Au-modified hollow spherical SnO2 nanocomposite and its hydrogen sensor preparation method

Abstract

The present invention discloses an Au-modified hollow spherical SnO2 nanocomposite and a method for preparing a hydrogen sensor. Based on the synthesis of hollow spherical SnO2 nanoparticles via a one-step hydrothermal synthesis method, the amount of concentrated hydrochloric acid in the mixed solution is reduced and the HAuCl4·4H2O doping ratio is controlled to produce an Au-modified hollow spherical SnO2 nanocomposite with a unique micromorphology. This method addresses the low response and long response / recovery times of existing metal oxide semiconductor (MOS) hydrogen sensors at low temperatures. By doping the material with catalytic Au, the material system is enhanced in terms of conductivity and reactivity at lower temperatures, while the specific surface area is increased by micromorphological manipulation to enhance the response. This method offers advantages such as simple material preparation, high hydrogen response at low operating temperatures, and short response / recovery times. Given the vigorous development of hydrogen energy, the development of such intrinsically safe low-temperature hydrogen sensors holds great promise for future applications.

Description

Technical Field

[0001] The invention belongs to the technical field of gas detection, and particularly relates to an Au-modified hollow spherical SnO2 nanocomposite material and a preparation method of a hydrogen sensor thereof. Background Art

[0002] As a green, clean, and sustainable clean energy source, hydrogen is widely used in fields such as petrochemicals, aerospace, and fuel cells. At the same time, in the process of electrochemical energy storage, hydrogen, as the first flammable gas released by lithium-ion batteries during thermal runaway, is one of the important alarm parameters for the very early warning of thermal runaway in lithium-ion batteries. However, due to the dangerous properties of hydrogen, such as being colorless, odorless, with extremely low ignition energy, and being flammable and explosive, the safe detection of hydrogen leaks poses many challenges. As hydrogen energy plays an increasingly important role in my country's new energy system, safe, fast, accurate, and economical hydrogen detection is of great significance.

[0003] Among the many gas sensor types, including optical, electrochemical, thermal conductivity, and semiconductor, metal oxide semiconductor materials such as SnO2, ZnO, CuO, and Fe2O3, as typical semiconductor resistive sensor materials, are widely used in the field of combustible gas detection due to their high responsiveness, low cost, excellent stability, and ease of miniaturization. Among them, SnO2, a metal oxide semiconductor material with a wide range of sources, simple preparation process, broad band structure, and stable response, is widely used in various semiconductor resistive sensors. However, hydrogen sensors prepared with pure SnO2 as the core material often face problems such as high operating temperatures and long response / recovery times, which greatly hinder their application in hydrogen detection and pose the risk of high-temperature ignition during the detection of combustible gases such as hydrogen. The rapid development of hydrogen energy continues to pose new requirements and challenges for the application scenarios of hydrogen sensors. The development of detection materials sensitive to hydrogen at lower operating temperatures and intrinsically safe hydrogen sensors has important application value and practical significance.

[0004] Some researchers have pointed out that the doping of precious metals such as Au, Pt, and Pd can improve the performance of metal oxide semiconductor materials in gas detection, acting as a surface catalyst. Furthermore, due to Au's strong conductive properties, it can significantly improve the conductivity of the composite material. Furthermore, by controlling the material's micromorphology, SnO2 nanocomposites with adjusted size and structure have a large specific surface area, which helps enhance the interfacial reaction between gas molecules and the material surface, improving gas detection performance. Currently, domestic research and development of gas sensing materials focuses primarily on elemental doping or basic morphology control. There is little research and development of composite nanomaterials for hydrogen sensors that maintain a specific micromorphology while introducing catalytic metal doping.

