Electrochemical hydrogen cyanide gas sensor working electrode, preparation method thereof and electrochemical hydrogen cyanide gas sensor

Abstract

The invention relates to an electrochemical hydrogen cyanide gas sensor working electrode, a preparation method thereof and an electrochemical hydrogen cyanide gas sensor, and belongs to the technical field of gas sensors. The preparation method of the working electrode of the electrochemical hydrogen cyanide gas sensor comprises the following steps: mixing a binder solution, a polytetrafluoroethylene emulsion, a nano material and a conductive agent to obtain slurry, brushing the slurry on a waterproof gas-permeable membrane, baking and pressing to obtain the working electrode of the electrochemical hydrogen cyanide gas sensor. The slurry of the working electrode of the electrochemical hydrogen cyanide gas sensor is easy to prepare and convenient to brush, and automatic large-batch brushing can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of gas sensors, and in particular relates to an electrochemical hydrogen cyanide gas sensor working electrode and a preparation method thereof, and an electrochemical hydrogen cyanide gas sensor. Background Art

[0002] Hydrogen cyanide is a highly toxic gas widely used in industries such as organic chemicals, electroplating, mining and metallurgy, paints, dyes, and rubber. Improper use or leakage of hydrogen cyanide gas can pose a serious threat to the safety of nearby personnel. Low concentrations (10-50 ppm) can cause headaches, nausea, vomiting, and breathing difficulties. Inhalation of even small amounts of high concentrations (>100 ppm) can lead to loss of consciousness, convulsions, respiratory arrest, and death within minutes. Skin contact with liquid hydrogen cyanide or high-concentration gas can cause burns or systemic poisoning. Currently, to prevent hydrogen cyanide leaks, gas detection tubes, thermal conductivity detectors, and gas chromatographs are commonly used to monitor hydrogen cyanide gas concentrations. However, these devices are inaccurate, time-consuming, and inconvenient to carry. Against this backdrop, there is a growing demand for hydrogen cyanide gas sensors for safety monitoring. Summary of the Invention

[0003] A first object of the present invention is to provide an electrochemical hydrogen cyanide gas sensor working electrode, which can quickly and accurately detect hydrogen cyanide gas.

[0004] The second object of the present invention is to provide a method for preparing a working electrode of an electrochemical hydrogen cyanide gas sensor.

[0005] A third object of the present invention is to provide an electrochemical hydrogen cyanide gas sensor.

[0006] In order to achieve the above objectives, the technical solution adopted by the present invention is:

[0007] A method for preparing a working electrode of an electrochemical hydrogen cyanide gas sensor comprises the following steps: mixing a binder solution, a polytetrafluoroethylene emulsion, a nanomaterial and a conductive agent to obtain a slurry, brushing the slurry on a waterproof breathable membrane, and baking and pressing the slurry to obtain the electrode.

[0008] Furthermore, the volume ratio of the binder solution to the polytetrafluoroethylene emulsion is 1:1-1.5, the mass fraction of the binder solution is 2-4%, and the solid content of the polytetrafluoroethylene emulsion is 30-60%.

[0009] Furthermore, 0.1 to 0.2 g of nanomaterial is added to each mL of the binder solution, and 0.015 to 0.020 g of conductive agent is added to each mL of the binder solution.

[0010] Furthermore, the conductive agent is graphite; the nanomaterial is silver nanomaterial; the binder is one or more of perfluorosulfonic acid polymer solution, cellulose, and polyacrylic acid, and the solid content of the perfluorosulfonic acid polymer solution is 20-30%.

[0011] Furthermore, the baking temperature is 150-250°C.

[0012] Furthermore, the slurry is brushed onto the waterproof breathable membrane by screen printing, and the waterproof breathable membrane is a polytetrafluoroethylene membrane.

[0013] A working electrode for an electrochemical hydrogen cyanide gas sensor is prepared by using the above-mentioned method for preparing a working electrode for an electrochemical hydrogen cyanide gas sensor.

[0014] An electrochemical hydrogen cyanide gas sensor comprises the above-mentioned electrochemical hydrogen cyanide gas sensor working electrode.

