Electrochemical NO sensor and preparation method of working electrode of electrochemical NO sensor
By modifying the electron mediator material on the working electrode surface of the electrochemical NO sensor, NO catalysis is achieved using the proton coupled electron transfer mechanism, and returning to the initial state under the applied voltage, the problem of short cycle life of the electrode modification material in the prior art is solved, and the working electrode life and number of cycles of the sensor are improved.
Patent Information
- Application Number
- CN202411715514.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-27
- Publication Date
- 2025-03-04
AI Technical Summary
The working electrode modification materials of existing electrochemical NO sensors have short cycle life, resulting in short sensor life.
The working electrode is modified by using the electronic mediator material, the proton-coupled electron transfer mechanism is used to realize the catalysis of NO, and the electronic mediator material returns to the initial state under the applied voltage to avoid loss.
It improves the working electrode life of the NO sensor, extends the number of cycles of the sensor, and enhances the reliability of detection.
Smart Images
Figure CN119555785A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of electrochemical sensors, and in particular to an electrochemical NO sensor and a method for preparing a working electrode of the electrochemical NO sensor. Background Art
[0002] Nitric oxide (NO) participates in and regulates many physiological processes in the human body. Respiratory NO is produced by inflammatory cells, nasal and tracheal epithelial cells, and is currently the most widely used molecular marker for airway inflammation. Oral exhaled NO can be used to diagnose inflammation and evaluate the efficacy of treatment. The oral exhaled NO concentration of a normal adult is 25-50 ppb, so there are relatively high requirements for the detection limit of NO. In addition, nasal exhaled NO gas mainly reflects the production of NO gas by the sinuses and nasal mucosa, which is related to diseases such as allergic rhinitis. Patients with rhinitis may exceed 1000 ppb, so there are requirements for the upper limit of NO detection.
[0003] The detection methods of NO include electron spin resonance spectroscopy, chemiluminescence, fluorescence spectrophotometry and electrochemical methods. Among them, electrochemical detection technology has the advantages of high sensitivity, fast response speed and low price, and can achieve ppb-level response to NO. However, NO has a large overpotential at conventional electrodes, and its oxidation peak potential is often relatively positive, which is not conducive to electrochemical detection. Therefore, modified electrodes are currently used to achieve electrocatalytic oxidation of NO. Common modification materials include carbon nanomaterials, metal and metal oxide nanoparticles, organic molecular polymers and metal porphyrin polymers. However, it should be noted that when performing NO detection, the modified material forms a closed loop by transferring the electrons of the reactant, that is, NO reacts directly on the surface of the traditional modified material, which causes the electrode modification material to be consumed, and the corresponding cycle life is small, resulting in a shorter working electrode life of the NO sensor.
[0004] Therefore, how to solve the problem of short working electrode life of NO sensor caused by the short cycle life of electrode modification materials is a technical problem that has yet to be solved. Summary of the invention
[0005] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes an electrochemical NO sensor and a method for preparing a working electrode of the electrochemical NO sensor, by modifying the surface of the working electrode of the electrochemical NO sensor with an electron mediator material, utilizing the proton-coupled electron transfer mechanism of the electron mediator to achieve NO catalysis, and utilizing the mechanism that the electron mediator can return to the initial state under an applied voltage and re-participate in the reaction, which can achieve NO catalysis on the one hand and avoid the loss of electrode modification materials on the other hand, thereby improving the working electrode life of the NO sensor.
[0006] According to the electrochemical NOx sensor of the first aspect of the present application, the electrochemical NOx sensor comprises:
[0007] Working electrode, reference electrode, counter electrode and electrolyte;
[0008] Wherein, the surface of the working electrode is modified with an electron mediator material, and the electron mediator material includes a quinoxaline ring organic substance.
[0009] In some possible implementations, the working electrode is a graphite electrode, the reference electrode and the counter electrode are both carbon platinum electrodes, and the electrolyte is a sulfuric acid electrolyte.
