A method for fabricating a nano-modified graphene thin film sensor and its application

Abstract

This invention discloses a method for preparing a nano-modified graphene thin film sensor and its application, relating to the field of transformer fault characteristic gas detection technology. The preparation method involves dissolving AlCl3 in anhydrous ethanol, mixing it with an aqueous solution of graphene oxide, and heating and stirring until Al... 3+ The concentration of the solvent was 0.3-1.5 mol / L to obtain a sol; the sol was mixed with glycerol to obtain a coating solution; the interdigitated Cu / Ni metal electrode was immersed in the coating solution, coated, allowed to stand, heat-treated, washed, and dried to obtain an Al2O3 / GO thin film sensor, which is a nano-modified graphene thin film sensor. The prepared sensor has high sensitivity for detecting acetylene in transformer oil, fast detection response capability, and high temperature resistance.

Description

Technical Field

[0001] This invention relates to the field of transformer fault characteristic gas detection technology, and in particular to a method for preparing a nano-modified graphene thin film sensor and its application. Background Technology

[0002] With the continuous increase in societal demand for electricity, the stability of the power system has become an indispensable part of social development. As one of the most critical devices for voltage conversion in power lines, the operating status of power transformers is crucial to the safe and stable operation of the entire power system. When an internal fault occurs in a transformer, the transformer oil decomposes into H2, C2H2, CH4, etc. The changes in the composition of each gas and the generation rate of each gas are very important indicators for detecting transformer faults. Monitoring acetylene is one of the keys to early fault detection. Therefore, by sensitively detecting the dissolved gas components in transformer oil, the internal fault situation and development trend of the transformer can be effectively understood, thereby scientifically assessing the insulation operating status of the transformer and effectively reducing the incidence of accidents.

[0003] Traditional methods for online detection of fault gases in transformers mainly include gas chromatography, infrared spectroscopy, acoustic spectroscopy, and gas sensors. These methods generally suffer from drawbacks such as expensive equipment, complex operation, relatively low measurement accuracy, susceptibility to interference, and long experimental cycles, making them unsuitable for real-time online monitoring of characteristic gases in transformer faults. With the development of smart grid construction, the scope of damage caused by grid faults is expanding. Ensuring the safe and reliable operation of the grid requires intelligent monitoring of its operational status at all stages, urgently necessitating the development and support of new monitoring technologies. Transformer fault diagnosis methods based on dissolved gas analysis in transformer oil mainly include the traditional three-ratio method; however, the accuracy of fault diagnosis using this method is relatively low. Because the generation mechanism of dissolved gases in transformer oil is complex and involves some uncertainties, it is necessary to rely on experience while utilizing appropriate intelligent models to extract and classify data features. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a nano-modified graphene thin film sensor and its application, so as to solve the problems existing in the prior art. The prepared nano-modified graphene thin film sensor has high sensitivity for detecting acetylene in transformer oil, has a fast detection response capability, and is resistant to high temperature.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] This invention provides a method for preparing a nano-modified graphene thin film sensor, comprising the following steps:

[0007] (1) Dissolve AlCl3 in anhydrous ethanol, mix with an aqueous solution of graphene oxide (GO), and heat and stir until Al... 3+ The concentration was 0.3-1.5 mol / L, resulting in a sol;

[0008] (2) The above sol is mixed with glycerol to obtain a coating solution;

[0009] (3) Immerse the interdigitated Cu / Ni metal electrode into the coating solution, lift and coat the film, let it stand, heat treat, wash and dry to obtain the Al2O3 / GO thin film sensor, which is the nano-modified graphene thin film sensor.

[0010] Preferably, in the method for fabricating the nano-modified graphene thin film sensor, the method for fabricating the interdigitated Cu / Ni metal electrode is as follows: The interdigitated Cu / Ni metal electrode is fabricated on a printed circuit board (PCB) substrate using sputtering, photolithography, and etching processes. The electrode linewidth and gap width are 100-200 μm, and the thickness is 10-25 μm. Within this range, the electrode linewidth and gap width are 120-200 μm. More preferably, the electrode linewidth and gap width are 200 μm, and the thickness is 20 μm.

[0011] Preferably, in the method for preparing the nano-modified graphene thin film sensor, in step (1), the heating and stirring temperature is 50-75℃, and the stirring time is 3-8 hours, preferably 75℃, and the stirring time is 5 hours. 3+ The concentration is 0.3-1.5 mol / L, preferably heated and stirred until Al 3+ The concentration is 0.5 mol / L, and the sol is relatively stable within this concentration range.

[0012] Preferably, in the method for preparing the nano-modified graphene thin film sensor, in step (2), the sol and glycerol are mixed at a volume ratio of 10:1 to 15:1, preferably at a volume ratio of 13:1, and the coating solution is obtained after mixing the sol and glycerol.

