In-situ curing high-sensitivity formaldehyde electrochemical sensor and preparation method thereof

Abstract

The invention provides an in-situ cured high-sensitivity formaldehyde electrochemical sensor and a preparation method thereof. The electrochemical sensor comprises a flexible substrate; the three-electrode system is arranged on the flexible substrate and comprises a working electrode, a counter electrode and a reference electrode; the catalyst layer is only arranged on the working electrode; the catalyst layer is prepared from slurry formed by mixing a catalyst, a Nafion solution and a solvent; the solid electrolyte layer covers the three-electrode system and the catalytic layer, the solid electrolyte layer is formed by in-situ curing of a Nafion solution, and the sensor has the advantages of high sensitivity, wide linear response range, low detection limit, high selectivity, low cost and the like, and can be widely applied to the fields of indoor environment monitoring, human body exhaled air disease screening and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of gas sensing, and relates to an in-situ solidified high-sensitivity formaldehyde electrochemical sensor and a preparation method thereof, in particular to an in-situ solidified high-sensitivity formaldehyde electrochemical sensor based on a Nafion solution and a preparation method thereof. BACKGROUND

[0003] The electrochemical gas sensor becomes an ideal tool for formaldehyde detection due to high sensitivity, high selectivity, low cost and real-time monitoring at room temperature. However, the existing technology has the following defects: first, in terms of the sensing layer: the enzyme-based sensor is limited by the enzyme reaction activity, is easily affected by the environment temperature and humidity, and has a short service life; the chemical reaction probe-based sensor needs to invest a lot of effort in synthesizing and screening reaction reagents, and has poor stability. Second, in terms of the electrolyte: the liquid electrolyte is easy to leak, resulting in failure of the sensor; the inorganic solid-state electrolyte needs to work at high temperature (250-500℃), and has large power consumption. Third, in terms of the device structure: the liquid electrolyte sensor needs to be tightly packaged, and has a complex structure; the inorganic solid-state electrolyte sensor needs to be integrated with a heating device, and has a complex structure.

[0004] Therefore, based on the above problems, it is urgent to develop a high-sensitivity formaldehyde electrochemical sensor which works at room temperature, has a simple structure, good stability and low cost. SUMMARY

[0005] Based on the above reasons, the present application aims to solve the technical problems of the existing formaldehyde electrochemical sensor, such as liquid electrolyte leakage, inorganic solid-state electrolyte needing high-temperature work, poor stability of biological enzyme sensor, and complex device structure, and provides an in-situ solidified high-sensitivity formaldehyde electrochemical sensor based on a Nafion solution and a preparation method thereof, to realize high-sensitivity, wide linear response range, and low detection limit of HCHO selective quantitative detection at room temperature.

[0006] To achieve the above purpose, the application adopts the following technical solutions:

[0007] An in-situ solidified high-sensitivity formaldehyde electrochemical sensor based on a Nafion solution, comprising:

[0008] a flexible substrate;

[0009] a three-electrode system arranged on the flexible substrate, the three-electrode system comprising a working electrode (WE), a counter electrode (CE) and a reference electrode (RE);

[0010] a catalyst layer arranged only on the working electrode, the catalyst layer being made of a slurry mixed by a catalyst, a Nafion solution and a solvent;

[0011] • A solid state electrolyte layer covering the three electrode system and the catalytic layer, which is formed by in-situ solidification of Nafion solution.

[0012] Preferably, the flexible substrate can be a flexible non-air permeable substrate or a flexible air permeable substrate, which is made of one of polyimide, polyethylene terephthalate, polytetrafluoroethylene or polyvinylidene fluoride, preferably polyimide, and has a thickness of 0.1 mm ~ 3 mm, preferably 0.2 mm ~ 2 mm.

[0013] Preferably, the flexible non-air permeable substrate can be used directly or can be processed to have a microporous structure with a pore size of 1 ~ 10 μm, preferably 4 ~ 8 μm, and a porosity of 1 ~ 10%, preferably 3 ~ 8%.

[0014] In addition, the solid state electrolyte layer formed on the substrate can be used as both a proton conducting medium and a gas diffusion layer.

[0015] Preferably, the catalyst in the catalytic layer is Pt / C catalyst or any one of Pt, Pd, Au, Ag, Ni or two or more of them in any proportion. In the Pt / C catalyst, the mass percentage of Pt is 10% ~ 60%, further preferably 30% ~ 60%. The thickness of the catalytic layer is 5 ~ 50 μm, preferably 15 μm ~ 35 μm.

