Electrochemical sensor for SiCl4 gas detection and preparation method thereof

Abstract

The invention provides an electrochemical sensor for SiCl4 gas detection and a preparation method thereof. The sensor comprises a solid electrolyte diaphragm, a working electrode, a reference electrode and a counter electrode, the working electrode comprises metal and a double-perovskite material, and the mass ratio of the metal to the double-perovskite material is 1: (1-5). The electrochemical sensor disclosed by the invention is excellent in high temperature resistance, can stably work at 1000-1500 DEG C, has the advantages of high detection precision, high response speed and good selectivity, and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of gas sensors, and in particular to an electrochemical sensor for SiCl4 gas detection and a preparation method thereof. Background Art

[0002] As an important chemical raw material and semiconductor process gas, SiCl4 is widely used in polysilicon production, chemical vapor deposition (CVD), and other fields. Accurately monitoring SiCl4 gas concentration in high-temperature process environments is crucial for controlling reaction progress, ensuring product quality, and preventing safety accidents. However, SiCl4 gas detection faces numerous challenges under extremely high temperature conditions (e.g., above 1000°C).

[0003] On the one hand, traditional gas sensor materials are prone to softening, volatilization, or chemical corrosion at high temperatures, leading to sensor failure. For example, common metal electrode materials melt rapidly under extremely high temperatures, unable to maintain stable electrical properties. Ordinary ceramic materials can also lose functionality due to high-temperature oxidation and thermal stress cracking. On the other hand, SiCl₄ gas is chemically active and can undergo complex reactions such as decomposition and hydrolysis at high temperatures, producing products such as Cl₂, HCl, and SiCl₂. Conventional detection methods have difficulty accurately distinguishing and quantifying the true concentration of SiCl₄.

[0004] While solid-state electrolyte electrochemical sensors currently offer advantages in high-temperature gas detection, effective technical solutions for the specific detection of SiCl₄ gas under extremely high temperatures remain lacking. Existing sensors suffer from low accuracy, slow response, and poor selectivity, making them unable to meet the real-time, precise detection requirements of SiCl₄ gas required in industrial production. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide an electrochemical sensor for SiCl4 gas detection and a preparation method thereof, so as to solve the problems of poor stability, poor selectivity, low detection accuracy and slow response speed of electrochemical sensors in the prior art under high temperature conditions.

[0006] To achieve the above objectives and other related objectives, the present invention provides an electrochemical sensor for SiCl4 gas detection and a preparation method thereof.

[0007] A first aspect of the present invention provides a working electrode for SiCl4 gas detection, wherein the working electrode comprises a metal and a double perovskite material, wherein the mass ratio of the metal to the double perovskite material is 1:(1-5).

[0008] Preferably, the mass ratio of the metal to the double perovskite material is 1:(1-4), including but not limited to 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5 or 1:4.

[0009] Preferably, the working electrode further comprises Al2O3, and the amount of Al2O3 is 0.5 to 2 times the total mass of the metal and the double perovskite material; for example, it can be 0.5 times, 0.8 times, 1.0 times, 1.2 times, 1.5 times, 1.8 times or 2.0 times.

[0010] Preferably, the metal is any one or two selected from Ta and Ti.

[0011] More preferably, the metal is Ta.

[0012] Preferably, the double perovskite material is Cs2NaBiCl6.

[0013] Preferably, the working electrode further includes a catalyst layer.

[0014] Preferably, the catalyst is Ir.

[0015] Preferably, the catalyst layer is fixed on the surface of the working electrode.

[0016] Further preferably, the catalyst layer is fixed on the surface of the working electrode by magnetron sputtering.

[0017] Preferably, the thickness of the catalyst layer is 50-100 nm.

[0018] Further preferably, the thickness of the catalyst layer is 70 to 90 nm, including but not limited to 70 nm, 72 nm, 75 nm, 78 nm, 80 nm, 82 nm, 85 nm, 88 nm or 90 nm.

[0019] A second aspect of the present invention provides an electrochemical sensor, comprising: a solid electrolyte membrane, the above-mentioned working electrode, reference electrode and counter electrode; the working electrode, reference electrode and counter electrode are fixed to the surface of the solid electrolyte membrane.

[0020] Preferably, the fixing includes adhering each electrode to the surface of the solid electrolyte membrane using an adhesive, and the adhering method includes any one or both of the following methods:

[0021] 1) doping the binder into the electrode raw material and coating the electrode on the surface of the solid electrolyte membrane;

[0022] 2) Applying a binder to the surface of the electrode and attaching the electrode to the surface of the solid electrolyte membrane.

