A method for preparing a hydrogen peroxide electrochemical sensor

Abstract

The application discloses a preparation method of a hydrogen peroxide electrochemical sensor, and steps of the method comprise the following steps: graphene (GO) dispersion liquid preparation, taking 2 mg / mL graphene in ultrapure water, ultrasonic mixing with 1% chitosan solution in a volume ratio of 5:1; Pt-Pd NPs electrodeposition liquid preparation, taking 2 mmol / L chloroplatinic acid solution and 2 mmol / L potassium chloropalladate solution to obtain a 0.2 mol / L H2SO4 mixed solution; GCE pretreatment, respectively using 0.3 μm and 0.05 μm alumina powder to polish on the suede in sequence until the surface is mirror smooth, then washing with ultrapure water for 5 minutes; GO / GCE modified electrode preparation, after blowing dry GCE with N2 flow, immediately adding GO dispersion liquid to the electrode surface. By using the preparation method, a high-performance novel hydrogen peroxide electrochemical sensor is prepared. Through the synergistic effect of several nanomaterials, the prepared Pt-Pd-GO / GCE enzyme-free sensor has a wide detection range (31.2 nmol / L~92.2 μmol / L), a low detection limit (31.2 nmol / L) and an anti-interference ability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensor preparation, in particular to a preparation method of a hydrogen peroxide electrochemical sensor. BACKGROUND

[0002] In recent years, a lot of research work has been done on the detection of hydrogen peroxide (H2O2), because hydrogen peroxide has a wide range of uses in the fields of environmental protection, food hygiene, clinical diagnosis and chemical industry. Hydrogen peroxide is an important chemical product, but it is also a very dangerous substance, and if it is used in excess, it will have many adverse effects on the environment. In addition, hydrogen peroxide is the most widely distributed active oxygen free radical in the mammalian body in clinical medicine, which is mainly derived from superoxide free radicals. Because it has a long life, it can diffuse into various organelles in cells, and is considered to be one of the main components causing oxidative stress. At the same time, it is also considered to be one of the main components causing oxidative stress, and is the most valuable marker for many diseases. Hydrogen peroxide has a very important influence on people's life, environmental pollution, health, social progress, etc., and its rapid, accurate and effective detection is imperative.

[0003] At present, there are many methods for quantitatively detecting the release of hydrogen peroxide by cells, such as fluorescence analysis, chemiluminescence, chromatography, spectrophotometry, and electrochemical analysis. Among them, the electrochemical method is favored by people because of its simple operation, high sensitivity, wide linear range, rapid and stable response signal, etc. However, most of the biological sensors based on hemoglobin and peroxidase have the disadvantages of poor stability of the enzyme itself, easy loss of activity, etc., which to some extent limit the application of the sensor. Therefore, it is of great significance to seek a new enzyme-free sensor to detect H2O2.

[0004] Various electrode materials have been applied to detection, such as carbon-based materials, conductive polymers, etc. Carbon-based materials are the most widely used and the most diverse materials at present, among which graphene is a crystal with a two-dimensional honeycomb lattice structure formed by the close packing of single-layer carbon atoms. The thickness of the graphite crystal film is only 0.335 nm, and its unique two-dimensional structure makes it have excellent electrical, mechanical, thermal and chemical properties. Because of its excellent electron transfer performance and large specific surface area, it provides many advantages for the construction of electrochemical sensors. Graphene can be used as a scaffold for nanomaterials to form composite nanomaterials. Especially, decorating the surface of graphene with metal nanoparticles can significantly increase the electrochemically active surface area and effectively accelerate the electron transfer between the electrode and the measured substance, thereby providing a rapid and sensitive current response. Currently, the loaded metal nanoparticles mainly include noble metals such as Pt, Au, Pb and Pd. Platinum and palladium belong to the platinum group elements and have similar structures. They have high particle stability, good biocompatibility and conductivity. In addition, it has been reported that Pt and Pd have good catalytic activity for the oxidation and reduction of H2O2, which can effectively reduce the oxidation and reduction overpotential of H2O2 and can be used for high-sensitivity detection.

[0005] In view of the above numerous advantages of graphene and platinum / palladium nanoparticles, it is urgent to combine them for real-time and rapid detection of hydrogen peroxide by taking advantage of the excellent conductivity and large specific surface area of graphene and the electrocatalytic performance of platinum / palladium nanoparticles. SUMMARY

[0006] The purpose of the present application is to provide a preparation method of a hydrogen peroxide electrochemical sensor.

