Copper-catalyzed carbon dioxide microsensor and method of making same

Abstract

The application provides a copper catalysis based carbon dioxide micro-sensor and a preparation method thereof, and comprises an electrode shell, a first gas permeable membrane arranged at one end of the electrode shell, a working electrode, a reference electrode and a protection electrode arranged in the electrode shell and immersed in an electrolyte, two closed loop polarization circuits formed by the reference electrode and the working electrode and the reference electrode and the protection electrode under a polarization voltage, and the three electrodes all pointing to the first gas permeable membrane.The carbon dioxide micro-sensor has higher sensitivity, reaches a detection limit of micromole per liter, has a micron level diameter size of a sensor probe, can be used for nondestructive in-situ monitoring of samples such as sediments or soil, has strong anti-interference ability, avoids the generation of interference signals such as hydrogen evolution and nitrous oxide under a lower polarization voltage, and can be applied to complex environments.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrochemical micro-sensor for environmental monitoring, and particularly relates to a carbon dioxide micro-sensor based on copper catalysis and a preparation method thereof. BACKGROUND

[0002] In the face of the increasingly serious global climate change problem, the core problem is to reduce the emission of carbon dioxide greenhouse gas without significant interference to the economy. Therefore, according to different monitoring targets, the technical means for monitoring carbon dioxide in the environment should be diversified.

[0003] At present, carbon dioxide monitoring in the market relies on two technical means. One is a carbon dioxide sensor device developed by using the infrared absorption characteristic spectrum of carbon dioxide. This kind of sensor is widely used in industrial and agricultural production environments, but due to the fact that the gas inlet and the detection electronic module are concentrated in one system, its size is large (several centimeters to tens of centimeters), and it is still difficult to be applied to the detection of carbon dioxide concentration in a micron or sub-centimeter micro-environment gradient. The second kind of sensor is an electrochemical carbon dioxide sensor invented by the European Unisense company. The structure of this sensor is basically similar to that of the present application, but its shortcomings are short service life (about three months), non-selective catalysis, and high polarization voltage (-720 mV), which makes the sensor relatively sensitive to hydrogen protons in the solvent environment and causes interference of hydrogen evolution signal. SUMMARY

[0004] To solve the above technical problems, the present application provides a carbon dioxide micro-sensor based on copper catalysis and a preparation method thereof, which improves the micro-sensor technology for monitoring carbon dioxide in the environment and soil and biological systems, and is a new member in the field of micro-sensors. The carbon dioxide gas in the environment diffuses into the salt-containing protective sleeve through the gas-permeable membrane, removes the interfering gas, and then further penetrates into the surface of the working electrode immersed in the electrolyte through the two-layer gas-permeable membrane. Under the driving of the polarization voltage, the gas is selectively catalytically reduced, and a polarization micro-current is generated between the working electrode and the pseudo-reference electrode, which is proportional to the concentration of the detected gas.

[0005] To achieve the above purpose, the present application provides a carbon dioxide micro-sensor based on copper catalysis and a preparation method thereof. The carbon dioxide micro-sensor based on copper catalysis comprises an electrode shell,

[0006] One end of the electrode shell is provided with a first gas-permeable membrane;

[0007] The electrode shell is internally provided with a working electrode, a reference electrode and a protective electrode; the working electrode, the reference electrode and the protective electrode are all located in an electrode inner chamber and are immersed in an electrolyte; under a polarization voltage, the reference electrode and the working electrode and the reference electrode and the protective electrode form two closed loop polarization circuits respectively; all of them are directed to the first gas-permeable membrane; wherein the working electrode is located at a first preset distance above the first gas-permeable membrane and is used for polarizing carbon dioxide gas diffused to the surface of the electrode through the first gas-permeable membrane; the protective electrode is located at a second preset distance above the first gas-permeable membrane and is used for reducing the signal interference of intermediate reaction products; the reference electrode is located at the uppermost part of the chamber and at the other end of the working electrode and is used for forming a loop.

[0008] Optionally, the front end of the electrode shell is provided with an electrode protective sleeve filled with an acidic chromous chloride solution for removing oxygen interference; the electrode protective sleeve is located below the first gas-permeable membrane and is circumferentially glued to the upper part of the electrode shell to form a relatively closed electrode structure filled with deoxidizing solution inside.

[0009] Optionally, the tip outlet of the electrode protective sleeve is provided with a second gas-permeable membrane, and the electrode protective sleeve contains an acidic chromous chloride solution.