[0023] In some preferred embodiments of the present invention, the working electrode and the counter electrode are coated onto the surface of the solid electrolyte membrane using the above-mentioned method 1).

[0024] More preferably, the raw materials of the working electrode also include a binder, and the amount of the binder is 0.1 to 2 times the total mass of the metal and the double perovskite material; for example, it can be 0.1 times, 0.3 times, 0.5 times, 0.8 times, 1.0 times, 1.2 times, 1.5 times, 1.8 times or 2.0 times.

[0025] More preferably, the raw material of the counter electrode further includes a binder, and the mass ratio of Wu to the binder is 1:(1-5); 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:.5, 1:4, 1:4.5 or 1:5.

[0026] In some preferred embodiments of the present invention, the reference electrode is adhered to the surface of the solid electrolyte membrane using the above-mentioned method 2).

[0027] Preferably, the solid electrolyte membrane comprises a double perovskite material, Al2O3 and a binder, and the mass ratio of the double perovskite material, Al2O3 and the binder is 1:(0.5-2):(1-5).

[0028] Further preferably, the double perovskite material is Cs2NaBiCl6.

[0029] Further preferably, the mass ratio of the double perovskite material, Al2O3 and binder is 1:(0.5-1.5):(1-4); including but not limited to 1:1:1, 1:1:2, 1:1:3 or 1:1:4.

[0030] Preferably, the reference electrode is a Ti / TiO2 electrode.

[0031] Preferably, the counter electrode is a Wu electrode.

[0032] Further preferably, the counter electrode further comprises Al2O3, and the mass ratio of Wu to Al2O3 is 1:(0.5-2); including but not limited to 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2.0.

[0033] Preferably, the binder is any one or more selected from silica sol, zirconium sol, and aluminum sol.

[0034] More preferably, the binder is silica sol.

[0035] Preferably, the fixing further comprises separately sintering the solid electrolyte membrane after the electrodes are adhered, so that the electrodes are fixed to the surface of the solid electrolyte membrane.

[0036] Further preferably, the separate sintering is to adhere a single electrode to the surface of the solid electrolyte membrane and then sinter it, and then continue to adhere the next electrode and sinter and fix it.

[0037] More preferably, the order of adhering the electrodes is: first adhering the working electrode to the surface of the solid electrolyte membrane for sintering, then adhering the reference electrode to the surface of the solid electrolyte membrane for sintering, and finally adhering the counter electrode to the surface of the solid electrolyte membrane for sintering.

[0038] Preferably, the sintering temperature of the working electrode is 1400-1600°C, including but not limited to 1400°C, 1450°C, 1500°C, 1550°C or 1600°C.

[0039] Preferably, the sintering time of the working electrode is 5 to 10 hours, including but not limited to 5 hours, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours.

[0040] Preferably, the sintering temperature of the reference electrode is 400-600°C, including but not limited to 400°C, 450°C, 500°C, 550°C or 600°C.

[0041] Preferably, the sintering time of the reference electrode is 1 to 5 hours, including but not limited to 1 hour, 2 hours, 3 hours, 4 hours or 5 hours.

[0042] Preferably, the sintering temperature of the counter electrode is 400-600°C, including but not limited to 400°C, 450°C, 500°C, 550°C or 600°C.

[0043] Preferably, the sintering time of the counter electrode is 5 to 10 hours, including but not limited to 1 hour, 2 hours, 3 hours, 4 hours or 5 hours.

[0044] Preferably, the area of ​​the working electrode is 40% to 90% based on the surface area of ​​the adhesion surface of the solid electrolyte membrane; including but not limited to 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% or 90%.

[0045] Preferably, based on the surface area of ​​the adhesion surface of the solid electrolyte membrane, the area of ​​the counter electrode is 40% to 90%; including but not limited to 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% or 90%.

[0046] Preferably, based on the surface area of ​​the adhesion surface of the solid electrolyte membrane, the area of ​​the reference electrode is 5-10%; including but not limited to 5%, 6%, 7%, 8%, 9% or 10%.

[0047] Preferably, the thickness of the catalyst layer is 50-100 nm.

[0048] Further preferably, the thickness of the catalyst layer is 70 to 90 nm, including but not limited to 70 nm, 72 nm, 75 nm, 78 nm, 80 nm, 82 nm, 85 nm, 88 nm or 90 nm.

[0049] Preferably, the solid electrolyte membrane has a thickness of 0.5 to 1.5 mm.