[0005] Based on real-world application scenarios and combined with experimental and new technology research and development needs, this paper proposes a method for preparing Au-modified hollow spherical SnO2 nanocomposites for hydrogen sensors. The aim is to improve the performance of traditional sensors used for hydrogen detection through morphology control and catalytic metal modification, reduce the operating temperature of the sensor, and improve the intrinsic safety of such sensors. Summary of the Invention

[0006] To solve the above problems, the present invention adopts a one-step hydrothermal synthesis method, uses Au as a noble metal catalyst, and simultaneously adjusts the conductive properties of the nanocomposite material. By controlling the amount of concentrated hydrochloric acid and the HAuCl4·4H2O doping ratio, the material morphology is maintained in a hollow spherical structure. Through a simple synthesis method, an Au-modified hollow spherical SnO2 nanocomposite material is prepared, which uses SnO2 as the core sensitive material and Au is loaded on the surface of SnO2 clusters and then self-assembled to form an Au-modified hollow spherical SnO2 nanocomposite material. The morphology of traditional SnO2-based sensitive materials is controlled and the performance is improved, which greatly improves the hydrogen responsiveness and stability of SnO2-based hydrogen sensors at lower operating temperatures, providing a new method for the research and development of intrinsically safe metal oxide semiconductor hydrogen sensors.

[0007] The present invention first proposes an Au-modified hollow spherical SnO2 nanocomposite material. The material morphology is a hollow spherical structure composed of nanoclusters, wherein catalytic metal Au is distributed on the surface of the SnO2 nanoclusters forming the spheres.

[0008] The present invention provides a method for preparing an Au-modified hollow spherical SnO2 nanocomposite material, comprising the following steps:

[0009] Step 1: Prepare a mixed solution of anhydrous ethanol and deionized water, add the tin source and the gold source to the mixed solution, stir evenly, add acid, and ultrasonically disperse to form a uniform mixed solution;

[0010] Step 2: pouring the mixed solution into a reactor for hydrothermal reaction, then cooling to room temperature, and centrifuging to obtain a solid product;

[0011] Step 3: After the solid product is dried and sintered, an Au-modified hollow spherical SnO2 nanocomposite material is obtained.

[0012] Furthermore, in step 1, the volume ratio of anhydrous ethanol to deionized water is 10:1.

[0013] Furthermore, in step 1, the volume of the mixed solution of anhydrous ethanol and deionized water is 20 to 30 mL.

[0014] Furthermore, in step 1, the tin source is SnCl4·5H2O, and the gold source is HAuCl4·4H2O.

[0015] Furthermore, in step 1, the amount of SnCl4·5H2O used is 0.5 mmol; the molar ratio of SnCl4·5H2O to HAuCl4·4H2O is 1:0.01-0.05.

[0016] Furthermore, in step 1, the acid is concentrated hydrochloric acid with a mass fraction of 36.5%; and the ultrasonic dispersion time is 40 minutes.

[0017] Furthermore, in step 1, the volume of concentrated hydrochloric acid added to the mixed solution is 0.3 to 0.5 mL.

[0018] Furthermore, in step 2, a 50 mL stainless steel autoclave lined with polytetrafluoroethylene is used. The hydrothermal reaction temperature is 180-200° C., and the hydrothermal reaction time is 22-24 hours.

[0019] Furthermore, step 2 is specifically as follows: pouring the uniformly mixed solution into a 50 mL high-pressure reactor, maintaining a hydrothermal reaction at 180-200° C. for 22-24 hours, and naturally cooling to room temperature; centrifuging the reaction mixture, and repeatedly washing and centrifuging 3-5 times with a mixed solution of deionized water and anhydrous ethanol to obtain a solid product.

[0020] Furthermore, in step 3, the solid product is dried and sintered, comprising: placing the separated solid product in a vacuum oven at a temperature of 50-60° C. and drying for 12-14 hours; placing the dried solid product in a muffle furnace and heating it to 380-420° C. at a rate of 4-5° C. / min, sintering for 4-6 hours, and naturally cooling to room temperature.

