Titanium dioxide modified graphene gas sensor, preparation method thereof and application thereof in detection of sf6 decomposition components

Abstract

The application discloses a titanium dioxide modified graphene gas sensitive sensor and a preparation method thereof and application of the sensor in SF6 decomposition component detection. n The graphene structure is uniformly dispersed on the surface of the graphene, n=1, 2, 3 or 4, is used for specifically adsorbing SF6 decomposition components and converting concentration changes of the decomposition components into resistance change signals; and the electrode lead is connected to the interdigital electrode substrate and is used for receiving the resistance change signals of the sensitive material layer via the interdigital electrode substrate and transmitting the resistance change signals to an external detection device. The application can solve the problems of existing SF6 decomposition component detection equipment, such as large size, high cost, low detection efficiency, insufficient gas sensitive performance of a traditional graphene sensor, imperfect preparation process and the like, and realizes high-precision, rapid and stable detection of SF6 decomposition components.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a titanium dioxide modified graphene gas sensor, its preparation method, and its application in the detection of SF6 decomposition components. Background Technology

[0002] Sulfur hexafluoride (SF6) is widely used in gas-insulated equipment (GIS) of power systems due to its excellent insulation strength, arc-extinguishing ability, and chemical stability, serving as a key insulating medium for high-voltage power system operation. During long-term operation, insulation defects (such as metal particles, air gaps, and metal protrusions) or overvoltages (lightning overvoltages, switching overvoltages) can easily trigger partial discharge, spark discharge, or arc discharge faults. These discharge faults lead to the decomposition of SF6 gas, producing characteristic decomposition components such as H2S, SO2, SOF2, and SO2F2. These components have extremely poor insulation properties, further exacerbating equipment insulation failure and potentially causing power grid outages in severe cases. Therefore, accurate detection of the composition and concentration of SF6 decomposition components is crucial for determining the type and severity of partial discharge faults in GIS equipment and ensuring the safe and stable operation of the power system.

[0003] Currently, the main methods for detecting SF6 decomposition components include photoacoustic spectroscopy, gas chromatography, infrared absorption spectroscopy, and gas sensor methods. Among these, photoacoustic spectroscopy is easily affected by external environmental interference, impacting its accuracy; gas chromatography and infrared absorption spectroscopy suffer from problems such as bulky equipment, high cost, and complex operation procedures, making it difficult to achieve on-site real-time monitoring; gas sensor methods, with their advantages of small size, low cost, fast response speed, and real-time monitoring capability, have become the mainstream technology for detecting SF6 decomposition components.

[0004] Graphene, as a two-dimensional nanomaterial, possesses excellent conductivity and an ultra-large specific surface area, making it an ideal substrate material for gas sensing. However, intrinsic graphene exhibits poor selectivity and low response values ​​in its gas-sensing response to SF6 decomposition components, limiting its practical application in this field. Transition metal oxides (such as TiO2) possess good chemical stability and catalytic activity, and their gas-sensing performance can be effectively improved through doping modification. However, existing technologies for preparing titanium dioxide-modified graphene generally suffer from problems such as uneven doping and unstable gas-sensing performance, and there are few targeted optimization designs for the detection of SF6 decomposition components, making it difficult to meet the stringent requirements of power systems for detection accuracy, response speed, and stability. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this paper provides a titanium dioxide-modified graphene gas sensor, its preparation method, and its application in the detection of SF6 decomposition components. This addresses the problems of large size, high cost, low detection efficiency of existing SF6 decomposition component detection equipment, as well as the insufficient gas-sensing performance and imperfect preparation process of traditional graphene sensors, thereby achieving high-precision, rapid, and stable detection of SF6 decomposition components.

[0006] To achieve the above objectives, the present invention is implemented using the following technical solution: According to a first aspect of the present invention, a titanium dioxide-modified graphene gas sensor is provided. The gas sensor comprises: Interdigitated electrode substrate; A sensitive material layer, coated on the surface of the interdigitated electrode substrate, comprises a titanium dioxide cluster-doped graphene sensitive material; the mass ratio of titanium dioxide clusters to graphene in this sensitive material is 70:30 to 80:20, and the titanium dioxide clusters are in the form of (TiO2). n - Graphene structures are uniformly dispersed on the graphene surface, n=1, 2, 3 or 4, which are used to specifically adsorb SF6 decomposition components and convert the concentration changes of decomposition components into resistance change signals. Electrode leads are connected to the interdigitated electrode substrate for receiving the resistance change signal of the sensitive material layer via the interdigitated electrode substrate and transmitting it to an external detection device.

[0007] Furthermore, the thickness of the sensitive material layer is 5-10 μm.

[0008] Furthermore, the mass ratio of titanium dioxide clusters to graphene in the sensitive material is 75:25.

[0009] According to a second aspect of the present invention, a method for preparing a titanium dioxide-modified graphene gas sensor as described in the first aspect of the present invention is provided, the method comprising the following steps: Provide interdigitated electrode substrate; Preparation of titanium dioxide cluster-doped graphene sensitive materials; The metal interdigitated electrodes in the interdigitated electrode substrate are wiped with ethanol, rinsed with deionized water, and dried with nitrogen to remove surface oil and impurities. The titanium dioxide cluster-doped graphene-sensitive material was mixed with ethanol and ultrasonically dispersed to form a dispersion. The metal interdigitated electrode is heated, and the dispersion is uniformly coated on the surface of the metal interdigitated electrode, with the coating thickness controlled at 5-10 μm. The sprayed interdigitated electrode substrate was placed in an oven for drying to obtain the titanium dioxide modified graphene gas sensor.