[0007] To achieve the above purpose, the present application provides the following technical scheme: a preparation method of a hydrogen peroxide electrochemical sensor, comprising the following steps:

[0008] S1, preparation of a GO dispersion liquid, taking graphene with a volume concentration of 2 mg / mL in ultrapure water and fully ultrasonicating, and mixing with a chitosan solution with a mass fraction of 1% at a volume ratio of 5:1;

[0009] S2, preparation of a Pt-Pd NPs electrodeposition liquid, taking 2 mmol / L chloroplatinic acid solution and 2 mmol / L potassium chloropalladate solution and mixing with 0.2 mol / L H2SO4;

[0010] S3, pretreatment of GCE, polishing the surface on the buffing leather with 0.3 μm and 0.05 μm alumina powder in turn until the surface is mirror smooth, and then washing with ultrapure water for 5 minutes;

[0011] S4, making GO / GCE modified electrode, after blowing dry GCE with N2 flow, immediately adding GO dispersion liquid to electrode surface, drying for three hours at room temperature to obtain GO / GCE modified electrode, before use, needing to repeat soaking-drying twice with distilled water to remove nano materials not fixed on the surface of GO / GCE modified electrode;

[0012] S5, electrodeposition of Pt-Pd NPs on GO / GCE modified electrode.

[0013] Preferably, electrodeposition of Pt-Pd NPs is in 0.2 mol / L H2SO4 solution containing 2 mmol / L H2PtCl6 and 2 mmol / L KPdCl4, scanning for a certain number of times, potential window is-0.4 V to +0.6 V, and scanning speed is 50 mV / s.

[0014] Preferably, there is also step S6, after electrodeposition, cleaning electrode with a large amount of deionized water, drying at room temperature, after preparation of modified electrode Pt-Pd-GO / GCE, storing at room temperature.

[0015] Preferably, the modified volume of GO dispersion liquid is 2 μL-10 μL.

[0016] Preferably, the scanning number of times is 8-18 times.

[0017] Preferably, the volume of GO dispersion liquid is 8 μL, and the scanning number of times is 16 times for electrodeposition.

[0018] Preferably, the working potential of the hydrogen peroxide electrochemical sensor is-0.05 V.

[0019] Compared with the prior art, the beneficial effects of the present application are:

[0020] By using the preparation method, a high-performance new hydrogen peroxide electrochemical sensor is prepared. Through the synergistic effect of several nano materials, the prepared Pt-Pd-GO / GCE enzyme-free sensor has a wide detection range (31.2 nmol / L-92.2 μmol / L), a low detection limit (31.2 nmol / L), and an anti-interference ability. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0022] Figure 1A~C are schematic diagrams of different modification volumes and scanning numbers of GO in the application;

[0023] Figure 2 A~B are comparative schematic diagrams of bare glassy carbon electrode (GCE), graphene modified electrode (GO / GCE), palladium-platinum nanoparticle modified electrode (Pd-Pt / GCE) and palladium-platinum-graphene nanocomposite modified electrode (Pd-Pt-GO / GCE) in the application;

[0024] Figure 3 It is a schematic diagram for investigating the electrocatalytic reduction performance of Pd-Pt-GO / GCE on hydrogen peroxide by CV technology in the application;

[0025] Figure 4 A~B are determination diagrams of the optimal reduction potential of Pd-Pt-GO / GCE on hydrogen peroxide, using chronoamperometry (i-t) in the application;

[0026] Figure 5 It is a schematic diagram for comparing the detection sensitivity of several different modified electrodes on hydrogen peroxide by i-t technology in the application;

[0027] Figure 6 A~B are determination diagrams of continuously adding different concentrations of hydrogen peroxide to deoxygenated PBS (0.02 mol / L, pH 7.4) solution in the application;

[0028] Figure 7 It is a schematic diagram for testing the anti-interference ability of Pt-Pd-GO / GCE sensor in the application;

[0029] Figure 8 It is a preparation flowchart of Pt-Pd-GO in the application. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the application more clear, the application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the application, and are not used to limit the application.