[0010] In some possible implementations, a Nafion membrane is also attached to the surface of the working electrode, and the Nafion membrane covers the surface of the electron mediator material.
[0011] In some possible implementations, the electrochemical NO sensor further includes:
[0012] Shell, fiberglass and three pins;
[0013] The working electrode, the reference electrode and the counter electrode are coaxially arranged in sequence and disposed in the outer shell, the glass fiber is used to absorb the electrolyte and separate the working electrode, the reference electrode and the counter electrode, and the three pins are disposed outside the outer shell and are respectively connected to the working electrode, the reference electrode and the counter electrode.
[0014] According to the second aspect of the present application, a method for preparing a working electrode of an electrochemical NO sensor comprises:
[0015] Constructing a three-electrode system, wherein the electrolyte of the three-electrode system contains an electron mediator material, and the working electrode of the three-electrode system is a target electrode;
[0016] Using cyclic voltammetry on the three-electrode system to deposit the electron mediator material on the surface of the target electrode;
[0017] A Nafion solution is dripped onto the surface of the target electrode and dried to obtain a working electrode of the electrochemical NO sensor.
[0018] In some possible implementations, the preparation method further includes:
[0019] The graphite slurry is scraped onto a polytetrafluoroethylene (PTFE) film and dried to obtain the target electrode.
[0020] In some possible implementations, before the step of dripping a Nafion solution on the surface of the working electrode of the three-electrode system and drying it to obtain the working electrode of the electrochemical NO sensor, the preparation method further includes:
[0021] The target electrode on which the electron mediator material is deposited is rinsed with deionized water and dried.
[0022] In some possible implementations, the electron mediator material is a quinoxaline ring organic compound.
[0023] In some possible implementations, the quinoxaline ring organic matter includes one or more of quinoxaline, quinoline, carbadox and mequindox, and the total concentration of the quinoxaline ring organic matter is 0.1 to 10 mmol / L.
[0024] In some possible implementations, the reference electrode and the counter electrode of the three-electrode system are respectively a saturated calomel electrode and a platinum wire electrode, and the electrolyte of the three-electrode system is a phosphate buffer solution containing the quinoxaline ring organic compound.
[0025] The electrochemical NO sensor and the method for preparing the working electrode of the electrochemical NO sensor according to the embodiments of the present application have at least the following beneficial effects:
[0026] The working electrode of the electrochemical NO sensor of the present application is modified with an electron mediator material. When a constant voltage is applied, the electron mediator material as an electrode modification material can be used repeatedly. Due to the existence of this mechanism of the electron mediator material, during the use of the electrochemical NO sensor, the electron mediator material as an electrode modification material can avoid loss as much as possible, thereby increasing the number of cycles of the sensor.
[0027] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:
[0029] Figure 1 This is a schematic diagram of the structure of an electrochemical NO sensor shown in an embodiment of the present application;
[0030] Figure 2 This is a schematic diagram of the shapes of the electrodes of the electrochemical NO sensor shown in the embodiment of the present application;
[0031] Figure 3 This is a schematic flow chart of a method for preparing a working electrode of an electrochemical NO sensor according to an embodiment of the present application. DETAILED DESCRIPTION
[0032] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.
[0033] In the description of this application, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.
[0034] In the description of the present application, it should be understood that descriptions involving orientation, such as up, down, left, right, front, back, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.
[0035] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.
[0036] In the description of this application, it should be noted that, unless otherwise clearly defined, the terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this application in combination with the specific content of the technical solution. In addition, the identification of specific steps below does not represent a limitation on the order of steps and execution logic. The execution order and execution logic between each step should be understood and inferred with reference to the contents described in the embodiment.
[0037] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes an electrochemical NO sensor and a method for preparing a working electrode of the electrochemical NO sensor.
[0038] Some concepts involved in this application are explained below.