[0013] Preferably, in the method for preparing the nano-modified graphene film sensor, the heat treatment temperature in step (3) is 100-120℃ and the heat treatment time is 10-20 minutes, which can improve the stability of the nano-modified graphene film sensor. More preferably, the heat treatment temperature is 120℃ and the heat treatment time is 15 minutes.

[0014] Preferably, the Al2O3 / GO thin film sensor is prepared using the sol-gel static dip-coating (SGDC) method. First, AlCl3 is dissolved in anhydrous ethanol, then mixed with an aqueous solution of graphene oxide. The mixture is heated and stirred at 50-75°C for 3-8 hours, and the solution is evaporated to control the Al content.3+ The concentration of the solvent was 0.3-1.5 mol / L to obtain a sol. The obtained sol and glycerol were mixed uniformly at a volume ratio of 10:1-15:1 to obtain a coating solution. The interdigitated electrode was immersed in the coating solution for 30 seconds, then the substrate was vertically lifted and laid flat. After the wet film was allowed to hydrolyze in air for a period of time, it was heat-treated at 100-120℃ for 10-20 minutes (gelation). The above immersion, lifting, and gelation steps were repeated 5 times. Then, it was washed with deionized water and dried at 120℃ in nitrogen to obtain the Al2O3 / GO thin film sensor.

[0015] Preferably, in the method for preparing the nano-modified graphene thin film sensor, after the drying process in step (3), a sintering step is also included. To ensure complete combustion of the organic matter, the thin film needs to be sintered. During sintering, to prevent cracking, the temperature is increased to 300°C at a rate of 50-70°C / h and held for 15 minutes; then increased to 550°C at the same rate and held for 1-3 hours. More preferably, the heating rate during thin film sintering is 60°C / h, increasing to 550°C, and holding for 2 hours.

[0016] Preferably, in the method for preparing the nano-modified graphene thin film sensor, after sintering, a step of depositing gold nanoparticles is further included.

[0017] Preferably, in the method for preparing the nano-modified graphene thin film sensor, after depositing gold nanoparticles, a heating step is further included to obtain the Au@Al2O3 / rGO thin film sensor.

[0018] The nano-modified graphene thin film sensor of this invention is often used as a gas sensor. In order to enhance the sensitivity of the gas sensor, a layer of active gold nanoparticles is deposited on the surface of the film by an impregnation method (existing conventional technology can be used, which will not be described in detail here). Then, the sensor is placed in a heating chamber and heated at a high temperature of 100-300℃ for 2-5 hours to thermally reduce GO, so as to obtain the Au@Al2O3 / rGO thin film sensor.

[0019] Preferably, in the method for preparing the nano-modified graphene thin film sensor, the loading of active gold nanoparticles is 0.3 wt% (relative to the mass of the Al2O3 / GO thin film sensor).

[0020] Preferably, the active gold nanoparticles are prepared by laser ablation (the specific preparation method is a conventional technique in the field), and the particle size is 5 nm.

[0021] Preferably, in the method for preparing the nano-modified graphene thin film sensor, the heating temperature is 100-300℃ and the heating time is 1-3 hours. At this heating temperature, GO undergoes a thermal reduction reaction, and the sensor with deposited gold nanoparticles can be transformed into an Au@Al2O3 / rGO thin film sensor after this reaction. More preferably, the reduction temperature of GO is 200℃ and the reduction time is 4 hours.

[0022] Preferably, in the method for preparing the nano-modified graphene thin film sensor, after heating, the method further includes a step of depositing an ionic liquid on the surface of the Au@Al2O3 / rGO thin film sensor. To broaden the detection temperature range of the thin film sensor and maintain stability under high-temperature detection, an ionic liquid layer is carbonized on the film surface at high temperature. This is achieved by high-temperature calcination under a nitrogen atmosphere to carbonize the ionic liquid onto the surface of the thin film sensor, thus obtaining the IL@Au@Al2O3 / rGO thin film sensor.

[0023] Preferably, the ionic liquid is at least one selected from the compounds of formulas (I) to (IV) that exist in a molten state;

[0024]

[0025] In formula (I),

[0026] R1, R2, and R3 are each independently defined as C. m H 2m+1 Or phenyl, where m is an integer and 0 ≤ m ≤ 14;

[0027] X1 - It consists of chloride ions, bromide ions, hexafluorophosphate, tetrafluorophosphate, bis(trifluoromethanesulfonyl)imide, tetrafluoroborate or imide, trifluoromethanesulfonate or p-toluenesulfonate.

