Electrode material for electrochemical nitric oxide sensor, working electrode and electrochemical nitric oxide sensor

Abstract

This invention provides an electrode material, a working electrode, and an electrochemical nitric oxide sensor for use in an electrochemical nitric oxide sensor, relating to the technical field of detection elements. The electrode material for the electrochemical nitric oxide sensor includes a catalyst applied to an electrode substrate and a first water-retaining agent; wherein the first water-retaining agent includes one or more of SiO2, PVP, CMC, PVA, and PEG. The electrode material for the electrochemical nitric oxide sensor provided by this invention, by adding a first water-retaining agent (SiO2, PVP, CMC, PVA, PEG, etc.) to the electrode material, effectively improves the water retention capacity of the electrode material while improving the surface hydrophilicity of the nitric oxide oxidation catalyst, reducing electrolyte volatilization, thereby maintaining the long-term stability of the sensor in low-humidity environments and improving the sensor's lifespan in low-humidity environments.

Description

Technical Field

[0001] This invention relates to the field of detection element technology, and in particular to an electrode material, a working electrode, and an electrochemical nitric oxide sensor. Background Technology

[0002] The working principle of electrochemical gas sensors is mainly based on electrochemical reactions. When the analyte reacts with the sensitive electrode in the sensor, it will produce changes in electrical signals such as current, voltage or resistance. These changes are directly related to the concentration or properties of the analyte. By measuring these changes in electrical signals, quantitative or qualitative analysis of the analyte can be achieved.

[0003] Electrochemical gas sensors typically consist of a working electrode, an auxiliary electrode, a reference electrode, a counter electrode, and an electrolyte (or electrolyte solution). The working electrode is the primary site of the electrochemical reaction; its surface is usually coated with a catalyst material that selectively reacts with the analyte. The auxiliary electrode mitigates the effects of ambient temperature variations. The reference electrode provides a stable potential reference, ensuring measurement accuracy and stability. The counter electrode and working electrode form a current loop, jointly promoting the electrochemical reaction. The electrolyte serves as the medium for the electrochemical reaction, facilitating ion transport between the electrodes.

[0004] Electrochemical gas sensors rely on catalytic reactions on the surface of the working electrode to convert gas concentration into electrical signals. Their performance depends on a stable gas-liquid-solid three-phase interface (gas diffusion layer, liquid electrolyte, and catalytic electrode). However, in low humidity or high temperature environments, the electrolyte at the working electrode continues to evaporate, resulting in electrode drying. This disrupts the balance of the three-phase interface and has a series of adverse effects on the sensor's performance, such as sensitivity decay, baseline drift, and signal distortion. It can even cause physical damage to the electrode, greatly affecting the sensor's effective lifespan.

[0005] Existing electrochemical sensors generally face the problem of shortened lifespan under low humidity conditions.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] One of the objectives of this invention is to provide an electrode material for an electrochemical nitric oxide sensor, so as to at least solve one of the technical problems existing in the prior art.

[0008] The second objective of this invention is to provide an application of an electrode material for an electrochemical nitric oxide sensor in the preparation of a working electrode.

[0009] The third objective of this invention is to provide a working electrode.

[0010] The fourth objective of this invention is to provide an application of a working electrode in the fabrication of an electrochemical nitric oxide sensor.

[0011] The fifth objective of this invention is to provide an electrochemical nitric oxide sensor.

[0012] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides an electrode material for an electrochemical nitric oxide sensor, comprising: a catalyst and a first water-retaining agent applied to an electrode substrate; The first water-retaining agent includes one or more of SiO2, PVP, CMC, PVA, and PEG.

[0013] Furthermore, the catalyst is graphite.

[0014] Furthermore, the first water-retaining agent accounts for 0.1% to 30% of the total mass of the electrode material used in the electrochemical nitric oxide sensor; the catalyst accounts for 55% to 94.9% of the total mass of the electrode material used in the electrochemical nitric oxide sensor.

[0015] Furthermore, the first water-retaining agent includes hydrophilic fumed SiO2; Preferably, the first water-retaining agent accounts for 5%-15% of the total mass of the electrode material used in the electrochemical nitric oxide sensor.

[0016] Secondly, the present invention provides the application of an electrode material for an electrochemical nitric oxide sensor in the preparation of a working electrode.

[0017] Thirdly, the present invention provides a working electrode, comprising an electrode substrate and the electrode material described above for an electrochemical nitric oxide sensor.

[0018] Furthermore, it is prepared in the following manner: (a) Pretreatment: Mix the catalyst, the first water-retaining agent, and the binder; (b) Printing or pressing pretreated electrode materials for an electrochemical nitric oxide sensor onto an electrode substrate; Preferably, in step (a), the mixing method includes ball milling.

[0019] Fourthly, the present invention provides an application of a working electrode in the fabrication of an electrochemical nitric oxide sensor.

[0020] Fifthly, the present invention provides an electrochemical nitric oxide sensor, comprising: an electrode assembly; The electrode assembly includes a working electrode.