[0021] Preferably, in step 1, the volume of the mixed solution of anhydrous ethanol and deionized water is 20-30 mL; the amount of SnCl4·5H2O used is 0.5 mmol; the molar ratio of SnCl4·5H2O to HAuCl4·4H2O is 1:0.01-0.05; the acid is concentrated hydrochloric acid with a mass fraction of 36.5%; and the ultrasonic dispersion time is 40 min.

[0022] More preferably, in step 1, the volume of concentrated hydrochloric acid added to the mixed solution is 0.3 to 0.5 mL.

[0023] The present invention provides a hydrogen sensor comprising a nanocomposite material prepared by the above method, wherein a gold interdigital electrode is used as a sensitive electrode, the nanocomposite material is evenly dripped onto the gold interdigital electrode, and platinum electrodes are used as connecting pins to connect the two ends of the gold interdigital electrode.

[0024] The present invention also provides a method for preparing the hydrogen sensor as described above, comprising the following steps:

[0025] Step 1: Mix the nanocomposite material and terpineol and disperse them uniformly by ultrasonication, then drip the dispersed solution onto the gold interdigital electrode and dry it in an oven at 50-70°C.

[0026] Step 2: scraping off the composite material covering both ends of the dried gold interdigital electrode, then placing the gold interdigital electrode with the composite nanomaterial into a muffle furnace, heating to 380-400° C. at a heating rate of 4-6° C. / min for sintering, and naturally cooling to room temperature;

[0027] Step 3: The exposed parts of the two ends of the sintered gold interdigitated electrodes are connected to platinum electrodes and aged in an air environment at 350-450°C to obtain a hydrogen sensor prepared based on the Au-modified hollow spherical SnO2 nanocomposite material.

[0028] Preferably, in step 1, the mass of the nanocomposite material is 15 to 30 mg; the amount of terpineol used is 0.3 to 1.0 mL; and the volume of the dispersed solution absorbed is 10 to 30 μL.

[0029] Preferably, in step 2, the sintering time is controlled to be 3 to 6 hours.

[0030] More preferably, in step 3, the aging time is controlled within 4 to 6 days.

[0031] The present invention uses Au as a noble metal catalyst and utilizes its unique electrical properties to regulate the conductive properties of the nanocomposite material. At the same time, the material morphology is maintained as a hollow spherical structure by controlling the ratio of reactants. A simple synthesis method is used to prepare an Au-modified hollow spherical SnO2 nanocomposite material with SnO2 as the core sensitive material, and Au is loaded on the surface of SnO2 clusters and then self-assembled to form an Au-modified hollow spherical SnO2 nanocomposite material. Based on this, a high-performance sensor sensitive to hydrogen at a lower operating temperature is prepared, which is used in related gas detection scenarios with high requirements for the intrinsic safety of the detector.

[0032] The advantages of the present invention compared with the prior art are:

[0033] The present invention provides a method for preparing Au-modified hollow spherical SnO2 nanocomposite materials that are sensitive to hydrogen at relatively low operating temperatures. A SnO2-based hydrogen-sensitive material that maintains a hollow spherical structure after Au doping is prepared through a one-step hydrothermal synthesis method. The material not only exhibits enhanced responsiveness but also possesses a large specific surface area. When the nanocomposite material is prepared into a sensor using the method described herein, its response temperature to hydrogen is significantly reduced, offering the advantage of being sensitive to hydrogen at relatively low temperatures. The material also exhibits enhanced response values ​​and response / recovery times, improving the safety and stability of the sensor in hydrogen detection applications and providing a new approach for the development of intrinsically safe metal oxide semiconductor hydrogen sensors. Specifically, the following aspects are addressed:

[0034] (1) First, the one-step hydrothermal synthesis method is adopted, which has the advantages of being simple and easy to operate in terms of preparation method;

[0035] (2) Au is used as a catalytic noble metal and is uniformly doped on SnO2 clusters as surface catalytic sites. Au not only provides reactive centers to improve the hydrogen response value of the composite material system, but also utilizes Au's unique electrical properties to improve the conductivity of the system, greatly improving the gas detection performance of the composite material at lower temperatures.