[0015] Furthermore, it also includes a shell, the interior of the shell is hollow, and the upper end of the shell is open; an upper cover is provided in the shell to seal the shell, and an air inlet is provided on the upper cover; a metal pin is connected to the lower end of the shell; the working electrode of the electrochemical hydrogen cyanide gas sensor is located below the upper cover; a reference electrode, a counter electrode, a glass fiber tape and a support plate are provided in sequence from top to bottom between the working electrode of the electrochemical hydrogen cyanide gas sensor and the shell; absorbent cotton is provided between the working electrode of the electrochemical hydrogen cyanide gas sensor and the reference electrode, between the reference electrode and the counter electrode, and below the support plate.

[0016] Furthermore, the support plate is provided with a plurality of through holes extending in the up-down direction, the glass fiber tape is in a U-shape, and the glass fiber tape passes through the through holes of the support plate.

[0017] Beneficial effects of the present invention:

[0018] The slurry of the working electrode of the electrochemical hydrogen cyanide gas sensor of the present invention is easy to configure and convenient to brush, and can be automatically brushed in large quantities. The electrochemical hydrogen cyanide gas sensor of the present invention can be carried by the user or placed in a location where hydrogen cyanide gas leakage may occur, making it convenient to carry.

[0019] During the drying process of the working electrode of the present invention, a small temperature gradient will be formed between the surface and interior temperatures of the working electrode, and the surface temperature of the working electrode will be higher than the internal temperature. During the drying process, the surface of the working electrode is dried first, and the concentration of substances on the surface is higher than the concentration of substances inside. Under such a driving force, the binder in the working electrode will gradually migrate to the surface as the water evaporates, and precipitate on the surface of the nanomaterial and the conductive agent, thereby affecting the pore structure and binder distribution of the working electrode, thereby affecting the performance of the electrochemical hydrogen cyanide sensor. If the drying temperature of the working electrode is too high, the structure of the graphite may be destroyed, resulting in a decrease in its performance. If the drying temperature of the working electrode is too low, the moisture in the graphite cannot be effectively removed, which may affect its electrical conductivity and thermal conductivity.

[0020] The electrochemical hydrogen cyanide gas sensor working electrode of the present invention can significantly improve the sensitivity and response speed of the electrochemical hydrogen cyanide gas sensor. This is because the conductive material increases the surface area of ​​the working electrode, increasing active sites and promoting charge transfer and reaction kinetics. The porous structure of the conductive material provides abundant transmission channels, promoting ion diffusion and electrolyte infiltration, enabling rapid electron transmission, reducing polarization and ohmic losses, and improving the performance of the electrochemical hydrogen cyanide gas sensor. The polytetrafluoroethylene emulsion forms hydrophobic pores, providing channels for the diffusion of hydrogen cyanide gas within the silver nanomaterial catalytic layer, accelerating the entry of hydrogen cyanide gas into the silver nanomaterial catalytic layer, allowing the silver nanomaterial catalytic layer to quickly react with hydrogen cyanide gas to produce a signal. Once the hydrogen cyanide gas disappears, the electrochemical hydrogen cyanide gas sensor reading quickly returns to 0, facilitating instrument operation.

[0021] The working electrode of the electrochemical hydrogen cyanide gas sensor of the present invention can catalyze an oxidation reaction of the hydrogen cyanide gas sensor on its surface, and the binder plays a bonding role, so that the silver nanomaterial, graphite and polytetrafluoroethylene film are firmly combined, effectively reducing the shedding of the silver nanomaterial and graphite and improving durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 1 is a structural diagram of the electrochemical hydrogen cyanide gas sensor in Example 1;

[0023] Figure 2 The figures are the physical pictures of the slurries in Comparative Example 3 and Example 1;

[0024] Figure 3 Graph showing the performance of the electrochemical hydrogen cyanide gas sensor in Examples 1-3 and Comparative Example 1;

[0025] Figure 4 Graph showing the performance of the electrochemical hydrogen cyanide gas sensor in Example 1 and Comparative Example 2;

[0026] Figure 5Graphs showing the performance of the electrochemical hydrogen cyanide gas sensors in Example 1 and Comparative Examples 4-5.

[0027] Figure 1 Middle: 1. Metal pin; 2. Shell; 3. Support plate; 4. Fiberglass tape; 5. Counter electrode; 6. Reference electrode; 7. Working electrode; 8. Absorbent cotton; 9. Upper cover; 10. Air inlet. DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to the embodiments of the present invention and the accompanying drawings.

