Electrochemical sensor working electrode and preparation method and application thereof

Abstract

The invention discloses an electrochemical sensor working electrode and a preparation method and application thereof, and belongs to the technical field of electrochemical sensing. Firstly, organic semiconductor micromolecules (PTCK) are prepared as organic ligands, then the organic semiconductor micromolecules, chloroplatinic acid and few layers of graphene oxide are prepared into a PTCK-Pt-GO compound through a hydrothermal method, and then the graphene composite film (P-Pt-G) loaded with platinum nanoparticles is prepared on the surface of a working electrode area through in-situ electrochemical reduction. According to the functionalized graphene composite film prepared through electrochemical reduction, platinum nanoparticles are uniformly dispersed, more catalytic sites can be exposed, the detection capacity of hydrogen peroxide is improved, and the functionalized graphene composite film can be applied to preparation of a high-sensitivity hydrogen peroxide electrochemical sensor. The preparation process provided by the invention is simple, and the sensor has relatively low detection line and good detection performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrochemical sensing, and particularly relates to a working electrode of an electrochemical sensor for detecting hydrogen peroxide and a preparation method and application thereof. BACKGROUND

[0002] Hydrogen peroxide (H2O2), commonly known as hydrogen peroxide, is widely used as a disinfectant, bactericide and bleaching agent in many fields such as food production, clinical medicine, ecology, mining, textile and papermaking due to its strong oxidizing property. In addition, H2O2 is an important signal molecule in the body, which plays an important role in biological cell signal transmission, biological defense and sterilization, wound detection and repair, and is also the initiator of a series of pathological and physiological cascade reactions, leading to cell death or adaptive changes, and has an important influence on cell function and metabolism; therefore, the detection of H2O2 is of great significance for the early diagnosis of some diseases and the monitoring of the treatment process.

[0003] So far, there are various analysis methods for detecting H2O2, among which the electrochemical sensor is a simple, inexpensive and linear detection range wide, low detection limit, fast, sensitive and other characteristics of the method, which is widely used in food, medicine and environmental safety and other fields, and satisfactory results have been achieved. For example, the patent for invention with publication number CN115711925A discloses a preparation method of a hydrogen peroxide electrochemical sensor, which 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 through the synergistic effect of several nanomaterials. However, the core material of this scheme is Pt-Pd alloy nanoparticles, which excessively relies on noble metals, greatly increasing the manufacturing cost of the sensor, and the preparation process is complex and the reproducibility is poor. The existing electrochemical detection method still has the following problems: on the one hand, its sensitivity and selectivity are often difficult to balance, and it is easy to be disturbed by other electroactive substances in complex actual samples, resulting in a decrease in the reliability of the detection results; on the other hand, the preparation process of high-performance sensors is usually complex, or relies on expensive rare materials, which restricts its large-scale production and popular application.

[0004] Therefore, it is a key problem to be solved in this technical field to develop a new type of hydrogen peroxide electrochemical sensor with high sensitivity, high selectivity, excellent stability and low preparation cost, which also has significant practical application value. SUMMARY

[0005] In order to solve the problems of low selectivity, low sensitivity and complex preparation process of the existing hydrogen peroxide electrochemical detection method, the application provides an electrochemical sensor, a preparation method and application thereof, overcomes the defects of the prior art, and realizes efficient and accurate hydrogen peroxide detection.

[0006] In order to achieve the above-mentioned purpose, the technical scheme of the application is as follows: The application provides a preparation method of an electrochemical sensor working electrode, and the specific steps are as follows: (1) Synthesis of PTCK 3, 4, 9, 10-perylenetetracarboxylic dianhydride is added into a potassium hydroxide solution to react, and after filtration, it is dissolved in deionized water again, washed after recrystallization to obtain PTCK, and the molecular formula is as follows: (2) Preparation of PTCK-Pt-GO composite The PTCK obtained in step (1) is added into a graphene oxide aqueous solution containing chloroplatinic acid, and hydrothermal reaction is carried out by stirring, and after drying and water washing and drying, a PTCK-Pt-GO composite is obtained; (3) Preparation of graphene composite film (P-Pt-G) The PTCK-Pt-GO composite aqueous solution is dropped and coated on the surface of the working electrode, and after drying, the electrode sheet is inserted into a PBS buffer solution to carry out in-situ electrochemical reduction, and after reduction, water washing and drying are carried out, and a P-Pt-G composite film is prepared on the surface of the working electrode, so that the electrochemical sensor working electrode is obtained.