[0010] Furthermore, the preparation of the titanium dioxide cluster-doped graphene sensitive material includes the following steps: Preparation of intrinsic graphene powder; Intrinsic graphene powder was added to ultrapure water and ultrasonically dispersed to obtain a uniformly dispersed graphene dispersion. Ti(SO4)2 solid was dissolved in deionized water and stirred until completely dissolved to obtain a Ti(SO4)2 solution. The graphene dispersion was mixed with the Ti(SO4)2 solution, and after ultrasonic treatment at room temperature, urea solution was added, and after stirring evenly, the mixture was transferred to a reaction vessel for hydrothermal reaction. The reaction product of the hydrothermal reaction was washed repeatedly with deionized water and anhydrous ethanol to remove residual impurities, and then dried to obtain the titanium dioxide cluster-doped graphene sensitive material; wherein the mass ratio of titanium dioxide clusters to graphene is 70:30~80:20, and the titanium dioxide clusters are in the form of (TiO2). n -Graphene structures are uniformly dispersed on the graphene surface, n=1, 2, 3 or 4.

[0011] Furthermore, the hydrothermal reaction temperature is 90~100℃ and the reaction time is 8~12 hours.

[0012] Furthermore, the preparation of intrinsic graphene powder includes the following steps: Measure 98% concentrated sulfuric acid and 85% concentrated phosphoric acid in a volume ratio of 8:2 to 9.5:0.5, mix them thoroughly, and place them in a reaction vessel to obtain a mixed acid. Add graphite powder to the mixed acid, stir evenly, and then place the reaction vessel in a constant temperature stirring device at 48-52℃ to construct the reaction system; Potassium permanganate was slowly added to the reaction system in a controlled manner to maintain the temperature of the reaction system at 48-52℃ and avoid local overheating. After adding potassium permanganate, continue stirring the reaction. Then slowly add diluted hydrogen peroxide until the reaction system turns bright yellow and no bubbles are produced, then terminate the oxidation reaction. The reaction product of the oxidation reaction was diluted, centrifuged and washed until the pH was 5.5-6.5, and then dried to obtain intrinsic graphene powder.

[0013] Furthermore, uniformly coating the dispersion onto the surface of the interdigitated metal electrode includes: The dispersion is coated onto the surface of the interdigitated electrode using spraying, dripping, or spin coating methods.

[0014] According to a third aspect of the present invention, an apparatus for detecting SF6 decomposition components is provided. The apparatus includes: The titanium dioxide modified graphene gas sensor as described in the first aspect of the present invention is used to adsorb SF6 decomposition components and convert the concentration change of the decomposition components into a resistance change signal. An electrochemical workstation is connected to the gas sensor via electrode leads for real-time monitoring of the resistance change signal. Dynamic gas mixing instrument is used to prepare standard gases of SF6 decomposition components at different concentrations; The test gas chamber is used to house the gas-sensitive sensor and the target detection gas, ensuring the sealing and stability of the detection process; The data processing module is used to receive data related to the resistance change signal transmitted by the electrochemical workstation, calculate the gas-sensitive response value, and output the detection result.

[0015] According to a fourth aspect of the present invention, a method for detecting SF6 decomposition components is provided. The method employs the decomposition component detection apparatus as described in the third aspect of the present invention and includes the following steps: An electrochemical workstation was used as the testing equipment and connected to the prepared gas sensor. H2S, SO2, SOF2, and SO2F2 gases with different target concentrations in the range of 10-100ppm were prepared using a dynamic gas mixing instrument with nitrogen as the balance gas as the standard gas for SF6 decomposition components. The gas sensor was placed in the test gas chamber and the gas flow rate was kept constant. Nitrogen gas is introduced into the test chamber. After the resistance change signal of the gas sensor displayed on the electrochemical workstation indicates that the resistance value has stabilized, the stabilized resistance value is recorded as the baseline resistance value R0, and the nitrogen gas introduction is stopped. Select a standard gas of the SF6 decomposition component from various standard gases and introduce it to the target concentration. Record the sensor resistance change in real time until the resistance value stabilizes and record the corresponding resistance value R. Calculate the gas-sensitive response value according to a preset formula: Gas-sensitive response value = |R - R0| / R0 × 100%. Repeat the test multiple times to ensure that the relative standard deviation of the multiple repeated tests is less than a preset deviation threshold. Take the average gas-sensitive response value of the multiple repeated tests as the detection result. After the standard gas detection of each concentration of SF6 decomposition components is completed, nitrogen gas is introduced into the purging chamber for 30 minutes to restore the sensor to the baseline resistance R0.