[0050] Further preferably, the thickness of the solid electrolyte membrane is 0.5 to 1.0 mm, including but not limited to 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm or 1.0 mm.

[0051] Preferably, the thickness of the working electrode is 0.1-0.5 mm; for example, it can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm or 0.5 mm.

[0052] Further preferably, the thickness of the working electrode is 0.2-0.3 mm.

[0053] Preferably, the thickness of the counter electrode is 0.1-0.5 mm; for example, it may be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm or 0.5 mm.

[0054] Further preferably, the thickness of the counter electrode is 0.2-0.3 mm.

[0055] Preferably, the thickness of the reference electrode is 0.1-0.5 mm; for example, it can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm or 0.5 mm.

[0056] A third aspect of the present invention provides an application of the electrochemical sensor described above for detecting SiCl 4 gas within a temperature range of 1000-1500°C.

[0057] A fourth aspect of the present invention provides a method for using the electrochemical sensor to detect SiCl4 gas concentration, the method comprising: connecting each electrode of the electrochemical sensor to a signal processing device, applying a voltage to generate a current signal; and using a standard curve method to obtain the concentration of the SiCl4 gas to be measured based on a SiCl4 gas concentration-current response standard curve and the current response value of the SiCl4 gas to be measured.

[0058] As described above, the electrochemical sensor for SiCl4 gas detection and the preparation method thereof of the present invention have the following beneficial effects:

[0059] 1. Excellent high-temperature resistance: The present invention uses refractory metals and perovskite electrolytes as working electrodes, which can work stably for a long time in high-temperature environments (1000-1500°C), effectively overcoming the problem that traditional sensor materials are prone to failure at high temperatures, and significantly improving the service life and reliability of the sensor.

[0060] 2. High detection accuracy: By optimizing the combination of electrode materials, catalysts and electrolytes, and adopting a three-electrode structure design, the influence of electrode polarization and external interference is reduced, making the sensor have extremely high accuracy in detecting SiCl4 gas concentration.

[0061] 3. Fast response speed: By introducing a catalyst on the surface of the working electrode and setting up a counter electrode, the reaction rate of SiCl4 gas on the electrode surface is greatly accelerated, the electrode polarization effect is reduced, and the rapid real-time monitoring of SiCl4 gas concentration can be achieved.

[0062] 4. Good selectivity: Due to the use of a specific chloride ion conductor electrolyte and catalyst, the sensor has a high degree of selectivity for SiCl4 gas, and can effectively eliminate the influence of common interfering gases (such as CO, CO2, O2, HCl, etc.) in high-temperature environments. In complex environments containing multiple interfering gases, the sensor's detection results for SiCl4 gas are not significantly interfered with, ensuring the reliability of the test results.

[0063] 5. Reasonable structural design: The three-electrode structure design gives the sensor better stability and anti-interference ability, while facilitating connection with external circuits and signal processing. In addition, the modular design of the sensor components facilitates installation, maintenance and replacement, reducing usage costs and improving adaptability to industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 Shown is a schematic diagram of the structure of the electrochemical sensor prepared in Example 1 of the present invention; the names of the components are: 1. reference electrode, 2. catalyst layer, 3. working electrode, 4. electrolyte membrane, 5. counter electrode.

[0065] Figure 2 Shown is a circuit diagram for measuring the current generated by the electrochemical sensor in Example 2 of the present invention; the names of the components are: 1. reference electrode, 2. catalyst layer, 3. working electrode, 4. electrolyte membrane, 5. counter electrode.

[0066] Figure 3 Shown is a schematic diagram of the specific electrical signal generation, collection and processing methods of the electrochemical sensor in Example 2 of the present invention. DETAILED DESCRIPTION

[0067] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0068] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0069] Furthermore, it should be understood that the one or more method steps mentioned in the present invention do not exclude the presence of other method steps before or after the combination step, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified. It should also be understood that the combination connection relationship between one or more devices / apparatuses mentioned in the present invention does not exclude the presence of other devices / apparatuses before or after the combination device / apparatus, or the insertion of other devices / apparatuses between two explicitly mentioned devices / apparatuses. Furthermore, unless otherwise specified, the numbering of each method step is merely a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of the present invention. Changes or adjustments to their relative relationships, without substantially changing the technical content, should also be considered within the scope of the present invention.

[0070] Before further describing the specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific specific embodiments described below; it should also be understood that the terms used in the examples of the present invention are for describing specific specific embodiments rather than for limiting the scope of protection of the present invention; in the present specification and claims, unless otherwise expressly stated herein, the singular forms "a", "an" and "the" include plural forms.

