Preparation method of Pt / PtO2 / SnO2 ternary heterostructure sensitive material

Abstract

The invention discloses a preparation method of a Pt / PtO2 / SnO2 ternary heterostructure sensitive material, belongs to the technical field of gas sensors, and is suitable for monitoring gas production of a lithium battery. According to the technical scheme, the preparation method comprises the following steps: pretreating SnO2 nanoparticles, mixing the pretreated SnO2 nanoparticles with PtO2 in proportion, grinding to obtain a composite material, and sintering to reduce part of PtO2 into Pt to form a ternary heterostructure sensitive material; and coating an aluminum oxide ceramic tube with a gold electrode with the slurry, sintering, welding a base, inserting a heating wire and aging to construct the sensor. The material is rich in active sites, the sensor is high in ethylene sensitivity, good in selectivity and stable, lithium battery gas production can be accurately monitored, lithium battery thermal runaway early warning is achieved, and a support is provided for battery safety and energy storage risk control.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of gas sensors, in particular to a preparation method of a Pt / PtO2 / SnO2 ternary heterostructure sensitive material. BACKGROUND

[0002] Ethylene (C2H4) as a marker gas in the gas production system of a lithium ion battery is mainly derived from the irreversible decomposition of a solid electrolyte interface (SEI) film of the lithium ion battery and a reduction reaction of a lithiated graphite negative electrode directly exposed to an electrolyte with ethylene carbonate (EC), ethylene gas as a marker gas of abnormal decomposition of the electrolyte on the negative electrode side will show a clear change trend in the very early stage of thermal runaway, and accounts for about 8% in the total gas production amount of the lithium ion battery in the whole life cycle, therefore, ethylene gas can be used as an important target gas for early safety monitoring of the battery.

[0003] The semiconductor type ethylene sensor has the advantages of simple preparation process and low cost, and is of great significance for monitoring ethylene gas released in the early stage of thermal runaway of the lithium battery. However, the traditional semiconductor ethylene sensor has the disadvantages of high working temperature (usually > 250 DEG C), large power consumption, long response recovery time, poor stability and being easily disturbed by environmental temperature and humidity. Therefore, it is urgent to develop an ethylene sensor with fast response and low power consumption to realize accurate early warning of thermal runaway of the lithium battery.

[0004] Therefore, development of an ethylene gas sensing material and device with high sensitivity, fast response and complex environment anti-interference ability can significantly improve the early warning ability of thermal runaway, and provide key data support for prolonging the cycle life of the battery and optimizing the risk control strategy of the energy storage system, and has important significance for building a whole life cycle battery safety guarantee system. The ternary heterojunction further improves the electron mobility by regulating the energy band structure of the interface, reduces the reaction energy barrier of the catalytic layer, and significantly enhances the response sensitivity to ethylene gas, thereby providing key technical support for early warning of thermal runaway of the lithium battery. SUMMARY

[0005] The purpose of the application is to detect ethylene gas produced in the lithium ion battery more quickly and accurately, and to provide a preparation method of a Pt / PtO2 / SnO2 ternary heterostructure sensitive material.

[0006] The purpose of the application is achieved by the following technical solutions:

[0007] A preparation method of a Pt / PtO2 / SnO2 ternary heterostructure sensitive material is provided, and the sensitive material prepared by the method is composed of a ternary heterostructure of a SnO2 nanoparticle base material and Pt and PtO2 nanoparticles.

[0008] Further, the sum of the atomic ratio of Pt and PtO2 in the sensitive material is 3%, and the molar ratio of Pt nanoparticles to PtO2 is 1:2; wherein the molecular percentage of Pt nanoparticles in the sensitive material is 2%, and the molecular percentage of PtO2 in the sensitive material is 1%.

[0009] Further, the particle size of each component in the sensitive material satisfies: the particle size of the SnO2 nanoparticle matrix is 20-50 nm; the particle size of the Pt nanoparticle is 10-30 nm; and the particle size of the PtO2 nanoparticle is 5-30 nm.

[0010] Further, the method comprises a pretreatment step of the SnO2 nanoparticle matrix: dispersing the nanometer tin dioxide raw material in a mixed solution of water and ethanol, centrifuging and drying after ultrasonic crushing to obtain the SnO2 powder before pretreatment; and sintering the SnO2 powder at 300-600°C, with a sintering heating rate of 5°C / min and a sintering time of 1-5 h to obtain the pretreated SnO2 powder.

