Pd-SA / WOS ternary composite gas sensitive material as well as preparation method and application thereof
By uniformly loading Pd single atoms onto the surface of the WS2/WO3 composite, a Pd-SA/WOS ternary composite gas-sensitive material was prepared, which solved the problems of high temperature, low selectivity and low catalytic efficiency of hydrogen sensors, and realized hydrogen detection with fast response at low temperature and high sensitivity.
Patent Information
- Application Number
- CN202511683116.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-17
- Publication Date
- 2026-02-10
AI Technical Summary
Existing hydrogen sensors suffer from problems such as high operating temperature, low selectivity, slow response speed, and low catalytic efficiency of precious metals. In particular, the low utilization rate of Pd nanoparticles limits the improvement of hydrogen sensing performance.
Pd single atoms were uniformly loaded onto the surface of the WS2/WO3 composite to form a Pd-SA/WOS ternary composite gas-sensitive material. WS2/WO3 nanoflower structures were prepared by hydrothermal and calcination methods, and Pd single atoms were loaded by impregnation method to optimize the morphology and band structure of the material.
The sensor's operating temperature was significantly reduced, the hydrogen response speed and selectivity were improved, the catalytic activity of the material was enhanced, and low-temperature rapid response and high-sensitivity hydrogen detection were achieved.
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Abstract
Description
Technical Field
[0001] This invention relates to a Pd-SA / WOS ternary composite gas-sensitive material, its preparation method, and its application, belonging to the field of semiconductor gas sensor technology. Background Technology
[0002] Hydrogen, as a clean energy source, can replace traditional fossil fuels and is widely used in industrial production, energy systems, aerospace, and other fields, fundamentally achieving the goal of "carbon reduction" and alleviating the increasingly serious environmental pollution problem. However, hydrogen molecules are very small (1.49 angstroms), making them prone to leakage during production, storage, transportation, and use. Simultaneously, hydrogen has a low ignition energy (0.02 mJ) and flash point (585℃), a rapid diffusion rate, and a wide explosion limit in air (4%~75%), posing serious safety hazards to the widespread application of hydrogen energy. Therefore, real-time monitoring of hydrogen concentration and leakage is necessary during hydrogen use. This places demands on hydrogen monitoring methods.
[0003] Metal-oxide-semiconductor (MOS) based hydrogen sensors have attracted widespread attention due to their low cost, small size, and high sensitivity. The active sensitive layer formed by oxide sensing materials is the core of the sensor and is closely related to its sensing performance. Among many oxides, tungsten trioxide (WO3) is widely used for hydrogen sensing due to its simple preparation method, stable physicochemical properties, and high sensitivity to hydrogen. However, WO3 alone suffers from insufficient selectivity, slow response and recovery speeds, and poor long-term stability, which limits its application in practical environments to some extent. Therefore, further modification is needed to improve hydrogen sensing performance.
[0004] Currently, modifications to WO3 mainly include compounding with compounds (ZnO, CoO) and loading with noble metals (Pd, Pt). Material composites can solve this problem to some extent, but material design is key. Ding et al. prepared WO3 / CoO composite materials via a two-step hydrothermal method, achieving a response value of 39 to 100 ppm hydrogen at 250°C (W. Ding, N. Ansari, Y. Yang, K. Bachagha, Superiorly sensitive and selective H2 sensor based on p-nheterojunction of WO3–CoO nanohybrids and its sensing mechanism, Int. J. Hydrogen Energy 46 (2021) 28823-28837.); Shiteng et al. prepared Pd-WO3 nanoplates via a hydrothermal method, achieving a response value of 1.6 to 100 ppm hydrogen at 200°C (S. Ma, F. Chen, Y. Liu, H. Zhang, P. Jia, D. Zhang, Pd-Doped WO3 Nanoplates for Hydrogen Sensing: Experimental Studies and Density Functional Theory Investigations, ACS Appl. Nano Mater. 7). (2024)15298-15307.). The above studies show that although constructing heterojunctions or noble metal loadings effectively improves the material's response to hydrogen, its operating temperature is still relatively high, and the improvement effect on hydrogen sensing performance is limited.