[0010] Optionally, the electrode shell further contains an electrolyte, the electrolyte is a single ionic liquid, and the electrolyte is used for inhibiting hydrogen protons in the environmental background.

[0011] Optionally, the electrode shell is made of drawn glass, one end of which is a tip structure, the other end is connected with a lead wire and is glued to form an electrode inner chamber which is isolated from the outside and can be pre-filled with electrolyte; the tip diameter of the electrode shell is micron level, and the first gas-permeable membrane is arranged at the tip outlet of the electrode shell.

[0012] Optionally, the working electrode comprises: a hollow glass filament, a platinum wire comprising a tip and a tail end is inserted into the hollow glass filament, the tip and the tail end of the platinum wire are exposed outside the hollow glass filament and are connected with a lead wire to transmit an electric current polarization signal outward.

[0013] Optionally, the tip of the platinum wire is covered with a copper atom layer.

[0014] On the other hand, the application also provides a preparation method of a carbon dioxide microsensor based on copper catalysis, comprising:

[0015] The working electrode and the protective electrode are respectively prepared based on glass packaging of a platinum wire;

[0016] The reference electrode is prepared based on a bare silver wire;

[0017] The electrode shell with a tip of nanometer level is prepared based on a glass tube, and silica gel is filled in the tip outlet of the electrode shell to form a first gas-permeable membrane;

[0018] The working electrode, the protection electrode and the reference electrode are assembled in the electrode shell, and the ionic liquid electrolyte is filled in the electrode shell;

[0019] The electromagnetic insulation cable is connected to the working electrode, the protection electrode and the reference electrode respectively, and the three electrodes are connected to the external circuit through the signal shielding line to apply the polarization potential and collect the current signal; the tail end of the electrode shell is glued and fixed to form a relatively sealed electrode connection system;

[0020] The electrode protection sleeve with a tip of micrometer diameter is prepared based on a glass tube, and silica gel is filled in the tip of the electrode protection sleeve to form a second gas-permeable membrane; and the preparation of the carbon dioxide micro-sensor is completed.

[0021] Optionally, the preparation of the working electrode comprises:

[0022] The glass is drawn into a glass filament tube;

[0023] One end of the platinum wire is ablated into a platinum wire tip with a diameter of micrometer level;

[0024] The platinum wire is inserted into the glass filament tube, and the platinum wire tip and tail end are exposed and sealed in the middle;

[0025] The platinum wire tip is covered with an atomic level thick catalytic copper atom layer.

[0026] Optionally, the assembling of the working electrode, the protection electrode and the reference electrode in the electrode shell comprises:

[0027] The working electrode is assembled into the electrode shell, and the tip of the working electrode is close to the first gas-permeable membrane;

[0028] The protection electrode is assembled to the first gas-permeable membrane of the electrode shell;

[0029] The reference electrode is assembled.

[0030] Compared with the prior art, the present application has the following advantages and technical effects:

[0031] ①The sensitivity is higher, and the detection limit reaches the micromolar per liter level, which fully meets the carbon dioxide monitoring in natural environment and biological body;

[0032] ②The diameter size of the sensor probe is micrometer level (between 10 micrometers and 100 micrometers), which can be used for non-destructive in-situ monitoring of sediments or soil samples, and is very suitable for long-term monitoring of carbon dioxide in the occasion;

[0033] ③The sensor has strong anti-interference ability. The interference of hydrogen, hydrogen sulfide, acetic acid, ethanol and nitrous oxide commonly found in the environment can be ignored (less than 1.0% of the signal of carbon dioxide with the same concentration);

[0034] ④The sensor's low polarization voltage avoids the occurrence of hydrogen evolution interference signals and is suitable for complex environments such as seawater, sediment, fresh water, soil, and atmosphere;

[0035] ⑤The sensor life is longer than similar products, with a continuous working life of more than 6 months. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings:

[0037] Figure 1 Schematic diagram of the structure of a copper-catalyzed carbon dioxide microsensor according to an embodiment of the present invention;

[0038] Figure 2 Schematic diagram of a standard curve of a microsensor according to an embodiment of the present invention;

[0039] Figure 3 Schematic diagram of a microsensor detection tip according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0041] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0042] like Figure 1 、 Figure 3 As shown, this embodiment provides a carbon dioxide microsensor based on copper catalysis, comprising: an electrode housing;

[0043] A first breathable membrane is provided at one end of the electrode shell;