[0011] Further, the method comprises a preparation step of the PtO2 / SnO2 composite material: taking the pretreated SnO2 powder in claim 4, mixing with PtO2 at an atomic ratio of 1-7% in a mortar, and grinding to obtain the PtO2 / SnO2 composite material.

[0012] Further, the method comprises a preparation step of the Pt / PtO2 / SnO2 ternary heterojunction sensitive material: sintering the PtO2 / SnO2 composite material obtained by grinding in claim 5 at 600-800°C, with a sintering heating rate of 5°C / min and a sintering time of 1-3 h to reduce part of the PtO2 to Pt, thereby obtaining the Pt / PtO2 / SnO2 ternary heterojunction sensitive material.

[0013] Further, the method further comprises a construction step of the ethylene gas sensor based on the sensitive material: grinding the PtO2 / SnO2 sensitive material in claim 5 after mixing with anhydrous ethanol to prepare a sensitive material slurry; coating the slurry on an alumina ceramic tube printed with a gold electrode with a fine brush, and placing it in a muffle furnace for sintering at 600-800°C, with a sintering heating rate of 5°C / min and a sintering time of 1-3 h.

[0014] Further, the sensor construction step further comprises: welding the sintered ceramic tube in claim 7 on a resin base with solder, and inserting a Ni-Cr heating wire in the ceramic tube to provide the required working temperature for the sensitive material, and the resistance of the Ni-Cr heating wire is 27Ω.

[0015] Furthermore, the sensor construction step also includes: placing the device after welding the Ni-Cr heating wire as described in claim 8 on an aging table for aging, with an aging voltage of 2-5V and an aging time of 3-10 days, to obtain a C2H4 gas sensor based on a Pt / PtO2 / SnO2 ternary heterostructure sensitive material.

[0016] Furthermore, the molar percentage content of each component in the sensitive material satisfies the following: the molecular percentage content of SnO2 nanoparticles in the sensitive material is 93% to 99%; the molar percentage content of PtO2 in the sensitive material is 1% to 6%; and the molar percentage content of Pt nanoparticles in the sensitive material is 1% to 6%.

[0017] The beneficial effects of this invention are:

[0018] (1) By using a simple grinding method and a solid-state sintering method to... Load on Successfully prepared on the matrix material Ternary heterostructure sensitive materials; this type of material uses noble metals and noble metal oxides to interact with... The composite ternary heterojunction not only increases a large number of additional active sites and enhances the catalytic activity of the sensitive material, but also further accelerates gas adsorption and electron transfer, thereby improving the gas-sensing performance of the sensitive material for ethylene gas.

[0019] (2) The Pt / PtO2 / SnO2 ternary heterostructure sensitive material prepared by grinding and solid-state sintering can simultaneously form a heterostructure of Pt and PtO2 with SnO2. Furthermore, the Pt and PtO2 nanoparticles derived by solid-state sintering are both excellent catalysts, further increasing the catalytic activity of the sensitive material through the "overflow effect." The Pt / PtO2 / SnO2 structure further enhances the sensitivity material's response to ethylene gas by regulating charge transfer at the material interface. Moreover, by controlling the sintering temperature of the composite material and optimizing the Pt / PtO2 atomic ratio, the active sites of the sensitive material are maximized, enhancing its adsorption capacity for oxygen and ethylene gas at low temperatures, thereby significantly improving the sensor's sensitivity. Simultaneously, the preparation method of this ternary heterostructure sensitive material is simple, with a small proportion of noble metal modification, low cost, and mild conditions, which is conducive to large-scale production.

[0020] (3) By constructing A ternary heterostructure utilizes the difference in work function between different materials to achieve Fermi level equilibrium, forming an electron depletion layer and band bending at the interface. This significantly increases the initial resistivity of the materials, thereby amplifying the minute resistance changes induced by gas reactions and greatly improving the sensor's sensitivity. Furthermore, Pt and... The particles also act as catalysts, optimizing the reaction pathway, lowering the gas reaction barrier, and accelerating the reaction rate. Based on The sensor made of ternary heterostructure sensitive material exhibits a high response value of 69.1 to 500ppm C2H4 at 120℃, which is... It exhibits 12.02 times the performance of a matrix-sensitive material sensor and demonstrates superior gas selectivity and excellent long-term stability against interfering gases generated by lithium-ion batteries. Therefore, Ternary heterostructure sensitive materials have broad prospects in the field of low-temperature high-performance ethylene gas sensitive materials and in monitoring gas production in lithium-ion batteries. Attached Figure Description