[0007] In step (1), the molar ratio of 3, 4, 9, 10-perylenetetracarboxylic dianhydride to potassium hydroxide is 1:5-10, the concentration of the potassium hydroxide solution is 0.2-0.4 M, and the reaction temperature is 80-95 DEG C.

[0008] In step (2), the mass ratio of PTCK, chloroplatinic acid and graphene oxide is 1:1-3:2-10, the concentration of graphene oxide in the graphene oxide aqueous solution is 0.5-1 mg / mL, and the concentration of chloroplatinic acid is 0.5-2 mM; the temperature of the hydrothermal reaction is 25-50 DEG C, and the time is 10-30 h.

[0009] In step (3), the concentration of the PTCK-Pt-GO composite aqueous solution is 0.1-1.2 mg / mL, and the concentration of the PBS buffer solution is 0.1-0.5 M; the in-situ electrochemical reduction adopts a cyclic voltammetry method, and the reduction voltage is-1.4 V-0.7 V.

[0010] The present invention also provides an electrochemical sensor, comprising a counter electrode, a reference electrode, and an electrochemical sensor working electrode prepared by the above preparation method. The sensitive region of the working electrode is modified with a graphene composite film loaded with platinum nanoparticles. The platinum nanoparticles are uniformly dispersed in the graphene composite film, and the average particle size of the platinum nanoparticles is 2-4 nm.

[0011] The present invention also provides the application of the electrochemical sensor described herein in the detection of hydrogen peroxide.

[0012] The present invention has the following beneficial effects: (1) The present invention reduces the electrode material on the surface of the electrode in situ by in situ electrochemical reduction. The preparation method is simple and can make the electrode material firmly contact the electrode, effectively preventing the electrode material from falling off and causing a weakening of the electrochemical sensor performance.

[0013] (2) By introducing the organic small molecule PTCK and platinum ion complex in situ on the surface of graphene oxide, more platinum ions can be loaded more firmly on the graphene surface. At the same time, the large conjugated structure of PTCK can promote electron transfer, which is beneficial to the improvement of sensor performance.

[0014] (3) The P-Pt-G composite film obtained by in-situ electrochemical reduction during electrode preparation can be used as the electrode material for the working electrode. This can fully utilize the electron transport capability of graphene. Furthermore, the in-situ reduction process can prevent the aggregation of platinum nanoparticles due to the confinement effect of the organic small molecule PTCK, thus exposing more active sites. This facilitates the preparation of a high-performance hydrogen peroxide sensor with a detection sensitivity of up to 495.235 μA cm⁻¹. -2 mM -1 The detection limit is as low as 1 μM. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 The infrared spectrum (left) of PTCK prepared in Example 1 and the ultraviolet-fluorescence spectrum (right) of PTCK aqueous solution.

[0017] Figure 2 SEM (left) and TEM (right) images of the P-Pt-G composite film prepared in Example 1.

[0018] Figure 3 This is a schematic diagram of the electrode sheet in Example 1.

[0019] Figure 4 The image shows a TEM image of the P-Pt-G composite film prepared in Example 2.

[0020] Figure 5 Here is the molecular formula of PTCH in Comparative Example 1.

[0021] Figure 6 The electrochemical sensor prepared in Example 1 responds to different concentrations of hydrogen peroxide with current diagrams.

[0022] Figure 7 The response current diagram of the electrochemical sensor prepared in Example 2 to different concentrations of hydrogen peroxide. Figure 8 The response current diagram of the electrochemical sensor prepared in Example 3 to different concentrations of hydrogen peroxide. Figure 9 The electrochemical sensor prepared for Comparative Example 1 shows the response current diagrams to different concentrations of hydrogen peroxide.

[0023] Figure 10 The electrochemical sensor prepared for Comparative Example 2 shows the response current diagrams of different concentrations of hydrogen peroxide. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Unless otherwise specified, the experimental methods used in the following experimental examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0026] Example 1 A method for preparing an electrochemical sensor, the specific steps of which are as follows: (1) Synthesis of PTCK 1.17 g of 3,4,9,10-perylenetetracarboxylic acid dianhydride was added to 50 mL of 0.3 M potassium hydroxide solution, stirred until homogeneous, reacted at 80 °C for 10 hours, and then cooled to obtain a bright yellow solution. 200 mL of anhydrous ethanol was added and stirred to precipitate the precipitate. The precipitate was filtered and dried to obtain solid powder PTCK. The molecular formula of PTCK is .