[0016] Preferably, in the mixed slurry of the catalytic layer, the mass ratio of the catalyst, Nafion solution and solvent, based on the mass of the catalyst, is 0.5 ~ 10: 1 ~ 20: 5 ~ 100, preferably 1 ~ 5: 2 ~ 10: 10 ~ 50.

[0017] Preferably, the solid state electrolyte layer is formed by drop coating and solidification of Nafion solution with a mass fraction of 5 wt% ~ 20 wt%, further preferably 7 ~ 15 wt% Nafion solution. The thickness of the solid state electrolyte layer is 20 μm or less, preferably 2 μm ~ 8 μm.

[0018] Another technical solution of the present application is:

[0019] A method for preparing an in-situ solidified formaldehyde electrochemical sensor as described above, comprising the following steps:

[0020] • Step one: preparation of a flexible three electrode system

[0021] On the flexible substrate, a three electrode system is obtained by screen printing, 3D jet printing or doctor blade coating process using electrode slurry, and a catalytic layer coating area is reserved in the working electrode area;

[0022] Step 2: Catalyst layer preparation

[0023] The catalyst, Nafion solution, and solvent were mixed in proportion and ultrasonically dispersed to obtain a catalytic slurry.

[0024] The catalytic slurry is drop-coated onto the catalyst coating area reserved on the working electrode in step one, and a catalytic layer is formed after curing.

[0025] Step 3: In-situ solidification of Nafion solid electrolyte

[0026] Nafion solution was drop-coated onto the surface of the device, which covered the three-electrode system and the catalyst layer, so that it uniformly covered the working electrode, counter electrode and reference electrode;

[0027] The device is cured at room temperature after being drop-coated to form a continuous solid electrolyte layer.

[0028] Preferably, in step one, the flexible substrate can be a flexible non-permeable substrate or a flexible permeable substrate. When it is a flexible non-permeable substrate, it can be used directly or a microporous structure can be processed. The microporous structure is formed on the thin plate by laser micro-hole processing, and the formed pore diameter is 1~10 μm, preferably 4~8 μm, and the porosity is 1~10%, preferably 3~8%. The material is one of polyimide, polyethylene terephthalate, polytetrafluoroethylene, or polyvinylidene fluoride, preferably polyimide. The thickness of the substrate thin plate is 0.1 mm~3 mm, preferably 0.2~2 mm.

[0029] The three-electrode system is manufactured by screen printing, 3D inkjet printing or scraping process, and the electrode paste is silver paste and / or carbon paste.

[0030] Preferably, in step two, the catalyst is a Pt / C catalyst or is composed of any one or more metals selected from Pt, Pd, Au, Ag, and Ni in any proportion. In the Pt / C catalyst, the mass percentage of Pt is 10% to 60%, more preferably 30% to 60%.

[0031] The Nafion solution is a 5 wt% Nafion solution, and the solvent is anhydrous ethanol, acetonitrile, N,N-dimethylformamide, or N,N-dimethylacetamide. In the catalyst slurry, the mass ratio of catalyst, Nafion solution, and solvent is 0.5~10:1~20:5~100.

[0032] Preferably, in step two, the amount of the catalyst slurry being dropped is 1-20 μL, preferably 5-10 μL, the curing conditions are 40℃-80℃ for 5-30 minutes, preferably 60℃ for 10 minutes, and the thickness of the catalyst layer after curing is 5-50 μm, preferably 15-35 μm.

[0033] Preferably, in step three, the Nafion solution is a Nafion solution with a mass fraction of 5 wt% to 20 wt%, and the curing conditions are curing at room temperature for 12 to 24 hours. The thickness of the formed solid electrolyte layer is less than 20 μm, preferably less than 8 μm and more than 2 μm.

[0034] Beneficial effects

[0035] The in-situ cured high-sensitivity formaldehyde electrochemical sensor provided by this invention has the following advantages compared with traditional formaldehyde electrochemical sensors: High sensitivity: A high sensitivity of 0.2 μA / ppm is achieved through optimized slurry ratio and catalyst layer modification strategy; Wide linear response range: Linear response can be achieved in the HCHO concentration range of 500 ppb ~ 100 ppm; Low detection limit: The detection limit can reach 2.5 ppb; High selectivity: It has good anti-interference ability against interfering gases such as ethanol, acetaldehyde, toluene, and acetone; In addition, the Nafion solid electrolyte enables the sensor to operate at room temperature without the need for a heating device; Furthermore, the planar three-electrode design eliminates the need for a complex packaging shell, resulting in a simple device structure; Moreover, this preparation method uses at most 60% platinum metal, so the amount of precious metal platinum is reduced by at least 40%, thus achieving low cost and reducing preparation cost.

