Preparation method and application of polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride reference electrode

Abstract

The present invention belongs to the field of electrochemistry, specifically a preparation method and application of a polyvinyl alcohol hydrogel-foam carbon-silver / silver chloride reference electrode. The present invention uses foam carbon as the substrate of the reference electrode for the first time, electrochemically deposits and chlorinates the foam carbon to prepare a foam carbon-silver / silver chloride reference electrode with a rod-like structure, and then pours the polyvinyl alcohol hydrogel on the chlorinated electrode surface to obtain a polyvinyl alcohol hydrogel-foam carbon-silver / silver chloride reference electrode with good ion permeability, good conductivity and stable potential. The present invention can significantly improve the conductivity and stability of the electrode, and the stability of this reference electrode is comparable to that of a commercial reference electrode. The electrode prepared by the present invention is applied to the electrochemical detection of epinephrine, and its detection signal is significantly higher than that of a commercial reference electrode, and has good application prospects.

Description

Technical Field

[0001] The present invention relates to the field of electrochemical technology, and in particular to a preparation method and application of a polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride reference electrode. Background Art

[0002] In electrochemical research, the three-electrode system has attracted much attention. The three-electrode system includes a working electrode, an auxiliary electrode, and a reference electrode. The working electrode is the electrode that can detect significant changes in the concentration of the component being measured during the test. The auxiliary electrode, also known as the counter electrode, forms a current path throughout the test, providing a stable current for the circuit. The reference electrode is an electrode used as a reference for comparison when measuring various electrode potentials, and its function is to provide a stable electrode potential for the measurement process. When the working electrode detects the concentration of a component, only by providing a stable potential for the entire circuit can the measurement result be more accurately obtained. Therefore, the attention paid to reference electrodes has shown an upward trend in recent years.

[0003] At present, the preparation of sensors is developing in the direction of being comfortable, portable and having good detection effects. However, the common commercial silver / silver chloride reference electrodes are often made of rigid materials, which greatly limits their application range. Therefore, it is very important to prepare soft and comfortable silver / silver chloride reference electrodes. The traditional reference electrode is made of AgNO3, NaCl and Na2S as raw materials. The electrode composed of AgCl-Ag2S electrode membrane, polyvinyl chloride tube and wire cannot meet the market demand. Therefore, it is very important to use various new materials to prepare reference electrodes. For example, Tang Zilong et al. [1] Silver chloride was prepared from silver nitrate and hydrochloric acid, mixed with silver powder, pressed into a cylindrical shape, and then welded with wires, polished, and activated to prepare a bare Ag / AgCl solid reference electrode. [2] People use nanosilver ink inkjet printing to prepare silver / silver chloride reference electrodes. It uses glass, polyethylene terephthalate, and polyvinyl chloride as substrates, prints nanosilver onto the substrates by inkjet printing, and then uses electroplating to prepare silver / silver chloride electrodes. However, this electrode has problems such as poor conductivity and insufficient softness.

[0004] When studying flexible silver / silver chloride reference electrodes, scholars in this field have also made innovations in the performance, stability and conductivity of reference electrodes. For example, Liu Ruili et al. [3] Flexible fiber PVB was used as the substrate, and silver / silver chloride was modified on the substrate surface by electrochemical method. Then, it was sintered at 400℃ for 1h under inert gas and coated with cation exchange membrane to prepare a flexible solid-state silver / silver chloride reference electrode. [4] PDMS was used as the substrate for the preparation of silver / silver chloride reference electrode, and the cured PDMS was peeled off from ITO-Ag to obtain PDMS-Ag as the substrate. [5]Silver / silver chloride reference electrodes are fabricated using PDMS as a substrate, and chemical chlorination is used during the fabrication process to obtain the reference electrode. However, these electrodes still suffer from complex fabrication procedures, poor reproducibility, and a short service life. Summary of the Invention

[0005] To overcome the deficiencies in the prior art, the present invention provides a polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride reference electrode. The inventive concept of the present invention is as follows: using carbon foam as the substrate of the reference electrode, electrochemically depositing nanosilver as a working layer, then chlorinating the carbon foam-silver using a chlorination method to prepare a carbon foam-silver / silver chloride electrode, and finally pouring polyvinyl alcohol hydrogel onto the surface of the carbon foam-silver / silver chloride to obtain a polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode.