[0027] The UV-fluorescence and infrared spectra of PTCK aqueous solution are as follows: Figure 1 As shown, in the infrared spectrum, 1593 cm⁻¹ -1 The peak at 1412 cm⁻¹ is attributed to the C=C stretching vibration on the benzene ring. -1 The vibration is attributed to the symmetric stretching vibration of the carboxylate group, 1552 cm. -1 The peaks are attributed to the antisymmetric stretching vibration of the carboxyl group. Absorption peaks are observed at 412 nm, 438 nm, and 466 nm in the UV absorption spectrum, indicating that PTCK molecules do not aggregate in aqueous solution.

[0028] (2) Preparation of PTCK-Pt-GO complex Prepare a 1 mg / mL aqueous solution of few-layer graphene oxide containing 1 mM chloroplatinic acid. Take 5 mL of the graphene oxide and chloroplatinic acid mixture and add 1.25 mg of PTCK. After stirring evenly, heat the mixture at 35 °C for 24 hours. After the reaction is complete, freeze-dry to obtain a solid. Wash the solid with water and dry to obtain the PTCK-Pt-GO complex. (3) Preparation of graphene composite film (P-Pt-G) First, the PTCK-Pt-GO composite was sonicated at room temperature for 1 h to prepare a homogeneous aqueous solution of 0.5 mg / mL. Then, the working electrode area on the electrode sheet was washed with water and cleaned with ethanol. The electrode was then activated in 0.1 M H2SO4 solution at -0.8 V to 0.8 V for later use. Next, 5 μL of the homogeneous aqueous solution of the PTCK-Pt-GO composite was drop-coated onto the surface of the working electrode area on the electrode sheet. After drying, the electrode sheet was immersed in 0.1 M PBS buffer solution for in-situ cyclic voltammetric electrochemical reduction. The reduction voltage was between -1.4 V and 0.7 V. After reduction, the electrode sheet was washed with water and dried. A P-Pt-G composite film was prepared on the surface of the working electrode area on the electrode sheet, which is the working electrode of the electrochemical sensor.

[0029] The prepared P-Pt-G composite film was characterized by SEM and TEM, and the results are as follows: Figure 2 As shown, the platinum nanoparticles have an average size of 2.71 nm and are uniformly distributed. The graphene retains its sheet-like structure and has a wrinkled surface.

[0030] Electrochemical sensors consist of electrode plates, as shown in the schematic diagram below. Figure 3 As shown, the electrode sheet includes a substrate, wires, a reference electrode (micro solid Ag / AgCl electrode), a counter electrode (graphite electrode), a working electrode prepared in this embodiment, and a portable electrochemical workstation. The electrode sheet can be directly inserted into the port of the portable electrochemical workstation for connection, and the measurement can be achieved by placing the other end of the electrode sheet into the test solution.

[0031] Example 2 A method for preparing an electrochemical sensor, the specific steps of which are as follows: (1) Synthesis of PTCK 1.17 g of 3,4,9,10-perylenetetracarboxylic acid dianhydride was added to 50 mL of 0.3 M potassium hydroxide solution, stirred until homogeneous, reacted at 80 °C for 10 hours, and then cooled to obtain a bright yellow solution. 200 mL of anhydrous ethanol was added and stirred to precipitate the precipitate. The precipitate was filtered and dried to obtain solid powder PTCK. (2) Preparation of PTCK-Pt-GO complex Prepare a 1 mg / mL aqueous solution of few-layer graphene oxide containing 1.5 mM chloroplatinic acid. Take 5 mL of the graphene oxide and chloroplatinic acid mixture and add 1.25 mg PTCK. After stirring evenly, heat at 35 °C for 24 hours. After the reaction is complete, freeze dry to obtain a solid. Wash the solid with water and dry to obtain the PTCK-Pt-GO complex. (3) Preparation of graphene composite film (P-Pt-G) The PTCK-Pt-GO composite was sonicated at room temperature for 1 h to prepare a homogeneous aqueous solution of 0.5 mg / mL. The working electrode area on the electrode sheet was washed with water and cleaned with ethanol. The electrode was then activated in 0.1 M H2SO4 solution at -0.8 V to 0.8 V for later use. 5 μL of the homogeneous aqueous solution of the PTCK-Pt-GO composite was drop-coated onto the surface of the working electrode area on the electrode sheet. After drying, the electrode sheet was immersed in 0.1 M PBS buffer solution for in-situ cyclic voltammetric electrochemical reduction. The reduction voltage was between -1.4 V and 0.7 V. After reduction, the electrode sheet was washed with water and dried. A P-Pt-G composite film was prepared on the surface of the working electrode area on the electrode sheet, which is the working electrode of the electrochemical sensor.