[0016] The beneficial effects of this invention are that, compared with the prior art, 1. Optimized Sensitive Material Ratio and Structure: A titanium dioxide cluster to graphene mass ratio of 70:30~80:20 is adopted to form a specific (TiO2)n-Graphene (n=1-4) structure. In this specific structure, titanium dioxide exists in the form of extremely small "clusters" rather than large particles, which makes it easier to achieve high dispersion loading on the two-dimensional graphene surface, thus avoiding the problem of uneven doping from the structural root. At the same time, graphene, as a conductive substrate, is responsible for transmitting resistance change signals. Since the titanium dioxide clusters are very small and uniformly dispersed on the graphene surface, they do not form a huge insulating barrier like large particle agglomerates, thus preserving the excellent conductive network of graphene and ensuring that the sensor can sensitively convert chemical signals into resistance signals. Furthermore, the titanium dioxide clusters provide active sites for the specific adsorption of SF6 decomposition components. Uniform dispersion means that, under the same mass ratio, the surface area of ​​titanium dioxide exposed to the gas is maximized, providing more adsorption sites, thereby significantly improving adsorption selectivity and response value.

[0017] 2. Improve the preparation process: By precisely controlling parameters such as the ratio of mixed acid, reaction temperature, and hydrothermal conditions, the problem of uneven doping can be further improved, ensuring the stability of the performance of sensitive materials; 3. Low-cost and miniaturized design: The sensor has a simple structure and low manufacturing cost. The matching detection equipment is small in size and easy to operate, enabling on-site online real-time monitoring and overcoming the limitations of traditional detection methods. 4. High-efficiency detection method design: It enables rapid detection of SF6 decomposition components in the concentration range of 10-100ppm under normal temperature and pressure, with a response time of ≤30 seconds and a recovery time of ≤1 minute, meeting the timeliness requirements of online monitoring; 5. High stability and repeatability: By optimizing the coating process of sensitive materials and the detection process, the relative standard deviation of the sensor in multiple tests is less than the preset deviation threshold (e.g., 5%), ensuring the reliability of the detection results. Attached Figure Description

[0018] Figure 1 This is a flowchart of the preparation process of titanium dioxide cluster-doped graphene sensitive material provided by the present invention; Figure 2 The titanium dioxide cluster-doped graphene sensitive material provided by this invention contains (TiO2). n -Schematic diagram of the fabrication principle of the Graphene structure; Figures 3(a) and 3(b) are, respectively, a perspective view and a bottom view of the titanium dioxide modified graphene gas sensor provided by the present invention; Figure 4 This is an application scenario diagram of the SF6 decomposition component detection device based on the titanium dioxide modified graphene gas sensor provided by the present invention. Figure 5The present invention provides different titanium dioxide clusters ((TiO2)). n -Graphene, n=1, 2, 3 or 4) Total density of states (TDOS) and partial density of states (PDOS) plot of graphene-doped sensitive materials after adsorption of SF6 gas; Figure 6 The present invention provides different titanium dioxide clusters ((TiO2)). n -Graphene, n=1, 2, 3 or 4) The total density of states (TDOS) and partial density of states (PDOS) of graphene-doped sensitive materials after adsorption and decomposition of gas H2S; Figure 7 The present invention provides different titanium dioxide clusters ((TiO2)). n -Graphene, n=1, 2, 3 or 4) Total density of states (TDOS) and partial density of states (PDOS) plot of graphene-doped sensitive materials after adsorption and decomposition of gas SO2; Figure 8 This invention provides different titanium dioxide clusters ((TiO2)). n -Graphene, n=1, 2, 3 or 4) Total density of states (TDOS) and partial density of states (PDOS) plot of graphene-doped sensitive materials after adsorption and decomposition of SOF2 gas; Figure 9 The present invention provides different titanium dioxide clusters ((TiO2)). n -Graphene, n=1, 2, 3 or 4) The total density of states (TDOS) and partial density of states (PDOS) of graphene-doped sensitive materials after adsorption and decomposition of gases SO2 and F2; Figure 10 These are SEM images of sensitive materials containing titanium dioxide clusters and graphene at different mass ratios.

[0019] Explanation of reference numerals in the attached figures: 1-Electrochemical workstation; 2-Connecting cable; 3-Nitrogen generator; 4-Titanium dioxide cluster-doped graphene sensitive material; 5-Test gas chamber; 6-Dynamic gas mixing instrument; 7-Gas circuit switch; 8-Flow regulating valve; 9-Purge and exhaust valve; 10-Circulation pump; 11-Gas cylinder inlet valve; 12-Gas cylinder exhaust valve; 13-Gas cylinder filling port. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, other embodiments obtained by those skilled in the art without creative effort are all within the protection scope of this invention.

[0021] This invention aims to provide a titanium dioxide-modified graphene gas sensor, its preparation method, and its application in the detection of sulfur hexafluoride (SF6) decomposition components. It primarily addresses four problems in existing technologies: First, existing methods for detecting SF6 decomposition components (such as gas chromatography and infrared absorption spectroscopy) suffer from large equipment size, high cost, and complex operation, making real-time online monitoring impossible. Photoacoustic spectroscopy, on the other hand, is susceptible to external interference and lacks accuracy. Second, traditional graphene gas sensors exhibit poor selectivity and low response values ​​for SF6 decomposition components, making accurate identification of target components difficult. Third, existing titanium dioxide-modified graphene preparation processes suffer from uneven doping and unstable gas-sensing performance, affecting the reliability of detection results. Fourth, existing technologies lack specific optimized designs for SF6 decomposition component detection, failing to meet the power system's requirements for detection accuracy, response speed, and long-term stability.

