Triethylamine room temperature sensor and method based on Sm-doped SnS2 / ZnS hierarchical microsphere structure

Abstract

The present invention discloses a triethylamine room-temperature sensor and method based on an Sm-doped SnS2 / ZnS hierarchical microsphere structure, which includes an Al2O3 ceramic tube, annular gold electrodes, platinum wire leads, and an Sm-doped SnS2 / ZnS hierarchical microsphere sensitive material; taking the Al2O3 ceramic tube as a substrate, two parallel annular gold electrodes are provided on the outer surface of the Al2O3 ceramic tube; the Sm-doped SnS2 / ZnS hierarchical microsphere sensitive material is coated on the annular gold electrodes and in the middle area between the two annular gold electrodes on the outer surface of the Al2O3 ceramic tube. Using the Sm-doped SnS2 / ZnS hierarchical microsphere as the sensitive material can significantly improve the triethylamine sensing performance at room temperature, including high sensitivity, fast response / recovery speed, low detection limit, and good selectivity, and promote the practical application of such sensors in the field of room-temperature gas detection.

Description

Technical Field

[0001] The invention belongs to the technical field of gas sensors, and in particular relates to a triethylamine room temperature sensor and a method. Background Art

[0002] Triethylamine (TEA), as a typical volatile organic compound (VOCs), is widely used as an organic solvent, catalyst, corrosion inhibitor and reagent for seawater desalination, and is a very important chemical organic raw material. At the same time, triethylamine is also a flammable, explosive and toxic organic compound. When the concentration of triethylamine in the air exceeds 10ppm, it is easy to cause serious health problems such as respiratory headache, chemical burns of eyes and skin, pulmonary edema, coma and even death. Therefore, for the safety of the public and families, it is necessary to develop a gas sensing device with good performance that can effectively monitor, record and analyze the instant information of triethylamine concentration in the air environment. Compared with other analytical techniques, resistive semiconductor gas sensors have attracted much attention due to their advantages of easy manufacturing and integration, low cost and ability to sensitively identify multiple gas components. However, gas sensors based on semiconductor metal oxides usually need to work in high temperature mode (150–400℃) to provide activation energy for gas-sensitive reactions, but this will shorten the sensor life and increase the manufacturing and packaging costs. At the same time, sensors with high operating temperatures are not suitable for integration into wearable devices because they are close to clothes or skin and rely on external energy supply. Room temperature gas sensors have greater development potential in this field because they can consume less energy, simplify manufacturing technology, and improve the integration of wearable devices.

[0003] So far, some layered metal dichalcogenides (LMDs) with filling layers, such as WS2, WSe2, SnSe2, and MoSe2, have been developed for the fabrication of low-temperature or room-temperature gas sensors. SnS2, as a group IV–VI semiconductor, forms a hexagonal CdI2-type stacking layer structure with tin ions sandwiched between two layers of closely packed sulfur ions in an octahedral coordination manner. SnS2 has attracted extensive attention in the field of gas sensing due to its excellent semiconductor properties, including high electronegativity, gas molecule adsorption ability with excellent surface dynamics, tunable band structure, high carrier mobility, non-toxicity, and stability. In recent years, a variety of methods have been used to regulate and modify the interface of gas sensing materials, including controlling grain size, engineering surface structure, and generating nanocomposites with various properties. The construction of multi-component heterojunction semiconductors is an effective strategy for the development of ultrasensitive and selective gas sensing platforms. Meanwhile, doping with rare earth elements is a facile and reliable method to improve gas sensing performance by generating more free electrons or oxygen vacancies when doped cations replace the original cations. Therefore, the present invention proposes an improved method for a triethylamine sensor based on a rare earth element Sm-doped SnS2 / ZnS hierarchical microsphere structure, and makes a room temperature sensor in the absence of other active energy (such as ultraviolet light) to track the state of triethylamine in the atmosphere. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the present invention provides a triethylamine room temperature sensor and method based on a Sm-doped SnS2 / ZnS graded microsphere structure, comprising an Al2O3 ceramic tube, an annular gold electrode, a platinum wire and a Sm-doped SnS2 / ZnS graded microsphere sensitive material; the Al2O3 ceramic tube is used as a substrate, and two parallel annular gold electrodes are provided on the outer surface of the Al2O3 ceramic tube; the Sm-doped SnS2 / ZnS graded microsphere sensitive material is coated on the annular gold electrode and the middle area between the two annular gold electrodes on the outer surface of the Al2O3 ceramic tube. Using the Sm-doped SnS2 / ZnS graded microsphere as a sensitive material can significantly improve the triethylamine sensing performance at room temperature, including higher sensitivity, faster reaction / recovery speed, lower detection limit and good selectivity, and promote the practical application of such a sensor in the field of room temperature gas detection.