[0039] Modified electrode: A chemically modified electrode is an electrode made of a conductor or semiconductor. The electrode surface is modified by chemical or physical methods according to people's design intentions to form a thin film with the expected functions, such as accelerated electron transfer reaction, selective membrane permeability, preferential enrichment, higher selectivity, sensitivity and stability.
[0040] Electron mediator: Electron mediator, also known as electrocatalyst, is fixed on the electrode and can promote or inhibit the electron transfer reaction occurring on the electrode under the action of the electric field. This promotion effect does not depend on the chemical change of the modifier itself, but changes the potential or reaction rate of the reaction on a large scale by changing the state of the electrode surface or the modifier in the solution. This effect enables the electrode to not only have the function of electron transfer, but also to promote and select the electrochemical reaction. The reaction process includes two or more consecutive steps, and chemically adsorbed intermediates are generated on the electrode surface (directly participating in the reaction of the reactants), thereby effectively accelerating or slowing down the rate of electron transfer and improving the reaction efficiency and selectivity of the electrode. And under the condition of applied voltage, it will return to the starting state and re-participate in the reaction.
[0041] Proton-coupled electron transfer (PCET) is a process involving the transfer of both electrons and protons in a chemical reaction. This transfer usually occurs within or between molecules and is a key step in many important biochemical reactions and energy conversion processes.
[0042] Cyclic Voltammetry (CV) is an electrochemical analysis technique mainly used to study the redox behavior of substances in solution. This technique measures the current response of a substance under potential changes by applying forward and reverse scanning voltages to the electrode, thereby obtaining electrochemical information of the substance, such as the position, morphology and peak potential of the redox peak. Cyclic voltammetry is widely used in analytical chemistry, electrochemistry, materials science, chemical analysis, biomedicine and other fields. The application of cyclic voltammetry in this application belongs to a kind of electrochemical deposition technology, and its basic principle is: in the experiment, the potential on the electrode starts to scan from a more negative value, gradually increases to a more positive potential, and then returns to a more negative potential, and finally returns to the initial potential. In this process, continuous redox reactions will occur on the electrode, generating corresponding current signals. By measuring and analyzing these current signals, the electrochemical behavior characteristics of the substance to be measured can be obtained.
[0043] The specific embodiments of the present application are further described below based on the accompanying drawings.
[0044] Please refer to the attached Figure 1 , attached Figure 1 This is a schematic diagram of the structure of an electrochemical NO sensor provided in an embodiment of the present application. The electrochemical NO sensor may include:
[0045] A working electrode, a reference electrode, a counter electrode and an electrolyte. The surface of the working electrode is modified with an electron mediator material, and the electron mediator material includes a quinoxaline ring organic substance.
[0046] like Figure 1 As shown, in this embodiment, the electrochemical NO sensor is a three-electrode system electrochemical gas sensor. Among them, the working electrode, the reference electrode and the counter electrode are all arranged in the sensor housing, the glass fiber is used to separate the three electrodes and adsorb the electrolyte to form a closed loop, and three pins are arranged at the bottom of the housing, which are respectively connected to the three electrodes.
[0047] During the use of the sensor, a specific constant voltage needs to be applied to the working electrode to make it run until the baseline is stable, and then the gas to be tested is introduced for detection. During the detection, the electron mediator material on the working electrode has the characteristics of proton-coupled electron transfer (PCET), and its reaction mechanism is as follows:
[0048] Reaction 1: NO+PCET-O→NO3-+PCET-R
[0049] Reaction 2:
[0050] Among them, in reaction 1, NO loses electrons and oxidizes to NO3-, and the oxidized state (POCT-O) of the electron mediator material gains electrons and becomes reduced state (POCT-R). In reaction 2, the reduced state (POCT-R) of the electron mediator material becomes oxidized state (POCT-O) under a specific constant voltage, so that it can re-enter reaction 1, that is, under the condition of applying a constant voltage, the electron mediator material as an electrode modification material can be recycled and reused. Due to the existence of this mechanism of the electron mediator material, the electron mediator as an electrode modification material can avoid loss as much as possible during the use of the electrochemical NO sensor, thereby increasing the number of cycles of the sensor.