[0029] Polytetrafluoroethylene emulsion was purchased from DuPont.

[0030] Example 1

[0031] The method for preparing the working electrode of the electrochemical hydrogen cyanide gas sensor of Example 1 comprises the following steps:

[0032] 1) Add a binder to water at 60°C and stir until the binder is completely dissolved to form a transparent solution with a certain viscosity to obtain a binder solution. The binder solution has a mass fraction of 2%. The binder is a perfluorosulfonic acid polymer solution, and the solid content of the perfluorosulfonic acid polymer solution is 20%.

[0033] 2) Mix 0.2 mL of binder solution, 0.2 mL of polytetrafluoroethylene (PTFE) emulsion, 0.2 g of silver nanomaterial, and 0.03 g of graphite in an automatic vacuum mixer for 3 minutes to form a slurry with brushable viscosity. Transfer the slurry to a screen printer and brush onto a polytetrafluoroethylene film to prepare a working electrode. Bake the brushed working electrode at 200°C for 1 hour and flatten it using a press. The solids content of the polytetrafluoroethylene emulsion is 30%.

[0034] The electrochemical hydrogen cyanide gas sensor of Example 1 comprises a housing 2 with an open top. An upper cover 9 is enclosed within the housing, and an air inlet 10 is provided in the upper portion of the housing. A metal pin 1 is connected to the lower end of the housing 2 for connection to the alarm test board. Disposed between the housing 2 and the upper cover 9, from top to bottom, are the electrochemical hydrogen cyanide gas sensor working electrode 7, reference electrode 6, counter electrode 5, glass fiber tape 4, and support plate 3 of Example 1. A 17 mm diameter absorbent cotton pad is positioned between the working electrode 7 and reference electrode 6, between the reference electrode 6 and counter electrode 5, and below the support plate 4. The support plate 3 is provided with several vertically extending through-holes. The glass fiber tape 4 is U-shaped and passes through the through-holes of the support plate 3.

[0035] Example 2

[0036] The method for preparing the working electrode of the electrochemical hydrogen cyanide gas sensor of Example 2 comprises the following steps:

[0037] 1) Add a binder to water at 100°C and stir until the binder is completely dissolved to form a transparent solution with a certain viscosity to obtain a binder solution having a mass fraction of 4%. The binder is a perfluorosulfonic acid polymer solution having a solid content of 20%.

[0038] 2) Mix 0.2 mL of binder solution, 0.2 mL of polytetrafluoroethylene (PTFE) emulsion, 0.2 g of silver nanomaterial, and 0.03 g of graphite in an automatic vacuum mixer for 3 minutes to form a slurry with brushable viscosity. Transfer the slurry to a screen printer and brush onto a polytetrafluoroethylene film to prepare a working electrode. The brushed working electrode is baked at 150°C for 1 hour and finally flattened using a press. The solids content of the polytetrafluoroethylene emulsion is 40%.

[0039] The structure of the electrochemical hydrogen cyanide gas sensor of Example 2 is the same as that of Example 1.

[0040] Example 3

[0041] The method for preparing the working electrode of the electrochemical hydrogen cyanide gas sensor of Example 3 comprises the following steps:

[0042] 1) Add a binder to water at 80°C and stir until the binder is completely dissolved to form a transparent solution with a certain viscosity to obtain a binder solution. The binder solution has a mass fraction of 2%. The binder is a perfluorosulfonic acid polymer solution, and the solid content of the perfluorosulfonic acid polymer solution is 20%.

[0043] 2) Mix 0.2 mL of binder solution, 0.3 mL of polytetrafluoroethylene (PTFE) emulsion, 0.2 g of silver nanomaterial, and 0.03 g of graphite in an automatic vacuum mixer for 3 minutes to form a slurry with brushable viscosity. Transfer the slurry to a screen printer and brush onto a polytetrafluoroethylene film to prepare a working electrode. The brushed working electrode is baked at 250°C for 1 hour and then flattened using a press. The solids content of the polytetrafluoroethylene emulsion is 30%.

[0044] The structure of the electrochemical hydrogen cyanide gas sensor of Example 3 is the same as that of Example 1.

[0045] Example 4

[0046] The method for preparing the working electrode of the electrochemical hydrogen cyanide gas sensor of Example 4 comprises the following steps:

[0047] 1) Add a binder to water at 80° C. and stir until the binder is completely dissolved to form a transparent solution with a certain viscosity to obtain a binder solution. The binder solution has a mass fraction of 2%. The binder is ethyl cellulose.