[0028]

[0029] In formula (II),

[0030] R4, R5, R6, and R7 are each independently classified as C. m H 2m+1 Or phenyl, where m is an integer and 0≤m≤6;

[0031] X2 - It consists of chloride ions, bromide ions, hexafluorophosphate, tetrafluorophosphate, bis(trifluoromethanesulfonyl)imide, tetrafluoroborate or imide, trifluoromethanesulfonate or p-toluenesulfonate.

[0032]

[0033] In formula (III),

[0034] R8, R9, R 10 R 11 Each is independent as C m H 2m+1 Or phenyl, where m is an integer and 0≤m≤6;

[0035] X3 - It consists of chloride ions, bromide ions, hexafluorophosphate, tetrafluorophosphate, bis(trifluoromethanesulfonyl)imide, tetrafluoroborate or imide, trifluoromethanesulfonate or p-toluenesulfonate.

[0036]

[0037] In equation (IV),

[0038] R 12 R 13 R 14 Each is independent as C m H 2m+1 Or phenyl, where m is an integer and 0≤m≤6;

[0039] X4 - Ionic liquids with the following structures—chloride, bromide, hexafluorophosphate, tetrafluorophosphate, trifluoromethanesulfonylimide, tetrafluoroborate or imide, trifluoromethanesulfonate or p-toluenesulfonate—exhibit high stability and high sensitivity at high temperatures.

[0040] Preferably, the loading of the ionic liquid is 5-15 wt%, more preferably 10 wt% (relative to the mass of the Au@Al2O3 / rGO thin film sensor).

[0041] Preferably, the high-temperature calcination temperature of the ionic liquid is 400-800℃, more preferably 600℃. The heating rate is 10℃ / min, and the holding time is 3h.

[0042] Alumina, as a third-generation semiconductor material, is also known as a wide-bandgap semiconductor material due to its bandgap width greater than or equal to 2.3 eV. Compared to the previous two generations, it offers significant performance advantages. With its high efficiency, high density, and high reliability, it can operate in high-frequency, high-power, and high-temperature environments, making it a highly promising nanomaterial for nanosensing. Furthermore, metal doping of the nanomaterial surface can effectively enhance the adsorption and sensing performance of the adsorption system for gas molecules, significantly improving the detection sensitivity of the nanosensor. Gold, in particular, exhibits excellent gas-sensitive catalytic activity and a strong adsorption effect on acetylene gas, thus improving gas detection performance. It demonstrates high detection sensitivity for low volume fractions of acetylene, enabling high-performance detection of dissolved acetylene content in transformer oil. To provide a miniaturized, high-performance, and low-cost gas-sensitive sensing element, and a new method for detecting characteristic gases in transformer faults, this invention introduces graphene into the gas-sensitive sensing element for gas molecule detection. It has been demonstrated that the charge carrier density of graphene changes with the adsorption or desorption of surface gas molecules. Ionic liquids, also known as room-temperature molten salts, are composed entirely of anions and cations. They possess advantages such as high conductivity, low melting point, near-non-volatile nature, non-flammability, and high thermal stability. Upon high-temperature carbonization, they form a carbon film, which provides excellent protection for the encapsulated material. When applied to nano-modified graphene thin-film sensors, this improves sensor stability and expands the detection temperature range, maintaining stability under high-temperature detection, exhibiting high sensitivity, and rapid response capabilities. In summary, nano-modified graphene thin-film sensors can improve the sensitivity of acetylene gas detection in transformer oil and expand the detection temperature range. This is of great significance for enabling rapid and sensitive detection of transformer insulation fault types and severity, providing a basis for decision-making.

[0043] Application of a nano-modified graphene thin film sensor prepared according to the preparation method in transformer fault early warning.

[0044] Application of a nano-modified graphene thin film sensor prepared according to the preparation method in acetylene detection.

[0045] The present invention discloses the following technical effects:

[0046] (1) The nano-modified graphene film sensor has good sensitivity to acetylene gas at a lower operating temperature and has fast response-recovery characteristics.

[0047] (2) Loading of active gold nanoparticles greatly enhances the sensitivity of the gas sensor due to the good adsorption of acetylene by gold.

[0048] (3) A layer of ionic liquid is carbonized on the surface of the Au@Al2O3 / rGO thin film sensor at high temperature, so that even under high temperature detection, the acetylene gas molecules adsorbed on the material surface are not easy to detach, thus making the thin film sensor exhibit high sensitivity in high temperature detection. Detailed Implementation

[0049] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0050] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0051] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0052] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0053] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0054] The room temperature in this invention refers to 25±2℃.

