Composite gas-sensitive material based on semiconductor metal oxide, preparation method of composite gas-sensitive material and application of composite gas-sensitive material in hydrogen sulfide sensor

Abstract

The invention discloses a composite gas-sensitive material based on a semiconductor metal oxide, a preparation method of the composite gas-sensitive material and application of the composite gas-sensitive material in a hydrogen sulfide sensor, and belongs to the technical field of hydrogen sulfide sensors. The composite gas-sensitive material is used for a gas-sensitive layer of a hydrogen sulfide sensor, low-temperature rapid detection of low-concentration hydrogen sulfide is achieved in a material compounding and morphology regulation mode without precious metal modification, meanwhile, excellent selectivity of hydrogen sulfide gas is achieved, the ubiquitous problems of hydrogen sulfide sensors in the prior art are solved, and the hydrogen sulfide sensor has good application prospects. The energy consumption of the sensor is greatly reduced, the application scene of the sensor is widened, and possibility is provided for applying the sensor to emerging application scenes such as portable medical detection equipment in the future.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen sulfide sensors, and in particular relates to a composite gas-sensitive material based on semiconductor metal oxides, a preparation method thereof, and an application of the composite gas-sensitive material in hydrogen sulfide sensors. Background Art

[0002] Hydrogen sulfide (H2S) is a colorless, flammable, toxic, corrosive, and pungent small molecule gas that is closely related to global industrial production and daily life. As an atmospheric pollutant, hydrogen sulfide poses a serious threat to human health and equipment safety due to its strong toxicity, strong reducing properties, and its ability to form an acidic solution when in contact with water, making it one of the most dangerous gases in many working environments. Furthermore, in the healthcare sector, the use of hydrogen sulfide sensors to measure the concentration of hydrogen sulfide in a patient's exhaled breath enables intelligent and convenient diagnosis of conditions such as bad breath and chronic pancreatitis, making it a highly promising emerging detection technology. Therefore, the development of high-performance, long-life hydrogen sulfide gas sensors that can effectively, stably, and rapidly detect low-concentration hydrogen sulfide gas for environmental and health monitoring and hazard warning purposes is a key category in gas sensor research and development, with broad market demand and enormous application value.

[0003] Semiconductor metal oxide hydrogen sulfide sensors have become the mainstream type of hydrogen sulfide sensor due to their simple structure, ease of preparation, and good stability. Common gas-sensitive materials such as SnO2 and CuO are widely used due to their excellent performance in hydrogen sulfide detection. However, single semiconductor metal oxide hydrogen sulfide sensors often suffer from drawbacks such as high operating temperature, poor selectivity, and difficulty detecting low-concentration hydrogen sulfide. These issues not only increase energy consumption but also restrict their scope of application. Currently, the mainstream method for optimizing sensor performance is to reduce the operating temperature, improve selectivity, and enhance low-concentration hydrogen sulfide detection capabilities through catalytic modification with precious metals (such as Pd and Pt), but this inevitably increases the manufacturing cost of the sensor significantly.

[0004] Atomic layer deposition (ALD) is an advanced material preparation technology. ALD is a special type of chemical vapor deposition that forms a thin film by alternately introducing pulses of gaseous precursors into a reaction chamber, causing a chemical adsorption reaction on the substrate surface. Utilizing its unique self-limiting and self-saturation properties, ALD achieves precise control of the film's thickness and composition at the atomic scale, ensuring excellent three-dimensional conformability and large-area uniformity of the gas-sensitive material, which is beneficial for optimizing the device's sensing performance. In addition, due to the characteristics of ALD technology, it is very suitable for compatibility with microelectromechanical (MEMS) systems to prepare ultra-thin, composite, and integrated multifunctional sensors. However, there are currently few studies combining ALD technology with hydrogen sulfide sensor preparation. Therefore, extensive and in-depth exploratory research is urgently needed to develop hydrogen sulfide sensors with excellent comprehensive performance. Summary of the Invention

[0005] The present invention provides a composite gas-sensitive material based on semiconductor metal oxides, a preparation method thereof, and an application in a hydrogen sulfide sensor. By combining ALD technology with a hydrothermal method on an insulating inorganic or polymer substrate, a SnO2@CuO composite material is prepared as a gas-sensitive layer, achieving high sensitivity, low temperature, and rapid response to low-concentration hydrogen sulfide, while also achieving excellent selectivity for hydrogen sulfide gas.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions: A method for preparing a composite gas-sensitive material based on semiconductor metal oxides comprises the following steps: (1) Synthesis of CuO powder with nanosheet structure; (2) On the synthesized CuO powder, SnO2 thin film was deposited by ALD technology for 20-200 cycles to obtain SnO2@CuO composite gas-sensitive material.