[0021] Furthermore, the electrode assembly also includes an auxiliary electrode, a reference electrode, and a counter electrode, wherein the working electrode, the auxiliary electrode, the reference electrode, and the counter electrode are stacked sequentially. Preferably, the material composition of the auxiliary electrode is the same as that of the working electrode; Preferably, the reference electrode comprises a reference electrode substrate and an electrode material; the electrode material of the reference electrode comprises platinum black. Preferably, the counter electrode comprises a counter electrode substrate and an electrode material; the electrode material of the counter electrode comprises platinum black. Preferably, the electrochemical nitric oxide sensor further includes an electrolyte in contact with the electrode assembly; Preferably, the electrolyte comprises sulfuric acid, a second water-retaining agent, and a surfactant; Preferably, the electrolyte comprises, by mass percentage: 1%~8% second water-retaining agent, 0.01%~0.1% surfactant, and 91.9%-98.99% sulfuric acid; Preferably, the sulfuric acid concentration is 5-6 mol / L; Preferably, the second water-retaining agent is hydrophilic fumed SiO2; Preferably, the surfactant is selected from one or more of hydrocarbon chain surfactants and fluorinated surfactants; the hydrocarbon chain surfactant is selected from one or more of anionic hydrocarbon chain surfactants and nonionic hydrocarbon chain surfactants; the anionic hydrocarbon chain surfactant is selected from one or more of alkyl sulfates, alkylbenzene sulfonates and alkyl carboxylates; the nonionic hydrocarbon chain surfactant is selected from one or more of polyoxyethylene alkyl ethers and polyoxyethylene alkyl aryl ethers; and the fluorinated surfactant is selected from one or more of perfluoroalkyl sulfonates.

[0022] Compared with the prior art, the present invention has the following beneficial effects: The electrode material for an electrochemical nitric oxide sensor provided by this invention improves the water retention capacity of the electrode material by adding a first water-retaining agent (SiO2, PVP, CMC, PVA, PEG, etc.) to the electrode material, thereby reducing the evaporation of the electrolyte and maintaining the long-term stability of the sensor in a low-humidity environment, while also improving the lifespan of the sensor in a low-humidity environment.

[0023] This invention provides an electrochemical nitric oxide sensor, wherein the working electrode is prepared using electrode materials used in electrochemical nitric oxide sensors. By optimizing the material formulation in the working electrode, the long-term reliability of the sensor performance is ensured under different environmental conditions (especially in low humidity environments), and it has the advantages of good environmental adaptability and long effective service life. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the overall structure of the electrochemical nitric oxide sensor provided by the present invention; Figure 2 This is a structural diagram of the top cover, base, and liquid storage box; Figure 3 An exploded view of an electrochemical nitric oxide sensor; Figure 4 This is a cross-sectional view of an electrochemical nitric oxide sensor. Figure 5 This is a schematic diagram of the upper cover structure; Figure 6 This is a schematic diagram of the structure of the breathable partition; Figure 7 This is a schematic diagram of the liquid storage box. Figure 8 This is a schematic diagram of the liquid storage box from another angle; Figure 9 This is a schematic diagram of the liquid storage box and pins; Figure 10 This is a schematic diagram of the support frame.

[0026] Icons: 1-Top cover; 10-Air inlet; 11-Dustproof membrane; 12-Second annular protrusion; 13-Annular stepped surface; 2-Base; 3-Liquid storage box; 30-Receiving groove; 31-First seal; 32-First clearance groove; 33-Second clearance groove; 34-Injection port; 340-Sealing pin; 35-Limiting post; 36-Annular boss; 4-Electrode assembly; 40-Working electrode; 41-Auxiliary electrode; 42-Counter electrode; 43-Reference electrode; 44-Liquid absorption membrane; 45-Liquid retaining ring; 46-Liquid absorption strip; 47-Connecting membrane; 5-Pin; 50-Guide wire; 6-Ventilating partition; 60-Ventilating hole; 61-Rib; 7-Selective filter layer; 8-Second seal; 9-Support frame; 90-Liquid permeation hole; 91-Reinforcing rib; 92-Limiting groove. Detailed Implementation

[0027] Unless otherwise defined herein, the scientific and technical terms used in conjunction with this invention shall have the meanings commonly understood by one of ordinary skill in the art. The meaning and scope of terms shall be clear; however, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or foreign definitions. In this application, unless otherwise stated, the use of "or" means "and / or". Furthermore, the use of the term "comprising" and other forms is non-limiting.

[0028] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0029] A first aspect of the present invention provides an electrode material for an electrochemical nitric oxide sensor, comprising: a catalyst applied to an electrode substrate and a first water-retaining agent; wherein the first water-retaining agent comprises one or more of SiO2, PVP, CMC, PVA and PEG.

[0030] The electrode material for an electrochemical nitric oxide sensor provided by this invention effectively enhances the water retention capacity of the electrode material by introducing a first water-retaining agent into the electrode material, thereby improving the hydrophilicity of the catalyst surface and bringing about the following multiple technical effects: 1. Significantly improves the hydrophilicity of electrode materials: The introduction of water-retaining agents enhances the interfacial wettability between electrode materials and electrolytes, allowing the electrolyte to penetrate more evenly to the catalyst surface, thereby improving electrode reaction efficiency and response sensitivity.