[0044] The electrode shell is internally provided with a working electrode, a reference electrode and a protective electrode; the working electrode, the reference electrode and the protective electrode are located in the electrode inner chamber and are immersed in the electrolyte; under the polarization voltage, the reference electrode and the working electrode, and the reference electrode and the protective electrode form two closed loop polarization circuits respectively; all of them point to the first gas permeable membrane; wherein the working electrode is located at a first preset distance above the first gas permeable membrane, and is used for polarizing the carbon dioxide gas diffused to the surface of the electrode through the first gas permeable membrane; the protective electrode is located at a second preset distance above the first gas permeable membrane, and is used for reducing the signal interference of the intermediate reaction product; the reference electrode is located at the uppermost of the chamber and at the other end of the working electrode, and is used for forming a loop.

[0045] The electrode shell is internally provided with a working electrode, a reference electrode and a protective electrode; the working electrode, the reference electrode and the protective electrode are located in the electrode inner chamber and are immersed in the electrolyte; under the polarization voltage, the reference electrode and the working electrode, and the reference electrode and the protective electrode form two closed loop polarization circuits respectively; all of them point to the first gas permeable membrane; wherein the working electrode is located at a first preset distance above the first gas permeable membrane, and is used for polarizing the carbon dioxide gas diffused to the surface of the electrode through the first gas permeable membrane; the protective electrode is located at a second preset distance above the first gas permeable membrane, and is used for reducing the signal interference of the intermediate reaction product; the reference electrode is located at the uppermost of the chamber and at the other end of the working electrode, and is used for forming a loop.

[0046] The front end of the electrode shell is provided with an electrode protective sleeve filled with acidic chromous chloride solution for removing oxygen interference; the electrode protective sleeve is located below the first gas permeable membrane (upper gas permeable membrane, such as Figure 1 ) and is circumferentially glued to the upper part of the electrode shell to form a relatively closed internal space filled with oxygen-removing chemicals.

[0047] Further, the tip outlet of the electrode protective sleeve is provided with a second gas permeable membrane, and the electrode protective sleeve contains acidic chromous chloride solution.

[0048] Further, the electrode shell further contains an electrolyte, and the electrolyte is a single ion liquid, and the electrolyte is used to suppress hydrogen protons in the environment background.

[0049] Further, the electrode shell is made of drawn glass, one end of which is a sharp end structure, the other end is connected with a lead wire, and is glued to form an electrode inner chamber which is isolated from the outside and can be pre-filled with electrolyte; the diameter of the tip of the electrode shell is micron level, and the first gas permeable membrane is arranged at the tip outlet of the electrode shell.

[0050] Further, the working electrode comprises: a hollow glass filament, a platinum wire comprising a tip and a tail end is inserted into the hollow glass filament, and the tip and the tail end of the platinum wire are exposed outside the hollow glass filament.

[0051] Further, the tip of the platinum wire is covered with a copper atom layer.

[0052] AsFigure 1 As shown, the embodiment provides a micro-sensing device for monitoring carbon dioxide, comprising:

[0053] Gaseous film diffusion module (E5): for isolating liquid and solid, only allowing gas to pass through, divided into a first gas diffusion film (upper layer, i.e., a first gas-permeable film) and a second gas diffusion film (lower layer, i.e., a second gas-permeable film);

[0054] Interfering substance removal module (E4): i.e., an electrode protection sleeve internal system, for removing oxygen gas interference and retaining carbon dioxide gas;

[0055] Carbon dioxide signal measurement module (E1): i.e., the working electrode of E1, which forms a loop with E2. At a planned voltage, a polarization current is generated, which is proportional to the concentration of carbon dioxide. This module is used to measure the concentration of the carbon dioxide gas;

[0056] Protective electrode module (E3): for consuming excess carbon dioxide gas in the device;

[0057] The overall working principle is that an external polarization voltage source is connected to the carbon dioxide signal measurement module and the protective electrode module to form two loops. The gas passes through the first gaseous film diffusion module, and the oxygen interfering substance is removed; then it continues to diffuse through the second gas diffusion film to the tip of the working electrode (E1) and is reduced. Details are as follows:

[0058] The gas-permeable film module E5 allows carbon dioxide gas to cross, but liquid and solid cannot penetrate the gas-permeable film.

[0059] The oxygen interfering substance removal module is located between the two layers of gas diffusion film E5 and is composed of an acidic salt filled in the protective sleeve.

