A H2S gas sensor thin film material for vacuum environment and its preparation method

Abstract

The present invention relates to the field of gas sensor technology and proposes a H2S gas sensor thin film material for use in vacuum environments and a method for preparing the same. The thin film material is a SnO2-CuO or ZnO-CuO composite material. The Cu ion-doped SnO2-CuO and ZnO-CuO composite films prepared by the present invention have an oxygen-independent reaction between CuO and H2S; CuO can directly react with H2S to form CuS, enabling efficient H2S gas detection under vacuum conditions. This mechanism makes the sensor particularly suitable for applications such as spacecraft and deep space exploration, where gas detection under low oxygen or vacuum conditions is required.

Description

Technical Field

[0001] The present invention relates to the technical field of gas sensors, and in particular to an H2S gas sensor thin film material for a vacuum environment and a preparation method thereof. Background Art

[0002] Existing gas sensors, primarily based on metal oxide semiconductor (MOS) materials, are widely used in environmental monitoring, industrial safety, and health diagnostics. MOS sensors excel in H2S detection due to their simple structure, low cost, and high gas sensitivity.

[0003] However, most traditional MOS sensors rely on atmospheric oxygen for gas adsorption and reaction. Their performance degrades significantly in vacuum or oxygen-deficient environments, making them difficult to operate effectively under extreme conditions such as deep space exploration. For example, when existing sensors detect H2S gas in low-pressure environments, their detection sensitivity decreases with changes in oxygen content. These sensors primarily operate at room temperature, atmospheric pressure, or high temperatures, relying on changes in surface oxygen adsorption and exhibiting a certain degree of recovery. Furthermore, metal oxide semiconductor materials experience reduced carrier concentration and electron mobility at low temperatures, resulting in decreased detection sensitivity. Therefore, a highly efficient gas sensor suitable for vacuum conditions is urgently needed. Summary of the Invention

[0004] In view of this, the present invention proposes a thin film material for a high-efficiency gas sensor suitable for vacuum conditions and a preparation method thereof.

[0005] The technical solution of the present invention is implemented as follows: In a first aspect, the present invention provides a thin film material for an H2S gas sensor for use in a vacuum environment, wherein the thin film material is a SnO2-CuO or ZnO-CuO composite material.

[0006] Traditional metal oxide gas sensors (such as pure SnO2 or ZnO) perform well in atmospheric environments, primarily because gas adsorption and reaction rely on oxygen. Oxygen adsorbs on the material surface, forming adsorbed oxygen. This oxygen reacts with the target gas (such as H2S), causing a change in the depletion layer thickness and a resulting resistance change. However, in vacuum or low oxygen conditions, the surface adsorbed oxygen decreases as the vacuum level increases, severely impacting sensing performance.

[0007] The Cu-ion-doped SnO2-CuO and ZnO-CuO thin films prepared by this invention exhibit an oxygen-independent reaction between CuO and H2S. CuO reacts directly with H2S to form CuS, enabling efficient H2S gas detection under vacuum conditions. This mechanism makes the sensor particularly suitable for applications requiring gas detection in low-oxygen or vacuum conditions, such as spacecraft and deep space exploration.

[0008] On the basis of the above technical solution, preferably, the atomic ratio of Cu / Sn in the thin film material SnO2-CuO is 0.03-0.09:1, and the atomic ratio of Cu / Zn in the thin film material ZnO-CuO is 0.001-0.007:1.

[0009] In a second aspect, the present invention provides a method for preparing a thin film material for an H2S gas sensor for use in a vacuum environment, comprising the following steps:

[0010] S1, adding ethanol, water, zinc acetate or tin acetate into a reaction kettle and stirring uniformly as a base solvent; then adding copper acetate and stirring the mixed solution until the solution is transparent and uniform;

[0011] S2, adding an alkaline reagent to adjust the pH of the mixed solution to 8-9, and then heating the mixed solution at 50-70° C. with stirring for 1-2 hours to form a sol;

[0012] S3, coating the sol on a substrate by spin coating technology, drying and calcining to obtain a SnO2-CuO or ZnO-CuO thin film.