[0031] Please refer to Figure 8 The preparation method of a hydrogen peroxide electrochemical sensor is shown in the figure, and the preparation method is as follows:

[0032] First, the preparation of Pt-Pd-GO modified electrode

[0033] 1. Preparation of GO dispersion: first, take a certain volume concentration of 2 mg / mL graphene in ultrapure water and ultrasonically mix with 1% chitosan solution in a volume ratio of 5:1;

[0034] Preparation of Pt-Pd NPs: 2 mmol / L chloroplatinic acid solution and 2 mmol / L potassium chloropalladate solution were mixed with 0.2 mol / L H2SO4.

[0035] 2. Before use, the glassy carbon electrode (GCE, 3 mm in diameter) was polished on suede with 0.3 μm and 0.05 μm alumina powder respectively until the surface was mirror-smooth. Then, it was washed with ultrapure water for 5 minutes and dried with N2 gas flow. A certain volume of GO was immediately added to the electrode surface. The modified electrode was dried at room temperature for three hours. Before use, it was necessary to repeat the soaking and drying with distilled water twice to remove the unfixed nanomaterials on the surface of the modified electrode.

[0036] 3. Electrodeposition of platinum / palladium nanoparticles (Pt-Pd NPs) onto the GO / GCE modified electrode was primarily performed using cyclic voltammetry (CV). Pt-Pd NPs were deposited in a 0.2 mol / L H2SO4 solution containing 2 mmol / L H2PtCl6 and 2 mmol / L KPdCl4 over a potential window of -0.4 V to +0.6 V at a scan rate of 50 mV / s for a specified number of cycles. After electrodeposition, the electrode was rinsed with copious amounts of deionized water and dried at room temperature. The modified Pt-Pd-GO / GCE electrode was then stored at room temperature.

[0037] During the preparation of Pt-Pd-GO modified electrodes, experiments were conducted on different GO modification volumes and scanning cycles and found that:

[0038] See also Figure 1 As shown in Figure 2, after modifying 5 μL, 7 μL, 8 μL, and 10 μL of graphene on the glassy carbon electrode, the cyclic voltammetry (CV) curves obtained by scanning in potassium ferricyanide solution (1 mmol / L) are as follows. Figure 1 As shown in A, and the bar graph of the current increase multiple, as shown in Figure 1 As shown in B; CV curves after 8, 12, 14, 16, and 18 cycles of chloroplatinic acid and potassium chloropalladate mixed solution (2 mmol / L) were electrodeposited on 8 μL of graphene modified on a glassy carbon electrode, as shown in Figure 1 As shown in C;

[0039] like Figure 1As shown in Figure A, the effect of different modified volumes of GO on the electrode on the current potential during the redox reaction in potassium ferricyanide solution was investigated. Graphene and chitosan (CS) were used in combination because GO does not have adhesion. CS can adsorb GO on the surface of the glassy carbon electrode to form a film with a huge specific surface area. The composite film can greatly improve the conductivity of the electrode. Compared with the bare electrode, the current increased significantly after GO modification. When the modified volume was 8 μL, the current increased the most, about 60 μA. The modification amount of Pd-PtNPs was controlled by changing the number of CV scans of its electrodeposition in a mixed solution of a given concentration (2 mmol / L); as shown in Figure 4. Figure 1 C shows that the current increase is the largest when the number of CV scans for electrodeposited Pd-Pt NPs is 16. Therefore, after comprehensive consideration, the optimal modification conditions were selected: 8 μL of modified GO and 16 cycles of electrodeposition in a mixed solution of potassium chloroplatinate and potassium chloropalladate.

[0040] See also Figure 2 As shown in the figure, a comparison was made between bare glassy carbon electrode (GCE), graphene modified electrode (GO / GCE), palladium-platinum nanoparticle modified electrode (Pd-Pt / GCE) and palladium-platinum-graphene nanocomposite modified electrode (Pd-Pt-GO / GCE).

[0041] CV curves of GCE, GO / GCE, Pd-Pt / GCE, and Pd-Pt-GO / GCE in solutions containing 1 mmol / L potassium ferrocyanide and 0.1 mol / L potassium chloride, as shown in Figure 2 As shown in A, the comparison chart of the bar graph of the current increase multiple is as follows Figure 2 As shown in B, scanning speed: 100 mV / s;