[0036] In summary, the present invention provides a method for preparing a highly sensitive formaldehyde electrochemical sensor with in-situ curing. This method is simple to operate, low in cost, and readily available, and can produce an electrochemical sensor device with a simple structure and better-than-expected performance. Attached Figure Description

[0037] Appendix Figure 1 This is a schematic diagram of the preparation method of the electrochemical sensor of the present invention;

[0038] Appendix Figure 2 The chronoamperometry curves of the electrochemical sensor of the present invention at 5 ppm - 90 ppm HCHO are shown.

[0039] Appendix Figure 3 The electrochemical sensor of the present invention has a chronoamperometry test curve (left) and a linear fitting line between concentration and current (right) in 500 ppb-5 ppm HCHO.

[0040] AppendixFigure 4 For the selective testing of electrochemical sensors;

[0041] Appendix Figure 5 For long-term stability testing of electrochemical sensors. Detailed Implementation

[0042] The following detailed description of the in-situ cured high-sensitivity formaldehyde electrochemical sensor and its preparation method of the present invention is provided through specific embodiments. However, the following embodiments are merely examples of the present invention, and the specific content disclosed therein is not intended to limit the scope of protection of the present invention.

[0043] This invention provides a method for preparing a highly sensitive formaldehyde electrochemical sensor with in-situ curing (see details for specific steps). Figure 1 ):

[0044] Fabrication of the flexible three-electrode system: Thin sheets of polyimide, polyethylene terephthalate, polytetrafluoroethylene, polyvinylidene fluoride, and polyimide of a certain thickness are used directly or formed into a microporous structure through laser micropore processing, thereby controlling the gas diffusion path. The three-electrode system (WE / CE / RE) is fabricated using methods such as 3D inkjet printing, blade coating, and screen printing, using silver / carbon paste printing, with a pre-reserved catalyst layer coating area in the WE region.

[0045] Catalyst layer preparation: The catalyst, Nafion solution, and anhydrous ethanol were mixed in a certain proportion, ultrasonically dispersed, and then drop-coated onto the working electrode. After curing and drying, a catalyst layer with a thickness of less than 20 μm was formed.

[0046] In-situ solid electrolyte curing with Nafion: Nafion solution is drop-coated onto the surface of the three electrodes and cured at room temperature for 24 hours to form a continuous solid electrolyte layer with a thickness of less than 10 μm, which covers the working electrode, counter electrode and reference electrode.

[0047] This invention provides several embodiments, detailing the preparation process, testing methods, and result data of the formaldehyde electrochemical sensor, demonstrating that the invention has advantages such as high sensitivity, wide linear response range, low detection limit, high selectivity, and low cost.

[0048] Example 1: Preparation of a highly sensitive formaldehyde electrochemical sensor with in-situ curing

[0049] Step 1: Fabrication of the flexible three-electrode system

[0050] A 0.3 mm thick polyimide film was used as the flexible, non-permeable substrate material. A microporous structure with a pore size of 5 μm and a porosity of 5% was then fabricated on the substrate using laser micropore processing technology to control the gas diffusion path. Subsequently, silver / carbon paste was printed on the substrate using screen printing to form a three-electrode system (WE / CE / RE), with a catalytic layer coating area reserved in the working electrode region. At this stage, the working electrode diameter was 4 mm, and the spacing between the three electrodes was 10 mm.

[0051] Step 2: Catalyst layer preparation

[0052] 60% Pt / C catalyst, 5 wt% Nafion solution and anhydrous ethanol were mixed at a mass ratio of 1:2:10 and ultrasonically dispersed for 10 minutes to obtain a uniform catalyst slurry. Then, 5 μL of the catalyst slurry was taken with a micropipette and dropped onto the reserved catalyst coating area of ​​the working electrode. The device after drop coating was placed on a 60℃ heating stage and cured for 10 minutes to form a catalyst layer with a thickness of about 20 μm.

[0053] Step 3: In-situ solidification of Nafion solid electrolyte

[0054] A 5 wt% Nafion solution was drop-coated onto the surface of the device, which covered the three-electrode system and the catalyst layer, ensuring uniform coverage of the working electrode, counter electrode, and reference electrode. The drop-coated device was then left to cure at room temperature for 24 hours, forming a continuous solid electrolyte layer with a thickness of approximately 8 μm. This resulted in the formation of an in-situ cured formaldehyde electrochemical sensor 1.