[0013] On the basis of the above technical solution, preferably, during the calcination in step S3, the substrate coated with the thin film is placed in an air atmosphere, kept at 400° C. to 600° C. for 1 to 2 hours, and then cooled.

[0014] On the basis of the above technical solution, preferably, in step S3, the coating rate is 2500-3000 rpm, the time is 20-30 s, and the thickness is 500-700 nm.

[0015] In a third aspect, the present invention provides an H2S gas sensor for use in a vacuum environment, wherein the sensor uses SnO2-CuO or ZnO-CuO thin film material as a gas-sensitive material.

[0016] In a fourth aspect, the present invention provides a method for detecting H2S gas using a sensor, comprising the following steps:

[0017] S1, placing the sensor in a sealed cavity with a UV-LED, and irradiating the surface of the SnO2-CuO or ZnO-CuO film with the UV-LED;

[0018] S2, the chamber is evacuated to 10 -3 Pa, and then inject H2S gas, and detect H2S gas under vacuum conditions.

[0019] UV light irradiation provides additional energy, accelerating the reaction between CuO and H2S. This energy excitation can increase the reaction rate and sensor sensitivity. The role of UV light is particularly important under vacuum conditions, as it compensates for the poor reaction kinetics caused by the lack of oxygen.

[0020] On the basis of the above technical solution, preferably, the wavelength of the UV-LED is 360-365 nm, and the power is 2600-2900 mW.

[0021] Based on the above technical solution, preferably, the distance between the UV-LED and the thin film material is ≤5 cm.

[0022] The H2S gas sensor thin film material for vacuum environment and the preparation method thereof of the present invention have the following beneficial effects compared with the prior art:

[0023] (1) In the SnO2-CuO and ZnO-CuO thin film materials prepared by the present invention, the reaction between CuO and H2S is independent of oxygen, and CuS can be directly generated by the reaction. This enables the sensor to achieve efficient H2S gas detection under vacuum conditions. This mechanism makes the sensor particularly suitable for applications such as spacecraft and deep space exploration that require gas detection under low oxygen or vacuum conditions.

[0024] (2) Under vacuum conditions, the sensor uses UV light to excite the carriers in SnO2-CuO and ZnO-CuO materials, increasing their surface energy states, thereby effectively improving the adsorption capacity of H2S gas and increasing the sensitivity of the sensor.

[0025] (3) The present invention uses SnO2-CuO and ZnO-CuO thin film materials as the gas-sensitive materials of the sensor, so that the sensor has a pn heterostructure, which can enhance the separation of electrons and holes, promote the efficient progress of surface reactions, and thus improve the sensitivity, response speed and detection limit of the gas sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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.

[0027] Figure 1 This is the gas sensing performance test diagram of CuO-ZnO thin film gas sensors with different copper contents;

[0028] Figure 2 The response curve of the ZnO-CuO thin film sensor with a copper content of 0.7% when injected with different concentrations of H2S;

[0029] Figure 3SEM images of CuO-ZnO thin films, a is a low magnification SEM image, b is a high magnification SEM image, and c is a cross-sectional SEM image of the film;

[0030] Figure 4 is the EDS image of CuO-ZnO film, a is the EDS image of CuO-ZnO film, b is the EDS spectrum of CuO-ZnO film, c~e are the element distribution maps of O, Cu and Zn respectively;

[0031] Figure 5 This is the gas sensing performance test diagram of SnO2-CuO thin film gas sensor with different copper contents;

[0032] Figure 6 The response curve of SnO2-CuO thin film sensor with 9% copper content injected with different concentrations of H2S;

[0033] Figure 7 SEM images of SnO2-CuO thin films, a is the front image, b is the cross-sectional image;

[0034] Figure 8 is the EDS image of SnO2-CuO film, a is the EDS image of CuO-SnO2 film, b is the EDS spectrum of CuO-SnO2 film, c~e correspond to the distribution of O, Cu, Sn elements in the film respectively;