[0055] Example 1

[0056] (1) Fabrication of IL@Au@Al2O3 / rGO thin film sensor

[0057] First, interdigitated Cu / Ni metal electrodes (i.e., interdigitated electrodes) were fabricated on a printed circuit board (PCB) substrate using sputtering, photolithography, and etching processes. Specifically, in a pure argon atmosphere (0.7 Pa), a titanium disk (76 mm in diameter) was used as the main cathode material for the magnetron (rated power 150 W). Two targets, one nickel and one copper, were mounted on the cathode of the discharge system. The interdigitated Cu / Ni metal electrodes were fabricated using unbalanced magnetron co-sputtering technology. Then, using the sol-gel static dip-coating (SGDC) method, 2 g of AlCl3 was dissolved in 30 mL of anhydrous ethanol, and 1 g of graphene oxide was dissolved in 20 mL of deionized water. The solutions were mixed (i.e., the anhydrous ethanol containing AlCl3 was mixed with the deionized water containing graphene oxide), heated and stirred to 75°C for 5 hours, and the solution was evaporated to control the Al content. 3+ The concentration of the solvent was 0.5 mol / L to obtain a sol. The obtained sol and glycerol were mixed evenly at a volume ratio of 13:1 to obtain a coating solution. The interdigitated electrode was immersed in the coating solution for 30 seconds, and then the substrate (printed circuit board substrate) was vertically lifted and laid flat. After the wet film was hydrolyzed in air for 5 minutes, it was heat-treated at 120°C for 15 minutes (gelation). The above immersion, lifting, and gelation steps were repeated 5 times. Then, it was washed with deionized water and dried at 120°C in nitrogen. Then, the film was sintered by heating to 300°C at a heating rate of 60°C / h and holding for 15 minutes; then, it was heated to 550°C at the same rate and held for 2 hours to obtain an Al2O3 / GO thin film sensor. An active gold nanoparticle layer was deposited on the surface of the Al2O3 / GO thin film sensor by dip-coating, and the loading of the active gold nanoparticles was 0.3 wt% (relative to the mass of the Al2O3 / GO thin film sensor). The sensor was then placed in a heating chamber and heated at 200°C for 4 hours to thermally reduce GO, yielding the Au@Al2O3 / rGO thin-film sensor. A layer of 1-methyl-butylimidazolium chloride ionic liquid was then carbonized on the thin film surface at high temperature and calcined at 600°C for 3 hours under a nitrogen atmosphere. With an ionic liquid loading of 10 wt% (relative to the mass of the Au@Al2O3 / rGO thin-film sensor), the IL@Au@Al2O3 / rGO thin-film sensor was obtained.

[0058] (2) Testing of IL@Au@Al2O3 / rGO thin film sensor

[0059] The sensor's operating temperature is achieved by applying different voltages to a regulated power supply for heating. The resistance response of the thin-film sensor under different gas environments is tested by injecting different volume fractions of gas into a sealed gas chamber. This is to study the gas-sensing characteristics of a specific sensitive thin-film sensor corresponding to a particular gas.

[0060] The aforementioned thin-film sensor was placed in an acetylene gas volume fraction of 150 × 10⁻⁶. -6 Under the specified conditions, the sensitivity of the IL@Au@Al2O3 / rGO sensor at 70℃ was 27.23%; the sensitivity of the Al2O3 / GO thin film sensor at 70℃ was 8.47%; and the sensitivity of the Au@Al2O3 / rGO thin film sensor at 70℃ was 11.53%.

[0061] The IL@Au@Al2O3 / rGO sensor has a sensitivity of 27.23% at 80℃; the Al2O3 / GO thin film sensor has a sensitivity of 9.71% at 80℃; and the Au@Al2O3 / rGO thin film sensor has a sensitivity of 13.62% at 80℃.

[0062] The IL@Au@Al2O3 / rGO sensor has a sensitivity of 27.23% at 100℃; the Al2O3 / GO thin film sensor has a sensitivity of 9.43% at 100℃; and the Au@Al2O3 / rGO thin film sensor has a sensitivity of 10.82% at 100℃.

[0063] The IL@Au@Al2O3 / rGO sensor has a sensitivity of 27.23% at 140℃; the Al2O3 / GO thin film sensor has a sensitivity of 6.49% at 140℃; and the Au@Al2O3 / rGO thin film sensor has a sensitivity of 8.23% at 140℃.

[0064] The above demonstrates that gold has excellent gas-sensitive catalytic properties and a strong adsorption effect on acetylene gas, which can improve gas detection performance and provide high detection sensitivity for acetylene with low gas volume fractions. The charge carrier density of graphene changes with the adsorption or desorption of surface gas molecules. Introducing ionic liquids can improve the stability of the sensor, expand the detection temperature range, maintain stability under high-temperature detection, and provide high sensitivity and rapid response.

[0065] Example 2

[0066] (1) The preparation method of the IL@Au@Al2O3 / rGO thin film sensor is the same as that in Example 1, except that the ionic liquid is 1-methyl-butyl-hexafluorophosphate.