[0071] When the embodiments provide numerical ranges, it should be understood that, unless otherwise specified in the present invention, both endpoints of each numerical range and any numerical value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those generally understood by those skilled in the art. In addition to the specific methods, equipment, and materials used in the embodiments, according to the understanding of the prior art by those skilled in the art and the description of the present invention, any methods, equipment, and materials of the prior art similar or equivalent to the methods, equipment, and materials described in the embodiments of the present invention may also be used to implement the present invention.

[0072] The applicant of the present invention has discovered through extensive experimental research that using refractory metals and double permeate titanium materials as working electrodes can achieve selective detection of SiCl4 gas under high temperature conditions; the working electrode, counter electrode, and reference electrode are adhered to the surface of a solid electrolyte diaphragm to form an electrochemical sensor; the electrochemical sensor has improved stability and anti-interference capabilities, and can operate stably for a long time at 1000-1500°C, effectively overcoming the problem of traditional sensor materials being prone to failure at high temperatures, and significantly improving the service life and reliability of the sensor.

[0073] The working principle of the electrochemical sensor of the present invention is as follows: the target SiCl4 gas reaches the electrochemical sensor by diffusion, and the following reduction process occurs on the surface of the working electrode:

[0074] SiCl4+2e - →SiCl22-↑+2Cl-;

[0075] The following oxidation process occurs on the counter electrode surface:

[0076] 2Cl-→Cl2↑+2e - ;

[0077] Electrons flow from the working electrode to the counter electrode through an external circuit, forming a current loop. The concentration of SiCl4 gas is calculated by the intensity of the current signal.

[0078] In order to facilitate understanding of the embodiments of the present application, first Figure 1 Detailed description. Figure 1 A schematic diagram of an electrochemical sensor for SiCl4 gas detection in an embodiment of the present invention is shown.

[0079] The electrochemical sensor includes a reference electrode 1, a catalyst layer 2, a working electrode 3, an electrolyte membrane 4, and a counter electrode 5. The electrolyte membrane 4 serves as a substrate, with the working electrode 3 and the counter electrode 5 fixed to either side of the electrolyte membrane 4, respectively. The reference electrode 1 is fixed adjacent to the working electrode 3 and spaced apart from each other. The catalyst layer 2 is fixed to the surface of the working electrode 3.

[0080] The preparation method of the electrochemical sensor of the present invention comprises the following steps:

[0081] S1. Coating the working electrode onto the surface of the solid electrolyte membrane, sintering at 1400-1600° C. for 5-10 hours to fix the working electrode onto the surface of the solid electrolyte membrane;

[0082] S2, the catalyst layer is deposited on the surface of the working electrode by magnetron sputtering, and the vacuum degree of magnetron sputtering is 10 -4 ~10 -5 Pa;

[0083] S3, bonding the reference electrode to the surface of the solid electrolyte membrane through a binder, sintering at 400-600° C. for 1-5 hours, and fixing the reference electrode to the surface of the solid electrolyte membrane;

[0084] S4. Coat the counter electrode on the surface of the solid electrolyte membrane, sinter at 400-600° C. for 1-5 hours, and fix the counter electrode to the surface of the solid electrolyte membrane.

[0085] In each of the above steps, an adhesive is used to adhere the electrode to the surface of the solid electrolyte membrane.

[0086] The above-mentioned adhesive is used in the form of an adhesive solution.

[0087] The binder is any one or more selected from silica sol, zirconium sol and aluminum sol.

[0088] The solvent in the binder solution is any one or two selected from ethanol and water.

[0089] Based on the total mass of the binder solution, the concentration of the binder in the above binder solution is 20-30wt%, including but not limited to 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt% or 30wt%.

[0090] The preparation method of the above-mentioned solid electrolyte membrane includes: mixing Cs2NaBiCl6 powder and Al2O3 in a mass ratio of 1:(0.5~2) to form a mixed powder, adding a binder solution 8 to 10 times the total mass of the mixed powder to the mixed powder, stirring to form a mixed slurry, pressing the mixed slurry into shape, and sintering at 400 to 600°C for 10 to 15 hours to obtain a solid electrolyte membrane.

[0091] The pressure during compression molding of the solid electrolyte membrane is 10 to 20 MPa, including but not limited to 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa, 15 MPa, 16 MPa, 17 MPa, 18 MPa, 19 MPa or 20 MPa.