[0005] Therefore, the palladium (Pd)-supported WS2 / WO3 ternary system helps to alleviate the aforementioned difficulties. On the one hand, tungsten disulfide (WS2), as a two-dimensional transition metal material, has a high specific surface area and fast electron mobility. On the other hand, Pd has a high work function, which can reduce the activation energy and enhance chemical activity. Therefore, the Pd-WS2 / WO3 composite system has great application potential. However, currently, the loading form of noble metals is mostly nanoparticles, where only a portion of the atoms exposed on the surface play a role, greatly reducing the utilization rate of noble metal atoms and limiting its further performance optimization and practical application. Summary of the Invention
[0006] To address the problems of high operating temperature, low selectivity, slow response speed, and low catalytic efficiency of noble metals in existing gas sensors, this invention provides a Pd-SA / WOS ternary composite gas-sensitive material, its preparation method, and its applications. This invention successfully prepares a ternary composite gas-sensitive material by uniformly loading noble metal Pd in single-atom form onto the surface of a WS2 / WO3 composite. This material possesses high oxygen vacancies, high redox activity, optimized morphology, and an ideal band structure. In hydrogen detection, this material offers advantages such as low operating temperature, fast response speed, high sensitivity, and good selectivity, making it suitable for monitoring and early warning of hydrogen leaks.
[0007] A Pd-SA / WOS ternary composite gas-sensitive material, wherein the microstructure of the ternary composite gas-sensitive material is that Pd is uniformly distributed in the form of single atoms on the surface of the WS2 / WO3 composite, wherein the WS2 / WO3 composite is a flower-like structure assembled from WS2 / WO3 nanosheets, and the mass ratio of WS2 to WO3 in the WS2 / WO3 composite is 1:1.2~1.8.
[0008] Furthermore, the mass ratio of the WS2 / WO3 complex to the Pd single atom is 1:0.002~0.03.
[0009] Furthermore, the diameter of the ternary composite gas-sensitive material is 300~500 nm.
[0010] Furthermore, the WS2 / WO3 composite is a flower-like structure assembled from WS2 / WO3 nanosheets with a thickness of 3~10 nm.
[0011] Further, the WS2 / WO3 complex is prepared by the following method: tungsten hexachloride and thioacetamide are added to ethanol and stirred until the solution turns clear yellow. A hydrothermal reaction is then carried out at 150-200°C for 12-18 h. After the reaction, the mixture is cooled to room temperature, centrifuged, washed, and dried. The mixture is then calcined at 300-500°C for 1-3 h under a nitrogen atmosphere to obtain pure WS2. This WS2 is then calcined at 250-350°C for 1-2 h to obtain the WS2 / WO3 complex. The molar ratio of tungsten hexachloride to thioacetamide is 1:8-12, and the molar volume ratio of tungsten hexachloride to ethanol is 0.012-0.016 mol / L.
[0012] Furthermore, the present invention can adjust the thickness of WS2 / WO3 nanoflowers and the ratio of WS2 to WO3 in the composite by adjusting the temperature and time of calcination of pure WS2.
[0013] Another object of the present invention is to provide a method for preparing the above-mentioned ternary composite gas-sensitive material, comprising the following steps: adding the WS2 / WO3 composite to ethanol, sonicating it, and then slowly adding palladium chloride solution dropwise, stirring the reaction, and after the reaction is completed, centrifuging, washing and drying, and then calcining it under a nitrogen atmosphere, and finally cooling it to room temperature to obtain the Pd-WS2 / WO3 ternary composite gas-sensitive material.
[0014] In the above technical solution, the mass-to-volume ratio of the WS2 / WO3 complex to ethanol is 0.1~1 g / L.
[0015] In the above technical solution, the ultrasound time is 30~60 min.
[0016] In the above technical solution, the volume ratio of palladium chloride solution to ethanol is 1:1~10.
[0017] Furthermore, the concentration of the palladium chloride solution is 0.1~1.5 mmol / L.
[0018] In the above technical solution, the stirring reaction temperature is 50~70℃ and the time is 6~10 h.
[0019] In the above technical solution, the calcination temperature is 300~500℃ and the time is 1~3 h.
[0020] In the method described in this invention, the specific steps of centrifugation, washing and drying are as follows: after the reaction is completed and cooled to room temperature, the reaction solution is centrifuged, the precipitate is collected, and washed three times with anhydrous ethanol and deionized water respectively to obtain a solid product. Then, the product is placed in an oven and dried at 60-80°C for 6-24 h.
[0021] Another object of the present invention is to provide the application of the above-mentioned Pd-SA / WOS ternary composite gas-sensitive material in the preparation of hydrogen sensors.