[0006] The technical solution of the present invention is:

[0007] S1 Foam carbon modification: Use foam carbon as the base material and perform acidification treatment on it;

[0008] Preparation of S2 carbon silver / silver chloride foam:

[0009] A three-electrode system is formed using carbon foam as a working electrode to electrochemically deposit silver. The electrolyte solution used for the electrochemical deposition is a mixed solution of 500-800 mmol / L silver nitrate and 500-800 mmol / L sodium nitrate. The deposition potential is -0.1 V to -0.5 V, and the deposition time is 500 s to 1500 s. The carbon foam on which silver nanoparticles are deposited is called a carbon foam-silver electrode.

[0010] The foam carbon-silver electrode is subjected to electrochemical chlorination, specifically by placing the foam carbon-silver electrode in a 0.1-0.5M hydrochloric acid solution, with a chlorination time of 1000s-2400s and a chlorination potential of 230mV-300mV, to prepare a foam carbon-silver / silver chloride electrode;

[0011] Preparation of S3 polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride reference electrode:

[0012] The polyvinyl alcohol hydrogel mixed solution was evenly poured on the electrode surface, and the foam carbon-silver / silver chloride electrode of the polyvinyl alcohol hydrogel film was obtained by freeze-thaw cycle method;

[0013] The polyvinyl alcohol hydrogel film carbon foam-silver / silver chloride electrode was immersed in a saturated KCl solution for 12 to 24 hours, and then the electrode was transferred to a vacuum oven and dried at 20°C to 50°C for 1.5 hours to 4 hours to obtain a polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride reference electrode.

[0014] More specifically, the acidification process is as follows: washing the carbon foam with water, acetone, and ethanol, and then acidifying the carbon foam with a 10 mM HCl solution to obtain a modified carbon foam that is easy to deposit.

[0015] By electrochemically depositing a nanosilver layer on acidified foam carbon, and then placing the foam carbon-silver electrode in a hydrochloric acid solution and using a simple and easy-to-control electrochemical chlorination method to prepare a rod-shaped nanostructured silver / silver chloride electrode, after optimizing the chlorination conditions, the obtained rod-shaped reference electrode has the characteristics of large specific surface area, more active sites and excellent conductive properties.

[0016] The three-electrode system for preparing the foam carbon-silver electrode is as follows: foam carbon is used as the working electrode, saturated calomel electrode is used as the reference electrode, and platinum wire is used as the counter electrode.

[0017] The three-electrode system for preparing the carbon foam-silver / silver chloride electrode is as follows: the carbon foam-silver electrode is the working electrode, the silver / silver chloride electrode is the reference electrode, and the platinum wire is the counter electrode.

[0018] The freeze-thaw cycle method specifically includes using polyvinyl alcohol (PVA) as raw material, phytic acid (PA) and amino-polysilsesquioxane (NH2-POSS, NP) as cross-linking agents, preparing the above materials into a mixed solution and evenly pouring it on the surface of the dried foam carbon-silver / silver chloride electrode, freezing it at -20°C for 16 hours, thawing it at room temperature for about 3 hours, and repeating the freeze-thaw cycle three times to obtain a foam carbon-silver / silver chloride electrode with a polyvinyl alcohol hydrogel film.

[0019] The present invention utilizes a carbon foam-silver / silver chloride electrode, which is then dried and placed in a culture dish. Polyvinyl alcohol conductive hydrogel is then evenly poured onto the electrode surface to form a hydrogel encapsulation film. The polyvinyl alcohol hydrogel not only increases conductivity but also forms a transparent film on the silver / silver chloride surface, preventing surface material from falling off and improving electrode stability. Furthermore, it prevents the accumulation of charged particles on the electrode surface, preventing significant potential changes at the reference electrode caused by a small electric field.