[0035] Figure 9 The response curve of ZnO-CuO thin film gas sensor with copper content of 0.7% at different annealing temperatures to H2S;

[0036] Figure 10 The graph shows the resistance change curve of SnO2-CuO thin film gas sensor with 9% copper content at different annealing temperatures to H2S;

[0037] Figure 11 For 3×10 -3 Changes in resistance of SnO2-CuO and ZnO-CuO sensors over time under UV LED irradiation under Pa vacuum conditions; a is the selectivity of SnO2-CuO and ZnO-CuO sensors to different gases (CO, NO2, H2, H2S) at 10 ppm, b is the change in sensor sensitivity with H2S concentration (0-25 ppm), and c is the detection limit of the sensor;

[0038] Figure 12 PL photoluminescence spectra of pure ZnO and CuO-ZnO thin films;

[0039] Figure 13 PL photoluminescence spectra of pure SnO2 and SnO2-CuO thin films;

[0040] Figure 14 For display in 3×10 -3 Under Pa vacuum conditions, the resistance of SnO2-CuO (Figure a) and ZnO-CuO (Figure b) sensors changes with time in the dark and under UV (365nm) LED irradiation;

[0041] Figure 15 This is the internal structure diagram of the sensor;

[0042] Figure 16 This is a performance comparison chart of Ag2O-SnO2 and SnO2-CuO. DETAILED DESCRIPTION

[0043] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] The present invention provides a gas sensor for detecting H2S gas in a vacuum environment. The gas sensor uses SnO2-CuO and ZnO-CuO thin films as gas-sensitive materials. The gas sensor of the present invention is different from existing gas sensors in that an ultraviolet lamp is provided inside the cavity for irradiating the SnO2-CuO and ZnO-CuO thin films, and the distance between the ultraviolet lamp and the SnO2-CuO and ZnO-CuO thin film materials is ≤5 cm (see Figure 15 ).

[0045] As shown in the figure, the gas sensor of the present invention is located in a closed cavity. A mechanical pump / molecular pump, a source meter, an ionization gauge / resistance gauge and a gas injection device are provided on the top of the cavity. The gas injection device is used to inject the H2S gas to be detected; the mechanical pump / molecular pump is a vacuum device used to extract the air in the cavity to maintain a vacuum state; the ionization gauge / resistance gauge is used to detect the vacuum degree in the cavity, the resistance gauge is used to detect low vacuum, and the ionization gauge is used to detect high vacuum; the source meter provides power support for the gas sensor and ultraviolet lamp.

[0046] Example 1

[0047] The preparation method of the ZnO-CuO thin film material for the H2S gas sensor used in a vacuum environment in this embodiment is as follows:

[0048] S1. Add 0.01 mol zinc acetate (Zn(CH3COO)2·2H2O) to 50 mL of 75% ethanol aqueous solution prepared from anhydrous ethanol and deionized water, heat and stir at 75°C to dissolve it as a base solvent.

[0049] S2, adding copper acetate (Cu(CH3COO)2·H2O) to the solution of step S1 according to a set doping ratio of Cu / Zn atomic ratio (molar ratio) of 0.001 to 0.009:1, and stirring the mixed solution until it becomes transparent to obtain a precursor solution.

[0050] In step S3, to improve stability, an alkaline agent, sodium hydroxide (NaOH), was added to the precursor solution to adjust the pH value of the solution to 8. The solution was then heated and stirred at 60° C. for 1 h to form a uniform sol.

[0051] S4, the prepared sol is coated on the substrate (interdigitated electrode) by spin coating technology, the spin coating rate is set to 3000 rpm, the duration is 20 seconds, and the thickness is 645 nm.

[0052] S5. After coating, the substrate (interdigitated electrode) is placed in an oven and dried at 100° C. for 30 minutes to remove the solvent, and then calcined at 450° C. for 2 hours to obtain a ZnO-CuO thin film.