[0042] like Figure 2 Figure A shows the CV curves of bare glassy carbon electrode (GCE), graphene modified electrode (GO / GCE), palladium-platinum nanoparticle modified electrode (Pd-Pt / GCE) and palladium-platinum-graphene nanocomposite modified electrode (Pd-Pt-GO / GCE) in K3[Fe(CN)6] solution. Compared with the peak potential, the peak current of the modified electrodes GO / GCE, Pd-Pt / GCE and Pd-Pt-GO / GCE is significantly increased compared with the bare electrode (GCE); Figure 2 In Figure B, it can be seen that the peak current of Pd-Pt-GO / GCE is the largest. This is because the specific surface area and good electron conduction rate of graphene, as well as the increase in redox current after being decorated with palladium-platinum nanoparticles, can be calculated according to the Randles-Sevcik equation:

[0043] Ip = 2.69×10 5 AD 1 / 2n 3 / 2 γ 1 / 2 C

[0044] Where Ip represents the redox peak current value, in amperes; A represents the effective area of ​​the electrode, in cm 2 ; D represents the diffusion coefficient of molecules in the solution, which is (6.70 ± 0.02)×10 −6 cm 2 / s; n represents the number of electron transfers during redox, for [Fe(CN)6] 3- , n = 1; γ represents the scan rate of the cyclic voltammetry curve, in V / s; C represents the concentration of the redox probe molecule in the solution, in mol / cm 3 The effective areas of the four modified electrodes were calculated as GCE (0.06886 cm 2 )<GO / GCE(0.7954 cm 2 )<Pd / Pt / GCE(33.73 cm 2 )<Pd-Pt-GO / GCE(40.17 cm 2 ), which indicates that the specific surface area of ​​the modified electrode is significantly increased, especially for Pd-Pt-GO / GCE, which makes it possible to perform high-sensitivity detection on Pd-Pt-GO / GCE;

[0045] See also Figure 3 As shown, the electrocatalytic reduction performance of Pd-Pt-GO / GCE for hydrogen peroxide was further investigated by CV technology:

[0046] CV curves of Pd-Pt-GO / GCE in PBS solutions (0.01 mol / L, pH 7.4) with different concentrations of hydrogen peroxide. The hydrogen peroxide concentrations are: 0 mmol / L, 0.93 μmol / L, 7.5 μmol / L, 1 mmol / L, 0.02 mmol / L, 0.03 mmol / L, 0.06 mmol / L, 0.09 mmol / L, and 0.3 mmol / L; scan rate: 100 mV / s. Figure 3 As shown;

[0047] Figure 3The CV curves of Pd-Pt-GO / GCE sensor in deoxygenated PBS (0.01 mol / L, pH 7.2) before and after the addition of hydrogen peroxide are shown. Hydrogen peroxide is added successively, and when the concentration is 0.93 μmol / L, the reduction peak of hydrogen peroxide appears and moves to the negative potential direction with the increase of the concentration. With the increase of the concentration, the reduction peak current also increases, and the peak potential is concentrated near ±0.05 V. It is shown that hydrogen peroxide in the concentration range (0.93 μmol / L-0.3 mmol / L) can be catalytically reduced by Pd-Pt-GO / GCE. The excellent electrocatalytic reduction performance of Pd-Pt-GO / GCE to hydrogen peroxide is mainly due to the synergistic effect of the unique nanostructure of Pd-Pt-GO and the high specific surface area.

[0048] Please refer to Figure 4 It is shown that next, the optimal reduction potential of Pd-Pt-GO / GCE to hydrogen peroxide is determined, and the chronoamperometry (i-t) method is used to determine:

[0049] The i-t curves of Pd-Pt-GO / GCE for detecting H2O2 at potentials of 0.05 V, -0.05 V and -0.1 V are shown in Figure 4 A, and the corresponding fitting straight line graph is shown in Figure 4 B.

[0050] The detection sensitivity of several different modified electrodes to hydrogen peroxide is compared by amperometric current-time response (i-t) technology, so as to illustrate the superior performance of the constructed Pd-Pt-GO / GCE hydrogen peroxide sensor. First, according to the CV response curve of hydrogen peroxide in Figure 3 , three potentials of -0.1 V, -0.05 V and 0.05 V are selected, and the sensitivity of the i-t response curve of the modified electrode Pd-Pt-GO / GCE to hydrogen peroxide at the three potentials is measured, as shown in Figure 4 A, the response sensitivity of Pd-Pt-GO / GCE to hydrogen peroxide is the highest at -0.05 V, Figure 4 The concentration of hydrogen peroxide added dropwise at the three potentials is the same in the linear equation of B, so the response to hydrogen peroxide is better with higher slope, and the slopes of the three are: 0.63 (-0.05 V) > 0.55 (-0.1 V) > 0.51 (0.05 V), so -0.05 V is selected as the working potential of the hydrogen peroxide sensor.