[0005] The technical solution adopted by the present invention to solve the technical problem includes the following steps:

[0006] A triethylamine room temperature sensor based on a Sm-doped SnS2 / ZnS hierarchical microsphere structure, comprising an Al2O3 ceramic tube, a ring-shaped gold electrode, a platinum wire, and a Sm-doped SnS2 / ZnS hierarchical microsphere sensitive material;

[0007] The Al2O3 ceramic tube is used as a substrate, and two parallel annular gold electrodes are provided on the outer surface of the Al2O3 ceramic tube; there are two platinum wires, which are respectively connected to the two annular gold electrodes and serve as output signal lines of the sensor; the Sm-doped SnS2 / ZnS graded microsphere sensitive material is coated on the annular gold electrodes and the middle area between the two annular gold electrodes on the outer surface of the Al2O3 ceramic tube.

[0008] A method for preparing a triethylamine room temperature sensor based on a Sm-doped SnS2 / ZnS hierarchical microsphere structure comprises the following steps:

[0009] Step 1: adding zinc nitrate hexahydrate Zn(NO3)2·6H2O, tin tetrachloride pentahydrate SnCl4·5H2O and sodium hydroxide NaOH to a mixed solution containing anhydrous ethanol and deionized water, and stirring;

[0010] Step 2: dripping sodium hydroxide aqueous solution into the mixed solution obtained in step 1, transferring the suspension into a flask for heating, reflux and condensation, cooling naturally to room temperature, centrifuging the white precipitate, washing and drying at a set temperature for at least 24 hours to obtain ZnSn(OH)6 microspheres;

[0011] Step 3: The ZnSn(OH)6 microspheres obtained in step 2 are completely dispersed in deionized water under continuous magnetic stirring; an aqueous solution containing thioacetamide TAA and Sm(NO3)3·6H2O are added and stirred, and then acetic acid ice agent is added dropwise and stirred and mixed thoroughly;

[0012] Step 4: The mixed solution obtained in step 3 is transferred to an autoclave with a polytetrafluoroethylene liner, sealed and heated at a set temperature, and then naturally cooled to room temperature, and the yellow precipitate is collected by centrifugation, washed and dried for at least 24 hours to obtain a SnS2 / ZnS graded microsphere sensitive material based on Sm doping;

[0013] Step 5: Take the powder of SnS2 / ZnS graded microsphere sensitive material based on Sm doping and mix it evenly with ethanol solution to form a slurry, and use a brush to dip the slurry and apply it on the annular gold electrode and the middle area between the two annular gold electrodes on the outer surface of the Al2O3 ceramic tube to obtain an alumina ceramic tube coated with the graded microsphere sensitive material;

[0014] Step 6: After the alumina ceramic tube coated with the Sm-doped SnS2 / ZnS graded microsphere sensitive material is dried at a set temperature, the platinum wire of the sensor is welded to a plastic base with a metal joint to prepare a triethylamine room temperature sensor based on the Sm-doped SnS2 / ZnS graded microsphere structure.

[0015] Preferably, the step 1 is specifically as follows: 0.9 g zinc nitrate hexahydrate Zn(NO3)2·6H2O, 1.05 g tin tetrachloride pentahydrate SnCl4·5H2O and 1.2 g sodium hydroxide NaOH are added to a mixed solution containing 30 ml anhydrous ethanol and 50 ml deionized water.