[0021] Figure 1 (a) XRD patterns of SnO2 and 700-3%-Pt / PtO2 / SnO2 sensitive materials;

[0022] Figure 1 (b) XPS O 1s spectrum of 700-3%-Pt / PtO2 / SnO2 sensitive material;

[0023] Figure 1 (c) XPS Pt 4f spectrum of 700-3%-Pt / PtO2 / SnO2 sensitive material;

[0024] Figure 1 (d) is a SEM image of the SnO2-sensitive material;

[0025] Figure 1 (ef) is a SEM image of a 700-3%-Pt / PtO2 / SnO2 sensitive material;

[0026] Figure 1 (g) is a TEM image of a 700-3%-Pt / PtO2 / SnO2 sensitive material;

[0027] Figure 1 (h) is an HRTEM image of the PtO2-SnO2 heterojunction of the 700-3%-Pt / PtO2 / SnO2 sensitive material;

[0028] Figure 1 (i) EDS images of Pt, O and Sn for 700-3%-Pt / PtO2 / SnO2 sensitive material;

[0029] Figure 1 (j) is an HRTEM image of a Pt-SnO2 heterojunction for a 700-3%-Pt / PtO2 / SnO2 sensitive material;

[0030] Figure 2(a) Curves showing the relationship between SnO2 sensitive materials modified with PtO2 atomic ratios of 1%, 3%, 5%, and 7% and ethylene gas concentration.

[0031] Figure 2 (b) is a graph showing the relationship between the concentration of 3%-Pt / PtO2 / SnO2 sensitive materials obtained by sintering at 600℃, 700℃, and 800℃ and the concentration of ethylene gas.

[0032] Figure 2 (c) is the response recovery time curve of the 700-3%-Pt / PtO2 / SnO2 sensitive material;

[0033] Figure 2 (d) is the repeatability test curve of the 700-3%-Pt / PtO2 / SnO2 sensitive material;

[0034] Figure 2 (e) shows the selectivity test curves of the 700-3%-Pt / PtO2 / SnO2 sensitive material for different gases;

[0035] Figure 2 (f) shows the long-term stability test curve of the 700-3%-Pt / PtO2 / SnO2 sensitive material;

[0036] Figure 3 (a) is the sensitivity test curve of the 700-3%-Pt / PtO2 / SnO2 sensor to gas production in a 1.5Ah lithium-ion battery;

[0037] Figure 3 (b) Sensor pair with 700-3%-Pt / PtO2 / SnO2 diagram Figure 1 Ah figure shows the sensitivity test curves for gas generation during overpressure thermal runaway in lithium-ion batteries. Detailed Implementation

[0038] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Example 1;

[0040] A method for preparing a Pt / PtO2 / SnO2 ternary heterostructure sensitive material is provided. The sensitive material prepared by the method consists of a SnO2 nanoparticle matrix material and a ternary heterostructure composed of Pt nanoparticles and PtO2.

[0041] The total atomic percentage of Pt and PtO2 in the sensitive material is 3%, and the molar ratio of Pt nanoparticles to PtO2 is 1:2; wherein, the molecular percentage of Pt nanoparticles in the sensitive material is 2%, and the molecular percentage of PtO2 in the sensitive material is 1%.

[0042] The particle sizes of each component in the sensitive material satisfy the following conditions: the particle size of the SnO2 nanoparticle matrix is ​​20-50 nm; the particle size of the Pt nanoparticles is 10 nm to 30 nm; and the particle size of the PtO2 nanoparticles is 5-30 nm.

[0043] The method includes a pretreatment step for the SnO2 nanoparticle matrix: dispersing nano-tin dioxide raw material in a mixed solution of water and ethanol, ultrasonically crushing, centrifuging and drying to obtain SnO2 powder before pretreatment; then sintering the SnO2 powder at 300~600℃, with a sintering heating rate of 5℃ / min and a sintering time of 1~5h to obtain pretreated SnO2 powder.

[0044] The method includes the following steps for preparing the PtO2 / SnO2 composite material: taking the pretreated SnO2 powder from claim 4 and placing it in a mortar, mixing it with PtO2 at an atomic ratio of 1 to 7%, and grinding it to obtain the PtO2 / SnO2 composite material.