[0007] In the above steps, a hydrothermal method is used to synthesize CuO powder with a nanosheet structure. The specific process is as follows: 1.5-3.5g of Cu(CH3COO)2·H2O is dissolved in 20-60ml of deionized water, 5-20ml of NH3·H2O is slowly added, and magnetic stirring is performed; then 0.4-1.8g of NaOH is added, and stirring is continued for 20-60 minutes. The mixed solution is poured into a reactor and heated at 150-200°C. After obtaining a powder, it is washed with ethanol and deionized water 2-5 times each, and dried to obtain CuO powder with a nanosheet structure; ALD deposition is performed at room temperature to 200°C. The tin source used is tetrakis(dimethylamino)tin (TDMSn) or SnCl4, and the oxygen source is water, ozone, or plasma oxygen. The tin source temperature is 60°C to 100°C. The pulse and purge times of the tin source are 0.1 s to 0.6 s and 6.0 s to 15 s, respectively. The pulse and purge times of the oxygen source are 0.1 s to 30 s and 5 s to 25 s, respectively. The gas flow rate is 150 sccm.

[0008] The semiconductor metal oxide-based composite gas-sensitive material prepared by the above method is a SnO2@CuO composite material formed by CuO powder coated with SnO2 thin film. The SnO2@CuO composite material has a nanosheet structure, and the SnO2 exists in an amorphous form.

[0009] The above-mentioned composite gas-sensitive material based on semiconductor metal oxide is applied to a hydrogen sulfide sensor. The preparation method of the hydrogen sulfide sensor comprises the following steps: (1) Ultrasonic cleaning of the insulating substrate was performed with acetone, isopropyl alcohol, anhydrous ethanol, and deionized water in sequence for 5 minutes, and then blown dry with high-purity nitrogen (99.999%) for later use; (2) The SnO2@CuO composite gas-sensitive material powder synthesized above was dissolved in an ethanol solution and uniformly coated on the treated insulating substrate by a drop coating method to form a SnO2@CuO composite gas-sensitive layer; (3) Using a mask, a metal interdigitated electrode with a thickness of 100-200 nm is deposited on the SnO2@CuO composite gas-sensitive layer as a conductive electrode. After wiring and packaging, a SnO2@CuO composite hydrogen sulfide sensor can be obtained.

[0010] The insulating substrate is an inorganic substrate or a polymer substrate.

[0011] The prepared hydrogen sulfide sensor comprises, from bottom to top, an insulating substrate, a semiconductor metal oxide composite gas-sensitive layer, and a conductive electrode layer; the semiconductor metal oxide composite gas-sensitive layer is a SnO2@CuO composite material formed by CuO powder coated with SnO2 film.

[0012] Beneficial effects: The present invention provides a composite gas-sensitive material based on semiconductor metal oxides, a preparation method thereof, and an application in a hydrogen sulfide sensor, which has the following advantages over the prior art: 1. The present invention first synthesizes CuO with a nanosheet morphology. The nanosheet structure is conducive to increasing the specific surface area, providing a higher specific surface area for the sensor. In addition, the gaps and channels between the nanosheets can form unique gas diffusion channels, providing a more convenient diffusion path for gas molecules, which helps hydrogen sulfide gas to quickly reach the active area of ​​the sensor, thereby improving the gas-sensitive performance of the sensor, and also improving the sensor's ability to detect hydrogen sulfide in a low-temperature environment; then, ALD technology is used to grow an amorphous SnO2 thin film uniformly coated on the CuO surface through atomic-level self-limiting growth, thereby achieving uniform compounding of the material, which is conducive to improving the consistency of the sensor; the method of the present invention achieves low-temperature rapid detection of low-concentration hydrogen sulfide through material compounding and morphology control without precious metal modification, and at the same time achieves excellent selectivity for hydrogen sulfide gas.