[0032] The prepared P-Pt-G composite film was characterized by TEM, and the results are as follows: Figure 4 As shown, the average particle size of platinum nanoparticles in the electrochemical sensor working electrode material obtained in this embodiment is 4.93 nm.

[0033] The electrochemical sensor consists of an electrode sheet, which includes a substrate, wires, a reference electrode (a miniature solid-state Ag / AgCl electrode), a counter electrode (a graphite electrode), a working electrode prepared in this embodiment, and a portable electrochemical workstation. The electrode sheet can be directly inserted into the port of the portable electrochemical workstation for connection, and the measurement can be achieved by placing the other end of the electrode sheet into the test solution.

[0034] Example 3 A method for preparing an electrochemical sensor, the specific steps of which are as follows: (1) Synthesis of PTCK 1.17 g of 3,4,9,10-perylenetetracarboxylic acid dianhydride was added to 50 mL of 0.3 M potassium hydroxide solution, stirred until homogeneous, reacted at 80 °C for 10 hours, and then cooled to obtain a bright yellow solution. 200 mL of anhydrous ethanol was added and stirred to precipitate the precipitate. The precipitate was filtered and dried to obtain solid powder PTCK. (2) Preparation of PTCK-Pt-GO complex Prepare a 1 mg / mL aqueous solution of few-layer graphene oxide containing 0.5 mM chloroplatinic acid. Take 5 mL of the graphene oxide and chloroplatinic acid mixture and add 1.25 mg PTCK. After stirring evenly, heat at 35 °C for 24 hours. After the reaction is complete, freeze dry to obtain a solid. Wash the solid with water and dry to obtain the PTCK-Pt-GO complex. (3) Preparation of graphene composite film (P-Pt-G) The PTCK-Pt-GO composite was sonicated at room temperature for 1 h to prepare a homogeneous aqueous solution of 0.5 mg / mL. The working electrode area on the electrode sheet was washed with water and cleaned with ethanol. The electrode was then activated in 0.1 M H2SO4 solution at -0.8 V to 0.8 V for later use. 5 μL of the homogeneous aqueous solution of the PTCK-Pt-GO composite was drop-coated onto the surface of the working electrode area on the electrode sheet. After drying, the electrode sheet was immersed in 0.1 M PBS buffer solution for in-situ cyclic voltammetric electrochemical reduction. The reduction voltage was between -1.4 V and 0.7 V. After reduction, the electrode sheet was washed with water and dried. A P-Pt-G composite film was prepared on the surface of the working electrode area on the electrode sheet, which is the working electrode of the electrochemical sensor.

[0035] The electrochemical sensor consists of an electrode sheet, which includes a substrate, wires, a reference electrode (a miniature solid-state Ag / AgCl electrode), a counter electrode (a graphite electrode), a working electrode prepared in this embodiment, and a portable electrochemical workstation. The electrode sheet can be directly inserted into the port of the portable electrochemical workstation for connection, and the measurement can be achieved by placing the other end of the electrode sheet into the test solution.