[0053] ZnO-CuO films doped with different Cu contents were used as gas-sensitive materials to prepare gas sensors. Gas detection experiments were carried out to evaluate their response performance in H2S gas.

[0054] The detection method is as follows: a ZnO-CuO thin film gas sensor is placed in a sealed cavity, a UV-LED is set in the cavity, the distance between the UV-LED and the thin film material is ≤5cm, and the UV-LED irradiates the surface of the ZnO-CuO thin film, the UV-LED wavelength is 360nm, and the power is 2900mW; the cavity is evacuated to 10 -3 Pa, and then inject H2S gas, and detect H2S gas under vacuum conditions.

[0055] pass Figure 1 Analysis of the curves reveals that the response values ​​of the ZnO-CuO thin film gas sensor to 7.5 ppm H2S are 2.63, 3.86, 5.96, 7.51, and 11.63, respectively. When the copper content does not exceed 0.7%, the response increases with increasing copper content. However, when the copper content increases from 0.7% (atomic ratio of 0.007:1) to 0.9% (atomic ratio of 0.007:1), the response decreases slightly. This indicates that the sensor reaches its highest sensitivity to H2S when the copper content in the film is 0.7%. This is likely because the number of heterojunctions in the film increases with increasing copper content, preventing further reduction in the sensor's resistance.

[0056] Figure 2The response of ZnO-CuO thin film gas sensor with 0.7% copper content was measured with the change of H2S gas concentration. The test method was as follows: at room temperature (25℃), vacuum (10 -3 The sensor's response curves for different gas concentrations under conditions of 100 nm (1000 ppm) and UV light (360 nm) irradiation are shown in the figure. The sensor's response values ​​for H2S gas at concentrations of 2.5 ppm, 5 ppm, 10 ppm, 15 ppm, 20 ppm, and 25 ppm are 5.03, 8.02, 15.05, 21.03, 28.18, and 45.75, respectively. This indicates that the sensor's response increases with increasing H2S concentration.

[0057] The microstructure, main element composition and ratio of ZnO-CuO composite films were characterized by field emission scanning electron microscopy (SEM). Figure 3 Figure (a) shows a frontal image of the ZnO-CuO nanofilm at a magnification of 27,000 times, showing the film's relatively rough surface. Further magnification to 112,000 times reveals that the film is composed of a stack of nanoparticles with a relatively uniform morphology and an average particle size between 30 and 50 nm, as shown in Figure (b). To determine the approximate thickness of the film, a cross-sectional image of the CuO-ZnO film was taken, as shown in Figure (c). It is clearly evident that the film's thickness is approximately 645 nm.

[0058] Figure 4 EDS images of the ZnO-CuO film are shown. Figures (c-e) show the uniform distribution of O, Cu, and Zn in the film. The EDS spectrum in Figure (b) can be used to examine the elemental composition and ratio of the film. The Cu:Zn ratio is 0.48 / 54.88 = 0.0087, which is roughly consistent with the nominal ratio of 0.009.

[0059] Example 2

[0060] The preparation method of SnO2-CuO thin film material for H2S gas sensor used in vacuum environment in this embodiment is as follows:

[0061] S1. Add 0.01 mol of tin acetate (Sn(CH3COO)2) to 50 mL of 75% ethanol aqueous solution prepared from anhydrous ethanol and deionized water, heat and stir at 75°C to dissolve it as a base solvent for later use.

[0062] S2, adding copper acetate (Cu(CH3COO)2·H2O) to the solution of step S1 according to a set doping ratio of Cu / Sn atomic ratio (molar ratio) of 0.03 to 0.12:1, and stirring the mixed solution until it becomes transparent to obtain a precursor solution.

[0063] In step S3, to improve stability, an alkaline agent, monoethanolamine (C2H7NO), was added to the precursor solution to adjust the pH value of the solution to 9. The solution was then heated and stirred at 70°C for 1 h to form a uniform sol.