[0013] 2. The present invention adopts SnO2@CuO composite material as gas-sensitive material. When SnO2 (n-type semiconductor) is deposited on the surface of CuO (p-type semiconductor) nanosheets, the two form a pn junction. Electrons at the interface migrate from SnO2 to CuO, forming an electron depletion layer on the SnO2 side, resulting in a significant decrease in the electron density of SnO2. The depletion layer formed by the surface oxygen capturing electrons in the air environment is further expanded, and the initial resistance is greatly increased (electron sensitization effect); when exposed to hydrogen sulfide gas, hydrogen sulfide reacts chemically with oxygen adsorbed on the SnO2 surface, releasing electrons back to the sensor, and the potential barrier is lowered. Since the initial resistance of the composite material is higher, the resistance change amplitude is significantly increased, and the sensitivity is improved accordingly; at the same time, the composite material can also provide rich adsorption sites through the chemical sensitization effect. The high oxygen vacancy concentration of the composite material also promotes the chemical adsorption of hydrogen sulfide molecules, which is beneficial to improving the performance of the sensor.

[0014] 3. The hydrogen sulfide sensor prepared by the present invention achieves a high sensitivity response to low concentration hydrogen sulfide at 200°C (S Ra / Rg =39@0.5 ppm), with a response time of only 6 seconds and a recovery time of 153 s, an ultra-low detection limit as low as 20 ppb, and excellent hydrogen sulfide selectivity (S H2S / S NH3 = ~181, S H2S / S H2 = ~214). In addition, the sensor of the present invention still exhibits a good response characteristic of 10 to 0.5 ppm hydrogen sulfide at a low temperature of 50°C, achieving effective detection of low-concentration hydrogen sulfide at low temperatures.

[0015] 4. Compared with traditional noble metal-modified semiconductor metal oxide hydrogen sulfide sensors, the sensor of the present invention greatly reduces costs; and the process of the present invention is compatible with rigid and flexible substrates, which is conducive to adapting to microelectronic processes and provides a reliable technical foundation for the future development of integrated, miniaturized and intelligent hydrogen sulfide sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the XRD spectrum of the SnO2@CuO composite material in the embodiment of the present invention; Figure 2 (a) is a scanning electron microscope (SEM) surface photograph of the SnO2@CuO composite material in an embodiment of the present invention; (b) is a transmission electron microscope (TEM) photograph of the SnO2@CuO composite material; Figure 3 XPS spectra of the 80-cycle SnO2@CuO composite material in the embodiment of the present invention: (a) Sn 3d, (b) Cu 2p, (c) O 1s; Figure 4 Gas sensing performance of the SnO2@CuO hydrogen sulfide sensor for 0.5 ppm H2S over 80 cycles in an embodiment of the present invention: (a) Sensitivity versus time curve at different temperatures; (b) Effect of operating temperature on sensor sensitivity and response / recovery time; (c) Response and recovery time of the sensor at 200°C; (d) Repeatability curve. Figure 5 Other gas-sensing properties of the SnO2@CuO hydrogen sulfide sensor of the present invention after 80 cycles at 200°C: (a) sensitivity variation with time for different H2S concentrations; (b) selectivity test; (c) effect of relative humidity on sensor sensitivity; (d) long-term stability test; (e) sensitivity variation with time at different low operating temperatures; (f) effect of low operating temperature on sensor sensitivity and response / recovery time.

[0017] Figure 6 This is the sensitivity curve of the CuO hydrogen sulfide sensor to 0.5 ppm H2S at 275°C in Comparative Example 1 over time. DETAILED DESCRIPTION Example 1

[0018] A semiconductor metal oxide-based composite hydrogen sulfide sensor comprises a SiO2 / Si substrate, a SnO2@CuO composite gas-sensitive layer, and a Pt interdigital electrode.