[0016] Preferably, the heating reflux condensation in step 2 is maintained at 80° C. for 3 hours.

[0017] Preferably, the drying temperature at the set temperature for at least 24 hours in step 2 is 60°C.

[0018] Preferably, in step 4, the set temperature in the autoclave is 160° C. and the heating is performed for 8 hours.

[0019] Preferably, the drying at the set temperature in step 6 is specifically drying at 60° C. for 2 hours.

[0020] The beneficial effects of the present invention are as follows:

[0021] 1. The present invention provides a triethylamine room temperature sensor based on a Sm-doped SnS2 / ZnS hierarchical microsphere structure, which uses the Sm-doped SnS2 / ZnS hierarchical microsphere structure as a sensitive material to form a nn nano heterojunction, a high crystal defect density and Sm 3+ / Sm 2+ Yes, it achieves good electrical conductivity and chemical stability at room temperature. At the same time, the sensitivity of gas detection is greatly improved and the detection limit is reduced. It can be used for the detection of low-concentration triethylamine in the atmospheric environment at room temperature.

[0022] 2. The present invention provides a method for preparing a triethylamine room temperature sensor based on a Sm-doped SnS2 / ZnS graded microsphere structure. The Sm-doped SnS2 / ZnS graded microspheres are prepared by condensation reflux and hydrothermal process. The preparation method is simple and the obtained triethylamine sensor has excellent performance, which is conducive to mass industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the structure of the sensor of the present invention.

[0024] Figure 2 XRD diffraction patterns of SnS2 / ZnS microspheres synthesized with different Sm doping concentrations according to the embodiments of the present invention.

[0025] Figure 3 PL spectra of SnS2 / ZnS microspheres synthesized with different Sm doping concentrations under 532nm light excitation according to the embodiments of the present invention.

[0026] Figure 4SEM images of SnS2 / ZnS microspheres synthesized with different Sm doping concentrations according to the embodiments of the present invention.

[0027] Figure 5 This is a comparison chart of the continuous responses of sensors prepared with different Sm doping concentrations to 100 ppm triethylamine at room temperature according to an embodiment of the present invention.

[0028] Figure 6 This is a comparison diagram of the response recovery characteristic curves of sensors prepared with different Sm doping concentrations in the embodiments of the present invention to 10-500 pm triethylamine at room temperature (20° C., 25% RH).

[0029] Figure 7 This is a repeatability test curve of the sensor using SnS2 / ZnS-3.0 as the sensitive material in an embodiment of the present invention; (SnS2 / ZnS-3.0 was measured to 100 ppm triethylamine for five cycles).

[0030] Figure 8 Humidity influence curve of the sensor using SnS2 / ZnS-3.0 as the sensitive material in the embodiment of the present invention; (Changes in response and resistance under 100ppm triethylamine under different relative humidity conditions.)

[0031] In the figure: 1-Al2O3 ceramic tube, 2-annular gold electrode, 3-platinum wire, 4-Sm-doped SnS2 / ZnS graded microsphere sensitive material. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0033] The purpose of the present invention is to provide a triethylamine room temperature sensor based on a Sm-doped SnS2 / ZnS hierarchical microsphere structure and a preparation method thereof. Using the Sm-doped SnS2 / ZnS hierarchical microsphere as a sensitive material can significantly improve the triethylamine sensing performance at room temperature, including higher sensitivity, faster reaction / recovery speed, lower detection limit and good selectivity, and promote the practical application of such a sensor in the field of room temperature gas detection.

[0034] like Figure 1 As shown, a triethylamine room temperature sensor based on a Sm-doped SnS2 / ZnS hierarchical microsphere structure comprises an Al2O3 ceramic tube 1, a ring-shaped gold electrode 2, a platinum wire 3 and a Sm-doped SnS2 / ZnS hierarchical microsphere sensitive material 4;

[0035] The Al2O3 ceramic tube 1 is used as a substrate, and two parallel annular gold electrodes 2 are provided on the outer surface of the Al2O3 ceramic tube 1; there are two platinum wires 3, which are respectively connected to the two annular gold electrodes 2 and serve as output signal lines of the sensor; the Sm-doped SnS2 / ZnS graded microsphere sensitive material 4 is coated on the annular gold electrode 2 and in the middle area between the two annular gold electrodes 2 on the outer surface of the Al2O3 ceramic tube 1.