[0036] (3) The preparation method provided by the present invention can prepare a nanocomposite material with a stable and controllable micromorphology. By controlling the amount of hydrochloric acid in the solution and the HAuCl4·4H2O doping ratio, an Au-modified hollow spherical SnO2 nanocomposite material with a special micromorphology is obtained, so that the material can maintain a high specific surface area, increase the contact area between gas molecules and the material, and enhance the responsiveness of the composite material system.

[0037] (4) The hydrogen detector prepared by the method of the present invention has the advantages of good stability and high responsiveness at lower operating temperatures. After completing the sintering and aging process, the prepared detector not only has significant improvements in responsiveness and sensitivity compared with traditional commercial combustible gas sensors, but also has a significant response to low-concentration hydrogen at lower operating temperatures, greatly improving the intrinsic safety of the sensor.

[0038] The method of the present invention has the advantages of a simple material preparation process and high responsiveness and stability to low-concentration hydrogen at relatively low operating temperatures. It has broad prospects in the future given the huge demand for multi-scenario applications of intrinsically safe hydrogen sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 Schematic diagram of the self-assembly process of the Au-modified hollow spherical SnO2 nanocomposite material prepared in Example 4 of the present invention and a scanning electron microscope image of the hollow structure.

[0041] Figure 2 This is a transmission electron microscopy image of the Au-modified hollow spherical SnO2 nanocomposite material prepared in Example 4 of the present invention.

[0042] Figure 3 This is the XRD data diagram of the Au-modified hollow spherical SnO2 nanocomposite material prepared in Example 4 of the present invention.

[0043] Figure 4 The basic resistance curves of sensors prepared from the hollow spherical pure phase SnO2 nanomaterials and Au-modified hollow spherical SnO2 nanocomposites prepared in Examples 1 and 4 of the present invention at different temperatures in air.

[0044] Figure 5 Response curves of sensors prepared from the hollow spherical pure-phase SnO2 nanomaterials and Au-modified hollow spherical SnO2 nanocomposites prepared in Examples 1 and 4 of the present invention to 100 ppm hydrogen at a relatively low operating temperature of 120°C.

[0045] Figure 6 Response curves of sensors prepared from the hollow spherical pure-phase SnO2 nanomaterials and Au-modified hollow spherical SnO2 nanocomposites prepared in Examples 1 and 4 of the present invention to 100 ppm hydrogen in a higher operating temperature range. DETAILED DESCRIPTION

[0046] The following is a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings. Obviously, the described embodiments are only some preferred embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0047] The present invention employs the following equipment:

[0048] The scanning electron microscope used a GeminiSEM 450 field emission scanning electron microscope from Zeiss, Germany, the transmission electron microscope used a Talos F200X from FEI, and the XRD experiment was completed using a Smartlab multifunctional rotating target X-ray diffractometer.

[0049] Example 1:

[0050] First, 22 mL of a mixed solution of anhydrous ethanol and deionized water in a volume ratio of 10:1 was prepared, and 0.5 mmol (0.1753 g) of SnCl4·5H2O was weighed and added to the mixed solution. The solution was stirred at 30°C for 30 min. After mixing evenly, 0.5 mL of concentrated hydrochloric acid with a mass fraction of 36.5% was slowly added dropwise, and the mixed solution was ultrasonically mixed for 40 min.

[0051] After ultrasonic dispersion, the homogeneous mixed solution was transferred to a 50 mL stainless steel autoclave lined with polytetrafluoroethylene. The reaction was maintained at 200°C for 20 hours and then naturally cooled to room temperature. After the reaction was complete, the mixed solution was centrifuged for 15 minutes and washed four times with a mixture of anhydrous ethanol and deionized water in a 10:1 volume ratio to obtain the precipitated product.