[0019] The method for preparing the above-mentioned sensor comprises the following steps: (1) Select SiO2 / Si as the substrate of the sensor, place it on the cleaning rack, then place the cleaning rack in a beaker, and then use acetone, isopropyl alcohol, anhydrous ethanol, and deionized water to perform ultrasonic cleaning for 5 minutes respectively. Finally, blow the cleaned SiO2 / Si substrate dry with high-purity nitrogen (99.999%) and set aside.

[0020] (2) CuO powder was synthesized by hydrothermal method. The specific process was as follows: 2.14 g Cu(CH3COO)2·H2O was dissolved in 40 mL deionized water, 13.64 ml NH3·H2O was slowly added, and magnetic stirring was performed; then 0.71 g NaOH was added and stirring was continued for 30 minutes. The mixed solution was poured into a reactor and heated at 180 °C. After the powder was obtained, it was washed three times with ethanol and deionized water respectively, and then dried to obtain CuO powder.

[0021] (3) Based on step (2), 80 cycles of SnO2 thin film were deposited on CuO powder using ALD technology. The deposition temperature was 120 °C. The precursor sources used were tetrakis(dimethylamino)tin (TDMSn) and water (H2O). The pulse and cleaning times of tetrakis(dimethylamino)tin (TDMSn) and water (H2O) were 0.2 s and 6.0 s, respectively.

[0022] (4) Based on step (3), 80 cycles of SnO2@CuO were dissolved in ethanol solution and uniformly coated on the SiO2 / Si substrate prepared in step (1) by drop coating.

[0023] (5) Place the interdigitated electrode mask close to the sample after step (4), and then use magnetron sputtering to sputter 100 nm thick metal platinum (Pt) as a conductive electrode. After wiring and packaging, it can be used as a sensitive element for detecting hydrogen sulfide.

[0024] Figure 1 Figure 3 is the XRD spectrum of the SnO2@CuO composite material. The characteristic peaks of CuO powder can be observed, which is consistent with the standard spectrum of CuO monoclinic system (PDF#45-0937). However, the diffraction peaks of SnO2 film do not appear, indicating that SnO2 exists in an amorphous form.

[0025] Figure 2 These are scanning electron microscope (SEM) and transmission electron microscope (TEM) photos of the SnO2@CuO composite material. It can be seen from the figure that the SnO2@CuO composite material has a nanosheet structure, and the surface of CuO is evenly covered with a layer of amorphous SnO2 thin film with a thickness of about 2 nm.

[0026] Figure 3The XPS spectrum of the SnO2@CuO composite material after 80 cycles in the embodiment of the present invention shows that Sn and Cu elements are Sn 4+ and Cu 2+ The asymmetric peak of O1s can be decomposed into lattice oxygen, oxygen vacancies and adsorbed oxygen, among which the concentration of oxygen vacancies is as high as 31.9%, indicating that SnO2@CuO composites have higher potential in hydrogen sulfide detection.

[0027] Figure 4 Figure 3 shows the gas-sensing performance of the 80-cycle SnO2@CuO hydrogen sulfide sensor for 0.5 ppm H2S in an embodiment of the present invention. The figure shows that the 80-cycle SnO2@CuO hydrogen sulfide sensor exhibits optimal performance for 0.5 ppm hydrogen sulfide at 200°C, with a sensitivity of 39, a response time of only 6 seconds, a recovery time of 153 s, and good repeatability.

[0028] Figure 5 Figure 2 shows other gas-sensing properties of the SnO2@CuO hydrogen sulfide sensor after 80 cycles at 200°C in the embodiment of the present invention. It can be seen that the sensor exhibits excellent performance for hydrogen sulfide at 200°C, including a wide range of 20 ppb-10 ppm and an ultra-low detection limit as low as 20 ppb, ultra-high sensitivity (934) and ultra-fast response (<2s) to 10 ppm hydrogen sulfide, excellent selectivity, good moisture resistance and long-term stability. In addition, the sample has excellent detection capability for hydrogen sulfide at low temperatures, and still maintains a high response value (10) for 0.5 ppm hydrogen sulfide at a low temperature of 50°C, and the response / recovery time is 91 / 390s, respectively.