[0051] In addition, different electron mediator materials require different constant voltage values. In a specific implementation, the electron mediator material may include a quinoxaline ring organic compound, and in this case, the constant voltage value is specifically 0.35V.
[0052] The electrochemical NO sensor according to the embodiment of the present application has at least the following beneficial effects:
[0053] The working electrode of the electrochemical NO sensor of the present application is modified with an electron mediator material, and under the condition of applying a constant voltage, the electron mediator material as an electrode modification material can be used repeatedly. Therefore, during the use of the electrochemical NO sensor, the electron mediator as an electrode modification material can avoid loss as much as possible, thereby increasing the number of cycles of the sensor.
[0054] In some possible implementations, the working electrode is a graphite electrode, the reference electrode and the counter electrode are both carbon platinum electrodes, and the electrolyte is a sulfuric acid electrolyte.
[0055] In this embodiment, the electrode material of the electrochemical NO sensor includes a substrate and a catalyst layer. The graphite electrode and the carbon platinum electrode here refer to the catalyst layer of the electrode using graphite slurry and platinum carbon slurry materials respectively. The substrate of the electrode can be a PTFE film. The specific graphite slurry content of the working electrode can be 70-90%wt, and the rest is a binder. Since the working electrode uses a graphite electrode, and graphite has the advantages of low price, large specific surface area and good conductivity, it can be used as a catalyst carrier, and organic matter with quinoxaline rings can be electrodeposited on the graphite surface, thereby improving the sensitivity of the working electrode and at the same time improving the life of the working electrode.
[0056] In addition, in a specific implementation, the above-mentioned PTFE film can be set as a disc with a diameter of 25 mm; the platinum carbon slurry is scraped into a circular shape with a diameter of 14 to 20 mm; the diameter of the reference electrode is 8 to 12 mm; the drying temperature is 40 to 100°C, and the time is 1 to 6 hours.
[0057] In some possible implementations, a Nafion membrane is further attached to the surface of the working electrode, and the Nafion membrane covers the surface of the electron mediator material.
[0058] In this embodiment, a Nafion membrane is attached to the surface of the working electrode, and the Nafion membrane also covers the surface of the electron mediator material, which can prevent the electron mediator material from falling off, thereby ensuring a longer cycle life of the sensor.
[0059] In some possible implementations, specific reference is made to Figure 1 In the above-mentioned figures, the electrochemical NO sensor may further include:
[0060] Shell, fiberglass and three pins;
[0061] The working electrode, the reference electrode and the pair of electrodes are coaxially arranged in sequence and disposed in the shell. The glass fiber is used to absorb the electrolyte and separate the working electrode, the reference electrode and the pair of electrodes. The three pins are disposed outside the shell and are respectively connected to the working electrode, the reference electrode and the pair of electrodes.
[0062] In some possible implementations, specific reference is made to Figure 2 In the drawings, the shapes of the reference electrode and the counter electrode are circular and ring-shaped respectively, and the diameter of the reference electrode is the same as the diameter of the inner ring of the counter electrode.
[0063] In this embodiment, the reference electrode and the counter electrode are made of the same electrode material, such as a carbon platinum electrode, and the reference electrode and the counter electrode are circular and annular in shape, respectively, and the diameter of the reference electrode is the same as the diameter of the inner ring of the counter electrode. Therefore, when preparing the reference electrode and the counter electrode, the two electrodes can be produced by a cutting method, that is, a circular electrode of the size of the outer ring of the counter electrode is first produced, and then the center circle is cut out according to the size of the reference electrode as the reference electrode, and the remaining annular part is used as the counter electrode, which simplifies the production process of the reference electrode and the counter electrode.