[0045] The method includes the following steps for preparing a Pt / PtO2 / SnO2 ternary heterostructure sensitive material: sintering the PtO2 / SnO2 composite material obtained by grinding in claim 5 at 600~800℃, with a sintering heating rate of 5℃ / min and a sintering time of 1~3h, thereby partially reducing PtO2 to Pt to obtain the Pt / PtO2 / SnO2 ternary heterostructure sensitive material.

[0046] The method further includes a step of constructing an ethylene gas sensor based on the aforementioned sensitive material: the PtO2 / SnO2 composite sensitive material described in claim 5 is mixed with anhydrous ethanol and then ground to form a sensitive material slurry; the slurry is coated onto an alumina ceramic tube printed with gold electrodes using a fine brush, placed in a muffle furnace, and sintered at 600℃~800℃, with a sintering heating rate of 5℃ / min and a sintering time of 1~3h, thereby partially reducing PtO2 to Pt.

[0047] The sensor construction step further includes: soldering the sintered ceramic tube of claim 7 onto the resin base with solder, and inserting a Ni-Cr heating wire into the ceramic tube to provide the required operating temperature for the sensitive material, wherein the resistance of the Ni-Cr heating wire is 27Ω.

[0048] The sensor construction step further includes: placing the device after welding the Ni-Cr heating wire as described in claim 8 on an aging table for aging, with an aging voltage of 2 to 5V and an aging time of 3 to 10 days, to obtain a C2H4 gas sensor based on a Pt / PtO2 / SnO2 ternary heterostructure sensitive material.

[0049] The molar percentage content of each component in the sensitive material satisfies the following conditions: the molecular percentage content of SnO2 nanoparticles in the sensitive material is 93% to 99%; the molar percentage content of PtO2 in the sensitive material is 1% to 6%; and the molar percentage content of Pt nanoparticles in the sensitive material is 1% to 6%.

[0050] Example 2: Preparation process of sensitive material based on Pt / PtO2 / SnO2 ternary heterostructure;

[0051] Step 1: Preparation of nano-SnO2 matrix material: Disperse nano-tin dioxide powder in a mixed solution of ethanol and water, sonicate it using an ultrasonic cell disruptor, then wash it with alcohol and deionized water, centrifuge it, dry it in a dryer, and finally sinter the obtained powder in a muffle furnace to obtain the desired nano-SnO2 matrix material powder.

[0052] Step 2: Preparation of nano-Pt / PtO2 / SnO2 ternary heterostructure sensing material: Pretreated SnO2 powder was placed in a mortar and mixed with PtO2, then ground to obtain PtO2 / SnO2 sensing material. Subsequently, the ground PtO2 / SnO2 sensing material was sintered to obtain the Pt / PtO2 / SnO2 ternary heterostructure sensing material.

[0053] Example 3: Specific preparation process of sensitive materials based on Pt / PtO2 / SnO2 ternary heterostructure;

[0054] Step 1: Preparation of nano-SnO2 matrix material: 1.5071g of nano-tin dioxide powder was dispersed in a mixed solution of 40mL ethanol and 20mL deionized water. The suspension was sonicated for 1h using an ultrasonic cell disruptor at 57% power. Then, it was washed by centrifugation with alcohol and deionized water. The centrifuge parameters were set to 8000r / min, 3min each time, for 3 times. The white solid was then dried in an oven at 60℃ for 10h to obtain white powder. Finally, the obtained white powder was sintered in a muffle furnace at 600℃ for 3h to obtain the desired nano-SnO2 matrix material powder.

[0055] Step 2: Preparation of nano-Pt / PtO2 / SnO2 ternary heterostructure sensing material: 0.1507g of pretreated SnO2 powder was placed in a mortar and mixed with PtO2 at an atomic ratio of 1%, 3%, 5%, and 7%. Anhydrous ethanol was added to form a slurry, which was then manually ground for 6 minutes each time, for a total of 5 times, to obtain the PtO2 / SnO2 sensing material. The PtO2 / SnO2 sensing material was then sintered at 700℃ with a heating rate of 5℃ / min and a holding time of 2 hours. After furnace cooling, the Pt / PtO2 / SnO2 ternary heterostructure sensing material was obtained.

[0056] Example 4: Construction of an ethylene gas sensor based on a Pt / PtO2 / SnO2 ternary heterostructure sensitive material;

[0057] Step 1: Sensor fabrication: The Pt / PtO2 ternary heterostructure sensing material (after grinding and before sintering) is mixed with anhydrous ethanol and ground for 5 minutes to prepare a sensing material slurry. The slurry is then evenly coated onto an alumina ceramic tube printed with gold electrodes using a fine brush. The tube is then placed in a muffle furnace and sintered at 700°C. The heating rate of the muffle furnace is 5°C / min, and the sintering time is 2 hours.