[0060] The carbon dioxide signal acquisition module is composed of the reference electrode E2 and the working electrode E1 connected in series with a self-developed high-precision power supply and a high-precision ammeter. The power supply provides a polarization voltage, and the carbon dioxide on the surface of the working electrode generates a polarization current signal stronger than the background value, which is captured by the series ammeter; the signal is proportional to the concentration, and the determination curve as shown is obtained. Figure 2

[0061] The protective electrode module is composed of the reference electrode E2 and the protective electrode E1 connected in series with the same power supply as above, but only provides the same polarization voltage as the signal module at both ends, and does not acquire the polarization current signal, the purpose is only to consume excess carbon dioxide in the measurement system.

[0062] In the embodiment, a preparation method of a copper catalysis-based carbon dioxide micro-sensor is also provided, comprising:

[0063] The working electrode and the protective electrode are respectively prepared based on glass packaging of platinum wire.​

[0064] The reference electrode is prepared based on bare silver wire;

[0065] An electrode shell with a nanoscale tip is prepared based on a glass tube, the tip outlet of the electrode shell is filled with silica gel to form a first gas-permeable membrane;

[0066] The working electrode, the protection electrode and the reference electrode are assembled in the electrode shell, and the ion liquid electrolyte is filled;

[0067] The electromagnetic insulation cable is connected to the working electrode, the protection electrode and the reference electrode respectively, and the three electrodes are connected to the external circuit through the signal shielding line to apply the polarization potential and collect the current signal; the tail end of the electrode shell is glued and fixed to form a relatively sealed electrode connection system;

[0068] An electrode protection sleeve with a micrometer diameter tip is prepared based on a glass tube, silica gel is used to fill the tip of the electrode protection sleeve to form a second gas-permeable membrane; and the preparation of the carbon dioxide microsensor is completed.

[0069] Further, the working electrode is prepared by:

[0070] The glass is drawn into a glass filament tube;

[0071] One end of the platinum wire is ablated to form a platinum wire tip with a micrometer diameter;

[0072] The platinum wire is inserted into the glass filament tube, exposing the platinum wire tip and tail end, and the middle is heat sealed;

[0073] The platinum wire tip is covered with an atomic level thick catalytic copper atom layer.

[0074] The protection electrode and the working electrode use the same material and preparation process, but the length of the exposed tip is longer, about 500 microns.

[0075] Further, assembling the working electrode, the protection electrode and the reference electrode in the electrode shell includes:

[0076] The working electrode is assembled into the electrode shell, and the tip of the working electrode is close to the first gas-permeable membrane;

[0077] The protection electrode is assembled to the first gas-permeable membrane of the electrode shell;

[0078] The reference electrode is assembled.

[0079] In this embodiment, the preparation method specifically includes:

[0080] The working electrode and the protection electrode are prepared, wherein the working electrode includes a platinum wire tip and a tail end;

[0081] The electrode protection sleeve is prepared based on the platinum wire tip to remove interference and form an electrode protection shell;

[0082] The working electrode and the protection electrode are respectively assembled into the electrode protection shell and filled, the reference electrode is assembled and filled with electrolyte, the electrode connection system is sealed, and the assembly of the overall electrode is completed.

[0083] Preparation of working electrode (E1):

[0084] First step, select high-impedance high-stability glass with millimeter-level diameter, draw into hollow glass wire;

[0085] Second step, select high-purity platinum wire, one end of which is ablated into a platinum wire tip with micron-level diameter;

[0086] Third step, the platinum wire is inserted into the above-mentioned hollow glass wire, exposing the platinum wire tip and tail, and the middle is heat-sealed; standby;

[0087] Fourth step: sputtering copper atoms on the platinum wire tip to form a copper atom sputtering layer with a thickness of 10 μm or less.

[0088] Preparation of reference electrode (E2):

[0089] Select high-purity (99.99%) bare silver wire.

[0090] Preparation of protection electrode (E3):

[0091] The steps are the same as the working electrode preparation process.

[0092] Preparation of electrode protection sleeve (E4):

[0093] First step: draw a high-impedance glass tube into a shell with a micron-diameter tip;

[0094] Second step: fill the tip with silicone (polytetrafluoro) to form a second gas diffusion layer.

