Preparation method and application of ammonia gas and triethylamine dual response type sensor based on copper-doped molybdenum oxide

Abstract

The invention provides a preparation method and application of an ammonia gas and triethylamine dual response type sensor based on copper-doped molybdenum oxide.The preparation method comprises the steps that MoS2 is synthesized through a simple and easy-to-operate hydrothermal method, 1.7 g of Na2MoO4. 2H2O and 2.24 g of CH4N2S are dissolved in 30 mL of pure water, and the solution is transferred into a 50 mL of an iron-fluorine stainless steel high-pressure kettle; and carrying out a hydrothermal reaction at 180-240 DEG C for 24 h, uniformly mixing, washing, and carrying out vacuum drying to obtain MoS2. And soaking MoS2 in a CuCl2 aqueous solution, drying, and calcining at 150-500 DEG C for 5 hours. And cooling to the room temperature to obtain the Cu-MoO3 (at) MoS2. And finally, coating Cu-MoO3 (at) MoS2 on a ceramic tube for aging, and welding a base to obtain the sensor. The sensor is simple in preparation mode, has the advantages of being short in response and recovery time, low in detection limit, excellent in repeatability, stability and selectivity and the like, and has wide application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor composite gas sensors and environmental monitoring, and specifically relates to the preparation and application of a dual-responsive sensor for ammonia and triethylamine based on copper-doped molybdenum oxide, which can be widely used in the fields of chemical industry, environmental monitoring, food safety, and public health. Background Art

[0002] With the acceleration of the industrialization process, ammonia (NH 3 ) and triethylamine (TEA) as important industrial gases have been widely used in the fields of chemical industry, pharmaceuticals, and agriculture. However, both of these gases have strong volatility and toxicity. NH 3 leakage may cause respiratory irritation and environmental pollution, while TEA may cause serious harm to human health and even trigger explosion accidents. Therefore, the development of a highly sensitive gas sensor capable of simultaneously detecting NH 3 and TEA has important practical significance.

[0003] In the field of gas sensors, metal oxide semiconductor (MOS) materials have been widely studied and applied due to their excellent gas-sensing properties. Molybdenum oxide (MoO 3 ) as a typical n-type semiconductor material has been used for various gas detections due to its high specific surface area, good chemical stability, and adjustable electrical properties. However, conventional MoO 3 still has problems such as insufficient sensitivity and poor selectivity in practical applications. In recent years, through metal doping modification, such as copper (Cu) doping, the gas-sensing performance of materials can be significantly improved. Copper doping can introduce additional active sites and optimize the electronic structure of materials, thereby enhancing the adsorption ability and response speed to target gases. For the dual detection requirements of NH 3 and TEA, existing research mostly focuses on single gas detection or uses complex sensor arrays. For example, a moisture-resistant and highly selective TEA gas-sensing material constructed based on the dual-metal MOF route has shown good application prospects. However, the development of a single sensor based on copper-doped molybdenum oxide to achieve dual responses to NH 3 and TEA can not only simplify the detection system but also improve the detection efficiency and reliability. There is already a certain foundation for the research of copper-doped molybdenum oxide materials. For example, a rare earth oxide-doped molybdenum-copper alloy composite material significantly improves the strength, toughness, and electrical conductivity of the material by optimizing the sintering performance. In addition, copper / copper molybdenum chalcogenide composite materials also show excellent catalytic performance, providing ideas for the further research of copper-doped molybdenum oxide materials.

[0004] In the aspect of sensor preparation, the copper-doped composite metal oxide exhibits excellent catalytic activity and stability through a unique hollow porous structure design. This structural design not only increases the specific surface area of the material but also provides more active sites for gas adsorption and transmission. At the same time, copper doping can effectively reduce the energy loss of interfacial charge transport, further improving the response speed and sensitivity of the sensor.

[0005] In summary, the development of the NH 3 and TEA dual sensors based on copper-doped molybdenum oxide can not only meet the requirements of high-sensitivity and high-selectivity gas detection in industrial and environmental fields but also provide an efficient technical solution for safety monitoring in related fields. Summary of the Invention

[0006] The present invention belongs to the technical field of semiconductor composite material gas sensors and environmental monitoring, and specifically relates to the preparation and application of a dual-response sensor for ammonia and triethylamine based on copper-doped molybdenum oxide, which can be widely applied in fields such as chemical engineering, environmental monitoring, food safety, and public health.