[0022] Overall, this invention optimizes the doping ratio of titanium dioxide clusters and graphene, improves the preparation process to construct sensitive materials with specific structures, and combines standardized detection methods to ultimately achieve high-precision, rapid, and stable detection of SF6 decomposition components, providing reliable technical support for online monitoring of partial discharge faults in SF6-insulated equipment in power systems.

[0023] Example 1 As shown in Figures 3(a) to 3(b), this embodiment provides a titanium dioxide-modified graphene gas sensor. The titanium dioxide-modified graphene gas sensor includes: Interdigitated electrode substrate; A sensitive material layer, coated on the surface of the interdigitated electrode substrate, includes a titanium dioxide cluster-doped graphene sensitive material; the mass ratio of titanium dioxide clusters to graphene in the sensitive material is 70:30~80:20, and the titanium dioxide clusters are uniformly dispersed on the graphene surface in a (TiO2)n-Graphene structure, n=1, 2, 3 or 4, for specifically adsorbing SF6 decomposition components and converting the concentration change of the decomposition components into a resistance change signal; Electrode leads are connected to the interdigitated electrode substrate for receiving the resistance change signal of the sensitive material layer via the interdigitated electrode substrate and transmitting it to an external detection device.

[0024] In this embodiment, (TiO2) is formed by using a titanium dioxide cluster to graphene mass ratio of 70:30 to 80:20. n The specific structure of the graphene (n=1-4) balances catalytic activity and conductivity, significantly improving the adsorption selectivity and response value of SF6 decomposition components. Furthermore, this sensor has a simple structure and low fabrication cost.

[0025] Furthermore, in this embodiment, the external detection device may be, for example, an electrochemical workstation.

[0026] Furthermore, the interdigitated electrode substrate includes a surface-cleaned metal interdigitated electrode (preferably made of gold or copper). A titanium dioxide cluster-doped graphene sensitive material layer is tightly attached to the surface of the metal interdigitated electrode of the interdigitated electrode substrate, and the electrode leads are fixedly connected to the pins of the interdigitated electrode substrate to form a complete electrical signal conduction path. In addition, the interdigitated electrode substrate may also include printed circuits, etc.

[0027] Preferably, the thickness of the sensitive material layer is 5-10 μm. This thickness of the sensitive material layer can better ensure detection performance.

[0028] Preferably, the mass ratio of titanium dioxide clusters to graphene in the sensitive material is 75:25, which allows the material to maintain the best gas-sensing performance.

[0029] Example 2 like Figure 1 and 2 This embodiment provides a method for preparing a titanium dioxide-modified graphene gas sensor as described in Example 1. The preparation method includes the following steps: S201, Provides interdigitated electrode substrate.

[0030] S202, Preparation of titanium dioxide cluster-doped graphene sensitive materials.

[0031] This step S202 specifically includes the following sub-steps: S2021. Prepare intrinsic graphene powder.

[0032] S2022. Preparation of graphene dispersion: Weigh 10 mg of intrinsic graphene powder, add it to 20 mL of ultrapure water, and ultrasonically disperse for 30 minutes to obtain a uniformly dispersed graphene dispersion.

[0033] S2023. Preparation of Ti(SO4)2 solution: Weigh 0.30g of Ti(SO4)2 solid, dissolve it in 20mL of deionized water, and stir until completely dissolved.

[0034] S2024. Mixing and hydrothermal reaction: Mix the graphene dispersion with Ti(SO4)2 solution and sonicate at room temperature for 12 hours; add 0.6g of urea dissolved in 20mL of deionized water to form a urea solution, stir evenly and transfer to a reaction vessel, and hydrothermally react at 96℃ for 10 hours.

[0035] S2025. Cleaning and Drying: The reaction product was washed three times alternately with deionized water and anhydrous ethanol to remove residual impurities, and then dried at 60°C to obtain titanium dioxide cluster-doped graphene sensitive material; wherein the mass ratio of titanium dioxide clusters to graphene was 75:25, and the titanium dioxide clusters were in the form of (TiO2). n -Graphene (n=1-4) structures are uniformly dispersed on the graphene surface.

[0036] It should be noted that the mass ratio of the prepared titanium dioxide clusters to graphene can be adjusted within the range of 70:30-80:20 while still maintaining good gas-sensing performance, with 75:25 being the optimal ratio.

[0037] Furthermore, the preparation of intrinsic graphene powder in step S2021 specifically includes the following steps: S20211. Preparation of mixed acid: Measure 98% concentrated sulfuric acid and 85% concentrated phosphoric acid in a volume ratio of 9:1, mix them evenly, and place them in a reaction vessel.

[0038] S20212. Constructing the reaction system: Add graphite powder to the mixed acid, stir evenly, and then place the reaction vessel in a constant temperature stirring device at 50±1℃.

[0039] S20213. Adding oxidant: Potassium permanganate is slowly added to the reaction system in a controlled manner, and the system temperature is maintained at 50±1℃ to avoid local overheating.