[0095] Overall electrode assembly Figure 1 ):

[0096] First step, draw a high-impedance glass tube into an electrode shell with a micron-level tip;

[0097] Second step, fill the electrode shell outlet with silicone;

[0098] Third step, assemble the working electrode into the shell, with the tip close to the silicone shell;

[0099] Fourth step, assemble the protection electrode to the silicone layer of the shell;

[0100] Fifth step, assemble the reference electrode (E2);

[0101] Sixth step, fill the electrolyte;

[0102] Step 7, the electromagnetic insulation cable is connected to the reference electrode, working electrode and protection electrode respectively;

[0103] Step 8, the electrode connection system is sealed by sealing glue;

[0104] Step 9, the electrode tip is added with a protective sleeve (E4) filled with a filtering solution.

[0105] In the micro-sensor device, a silica gel gas diffusion membrane is used for the interface in contact with the external environment. An ionic liquid mixed solution is used for the electrolyte to suppress the interference of hydrogen protons in the environmental background. Copper atoms are sputtered on the surface of the platinum wire of the working electrode to increase the sensitivity and selectivity of the electrode to carbon dioxide and further exclude the interference of methane, hydrogen and the like. A stretched glass tube sealing process is used, and the diameter of the electrode tip is kept at microns to minimize the damage of the sensor to the sample.

[0106] Outside the sensor tip, a glass tube containing an acidic salt solution is sleeved, and the tip of the protective sleeve uses a gas permeable membrane with the same process as the technical solution feature one to reduce the interference of other gases on the micro-sensor.

[0107] The micro-sensor proposed in the embodiment is based on the principle of electrochemical copper selective catalysis. It has significant differences in reaction mechanism and preparation method, and has lower polarization voltage, stronger anti-interference ability and lower detection limit, and the comprehensive performance is higher than the international level.

[0108] In the embodiment: the whole carbon dioxide micro-sensor adopts a drawn glass to form an outer shell sleeve, and the tip diameter is as low as microns. This structure can effectively reduce the damage to the sample such as sediment and realize in-situ measurement of the sample;

[0109] The working electrode is packaged with high impedance glass, the exposed length of the tip is micron level, and the tip is plated with micron level thickness copper. Under the polarization voltage applied between the reference electrode and the working electrode, carbon dioxide occurs at the tip of the working electrode, generating a detectable polarization current;

[0110] A stretched glass tube sealing process is used, and the diameter of the electrode tip is kept at micron level to minimize the damage of the sensor to the sample.

[0111] The sensor tip and the opening tip of the protective sleeve both use a gas-permeable polytetrafluoroethylene film. The film structure helps to increase the gas diffusion rate and improve the sensitivity.

[0112] The working electrode can use a metal sputtering process, and the surface is covered with atomic level thickness copper atoms to increase the sensitivity and selectivity of the electrode to carbon dioxide and further exclude the interference of other oxidizing gases, with lower working voltage and higher anti-interference performance;

[0113] The electrolyte solution uses a single ionic liquid instead of a water (or mixed ionic liquid) solution, reduces the carbon dioxide dissolution equilibrium time, and makes the electrode have an extremely short response time (120 ms) and a signal equilibrium time shortened to within one minute. In the embodiment, the electrolyte can use dimethylformamide ionic liquid to inhibit hydrogen protons in the environmental background.

[0114] The micro-sensing device for monitoring carbon dioxide and the preparation method of the embodiment have strong selectivity to carbon dioxide and are not sensitive to hydrogen, hydrogen sulfide, methane, carbon monoxide and other gases in the soil and sediment environment, and are not sensitive to pH value, salinity and stirring changes. The sensitivity of the micro-sensing device is 3-6 orders of magnitude higher than that of a conventional sensor, reaches 5 nanomoles per liter, and can be used to monitor carbon dioxide in the environmental background. The device of the embodiment can work continuously for more than six months, the diameter of the detection sensitive unit is micron level, and the soil and sediment samples to be measured are not damaged.

[0115] The embodiment redesigns the structure and composition of the sensor by using electrochemical principles to adapt to the environmental monitoring system. The diameter of the sensor probe tip is optimized to micron level. The "electrode-diffusion" reaction occurring in the capillary tube can easily generate a relatively strong polarization current, making the detection signal more sensitive.

[0116] The extremely gas-permeable polytetrafluoroethylene film is used to increase the diffusion amount of the detected gas, further improving the sensitivity.

[0117] The single-atom copper sputtering coating is used on the surface of the working electrode by using atomic layer deposition technology, and the huge specific surface is used to selectively catalyze and reduce carbon dioxide.

[0118] The electrode tip uses a sleeve process containing chromium ions, which has extremely strong anti-oxygen interference capacity (52.0 mg / L) and completely removes the interference of oxygen in the air.