[0064] S4, the prepared sol is coated on a substrate such as glass or silicon wafer using a spin coating technique, with the spin coating rate set to 2000 rpm, the duration being 30 seconds, and the thickness being 640 nm.

[0065] S5, after coating, the substrate is placed in an oven and dried at 100° C. for 30 minutes to remove the solvent, and then calcined at 450° C. for 2 hours to obtain a SnO2-CuO thin film.

[0066] SnO2-CuO films doped with different Cu contents were used as gas-sensitive materials to prepare gas sensors. Gas detection experiments were carried out to evaluate their response performance in H2S gas.

[0067] The detection method is as follows: the SnO2-CuO sensor is placed in a sealed cavity, a UV-LED is set in the cavity, the distance between the UV-LED and the film material is ≤5cm, and the UV-LED irradiates the surface of the SnO2-CuO film, the UV-LED wavelength is 365nm, and the power is 2600mW; the cavity is evacuated to 10 -3 Pa, and then inject H2S gas, and detect H2S gas under vacuum conditions.

[0068] Figure 5 As can be seen, the pure SnO2 sensor is almost insensitive to H2S, while sensors with copper contents of 3%, 6%, 9%, and 12% exhibited response values ​​of 39, 623, 2403, and 2268 to 15 ppm H2S, respectively. Similarly, the sensor response increases with increasing copper content. However, when the Cu content increases from 9% to 12%, the sensor response does not continue to increase, but instead decreases slightly. This is because after reacting with the injected H2S gas, numerous heterojunctions remain in the SnO2-CuO film, limiting further reduction in the sensor's resistance. In other words, with increasing copper content, the sensor sensitivity initially increases and then decreases. The sensor's sensitivity to H2S reaches its highest level when the copper content is 9%.

[0069] Figure 6 The SnO2-CuO thin film gas sensor with 9% copper content was studied at room temperature (25℃) and vacuum (10 -3The sensor's gas-sensing performance to various H2S gas concentrations under irradiation with ultraviolet light (365 nm) and a wavelength of 100 nm was measured. The test results were plotted as a response-time curve. As shown in the figure, the sensor exhibited varying degrees of response after injection of H2S gas at varying concentrations. The corresponding sensor responses to injections of 1 ppm, 2 ppm, 5 ppm, 15 ppm, and 25 ppm were 83.2, 117.4, 650, 2469, and 9799, respectively, indicating that the sensor's response increased with increasing H2S concentration.

[0070] The microstructure and elemental composition of SnO2-CuO thin films were observed by field emission scanning electron microscopy (SEM). Figure 7 Image (a) is a frontal image of a SnO2-CuO film magnified 100,000 times. The image shows that the film is composed of many tightly stacked small nanoparticles, including small particles with diameters between 10-20nm and some larger particles with diameters between 30-50nm. Image (b) shows a cross-sectional view of the SnO2-CuO film, from which it can be seen that the film thickness is approximately 0.64μm.

[0071] Figure 8 Shown are EDS images of a SnO2-CuO film doped with 0.09% copper. The information from the EDS spectrum in Figure (b) can be used to examine the elemental composition and ratios of the film. The calculated atomic ratio of Cu to Sn is 2.47 / 25.01 = 0.098, which is consistent with the nominal Cu ratio (9%) in heterojunction films. Figures (c-e) demonstrate the uniform distribution of O, Cu, and Sn throughout the film.

[0072] Test 1: The effect of different heat treatment temperatures on the sensor

[0073] Calcination temperature affects the growth of CuO grains. The higher the temperature, the more CuO is formed, which is more conducive to the reaction with H2S, which is consistent with the design idea. However, the higher the heating temperature is, the better the response effect is. Different ratios and temperatures have an impact on performance. Taking the 0.7% ZnO-CuO film prepared in Example 1 and the 9% SnO2-CuO film prepared in Example 2 as examples, the gas-sensing properties of the films at different heat treatment temperatures (450°C, 500°C, 550°C and 600°C) were tested respectively. The results are shown in Figure 2. Figure 9 and 10 .