[0040] S20214. Oxidation and Termination of Reaction: After adding potassium permanganate, continue stirring for 3 hours. Then, slowly add diluted hydrogen peroxide (volume ratio 1:10) until the reaction system turns bright yellow and no bubbles are generated, thus terminating the oxidation reaction.

[0041] S20215. Purification and Drying: The reaction product was diluted and centrifuged and washed until pH≈6, and then dried to obtain intrinsic graphene powder.

[0042] It should be noted that in the preparation of intrinsic graphene powder, the volume ratio of the mixed acid can be finely adjusted within the range of 8:2 to 9.5:0.5, and the reaction temperature can be controlled within 48-52℃; the hydrothermal reaction temperature can be adjusted within the range of 90-100℃, the reaction time can be adjusted within the range of 8-12 hours, and the pH value can be adjusted between 5.5 and 6.5. Stable sensitive materials can be prepared within these ranges.

[0043] In steps S20211 to S20215, by precisely controlling parameters such as the mixed acid ratio, reaction temperature, and hydrothermal conditions, the problem of uneven doping in traditional modification processes can be solved, ensuring the stability of the properties of sensitive materials.

[0044] S203. The metal interdigitated electrodes in the interdigitated electrode substrate are wiped with ethanol, rinsed with deionized water, and dried with nitrogen to remove surface oil and impurities.

[0045] S204. The titanium dioxide cluster-doped graphene sensitive material is mixed with ethanol and ultrasonically dispersed to form a dispersion.

[0046] S205. Heat the metal interdigitated electrode and uniformly coat the dispersion onto the surface of the metal interdigitated electrode, with the coating thickness controlled at 5-10 μm.

[0047] In this step, the heating temperature of the interdigitated metal electrode is preferably 70~90°C, and most preferably 80°C. Heating temperatures within this range facilitate the deposition and adhesion of the dispersion on the interdigitated metal electrode.

[0048] In addition, the dispersion can be coated onto the surface of the interdigitated electrode by spraying, dripping, or spin coating, and the detection performance can be guaranteed by controlling the thickness to 5-10 μm.

[0049] S206. The sprayed interdigitated electrode substrate is placed in an oven for drying to obtain the titanium dioxide modified graphene gas sensor.

[0050] In this step, the oven temperature is preferably 55~65℃, and most preferably 60℃. The drying time is preferably 25~35 minutes, and most preferably 30 minutes.

[0051] Example 3 like Figure 4 This embodiment provides an SF6 decomposition component detection device. The device includes: a titanium dioxide modified graphene gas sensor 4, an electrochemical workstation 1, a dynamic gas mixing instrument 6, a test gas chamber 5, and a data processing module (not shown).

[0052] Among them, the titanium dioxide modified graphene gas sensor 4 can be the gas sensor as in Example 1 of the present invention, which is used to adsorb SF6 decomposition components and convert the concentration change of the decomposition components into a resistance change signal.

[0053] The electrochemical workstation 1 is connected to the gas sensor via electrode leads 2 for real-time monitoring of the resistance change signal. The electrochemical workstation 1 may have a display for displaying the changing resistance value in real time based on the resistance change signal.

[0054] The dynamic gas mixer 6 is used to prepare standard gases of SF6 decomposition components at different concentrations. The dynamic gas mixer 6 can be connected to different gas cylinders, such as H2S, SO2, SOF2, and SO2F2 cylinders. Each gas cylinder may have a cylinder exhaust valve 12 and a cylinder filling port 13, used to supply gas to the dynamic gas mixer 6 and to fill the corresponding gas cylinder, respectively. The dynamic gas mixer 6 is equipped with multiple cylinder inlet valves 11 to introduce gas from the corresponding cylinder into the dynamic gas mixer 6.

[0055] The test gas chamber 5 is used to contain the gas-sensitive sensor 4 and the target detection gas, ensuring the sealing and stability of the detection process. The volume of the test gas chamber is preferably 80-150 mL, and most preferably 100 mL. Both the test gas chamber 5 and the dynamic gas mixer 6 have a gas inlet and a gas outlet. The test gas chamber 5 also has a carrier gas inlet connected to the nitrogen generator 3. The gas inlet of the test gas chamber 5 is connected to the gas outlet of the dynamic gas mixer 6 via a first gas path, and the gas outlet of the test gas chamber 5 is connected to the inlet of the dynamic gas mixer 6 via a second gas path. Both the first and second gas paths are equipped with gas path switches 7, and the second gas path also includes a flow regulating valve 8, a purge exhaust valve 9, and a circulation pump 10. This allows for convenient delivery of the gas mixed by the dynamic gas mixer 6 into the test gas chamber 5 for testing, control of the gas flow rate, and simultaneous nitrogen purging operations.

[0056] The data processing module is used to receive data related to the resistance change signal transmitted by the electrochemical workstation 1, calculate the gas-sensitive response value, and output the detection result.

[0057] In this embodiment, because the sensor has a simple structure and low manufacturing cost, and the matching detection equipment is small in size and easy to operate, it can realize on-site online real-time monitoring and overcome the limitations of traditional detection methods.