[0092] The preparation method of the Cs2NaBiCl6 powder used above includes: dispersing BiCl3 and NaCl in HCl solution, stirring at 60-80°C for 10-30 minutes, adding CsCl to the solution to produce a precipitate, continuing to stir for 10-30 minutes to terminate the reaction, filtering, washing, and drying the precipitate to obtain Cs2NaBiCl6 powder.

[0093] The molar ratio of BiCl3 to NaCl is 1:(0.5-2); for example, it can be 1:0.5, 1:0.8, 1:1.0, 1:1.2, 1:1.5, 1:1.8 or 1:2.

[0094] The molar ratio of BiCl3 to CsCl is 1:(1.5-5); for example, it can be 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 or 1:5.

[0095] Based on 1 mmol of BiCl3, the amount of the HCl solution added is 2 to 10 mL; for example, it can be 2 mL, 3 mL, 4 mL, 5 mL, 6 mL, 7 mL, 8 mL, 9 mL or 10 mL.

[0096] The mass fraction of HCl in the above HCl solution is 5-10%, for example, it can be 5%, 6%, 7%, 8%, 9% or 10%.

[0097] The solution used for washing the precipitate is water.

[0098] The drying temperature is 50-80°C; for example, it can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C.

[0099] The method for coating the working electrode on the surface of the solid electrolyte membrane is to mix the raw materials of the working electrode to form a mixed slurry, and then coat the mixed slurry on the surface of the solid electrolyte membrane.

[0100] The specific method for preparing the mixed slurry of the working electrode includes: mixing metal powder, Cs2NaBiCl6 powder and Al2O3 in a mass ratio of 1:(2~3):(3~4) to form a mixed powder, adding a binder solution to the mixed powder, and stirring to form a mixed slurry.

[0101] The method for bonding the reference electrode to the surface of the solid electrolyte membrane is as follows: bonding the reference electrode to the surface of the solid electrolyte membrane via a binder solution.

[0102] The preparation method of the reference electrode includes: oxidizing a titanium wire to generate a TiO2 oxide layer, washing and drying the titanium wire with water, and then annealing the titanium wire at 400-600°C for 0.5-2h to obtain a Ti / TiO2 electrode.

[0103] The titanium wire oxidation method comprises electrochemically oxidizing the titanium wire using the titanium as an anode to form a TiO2 oxide layer on the titanium surface. Specifically, the titanium wire is used as the anode and a platinum sheet is used as the cathode. The oxidation is carried out at a voltage of 50 to 70 volts for 10 to 50 minutes in an ethylene glycol solution containing 0.1 to 0.5 wt% ammonium fluoride and 1 to 5 vol% water.

[0104] The method for coating the counter electrode on the surface of the solid electrolyte membrane is to mix the raw materials of the counter electrode to form a mixed slurry, and then coat the mixed slurry on the surface of the solid electrolyte membrane.

[0105] The method for preparing the mixed slurry of the above-mentioned counter electrode includes: mixing Wu powder and Al2O3 in a mass ratio of 1:(0.5-2) to form a mixed powder, adding a binder solution to the mixed powder, and stirring to form a mixed slurry.

[0106] Example 1

[0107] This embodiment 1 provides a specific method for preparing an electrochemical sensor, which specifically includes the following steps:

[0108] Step 1: Preparation of solid electrolyte membrane

[0109] Disperse 0.5 mmol BiCl₃ and 0.5 mmol NaCl in 3 mL of 5% HCl and stir at 80°C for 20 minutes to ensure uniform dispersion. Subsequently, add 1 mmol CsCl to the solution, which will immediately form a white precipitate. Continue stirring for 20 minutes to ensure sufficient reaction. After the reaction, the white precipitate is centrifuged, washed three times with water, and then dried at 60°C to obtain Cs₂NaBiCl₆ powder.

[0110] Cs2NaBiCl6 powder and Al2O3 are mixed in a 1:1 ratio to form a mixed powder. Silica sol is dissolved in water to create a 25wt% silica sol solution. This solution is then added at a solid-to-liquid ratio of 1:5 and stirred to form a uniform slurry. The slurry is poured into a mold and pressed under a pressure of 10-20 MPa to form an electrolyte green body with a thickness of 0.6-0.8 mm. The green body is then sintered in a high-temperature furnace at 500°C for 12 hours to produce a dense solid electrolyte separator.