[0007] The material based on copper-doped molybdenum oxide described in the present invention has a chemical formula of Cu-MoO 3 @MoS 2 . First, MoS 2 was synthesized by a simple and easy-to-operate hydrothermal method. 1.7 g of Na 2 MoO 4 ·2H 2 O and 2.24 g of CH 4 N 2 S were dissolved in 30 mL of pure water and transferred to a 50 mL Teflon-lined stainless steel autoclave. Hydrothermal reaction was carried out at 180 - 240 °C for 24 h, mixed evenly, washed, and vacuum dried to obtain MoS 2 . Then, MoS 2 was immersed in an aqueous solution of CuCl 2 with a certain concentration, dried, and calcined at 150 - 500 °C for 5 h. After cooling to room temperature, Cu-MoO 3 @MoS 2 was obtained.

[0008] The present invention synthesized MoS 2 by the hydrothermal method, and then high-temperature calcination in a muffle furnace produced a flaky material Cu-MoO 3 @MoS 2 . Then, Cu-MoO 3 @MoS 2Age it after coating on the ceramic tube, weld the base, and obtain the ammonia sensor. Since this material has excellent adsorption properties as a gas-sensitive material, its selectivity and stability are also ideal, and it has broad application prospects.

[0009] A dual-response sensor for ammonia and triethylamine based on copper-doped molybdenum oxide and its preparation method according to the present invention are as follows:

[0010] A. Prepare the precursor (MoS 2 ) by hydrothermal method: Dissolve 1.694 g of sodium molybdate dihydrate and 2.24 g of thiourea in 25 mL of deionized water, and ultrasonically disperse. Transfer it to a 50 mL Teflon autoclave and react at 180 °C for 24 hours. After cooling, wash the product with deionized water and ethanol, and vacuum dry at 80 °C for 6 hours to obtain MoS 2 .

[0011] The hydrothermal reaction temperature of the mixed solution is 180 - 240 °C.

[0012] B. Add the precursor MoS 2 material obtained in step A to 5M CuCl 2 solution, and ultrasonically impregnate for 3 hours. Pour off the supernatant and dry at 80 °C for 6 hours. Anneal the dried powder at 150 - 500 °C for 5 hours. Grind to obtain MoO 3 @MoS 2 composite material.

[0013] The high-temperature calcination temperature is 150 - 500 °C, and the heating rate is 2 °C·min -1 .

[0014] C. Finally, coat Cu-MoO 3 @MoS 2 on the ceramic tube, age at 200 - 400 °C for 8 h, add a nickel-chromium alloy heating wire inside the ceramic tube of the sensor, and weld the heating wire and the Pt wire leads at both ends of the ceramic tube to the base with tin wire. The welding temperature is 250 °C, and the sensor is obtained.

[0015] The design idea of the present invention is as follows: At present, the mainstream gas-sensitive materials in ammonia and triethylamine sensors all face problems such as long response time and poor selectivity. Although doping modification with noble metals (Au, Pt), rare earths (La, Ce, Pr), etc. can improve the sensing performance of gas-sensitive materials to a certain extent, it still cannot meet the development requirements of low-cost commercialization. The combination of metal copper cations and molybdenum oxide, together with the advantages of the molybdenum disulfide microsphere structure, not only greatly improves the hole-electron combination, but also increases the adsorption area and the number of active sites. The performance of triethylamine and ammonia sensors is improved, and it has broad development prospects.

[0016] Characterize the obtained materials, and the test results of the sensor performance with dual responses to triethylamine and ammonia are shown in Figure 1-11 .

[0017] As can be seen from Figure 1 a microsphere structure with uniform growth of copper-doped molybdenum oxide, and the scanning electron microscope (SEM) characterization diagram of Cu-MoO 3 @MoS 2 obtained in step (2) of Example 1.

[0018] As can be seen from Figure 2 a transmission electron microscope (TEM) characterization diagram of Cu-MoO 3 @MoS 2 obtained in step (2) of Example 1.

[0019] As can be seen from Figure 3 an X-ray diffraction (XRD) characterization diagram of Cu-MoO 3 @MoS 2 obtained in step (2) of Example 1.

[0020] Figure 4 As can be seen, the X-ray photoelectron spectroscopy (XPS) characterization diagram of Cu-MoO 3 @MoS 2 obtained in step (2) of Example 1.

[0021] Figure 5 As can be seen, the change curve of the response values of a dual-responsive sensor to triethylamine and ammonia based on copper-doped molybdenum oxide obtained in step (5) of Example 1 with temperature. It can be seen from the figure that the optimal operating temperature is 250 °C.