[0022] This invention loads the noble metal Pd in single-atom form onto the surface of a WS2 / WO3 composite, which not only enhances the catalytic activity of the noble metal but also reduces the sensor's operating temperature and production costs. Furthermore, the introduction of WS2 improves the material's electron mobility, accelerating the sensing process of gas molecules and adsorbed oxygen. Moreover, by adjusting the reaction temperature, controlling the oxidation degree of WS2, and optimizing the size of the WS2 / WO3 composite and the WS2 / WO3 ratio, WS2 / WO3 nanoflowers with a large specific surface area were successfully fabricated. This significantly increases the number of active adsorption sites on the material surface, modulates the material's ground-state resistivity, and thus achieves rapid response at low temperatures.
[0023] The beneficial effects of this invention are: 1. This invention successfully loaded Pd in single-atom form onto the surface of a WS2 / WO3 composite through stepwise modification, constructing a Pd-SA / WOS ternary heterostructure with a flower-like microstructure. In this structure, the WS2 / WO3 nanoflowers have suitable sizes and a reasonable ratio of WS2 to WO3. Simultaneously, the highly catalytically active Pd single atoms are uniformly distributed without significant agglomeration. This greatly increases the specific surface area and active site concentration of the material, improves the band structure, and enhances the chemisorbed oxygen content, hydrogen reactivity, and carrier concentration, ultimately significantly improving the hydrogen sensing performance at low temperatures.
[0024] 2. The preparation method described in this invention is simple and easy to implement, requiring only hydrothermal treatment, calcination, and impregnation. It is low in cost and can effectively adjust the size of WS2 / WO3 nanoflowers, the ratio of WS2 to WO3, as well as the loading and dispersion of Pd single atoms, making it suitable for large-scale production.
[0025] 3. The Pd-SA / WOS ternary composite gas-sensitive material prepared in this invention exhibits excellent hydrogen sensing performance. Test results show that the optimal operating temperature of the material is significantly lower than that of traditional materials (from 180°C to 80°C). Among them, the material with a Pd loading of 1 wt% (1.0% Pd-SA / WOS) has the best sensing performance, with a response value of 225 for 100 ppm hydrogen at 80°C and a response recovery time of 1 / 88 s. It has excellent selectivity and anti-interference ability, and is suitable for efficient hydrogen detection and early warning, with a wide range of applications. Attached Figure Description
[0026] Figure 1 This is a SEM image of the Pd-SA / WOS ternary composite gas-sensitive material obtained in Example 1.
[0027] Figure 2 This is an HR-TEM image of the Pd-SA / WOS ternary composite gas-sensitive material obtained in Example 1.
[0028] Figure 3 This is an HR-TEM image of the Pd-NP / WOS ternary composite gas-sensitive material obtained in Comparative Example 5.
[0029] Figure 4 The temperature-response curves of gas sensors made from the gas-sensitive materials obtained in Comparative Examples 1-4 to 1000 ppm hydrogen are shown.
[0030] Figure 5 This is a temperature-response curve of a gas sensor made from the gas-sensitive materials obtained in Example 1, Comparative Example 1, Comparative Example 3 and Comparative Example 5 to 100 ppm hydrogen.
[0031] Figure 6This is a graph showing the response values of gas sensors made from the gas-sensitive materials obtained in Example 1, Comparative Example 1, Comparative Example 3, and Comparative Example 5 to 100 ppm of different gases at 80°C.
[0032] Figure 7 This is a response recovery time diagram of a gas sensor made based on the gas-sensitive material obtained in Example 1 to 100 ppm hydrogen at 80°C.
[0033] Figure 8 This is a response recovery time diagram of a gas sensor made from the gas-sensitive material obtained in Comparative Example 5 at 80°C to 100 ppm hydrogen. Detailed Implementation
[0034] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.
[0035] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.
[0036] One of the specific implementation methods: A method for preparing a Pd-SA / WOS ternary composite gas-sensitive low-temperature hydrogen sensing material includes the following steps: Step 1: Add tungsten hexachloride (WCl6) and thioacetamide (C2H5NS) to ethanol, stir until the solution turns clear yellow, and transfer it to an autoclave for hydrothermal reaction; Step 2: Cool the reaction vessel from Step 1 to room temperature, centrifuge, collect the precipitate, wash, and dry; Step 3: Place the dried powder obtained in Step 2 into a tube furnace and calcine it under a nitrogen atmosphere to obtain pure WS2; Step 4: Place the pure WS2 obtained in Step 3 in a muffle furnace and perform partial oxidation sintering at a certain temperature to obtain the WS2 / WO3 composite. Step 5: Add the WS2 / WO3 complex obtained in Step 4 to ethanol and sonicate. Step 6: Add PdCl2 solution dropwise and slowly to the solution obtained in Step 5, stir continuously at a certain temperature for several hours, centrifuge, collect the precipitate, wash and dry; Step 7: Place the dried powder obtained in Step 6 into a tube furnace and calcine it under a nitrogen atmosphere. After the calcination is completed, wait for the tube furnace to cool to room temperature to obtain the Pd single-atom-supported WS2 / WO3 ternary composite gas-sensitive material, denoted as Pd-SA / WOS.