[0036] Example 4 A method for preparing an electrochemical sensor, the specific steps of which are as follows: (1) Synthesis of PTCK 1.12 g of 3,4,9,10-perylenetetracarboxylic acid dianhydride was added to 50 mL of 0.4 M potassium hydroxide solution, stirred until homogeneous, reacted at 90 °C for 10 hours, and then cooled to obtain a bright yellow solution. 200 mL of anhydrous ethanol was added and stirred to precipitate the precipitate. The precipitate was filtered and dried to obtain solid powder PTCK. (2) Preparation of PTCK-Pt-GO complex Prepare a 0.55 mg / mL aqueous solution of few-layer graphene oxide containing 2 mM chloroplatinic acid. Take 5 mL of the graphene oxide and chloroplatinic acid mixture and add 1.37 mg of PTCK. After stirring evenly, heat the mixture at 50 °C for 10 hours. After the reaction is complete, freeze-dry to obtain a solid. Wash the solid with water and dry to obtain the PTCK-Pt-GO complex. (3) Preparation of graphene composite film (P-Pt-G) The PTCK-Pt-GO composite was sonicated at room temperature for 1 h to prepare a homogeneous aqueous solution of 0.1 mg / mL. The working electrode area on the electrode sheet was washed with water and cleaned with ethanol. The electrode was then activated in 0.1 M H2SO4 solution at -0.8 V to 0.8 V for later use. 7 μL of the homogeneous aqueous solution of the PTCK-Pt-GO composite was drop-coated onto the surface of the working electrode area on the electrode sheet. After drying, the electrode sheet was immersed in 0.1 M PBS buffer solution for in-situ cyclic voltammetric electrochemical reduction. The reduction voltage was between -1.4 V and 0.7 V. After reduction, the electrode sheet was washed with water and dried. A P-Pt-G composite film was prepared on the surface of the working electrode area on the electrode sheet, which is the working electrode of the electrochemical sensor.

[0037] The electrochemical sensor consists of an electrode sheet, which includes a substrate, wires, a reference electrode (a miniature solid-state Ag / AgCl electrode), a counter electrode (a graphite electrode), a working electrode prepared in this embodiment, and a portable electrochemical workstation. The electrode sheet can be directly inserted into the port of the portable electrochemical workstation for connection, and the measurement can be achieved by placing the other end of the electrode sheet into the test solution.

[0038] Example 5 A method for preparing an electrochemical sensor, the specific steps of which are as follows: (1) Synthesis of PTCK 392.3 mg of 3,4,9,10-perylenetetracarboxylic acid dianhydride was added to 50 mL of 0.2 M potassium hydroxide solution, stirred until homogeneous, reacted at 95 °C for 10 hours, and then cooled to obtain a bright yellow solution. 200 mL of anhydrous ethanol was added and stirred to precipitate the precipitate. The precipitate was filtered and dried to obtain solid powder PTCK. (2) Preparation of PTCK-Pt-GO complex Prepare a 1 mg / mL aqueous solution of few-layer graphene oxide containing 0.5 mM chloroplatinic acid. Take 5 mL of the graphene oxide and chloroplatinic acid mixture and add mg PTCK. After stirring evenly, heat at 25 °C for 30 hours. After the reaction is complete, freeze dry to obtain a solid. Wash the solid with water and dry to obtain the PTCK-Pt-GO complex. (3) Preparation of graphene composite film (P-Pt-G) The PTCK-Pt-GO composite was sonicated at room temperature for 1 h to prepare a homogeneous aqueous solution of 1.2 mg / mL. The working electrode area on the electrode sheet was washed with water and cleaned with ethanol. The electrode was then activated in 0.1 M H2SO4 solution at -0.8 V to 0.8 V for later use. 3 μL of the homogeneous aqueous solution of the PTCK-Pt-GO composite was drop-coated onto the surface of the working electrode area on the electrode sheet. After drying, the electrode sheet was immersed in 0.5 M PBS buffer solution for in-situ cyclic voltammetric electrochemical reduction. The reduction voltage was between -1.4 V and 0.7 V. After reduction, the electrode sheet was washed with water and dried. A P-Pt-G composite film was prepared on the surface of the working electrode area on the electrode sheet, which is the working electrode of the electrochemical sensor.

[0039] The electrochemical sensor consists of an electrode sheet, which includes a substrate, wires, a reference electrode (a miniature solid-state Ag / AgCl electrode), a counter electrode (a graphite electrode), a working electrode prepared in this embodiment, and a portable electrochemical workstation. The electrode sheet can be directly inserted into the port of the portable electrochemical workstation for connection, and the measurement can be achieved by placing the other end of the electrode sheet into the test solution.