[0064] The present application also provides a method for preparing a working electrode of an electrochemical NO sensor, which specifically includes:
[0065] Step S301: constructing a three-electrode system, wherein the electrolyte of the three-electrode system contains an electron mediator material, and the working electrode of the three-electrode system is a target electrode;
[0066] Step S302: using cyclic voltammetry on the three-electrode system to deposit the electron mediator material on the surface of the target electrode;
[0067] Step S303: dripping Nafion solution onto the surface of the target electrode and drying the solution to obtain a working electrode of the electrochemical NO sensor.
[0068] In this embodiment, the three-electrode system includes a working electrode, a reference electrode, a counter electrode and an electrolyte, and the working electrode of the three-electrode system is a target electrode. Referring to the above introduction to cyclic voltammetry, cyclic voltammetry is used in combination with the three-electrode system to deposit an electron mediator material on the surface of the target electrode to form an electrode modification material, and after the deposition is completed, a Nafion solution is dripped on the surface of the target electrode and dried to obtain a working electrode of an electrochemical NO sensor.
[0069] The potential range of the cyclic voltammetry method can be -0.6 to 1.2 V, the scanning speed can be 0.01 to 0.2 V / s, and the number of cycles can be 10 to 50. The concentration of the Nafion solution is 0.1% to 1% wt, the volume is 40 to 200 μL, the drying temperature is 40 to 100° C., and the time is 1 to 6 hours.
[0070] The method for preparing the working electrode of the electrochemical NO sensor according to the embodiment of the present application has at least the following steps:
[0071] Beneficial effects:
[0072] Combined with the above description of the reaction mechanism of the electron mediator, the electron mediator material as an electrode modification material can be recycled and reused under the condition of applying a constant voltage. Due to the existence of this mechanism of the electron mediator material, the electron mediator as an electrode modification material can avoid loss as much as possible during the use of the electrochemical NO sensor, thereby increasing the number of cycles of the sensor. In addition, after the electron mediator material is deposited on the surface of the target electrode, a Nafion solution is dripped on the surface of the target electrode and dried, and after drying, the Nafion solution can form a stable film on the surface of the electrode modification material, thereby avoiding the electron mediator material from falling off, ensuring a longer cycle life of the sensor.
[0073] In some possible implementations, before step S301, the preparation method may further include:
[0074] The graphite slurry was coated on the PTFE film and dried to obtain the target electrode.
[0075] In this embodiment, the target electrode may specifically be a graphite electrode, that is, the catalyst layer is made of graphite slurry.
[0076] In a specific implementation, the graphite slurry content of the above-mentioned graphite electrode can be 70-90%wt, and the rest is adhesive; the PTFE film is a disc with a diameter of 25mm, and the graphite slurry coating shape is a circle with a diameter of 6-20mm; the drying temperature range is 40-100°C; the drying time range is 1-6h.
[0077] Since the target electrode's catalyst layer uses graphite slurry, the graphite can be oxidized by cyclic voltammetry, and the generated oxidized groups such as carboxyl groups can promote the oxidation of NO. That is, after the target electrode uses a graphite electrode, after the electron mediator material is deposited by the above-mentioned cyclic voltammetry, a composite electrode modification material in which the electron mediator and graphite oxidized groups coexist can be generated on the catalyst layer surface of the target electrode, thereby improving the sensitivity and life of the electrochemical NO sensor.
[0078] In some possible implementations, before step S303: adding a Nafion solution to the surface of the working electrode of the three-electrode system and drying the solution to obtain the working electrode of the electrochemical NO sensor, the preparation method further includes:
[0079] The target electrode on which the electron mediator material is deposited is rinsed with deionized water and dried.
[0080] In this embodiment, after the electron mediator material is deposited on the surface of the target electrode, the target electrode may be rinsed with deionized water and dried to remove surface impurities on the target electrode, such as electrolyte residues.