[0058] Step 2: Sensor welding and aging: Next, the ceramic tube is soldered to the resin base. A Ni-Cr heating wire is inserted into the ceramic tube to provide the required operating temperature for the sensitive material. The resistance of the Ni-Cr heating wire is 27Ω. The sensor is placed on the aging table for aging. The aging voltage of the sensor is 4.40V and the aging time is 7 days. Finally, a C2H4 gas sensor based on a 700℃-3%Pt / PtO2 / SnO2 ternary heterostructure sensitive material is obtained.

[0059] Example 5: Basic characterization of the sensor's sensitivity to C2H4 gas;

[0060] Figure 1 (a) Shows the relationship curves between ethylene gas concentration and sensor devices modified with PtO2 atomic ratios of 1%, 3%, 5%, and 7% (1%-PtO2 / SnO2, 3%-PtO2 / SnO2, 5%-PtO2 / SnO2, and 7%-PtO2 / SnO2). Specifically, the sensor devices exhibit sensitivity to C2H4 gas concentrations of 300-3000 ppm at 120 °C show that the 3%-PtO2 / SnO2 sensing material exhibits the best sensitivity to ethylene gas. Subsequently, the 3%-PtO2 / SnO2 sensing material is sintered at 700 °C to obtain a 700 °C-3%-Pt / PtO2 / SnO2 sensing material. Figure 1(b) shows the relationship between the 3%-Pt / PtO2 / SnO2 sensitive material obtained by sintering at 600℃, 700℃, and 800℃ and the concentration of ethylene gas. That is, the sensitive response to C2H4 gas with a concentration of 300-3000ppm at a temperature of 120℃ shows that the 700℃-3% Pt / PtO2 / SnO2 sensitive material has the best sensitivity to ethylene gas.

[0061] Repeatability and selectivity tests of ethylene gas were performed on the 700℃-3% Pt / PtO2 / SnO2 sensitive material at 120℃. Figure 1 (c) is the response recovery time curve of the 700-3% Pt / PtO2 / SnO2 sensing material of the device at 120℃ to 500ppm ethylene gas. The response / recovery time of the sensor to 500ppm ethylene gas is 2.6s / 155.5s, which shows that the ternary heterojunction sensor has a fast response speed. Figure 1 (d) shows the five-cycle test curves of the device at 700℃-3% Pt / PtO2 / SnO2 against 500ppm C2H4 gas. It can be seen that this sensitive material exhibits rapid response and recovery to ethylene gas, as well as good repeatability. Furthermore, Figure 1 (e) is the selectivity test curve of the device at 700℃-3% Pt / PtO2 / SnO2 for 500ppm C2H4 and other interfering gases, which shows that the device has excellent selectivity for C2H4. Figure 1 (f) shows the long-term stability test curve of the 700℃-3%-Pt / PtO2 / SnO2 sensing material against 500ppmC2H4 at 120℃ for 30 days, indicating that the sensor has good stability.

[0062] Example 6: Monitoring gas generation in lithium-ion batteries using a ternary heterojunction gas sensor;

[0063] A polymer lithium-ion battery with a nominal voltage of 3.7V and a capacity of 1500mAh was placed in a forced-air drying oven and heated to 150℃ for 20 minutes to induce gas production. Upon contact with the lithium-ion battery and the resulting gas production, the sensor's resistance dropped significantly, indicating that the sensor can detect the gas production in real time. Furthermore, the gas sensor's resistance recovered to its initial value, demonstrating good resilience. This high-performance C2H4 gas sensor can assess the health of lithium-ion batteries by monitoring their gas production, which is significant in the field of lithium-ion battery safety monitoring.