[0031] 2. Effectively suppresses electrolyte evaporation and extends sensor lifespan: In low-humidity or dry environments, traditional electrode materials are prone to sensor performance degradation or even failure due to rapid electrolyte evaporation. This invention, through the hygroscopic and water-retaining properties of the water-retaining agent, can significantly reduce the evaporation rate of the electrolyte, thereby maintaining the long-term stability of the sensor in low-humidity environments.

[0032] In some preferred embodiments, the catalyst is graphite. The catalyst is reactive with nitric oxide gas.

[0033] In some preferred embodiments, the first water-retaining agent accounts for 0.1% to 30% of the total mass of the electrode material used in the electrochemical nitric oxide sensor; the catalyst accounts for 55% to 94.9% of the total mass of the electrode material used in the electrochemical nitric oxide sensor.

[0034] In this case, taking the total mass of the electrode material used in the electrochemical nitric oxide sensor as 100%, the amount of the first water-retaining agent added is 0.1% to 30%, for example, it can be 0.1%, 0.5%, 1%, 1.5%, 5%, 10%, 15%, 20%, 25%, 30%, etc.

[0035] In this case, taking the total mass of the electrode material used in the electrochemical nitric oxide sensor as 100%, the amount of catalyst used is 55%-94.9%, for example, it can be 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 94.9%, etc.

[0036] Optionally, the electrode material for the electrochemical nitric oxide sensor further includes a binder. The amount of binder added is 5% to 15% based on the total mass of the electrode material for the electrochemical nitric oxide sensor being 100%, for example, it can be 5%, 10%, 15%, etc.

[0037] In some preferred embodiments, the first water-retaining agent is further preferably a hydrophilic vapor-phase SiO2.

[0038] More preferably, the first water-retaining agent accounts for 5% to 15% of the total mass of the electrode material used in the electrochemical nitric oxide sensor, for example, it can be 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, etc.

[0039] A second aspect of the present invention provides the application of an electrode material for an electrochemical nitric oxide sensor in the preparation of a working electrode.

[0040] A third aspect of the present invention provides a working electrode, comprising an electrode substrate and the electrode material described above for an electrochemical nitric oxide sensor.

[0041] In some preferred embodiments, the working electrode is prepared by the following method: (a) Pretreatment: Mix the catalyst, the first water-retaining agent, and the binder; (b) Printing or pressing pretreated electrode material for an electrochemical nitric oxide sensor onto an electrode substrate; wherein the electrode material can be printed / pressed onto the electrode substrate by adding a binder (such as a perfluorinated ion solution or a polytetrafluoroethylene emulsion).

[0042] Preferably, in step (a), the mixing method includes ball milling.

[0043] In this invention, the pretreatment of the electrode material can be carried out using either a dry process or a wet process. For example, graphite, hydrophilic fumed silica, binder, and solvent (ethylene glycol) can be placed in a ball mill jar and ground thoroughly at a speed of 200-600 rpm, preferably 400 rpm, for 20-60 minutes, preferably 40 minutes, to ensure thorough mixing of the materials. The grinding process increases the specific surface area of ​​the material, increases the number of active reaction sites, and improves the sensitivity of the sensor.

[0044] In this invention, hydrophilic fumed silica is added to the graphite electrode. This improves the hydrophilicity of the graphite electrode while locking in moisture, reducing electrolyte evaporation at the working electrode, thereby improving the sensor's lifespan in low-humidity environments. Furthermore, this solution also adds hydrophilic fumed silica to the electrolyte to further slow down the electrolyte evaporation rate.

[0045] The fourth aspect of the present invention provides the application of a working electrode in the fabrication of an electrochemical nitric oxide sensor.

[0046] The fifth aspect of the present invention provides an electrochemical nitric oxide sensor for detecting the concentration of nitric oxide in a gas to be tested. The electrochemical nitric oxide sensor includes an electrode assembly, wherein the electrode assembly includes the working electrode.

[0047] In some preferred embodiments, the electrode assembly further includes an auxiliary electrode, a reference electrode, and a counter electrode, wherein the working electrode, the auxiliary electrode, the reference electrode, and the counter electrode are stacked sequentially.

[0048] Based on the above embodiments, and further preferably, in order to enhance the ability of the electrolyte to be conducted to the working electrode and other electrodes, thereby alleviating the problem of the working electrode and other electrodes being prone to drying, the electrode assembly also includes an absorbent membrane. An absorbent membrane is arranged between the working electrode and the auxiliary electrode, between the auxiliary electrode and the counter electrode, and between the counter electrode and the reference electrode. The absorbent membrane can be made of materials such as glass fiber membrane, and is used to adsorb the electrolyte and keep it moist, so as to better wet the electrodes.

[0049] Preferably, the material composition of the auxiliary electrode is the same as that of the working electrode; Preferably, the reference electrode comprises a reference electrode substrate and an electrode material; the electrode material of the reference electrode comprises platinum black.