[0119] The carbon dioxide electrochemical sensor based on copper catalysis proposed in the embodiment is a unique feature and is different from other carbon dioxide electrochemical sensors. The copper sputtering process, copper plating, and copper materials use similar methods to use copper catalysis technology to manufacture a carbon dioxide sensor, which should be included in the protection scope of the present application.

[0120] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements easily thought of by those skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A carbon dioxide microsensor based on copper catalysis, characterized in that: include: Electrode housing, A first breathable membrane is provided at one end of the electrode shell; A working electrode, a reference electrode and a protective electrode are arranged inside the electrode shell; The working electrode, reference electrode, and guard electrode are all located in the electrode chamber and immersed in the electrolyte. Under polarization voltage, the reference electrode and the working electrode, and the reference electrode and the guard electrode respectively form two closed-loop polarization circuits. All three electrodes point toward the first breathable membrane. The working electrode is located at a first preset distance above the first breathable membrane and is used to polarize carbon dioxide gas diffused through the first breathable membrane to the electrode surface. The guard electrode is located at a second preset distance above the first breathable membrane and is used to reduce signal interference from intermediate reaction products. The reference electrode is located at the other end of the working electrode and at the top of the chamber to form a loop. The working electrode comprises: a hollow glass filament, a platinum wire having a tip and a tail inserted into the hollow glass filament, the tip and the tail of the platinum wire being exposed outside the hollow glass filament and connected to a wire to transmit a current polarization signal outward; The tip of the platinum wire is covered with a layer of copper atoms; The front end of the electrode shell is provided with an electrode protective sleeve for removing oxygen interfering substances and filled with an acidic chromium chloride solution; the electrode protective sleeve is located below the first breathable membrane and is circumferentially bonded to the upper portion of the electrode shell to form a relatively closed electrode structure filled with a deoxygenating solution; A second breathable membrane is provided at the tip outlet of the electrode protection sleeve, and the electrode protection sleeve contains an acidic chromium chloride solution; The electrode shell also contains an electrolyte, which is a single ion liquid and is used to suppress hydrogen protons in the environmental background.

2. The copper-catalyzed carbon dioxide microsensor according to claim 1, characterized in that: The electrode shell is made of drawn glass, one end of which is a pointed structure and the other end is connected to a wire and glued to form the electrode inner chamber which is isolated from the outside world and hollow and can be pre-filled with electrolyte; the tip diameter of the electrode shell is at the micron level, and the first breathable membrane is provided at the tip outlet of the electrode shell.

3. The method for preparing a copper-catalyzed carbon dioxide microsensor according to any one of claims 1 to 2, wherein: include: Platinum wire was encapsulated on glass to prepare working electrode and guard electrode respectively; Based on bare silver wire, a reference electrode was prepared; An electrode shell with a nanometer-sized tip is prepared based on a glass tube, and the tip outlet of the electrode shell is sealed with silica gel to form a first breathable membrane; Assembling the working electrode, the guard electrode and the reference electrode in the electrode housing and filling the housing with an ionic liquid electrolyte; Electromagnetically insulated cables are connected to the working electrode, guard electrode, and reference electrode, respectively. The three electrodes are connected to an external circuit via a signal shielding cable to apply a polarization potential and collect current signals. The tail end of the electrode shell is glued and fixed to form a relatively sealed electrode connection system. An electrode protective cover with a micrometer-diameter tip is prepared based on a glass tube, and the tip of the electrode protective cover is filled with silicone to form a second breathable membrane; thus, the preparation of the carbon dioxide microsensor is completed.

4. The method for preparing a copper-catalyzed carbon dioxide microsensor according to claim 3, wherein: The preparation of the working electrode comprises: drawing the glass into a glass fiber tube; ablating one end of the platinum wire into a platinum wire tip with a diameter in the micrometer range; Inserting the platinum wire into the glass wire tube to expose the tip and tail of the platinum wire, and heating and sealing the middle; The tip of the platinum wire is covered with an atomically thick layer of catalytic copper atoms.

5. The method for preparing a copper-catalyzed carbon dioxide microsensor according to claim 3, wherein: Assembling the working electrode, the guard electrode and the reference electrode in the electrode housing comprises: Assembling the working electrode into the electrode housing, with the tip of the working electrode close to the first gas permeable membrane; Assembling the protective electrode to the first breathable membrane of the electrode housing; Assemble the reference electrode.

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