[0055] Performance testing

[0056] Timing current sensitivity test:

[0057] The in-situ cured high-sensitivity formaldehyde electrochemical sensor prepared in Example 1 was placed in a gas chamber, and different concentrations of HCHO gas (5 ppm - 90 ppm) were introduced, and the current response values ​​were recorded. The results are as follows: Figure 2 As shown in the figure, within the formaldehyde concentration range of 10-90 ppm, the current response value increases with increasing formaldehyde concentration, indicating that the device has a good response to formaldehyde. Furthermore, when the formaldehyde concentration returns to a low range of 5-25 ppm, the sensor maintains approximately the same current response value, and the current response value increases with increasing formaldehyde concentration, indicating good stability of the sensor. Additionally, it can be seen that the current response value is 9.694 μA at a formaldehyde concentration of 50 ppm, demonstrating that the sensor of this invention is sensitive to HCHO, with a sensitivity of approximately 0.2 μA / ppm.

[0058] Example 2:

[0059] Preparation process:

[0060] Step 1: Fabrication of the flexible three-electrode system

[0061] A 0.5 mm thick polyimide sheet was used as the flexible substrate material. Silver / carbon paste was then printed onto the substrate using inkjet printing to form a three-electrode system (WE / CE / RE), with a catalytic layer coating area reserved in the working electrode region. The working electrode diameter was 4 mm, and the spacing between the three electrodes was 10 mm.

[0062] Step 2: Catalyst layer preparation

[0063] 60% Pt / C catalyst, 5 wt% Nafion solution and anhydrous ethanol were mixed at a mass ratio of 0.5:3:8 and ultrasonically dispersed for 10 minutes to obtain a uniform catalyst slurry. Then, 5 μL of the catalyst slurry was taken with a micropipette and dropped onto the reserved catalyst coating area of ​​the working electrode. The device after drop coating was placed on a 60℃ heating stage and cured for 10 minutes to form a catalyst layer with a thickness of about 25 μm.

[0064] Step 3: In-situ solidification of Nafion solid electrolyte

[0065] A 10 wt% Nafion solution was drop-coated onto the surface of the device, which covered the three-electrode system and the catalyst layer, ensuring uniform coverage of the working electrode, counter electrode, and reference electrode. The drop-coated device was then placed at room temperature and cured for 12 hours to form a continuous solid electrolyte layer with a thickness of approximately 10 μm. This resulted in the formation of an in-situ cured formaldehyde electrochemical sensor 2.

[0066] Performance testing

[0067] Linear range and detection limit test

[0068] Chronoamperometry: The formaldehyde electrochemical sensor prepared in Example 2 was placed in a gas chamber, and different concentrations of HCHO gas (500 ppb - 5 ppm) were introduced. The current response values ​​were recorded. The results are as follows: Figure 3 As shown in the left figure, within the formaldehyde concentration range of 500 ppb-5 ppm, the current response value increases with increasing formaldehyde concentration, indicating that the sensor can detect low concentrations of formaldehyde. Furthermore, it can be seen that there is a linear relationship between the HCHO concentration of 500 ppb-5 ppm and the sensor's current response value (R0). 2=0.996 (right figure). The sensor detection limit is calculated using LOD=(k*σ) / S, with a limit of 2.5 ppb. In this formula, LOD represents the detection limit, k is the signal-to-noise ratio coefficient (usually 3), σ is the standard deviation of the background signal, and S is the slope of the fitted curve. The right figure shows a linear relationship between formaldehyde concentration (500 ppb - 5 ppm) and the current response value; the current response value increases linearly with formaldehyde concentration.

[0069] Example 3:

[0070] Preparation process:

[0071] Step 1: Fabrication of the flexible three-electrode system

[0072] A 0.3 mm thick polyimide sheet was used as the flexible, non-permeable substrate material. Laser micropore processing technology was then used to fabricate a microporous structure with a pore size of 10 μm and a porosity of 5% on the substrate to control the gas diffusion path. Subsequently, silver / carbon paste was screen-printed onto the substrate to form a three-electrode system (WE / CE / RE), with a catalytic layer coating area reserved in the working electrode region. At this stage, the working electrode diameter was 4 mm, and the spacing between the three electrodes was 10 mm.