[0022] Figure 6 As can be seen, the change curve of the response values of a dual-responsive sensor to triethylamine and ammonia based on copper-doped molybdenum oxide obtained in step (5) of Example 1 with different concentrations.

[0023] Figure 7 is the fitting of the change curve of the response values of a dual-responsive sensor to triethylamine and ammonia based on copper-doped molybdenum oxide obtained in step (5) of Example 1 with different concentrations. It can be seen from the figure that there is a strong linear relationship.

[0024] Figure 8 is the repeatability test curve of the response and recovery of a dual-responsive sensor to triethylamine and ammonia based on copper-doped molybdenum oxide obtained in step (5) of Example 1. It can be seen from the figure that the response is stable and the recovery is good after continuous multiple times.

[0025] Figure 9 It is the response and recovery time curves of a dual-response sensor for ammonia and triethylamine based on copper-doped molybdenum oxide obtained in step (5) of Example 1 to triethylamine with a concentration of 20 ppm and triethylamine with a concentration of 100 ppm. As can be seen from the figure, the sensor has a fast response and recovery time, and good recovery performance.

[0026] Figure 10 It is the response degree of a dual-response sensor for ammonia and triethylamine based on copper-doped molybdenum oxide obtained in step (5) of Example 1 to different gases. As can be seen from the figure, it has high selectivity.

[0027] Figure 11 It is the stability curve of the response degree of a dual-response sensor for ammonia and triethylamine based on copper-doped molybdenum oxide obtained in step (5) of Example 1 to 20 ppm ammonia and triethylamine within one month. As can be seen from the figure, a relatively high response value is still maintained after one month, indicating that the material has long-term stability. This ammonia sensor has broad development prospects and can be used in actual production and life.

[0028] In summary, the prepared Cu-MoO 3 @MoS 2 microspheres have more active sites and a larger surface area compared with other two-dimensional materials, and still form a spherical morphology self-assembled by flake-like structures through calcination. By adjusting the concentration of the copper solution, a gas-sensitive material with good TEA and NH 3 sensing performance (fast response, high selectivity, strong stability) can be generated.

[0029] Beneficial effects of the present invention: A Cu-MoO 3 @MoS 2 with a spherical morphology self-assembled by flake-like structures is prepared by using simple and easy-to-operate hydrothermal method and high-temperature calcination and other methods. Since Cu-MoO 3 @MoS 2 has more active sites, triethylamine and ammonia can be adsorbed strongly. This method is simple, fast, low-cost, and the obtained material has good structure and strong adsorption. Due to the structural advantages of this product, the electrode material has good ammonia sensing performance (fast response, high selectivity, strong stability), and it is expected to be widely used in the fields of chemical industry, environmental monitoring, food safety, public health, etc. Description of the Drawings

[0030] Figure 1 It is the scanning electron microscope (SEM) characterization of the copper-doped molybdenum oxide material in Example 1.

[0031] Figure 2It is the transmission electron microscope (TEM) characterization of the copper-doped molybdenum oxide material in Example 1.

[0032] Figure 3 It is the X-ray diffraction (XRD) characterization of the copper-doped molybdenum oxide material in Example 1.

[0033] Figure 4 It is the X-ray photoelectron spectroscopy (XPS) characterization of the copper-doped molybdenum oxide material in Example 1.

[0034] Figure 5 It is the response curve graph of the gas sensor element in Example 1 to a certain concentration of triethylamine and ammonia at different working temperatures.

[0035] Figure 6 It is the dynamic response curve graph of the gas sensor element in Example 1 to different concentrations of triethylamine and ammonia at the optimal working temperature.

[0036] Figure 7 It is the linear fitting graph of the relationship between the concentration of triethylamine and ammonia and the response value of the gas sensor element in Example 1 at the optimal working temperature.

[0037] Figure 8 It is the repeatability curve graph of the gas sensor element in Example 1 to 20 ppm triethylamine and 20 ppm ammonia at the optimal working temperature.

[0038] Figure 9 It is the response and recovery time curve graph of the gas sensor element in Example 1 to 20 ppm triethylamine and 100 ppm ammonia at the optimal working temperature.

[0039] Figure 10 It is the selectivity graph of the gas sensor element in Example 1 to different types of gases at the optimal working temperature.

[0040] Figure 11 It is the long-term stability test graph of the gas sensor element in Example 1 within one month at the optimal working temperature. Detailed implementation manners

[0041] To make the technical solutions, advantages, and invention purposes of the present invention clearer and more complete, the following further illustrates with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Based on the embodiments in this application, the technical features involved in various embodiments of the present invention described should all fall within the protection scope of this application.