[0020] Another object of the present invention is to protect the use of the polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride reference electrode in sensors, especially in the detection of adrenaline.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The advantages of using foam carbon as the substrate of the electrode in the present invention are: foam carbon is a lightweight porous foam-like carbon material with a three-dimensional network structure, which has the advantages of low density, high strength, good pore structure, smooth ligaments, no cracks, good conductivity, etc. It can be combined with other metal materials to easily obtain high-performance composite materials, and is often used in chemical industry, aerospace, medicine and other fields.

[0023] The advantages of depositing nanosilver on carbon foam are: nanosilver exhibits nanoscale size effects, a high specific surface area, good electrical conductivity, low resistivity, and high electrical conductivity, making it a widely used material in various fields. Using acidified carbon foam as a substrate facilitates the deposition of the silver layer, and combining carbon foam with nanosilver to form an electrode yields a multifunctional composite material with excellent electrical conductivity.

[0024] The reference electrode of the present invention uses an electrochemical deposition method to deposit nanosilver on a foam carbon substrate in the preparation process. This not only takes advantage of the high purity and uniform particle size of nanosilver, thereby improving the electrode conductivity, but also facilitates subsequent chlorination. The present invention does not use a chemical chlorination method but selects an electrochemical chlorination method to prepare silver chloride. Compared with the chemical chlorination method, the electrochemical chlorination method can control the current and time, making it easier to control the degree of silver chlorination, ensuring stability between each sample. In addition, the electrochemical chlorination method is easy to operate, the chlorination process is simple, and the silver / silver chloride prepared is more stable than silver and is not easily oxidized. At the same time, the present invention also casts a polyvinyl alcohol hydrogel on the electrode surface after chlorination. On the one hand, it can protect the silver / silver chloride on the electrode surface from falling off, improving the electrode stability. On the other hand, it obtains a polyvinyl alcohol hydrogel-foam carbon-silver / silver chloride reference electrode with good ion permeability, good conductivity and stable potential.

[0025] In summary, the present invention uses foam carbon as the substrate of the reference electrode for the first time. Foam carbon has the characteristics of good conductivity and low cost. In addition, using foam carbon as the substrate is conducive to the deposition and chlorination of the silver layer. The foam carbon is electrochemically deposited and chlorinated to prepare a foam carbon-silver / silver chloride reference electrode with a rod-like structure. Silver and conductive polyvinyl alcohol hydrogel are used as auxiliary conductive materials to improve the conductivity of the reference electrode and enhance the signal collection ability. The polyvinyl alcohol hydrogel-foam carbon-silver / silver chloride reference electrode obtained by encapsulating the conductive polyvinyl alcohol hydrogel has better stability and is comparable to commercial reference electrodes. The electrode prepared by the present invention is applied to the electrochemical detection of epinephrine, and its detection signal is significantly higher than that of the commercial reference electrode, showing good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 : Reference electrode preparation and detection flow chart;

[0027] Figure 2: XRD of silver;

[0028] Figure 3 : SEM of carbon foam-silver electrode;

[0029] Figure 4 : XRD of silver / silver chloride;

[0030] Figure 5 : SEM of carbon foam-silver / silver chloride electrode;

[0031] Figure 6 : Comparison of stability test between the reference electrode prepared by the present invention and the commercial reference electrode;

[0032] Figure 7 : Comparison of electrochemical detection between the reference electrode prepared by the present invention and the commercial reference electrode. DETAILED DESCRIPTION

[0033] The present invention is described in detail below by specific examples, but the scope of protection of the present invention is not limited. Unless otherwise specified, the experimental methods adopted in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0034] Example 1