[0029] Comparative Example 1 A hydrogen sulfide sensor was prepared by using CuO synthesized by the same hydrothermal method as in Example 1 as a gas-sensitive material.

[0030] Figure 6 The sensitivity curve of the CuO hydrogen sulfide sensor to 0.5 ppm H2S at 275°C changes with time. It can be seen that only the hydrogen sulfide sensor prepared by hydrothermal synthesis of single CuO has a high operating temperature, and its sensitivity is much lower than that of the SnO2@CuO composite gas-sensitive material hydrogen sulfide sensor in Example 1, indicating the superior performance of the SnO2@CuO composite gas-sensitive material hydrogen sulfide sensor in the present invention. Example 2

[0031] A semiconductor metal oxide-based composite hydrogen sulfide sensor comprises a quartz glass substrate, a SnO2@CuO composite gas-sensitive layer, and Al interdigital electrodes.

[0032] The method for preparing the above-mentioned sensor comprises the following steps: (1) Select quartz glass as the substrate of the sensor, place it on the cleaning rack, then place the cleaning rack in a beaker, and then use acetone, isopropyl alcohol, anhydrous ethanol, and deionized water to perform ultrasonic cleaning for 5 minutes respectively. Finally, blow the cleaned SiO2 / Si substrate dry with high-purity nitrogen (99.999%) and set aside.

[0033] (2) CuO powder was synthesized by a hydrothermal method. The specific process was as follows: 1.5 g of Cu(CH3COO)2·H2O was dissolved in 20 mL of deionized water, 5 ml of NH3·H2O was slowly added, and magnetic stirring was performed. Subsequently, 0.4 g of NaOH was added and stirring was continued for 20 minutes. The mixed solution was poured into a reactor and heated at 150°C. After the powder was obtained, it was washed twice with ethanol and deionized water, and then dried to obtain CuO powder.

[0034] (3) Based on step (2), ALD technology was used to deposit 160 cycles of SnO2 thin film on CuO powder. The deposition temperature was 50 °C. The precursor sources used were SnCl4 and water (H2O), and the pulse and cleaning times of SnCl4 and water (H2O) were 0.2 s and 6.0 s, respectively.

[0035] (4) Based on step (3), 160 cycles of SnO2@CuO were dissolved in ethanol solution and uniformly coated on the quartz glass substrate prepared in step (1) by drop coating.

[0036] (5) Place the interdigitated electrode mask close to the sample after step (4), and then use magnetron sputtering to sputter 200 nm thick metal aluminum (Al) as a conductive electrode. After wiring and packaging, it can be used as a sensitive element for detecting hydrogen sulfide. Example 3

[0037] A composite thin film humidity sensor based on ternary semiconductor metal oxide includes: a mica substrate, a SnO2@CuO composite material gas-sensitive layer, and Au interdigital electrodes.

[0038] The method for preparing the humidity sensor comprises the following steps: (1) Select mica as the substrate of the sensor, place it on the cleaning rack, then place the cleaning rack in a beaker, and then use acetone, isopropyl alcohol, anhydrous ethanol, and deionized water to ultrasonically clean it for 5 minutes respectively. Finally, blow the cleaned mica substrate dry with high-purity nitrogen (99.999%) and set aside; (2) CuO powder was synthesized using a hydrothermal method. The specific process was as follows: 2.5 g of Cu(CH3COO)2·H2O was dissolved in 45 mL of deionized water, 15 ml of NH3·H2O was slowly added, and magnetic stirring was performed. Subsequently, 1.35 g of NaOH was added and stirring was continued for 40 minutes. The mixed solution was poured into a reactor and heated at 170°C. After obtaining a powder, it was washed four times with ethanol and four times with deionized water. After drying, CuO powder was obtained.

[0039] (3) Based on step (2), 20 cycles of SnO2 thin film were deposited on CuO powder using ALD technology. The deposition temperature was 200 °C. The precursor sources used were SnCl4 and ozone. The pulse and cleaning times of SnCl4 and ozone were 0.1 s and 5.0 s, respectively.