[0036] A method for preparing a triethylamine room temperature sensor based on a Sm-doped SnS2 / ZnS hierarchical microsphere structure comprises the following steps:

[0037] Step 1: 0.9 g zinc nitrate hexahydrate Zn(NO3)2·6H2O, 1.05 g tin tetrachloride pentahydrate SnCl4·5H2O and 1.2 g sodium hydroxide NaOH are added to a mixed solution containing 30 ml anhydrous ethanol and 50 ml deionized water, and stirred vigorously;

[0038] Step 2: Slowly drip sodium hydroxide aqueous solution into the mixed solution obtained in step 1, and then transfer the suspension to a flask for heating, reflux condensation, and maintain at 80°C for 3 hours. After naturally cooling to room temperature, the white precipitate is centrifuged, thoroughly washed, and dried at 60°C for at least 24 hours to obtain ZnSn(OH)6 microspheres;

[0039] Step 3: The ZnSn(OH)6 microspheres obtained in step 2 are completely dispersed in deionized water under continuous magnetic stirring; an aqueous solution containing thioacetamide TAA and a certain amount of Sm(NO3)3·6H2O are added and stirred, and then acetic acid ice agent is added dropwise and stirred and mixed thoroughly;

[0040] Step 4: The mixed solution obtained in step 3 is transferred to an autoclave with a polytetrafluoroethylene liner, sealed and heated at 160°C for 8 hours, then naturally cooled to room temperature, and the yellow precipitate is collected by centrifugation, thoroughly washed and dried for at least 24 hours to obtain a Sm-doped SnS2 / ZnS graded microsphere sensitive material;

[0041] Step 5: Take the powder of SnS2 / ZnS graded microsphere sensitive material based on Sm doping and mix it evenly with ethanol solution to form a slurry, and use a brush to dip the slurry and apply it on the annular gold electrode and the middle area between the two annular gold electrodes on the outer surface of the Al2O3 ceramic tube to obtain an alumina ceramic tube coated with the graded microsphere sensitive material;

[0042] Step 6: After the alumina ceramic tube coated with the Sm-doped SnS2 / ZnS graded microsphere sensitive material is dried at a set temperature, the platinum wire of the sensor is welded to a plastic base with a metal joint to prepare a triethylamine room temperature sensor based on the Sm-doped SnS2 / ZnS graded microsphere structure.

[0043] The sensor of the present invention is a triethylamine room temperature sensor based on a Sm-doped SnS2 / ZnS hierarchical microsphere structure. The sensitive mechanism of the triethylamine sensor with a SnS2 / ZnS hierarchical microsphere structure is that oxygen molecules in the air environment are easily adsorbed on the surface of the sensing material due to their large electronegativity (0.43 eV), and they can capture electrons from the conduction band of the SnS2 / ZnS hierarchical microspheres to form chemically adsorbed oxygen (O 2- ), thus forming an electron depletion layer at the gas-solid interface, resulting in an increase in sensor resistance. With the introduction of triethylamine gas, the active O 2- The adsorbed triethylamine analyte can be oxidized and release electrons back to SnS2 / ZnS. Therefore, a change in resistance is achieved after oxidation. The reaction equation is as follows:

[0044] 2Et2N-CH2-CH 3(ads) +O 2-(ads) →2Et2N-CH=CH2+2H2O+2e -

[0045] The triethylamine room temperature sensor based on the Sm-doped SnS2 / ZnS hierarchical microsphere structure of the present invention utilizes SnS2 / ZnS to form a nn nano heterojunction, a high crystal defect density, and Sm doped to generate 3+ / Sm 2+ The microstructure changes are equivalent to each other, so as to improve the sensitivity of gas detection. Specific embodiment:

[0047] like Figure 2 As shown in a, the XRD diffraction patterns of SnS2 / ZnS microspheres synthesized with different Sm doping concentrations (doping concentrations are 0, 1.5%, 3.0%, 4.5%, respectively labeled as SnS2 / ZnS-0, SnS2 / ZnS-1.5, SnS2 / ZnS-3.0, SnS2 / ZnS-4.5). The main diffraction peaks of SnS2 / ZnS-0 represent the crystal directions of SnS2 (001), (100), (011), (012) and (110), and the smaller reflection peaks correspond to the crystal directions of ZnS (111), (220) and (311), indicating the successful preparation of SnS2 / ZnS heterojunction microspheres. From the XRD spectra of SnS2 / ZnS-1.5, SnS2 / ZnS-3.0 and SnS2 / ZnS-4.5, it can be seen that the introduction of doping elements (Sm) does not destroy the crystal structure of SnS2 / ZnS heterojunction microspheres. Figure 2 As shown in b, with the increase of Sm doping amount, the (011) and (100) diffraction peaks move toward the low angle side, which may be due to the larger size of ion doping (Sm 3+ / Sm 2+) causes the host lattice to expand.

[0048] like Figure 3 As shown, the corresponding photoluminescence (PL) spectra of microspheres with different Sm doping concentrations (SnS2 / ZnS-0, SnS2 / ZnS-1.5, SnS2 / ZnS-3.0, SnS2 / ZnS-4.5) at an excitation wavelength of 532nm are used to study the defect characteristics. The deep level (DL) light emission is determined by the concentration of the corresponding crystal defect density. In this embodiment, the four samples show a wide range of deep level (DL) luminescence in the visible light region. Compared with other samples, SnS2 / ZnS-3.0 microspheres show a higher emission spectrum, which means that the defect concentration of the sample is higher.

[0049] like Figure 4 As shown in (a), the pure SnS2 / ZnS sample is composed of hierarchical microspheres assembled by many interlaced nanosheets. All microspheres are roughly uniform with an average diameter of about 1.1-1.3 μm. Figure 4 As shown in (b) and 4(c), the size of the SnS2 / ZnS sample gradually increases, and the diameter of the SnS2 / ZnS-3.0 sample is the largest, about 1.5-1.7μm, which is much larger than the grain size calculated from the XRD data. Studies have shown that the SnS2 / ZnS-3.0 sample contains a large number of grain boundaries and cracks, which produce very active sensing sites.

[0050] like Figure 5 As shown in the figure, with the increase of Sm doping, the response of SnS2 / ZnS-3.0 to 100ppm trimethylamine reaches a maximum value of 5.23 and then decreases. The response of SnS2 / ZnS-3.0 is significantly enhanced, which is nearly 1.5 times higher than that of pure SnS2 / ZnS graded microspheres. This enhancement may be due to the successful doping of Sm and the preparation of nn nanoheterojunction between SnS2 and ZnS.

[0051] like Figure 6 As shown, the response recovery characteristics of the sensor to 10-500 ppm of triethylamine at room temperature (20C, 25%RH) can be clearly found that the response of all sensors rises rapidly with the injection of triethylamine vapor and decreases with the release of triethylamine.

[0052] like Figure 7 As shown, the response of SnS2 / ZnS-3.0 to 100 ppm triethylamine was repeatedly measured at room temperature for 5 cycles. After 5 cycles of continuous measurement, the sensor showed good device repeatability and high stability.

[0053] like Figure 8As shown in the figure, in the relative humidity range of 25% to 90%, the response speed of SnS2 / ZnS-3.0 decreases, and the response / recovery speed is slow. The resistance of the sensor in the air environment also decreases with the increase of humidity. - The groups may compete with chemisorbed oxygen for active sites, resulting in slower reactions and prolonged reaction and recovery times.

[0054] Embodiment 1:

[0055] The specific manufacturing process of the triethylamine room temperature sensor with a Sm-doped SnS2 / ZnS graded microsphere structure with a doping concentration of 3.0% is as follows:

[0056] (1) 0.9 g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O), 1.05 g of tin tetrachloride pentahydrate (SnCl4·5H2O) and 1.2 g of sodium hydroxide (NaOH) were dispersed in a mixed solution containing 30 ml of anhydrous ethanol and 50 ml of deionized water. After vigorous stirring for 10 min, 10 ml of an aqueous solution containing 1.2 g of sodium hydroxide was slowly added to the above solution.