[0058] Example 4 This embodiment provides a method for detecting SF6 decomposition components. The method employs the decomposition component detection device described in Embodiment 3 and includes the following steps: S401. Using an electrochemical workstation as the testing equipment, connect the prepared gas sensor; use a dynamic gas mixing instrument to prepare H2S, SO2, SOF2, and SO2F2 gases with different target concentrations in the range of 10-100ppm, with nitrogen as the balance gas, as standard gases for SF6 decomposition components; place the gas sensor in the test gas chamber and keep the gas flow rate constant.

[0059] The preferred gas flow rate is 40-60 mL / min, and the most preferred is 50 mL / min.

[0060] S402. Nitrogen gas is introduced into the test gas chamber. After the resistance change signal of the gas sensor displayed on the electrochemical workstation indicates that the resistance value has stabilized, the stabilized resistance value is recorded as the baseline resistance value R0, and the nitrogen gas is introduced is stopped.

[0061] S403. Select and introduce the standard gas of the SF6 decomposition component at the target concentration to be measured from various standard gases of SF6 decomposition components, record the change of sensor resistance in real time until the resistance value stabilizes, and record the corresponding resistance value R; calculate the gas-sensitive response value according to the preset formula, the preset formula is: gas-sensitive response value = |R-R0| / R0×100%; repeat the test multiple times, and take the average gas-sensitive response value as the detection result.

[0062] The preferred number of repeated tests is 2 to 5, with the most preferred number being 3.

[0063] In addition, the relative standard deviation of repeated tests is preferably less than a preset deviation threshold (e.g., <5%) to ensure the reliability of the test results.

[0064] S404. After the standard gas detection of each concentration of SF6 decomposition components is completed, nitrogen gas is introduced to purge the gas chamber to restore the sensor to the baseline resistance R0.

[0065] The preferred purging time is 25-35 minutes, with the most preferred time being 30 minutes.

[0066] In this embodiment, the detection process is optimized through the above steps, enabling rapid detection of SF6 decomposition components in the concentration range of 10-100ppm at room temperature and pressure, with a response time of ≤30 seconds and a recovery time of ≤1 minute, meeting the timeliness requirements of online monitoring.

[0067] To verify the effectiveness of the present invention, relevant experiments were conducted based on the above embodiments, and the results were obtained. Figures 5-10 ,in: Figure 5 The present invention provides different titanium dioxide clusters ((TiO2)). n -Graphene (n=1, 2, 3 or 4) The total density of states (TDOS) and partial density of states (PDOS) of the graphene-doped sensitive material after adsorbing SF6 gas. Figure 5 In the figure, the parts corresponding to serial numbers (a) to (d) are the total density of states (TDOS) and partial density of states (PDOS) of the sensitive materials containing (TiO2)-Graphene, (TiO2)2-Graphene, (TiO2)3-Graphene, and (TiO2)4-Graphene after adsorbing SF6 gas.

[0068] Figure 6The present invention provides different titanium dioxide clusters ((TiO2)). n -Graphene (n=1, 2, 3 or 4) doped graphene sensitive material after adsorption and decomposition of gas H2S, total density of states (TDOS) and partial density of states (PDOS). Figure 6 In the diagram, the parts corresponding to serial numbers (a1) to (d1) are the total density of states (TDOS) and partial density of states (PDOS) of the sensitive materials containing (TiO2)-Graphene, (TiO2)2-Graphene, (TiO2)3-Graphene, and (TiO2)4-Graphene after adsorbing and decomposing gaseous H2S.

[0069] Figure 7 The present invention provides different titanium dioxide clusters ((TiO2)). n -Graphene (n=1, 2, 3 or 4) doped graphene sensitive material after adsorption and decomposition of gas SO2, total density of states (TDOS) and partial density of states (PDOS). Figure 7 In the diagram, the parts corresponding to serial numbers (a1) to (d1) are the total density of states (TDOS) and partial density of states (PDOS) of the sensitive materials containing (TiO2)-Graphene, (TiO2)2-Graphene, (TiO2)3-Graphene, and (TiO2)4-Graphene after adsorbing and decomposing gaseous SO2.

[0070] Figure 8 This invention provides different titanium dioxide clusters ((TiO2)). n -Graphene, n=1, 2, 3 or 4) The total density of states (TDOS) and partial density of states (PDOS) of the graphene-doped sensitive material after adsorption and decomposition of SOF2 gas. Figure 8 In the diagram, the parts corresponding to serial numbers (a1) to (d1) are the total density of states (TDOS) and partial density of states (PDOS) of the sensitive materials containing (TiO2)-Graphene, (TiO2)2-Graphene, (TiO2)3-Graphene, and (TiO2)4-Graphene after adsorbing and decomposing gas SOF2.

[0071] Figure 9 The present invention provides different titanium dioxide clusters ((TiO2)). n -Graphene, n=1, 2, 3 or 4) The total density of states (TDOS) and partial density of states (PDOS) of the graphene-doped sensitive material after adsorption and decomposition of gases SO2 and F2. Figure 9In the diagram, the parts corresponding to serial numbers (a1) to (d1) are the total density of states (TDOS) and partial density of states (PDOS) of the sensitive materials containing (TiO2)-Graphene, (TiO2)2-Graphene, (TiO2)3-Graphene, and (TiO2)4-Graphene after adsorbing and decomposing the gas SO2F2.