[0040] Comparative Example 1 (1) Preparation of PTCH-Pt-GO complex Prepare a 1 mg / mL aqueous solution of few-layer graphene oxide containing 1 mM chloroplatinic acid. Take 5 mL of the graphene oxide and chloroplatinic acid mixture and add 1.25 mg of perylenetetracarboxylic acid (PTCH, molecular formula as shown). Figure 8 As shown in the figure, after stirring evenly, the mixture was heated at 35°C for 24 hours. After the reaction was completed, the solid was freeze-dried to obtain a solid. The solid was then washed with water and dried to obtain the PTCH-Pt-GO complex. (2) Preparation of graphene composite film (P-Pt-G) A homogeneous aqueous solution of PTCH-Pt-GO composite was prepared by sonication at room temperature for 1 h to a concentration of 0.5 mg / mL. The working electrode area on the electrode sheet was washed with water and cleaned with ethanol. The electrode was then activated in 0.1 M H₂SO₄ solution at -0.8 V to 0.8 V for later use. 5 μL of the homogeneous aqueous solution of PTCH-Pt-GO composite was drop-coated onto the working electrode area of ​​the electrode sheet. After drying, the electrode sheet was immersed in 0.1 M PBS buffer solution for in-situ cyclic voltammetric electrochemical reduction. The reduction voltage was between -1.4 V and 0.7 V. After reduction, the electrode sheet was washed with water and dried. A PH-Pt-G composite film was prepared on the working electrode area of ​​the electrode sheet, thus obtaining the working electrode of the electrochemical sensor.

[0041] The electrochemical sensor consists of an electrode sheet, which includes a substrate, wires, a reference electrode (a miniature solid-state Ag / AgCl electrode), a counter electrode (a graphite electrode), a working electrode prepared in this embodiment, and a portable electrochemical workstation. The electrode sheet can be directly inserted into the port of the portable electrochemical workstation for connection, and the measurement can be achieved by placing the other end of the electrode sheet into the test solution.

[0042] Comparative Example 2 (1) Preparation of Pt-GO complex Prepare a 1 mg / mL aqueous solution of few-layer graphene oxide containing 1 mM chloroplatinic acid. Take 5 mL of the graphene oxide and chloroplatinic acid mixture, stir it evenly, and heat it at 35 °C for 24 hours. After the reaction is completed, freeze-dry to obtain a solid. Wash the solid with water and dry it to obtain the Pt-GO complex. (2) Preparation of graphene composite film (Pt-G) A homogeneous aqueous solution of Pt-GO composite was prepared by sonication at room temperature for 1 h to a concentration of 0.5 mg / mL. The working electrode area on the electrode sheet was washed with water and ethanol, and then activated in 0.1 M H₂SO₄ solution at -0.8 V to 0.8 V for later use. 5 μL of the homogeneous aqueous solution of Pt-GO composite was drop-coated onto the working electrode area of ​​the electrode sheet. After drying, the electrode sheet was immersed in 0.1 M PBS buffer solution for in-situ cyclic voltammetric electrochemical reduction at a voltage between -1.4 V and 0.7 V. After reduction, the electrode sheet was washed with water and dried, thus preparing a Pt-G composite film on the working electrode area of ​​the electrode sheet, which is the working electrode of the electrochemical sensor.

[0043] The electrochemical sensor consists of an electrode sheet, which includes a substrate, wires, a reference electrode (a miniature solid-state Ag / AgCl electrode), a counter electrode (a graphite electrode), a working electrode prepared in this embodiment, and a portable electrochemical workstation. The electrode sheet can be directly inserted into the port of the portable electrochemical workstation for connection, and the measurement can be achieved by placing the other end of the electrode sheet into the test solution.

[0044] Implementation Results Example The hydrogen peroxide detection performance of the electrochemical sensors prepared in Examples 1-3 and Comparative Examples 1-2 was tested, as follows: The response current of the electrochemical sensor prepared in Example 1 to different concentrations of hydrogen peroxide is as follows: Figure 6 As shown, this sensor has a high sensitivity of 495.23 μA cm⁻¹. -2 mM -1 The minimum detection limit reaches 1 μM, and the sensor has a good linear relationship in the range of 1 μM-1 mM.

[0045] The response current of the electrochemical sensor prepared in Example 2 to different concentrations of hydrogen peroxide is as follows: Figure 7 As shown, the sensor's sensitivity is 334.13 μA cm⁻¹. -2 mM -1 The performance of the electrochemical sensor in Example 1 is somewhat worse, possibly due to the aggregation of platinum nanoparticles on the surface, which limits the exposure of catalytic sites.