[0037] In the method of the present invention, in step 1, the molar ratio of tungsten hexachloride to thioacetamide is 1:8~12, and the molar volume ratio of tungsten hexachloride to ethanol is 0.012~0.016 mol / L; the hydrothermal reaction temperature is 150~200°C, and the time is 12~18 h.
[0038] In the method of the present invention, in step 3, the calcination temperature is 300~500°C and the time is 1~3 h.
[0039] In the method of the present invention, in step 4, the calcination temperature is 250~350°C and the time is 1~2 h.
[0040] In the method of the present invention, in step 5, the mass-to-volume ratio of the WS2 / WO3 complex to ethanol is 0.1~1 g / L; the ultrasonic time is 30~60 min.
[0041] In the method of the present invention, in step 6, the volume ratio of the palladium chloride solution to ethanol is 1:1~10, and the concentration of the palladium chloride solution is 0.1~1.5 mmol / L; the stirring reaction temperature is 50~70℃, and the time is 6~10 h.
[0042] In the method of the present invention, in step 7, the calcination temperature is 300~500℃ and the time is 1~3 h.
[0043] In the method described in this invention, the specific steps of centrifugation, washing and drying are as follows: after the reaction is completed and cooled to room temperature, the reaction solution is centrifuged, the precipitate is collected, and washed three times with anhydrous ethanol and deionized water respectively to obtain a solid product. Then, the product is placed in an oven and dried at 60-80°C for 6-24 hours.
[0044] Example 1 A method for preparing a Pd-SA / WOS ternary composite gas-sensitive material includes the following steps: Step 1: Add 0.4 g WCl6 and 0.75 g thioacetamide to 60 mL of ethanol solution and stir continuously for 30 min until the solution turns clear yellow; transfer the above solution to a stainless steel autoclave lined with polytetrafluoroethylene and heat at 180°C for 15 h. Step 2: Cool the autoclave from Step 1 to room temperature, centrifuge, collect the precipitate, wash it three times with deionized water and ethanol respectively, and place it in an oven to dry at 60°C for 12 h; Step 3: Calcine the dried powder obtained in Step 2 at 400°C for 3 h under a nitrogen atmosphere to obtain pure WS2; Step 4: Place the pure WS2 obtained in Step 3 into a muffle furnace and calcine it at 300°C for 1 h to obtain the WS2 / WO3 complex, denoted as WOS-300; Step 5: Dissolve 25 mg of WOS-300 powder in 30 mL of ethanol and sonicate for 30 min; Step 6: Add 4.65 mL of 0.5 mM PdCl2 solution dropwise to the solution obtained in Step 5, and stir the mixture in an oil bath at 70°C for 6 h; centrifuge, collect the precipitate, wash it three times with deionized water and ethanol respectively, and place it in an oven to dry at 60°C for 12 h. Step 7: Place the dried powder obtained in Step 6 into a tube furnace and calcine it at 300°C for 2 h under a nitrogen atmosphere. After the calcination is completed, allow the tube furnace to cool to room temperature to obtain a ternary composite gas-sensitive material with a Pd single atom loading of 1 wt% and a WS2 to WO3 mass ratio of 1.57, denoted as 1.0% Pd-SA / WOS.
[0045] Scanning electron microscope (SEM) and high-resolution transmission electron microscope (HR-TEM) images of 1.0% Pd-SA / WOS are shown below. Figure 1 and 2 As shown. From Figure 1 It can be seen that the prepared 1.0% Pd-SA / WOS is a flower-like structure assembled from nanosheets, with obvious gaps between the sheets; the nanoflowers are about 500 nm in diameter, the sheet thickness is about 5 nm, and no obvious Pd nanoparticles were found on the surface. Figure 2 As can be seen, in the prepared 1.0% Pd-SA / WOS, Pd is uniformly distributed on the WO3 / WS2 surface in the form of single atoms.