[0074] By calculation, it can be concluded that the response values ​​of the gas sensor to 18ppm H2S gas are 2.7, 4.04, 26.6 and 12.1 for 0.7% ZnO-CuO films calcined at 450℃, 500℃, 550℃ and 600℃ respectively (see Figure 9The results show that sensors calcined at 450°C and 500°C exhibit lower response values ​​and lower slopes, indicating a slower response speed. Sensors calcined at 550°C and 600°C exhibit higher slopes and faster response speeds. The comparison shows that the response value of the sensor calcined at 550°C is higher than that of the sensor calcined at 600°C, indicating that sensors prepared at these temperatures have a higher sensitivity to H2S.

[0075] By calculation, it can be concluded that the response values ​​of the 9% SnO2-CuO thin films calcined at 450℃, 500℃, 550℃ and 600℃ to 5ppm H2S gas are 16.5, 41.6, 638 and 478 respectively (see Figure 10 Observing the response curves, we find that sensors heat-treated at 450°C and 500°C exhibit lower response values ​​and slower response speeds. In contrast, gas sensors calcined at 550°C and 600°C exhibit higher response values ​​and curve slopes. Further comparison reveals that the response value of the sensor calcined at 550°C is higher than that of the sensor calcined at 600°C, indicating that sensors heat-treated at this temperature have the highest sensitivity to H2S.

[0076] Test the detection sensitivity of the second sensor

[0077] Taking the 0.7% ZnO-CuO thin film gas sensor prepared in Example 1 and the 9% SnO2-CuO thin film gas sensor prepared in Example 2 as examples, the detection -3 Under Pa vacuum conditions, the selectivity of SnO2-CuO and ZnO-CuO sensors to different gases (CO, NO2, H2, H2S) at 10 ppm is shown in Figure 11 .

[0078] As shown in Figure a, the SnO2-CuO and ZnO-CuO thin-film gas sensors of the present invention can detect not only H2S but also CO, NO2, and H2 gases with high selectivity. As shown in Figure b, the responses of the SnO2-CuO and ZnO-CuO sensors to H2S increase with increasing H2S concentration (0-25 ppm), demonstrating their excellent sensitivity. As shown in Figure c, the detection limits of the SnO2-CuO and ZnO-CuO sensors are 100 ppb H2S.

[0079] Comparative Example 1

[0080] Comparative Example 1 uses a pure ZnO thin film. No copper acetate is added during the preparation of the ZnO thin film. The rest of the contents are the same as in Example 1.

[0081] The efficiency of photoinduced carrier separation in CuO / ZnO thin films was investigated using PL photospectroscopy. The principle of PL photospectroscopy is that light of a specific wavelength is irradiated onto the sample, exciting electrons in the valence band to transition to the conduction band, forming electron-hole pairs. After a certain period of time, the excited electrons return to the valence band and recombine with holes. This recombination process releases photons and emits fluorescence. The fluorescence intensity of these light at different wavelengths is measured using a spectrometer to generate the photoinduced spectrum.

[0082] The PL spectra of pure ZnO film and CuO-ZnO film with 0.7% copper content were tested at 365nm. Figure 12 shown.

[0083] Figure 12 It shows that pure ZnO film has higher fluorescence intensity than 0.7% CuO-ZnO film, which indicates that as the copper content of the film increases, the number of heterojunctions in the film also increases. Since the heterojunction can effectively separate photogenerated carriers and inhibit their recombination, this leads to lower fluorescence intensity.

[0084] Comparative Example 2

[0085] Comparative Example 2 uses a pure SnO2 film. No copper acetate is added during the preparation of the SnO2 film. The rest of the contents are the same as in Example 2.