[0051] Please refer to Figure 5 It is shown that next, the detection sensitivity of several different modified electrodes to hydrogen peroxide is compared by i-t technology, so as to illustrate the superior performance of the constructed Pd-Pt-GO / GCE sensor:

[0052] It curves of GCE, GO / GCE, Pd-Pt / GCE and Pd-Pt-GO / GCE obtained by continuous addition of H2O2 to deoxygenated PBS (0.01 mol / L, pH 7.2) solution, potential: -0.05 V; Figure 5 As shown;

[0053] The current responses of GCE, GO / GCE, Pd-Pt / GCE and Pd-Pt-GO / GCE modified electrodes were compared when hydrogen peroxide was continuously added into PBS (0.01 mol / L, pH 7.2) at an applied potential of -0.05 V. Figure 5 As shown in the figure, compared with GCE, GO / GCE and Pd-Pt / GCE, Pd-Pt-GO / GCE has a significantly higher response to the addition of the same hydrogen peroxide concentration. The excellent electrocatalytic activity of the Pd-Pt-GO modified electrode can be attributed to the good synergistic effect between palladium-platinum nanoparticles and graphene nanomaterials. On the one hand, GO has good conductivity and a large specific surface area, so as to fully utilize their catalytic properties. On the other hand, the palladium-platinum nanoparticles dispersed on GO provide better catalytic activity than single-component nanoparticles, indicating that Pd-Pt-GO / GCE is an excellent nanocomposite material for hydrogen peroxide detection.

[0054] See also Figure 6 As shown in Figure 2, the optimal modification conditions were determined: 8 μL GO and 16 cycles of deposited Pd-Pt NPs; the optimal reduction potential was -0.05 V. After that, different concentrations of hydrogen peroxide were continuously added to the deoxygenated PBS (0.02 mol / L, pH 7.4) solution, the it response curve of Pd-Pt-GO / GCE was obtained, potential: -0.05 V, as shown in Figure 2. Figure 6 As shown in A;

[0055] The linear calibration curve of the amperometric current and H2O2 concentration of Pd-Pt-GO / GCE in the range of hydrogen peroxide concentration from 31.2 nmol / L to 92.2 μmol / L is shown in Figure 2. Figure 6 As shown in B;

[0056] It is known that excessive GO drop-coating on a certain area of ​​modified surface will cause repeated accumulation of GO nanoparticles, which will reduce its specific surface area; if excessive Pd-Pt NPs are electrodeposited, they will stack on GO and cover GO; if too few Pd-Pt NPs are electrodeposited, the synergistic effect will be greatly reduced. After determining these conditions, the time-current response of the Pd-Pt-GO / GCE modified electrode to the continuous addition of hydrogen peroxide to PBS (0.01 mol / L, pH 7.2) at an applied potential of -0.05 V was obtained, as shown in Figure 2. Figure 6As shown in A. There are two linear ranges for the detection of hydrogen peroxide in the concentration range of 31.2 nmol / L to 92.2 μmol / L: 31.2×10 -9 ~9.71×10 -6 mol / L, Y=1.191X+3.915, linear correlation coefficient R 2 =0.988; 10.56×10 -6 ~92.2×10 -6 mol / L, Y=0.639X+7.416, linear correlation coefficient R 2 =0.972 Figure 6 Figure B shows the lowest detection limit of the hydrogen peroxide sensor, calculated at a signal-to-noise ratio of 3 (S / N=3), of approximately 31.2 nmol / L. Therefore, the prepared hydrogen peroxide sensor has a wide linear range, a low detection limit, and high sensitivity.

[0057] See also Figure 7 As shown, further experiments were conducted on the anti-interference ability of the Pt-Pd-GO / GCE sensor, and the following results were obtained:

[0058] The it curve of the anti-interference ability of Pd-Pt-GO was investigated. 50 mmol / L H2O2, 50 mmol / L glycine (Gly), 50 mmol / L glucose (Glu), 50 mmol / L glutathione (Gsh), 50 mmol / L ascorbic acid (AA) and 50 mmol / L H2O2 were added to the deoxygenated PBS (0.02 mol / L, pH = 7.4) solution successively; the potential was -0.05 V. Figure 7 As shown;