[0067] (2) Testing of IL@Au@Al2O3 / rGO thin film sensor

[0068] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1. The above-mentioned IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 150 × 10⁻⁶. -6 In this environment, the sensitivity of the sensor at 80℃ was 28.26%.

[0069] Example 3

[0070] (1) The preparation method of the IL@Au@Al2O3 / rGO thin film sensor is the same as that in Example 1, except that the ionic liquid is 1-methyl-hexyl-imidazolium nitrate.

[0071] (2) Testing of IL@Au@Al2O3 / rGO thin film sensor

[0072] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1. The above-mentioned IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 150 × 10⁻⁶. -6 Under certain conditions, the sensitivity of the sensor at 90℃ was 29.33%.

[0073] Example 4

[0074] (1) The preparation method of the IL@Au@Al2O3 / rGO thin film sensor is the same as that in Example 1, except that the ionic liquid is 1-methyl-3-octyl ether imidazole hexafluorophosphate.

[0075] (2) Testing of IL@Au@Al2O3 / rGO thin film sensor

[0076] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1. The above-mentioned IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 150 × 10⁻⁶. -6 In this environment, the sensitivity of the sensor at 100℃ was 31.24%.

[0077] Example 5

[0078] (1) The preparation method of the IL@Au@Al2O3 / rGO thin film sensor is the same as that in Example 1, except that the ionic liquid is N-butyl ether-N-methylpyrrolidone bis(trifluoromethanesulfonyl)imide salt.

[0079] (2) Testing of IL@Au@Al2O3 / rGO thin film sensor

[0080] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1. The above-mentioned IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 150 × 10⁻⁶. -6 In this environment, the sensitivity of the sensor at 110℃ was 33.56%.

[0081] Example 6

[0082] (1) The preparation method of the IL@Au@Al2O3 / rGO thin film sensor is the same as that in Example 1, except that the ionic liquid is 1-butyl-3-methyl ether imidazole tetrafluoroborate.

[0083] (2) Testing of IL@Au@Al2O3 / rGO thin film sensor

[0084] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1. The above-mentioned IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 150 × 10⁻⁶. -6 In this environment, the sensor's sensitivity at 120℃ was 31.49%.

[0085] Example 7

[0086] (1) The preparation method of the IL@Au@Al2O3 / rGO thin film sensor is the same as that in Example 1, except that the ionic liquid is 1-methyl-hexadecylimidazolium bromide.

[0087] (2) Testing of IL@Au@Al2O3 / rGO thin film sensor

[0088] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1. The above-mentioned IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 150 × 10⁻⁶. -6 In this environment, the sensitivity of the sensor at 130℃ was 29.81%.

[0089] Example 8

[0090] (1) The preparation method of the IL@Au@Al2O3 / rGO thin film sensor is the same as that in Example 1, except that the ionic liquid is 1-methyl-3-hydroxyethylimidazolium nitrate.

[0091] (2) Testing of IL@Au@Al2O3 / rGO thin film sensor

[0092] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1. The above-mentioned IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 150 × 10⁻⁶. -6 In this environment, the sensitivity of the sensor was 28.17% at 140℃.

[0093] Example 9

[0094] (1) The preparation method of the IL@Au@Al2O3 / rGO thin film sensor is the same as that in Example 1, except that the ionic liquid is 1-methyl-butyl-hexafluorophosphate.

[0095] (2) Testing of IL@Au@Al2O3 / rGO thin film sensor

[0096] The gas-sensing characteristic detection method of the thin-film sensor for the corresponding gas is the same as in Example 1. The above-mentioned thin-film sensor is placed in an environment with acetylene gas volume fraction of 50 × 10⁻⁶. -6 In this environment, the sensitivity of the sensor at 110℃ was 24.23%.

[0097] Example 10

[0098] (1) The preparation method of the IL@Au@Al2O3 / rGO thin film sensor is the same as that in Example 1, except that the ionic liquid is replaced with 1-butyl-3-methyl ether imidazole tetrafluoroborate.

[0099] (2) Testing of IL@Au@Al2O3 / rGO thin film sensor

[0100] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1. The above-mentioned IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 500 × 10⁻⁶. -6 In this environment, the sensitivity of the sensor at 110℃ was 38.78%.

[0101] Example 11

[0102] Same as Example 1, except that the ionic liquid is replaced with 1-pentyl-3-methylimidazolium tetrafluorophosphate.

[0103] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1. The above-mentioned IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 500 × 10⁻⁶. -6 Under the specified conditions, the sensor's sensitivity was 34.57% at 80℃, 30.14% at 120℃, and 26.43% at 140℃.

[0104] Example 12

[0105] Same as Example 1, except that the ionic liquid is replaced with 1-methyl-3-octyl ether imidazole tetrafluorophosphate.