[0042] In the following embodiments, the test methods are all conventional methods unless otherwise specified; the reagents and materials are all commercially available unless otherwise specified.

[0043] Example 1:

[0044] A preparation method of an ammonia and triethylamine dual-responsive sensor based on copper-doped molybdenum oxide, comprising the following steps:

[0045] (1) Prepare the precursor (MoS 2 ) by hydrothermal method: Dissolve 1.694 g of sodium molybdate dihydrate and 2.24 g of thiourea in 25 mL of deionized water, and ultrasonically disperse. Transfer to a 50 mL Teflon autoclave and react at 180 °C for 24 hours. After cooling, wash the product with deionized water and ethanol, and vacuum dry at 80 °C for 6 hours to obtain MoS 2 .

[0046] (2) Add 50 mg of MoS 2 to 10 M CuCl 2 solution, and ultrasonically impregnate for 3 hours. Pour off the supernatant and dry at 80 °C for 6 hours.

[0047] (3) Anneal the dried powder at 150 - 500 °C for 5 hours. Grind to obtain the Cu-MoO 3 @MoS 2 composite material.

[0048] (4) Cool to room temperature, add a nickel-chromium alloy heating wire in the middle of the ceramic tube, and weld the nickel-chromium heating wire and the Pt wire leads at both ends of the ceramic tube to the base with tin wire at a welding temperature of 250 °C to obtain the sensor.

[0049] (5) Use a sampling needle to inject a certain concentration of ammonia water into the gas sensor analyzer, use the corresponding resistance as the ordinate and time as the abscissa, record the change of resistance, and establish an ammonia response curve, where the response value (S) = Rg / Ra.

[0050] Example two:

[0051] A preparation method of an ammonia and triethylamine dual-responsive sensor based on copper-doped molybdenum oxide, comprising the following steps:

[0052] (1) Prepare the precursor (MoS 2 ) by hydrothermal method: Dissolve 1.694 g of sodium molybdate dihydrate and 2.24 g of thiourea in 25 mL of deionized water, and ultrasonically disperse. Transfer to a 50 mL Teflon autoclave and react at 180 °C for 24 hours. After cooling, wash the product with deionized water and ethanol, and vacuum dry at 80 °C for 6 hours to obtain MoS 2 .

[0053] (2) Add 50 mg of MoS 2 to 5 M CuCl 2 solution, and ultrasonically impregnate for 3 hours. Pour off the supernatant and dry at 80 °C for 6 hours.

[0054] (3) Anneal the dried powder at 150 - 500 °C for 5 hours. Grind to obtain Cu - MoO 3 @MoS 2 composite material.

[0055] (4) Cool to room temperature, add a nickel - chromium alloy heating wire in the middle of the ceramic tube, and weld the nickel - chromium heating wire and the Pt wire leads at both ends of the ceramic tube to the base with tin wire at a welding temperature of 250 °C to obtain the sensor.

[0056] (5) Use a sampling needle to inject a certain concentration of ammonia water into the gas - sensitive analyzer. Take the corresponding resistance as the ordinate and time as the abscissa, record the change of resistance, and establish an ammonia response curve, where the response value (S) = Rg / Ra.

[0057] Example 3:

[0058] A preparation method of an ammonia and triethylamine dual - response sensor based on copper - doped molybdenum oxide, comprising the following steps:

[0059] (1) Prepare the precursor (MoS 2 ) by hydrothermal method: Dissolve 1.694 g of sodium molybdate dihydrate and 2.24 g of thiourea in 25 mL of deionized water, and ultrasonically disperse. Transfer to a 50 - mL Teflon autoclave and react at 180 °C for 24 hours. After cooling, wash the product with deionized water and ethanol, and dry it in vacuum at 80 °C for 6 hours to obtain MoS 2 .

[0060] (2) Add 50 mg of MoS 2 to 20 M CuCl 2 solution, and ultrasonically impregnate for 3 hours. Pour off the supernatant and dry at 80 °C for 6 hours.

[0061] (3) Anneal the dried powder at 150 - 500 °C for 5 hours. Grind to obtain Cu - MoO 3 @MoS 2 composite material.

[0062] (4) Cool to room temperature, add a nickel - chromium alloy heating wire in the middle of the ceramic tube, and weld the nickel - chromium heating wire and the Pt wire leads at both ends of the ceramic tube to the base with tin wire at a welding temperature of 250 °C to obtain the sensor.