[0081] In a specific implementation, the drying process after the deionized water rinsing can be set to: a drying temperature of 40 to 100° C. and a drying time of 1 to 6 hours.
[0082] In some possible implementations, the electron mediator material is a quinoxaline ring organic compound.
[0083] In this embodiment, the electron mediator material may include quinoxaline ring organic matter. When the electrochemical NO sensor is used in practice, the constant voltage value applied to the working electrode is specifically 0.35V.
[0084] In some possible implementations, the quinoxaline ring organic matter includes one or more of quinoxaline, quinoline, carbadox and mequindox, and the total concentration of the quinoxaline ring organic matter is 0.1 to 10 mmol / L.
[0085] In some possible implementations, the reference electrode and the counter electrode of the three-electrode system are respectively a saturated calomel electrode and a platinum wire electrode, and the electrolyte of the three-electrode system is a phosphate buffer solution containing the quinoxaline ring organic compound.
[0086] The above is a specific description of the preferred implementation of the present application, but the present application is not limited to the above implementation mode. Technical personnel familiar with the field can also make various equivalent modifications or substitutions under the shared conditions without violating the spirit of the present application. These equivalent modifications or substitutions are all included in the scope defined by the claims of the present application.
Claims
1. An electrochemical NO sensor, characterized in that: include: Working electrode, reference electrode, counter electrode and electrolyte; Wherein, the surface of the working electrode is modified with an electron mediator material, and the electron mediator material includes a quinoxaline ring organic substance.
2. The electrochemical NO sensor according to claim 1, characterized in that The working electrode is a graphite electrode, the reference electrode and the counter electrode are both carbon platinum electrodes, and the electrolyte is a sulfuric acid electrolyte.
3. The electrochemical NO sensor according to claim 2, characterized in that: A Nafion membrane is also attached to the surface of the working electrode, and the Nafion membrane covers the surface of the electron mediator material.
4. The electrochemical NO sensor according to any one of claims 1 to 3, characterized in that: The electrochemical NO sensor further comprises: Shell, fiberglass and three pins; The working electrode, the reference electrode and the counter electrode are coaxially arranged in sequence and disposed in the outer shell, the glass fiber is used to absorb the electrolyte and separate the working electrode, the reference electrode and the counter electrode, and the three pins are disposed outside the outer shell and are respectively connected to the working electrode, the reference electrode and the counter electrode.
5. A method for preparing a working electrode of an electrochemical NO sensor, characterized in that: include: Constructing a three-electrode system, wherein the electrolyte of the three-electrode system contains an electron mediator material, and the working electrode of the three-electrode system is a target electrode; Using cyclic voltammetry on the three-electrode system to deposit the electron mediator material on the surface of the target electrode; A Nafion solution is dripped onto the surface of the target electrode and dried to obtain a working electrode of the electrochemical NO sensor.
6. The preparation method according to claim 5, characterized in that: The preparation method further comprises: The graphite slurry is scraped onto a polytetrafluoroethylene (PTFE) film and dried to obtain the target electrode.
7. The preparation method according to claim 5, characterized in that: Before the step of dripping a Nafion solution onto the surface of the working electrode of the three-electrode system and drying the solution to obtain the working electrode of the electrochemical NO sensor, the preparation method further comprises: The target electrode on which the electron mediator material is deposited is rinsed with deionized water and dried.
8. The preparation method according to any one of claims 5 to 7, characterized in that: The electron mediator material is a quinoxaline ring organic compound.
9. The preparation method according to claim 8, characterized in that: The quinoxaline ring organic matter includes one or more of olaquindox, quinoline, carbadox and mequindox, and the total concentration of the quinoxaline ring organic matter is 0.1-10 mmol / L.
10. The preparation method according to claim 8, characterized in that: The reference electrode and the counter electrode of the three-electrode system are saturated calomel electrode and platinum wire electrode respectively, and the electrolyte of the three-electrode system is a phosphate buffer solution containing the quinoxaline ring organic compound.