[0052] The lower precipitate obtained above was placed in a vacuum oven and dried at 60°C for 10 hours. The dried solid product was placed in a muffle furnace and heated to 380°C at a rate of 4°C / min. After sintering for 5 hours, it was naturally cooled to room temperature to prepare hollow spherical pure SnO2 nanomaterials.

[0053] Example 2:

[0054] First, 22 mL of a mixed solution of anhydrous ethanol and deionized water in a volume ratio of 10:1 was prepared, and 0.5 mmol (0.1753 g) of SnCl4·5H2O and 0.005 mmol (0.0021 g) of HAuCl4·4H2O were weighed and added to the mixed solution. The mixture was stirred at 30°C for 30 min. After mixing evenly, 0.4 mL of concentrated hydrochloric acid with a mass fraction of 36.5% was slowly added dropwise, and the mixed solution was ultrasonically mixed for 40 min.

[0055] After ultrasonic dispersion, the homogeneous mixed solution was transferred to a 50 mL stainless steel autoclave lined with polytetrafluoroethylene. The reaction was maintained at 200°C for 20 hours and then naturally cooled to room temperature. After the reaction was complete, the mixed solution was centrifuged for 15 minutes and washed four times with a mixture of anhydrous ethanol and deionized water in a 10:1 volume ratio to obtain the precipitated product.

[0056] The lower precipitate was dried in a vacuum oven at 60°C for 10 hours. The dried solid product was placed in a muffle furnace and heated to 380°C at a rate of 4°C / min. After sintering for 5 hours, it was naturally cooled to room temperature to prepare an Au-modified hollow spherical SnO2 nanocomposite material.

[0057] Example 3:

[0058] First, 22 mL of a mixed solution of anhydrous ethanol and deionized water in a volume ratio of 10:1 was prepared, and 0.5 mmol (0.1753 g) of SnCl4·5H2O and 0.0125 mmol (0.0052 g) of HAuCl4·4H2O were weighed and added to the mixed solution. The mixture was stirred at 30°C for 30 min. After mixing evenly, 0.3 mL of concentrated hydrochloric acid with a mass fraction of 36.5% was slowly added dropwise, and the mixed solution was ultrasonically mixed for 40 min.

[0059] After ultrasonic dispersion, the homogeneous mixed solution was transferred to a 50 mL stainless steel autoclave lined with polytetrafluoroethylene. The reaction was maintained at 200°C for 20 hours and then naturally cooled to room temperature. After the reaction was complete, the mixed solution was centrifuged for 15 minutes and washed four times with a mixture of anhydrous ethanol and deionized water in a 10:1 volume ratio to obtain the precipitated product.

[0060] The lower precipitate obtained above was dried in a vacuum oven at 60°C for 10 hours. The dried solid product was placed in a muffle furnace and heated to 380°C at a rate of 4°C / min. After sintering for 5 hours, it was naturally cooled to room temperature to prepare an Au-modified hollow spherical SnO2 nanocomposite material.

[0061] Example 4:

[0062] First, 22 mL of a mixed solution of anhydrous ethanol and deionized water in a volume ratio of 10:1 was prepared, and 0.5 mmol (0.1753 g) of SnCl4·5H2O and 0.025 mmol (0.0102 g) of HAuCl4·4H2O were weighed and added to the mixed solution. The mixture was stirred at 30°C for 30 min. After mixing evenly, 0.3 mL of concentrated hydrochloric acid with a mass fraction of 36.5% was slowly added dropwise, and the mixed solution was ultrasonically mixed for 40 min.

[0063] After ultrasonic dispersion, the homogeneous mixed solution was transferred to a 50 mL stainless steel autoclave lined with polytetrafluoroethylene. The reaction was maintained at 200°C for 20 hours and then naturally cooled to room temperature. After the reaction was complete, the mixed solution was centrifuged for 15 minutes and washed four times with a mixture of anhydrous ethanol and deionized water in a 10:1 volume ratio to obtain the precipitated product.