[0111] Step 2: Preparation of working electrode

[0112] Tantalum powder (purity ≥99.95%) and Cs2NaBiCl6 powder are mixed in a mass ratio of 3:7 to obtain a mixture. An equal amount of Al2O3 and an equal amount of 25wt% silica sol aqueous solution are added to the mixture and the mixture is thoroughly ground to form a uniform mixed slurry. The mixed slurry is coated on one side of the Cs2NaBiCl6 electrolyte membrane with a coating thickness of 0.2-0.3mm. The coated membrane is then placed in a high-temperature furnace and sintered at 1500°C for 8 hours to form a solid Ta-Cs2NaBiCl6 metal-ceramic structure working electrode with the tantalum and Cs2NaBiCl6.

[0113] The iridium (Ir) catalyst layer was further deposited on the surface of the working electrode using magnetron sputtering technology. The prepared working electrode was placed in a vacuum sputtering device with a high-purity iridium target as the source and a vacuum degree of 10 -4 Under the condition of Pa, an iridium catalyst layer with a thickness of 80 nm was deposited on the surface of the working electrode by controlled sputtering.

[0114] Step 3: Preparation of reference electrode

[0115] A titanium wire (0.1-0.3 mm in diameter) was used as the anode and a platinum sheet as the cathode. A TiO2 oxide layer was generated by anodic oxidation at 60 V for 30 minutes in an ethylene glycol solution containing 0.32 wt% ammonium fluoride and 2.7 vol% water using a potentiostat.

[0116] After anodization, the electrode was cleaned with water, dried, and then annealed at 500°C for 1 hour to improve the crystallinity of the oxide layer.

[0117] The prepared Ti / TiO2 electrode was fixed to the other side of the electrolyte membrane using silica sol. The fixed membrane was placed in a high-temperature furnace and sintered at 500°C for 3 hours to firmly bond the Ti / TiO2 to the electrolyte membrane, forming a stable Ti / TiO2 reference electrode.

[0118] Step 4: Preparation of the Counter Electrode

[0119] Tungsten powder (purity ≥99.95%) is mixed with an equal amount of Al2O3 to form a mixed powder. A 25wt% silica sol aqueous solution is added at a solid-liquid mass ratio of 1:5, and the mixture is thoroughly ground to form a mixed slurry. The mixed slurry is coated on the side of the Cs2NaBiCl6 electrolyte membrane near the working electrode, with a coating thickness of 0.2-0.3mm. The coated membrane is then placed in a high-temperature furnace and sintered at 500°C for 8 hours to form a solid tungsten counter electrode.

[0120] The schematic diagram of the electrochemical sensor prepared through the above steps is shown in Figure 1 As shown, the working electrode and the reference electrode are located on the upper layer of the Cs2NaBiCl6 electrolyte membrane, and the counter electrode is located on the lower layer of the Cs2NaBiCl6 electrolyte membrane.

[0121] Example 2

[0122] This embodiment 2 is to connect the electrochemical sensor prepared in embodiment 1 to the external signal processing module. The specific connection method is as follows: Figure 3 shown. Figure 2 This is a schematic diagram of the current loop generated by the electrochemical sensor during a specific test process.

[0123] The electrochemical sensor in Example 1 is connected to an external signal processing circuit via high-temperature resistant wires. The sensor is encapsulated with a high-temperature resistant alumina packaging material to ensure that the electrodes and electrolyte membrane inside the sensor are not affected by the external atmosphere in a high-temperature environment, while also ensuring that the sensor has good mechanical strength and electrical insulation properties. The specific electrical signal acquisition and processing methods are as follows:

[0124] S1. Signal Acquisition: Connect the working electrode, reference electrode, and counter electrode to the data acquisition module via high-temperature-resistant wires. The data acquisition module utilizes a high-precision electrochemical workstation, capable of real-time acquisition of the potential difference (voltage signal) between the working and reference electrodes, as well as the current signal in the circuit. To minimize interference during signal transmission, the wires utilize a double-layer shielding structure, with an outer layer of high-temperature-resistant braided metal mesh and an inner layer of ceramic fiber material with excellent insulating properties.

[0125] S2. Signal Preprocessing: The collected raw electrical signals may contain noise and interference, requiring preprocessing. The preprocessing circuit includes a filter circuit and an amplifier circuit. The filter circuit uses a high-temperature LC filter circuit to effectively filter out high-frequency noise. The amplifier circuit uses a low-noise, high-gain operational amplifier to amplify the weak electrical signal to an appropriate voltage range for subsequent processing.