[0046] Example 2 The difference between this embodiment and Example 1 is that in step 6, the volume of PdCl2 solution added is 2.34 mL, and the rest of the operation is the same as in Example 1. The final product is recorded as 0.5% Pd-SA / WOS.
[0047] Example 3 The difference between this embodiment and Example 1 is that in step 6, the volume of PdCl2 solution added is 7.03 mL, and the rest of the operation is the same as in Example 1. The final product is recorded as 1.5% Pd-SA / WOS.
[0048] Comparative Example 1 A method for preparing a WO3 gas-sensitive material includes the following steps: Step 1: Add 0.4 g WCl6 and 0.75 g thioacetamide to 60 mL of ethanol solution and stir continuously for 30 min until the solution turns clear yellow; transfer the above solution to a stainless steel autoclave lined with polytetrafluoroethylene and heat at 180°C for 16 h; after cooling to room temperature, centrifuge, collect the precipitate, wash three times with deionized water and ethanol respectively, place it in an oven and dry at 60°C for 12 h; calcine the dried powder at 400°C for 3 h under a nitrogen atmosphere to obtain pure WS2; Step 2: Place the obtained pure WS2 into a muffle furnace and calcine it at 600°C for 2 hours to obtain pure WO3 gas-sensitive material.
[0049] Comparative Example 1 uses a high temperature of 600°C to completely oxidize WS2 to WO3 as a comparative example. This condition is not within the scope of protection claimed by this invention.
[0050] Comparative Example 2 The difference between this comparative example and comparative example 1 is that in step 2, the calcination temperature is 250°C, and the rest of the operation is the same as that in comparative example 1. The product obtained is a binary composite gas-sensitive material of WS2 / WO3, denoted as WOS-250, in which the mass ratio of WS2 to WO3 is 1:1.39.
[0051] Comparative Example 3 The difference between this comparative example and comparative example 1 is that in step 2, the calcination temperature is 300°C, and the rest of the operation is the same as that in comparative example 1. The product obtained is a binary composite gas-sensitive material of WS2 / WO3, denoted as WOS-300, in which the mass ratio of WS2 to WO3 is 1:1.57.
[0052] Comparative Example 4 The difference between this comparative example and comparative example 1 is that in step 2, the calcination temperature is 350°C, and the rest of the operation is the same as that in comparative example 1. The product obtained is a binary composite gas-sensitive material of WS2 / WO3, denoted as WOS-350, in which the mass ratio of WS2 to WO3 is 1:1.66.
[0053] Comparative Example 5 The difference between this comparative example and Example 1 is as follows: In step 5, 25 mg of WOS-300 powder was dissolved in 30 mL of ethanol and sonicated for 30 min; in step 6, 234 μL of 1 M PdCl2 solution was added dropwise to the solution obtained in step 5, stirred at room temperature for 1 h, 141 μL of 0.05 M NaBH4 solution was added, centrifuged, the precipitate was collected, washed three times each with deionized water and ethanol, and placed in an oven to dry at 60°C for 12 h; the remaining operations were the same as in Example 1, and a ternary composite gas-sensitive material with a Pd nanoparticle loading of 1.0 wt% and a WS2 to WO3 mass ratio of 1:1.57 was obtained, denoted as 1.0%Pd-NP / WOS.
[0054] HR-TEM image of 1.0% Pd-NP / WOS as shown Figure 3 As shown, it can be seen that Pd nanoparticles with a particle size of about 5~10 nm can be clearly seen in the prepared 1.0% Pd-NP / WOS; the lattice stripes with a spacing of 0.238 nm correspond to the (111) crystal plane of the Pd nanoparticles.
[0055] The gas sensors prepared based on the gas-sensitive materials obtained in Example 1 and Comparative Examples 1-5 were used to study the sensing and testing of hydrogen gas. The results are shown in […]. Figures 4-8 The sensor made from the gas-sensitive material obtained in Example 1 is designated as the Pd-SA / WOS sensor; the sensor made from the gas-sensitive material obtained in Comparative Example 1 is designated as the pure WO3 sensor; the sensor made from the gas-sensitive material obtained in Comparative Example 2 is designated as the WOS-250 sensor; the sensor made from the gas-sensitive material obtained in Comparative Example 3 is designated as the WOS-300 sensor; the sensor made from the gas-sensitive material obtained in Comparative Example 4 is designated as the WOS-350 sensor; and the sensor made from the gas-sensitive material obtained in Comparative Example 5 is designated as the 1.0% Pd-NP / WOS sensor.