[0035] Step S1: Acidification treatment of foamed carbon

[0036] like Figure 1 As shown, a carbon foam measuring 1.2 x 4 cm was placed in deionized water, ultrasonicated at 15°C for 30 minutes, and dried with nitrogen. It was then ultrasonicated in an acetone solution for 30 minutes and dried with nitrogen. It was then ultrasonicated in ethanol for 30 minutes and dried with nitrogen. Finally, it was soaked in a 10 mM hydrochloric acid solution for 4 hours and allowed to air dry at room temperature. This yielded a modified carbon foam that was easily deposited. Because carbon foam is a porous, low-density, high-strength foam composed of interconnected pores and pore walls, the numerous pores lead to the presence of impurities that can affect the experimental process. Therefore, it was treated with deionized water, acetone, and ethanol. Secondly, it was treated with hydrochloric acid to increase the surface oxygen content of the carbon material, making the carbon foam more susceptible to silver deposition.

[0037] Step S2 Preparation of Carbon Foam-Silver / Silver Chloride

[0038] A three-electrode system was adopted, and the chronoamperometry in the electrochemical workstation was used. The hydrophilically modified foam carbon was used as the working electrode, the saturated calomel electrode was used as the reference electrode, and the platinum wire was used as the counter electrode. The electrolyte solution was a mixed solution of 500mmol / L AgNO3 and 500mmol / L NaNO3 for electrochemical deposition of silver. The deposition potential was -0.2V and the deposition time was 1000s. After electrochemical deposition, nano-granular silver was deposited on the surface of the foam carbon. Figure 2This is the X-ray diffraction pattern of silver. It can be seen from the figure that the nanosilver is deposited on the surface of the foam carbon. Figure 3 This is a scanning electron microscope image of the foam carbon-silver electrode, and its electrode morphology is a rod-like nanostructure.

[0039] The foam carbon-nanosilver electrode was chlorinated with 0.1 mol / L hydrochloric acid solution by electrochemical chlorination method. The electrochemical chlorination time was 1500 s and the chlorination potential was 300 mV to prepare the foam carbon-silver / silver chloride reference electrode. The preparation process of the electrode working layer is as follows: Figure 1 . Figure 4 This is the X-ray diffraction pattern of silver / silver chloride. It can be seen from the figure that there is chlorine element on the nanosilver, indicating that the chlorination of the nanosilver is complete. Figure 5 This is a scanning electron microscope image of the electrochemical chlorination method of the foam carbon-silver / silver chloride electrode. The electron microscope image shows that the electrode morphology is a rod-shaped nanostructure with a rough surface. It can be seen that this electrode has completed chlorination, and the electrode surface has a large specific surface area, which will provide a possibility for providing a more stable potential for the electrochemical detection of adrenaline.

[0040] Step S3 Preparation of polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode

[0041] The hydrogel was cast onto the surface of the prepared carbon foam-silver / silver chloride electrode. The specific process was as follows: 1g of PVA and 0.25g of NH2-POSS were dissolved in 6mL of deionized water and stirred in a 95°C oil bath for 0.5h until homogeneous. 4mL of phytic acid was then added to the solution and stirred for 1.5h until the solution became colorless and transparent. The mixed solution was then ultrasonically shaken for 0.5h until the bubbles disappeared. Finally, the mixed solution was frozen at -20°C for 16h and then thawed at room temperature for approximately 3h. The freeze-thaw cycle was repeated three times to obtain a carbon foam-silver / silver chloride electrode with a polyvinyl alcohol hydrogel film. The carbon foam-silver / silver chloride electrode with the polyvinyl alcohol hydrogel film was then immersed in a saturated KCl solution for 20h. The electrode was then transferred to a vacuum oven and dried at 40°C for 2h to obtain a polyvinyl alcohol conductive hydrogel-carbon foam-silver / silver chloride electrode.