[0048] 2) Mix 0.2 mL of binder solution, 0.3 mL of polytetrafluoroethylene (PTFE) emulsion, 0.4 g of silver nanomaterial, and 0.03 g of graphite in an automatic vacuum mixer for 3 minutes to form a slurry with brushable viscosity. Transfer the slurry to a screen printer and brush onto a polytetrafluoroethylene film to prepare a working electrode. Bake the brushed working electrode at 200°C for 1 hour and flatten it using a press. The solids content of the polytetrafluoroethylene emulsion is 30%.

[0049] The structure of the electrochemical hydrogen cyanide gas sensor of Example 4 is the same as that of Example 1.

[0050] Example 5

[0051] The method for preparing the working electrode of the electrochemical hydrogen cyanide gas sensor of Example 5 comprises the following steps:

[0052] 1) Add the binder to water at 80° C. and stir until the binder is completely dissolved to form a transparent solution with a certain viscosity to obtain a binder solution. The mass fraction of the binder solution is 2%. The binder is polyacrylic acid.

[0053] 2) Mix 0.2 mL of binder solution, 0.3 mL of polytetrafluoroethylene (PTFE) emulsion, 0.3 g of silver nanomaterial, and 0.03 g of graphite in an automatic vacuum mixer for 3 minutes to form a slurry with brushable viscosity. Transfer the slurry to a screen printer and brush onto a polytetrafluoroethylene film to prepare a working electrode. Bake the brushed working electrode at 200°C for 1 hour and flatten it using a press. The solids content of the polytetrafluoroethylene emulsion is 30%.

[0054] The structure of the electrochemical hydrogen cyanide gas sensor of Example 5 is the same as that of Example 1.

[0055] Comparative Example 1

[0056] The preparation method of the working electrode of the electrochemical hydrogen cyanide gas sensor of Comparative Example 1 includes the following steps: 2 g of carbon powder, 1 g of silver nanoparticles, 10 mL of ethanol, and 5 mL of propylene glycol solution are placed in a tank and ball-milled on a ball mill for 30 to 50 minutes to obtain a slurry, the slurry is heated and boiled into a viscous state, and after cooling, it is brushed on a polytetrafluoroethylene film to obtain a working electrode, and the brushed working electrode is baked at a temperature of 150°C for 1 hour and flattened with a press.

[0057] The structure of the electrochemical hydrogen cyanide gas sensor of Comparative Example 1 is the same as that of Example 1.

[0058] Comparative Example 2

[0059] The preparation method of the working electrode of the electrochemical hydrogen cyanide gas sensor of Comparative Example 2 is substantially the same as that of Example 1. The difference between the preparation method of the working electrode of the electrochemical hydrogen cyanide gas sensor of Comparative Example 2 and Example 1 is that the preparation method of the working electrode of the electrochemical hydrogen cyanide gas sensor of Comparative Example 2 does not add the conductive agent graphite.

[0060] The structure of the electrochemical hydrogen cyanide gas sensor of Comparative Example 2 is the same as that of Example 1.

[0061] Comparative Example 3

[0062] The preparation method of the electrochemical hydrogen cyanide gas sensor working electrode of Comparative Example 3 comprises the following steps:

[0063] 1) Add the binder to water at 60° C. and stir until the binder is completely dissolved to form a transparent solution with a certain viscosity to obtain a binder solution. The binder solution has a mass fraction of 2%. The binder is a perfluorosulfonic acid polymer solution.

[0064] 2) 0.2 mL of binder solution, 0.2 mL of polytetrafluoroethylene emulsion, 0.2 g of silver nanomaterial, and 0.05 g of graphite were stirred in an automatic vacuum mixer for 3 min. The resulting slurry would clump and could not be brushed.

[0065] Comparative Example 4

[0066] The preparation method of the working electrode of the electrochemical hydrogen cyanide gas sensor of Comparative Example 4 is substantially the same as that of Example 1. The difference between the preparation method of the working electrode of the electrochemical hydrogen cyanide gas sensor of Comparative Example 4 and Example 1 is that the drying temperature of the working electrode of the electrochemical hydrogen cyanide gas sensor of Comparative Example 4 is 100°C.