[0073] Step 2: Catalyst layer preparation

[0074] 40% Pt / C catalyst, 10 wt% Nafion solution and anhydrous ethanol were mixed at a mass ratio of 2:5:10 and ultrasonically dispersed for 10 minutes to obtain a uniform catalyst slurry. Then, 10 μL of the catalyst slurry was taken with a micropipette and dropped onto the reserved catalyst coating area of ​​the working electrode. The device after drop coating was placed on a 60℃ heating stage and cured for 10 minutes to form a catalyst layer with a thickness of about 20 μm.

[0075] Step 3: In-situ solidification of Nafion solid electrolyte

[0076] A 10 wt% Nafion solution was drop-coated onto the surface of the device, which covered the three-electrode system and the catalyst layer, ensuring uniform coverage of the working electrode, counter electrode, and reference electrode. The drop-coated device was then placed at room temperature and cured for 12 hours to form a continuous solid electrolyte layer with a thickness of approximately 15 μm. This resulted in the formation of an in-situ cured formaldehyde electrochemical sensor.

[0077] Selective performance testing

[0078] Chronocurrent testing: The formaldehyde electrochemical sensor 3 prepared in Example 3 was placed in a gas chamber, and interfering gases such as nitric oxide, ethanol, acetaldehyde, toluene, acetone, isoprene, and ammonia were introduced respectively. The ratio of the current response value to the blank background signal was recorded. The results are as follows: Figure 4As shown, the ratio of the current response value to the blank background signal for 50 ppm formaldehyde is 7.54, for 100 ppm nitric oxide it is 1.34, and for 100 ppm ethanol it is 1.03. The ratios of the current response value to the blank background signal for other gases are all less than 1. The specific ratios of the current response value to the blank background signal for each gas are shown in Table 1 below.

[0079] Table 1

[0080] Gas [CAT] / [I0] 45 ppm C5H8 0.50 50 ppm NH3 0.16 50 ppm CH3COCH3 0.61 50 ppm C7H8 0.73 100 ppm C2H5OH 1.03 100 ppm CH3CHO 0.48 100 ppm NO 1.34 50 ppm HCHO 7.54

[0081] From the data in the table above and Figure 4 This indicates that the electrochemical sensor of the present invention has excellent high sensitivity and selectivity for HCHO.

[0082] Example 4:

[0083] Preparation process:

[0084] Step 1: Fabrication of the flexible three-electrode system

[0085] A 1 mm thick polyimide sheet was used as the flexible, non-permeable substrate material. Microporous structures with a pore size of 5 μm and a porosity of 8% were fabricated on the substrate using laser micropore processing technology to control the gas diffusion path. Subsequently, silver / carbon paste was printed on the substrate using inkjet printing to form a three-electrode system (WE / CE / RE), with a pre-reserved catalytic layer coating area in the working electrode region. At this stage, the working electrode diameter was 4 mm, and the spacing between the three electrodes was 10 mm.

[0086] Step 2: Catalyst layer preparation

[0087] 40% Pt / C catalyst, 5 wt% Nafion solution and anhydrous ethanol were mixed at a mass ratio of 1:4:100 and ultrasonically dispersed for 10 minutes to obtain a uniform catalyst slurry. Then, 5 μL of the catalyst slurry was taken with a micropipette and dropped onto the reserved catalyst coating area of ​​the working electrode. The device after drop coating was placed on a 60℃ heating stage and cured for 10 minutes to form a catalyst layer with a thickness of about 20 μm.

[0088] Step 3: In-situ solidification of Nafion solid electrolyte

[0089] A 5 wt% Nafion solution was drop-coated onto the surface of the device, which covered the three-electrode system and the catalyst layer, ensuring uniform coverage of the working electrode, counter electrode, and reference electrode. The drop-coated device was then left to cure at room temperature for 24 hours, forming a continuous solid electrolyte layer with a thickness of approximately 8 μm. This resulted in the formation of an in-situ cured formaldehyde electrochemical sensor.

[0090] Long-term stability test

[0091] Chronocurrent testing: The formaldehyde electrochemical sensor 4 prepared in Example 4 was placed in a gas chamber, and 100 ppm HCHO gas was introduced. The current response value was recorded, and the test was continued for 16 days to observe the stability of the sensor's response. The results are as follows: Figure 5 As shown in the figure, the electrochemical sensor of the present invention maintains a stable response to 100 ppm HCHO for 16 days, and the specific values ​​are shown in Table 2 below, which indicates that the sensor has good long-term stability.