[0040] (4) Based on step (3), 20 cycles of SnO2@CuO were dissolved in ethanol solution and uniformly coated on the mica substrate prepared in step (1) by drop coating.

[0041] (5) Place the interdigitated electrode mask close to the sample after step (4), and then use magnetron sputtering to sputter 150 nm thick gold (Au) as a conductive electrode. After wiring and packaging, it can be used as a sensitive element for detecting hydrogen sulfide. Example 4

[0042] A composite thin film humidity sensor based on ternary semiconductor metal oxide includes: a polyimide (PI) substrate, a SnO2@CuO composite material gas-sensitive layer, and Ag interdigital electrodes.

[0043] The method for preparing the humidity sensor comprises the following steps: (1) Select PI as the substrate of the sensor, place it on the cleaning rack, then place the cleaning rack in a beaker, and then use acetone, isopropyl alcohol, anhydrous ethanol, and deionized water to ultrasonically clean it for 5 minutes respectively. Finally, blow the cleaned PI substrate dry with high-purity nitrogen (99.999%) and set aside; (2) CuO powder was synthesized using a hydrothermal method. The specific process was as follows: 3.12 g of Cu(CH3COO)2·H2O was dissolved in 50 mL of deionized water, 18 ml of NH3·H2O was slowly added, and magnetic stirring was performed. Subsequently, 1.65 g of NaOH was added and stirring was continued for 50 minutes. The mixed solution was poured into a reactor and heated at 190°C. After obtaining a powder, it was washed four times with ethanol and four times with deionized water. After drying, CuO powder was obtained.

[0044] (3) Based on step (2), SnO2 thin films were deposited on CuO powder by PEALD for 200 cycles. The deposition temperature was room temperature. The precursor sources used were SnCl4 and plasma oxygen. The pulse time and cleaning time of SnCl4 were 0.6 s and 15 s, respectively. The pulse time and cleaning time of plasma oxygen were 30 s and 25 s, respectively. (4) Based on step (3), 200 cycles of SnO2@CuO were dissolved in ethanol solution and evenly coated on the PI substrate prepared in step (1) by drop coating.

[0045] (5) Place the interdigitated electrode mask close to the sample after step (4), and then use magnetron sputtering to sputter 150 nm thick silver (Ag) as a conductive electrode. After wiring and packaging, it can be used as a sensitive element for detecting hydrogen sulfide. Example 5

[0046] A composite thin film humidity sensor based on ternary semiconductor metal oxide includes: a polyethylene terephthalate (PET) substrate, a SnO2@CuO composite material gas-sensitive layer, and a Pt interdigital electrode.

[0047] The method for preparing the humidity sensor comprises the following steps: (1) Select PET as the substrate of the sensor, place it on the cleaning rack, then place the cleaning rack in a beaker, and then use acetone, isopropyl alcohol, anhydrous ethanol, and deionized water to ultrasonically clean it for 5 minutes respectively. Finally, blow the cleaned PET substrate dry with high-purity nitrogen (99.999%) and set aside; (2) CuO powder was synthesized using a hydrothermal method. The specific process was as follows: 3.5 g of Cu(CH3COO)2·H2O was dissolved in 60 mL of deionized water, 20 ml of NH3·H2O was slowly added, and magnetic stirring was applied. Subsequently, 1.8 g of NaOH was added and stirring was continued for 60 minutes. The mixed solution was poured into a reactor and heated at 200°C. After obtaining a powder, it was washed with ethanol and deionized water five times each and dried to obtain CuO powder.

[0048] (3) Based on step (2), SnO2 thin films were deposited on CuO powder by PEALD for 60 cycles. The deposition temperature was 50 °C. The precursor sources used were SnCl4 and plasma oxygen. The pulse time and cleaning time of SnCl4 were 0.3 s and 12 s, respectively. The pulse time and cleaning time of plasma oxygen were 30 s and 25 s, respectively. (4) Based on step (3), 60 cycles of SnO2@CuO were dissolved in ethanol solution and evenly coated on the PET substrate prepared in step (1) by drop coating.

[0049] (5) Place the interdigitated electrode mask close to the sample after step (4), and then use magnetron sputtering to sputter 100 nm thick metal platinum (Pt) as a conductive electrode. After wiring and packaging, it can be used as a sensitive element for detecting hydrogen sulfide.