[0072] Figure 10 These are SEM images of sensitive materials with different mass ratios of titanium dioxide clusters and graphene. Figure 10 In the figure, the parts corresponding to serial numbers (a) to (d) are the cases where the mass ratio of titanium dioxide clusters is 25%, 50%, 75%, and 100%, respectively.

[0073] Figures 5-9 The TDOS diagram shows that after modifying the TiO2 clusters, the system still maintains a high density of states at the Fermi level, proving that the microstructure of the present invention effectively preserves the excellent conductivity of graphene without introducing a high impedance barrier.

[0074] Figures 5-9 The PDOS diagram shows that the Ti-3d orbitals of the TiO2 clusters and the molecular orbitals of SF6 decomposition components (such as SOF2) undergo significant hybridization (peak overlap) near the Fermi level, proving that the cluster sites have extremely strong chemisorption and catalytic activity for the target gas, which is the quantum mechanical basis for achieving high-sensitivity detection.

[0075] Figure 10 The superiority of the technical solution of this invention is strongly demonstrated by the intuitive differences in microscopic morphology. Among them, Figure 10 Figure (c) illustrates that with a titanium dioxide cluster content of 75%, the titanium dioxide nanoparticles of the present invention are extremely uniformly and densely dispersed on the surface of the graphene layered substrate, effectively avoiding the common agglomeration problem of nanomaterials, thereby maximizing the gas-sensitive active sites and preserving good electron transport pathways. In contrast, the 100% titanium dioxide clusters in Figure (d) show obvious accumulation and severe agglomeration. This morphological defect significantly reduces the specific surface area of ​​the material and impairs conductivity, which also demonstrates the necessity and superiority of the present invention in precisely controlling the doping ratio.

[0076] The beneficial effects of this invention are that, compared with the prior art, 1. Optimized Sensitive Material Ratio and Structure: A titanium dioxide cluster to graphene mass ratio of 70:30~80:20 is adopted to form a specific (TiO2)n-Graphene (n=1-4) structure. In this specific structure, titanium dioxide exists in the form of extremely small "clusters" rather than large particles, which makes it easier to achieve high dispersion loading on the two-dimensional graphene surface, thus avoiding the problem of uneven doping from the structural root. At the same time, graphene, as a conductive substrate, is responsible for transmitting resistance change signals. Since the titanium dioxide clusters are very small and uniformly dispersed on the graphene surface, they do not form a huge insulating barrier like large particle agglomerates, thus preserving the excellent conductive network of graphene and ensuring that the sensor can sensitively convert chemical signals into resistance signals. Furthermore, the titanium dioxide clusters provide active sites for the specific adsorption of SF6 decomposition components. Uniform dispersion means that, under the same mass ratio, the surface area of ​​titanium dioxide exposed to the gas is maximized, providing more adsorption sites, thereby significantly improving adsorption selectivity and response value.

[0077] 2. Improve the preparation process: By precisely controlling parameters such as the ratio of mixed acid, reaction temperature, and hydrothermal conditions, the problem of uneven doping can be further improved, ensuring the stability of the performance of sensitive materials; 3. Low-cost and miniaturized design: The sensor has a simple structure and low manufacturing cost. The matching detection equipment is small in size and easy to operate, enabling on-site online real-time monitoring and overcoming the limitations of traditional detection methods. 4. High-efficiency detection method design: It enables rapid detection of SF6 decomposition components in the concentration range of 10-100ppm under normal temperature and pressure, with a response time of ≤30 seconds and a recovery time of ≤1 minute, meeting the timeliness requirements of online monitoring; 5. High stability and repeatability: By optimizing the coating process of sensitive materials and the detection process, the relative standard deviation of the sensor in multiple tests is less than the preset deviation threshold (e.g., 5%), ensuring the reliability of the detection results.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A titanium dioxide-modified graphene gas sensor, characterized in that, include Interdigitated electrode substrate; A sensitive material layer, coated on the surface of the interdigitated electrode substrate, includes titanium dioxide cluster-doped graphene sensitive material; In this sensitive material, the mass ratio of titanium dioxide clusters to graphene is 70:30 to 80:20, and the titanium dioxide clusters are in the form of (TiO2). n - Graphene structures are uniformly dispersed on the graphene surface, n=1, 2, 3 or 4, which are used to specifically adsorb SF6 decomposition components and convert the concentration changes of decomposition components into resistance change signals. Electrode leads are connected to the interdigitated electrode substrate for receiving the resistance change signal of the sensitive material layer via the interdigitated electrode substrate and transmitting it to an external detection device.

2. The titanium dioxide-modified graphene gas sensor according to claim 1, characterized in that, The thickness of the sensitive material layer is 5-10 μm.

3. The titanium dioxide-modified graphene gas sensor according to claim 1, characterized in that, The mass ratio of titanium dioxide clusters to graphene in the sensitive material is 75:

25.