[0106] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1. The above-mentioned IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 500 × 10⁻⁶. -6 Under the specified conditions, the sensor's sensitivity was 28.43% at 80℃, 24.71% at 120℃, and 21.59% at 140℃.

[0107] Example 13

[0108] Same as Example 1, except that the ionic liquid is replaced with 1-octyl-3-methylimidazolium nitrate.

[0109] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1. The above-mentioned IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 500 × 10⁻⁶. -6 Under the specified conditions, the sensor's sensitivity was 33.72% at 80℃, 29.47% at 120℃, and 25.34% at 140℃.

[0110] Example 14

[0111] Same as Example 1, except that the ionic liquid is replaced with 1-butyl-3-methylimidazolium hexafluorophosphate.

[0112] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1. The above-mentioned IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 500 × 10⁻⁶. -6 Under the specified conditions, the sensor's sensitivity was 29.59% at 80℃, 24.16% at 120℃, and 20.57% at 140℃.

[0113] Example 15

[0114] Same as Example 1, except that the ionic liquid is replaced with 1-hexadecyl-3-methylimidazolium chloride.

[0115] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1. The above-mentioned IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 500 × 10⁻⁶. -6 Under the specified conditions, the sensor's sensitivity was 30.54% at 80℃, 26.83% at 120℃, and 24.17% at 140℃.

[0116] Example 16

[0117] Same as Example 1, except that the ionic liquid is replaced with 1-dodecyl-3-methylimidazolium tetrafluorophosphate.

[0118] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1. The above-mentioned IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 500 × 10⁻⁶. -6 Under the specified conditions, the sensor's sensitivity was 31.75% at 80℃, 26.57% at 120℃, and 25.38% at 140℃.

[0119] Example 17

[0120] Same as Example 1, except that the ionic liquid is replaced with 1-propyl-3-methylimidazolium (trifluoromethanesulfonyl) amide salt, with a loading of 12 wt%.

[0121] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1. The above-mentioned IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 500 × 10⁻⁶. -6 Under the specified conditions, the sensor's sensitivity was 32.28% at 80℃, 30.47% at 120℃, and 27.65% at 140℃.

[0122] Example 18

[0123] Same as Example 1, except that the ionic liquid is replaced with 1-ethyl-3-methylimidazolium p-toluenesulfonate, with a loading of 15 wt%.

[0124] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1. The above-mentioned IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 500 × 10⁻⁶. -6 Under the specified conditions, the sensor's sensitivity was 25.49% at 80℃, 21.53% at 120℃, and 19.49% at 140℃.

[0125] Example 19

[0126] Same as Example 1, except that the ionic liquid is replaced with 1-decyl-2,3-dimethylimidazolium nitrate.

[0127] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1. The above-mentioned IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 500 × 10⁻⁶. -6 Under the specified conditions, the sensor's sensitivity was 28.45% at 80℃, 19.51% at 120℃, and 17.46% at 140℃.

[0128] Example 20

[0129] Same as Example 1, except that the ionic liquid is replaced with 1-butyl-2,3-imidazolium p-methylbenzenesulfonate, with a loading of 5 wt%.

[0130] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1. The above-mentioned IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 500 × 10⁻⁶.-6 Under the specified conditions, the sensor's sensitivity was 27.49% at 80℃, 24.58% at 120℃, and 19.73% at 140℃.

[0131] Example 21

[0132] Same as Example 1, except that:

[0133] Dissolve 2g of AlCl3 in 30mL of anhydrous ethanol, and dissolve 1g of graphene oxide in 20mL of deionized water. Mix the solutions, heat and stir to 50℃ for 8 hours, and then evaporate the solution to control the Al content. 3+ The concentration of the solvent was 1.5 mol / L to obtain a sol. The obtained sol and glycerol were mixed uniformly at a volume ratio of 10:1 to obtain a coating solution. The interdigitated electrode was immersed in the coating solution for 30 seconds, then the substrate was vertically lifted and laid flat. After the wet film was hydrolyzed in air for 5 minutes, it was heat-treated at 100°C for 20 minutes (gelation). The above immersion, lifting, and gelation steps were repeated 5 times. Then, it was washed with deionized water and dried at 120°C in nitrogen. The film was then sintered by heating to 300°C at a rate of 50°C / h and holding for 15 minutes; then, it was heated to 550°C at the same rate and held for 3 hours. A layer of active gold nanoparticles was deposited on the film surface using an impregnation method, with an active gold nanoparticle loading of 0.3 wt% (relative to the mass of the Al2O3 / GO thin film sensor). The sensor was then placed in a heating chamber and heated at 300°C for 2 hours to thermally reduce GO, yielding the Au@Al2O3 / rGO thin-film sensor. A layer of 1-methyl-butylimidazolium chloride ionic liquid was then carbonized at high temperature on the thin film surface and calcined at 800°C for 3 hours under a nitrogen atmosphere. The ionic liquid loading was 5 wt% (relative to the mass of the Au@Al2O3 / rGO thin-film sensor), resulting in the IL@Au@Al2O3 / rGO thin-film sensor.