[0050] The electrode substrate of each electrode in this invention is a hydrophobic and breathable substrate, which can be made of PTFE material.

[0051] Preferably, the counter electrode comprises a counter electrode substrate and an electrode material; the electrode material of the counter electrode comprises platinum black.

[0052] In this invention, each electrode is composed of a substrate and an electrode material formed on the substrate.

[0053] Preferably, the electrochemical nitric oxide sensor further includes an electrolyte; Preferably, the electrolyte is in contact with the electrode assembly; Preferably, the electrolyte comprises sulfuric acid, a second water-retaining agent, and a surfactant; In this invention, a certain amount of surfactant is added to the electrolyte to improve the surface tension of the electrolyte, increase the wettability of the electrolyte, and enable the electrolyte to be effectively conducted into the electrode material to form a uniform and stable solid-liquid interface, thereby improving the reaction rate of the target gas on the electrode. Furthermore, the addition can significantly reduce the surface tension of the electrolyte and increase its wettability, which helps to ensure the performance of the sensor in low humidity environments.

[0054] Preferably, the electrolyte comprises, by mass percentage: 1% to 8% of a second water-retaining agent, 0.01% to 0.1% of a surfactant, and the balance being a sulfuric acid solution.

[0055] The total mass of the electrolyte is 100%, and the amount of the second water-retaining agent added is 1% to 8%, for example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, etc. The total mass of the electrolyte is 100%, and the amount of surfactant added is 0.01% to 0.1%, for example, it can be 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, etc.

[0056] Preferably, the second water-retaining agent comprises SiO2; more preferably, it comprises gaseous SiO2.

[0057] Preferably, the sulfuric acid concentration is 5-6 mol / L.

[0058] Preferably, the second water-retaining agent is hydrophilic fumed SiO2; Preferably, the surfactant is selected from one or more of hydrocarbon chain surfactants and fluorinated surfactants; the hydrocarbon chain surfactant is selected from one or more of anionic hydrocarbon chain surfactants and nonionic hydrocarbon chain surfactants; the anionic hydrocarbon chain surfactant is selected from one or more of alkyl sulfates, alkylbenzene sulfonates and alkyl carboxylates; the nonionic hydrocarbon chain surfactant is selected from one or more of polyoxyethylene alkyl ethers and polyoxyethylene alkyl aryl ethers; and the fluorinated surfactant is selected from one or more of perfluoroalkyl sulfonates.

[0059] The structure and composition of the electrochemical nitric oxide sensor are described in detail below.

[0060] Regarding the composition and shape structure of the electrochemical nitric oxide sensor, specifically: The electrochemical nitric oxide sensor includes an electrode assembly 4, which comprises a working electrode 40, an auxiliary electrode 41, a counter electrode 42, and a reference electrode 43 stacked sequentially. The electrode assembly 4 also includes several absorbent membranes 44 arranged between the electrodes. The working electrode 40 is located at a relatively far end from the electrolyte, making it prone to drying in low humidity or high temperature environments. The arrangement of the absorbent membranes 44 in this invention enhances the electrolyte's ability to conduct to the working electrode 40, thereby alleviating the problem of the working electrode 40 drying out easily.

[0061] Electrochemical nitric oxide sensor, such as Figure 1 , Figure 2 and Figure 3 As shown, it also includes a top cover 1, a base 2, a liquid storage box 3, and pins 5.

[0062] The upper cover 1 has an air inlet 10 in the middle, and the base 2 has an opening at the top. The upper cover 1 and the base 2 are connected by a snap-fit ​​structure. The liquid storage box 3 is at least partially placed in the base 2. The top of the liquid storage box 3 is open and is used to hold at least the electrolyte. A circumferential receiving groove 30 is formed on the top end face of the liquid storage box 3. The receiving groove 30 contains a first sealing element 31. When the upper cover 1 and the base 2 are closed, the first sealing element 31 is press-fitted with the inner surface of the upper cover 1. The electrode assembly 4 is placed in the space between the liquid storage box 3 and the upper cover 1. There are several pins 5, all of which extend through the bottom surface of the base 2. The pins 5 are connected to the electrodes of the electrode assembly 4 through guide wires 50.

[0063] refer to Figure 2 and Figure 5 A groove is formed on the inner side of the top cover 1, and a corresponding buckle is formed on the outer side of the base 2. After the top cover 1 is fastened to the base 2, the groove and the buckle engage. The groove and the buckle can be formed on the inner or outer side of the top cover 1, or on the inner or outer side of the base 2, without limitation. The top cover 1 and the base 2 can be made of materials such as ABS, PC, or ABS+PC through injection molding. The top cover 1 and the base 2 made in this way are resistant to electrolyte corrosion and have good toughness, making them less prone to cracking during installation.

[0064] refer to Figure 2 and Figure 7After the upper cover 1 and the base 2 are connected, the first sealing element 31 on the top end face of the liquid storage box 3 is press-fitted with the inner surface of the upper cover 1, thereby achieving a sealing effect and preventing the electrolyte in the liquid storage box 3 from leaking into the gap between the upper cover 1 and the base 2. The snap-fit ​​connection, combined with the sealing ring, avoids complex processes such as hot melting and ultrasonic welding, prevents electrode breakage, improves product yield, reduces unit cost, and effectively reduces the occurrence of leakage problems.