[0050] The above are merely preferred embodiments of the present invention, which will help those skilled in the art further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that any modifications and improvements made by those skilled in the art without departing from the scope of the present invention are within the scope of protection of the present invention.

Claims

1. A method for preparing a composite gas-sensitive material based on semiconductor metal oxide, characterized in that: The following steps are involved: (1) Synthesis of CuO powder with nanosheet structure; (2) SnO2 thin film was deposited on the synthesized CuO powder by ALD technology to obtain SnO2@CuO composite gas-sensitive material.

2. The method for preparing a composite gas-sensitive material based on semiconductor metal oxide according to claim 1, characterized in that: CuO powder with nanosheet structure was synthesized by hydrothermal method.

3. The method for preparing a composite gas-sensitive material based on semiconductor metal oxide according to claim 2, characterized in that: The hydrothermal method for synthesizing CuO powder with a nanosheet structure specifically includes the following steps: dissolving 1.5-3.5 g of Cu(CH3COO)2·H2O in 20-60 mL of deionized water, slowly adding 5-20 ml of NH3·H2O, and stirring; then adding 0.4-1.8 g of NaOH, continuing to stir for 20-60 minutes, pouring the mixed solution into a reactor and heating it at 150-200°C to obtain powder, washing it with ethanol and deionized water 2-5 times each, and then drying it to obtain CuO powder.

4. The method for preparing a composite gas-sensitive material based on semiconductor metal oxide according to claim 1, characterized in that: The parameters for depositing SnO2 thin films using ALD technology are set as follows: deposition temperature is room temperature-200℃, source temperature of the tin source is 60℃-100℃, pulse and cleaning time of the tin source are 0.1 s-0.6 s and 6.0 s-15 s respectively, pulse and cleaning time of the oxygen source are: 0.1 s-30 s, 5 s-25 s, gas flow rate is 150 sccm, and the number of cycles is 20-200 cycles.

5. The method for preparing a composite gas-sensitive material based on semiconductor metal oxide according to claim 1 or 4, characterized in that: The tin source used in ALD deposition is tetrakis(dimethylamino)tin or SnCl4, and the oxygen source is water, ozone or plasma oxygen.

6. A composite gas-sensitive material based on semiconductor metal oxide, characterized in that: The composite gas-sensitive material is a SnO2@CuO composite material formed by SnO2 thin film coating CuO powder with a nanosheet structure.

7. Use of the semiconductor metal oxide-based composite gas-sensitive material according to claim 6 in a hydrogen sulfide sensor, characterized in that: The composite gas-sensitive material is used for the gas-sensitive layer of a hydrogen sulfide sensor.

8. Use of the semiconductor metal oxide-based composite gas-sensitive material in a hydrogen sulfide sensor according to claim 7, characterized in that: The hydrogen sulfide sensor comprises, from bottom to top, an insulating substrate, a semiconductor metal oxide composite gas-sensitive layer, and a conductive electrode layer; the semiconductor metal oxide composite gas-sensitive layer is a SnO2@CuO composite material formed by SnO2 thin film coated with CuO powder with a nanosheet structure.

9. Use of the semiconductor metal oxide-based composite gas-sensitive material according to claim 7 or 8 in a hydrogen sulfide sensor, characterized in that: The preparation of the hydrogen sulfide sensor comprises the following steps: (1) Treat the insulating substrate and keep it ready for use; (2) dissolving the SnO2@CuO composite gas-sensitive material powder in an ethanol solution and uniformly coating the powder on the treated insulating substrate by a drop coating method to form a SnO2@CuO composite gas-sensitive layer; (3) Using a mask, metal interdigital electrodes are deposited on the SnO2@CuO composite material gas-sensitive layer as conductive electrodes, and after wiring and packaging, a SnO2@CuO composite material hydrogen sulfide sensor can be obtained.

10. Use of the semiconductor metal oxide-based composite gas-sensitive material according to claim 9 in a hydrogen sulfide sensor, characterized in that: The insulating substrate is an inorganic substrate or a polymer substrate.

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