[0126] S3. Analog-to-digital conversion (ADC): The pre-processed analog electrical signals need to be converted into digital signals before they can be processed by the microprocessor. An ADC chip is used to convert the analog voltage and current signals into digital signals and transmit them to the microprocessor via the SPI communication protocol.

[0127] S4. Data Processing and Calculation: After receiving the digital electrical signal, the microprocessor performs data processing and calculation, converting the electrical signal into a SiCl4 gas concentration value. The calculated SiCl4 gas concentration value is displayed in real time on the LCD screen for easy viewing by the operator.

[0128] S5. Internal Sensor Wiring: Inside the sensor, the working electrode, reference electrode, and counter electrode are connected to the sensor's wiring terminals via high-temperature-resistant platinum wires. To prevent short circuits and interference between the electrodes, the wires are appropriately spaced and insulated with ceramic sleeves. The wiring terminals are made of heat-resistant and corrosion-resistant metal materials to ensure reliable connection to external circuits.

[0129] S6. External wiring: The sensor's external wiring primarily consists of signal transmission lines and power lines. The signal transmission lines utilize double-shielded, high-temperature-resistant cables to connect the sensor's wiring terminals to the data acquisition module. The power lines also utilize high-temperature-resistant cables to provide a stable power source for the data acquisition module, microprocessor, and other devices. Overvoltage protection and filtering circuits are installed at the power input to prevent power supply interference from affecting the system.

[0130] S7. Line Layout Optimization: To reduce electromagnetic interference, signal transmission lines and power lines are laid out separately, and parallel routing is avoided as much as possible. In environments with strong electromagnetic interference, such as high-temperature furnaces, the lines are shielded with metal cable ducts to further improve the system's anti-interference capabilities.

[0131] Example 3

[0132] This Example 3 is a specific performance test of the electrochemical sensor, including: high temperature stability, concentration response capability, response time and selectivity.

[0133] First, we constructed a high-temperature gas testing device. Specifically, we constructed a high-temperature gas detection experimental platform, which primarily includes a high-temperature furnace, a gas distribution system, a gas flow control system, and a data acquisition and processing system. The high-temperature furnace uses a resistance-heated furnace, capable of providing a stable high-temperature environment of 1000-1500°C. The gas distribution system utilizes a mass flow controller, capable of accurately preparing SiCl₄ standard gas of varying concentrations and mixed gases containing interfering gases. The data acquisition and processing system utilizes an electrochemical workstation, which measures the sensor's electrical signals, such as potential and current, and collects and analyzes the data in real time.

[0134] The standard curve method is used to detect SiCl₄ gas concentration. First, 10 SiCl₄ standard gases of different concentrations (5ppm, 50ppm, 100ppm, 200ppm, 300ppm, 500ppm, 800ppm, 1000ppm, 1200ppm, and 1500ppm) are prepared. The electrochemical sensor is used to measure the current signal response at different concentrations. A standard curve is plotted with concentration as the horizontal axis and current signal as the vertical axis. This standard curve is used for subsequent detection.

[0135] The specific performance test methods and results are as follows:

[0136] 1. High temperature stability test: Place the sensor in a high temperature furnace, gradually increase the temperature in the range of 1000-1500℃ at intervals of 20℃, maintain each temperature point for 30 minutes, introduce SiCl4 standard gas with a concentration of 500ppm, measure the output signal of the sensor at different temperatures, and study the temperature stability of the sensor and the influence of temperature on the detection performance.

[0137] After the SiCl₄ standard gas was introduced, the sensor responded rapidly. At each temperature point, the sensor's output signal remained stable for 30 minutes, with a signal fluctuation range of less than 2%. Throughout the entire temperature measurement process, the sensor signal fluctuation range remained less than 5%. These results demonstrate the electrochemical sensor's excellent high-temperature stability.

[0138] 2. Concentration response test: Under a constant temperature of 1500℃, SiCl4 standard gas with a concentration range of 10-1000ppm is prepared through the gas distribution system and introduced into the sensor detection chamber in sequence. Each concentration point is maintained for 15 minutes. The current signal of the sensor is measured, and a relationship curve between the sensor output signal and the SiCl4 gas concentration is established to evaluate the detection accuracy and linear range of the sensor.

[0139] The results show that within the concentration range of 10-1000ppm, the sensor output signal shows a good linear relationship with the SiCl4 gas concentration, with a correlation coefficient exceeding 0.995 and a detection error of less than ±2%, proving that the sensor has excellent detection accuracy and can accurately detect SiCl4 gas at different concentrations.