[0065] The gas to be tested enters the sensor through the air inlet 10 at the top cover 1, and then comes into contact with the electrodes and electrolyte to undergo an electrochemical reaction.

[0066] Furthermore, such as Figure 3 As shown, the electrochemical nitric oxide sensor also includes a support frame 9, which is placed in the liquid storage box 3, and the electrode assembly 4 is placed on the support frame 9.

[0067] Furthermore, a through hole is provided in the middle of the support frame 9 along the axial direction; liquid permeable holes 90 are provided on the top and side surfaces of the support frame 9.

[0068] For details, please refer to Figure 3 and Figure 10 The support frame 9 supports the electrode assembly 4 above the electrolyte, ensuring that the electrode assembly 4 is not directly immersed in the electrolyte within the storage tank 3, thus reducing electrolyte evaporation and consumption. The permeable holes 90 on the support frame 9 facilitate electrolyte flow. Specifically, several reinforcing ribs 91 are formed on the top surface of the support frame 9, arranged circumferentially along the top surface to enhance structural strength. (Reference) Figure 7 and Figure 10 A limiting groove 92 is provided on the side of the support frame 9, which, together with the limiting post 35 in the liquid storage box 3, limits the position of the support frame 9 after installation.

[0069] The electrode assembly 4 also includes a liquid-retaining ring 45, which is arranged below the reference electrode 43. The liquid-retaining ring 45 has an opening in the middle, and a liquid-absorbing membrane 44 is also arranged between the liquid-retaining ring 45 and the reference electrode 43.

[0070] For details, please refer to Figure 3 and Figure 4 The liquid-retaining ring 45 can be made of materials such as PTFE to prevent a large amount of electrolyte from directly contacting the electrode assembly 4. The electrolyte only has the opportunity to contact the electrode assembly 4 after passing through the opening in the middle of the liquid-retaining ring 45. Further, refer to... Figure 7 An annular protrusion 36 is formed inside the liquid storage box 3. The height of the annular protrusion 36 is equivalent to the height of the top surface of the support frame 9 after the support frame 9 is placed. By sealing the liquid-blocking ring 45 with the annular protrusion 36, the electrolyte can be further prevented from overflowing into the electrode assembly 4 from the gap. This can further reduce the improper consumption of electrolyte and increase the effective service life of the sensor in high temperature and low humidity environments.

[0071] Furthermore, the electrode assembly 4 also includes a liquid-absorbing strip 46, one end of which is arranged in the through hole in the middle of the support frame 9 and in contact with the electrolyte, and the other end passes through the opening in the middle of the liquid-blocking ring 45 and contacts the liquid-absorbing membrane 44 between the liquid-blocking ring 45 and the reference electrode 43.

[0072] For details, please refer to Figure 3 and Figure 4 One end of the absorbent strip 46 is immersed in the electrolyte, and the other end contacts the absorbent membrane 44 below the reference electrode 43. The absorbent strip 46 can also be made of materials such as glass fiber membrane. The absorbent strip 46 can effectively guide the electrolyte from the reservoir 3 to the absorbent membrane 44 of the electrode assembly 4, and then guide it to each electrode through each absorbent membrane 44. On the one hand, this ensures that each electrode is wetted. On the other hand, in conjunction with the liquid-retaining ring 45 and the arrangement of the electrode assembly 4, it can realize the on-demand consumption of electrolyte, reduce electrolyte loss and evaporation, and thus maintain the wetting environment at the working electrode for a long time.

[0073] Furthermore, the auxiliary electrode 41 is annular with an opening in the middle; the electrode assembly 4 also includes a connecting membrane 47, which fills the opening in the middle of the auxiliary electrode 41.

[0074] For details, please refer to Figure 4 The connecting membrane 47 can also be made of materials such as glass fiber membrane. By setting the connecting membrane 47, the ability of the distal end of the electrode assembly 4 to be wetted with electrolyte can be further enhanced, thereby further alleviating the problem of the working electrode 40 drying out easily.

[0075] Specifically, by adding a hydrophilic vapor-phase SiO2 water-retaining agent to the electrolyte, the evaporation of water in the electrolyte can be effectively slowed down. Combined with the series of structures such as the liquid-absorbing membrane 44, the connecting membrane 47, and the liquid-absorbing strip 46 in the electrode assembly 4, the electrolyte that is guided to the working electrode 40 as needed can be effectively retained, thereby maintaining the humidity balance at the working electrode for a long time. This effectively solves the problem of the working electrode 40 of the electrochemical sensor drying out easily under high temperature and low humidity conditions.

[0076] Furthermore, it also includes a ventilated baffle 6, which is placed between the electrode assembly 4 and the upper cover 1. The ventilated baffle 6 is directly opposite the air inlet 10, and a plurality of ventilated holes 60 are formed on the ventilated baffle 6. The inner diameter of the ventilated holes 60 gradually decreases from the top to the bottom.