4. A method for preparing a titanium dioxide-modified graphene gas sensor as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Provide interdigitated electrode substrate; Preparation of titanium dioxide cluster-doped graphene sensitive materials; The metal interdigitated electrodes in the interdigitated electrode substrate are wiped with ethanol, rinsed with deionized water, and dried with nitrogen to remove surface oil and impurities. The titanium dioxide cluster-doped graphene-sensitive material was mixed with ethanol and ultrasonically dispersed to form a dispersion. The metal interdigitated electrode is heated, and the dispersion is uniformly coated on the surface of the metal interdigitated electrode, with the coating thickness controlled at 5-10 μm. The sprayed interdigitated electrode substrate was placed in an oven for drying to obtain the titanium dioxide modified graphene gas sensor.

5. The preparation method according to claim 4, characterized in that, The preparation of the titanium dioxide cluster-doped graphene sensitive material includes the following steps: Preparation of intrinsic graphene powder; Intrinsic graphene powder was added to ultrapure water and ultrasonically dispersed to obtain a uniformly dispersed graphene dispersion. Ti(SO4)2 solid was dissolved in deionized water and stirred until completely dissolved to obtain a Ti(SO4)2 solution. The graphene dispersion was mixed with the Ti(SO4)2 solution, and after ultrasonic treatment at room temperature, urea solution was added, and after stirring evenly, the mixture was transferred to a reaction vessel for hydrothermal reaction. The reaction product of the hydrothermal reaction was washed repeatedly with deionized water and anhydrous ethanol to remove residual impurities, and then dried to obtain the titanium dioxide cluster-doped graphene sensitive material; wherein the mass ratio of titanium dioxide clusters to graphene is 70:30~80:20, and the titanium dioxide clusters are in the form of (TiO2). n -Graphene structures are uniformly dispersed on the graphene surface, n=1, 2, 3 or 4.

6. The preparation method according to claim 5, characterized in that, The hydrothermal reaction is carried out at a temperature of 90-100℃ for 8-12 hours.

7. The preparation method according to claim 5, characterized in that, The preparation of intrinsic graphene powder includes the following steps: Measure 98% concentrated sulfuric acid and 85% concentrated phosphoric acid in a volume ratio of 8:2 to 9.5:0.5, mix them thoroughly, and place them in a reaction vessel to obtain a mixed acid. Add graphite powder to the mixed acid, stir evenly, and then place the reaction vessel in a constant temperature stirring device at 48-52℃ to construct the reaction system; Potassium permanganate was slowly added to the reaction system in a controlled manner to maintain the temperature of the reaction system at 48-52℃ and avoid local overheating. After adding potassium permanganate, continue stirring the reaction. Then slowly add diluted hydrogen peroxide until the reaction system turns bright yellow and no bubbles are produced, then terminate the oxidation reaction. The reaction product of the oxidation reaction was diluted, centrifuged and washed until the pH was 5.5-6.5, and then dried to obtain intrinsic graphene powder.

8. The preparation method according to claim 4, characterized in that, The step of uniformly coating the dispersion onto the surface of the interdigitated metal electrode includes: The dispersion is coated onto the surface of the interdigitated electrode using spraying, dripping, or spin coating methods.

9. An SF6 decomposition component detection device, comprising: The titanium dioxide modified graphene gas sensor according to any one of claims 1 to 3 is used to adsorb SF6 decomposition components and convert the concentration change of the decomposition components into a resistance change signal. An electrochemical workstation is connected to the gas sensor via electrode leads for real-time monitoring of the resistance change signal. Dynamic gas mixing instrument is used to prepare standard gases of SF6 decomposition components at different concentrations; The test gas chamber is used to house the gas-sensitive sensor and the target detection gas, ensuring the sealing and stability of the detection process; The data processing module is used to receive data related to the resistance change signal transmitted by the electrochemical workstation, calculate the gas-sensitive response value, and output the detection result.

10. A method for detecting SF6 decomposition components, characterized in that, The device for detecting decomposed components as described in claim 9 is employed, and includes the following steps: An electrochemical workstation was used as the testing equipment and connected to the prepared gas sensor. H2S, SO2, SOF2, and SO2F2 gases with different target concentrations in the range of 10-100ppm were prepared using a dynamic gas mixing instrument with nitrogen as the balance gas as the standard gas for SF6 decomposition components. The gas sensor was placed in the test gas chamber and the gas flow rate was kept constant. Nitrogen gas is introduced into the test chamber. After the resistance change signal of the gas sensor displayed on the electrochemical workstation indicates that the resistance value has stabilized, the stabilized resistance value is recorded as the baseline resistance value R0, and the nitrogen gas introduction is stopped. Select and introduce the target concentration of SF6 decomposition component standard gas from various SF6 decomposition component standard gases, record the sensor resistance change in real time until the resistance value stabilizes, and record the corresponding resistance value R. The gas-sensitive response value is calculated according to a preset formula, which is: Gas-sensitive response value = |R - R0| / R0 × 100%; Repeat the test multiple times to ensure that the relative standard deviation of the multiple repeated tests is less than the preset deviation threshold, and take the average gas-sensitive response value of the multiple repeated tests as the detection result; After the standard gas detection of each concentration of SF6 decomposition components is completed, nitrogen gas is introduced into the purging chamber to restore the sensor to the baseline resistance R0.

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