[0140] 3. Response Time Test: At 1500°C, first introduce high-purity nitrogen to stabilize the sensor. Then quickly switch to 500ppm SiCl4 standard gas. Record the time required for the sensor output signal to reach 90% of the stable value as the sensor response time. Repeat the test three times and take the average value. The final calculated response time is 3.5s, indicating that the sensor has a fast response capability.

[0141] 4. Selectivity test: At 1500°C, different interfering gases (CO, CO2, O2, HCl, all at 500ppm) were prepared and introduced into the sensor detection chamber. The sensor's output signal to the interfering gases was measured and compared with the detection results of 500ppm SiCl4 gas to evaluate the sensor's selectivity to SiCl4 gas. The results showed that the sensor showed no response to any of the interfering gases, indicating its excellent selectivity.

[0142] In summary, the electrochemical sensor prepared in this application is suitable for specifically detecting the concentration of SiCl4 gas in a high-temperature environment (1000-1500°C). It has excellent high-temperature resistance, high detection accuracy, fast response speed, and good selectivity, ensuring the reliability of the detection results and has broad application prospects.

[0143] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form or substance. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention. Any equivalent changes, modifications and evolutions made by technicians familiar with this profession without departing from the spirit and scope of the present invention by using the technical content disclosed above are all equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A working electrode for SiCl4 gas detection, characterized in that: The working electrode comprises metal and double perovskite material, and the mass ratio of the metal to the double perovskite material is 1:(1-5).

2. The working electrode according to claim 1, characterized in that The working electrode further comprises Al2O3, wherein the amount of Al2O3 is 0.5 to 2 times the total mass of the metal and the double perovskite material; And / or, the metal is any one or two selected from Ta and Ti; And / or, the double perovskite material is Cs2NaBiCl6; And / or, the working electrode further includes a catalyst layer.

3. The working electrode according to claim 2, characterized in that The catalyst is Ir; And / or, the catalyst layer is fixed on the surface of the working electrode; And / or, the catalyst layer has a thickness of 50 to 100 nm.

4. An electrochemical sensor, characterized in that The electrochemical sensor comprises: a solid electrolyte membrane, a working electrode according to any one of claims 1 to 3, a reference electrode, and a counter electrode; the working electrode, reference electrode, and counter electrode are fixed to the surface of the solid electrolyte membrane.

5. The electrochemical sensor according to claim 4, characterized in that The fixing includes using a binder to adhere each electrode to the surface of the solid electrolyte membrane, and the adhesion method includes any one or both of the following methods: 1) doping the binder into the electrode raw material and coating the electrode on the surface of the solid electrolyte membrane; 2) applying a binder to the surface of the electrode and adhering the electrode to the surface of the solid electrolyte membrane; And / or, the solid electrolyte membrane comprises a double perovskite material, Al2O3 and a binder, and the mass ratio of the double perovskite material, Al2O3 and the binder is 1:(0.5-2):(1-5); And / or, the reference electrode is a Ti / TiO2 electrode; And / or, the counter electrode is a Wu electrode.

6. The electrochemical sensor according to claim 5, characterized in that The binder is any one or more selected from silica sol, zirconium sol, and aluminum sol; And / or, the fixing further comprises separately sintering the solid electrolyte membrane after the electrodes are adhered, so that the electrodes are fixed to the surface of the solid electrolyte membrane.

7. The electrochemical sensor according to claim 6, characterized in that The sintering temperature of the working electrode is 1400-1600°C; And / or, the sintering time of the working electrode is 5 to 10 hours; and / or, the sintering temperature of the reference electrode is 400-600° C.; and / or, the reference electrode is sintered for 1 to 5 hours; and / or, the sintering temperature of the counter electrode is 400-600° C.; And / or, the sintering time of the counter electrode is 5 to 10 hours.

8. The electrochemical sensor according to claim 5, characterized in that The double perovskite material is Cs2NaBiCl6; And / or, the counter electrode further comprises Al2O3, and the mass ratio of Wu to Al2O3 is 1:(0.5-2).

9. Use of the electrochemical sensor according to any one of claims 4 to 8 for detecting SiCl4 gas concentration in a temperature range of 1000-1500°C.

10. A method for detecting SiCl4 gas concentration using the electrochemical sensor according to any one of claims 4 to 8, characterized in that: The method includes: connecting each electrode of the electrochemical sensor to a signal processing device, applying a voltage to generate a current signal; and using a standard curve method to obtain the concentration of the SiCl4 gas to be measured based on a SiCl4 gas concentration-current response standard curve and a current response value of the SiCl4 gas to be measured.

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