[0077] For details, please refer to Figure 3 , Figure 4 and Figure 6The gas to be tested passes through the air inlet 10 and then through the air vent 60 on the air vent 6 to contact the electrode. The inner diameter of the air vent 60 gradually decreases from the top to the bottom. This is beneficial for the infiltration of external ambient gas and the uniform distribution of gas. On the other hand, the smaller diameter end of the air vent 60 on the air vent 6 can be tightly pressed against the electrode assembly 4 and the air intake can be controlled. It can also reduce the evaporation of electrolyte moisture at the top electrode.

[0078] Further reference Figure 5 It also includes a dustproof membrane 11, which covers the air inlet 10. Specifically, an annular stepped surface 13 is formed on the outer surface of the air inlet 10 of the upper cover 1, and the dustproof membrane 11 can be bonded to the annular stepped surface 13 by waterproofing methods such as adhesive bonding. The dustproof membrane 11 can be made of non-woven fabric or non-woven fabric / PTFE composite membrane, etc., and is used to filter particulate matter to prevent particulate matter in the gas from entering the electrode or electrolyte through the air inlet 10 and affecting the detection. By bonding the dustproof membrane 11 to the annular stepped surface 13, the airtightness can be ensured, thereby effectively isolating and filtering large particulate impurities in the gas passing through the air inlet 10.

[0079] Further reference Figure 2 , Figure 3 and Figure 4 It also includes a selective filter layer 7, which is placed between the breathable partition 6 and the upper cover 1. The selective filter layer 7 is used to selectively filter or adsorb gas components passing through the air inlet 10. For example, taking an electrochemical sensor for nitric oxide detection as an example, the selective filter layer 7 can be made of carbon cloth. The carbon cloth can adsorb and treat components such as sulfides and carbon monoxide in the intake air to avoid affecting the detection of nitric oxide components in the intake air.

[0080] Further reference Figure 3 and Figure 6 The top surface of the breathable partition 6 has raised ribs 61 circumferentially formed. The raised ribs 61 can compress the selective filter layer 7, ensuring that there is no air leakage on the outer circumference, thereby improving the selective filtration effect.

[0081] Further reference Figure 3 and Figure 5 The top bottom surface of the cover 1 has a second annular protrusion 12. The outer side of the venting baffle 6 is press-fitted with the inner side of the second annular protrusion 12, thereby preventing gas and electrolyte from overflowing from the gap between the venting baffle 6 and the inner surface of the cover 1.

[0082] Further reference Figure 3 and Figure 4 It also includes a second seal 8, which is placed between the electrode assembly 4 and the upper cover 1. The second seal 8 is interference-fitted with both the electrode assembly 4 and the upper cover 1. By interfering with the electrode assembly 4, electrolyte leakage from the air inlet 10 of the upper cover 1 can be prevented.

[0083] Specifically, both the first seal 31 and the second seal 8 can be made of materials such as FKM.

[0084] Further reference Figure 3 , Figure 7 and Figure 8 The liquid storage box 3 has an injection port 34 on its side for filling with electrolyte. It also includes a sealing pin 340, which is interference-fitted with the injection port 34 to prevent electrolyte from overflowing from the injection port 34 after filling.

[0085] Further reference Figure 7 and Figure 9 The outer side of the liquid storage box 3 is recessed to form a plurality of first clearance grooves 32. The first clearance grooves 32 extend from the top to the bottom of the outer side of the liquid storage box 3. Each first clearance groove 32 is arranged circumferentially along the outer side of the liquid storage box 3. The first clearance grooves 32 are used to accommodate the guide wire 50.

[0086] Further reference Figure 8 and Figure 9 The bottom surface of the liquid storage box 3 is recessed to form several second clearance grooves 33, each of which corresponds to the top of each pin 5, and the second clearance grooves 33 are connected to the first clearance grooves 32.

[0087] The electrode materials and electrochemical nitric oxide sensor provided by the present invention will be further illustrated below through examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0088] In the following examples and comparative examples, the electrode substrates used for each electrode are all PTFE substrates.

[0089] Example 1 This embodiment provides an electrode material for an electrochemical nitric oxide sensor, which, by mass percentage, comprises 10% hydrophilic fumed silica, 80% graphite, and the balance binder (perfluorinated ion solution, with a solid content of 5% and N,N-dimethylformamide as the solvent).

[0090] Example 2 This embodiment provides an electrode material for an electrochemical nitric oxide sensor, which differs from Embodiment 1 in that its components include 5% hydrophilic fumed silica, 85% graphite, and the balance being a binder.

[0091] Example 3 This embodiment provides an electrode material for an electrochemical nitric oxide sensor, which differs from Embodiment 1 in that its components include 15% hydrophilic fumed silica, 75% graphite, and the balance being a binder.

[0092] Example 4 This embodiment provides an electrode material for an electrochemical nitric oxide sensor, which differs from Embodiment 1 in that its components include 0.1% hydrophilic fumed silica, 89.9% graphite, and the balance being a binder.

[0093] Example 5 This embodiment provides an electrode material for an electrochemical nitric oxide sensor, which differs from Embodiment 1 in that its components include 30% hydrophilic fumed silica, 60% graphite, and the balance binder.

