO is 3.22g; The reaction conditions were 12h at 150°C. 3. the preparation of the electrochemical sensor based on nanocomposite material according to claim 1, is characterized in that: the consumption of graphene oxide is 0.1g in described step 2, the consumption of ascorbic acid is 1g, the amount that adds ZnO powder It is 0.3g; the condition of liquid-phase reaction is heating at 45 ℃ for 12h. 4 . The preparation of the nanocomposite-based electrochemical sensor according to claim 1 , wherein the drying conditions in the first and second steps are both drying at 50° C. for 12 hours. 5 . 5 . The preparation of the nanocomposite-based electrochemical sensor according to claim 1 , wherein in the step 3, the volume of the rGO/ZnO nanocomposite dispersion liquid is 7 μL, and the concentration is 1 mg/mL. 6 . 6 . An application of the electrochemical sensor based on nanocomposite materials prepared by claim 1 , wherein the electrochemical sensor is applied to the detection of the content of metal ions Cd(II) and Pb(II) in water. 7 . 7. An application method of an electrochemical sensor based on nanocomposite material as claimed in claim 6, characterized in that: the detection method comprises the following steps: I. Prepare 5×10 ^-3 mol/L metal ion Cd(Ⅱ), Pb(Ⅱ) standard solutions and river water sample solutions respectively; II. Using the prepared chemically modified electrode rGO/ZnO/GCE as the working electrode, platinum wire as the counter electrode, and silver/silver chloride as the reference electrode, different concentrations of Cd(II) were detected by square wave anodic stripping voltammetry , Pb(Ⅱ) standard solution, respectively record the relationship between the oxidation peak current value and its concentration and establish a standard curve; III. Measure the sample solution prepared in step I, and further use the standard addition method to add Cd(II) and Pb(II) standard solutions to the above-mentioned sample solution respectively, and measure the recovery rate. 8. The application method of the nanocomposite-based electrochemical sensor according to claim 7, characterized in that: the preparation method of the 5× ^10-3 mol/L Pb(II) standard solution in the step I is: weighing Take 0.1656g of Pb(NO ₃ ) ₂ , dissolve it with a small amount of water, and then dilute it to a 100-mL volumetric flask with distilled water; Different concentrations: 1μmol/L, 0.9μmol/L, 0.8μmol/L, 0.7μmol/L, 0.6μmol/L, 0.5μmol/L, 0.4μmol/L, 0.3μmol/L, 0.2μmol/L, 0.1μmol/ L, 0.005 μmol/L. 9. The application method of the nanocomposite-based electrochemical sensor according to claim 7, wherein the preparation method of the 5× ^10-3 mol/L Cd(II) standard solution in the step I is: weighing Take 0.1283g of CdSO ₄ ·8H ₂ O, dissolve it with a small amount of water, and then dilute the volume to a 100mL volumetric flask with distilled water; take a certain amount of Cd(Ⅱ) standard solution and dilute it with pH=5.0 HAc-NaAc buffer solution to different Concentration: 1μmol/L, 0.9μmol/L, 0.8μmol/L, 0.7μmol/L, 0.6μmol/L, 0.5μmol/L, 0.4μmol/L, 0.3μmol/L, 0.2μmol/L, 0.1μmol/L ,0.01μmol/L. 10. the application method of the electrochemical sensor based on nanocomposite material according to claim 7, is characterized in that: the compound method of sample solution in described step 1 is: actual water sample and HAc-NaAc buffer solution are according to 1: 1 for dilution.

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