[0063] (5) Use a sampling needle to inject a certain concentration of ammonia water into the gas - sensitive analyzer. Take the corresponding resistance as the ordinate and time as the abscissa, record the change of resistance, and establish an ammonia response curve, where the response value (S) = Rg / Ra.

[0064] Example 4:

[0065] A preparation method of an ammonia and triethylamine dual-responsive sensor based on copper-doped molybdenum oxide, comprising the following steps:

[0066] (1) Prepare the precursor (MoS 2 ) by hydrothermal method: Dissolve 1.694 g of sodium molybdate dihydrate and 2.24 g of thiourea in 25 mL of deionized water, and ultrasonically disperse. Transfer to a 50 mL Teflon autoclave and react at 180 °C for 24 hours. After cooling, wash the product with deionized water and ethanol, and dry it in vacuum at 80 °C for 6 hours to obtain MoS 2 .

[0067] (2) Add 50 mg of MoS 2 to 40 M CuCl 2 solution, and ultrasonically impregnate for 3 hours. Pour off the supernatant and dry at 80 °C for 6 hours.

[0068] (3) Anneal the dried powder at 150 - 500 °C for 5 hours. Grind to obtain the Cu-MoO 3 @MoS 2 composite material.

[0069] (4) Cool to room temperature, add a nickel-chromium alloy heating wire in the middle of the ceramic tube, and weld the nickel-chromium heating wire and the Pt wire leads at both ends of the ceramic tube to the base with tin wire at a welding temperature of 250 °C to obtain the sensor.

[0070] (5) Use a sampling needle to inject a certain concentration of ammonia water into the gas-sensing analyzer. Take the corresponding resistance as the ordinate and time as the abscissa, record the resistance change, and establish an ammonia response curve, where the response value (S) = Rg / Ra.

Claims

1. A preparation method and application of a dual response sensor for ammonia and triethylamine based on copper-doped molybdenum oxide, comprising establishing an ammonia sensor based on nickel-iron bimetallic oxide, the specific steps of: (1) MoS2 is prepared by hydrothermal method; (2) Soaking the precursor MoS2 prepared in step (1) in a CuCl2 aqueous solution, drying, and annealing at 150-500° C. After cooling to room temperature, Cu-MoO3@MoS2 is obtained. (3) Cu-MoO3@MoS2 was added to ethanol for ultrasonic treatment, and then the material was coated on the surface of the Al2O3 ceramic tube, aged at high temperature for 8 h, taken out, a heating wire was added, and the base was welded to obtain a triethylamine / ammonia sensor.

2. The preparation method and application of a dual-response sensor for ammonia and triethylamine based on copper-doped molybdenum oxide according to claim 1, characterized in that: The concentration range of the CuCl2 solution in step (2) is 5M to 40M, and the immersion time is 2-4 hours.

3. The preparation method and application of a dual-response sensor for ammonia and triethylamine based on copper-doped molybdenum oxide according to claim 1, characterized in that: In step (3), the aging temperature is 150-500°C; the aging environment is air aging; the heating rate is 3°C·min -1 .

4. The preparation method and application of a dual-response sensor for ammonia and triethylamine based on copper-doped molybdenum oxide according to claim 1, characterized in that: The annealing time is 3-7h.

5. The preparation method and application of a dual-response sensor for ammonia and triethylamine based on copper-doped molybdenum oxide according to claim 1, characterized in that: In step (3), the Al2O3 ceramic tube has a length of 4 mm, an outer diameter of 1.2 mm, an electrode spacing of 0.8 mm ≤ ≤ 1 mm, and an electrode width of 0.5 mm ≤ ≤ 1 mm. The ceramic tube of the sensor has a nickel-chromium alloy heating wire inside. The heating wire and the Pt wire leads at both ends of the ceramic tube are welded to the base with tin wire. The welding temperature is 250°C.

6. The preparation method and application of a dual-response sensor for ammonia and triethylamine based on copper-doped molybdenum oxide according to claim 1, characterized in that: The gas sensor comprises the copper-doped molybdenum oxide composite material (Cu-MoO3@MoS2) described in claim 6 as a gas-sensitive material.

7. The preparation method and application of the copper-doped molybdenum oxide-based ammonia and triethylamine dual-responsive sensor according to any one of claims 1 to 6, wherein the gas sensor is a resistive gas sensor.

8. The composite material sensor according to claim 7 is used to detect ammonia (NH3) and triethylamine (TEA) under high temperature conditions.

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