[0134] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1.

[0135] The IL@Au@Al2O3 / rGO sensor has a sensitivity of 21.57% at 70℃, 23.43% at 80℃, 20.64% at 100℃, and 18.72% at 140℃.

[0136] Example 22

[0137] Same as Example 1, except that:

[0138] Dissolve 2g of AlCl3 in 30mL of anhydrous ethanol, and dissolve 1g of graphene oxide in 30mL of deionized water. Mix the solutions, heat and stir to 75°C for 3 hours, and then evaporate the solution to control the Al content. 3+ The concentration of the solvent was 0.3 mol / L to obtain a sol. The obtained sol and glycerol were mixed evenly at a volume ratio of 15:1 to obtain a coating solution. The interdigitated electrode was immersed in the coating solution for 30 seconds, then the substrate was vertically lifted and laid flat. After the wet film was hydrolyzed in air for 5 minutes, it was heat-treated at 120°C for 10 minutes (gelation). The above immersion, lifting, and gelation steps were repeated 5 times. Then, it was washed with deionized water and dried at 120°C in nitrogen. The film was then sintered by heating to 300°C at a rate of 70°C / h and holding for 15 minutes; then, it was heated to 550°C at the same rate and held for 1 hour. A layer of active gold nanoparticles was deposited on the surface of the film by dip-coating, with an active gold nanoparticle loading of 0.3 wt% (relative to the mass of the Al2O3 / GO thin film sensor). The sensor was then placed in a heating chamber and heated at 100°C for 3 hours to thermally reduce GO, yielding the Au@Al2O3 / rGO thin-film sensor. A layer of 1-methyl-butylimidazolium chloride ionic liquid was then carbonized at high temperature on the thin film surface and calcined at 400°C for 3 hours under a nitrogen atmosphere. The ionic liquid loading was 15 wt% (relative to the mass of the Au@Al2O3 / rGO thin-film sensor), resulting in the IL@Au@Al2O3 / rGO thin-film sensor.

[0139] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1.

[0140] The IL@Au@Al2O3 / rGO sensor has a sensitivity of 19.53% at 70℃, 21.71% at 80℃, 20.42% at 100℃, and 16.37% at 140℃.

[0141] Example 23

[0142] Same as Example 1, except that the electrode linewidth and gap width are 100 μm and the thickness is 25 μm when the interdigitated Cu / Ni metal electrode is prepared.

[0143] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1.

[0144] The IL@Au@Al2O3 / rGO sensor has a sensitivity of 16.59% at 70℃, 18.43% at 80℃, 15.67% at 100℃, and 13.29% at 140℃.

[0145] Example 24

[0146] Same as Example 1, except that the electrode linewidth and gap width are 150 μm and the thickness is 10 μm when the interdigitated Cu / Ni metal electrode is prepared.

[0147] The gas-sensing characteristics detection method for the corresponding gas of the thin-film sensor is the same as in Example 1.

[0148] The IL@Au@Al2O3 / rGO sensor has a sensitivity of 22.46% at 70℃, 24.76% at 80℃, 20.51% at 100℃, and 17.69% at 140℃.

[0149] Comparative Example 1

[0150] (1) The preparation process of the IL@Fe@Al2O3 / rGO thin film sensor is the same as in Example 1, except that the active gold nanoparticles are replaced with an equal amount of metallic iron (5nm).

[0151] (2) Testing of IL@Fe@Al2O3 / rGO thin film sensor

[0152] The gas-sensing characteristic detection method of the thin-film sensor for the corresponding gas is the same as in Example 1. The above-mentioned thin-film sensor is placed in an environment with acetylene gas volume fraction of 150 × 10⁻⁶. -6 In the tested environment, the sensor's sensitivity at 70°C was 11.78%. Comparison of Comparative Example 1 and Example 1 shows that active gold nanoparticles exhibit higher chemical stability and superior sensing performance compared to iron nanoparticles. This indicates that active gold nanoparticles demonstrate superior performance in acetylene gas detection sensitivity when applied to thin-film sensors.

[0153] Comparative Example 2

[0154] (1) The preparation method of the IL@Al@Al2O3 / rGO thin film sensor is the same as that in Example 2, except that the active gold nanoparticles are replaced with an equal amount of metallic aluminum (15nm).