[0042] Example 2

[0043] Step S1: Acidification treatment of foamed carbon

[0044] like Figure 1 As shown, a foam carbon of 1.2*4 cm in size was taken, placed in deionized water and ultrasonicated at 15°C for 30 minutes, blown dry with nitrogen, then placed in an acetone solution and ultrasonicated for 30 minutes and blown dry with nitrogen, then placed in ethanol and ultrasonicated for 30 minutes and blown dry with nitrogen, and finally soaked in a 10 mM hydrochloric acid solution for 4 hours, and left to dry naturally at room temperature for use, to obtain a modified and easily deposited foam carbon.

[0045] Step S2 Preparation of Carbon Foam-Silver / Silver Chloride

[0046] A three-electrode system was adopted, and the chronoamperometry in the electrochemical workstation was used. The hydrophilically modified foam carbon was used as the working electrode, the saturated calomel electrode was used as the reference electrode, and the platinum wire was used as the counter electrode. The electrolyte solution was a mixed solution of 700mmol / L AgNO3 and 700mmol / L NaNO3 for electrochemical deposition of silver. The deposition potential was -0.2V and the deposition time was 500s. After electrochemical deposition, nano-granular silver was deposited on the surface of the foam carbon.

[0047] The foam carbon-nanosilver electrode was chlorinated with 0.1 mol / L hydrochloric acid solution by electrochemical chlorination method. The electrochemical chlorination time was 1500 s and the chlorination potential was 230 mV to prepare a foam carbon-silver / silver chloride reference electrode.

[0048] Step S3 Preparation of polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode

[0049] The hydrogel was cast onto the surface of the prepared carbon foam-silver / silver chloride electrode. The specific process was as follows: 1g of PVA and 0.25g of NH2-POSS were dissolved in 6mL of deionized water and stirred in a 95°C oil bath for 0.5h until homogeneous. 4mL of phytic acid was then added to the solution and stirred for 1.5h until the solution became colorless and transparent. The mixed solution was then ultrasonically shaken for 0.5h until the bubbles disappeared. Finally, the mixed solution was frozen at -20°C for 16h and then thawed at room temperature for approximately 3h. The freeze-thaw cycle was repeated three times to obtain a carbon foam-silver / silver chloride electrode with a polyvinyl alcohol hydrogel film. The carbon foam-silver / silver chloride electrode with a polyvinyl alcohol hydrogel film was then immersed in a saturated KCl solution for 12h. The electrode was then transferred to a vacuum oven and dried at 30°C for 2.5h to obtain a polyvinyl alcohol conductive hydrogel-carbon foam-silver / silver chloride reference electrode.

[0050] Comparative Example 1 Comparison of polyvinyl alcohol conductive hydrogel-foam carbon-silver / silver chloride reference electrode with prior art electrodes

[0051] Table 1 Comparison of electrodes of the present invention and prior art

[0052]

[0053]

[0054] With Tang Zilong and others [1] The prepared electrodes are different. The reference electrode prepared by the present invention uses foam carbon as a substrate, which has good conductivity, and uses hydrogel as a surface film to increase the softness and stability of the electrode.

[0055] Weng Bo et al. [2]Reference electrodes prepared using electroplating are used in the electronic chip field. The present invention uses an electrochemical chlorination method to prepare electrodes for use in sensors for detecting adrenaline. The electrochemical chlorination method involves placing an object in a relatively low-concentration solution, applying an electric current, and allowing the reaction to proceed slowly. During electrochemical chlorination, the current and time can be controlled, allowing for more accurate control of the degree of chlorination. Furthermore, during the experimental process, the results obtained from each experiment or sample are minimally different, resulting in good stability.

[0056] Liu Ruili [3] The electrode prepared by electrochemical deposition using PVB / silver / Nafion as materials is applied to the sensing system, while the electrode prepared by the present invention using foam carbon as a substrate can be applied to the sensor field.