[0094] Example 6 This embodiment provides an electrode material for an electrochemical nitric oxide sensor, which differs from Embodiment 1 in that its components include 0.05% hydrophilic fumed silica, 89.95% graphite, and the balance being a binder.

[0095] Example 7 This embodiment provides an electrode material for an electrochemical nitric oxide sensor, which differs from Embodiment 1 in that its composition includes 35% hydrophilic fumed silica, 55% graphite, and the balance being a binder.

[0096] Example 8 This embodiment provides an electrode material for an electrochemical nitric oxide sensor, which differs from Embodiment 1 in that PVP water-retaining agent is used instead of fumed silica water-retaining agent.

[0097] Examples 9-16 This embodiment provides a working electrode, including an electrode substrate and an electrode material, wherein the electrode material of the working electrode in embodiments 9-16 respectively adopts the electrode material of embodiments 1-8; The working electrode is prepared in the following manner: (1) Pretreatment: Place fumed silica, graphite and binder (perfluorine ion solution) in a ball mill jar and grind them thoroughly for 40 minutes at a speed of 400 rpm to ensure that the materials are fully mixed.

[0098] (2) The pretreated electrode material is printed on the PTFE substrate to obtain the working electrode.

[0099] Application Examples 1-8 This application example provides an electrochemical nitric oxide sensor, including an electrode assembly and an electrolyte in contact with the electrode assembly. The electrode assembly includes a working electrode, an auxiliary electrode, a counter electrode, and a reference electrode stacked in sequence. In Examples 1-8, the working electrodes are the working electrodes prepared in Examples 9-16, and the electrode material composition of the auxiliary electrode is the same as that of the working electrode. The reference electrode and the counter electrode are both composed of a substrate and an electrode material formed on the substrate. The electrode material of the reference electrode and the counter electrode are both platinum black. The platinum black is pressed onto the PTFE substrate by an adhesive (polytetrafluoroethylene emulsion) to obtain the reference electrode and the counter electrode.

[0100] The electrolyte is a sulfuric acid electrolyte, and its components, by mass percentage, include: 5% hydrophilic vapor-phase SiO2 water-retaining agent, 0.05% perfluoroalkyl sulfonate, and 94.95% 6 mol / L sulfuric acid.

[0101] Application Example 9 This application example provides an electrochemical nitric oxide sensor, which differs from Application Example 1 in that the electrolyte composition, by mass percentage, includes: 1% hydrophilic vapor-phase SiO2 water-retaining agent, 0.1% perfluoroalkyl sulfonate, and 98.9% 6 mol / L sulfuric acid.

[0102] Application Example 10 This application example provides an electrochemical nitric oxide sensor, which differs from Application Example 1 in that the electrolyte composition, by mass percentage, includes: 8% hydrophilic vapor-phase SiO2 water-retaining agent, 0.01% perfluoroalkyl sulfonate, and 91.99% 6 mol / L sulfuric acid.

[0103] Application Example 11 This application example provides an electrochemical nitric oxide sensor, which differs from Application Example 1 in that the electrolyte composition includes 0.05% hydrophilic vapor-phase SiO2 water-retaining agent, 0.05% perfluoroalkyl sulfonate, and the remainder sulfuric acid.

[0104] Application Example 12 This application example provides an electrochemical nitric oxide sensor, which differs from Application Example 1 in that the electrolyte composition includes 10% hydrophilic gaseous SiO2 water-retaining agent, 0.05% perfluoroalkyl sulfonate, and the remainder sulfuric acid.

[0105] Application Example 13 This application example provides an electrochemical nitric oxide sensor, which differs from Application Example 1 in that the electrolyte composition contains 0.005% surfactant alkyl sulfate, 5% hydrophilic vapor-phase SiO2 water-retaining agent, and the remainder sulfuric acid.

[0106] Application Example 14 This application example provides an electrochemical nitric oxide sensor, which differs from Application Example 1 in that the electrolyte composition contains 0.15% surfactant alkyl sulfate, 5% hydrophilic vapor-phase SiO2 water-retaining agent, and the remainder sulfuric acid.

[0107] Application Example 15 This application example provides an electrochemical nitric oxide sensor, which differs from Application Example 1 in that: no water-retaining agent is added to the electrolyte components, and the remaining amount is made up with sulfuric acid.

[0108] Application Example 16 This application example provides an electrochemical nitric oxide sensor, which differs from Application Example 1 in that: no surfactant is added to the electrolyte components, and the balance is made up with sulfuric acid.

[0109] Comparative Example 1 This comparative example provides an electrode material that differs from Example 1 in that no water-retaining agent is added to the electrode material components.

[0110] Comparative Example 2 This comparative example provides a working electrode, which differs from Example 9 in that the electrode material of the working electrode is the same as that of Comparative Example 1.

[0111] Comparative Application Example 1 This comparative application example provides an electrochemical nitric oxide sensor, which differs from application example 1 in that the working electrode is the working electrode prepared in comparative example 2.