[0086] PL photoluminescence spectra of pure SnO2 film and 9% SnO2-CuO film at 365nm. Figure 13 It can be observed that the pure SnO2 film has a higher PL intensity than the SnO2-CuO film, indicating a higher recombination rate of photogenerated electrons and holes. With the introduction of CuO, the PL intensity of the film decreases significantly, indicating that the recombination of photogenerated carriers is suppressed. This is attributed to the ability of the heterojunction formed in the film to efficiently separate photogenerated carriers, with photogenerated electrons and holes being separated into different regions of the heterojunction. These phenomena indicate the formation of a SnO2-CuO heterojunction.

[0087] Comparative Example 3

[0088] The sensors prepared with the 0.7% ZnO-CuO film prepared in Example 1 and the 9% SnO2-CuO film prepared in Example 2 as gas-sensitive materials were used to detect H2S gas under UV irradiation (365nm) and in the dark without UV irradiation. The results are shown in Table 1. Figure 14 .

[0089] Figure 14As shown in a and b, UV irradiation significantly improves the gas adsorption capacity and electron mobility on the surface of ZnO-CuO and SnO2-CuO materials, shortening the response time of ZnO-CuO and SnO2-CuO thin film gas sensors to H2S gas, thereby improving the detection accuracy.

[0090] Comparative Example 4

[0091] Comparative Example 4 is compared with Example 2, except that Ag2O replaces CuO to prepare 9% Ag2O-SnO2, and the rest of the contents are the same. Figure 16 .

[0092] Ag2O composite nanoparticles containing the same ratio (9%) were synthesized and reacted with 10 ppm H2S under light conditions. The reacted materials were then placed in air and heated at 100°C for 24 hours, and then measured and compared again.

[0093] Figure 16 It can be seen that the stability of Ag2O-SnO2 composite nanoparticles gradually decreases with time and finally loses its activity, while the performance of CuO composite materials remains basically unchanged, indicating that CuO has better stability than Ag2O.

[0094] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for detecting H2S gas using a sensor in a vacuum environment, characterized in that: The following steps are involved: S1, placing the sensor in a sealed cavity with a UV-LED, and irradiating the surface of the SnO2-CuO or ZnO-CuO film with the UV-LED; S2, the chamber is vacuumed to 10 -3 Pa, and then inject H2S gas, and detect H2S gas under vacuum conditions.

2. The method for detecting H2S gas using a sensor under a vacuum environment according to claim 1, wherein: The atomic ratio of Cu / Sn in the SnO2-CuO is 0.03-0.09:1, and the atomic ratio of Cu / Zn in the ZnO-CuO is 0.001-0.007:

1.

3. The method for detecting H2S gas using a sensor under a vacuum environment according to claim 1, wherein: The method for preparing the SnO2-CuO or ZnO-CuO thin film comprises the following steps: S1, adding ethanol, water, zinc acetate or tin acetate into a reaction kettle and stirring uniformly as a base solvent; then adding copper acetate and stirring the mixed solution until the solution is transparent and uniform; S2, adding an alkaline reagent to adjust the pH of the mixed solution to 8-9, and then heating the mixed solution at 50-70° C. and stirring for 1-2 hours to form a sol; S3, coating the sol on a substrate by spin coating technology, drying and calcining to obtain a SnO2-CuO or ZnO-CuO thin film.

4. The method for detecting H2S gas using a sensor under a vacuum environment according to claim 3, wherein: During the calcination in step S3, the substrate coated with the thin film is placed in an air atmosphere, kept at 400° C. to 600° C. for 1 to 2 hours, and then cooled.

5. The method for detecting H2S gas using a sensor under a vacuum environment according to claim 3, wherein: In step S3, the coating rate is 2500-3000 rpm, and the coating time is 20-30 s.

6. The method for detecting H2S gas using a sensor in a vacuum environment according to claim 3, wherein: The coating thickness in step S3 is 500 to 700 nm.

7. The method for detecting H2S gas using a sensor in a vacuum environment according to claim 1, wherein: The UV-LED has a wavelength of 360-365 nm and a power of 2600-2900 mW.

8. The method for detecting H2S gas using a sensor in a vacuum environment according to claim 1, wherein: The distance between UV-LED and film material is ≤5cm.

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