[0067] Comparative Example 5

[0068] The preparation method of the working electrode of the electrochemical hydrogen cyanide gas sensor of Comparative Example 5 is roughly the same as that of Example 1. The difference between the preparation method of the working electrode of the electrochemical hydrogen cyanide gas sensor of Comparative Example 5 and Example 1 is that the drying temperature of the working electrode of the electrochemical hydrogen cyanide gas sensor of Comparative Example 5 is 300°C.

[0069] from Figure 3 It can be seen that the response signal T90 of the hydrogen cyanide electrochemical sensor of Example 1 is 15s, which is significantly shorter than the T90 of 75s of the hydrogen cyanide electrochemical sensor in Comparative Example 1. Moreover, the signal can quickly recover to 0 after the hydrogen cyanide gas is removed, indicating that the working electrode of the electrochemical hydrogen cyanide gas sensor of the present invention can significantly improve the performance of the hydrogen cyanide sensor. Figure 4It can be seen that the conductive material added during the preparation of the working electrode of the electrochemical hydrogen cyanide gas sensor of Example 1 can greatly improve the sensitivity and response speed of the electrochemical hydrogen cyanide gas sensor.

Claims

1. A method for preparing a working electrode of an electrochemical hydrogen cyanide gas sensor, characterized in that: The method comprises the following steps: mixing a binder solution, a polytetrafluoroethylene emulsion, a nano material and a conductive agent to obtain a slurry, brushing the slurry on a waterproof breathable membrane, baking and pressing the membrane to obtain the slurry.

2. The method for preparing the working electrode of the electrochemical hydrogen cyanide gas sensor according to claim 1, characterized in that: The volume ratio of the binder solution to the polytetrafluoroethylene emulsion is 1:1-1.5, the mass fraction of the binder solution is 2-4%, and the solid content of the polytetrafluoroethylene emulsion is 30-60%.

3. The method for preparing a working electrode for an electrochemical hydrogen cyanide gas sensor according to claim 1, wherein: Each mL of the binder solution corresponds to adding 0.1 to 0.2 g of the nanomaterial, and each mL of the binder solution corresponds to adding 0.015 to 0.020 g of the conductive agent.

4. The method for preparing a working electrode for an electrochemical hydrogen cyanide gas sensor according to claim 1, wherein: The conductive agent is graphite; the nano material is silver nano material; the binder is one or more of perfluorosulfonic acid polymer solution, cellulose, and polyacrylic acid, and the solid content of the perfluorosulfonic acid polymer solution is 20-30%.

5. The method for preparing a working electrode for an electrochemical hydrogen cyanide gas sensor according to claim 1, wherein: The baking temperature is 150-250°C.

6. The method for preparing a working electrode for an electrochemical hydrogen cyanide gas sensor according to claim 1, wherein: The slurry is brushed onto the waterproof breathable membrane by screen printing, and the waterproof breathable membrane is a polytetrafluoroethylene membrane.

7. A working electrode for an electrochemical hydrogen cyanide gas sensor, characterized in that: The working electrode of the electrochemical hydrogen cyanide gas sensor is prepared by the preparation method of claim 1.

8. An electrochemical hydrogen cyanide gas sensor, characterized in that: The electrochemical hydrogen cyanide gas sensor working electrode comprises the electrochemical hydrogen cyanide gas sensor according to claim 7.

9. The electrochemical hydrogen cyanide gas sensor according to claim 8, characterized in that: It also includes a shell, which is hollow inside and has an open upper end; an upper cover is provided in the shell to seal the shell, and an air inlet is provided on the upper cover; a metal pin is connected to the lower end of the shell; the working electrode of the electrochemical hydrogen cyanide gas sensor is located below the upper cover; a reference electrode, a counter electrode, a glass fiber tape and a support plate are provided in sequence from top to bottom between the working electrode of the electrochemical hydrogen cyanide gas sensor and the shell; absorbent cotton is provided between the working electrode of the electrochemical hydrogen cyanide gas sensor and the reference electrode, between the reference electrode and the counter electrode, and below the support plate.

10. The electrochemical hydrogen cyanide gas sensor according to claim 9, characterized in that: The support plate is provided with a plurality of through holes extending in the up-down direction. The glass fiber tape is in a U-shape and passes through the through holes of the support plate.

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