[0046] The response current of the electrochemical sensor prepared in Example 3 to different concentrations of hydrogen peroxide is as follows: Figure 8 As shown, the sensitivity of the electrochemical sensor prepared in this embodiment is 287.66 μA cm⁻¹. -2 mM -1 The performance of the electrochemical sensor prepared in Example 1 is worse than that of the sensor prepared in Example 1, possibly due to the smaller number of fixed platinum ions, which leads to poor catalytic performance.

[0047] The electrochemical sensor prepared in Comparative Example 1 responded to different concentrations of hydrogen peroxide with the following currents: Figure 9 As shown, this electrochemical sensor has a sensitivity of 218.94 μA cm⁻¹. -2 mM -1 The performance of the sensor was not as good as that of the electrochemical sensor prepared in Example 1, indicating that the use of PTCK is more conducive to improving the performance of the sensor than PTCH.

[0048] The response current of the electrochemical sensor prepared in Comparative Example 2 to different concentrations of hydrogen peroxide is as follows: Figure 10 As shown, this electrochemical sensor has a sensitivity of 6.76 μA cm⁻¹. -2 mM -1 The performance of the sensor was not as good as that of the electrochemical sensor prepared in Example 1, indicating that the use of PTCK can help improve the performance of the sensor.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a working electrode for an electrochemical sensor, characterized in that, The specific steps are as follows: (1) 3,4,9,10-perylenetetracarboxylic acid dianhydride was added to potassium hydroxide solution for reaction, filtered, and then dissolved again in deionized water. After recrystallization and washing, PTCK was obtained. (2) The PTCK obtained in step (1) is added to an aqueous solution of graphene oxide containing chloroplatinic acid, stirred and subjected to hydrothermal reaction, dried, and then washed and dried to obtain the PTCK-Pt-GO complex. (3) Take the PTCK-Pt-GO composite aqueous solution and drop it onto the surface of the working electrode. After drying, insert the electrode sheet into the PBS buffer solution for in-situ electrochemical reduction. After reduction, wash with water and dry to prepare a P-Pt-G composite film on the surface of the working electrode, thus obtaining the working electrode of the electrochemical sensor.

2. The method for preparing the working electrode of the electrochemical sensor according to claim 1, characterized in that: In step (1), the molar ratio of 3,4,9,10-perylenetetracarboxylic acid dianhydride to potassium hydroxide is 1:5-10, the concentration of the potassium hydroxide solution is 0.2-0.4 mol / L, and the reaction temperature is 80-95℃.

3. The method for preparing the working electrode of the electrochemical sensor according to claim 2, characterized in that: In step (2), the mass ratio of PTCK, chloroplatinic acid and graphene oxide is 1:0.8-3:2-5, the concentration of graphene oxide in the aqueous solution is 0.55-1 mg / mL, and the concentration of chloroplatinic acid is 0.5-2 mM.

4. The method for preparing the working electrode of the electrochemical sensor according to claim 3, characterized in that: The hydrothermal reaction in step (2) is carried out at a temperature of 25-50°C for 10-30 hours.

5. The method for preparing the working electrode of the electrochemical sensor according to claim 4, characterized in that: In step (3), the concentration of the PTCK-Pt-GO complex aqueous solution is 0.1-1.2 mg / mL, and the concentration of the PBS buffer solution is 0.1-0.5M.

6. The method for preparing the working electrode of the electrochemical sensor according to claim 5, characterized in that: In step (3), the in-situ electrochemical reduction adopts the cyclic voltammetry method, and the reduction voltage is -1.4 V to 0.7 V.

7. The working electrode of the electrochemical sensor prepared by the preparation method according to any one of claims 1-6.

8. An electrochemical sensor, comprising a counter electrode, a reference electrode, and the electrochemical sensor working electrode of claim 7.

9. The electrochemical sensor according to claim 8, characterized in that: The sensitive region of the working electrode is modified with a graphene composite film loaded with platinum nanoparticles, which are uniformly dispersed in the graphene composite film.

10. The electrochemical sensor according to claim 9, characterized in that: The average particle size of the platinum nanoparticles is 2-4 nm.

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