[0064] The lower precipitate obtained above was placed in a vacuum oven at 60°C and dried for 10 hours. The dried solid product was placed in a muffle furnace and heated to 380°C at a rate of 4°C / min. After sintering for 5 hours, it was naturally cooled to room temperature to prepare Au-modified hollow spherical SnO2 nanocomposites, such as Figure 1 As shown, this is a schematic diagram of the self-assembly process of the Au-modified hollow spherical SnO2 nanocomposite material prepared in Example 4 of the present invention and a scanning electron microscope image of the hollow structure. It can be seen that with SnO2 as the core sensitive material, Au is loaded on the surface of the SnO2 cluster and then self-assembled to form an Au-modified hollow spherical SnO2 nanocomposite material structure.

[0065] Figure 2 This is a transmission electron microscopy image of the Au-modified hollow spherical SnO2 nanocomposite material prepared in Example 4 of the present invention. The hollow structure in the middle of the spherical composite material can also be clearly seen from the transmission electron microscope.

[0066] Figure 3 This is the XRD data diagram of the Au-modified hollow spherical SnO2 nanocomposite material prepared in Example 4 of the present invention (Smartlab multifunctional rotating target X-ray diffractometer). The XRD data show the successful doping of Au and its presence on the surface, which confirms the assembly process proposed by this method.

[0067] Example 5:

[0068] 15 mg of the nanomaterials prepared in Examples 1 to 4 was added with 0.5 mL of terpineol and mixed, followed by ultrasonic treatment for 1 hour to obtain a uniformly dispersed mixed solution A. 20 μL of solution A was slowly and evenly dripped onto a 10 mm × 15 mm gold interdigitated electrode using a pipette, and then dried in a vacuum oven at 60°C for 12 hours.

[0069] After drying, the material covering both ends of the electrode was scraped off with a blade, and the gold interdigitated electrode covered with the nanocomposite material was placed in a muffle furnace, heated to 380°C at a heating rate of 5°C / min, kept at this temperature for 5 hours, and cooled to room temperature.

[0070] After connecting the exposed parts of the gold interdigitated electrodes to platinum electrodes and aging them in an air environment at 400°C for 4 days, a hydrogen sensor with stable performance based on Au-modified hollow spherical SnO2 nanocomposite materials was obtained.

[0071] Figure 4The baseline resistance curves of sensors prepared from the hollow spherical pure-phase SnO2 nanomaterials and Au-modified hollow spherical SnO2 nanocomposites prepared in Examples 1 and 4 of the present invention at different temperatures in air show that at relatively low temperatures below 120°C, the resistance of the Au-modified SnO2 nanocomposite is significantly lower than that of pure-phase SnO2. At 90°C, the pure-phase resistance is approximately 22.8 MΩ, while the Au-modified SnO2 nanocomposite is only approximately 1.3 MΩ. This demonstrates that the Au modification enhances the material's electrical conductivity and enables it to maintain a low baseline resistance, which is beneficial to sensor stability.

[0072] Figure 5 The response curves of the sensors prepared from the hollow spherical pure phase SnO2 nanomaterials and the Au modified hollow spherical SnO2 nanocomposite materials prepared in Examples 1 and 4 of the present invention to 100 ppm hydrogen at a lower operating temperature of 120°C are shown in FIG. Figure 5 It can be seen that the Au-modified composite material has a response value of about 1.7 to 100ppm hydrogen at a low operating temperature of 120°C, and has a clear response pulse step, while the pure SnO2 material has no obvious response at this temperature. This shows that the modification of Au enables the material to complete the response detection of hydrogen at a lower temperature. Compared with most current combustible gas sensors with an operating temperature of 300-500°C, the response temperature for hydrogen detection is greatly reduced, which provides a strong guarantee for the intrinsic safety of such sensors.