[0059] For electrochemical sensors, the key to preventing other electroactive substances from interfering with the sample to be detected is to select a suitable detection potential to avoid the redox reaction of the interfering substances at this potential. In addition, the constructed sensor uses the electrochemical reduction current of hydrogen peroxide for detection, and is further used to detect H2O2 released by cells. Therefore, it is necessary to consider the redox reaction potential of electroactive molecules such as glycine (Gly), glucose (Glu), glutathione (Gsh), and ascorbic acid (AA) that may exist in the biological system. -0.05 V was selected as the working potential. At this potential, the above-mentioned electroactive interfering substances are not sufficient to undergo redox reactions, and the interference of dissolved oxygen can be removed by passing high-purity nitrogen gas into the solution. Figure 7As shown, when 0.5 mol / L H₂O₂ was added, the current increased rapidly and reached a stable value. Subsequently, no significant current response was observed when 50 mmol / L Gly, 50 mmol / L Glu, 50 mmol / L Gsh, and 50 mmol / L AA were added. However, the same current response was observed after the addition of 0.5 mol / L H₂O₂. Therefore, the constructed electrode modified with the Pd-Pt-GO nanocomposite exhibits excellent selectivity and is not affected by interference from electroactive species in biological systems. This demonstrates that the prepared hydrogen peroxide sensor has potential application prospects and practical value.

[0060] Pt-Pd NPs were deposited onto the GO-modified electrode surface by electrochemical deposition to prepare a Pt-Pd-GO nanocomposite enzyme-mimicking electrochemical sensor; the sensor has a wide detection range, low detection limit and anti-interference ability in hydrogen peroxide detection.

[0061] This method was used to fabricate a high-performance novel electrochemical hydrogen peroxide sensor. Through the synergistic effect of several nanomaterials, the prepared Pt-Pd-GO / GCE enzyme-free sensor exhibited a wide detection range (31.2 nmol / L–92.2 μmol / L), a low detection limit (31.2 nmol / L), and excellent anti-interference capabilities.

[0062] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A method for preparing a hydrogen peroxide electrochemical sensor, characterized in that: Here are the steps: S1. Preparation of GO dispersion: Graphene with a volume concentration of 2 mg / mL was ultrasonically mixed in ultrapure water, and then ultrasonically mixed with chitosan solution with a mass fraction of 1% at a volume ratio of 5:1; S2, preparation of Pt-Pd NPs electrodeposition solution: 2 mmol / L chloroplatinic acid solution and 2 mmol / L potassium chloropalladate solution were mixed with 0.2 mol / L H2SO4; S3, GCE pretreatment, 0.3 μm and 0.05 μm aluminum oxide powder were used to polish the suede until the surface became mirror smooth, and then washed with ultrapure water for 5 minutes; S4. Prepare GO / GCE modified electrodes. After drying the GCE with N2 gas flow, immediately add GO dispersion droplets to the electrode surface and dry at room temperature for three hours to obtain the GO / GCE modified electrode. Before use, it is necessary to repeat the soaking and drying with distilled water twice to remove the unfixed nanomaterials on the surface of the GO / GCE modified electrode. S5. Electrodeposition of Pt-Pd NPs onto the GO / GCE modified electrode. Electrodeposition of Pt-Pd NPs was performed by scanning a certain number of cycles in a 0.2 mol / L H2SO4 solution containing 2 mmol / L H2PtCl6 and 2 mmol / L KPdCl4. The potential window was -0.4 V to +0.6 V, and the scanning rate was 50 mV / s.

2. The method for preparing a hydrogen peroxide electrochemical sensor according to claim 1, wherein: There is also step S6, after the electrodeposition is completed, the electrode is washed with a large amount of deionized water and dried at room temperature. After the modified electrode Pt-Pd-GO / GCE is prepared, it is stored at room temperature.

3. The method for preparing a hydrogen peroxide electrochemical sensor according to claim 2, wherein: The modified volume of the GO dispersion is 2 μL~10 μL.

4. The method for preparing a hydrogen peroxide electrochemical sensor according to claim 3, wherein: The number of scanning circles is 8 to 18 circles.

5. The method for preparing a hydrogen peroxide electrochemical sensor according to claim 4, characterized in that: The volume of the GO dispersion was 8 μL, and the number of scanning cycles was 16 cycles of electrodeposition.

6. The method for preparing a hydrogen peroxide electrochemical sensor according to claim 5, characterized in that: The working potential of the hydrogen oxide electrochemical sensor is -0.05 V.

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