[0057] Sun Jing et al. [4] The silver / silver chloride reference electrode is prepared using PDMS as a substrate, and the cured PDMS is peeled off from the ITO-Ag to obtain the PDMS-Ag substrate. In contrast, the present invention uses carbon foam as a substrate to prepare the silver / silver chloride reference electrode, and also uses a hydroconductive gel to fix the surface to improve the stability of the reference electrode. This is a significant difference in the electrode preparation concept.

[0058] Sun Jing et al. [5] The PDMS / silver / silver chloride reference electrode is prepared by chemical chlorination during the preparation process, and is primarily used in the field of biosensors. The present invention, however, employs an electrochemical chlorination method, which allows for more precise control of the degree and duration of chlorination, eliminating the need for a complex preparation process to produce a preliminary carbon foam-silver / silver chloride reference electrode. To address the poor repeatability of the carbon foam-silver / silver chloride reference electrode during use, the present invention employs a hydrogel cast on the electrode surface, which not only prevents the shedding of silver nanostructures on the electrode surface but also increases the electrode's service life, making it suitable for adrenaline detection.

[0059] Comparative Example 2 Preparation of Carbon Material Modified Partial Pressure Type Silver-Silver Chloride Electrode

[0060] The production process is as follows: soak the carbon fiber in a solution composed of tetraethyl orthosilicate, silane coupling agent, and ethanol, seal it with plastic wrap for 12 hours after soaking, heat it in a heating furnace, take it out after drying and cool it to room temperature, then use enameled wire as the conductor, remove the paint on one end and fully soak it with conductive silver glue, insert it into a bundle of modified carbon fiber coated with concentrated nitric acid and silica sol, so that the carbon fiber and the conductor are in full contact, use conductive silver glue to bond at the connection, and seal it with epoxy resin as the experimental group. At the same time, a bundle of unmodified carbon fibers is encapsulated using the same method as the blank control group for morphological observation and electrochemical testing. The surface of the electrode prepared in this comparative example has a large number of charged particles enriched, causing the reference electrode to cause a significant change in potential due to a small electric field.[6-7] .

[0061] Example 3 Comparison of Stability Tests of Polyvinyl Alcohol Conductive Hydrogel-Carbon Foam-Silver / Silver Chloride Reference Electrode and Commercial Reference Electrode

[0062] The polyvinyl alcohol hydrogel-foam carbon-silver / silver chloride electrode prepared by the present invention and the commercial silver / silver chloride reference electrode were used as working electrodes, platinum wire as counter electrode, and silver / silver chloride as reference electrode, respectively, and placed in 3M KCl aqueous solution for OCP stability test. The test results are shown in FIG. Figure 6 As shown, the results show that the conductivity of the electrode prepared by the present invention remains stable within 500s, which is comparable to that of the commercial reference electrode.

[0063] Example 4 Electrochemical detection using polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride reference electrode

[0064] The polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode prepared by the present invention and commercial silver / silver chloride were used as reference electrodes, a gold electrode as a working electrode, and a platinum wire as a counter electrode to form a three-electrode system fixed in an electrochemical workstation. The electrochemical detection of epinephrine was carried out using a differential pulse method, wherein the potential was -0.2 to 1 V, the concentration of epinephrine was 1 mmol / L, and the buffer solution was a 0.1 mol / L phosphate buffer solution. The experimental results are shown as follows: Figure 7 The results show that the reference electrode prepared by the present invention has a higher signal response when detecting epinephrine, indicating that the reference electrode of the present invention can provide a more stable potential, so that the signal of the working electrode when detecting epinephrine is higher than that of the commercial reference electrode, which also shows that the reference electrode of the present invention is convenient for electrochemical detection of epinephrine.

[0065] The above description is only a preferred specific implementation method of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, can make equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, which should be covered by the protection scope of the present invention.

[0066] References

[0067] [1] Tang Zilong, Zhang Xinghua, Nie Xinhui. Method for preparing reference electrode using Ag / AgCl solid powder[P]. CN102368059A, 2012-03-07.