[0073] Figure 6 The following are response curves of sensors prepared from the hollow spherical pure-phase SnO2 nanomaterials and Au-modified hollow spherical SnO2 nanocomposites prepared in Examples 1 and 4 of the present invention to 100 ppm hydrogen in a higher operating temperature range. It can be seen that compared to traditional pure-phase SnO2 nanomaterials, the sensors prepared from the Au-modified hollow spherical SnO2 nanocomposites proposed in the present invention have higher response values ​​and shorter response / recovery times even in a higher operating temperature range. At 420°C, the response value can reach 7.3, while that of pure-phase SnO2 is only about 4.3. These improved performances provide more possibilities for the promotion of such hydrogen sensors in different application scenarios. They can perform detection at lower operating temperatures in hazardous locations, as well as perform high-performance hydrogen detection at high operating temperatures.

[0074] Parts of the present invention that are not described in detail belong to the well-known technology in the art.

[0075] Although the above describes the illustrative specific embodiments of the present invention to facilitate understanding of the present invention by those skilled in the art, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concepts of the present invention are protected.

Claims

1. A hydrogen sensor based on Au-modified hollow spherical SnO2 nanocomposite material, characterized by: The hydrogen sensor is prepared by the following method: First, 22 mL of a mixed solution of anhydrous ethanol and deionized water in a volume ratio of 10:1 was prepared. 0.5 mmol SnCl4·5H2O and 0.025 mmol HAuCl4·4H2O were weighed and added to the mixed solution. The mixture was stirred at 30°C for 30 min. After mixing, 0.3 mL of 36.5% concentrated hydrochloric acid was slowly added dropwise. The mixed solution was ultrasonically mixed for 40 min. After ultrasonic dispersion, the homogeneous mixed solution was transferred to a 50 mL stainless steel autoclave lined with polytetrafluoroethylene, maintained at 200 °C for 20 hours, and then naturally cooled to room temperature. After the reaction was completed, the mixed solution was centrifuged for 15 minutes and repeatedly washed four times with a mixture of anhydrous ethanol and deionized water in a volume ratio of 10:1 to obtain the lower layer precipitate product. The lower precipitate obtained above was placed in a vacuum oven at 60°C and dried for 10 hours. The dried solid product was placed in a muffle furnace and heated to 380°C at a rate of 4°C / min. After sintering for 5 hours, it was naturally cooled to room temperature to prepare an Au-modified hollow spherical SnO2 nanocomposite material. The Au-modified hollow spherical SnO2 nanocomposite material structure was formed by self-assembly after Au was loaded on the surface of SnO2 clusters with SnO2 as the core sensitive material. 15 mg of the Au-modified hollow spherical SnO2 nanocomposite was added to 0.5 mL of terpineol and mixed, followed by ultrasonic treatment for 1 hour to obtain a uniformly dispersed mixed solution A. 20 μL of solution A was slowly and evenly dripped onto a 10 mm × 15 mm gold interdigitated electrode using a pipette, and then dried in a vacuum oven at 60 °C for 12 hours. After drying, the material covering both ends of the electrode was scraped off with a blade, and the gold interdigitated electrode coated with the nanocomposite material was placed in a muffle furnace and heated to 380 °C at a heating rate of 5 °C / min, kept at this temperature for 5 h, and cooled to room temperature. After connecting the exposed ends of the gold interdigitated electrodes to platinum electrodes and aging them in air at 400°C for 4 days, a stable hydrogen sensor based on Au-modified hollow spherical SnO2 nanocomposite materials was obtained. The hydrogen sensor prepared based on the Au-modified hollow spherical SnO2 nanocomposite material has a response value of 1.7 to 100 ppm hydrogen at a relatively low operating temperature of 120°C and has a response pulse step.

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