[0056] from Figure 4 It can be seen that the optimal temperature for the WOS-250 sensor is 160°C, while the optimal temperature for the WOS-300, WOS-350, and WO3 sensors is 180°C. The WOS-300 sensor has the highest response value (22.7) to 1000 ppm hydrogen at 180°C.
[0057] from Figure 5It can be seen that the optimal temperature for the WOS-300 sensor is 180°C, while the optimal temperatures for the 1.0% Pd-SA / WOS and 1.0% Pd-NP / WOS sensors are 80°C, showing a significant decrease in optimal operating temperature. Among them, the 1.0% Pd-SA / WOS sensor has the highest response value, with a response value of 225 for 100 ppm hydrogen, which is 184 times that of the WO3 sensor (1.22), 152 times that of the WOS-300 sensor (1.48), and 3.7 times that of the 1.0% Pd-NP / WOS sensor (60.7), respectively.
[0058] from Figure 6 It can be seen from this that the 1.0% Pd-SA / WOS sensor is most sensitive to H2, and its selectivity coefficient (S) is the highest. 氢气 / S 二甲苯 The H2 selectivity (13.23 for 100 ppm) indicates that the 1.0% Pd-SA / WOS gas-sensitive material has excellent H2 selectivity.
[0059] from Figure 7 As can be seen, the 1.0% Pd-SA / WOS sensor has a response and recovery time of 1 s and 88 s respectively to 100 ppm hydrogen at 80°C, which is extremely fast.
[0060] from Figure 8 It can be seen that the response and recovery times of the 1.0% Pd-NP / WOS sensor to 100 ppm hydrogen at 80°C are 9 s and 116 s, respectively.
Claims
1. A Pd-SA / WOS ternary composite gas-sensitive material, characterized in that: The microstructure of the ternary composite gas-sensitive material is that Pd is uniformly distributed in the form of single atoms on the surface of the WS2 / WO3 composite, wherein the WS2 / WO3 composite is a flower-like structure assembled from WS2 / WO3 nanosheets, and the mass ratio of WS2 to WO3 in the WS2 / WO3 composite is 1:1.2~1.
8.
2. The ternary composite gas-sensitive material according to claim 1, characterized in that: The mass ratio of the WS2 / WO3 complex to the Pd single atom is 1:0.002~0.
03.
3. The ternary composite gas-sensitive material according to claim 1, characterized in that: The diameter of the ternary composite gas-sensitive material is 300~500 nm.
4. The ternary composite gas-sensitive material according to claim 1, characterized in that: The WS2 / WO3 composite is a flower-like structure assembled from WS2 / WO3 nanosheets with a thickness of 3~10 nm.
5. The ternary composite gas-sensitive material according to claim 1, characterized in that: The WS2 / WO3 complex was prepared by the following method: tungsten hexachloride and thioacetamide were added to ethanol and stirred until the solution turned clear yellow. A hydrothermal reaction was then carried out at 150–200°C for 12–18 h. After the reaction, the mixture was cooled to room temperature, centrifuged, washed, and dried. The mixture was then calcined at 300–500°C for 1–3 h under a nitrogen atmosphere to obtain pure WS2. This WS2 was then calcined at 250–350°C for 1–2 h to obtain the WS2 / WO3 complex. The molar ratio of tungsten hexachloride to thioacetamide was 1:8–12, and the molar volume ratio of tungsten hexachloride to ethanol was 0.012–0.016 mol / L.
6. The method for preparing the ternary composite gas-sensitive material according to any one of claims 1 to 5, characterized in that: The WS2 / WO3 composite was added to ethanol, sonicated, and palladium chloride solution was added dropwise and slowly. The reaction was stirred and the mixture was centrifuged, washed and dried, and then calcined under a nitrogen atmosphere. After the reaction was completed, it was cooled to room temperature to obtain the Pd-WS2 / WO3 ternary composite gas-sensitive material.
7. The preparation method according to claim 6, characterized in that: The mass-to-volume ratio of the WS2 / WO3 complex to ethanol is 0.1~1 g / L; the volume ratio of the palladium chloride solution to ethanol is 1:1~10, wherein the concentration of the palladium chloride solution is 0.1~1.5 mmol / L.
8. The preparation method according to claim 6, characterized in that: The stirring reaction temperature is 50~70℃, and the time is 6~10 h.
9. The preparation method according to claim 6, characterized in that: The calcination temperature is 300~500℃, and the time is 1~3 h.
10. The application of the Pd-SA / WOS ternary composite gas-sensitive material according to claim 1 in the preparation of a hydrogen sensor.