[0068] [2] Weng Bo, Diao Jianglin, Li Changming. Inkjet printed silver / silver chloride reference electrode based on nanosilver ink and its preparation method [P]. CN104614428A, 2015-05-13.

[0069] [3] Liu Ruili, Shen Chaochao, Xi Xin, Wu Dongqing, Tang Wei, Guo Xiaojun, Su Yuezeng. A fibrous flexible solid-state silver / silver chloride reference electrode and its preparation method and application [P]. CN113433183A, 2021-09-24.

[0070] [4] Sun Jing, Wang Qingxiang, Shen Guijun, Lang Mingfei. A method for preparing reusable PDMS-based Ag / AgCl microelectrodes and their application [P]. CN108195911B, 2020-05-19.

[0071] [5] Sun Jing, Wang Qingxiang, Shen Guijun, Lang Mingfei. A method for preparing and applying a reusable PDMS-based Ag / AgCl microelectrode[P]. CN108195911A, 2018-06-22.

[0072] [6] Wang Zechen, Lin Jun, Xin Qing, Zang Yue. Preparation and performance research of new carbon fiber marine electric field electrode[J]. Chinese Journal of Scientific Instrument, 2019, 40(09): 52-60. DOI: 10.19650 / j.cnki.cjsi.J1904929.

[0073] [7] Xiao Haijian, Li Hongxia, Song Yusu. Research progress of Ag / AgCl ocean electric field detection electrode [J / OL]. Equipment Environmental Engineering: 1-9 [2022-11-04].

Claims

1. A method for preparing a polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride reference electrode, characterized in that: S1 Foam carbon modification: Use foam carbon as the base material and perform acidification treatment on it; Preparation of S2 carbon silver / silver chloride foam: Silver is electrochemically deposited in a three-electrode system using carbon foam as a working electrode, wherein the electrolyte solution used for the electrochemical deposition is a mixed solution of 500-800 mmol / L silver nitrate and 500-800 mmol / L sodium nitrate, the deposition potential is -0.1 V to -0.5 V, and the deposition time is 500 s to 1500 s, thereby obtaining a carbon foam-silver electrode; The foam carbon-silver electrode is subjected to electrochemical chlorination, specifically by placing the foam carbon-silver electrode in a 0.1-0.5M hydrochloric acid solution, with a chlorination time of 1000s-2400s and a chlorination potential of 230mV-300mV, to prepare a foam carbon-silver / silver chloride electrode; Preparation of S3 polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride reference electrode: The polyvinyl alcohol hydrogel mixed solution was evenly poured on the electrode surface, and the foam carbon-silver / silver chloride electrode of the polyvinyl alcohol hydrogel film was obtained by freeze-thaw cycle method; The polyvinyl alcohol hydrogel film carbon foam-silver / silver chloride electrode was immersed in a saturated KCl solution for 12 to 24 hours, and then the electrode was transferred to a vacuum oven and dried at 20°C to 50°C for 1.5 hours to 4 hours to obtain a polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride reference electrode.

2. The preparation method according to claim 1, wherein The acidification treatment process is as follows: washing the foam carbon with water, acetone and ethanol, and then acidifying the foam carbon with a 10 mM HCl solution to obtain the modified foam carbon.

3. The preparation method according to claim 1, wherein The three-electrode system for preparing the foam carbon-silver electrode is as follows: foam carbon is used as the working electrode, saturated calomel electrode is used as the reference electrode, and platinum wire is used as the counter electrode.

4. The preparation method according to claim 1, wherein The three-electrode system for preparing the carbon foam-silver / silver chloride electrode is as follows: the carbon foam-silver electrode is the working electrode, the silver / silver chloride electrode is the reference electrode, and the platinum wire is the counter electrode.

5. Use of the polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride reference electrode prepared by the preparation method as claimed in claim 1 in a sensor.

6. The use according to claim 5, characterized in that: Application of polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride reference electrode in adrenaline detection.

Images