[0112] Test case Test samples: Electrochemical nitric oxide sensors provided in Application Examples 1-16 and Comparative Application Example 1 were used.

[0113] Test method: The test conditions were 50℃ and 10%RH. The samples were tested on days 0, 1, 2, 4, 7, 14, 21 and 28. The gas concentration was 25 ppb of nitric oxide. There were 5 samples in each group, and the average value was taken after 5 consecutive measurements.

[0114] The test results are shown in Table 1.

[0115] Table 1

[0116] Table 1 shows that after aging tests at 50℃ / 10%RH for 28 days, with response readings measured using 25ppb standard gas, the results indicate that Application Example 1 (10% first water-retaining agent + 1% second water-retaining agent + 0.05% surfactant, all optimal values) achieved a signal retention rate of 94.0% after 28 days, demonstrating the best performance. Application Example 8, using PVP instead of SiO2 as the first water-retaining agent, achieved a retention rate of 88.4%, proving to be an effective alternative. When the first water-retaining agent was within the optimal range (Application Examples 2 and 3), the retention rate remained around 62%; however, when the first water-retaining agent deviated from the range (Application Examples 4 and 5), the retention rate dropped to 52%, indicating that the amount of the first water-retaining agent added is a key factor affecting sensor lifespan. Samples lacking key components (Application Examples 15, 16, and the comparative example) all showed retention rates below 28%, indicating significant degradation, further validating the important role of the synergistic ratio of the three additives in improving high-temperature and low-humidity stability.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrode material for an electrochemical nitric oxide sensor, characterized in that, include: Catalyst and first water-retaining agent applied to the electrode substrate; The first water-retaining agent includes one or more of SiO2, PVP, CMC, PVA, and PEG.

2. The electrode material for an electrochemical nitric oxide sensor according to claim 1, characterized in that, The catalyst is graphite.

3. The electrode material for an electrochemical nitric oxide sensor according to claim 1, characterized in that, The first water-retaining agent accounts for 0.1% to 30% of the total mass of the electrode material used in the electrochemical nitric oxide sensor; the catalyst accounts for 55% to 94.9% of the total mass of the electrode material used in the electrochemical nitric oxide sensor.

4. The electrode material for an electrochemical nitric oxide sensor according to claim 1, characterized in that, The first water-retaining agent includes hydrophilic vapor-phase SiO2; Preferably, the first water-retaining agent accounts for 5%-15% of the total mass of the electrode material used in the electrochemical nitric oxide sensor.

5. The application of the electrode material for an electrochemical nitric oxide sensor as described in any one of claims 1-4 in the preparation of the working electrode.

6. A working electrode, characterized in that, Includes an electrode substrate and the electrode material for an electrochemical nitric oxide sensor as described in any one of claims 1-4.

7. The working electrode according to claim 6, characterized in that, It is prepared in the following manner: (a) Pretreatment: Mix the catalyst, the first water-retaining agent, and the binder; (b) Printing or pressing pretreated electrode materials for an electrochemical nitric oxide sensor onto an electrode substrate; Preferably, in step (a), the mixing method includes ball milling.

8. The application of the working electrode as described in claim 6 or 7 in the fabrication of an electrochemical nitric oxide sensor.

9. An electrochemical nitric oxide sensor, characterized in that, include: Electrode assembly; The electrode assembly includes the working electrode as described in claim 6 or 7.

10. The electrochemical nitric oxide sensor according to claim 9, characterized in that, The electrode assembly further includes an auxiliary electrode, a reference electrode, and a counter electrode, wherein the working electrode, the auxiliary electrode, the reference electrode, and the counter electrode are stacked sequentially. Preferably, the material composition of the auxiliary electrode is the same as that of the working electrode; Preferably, the reference electrode comprises a reference electrode substrate and an electrode material; the electrode material of the reference electrode comprises platinum black. Preferably, the counter electrode comprises a counter electrode substrate and an electrode material; the electrode material of the counter electrode comprises platinum black. Preferably, the electrochemical nitric oxide sensor further includes an electrolyte in contact with the electrode assembly; Preferably, the electrolyte comprises sulfuric acid, a second water-retaining agent, and a surfactant; Preferably, the electrolyte comprises, by mass percentage: 1%~8% of a second water-retaining agent, 0.01%~0.1% of a surfactant, and 91.9%-98.99% of sulfuric acid; Preferably, the concentration of the sulfuric acid is 5-6 mol / L; Preferably, the second water-retaining agent is hydrophilic vapor-phase SiO2; Preferably, the surfactant is selected from one or more of hydrocarbon chain surfactants and fluorinated surfactants; the hydrocarbon chain surfactant is selected from one or more of anionic hydrocarbon chain surfactants and nonionic hydrocarbon chain surfactants; the anionic hydrocarbon chain surfactant is selected from one or more of alkyl sulfates, alkylbenzene sulfonates and alkyl carboxylates; the nonionic hydrocarbon chain surfactant is selected from one or more of polyoxyethylene alkyl ethers and polyoxyethylene alkyl aryl ethers; and the fluorinated surfactant is selected from one or more of perfluoroalkyl sulfonates.

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