[0092] Table 2

[0093] Time (days) Current response value (microampere) 5 24.43 9 20.22 13 22.14 16 22.45

[0094] Therefore, the in-situ cured high-sensitivity formaldehyde electrochemical sensor prepared by the preparation method of the present invention achieves a high sensitivity of 0.2 μA / ppm; and can achieve a wide range of linear response in the HCHO concentration range of 500 ppb ~ 100 ppm; in addition, it has high selectivity among a variety of interfering gases and a very low detection limit of 2.5 ppb.

[0095] Therefore, the in-situ cured high-sensitivity formaldehyde electrochemical sensor of the present invention is a high-sensitivity formaldehyde electrochemical sensor that can operate at room temperature, has a simple structure, good stability, and low cost. It can be widely used in indoor environmental monitoring and human exhaled breath disease screening and other fields.

Claims

1. A highly sensitive formaldehyde electrochemical sensor with in-situ curing, characterized in that, include: Flexible substrate; • A three-electrode system disposed on the flexible substrate, the three-electrode system comprising a working electrode, a counter electrode, and a reference electrode; • A catalyst layer disposed only on the working electrode, the catalyst layer being made of a slurry of a mixture of catalyst, Nafion solution and solvent; • A solid electrolyte layer covering the three-electrode system and the catalyst layer, wherein the solid electrolyte layer is formed by in-situ solidification of Nafion solution.

2. The electrochemical sensor according to claim 1, characterized in that, The flexible substrate can be a flexible non-permeable substrate or a flexible permeable substrate, and the material of the flexible substrate is selected from one of polyimide, polyethylene terephthalate, polytetrafluoroethylene or polyvinylidene fluoride. The thickness of the substrate is 0.1 mm to 3 mm.

3. The electrochemical sensor according to claim 1, characterized in that, The three-electrode system is manufactured by screen printing, 3D inkjet printing or scraping process, and the electrode paste is silver paste and / or carbon paste.

4. The electrochemical sensor according to claim 1, characterized in that, The catalyst is a Pt / C catalyst or a combination of any one or more metals selected from Pt, Pd, Au, Ag, and Ni in any proportion, wherein the mass percentage of Pt in the Pt / C catalyst is 10% to 60%.

5. The electrochemical sensor according to claim 1, characterized in that, The thickness of the catalyst layer is 5-50 μm.

6. The electrochemical sensor according to claim 1, characterized in that, The thickness of the solid electrolyte layer is less than 20 μm.

7. A method for preparing a highly sensitive formaldehyde electrochemical sensor with in-situ curing according to any one of claims 1 to 6, characterized in that, Includes the following steps: Step 1: Fabrication of the flexible three-electrode system On a flexible substrate, a three-electrode system is obtained by screen printing, 3D jet printing or blade coating using electrode paste, and a catalyst layer coating area is reserved in the working electrode area. Step 2: Catalyst layer preparation The catalyst, Nafion solution, and solvent were mixed in proportion and ultrasonically dispersed to obtain a catalytic slurry. The catalytic slurry is drop-coated onto the catalyst coating area reserved on the working electrode in step one, and a catalytic layer is formed after curing. Step 3: In-situ solidification of Nafion solid electrolyte Nafion solution was drop-coated onto the surface of the device, which covered the three-electrode system and the catalyst layer, so that it uniformly covered the working electrode, the counter electrode and the reference electrode. The device is cured at room temperature after being drop-coated to form a continuous solid electrolyte layer.

8. The preparation method according to claim 7, characterized in that, In step one, the flexible substrate can be a flexible non-permeable substrate or a flexible permeable substrate, and the substrate material is one of polyimide, polyethylene terephthalate, polytetrafluoroethylene or polyvinylidene fluoride; the thickness of the substrate is 0.1 mm to 3 mm.

9. The preparation method according to claim 7, characterized in that, In step two, the mass ratio of catalyst, Nafion solution, and solvent in the catalytic slurry is 0.5~10:1~20:5~100. The catalyst is a Pt / C catalyst or a mixture of any one or more metals selected from Pt, Pd, Au, Ag, and Ni in any proportion. In the Pt / C catalyst, the mass percentage of Pt is 10%~60%. The Nafion solution is a 5 wt% Nafion solution, and the solvent is anhydrous ethanol, acetonitrile, N,N-dimethylformamide, or N,N-dimethylacetamide.

10. The preparation method according to claim 7, characterized in that, In step three, the Nafion solution is a Nafion solution with a mass fraction of 5 wt% to 20 wt%, and the curing conditions are curing at room temperature for 12 to 24 hours, forming a solid electrolyte layer with a thickness of less than 20 μm.

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