[0064] Example 7: Monitoring gas generation during overvoltage thermal runaway of lithium-ion batteries using a ternary heterojunction gas sensor;

[0065] A polymer lithium-ion battery with a nominal voltage of 3.7V and a capacity of 1000mAh was overcharged to produce gas, and the gas produced by the lithium-ion battery was released by needle puncture. Figure 2 (b) shows the changes in battery temperature, voltage, and gas sensor resistance before the lithium-ion battery thermal runaway. It can be seen that the sensor resistance drops significantly after contact with the lithium-ion battery's gas generation, indicating that the sensor can achieve real-time detection of lithium-ion battery gas generation. Furthermore, Figure 2 (a) The sensitivity test curve of the 700-3%-Pt / PtO2 / SnO2 sensor to gas generation in a 1.5Ah lithium-ion battery further verifies the sensor's response performance to lithium-ion battery gas generation. This ternary heterojunction sensitive material gas sensor provides an early warning of 57s and 66s earlier than voltage and temperature sensors, respectively. Therefore, this high-performance C2H4 gas sensor can be applied to monitor thermal runaway gas generation in lithium-ion batteries, providing a critical safety intervention window for lithium-ion batteries and having significant application value for preventing thermal runaway and ensuring energy storage safety.

[0066] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method for preparing a Pt / PtO2 / SnO2 ternary heterostructure sensitive material, characterized in that, The sensitive material prepared by the method consists of a ternary heterostructure composed of SnO2 nanoparticle matrix material and Pt and PtO2 nanoparticles.

2. The preparation method according to claim 1, characterized in that, The total atomic percentage of Pt and PtO2 in the sensitive material is 3%, and the molar ratio of Pt nanoparticles to PtO2 is 1:2; wherein, the molecular percentage of Pt nanoparticles in the sensitive material is 2%, and the molecular percentage of PtO2 in the sensitive material is 1%.

3. The preparation method according to claim 1, characterized in that, The particle sizes of each component in the sensitive material meet the following requirements: the particle size of the SnO2 nanoparticle matrix is ​​20-50 nm; the particle size of the Pt nanoparticles is 10 nm to 30 nm; and the particle size of the PtO2 nanoparticles is 5-30 nm.

4. The preparation method according to claim 1, characterized in that, The method includes a pretreatment step for the SnO2 nanoparticle matrix: dispersing nano-tin dioxide raw material in a mixed solution of water and ethanol, ultrasonically crushing, centrifuging and drying to obtain SnO2 powder before pretreatment; then sintering the SnO2 powder at 300~600℃, with a sintering heating rate of 5℃ / min and a sintering time of 1~5h to obtain pretreated SnO2 powder.

5. The preparation method according to claim 4, characterized in that, The method includes the following steps for preparing the PtO2 / SnO2 composite material: the SnO2 powder pretreated in claim 4 is placed in a mortar and mixed with PtO2 at an atomic ratio of 1 to 7%, and ground for 15 to 30 minutes to obtain the PtO2 / SnO2 composite material.

6. The preparation method according to claim 5, characterized in that, The method includes the following steps for preparing a Pt / PtO2 / SnO2 ternary heterostructure sensitive material: the PtO2 / SnO2 composite material obtained by grinding in claim 5 is sintered at 500~700℃, the sintering heating rate is 5℃ / min, and the sintering time is 1~3h, thereby partially reducing PtO2 to Pt to obtain the Pt / PtO2 / SnO2 ternary heterostructure sensitive material.

7. The preparation method according to any one of claims 1-6, characterized in that, The method further includes a step of constructing an ethylene gas sensor based on the sensitive material: mixing the PtO2 raw material and SnO2 sensitive material according to any one of claims 1-6 with anhydrous ethanol and grinding them to prepare a sensitive material slurry; applying the slurry to an alumina ceramic tube printed with gold electrodes with a fine brush, placing it in a muffle furnace, and sintering it at 600℃~800℃, with a sintering heating rate of 5℃ / min and a sintering time of 1~3h.

8. The preparation method according to claim 7, characterized in that, The sensor construction step further includes: soldering the sintered ceramic tube of claim 7 onto the resin base with solder, and inserting a Ni-Cr heating wire into the ceramic tube to provide the required operating temperature for the sensitive material, wherein the resistance of the Ni-Cr heating wire is 27Ω.

9. The preparation method according to claim 8, characterized in that, The sensor construction step further includes: placing the device after welding the Ni-Cr heating wire as described in claim 8 on an aging table for aging, with an aging voltage of 2-5V and an aging time of 3-10 days, to obtain a C2H4 gas sensor based on a Pt / PtO2 / SnO2 ternary heterostructure sensitive material.

10. The preparation method according to claim 1, characterized in that, The molar percentage content of each component in the sensitive material satisfies the following: the molecular percentage content of SnO2 nanoparticles in the sensitive material is 93% to 99%; the molar percentage content of PtO2 in the sensitive material is 1% to 6%; and the molar percentage content of Pt nanoparticles in the sensitive material is 1% to 6%.

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