[0155] (2) Testing of IL@Al@Al2O3 / rGO thin film sensor

[0156] The gas-sensing characteristic detection method of the thin-film sensor for the corresponding gas is the same as in Example 1. The above-mentioned thin-film sensor is placed in an environment with acetylene gas volume fraction of 150 × 10⁻⁶. -6Under suitable conditions, the sensor's sensitivity at 80°C was 13.78%. Comparison of Comparative Example 2 and Example 2 shows that the active gold nanoparticles exhibit higher gas-sensing catalytic activity and higher surface activity compared to the aluminum nanoparticles. This indicates that the active gold nanoparticles demonstrate superior performance in acetylene gas detection sensitivity when applied to thin-film sensors.

[0157] Comparative Example 3

[0158] (1) The preparation method of the IL@Zn@Al2O3 / rGO thin film sensor is the same as that in Example 3, except that the active gold nanoparticles are replaced with an equal amount of metallic zinc (15nm).

[0159] (2) Testing of IL@Zn@Al2O3 / rGO thin film sensor

[0160] The gas-sensing characteristic detection method of the thin-film sensor for the corresponding gas is the same as in Example 1. The above-mentioned O thin-film sensor is placed in an environment with acetylene gas volume fraction of 150 × 10⁻⁶. -6 In the tested environment, the sensor's sensitivity at 90°C was 14.83%. Comparison of Comparative Example 3 and Example 3 shows that the active gold nanoparticles exhibit higher selectivity and sensitivity compared to the zinc nanoparticles. This indicates that the active gold nanoparticles demonstrate superior performance in acetylene gas detection sensitivity when applied to thin-film sensors.

[0161] Comparative Example 4

[0162] The gas-sensing characteristics of the thin-film sensor prepared in this comparative example are the same as those in Example 1. The difference is that the ionic liquid is replaced with dihydrogen phosphate. The above IL@Au@Al2O3 / rGO thin-film sensor is placed in an environment with acetylene gas volume fraction of 150 × 10⁻⁶. -6 Under suitable conditions, the sensor's sensitivity was 13.53% at 70°C and 10.41% at 140°C. Comparison of Comparative Example 4 and Example 1 shows that the ionic liquid of this invention can improve the detection sensitivity of acetylene gas in transformer oil and expand the detection temperature range, which is of great significance for providing a basis for decision-making in quickly and sensitively detecting the type and severity of transformer insulation faults. This demonstrates that the ionic liquid of this invention exhibits superior performance in terms of acetylene gas detection sensitivity.

[0163] Comparative Example 5

[0164] Same as Example 1, except that after washing with deionized water and drying in nitrogen at 120°C, the film was not sintered.

[0165] The thin-film sensor prepared in this comparative example was placed in an acetylene gas atmosphere with a volume fraction of 150 × 10⁻⁶.-6 Under suitable conditions, the sensitivity of the IL@Au@Al2O3 / rGO sensor at 70°C was 12.51%. Comparison of Comparative Example 5 and Example 1 shows that sintering treatment can prevent film cracking and improve sensitivity. This indicates that sintering the film results in superior performance in terms of acetylene gas detection sensitivity.

[0166] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. The application of a nano-modified graphene thin film sensor in the detection of acetylene in transformer oil, characterized in that, The method for preparing the nano-modified graphene thin film sensor includes the following steps: (1) Dissolve AlCl3 in anhydrous ethanol, mix with an aqueous solution of graphene oxide, and heat and stir until Al... 3+ The concentration was 0.3-1.5 mol / L, resulting in a sol; (2) The above sol is mixed with glycerol to obtain a coating solution; (3) Immerse the interdigitated Cu / Ni metal electrode in the coating solution, lift and coat the film, let it stand, heat treat, wash and dry to obtain an Al2O3 / GO thin film sensor. After drying in step (3), a sintering step is also included; After sintering, the process also includes the deposition of gold nanoparticles; After depositing gold nanoparticles, a heating step is also included to obtain the Au@Al2O3 / rGO thin film sensor; After heating, the process also includes a step of depositing an ionic liquid on the surface of the Au@Al2O3 / rGO thin film sensor, where an ionic liquid layer is carbonized at high temperature on the thin film surface to obtain a nano-modified graphene thin film sensor.

2. The application according to claim 1, characterized in that, The method for preparing the interdigitated Cu / Ni metal electrode is as follows: the interdigitated Cu / Ni metal electrode is prepared on a printed circuit board substrate by sputtering, photolithography and etching processes, the electrode linewidth and gap width are 100-200μm, and the thickness is 10-25μm.

3. The application according to claim 1, characterized in that, In step (3), the heat treatment temperature is 100-120℃ and the heat treatment time is 10-20 minutes.

4. The application according to claim 1, characterized in that, The heating temperature is 100-300℃, and the heating time is 1-3 hours.

5. The application of a nano-modified graphene thin film sensor in transformer fault early warning, characterized in that, The nano-modified graphene film sensor is the nano-modified graphene film sensor of claim 1.

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