[0057] (2) The suspension was transferred to a flask and maintained at 80°C for 3 hours under heating reflux. After cooling naturally to room temperature, the white precipitate was centrifuged, washed thoroughly with deionized water, and dried at 60°C for at least 24 hours.

[0058] (3) 2 mmol of prepared ZnSn(OH)6 microspheres were completely dispersed in 40 ml of deionized water under continuous magnetic stirring. Then, 15 ml of aqueous solution containing 10 mmol of thioacetamide (TAA) was added, and a certain amount of Sm(NO3)3·6H2O (Sn 4+ After stirring for 5 minutes, 5 ml of glacial acetic acid was added dropwise. After further stirring for 30 minutes, the above solutions were fully mixed together.

[0059] (4) The mixture was transferred to an autoclave with a polytetrafluoroethylene liner, sealed and heated at 160°C for 8 hours. After cooling naturally to room temperature, the yellow precipitate was collected by centrifugation, washed thoroughly with deionized water to remove the unreacted solution, and dried at 60°C for at least 24 hours. SnS2 / ZnS microspheres with a Sm doping concentration of 3.0% were obtained, which were marked as SnS2 / ZnS-3.0.

[0060] (5) SnS2 / ZnS-3.0 graded microsphere sensitive material powder was uniformly mixed with ethanol solution to form a slurry, and the slurry was applied to the outer surface of the alumina ceramic tube with a brush to completely cover the gold electrode. After drying at 60°C for 2 hours, the platinum wire of the sensor was welded to a plastic base with a metal joint, thereby preparing a triethylamine room temperature sensor with a doping concentration of 3.0% Sm-doped SnS2 / ZnS graded microsphere structure;

[0061] Embodiment 2:

[0062] The specific production process of the triethylamine room temperature sensor with non-Sm-doped SnS2 / ZnS hierarchical microsphere structure is as follows:

[0063] (1) 0.9 g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O), 1.05 g of tin tetrachloride pentahydrate (SnCl4·5H2O) and 1.2 g of sodium hydroxide (NaOH) were dispersed in a mixed solution containing 30 ml of anhydrous ethanol and 50 ml of deionized water. After vigorous stirring for 10 min, 10 ml of an aqueous solution containing 1.2 g of sodium hydroxide was slowly added to the above solution.

[0064] (2) The suspension was transferred to a flask and maintained at 80°C for 3 hours under heating reflux. After cooling naturally to room temperature, the white precipitate was centrifuged, washed thoroughly with deionized water, and dried at 60°C for at least 24 hours.

[0065] (3) 2 mmol of the prepared ZnSn(OH)6 microspheres were completely dispersed in 40 ml of deionized water under continuous magnetic stirring. Then, 15 ml of an aqueous solution containing 10 mmol of thioacetamide (TAA) was added, stirred for 5 min, and then 5 ml of glacial acetic acid was added dropwise. After further stirring for 30 min, the above solutions were thoroughly mixed together.

[0066] (4) The mixture was transferred to an autoclave with a polytetrafluoroethylene liner, sealed and heated at 160°C for 8 hours. After cooling naturally to room temperature, the yellow precipitate was collected by centrifugation, washed thoroughly with deionized water to remove the unreacted solution, and dried at 60°C for at least 24 hours. Undoped SnS2 / ZnS microspheres were obtained, which were labeled as SnS2 / ZnS-0.

[0067] (5) The SnS2 / ZnS-0 graded microsphere sensitive material powder was uniformly mixed with an ethanol solution to form a slurry, and the slurry was applied to the outer surface of the alumina ceramic tube with a brush to completely cover the gold electrode. After drying at 60°C for 2 hours, the platinum wire of the sensor was welded to a plastic base with a metal joint, thereby preparing a triethylamine room temperature sensor with a non-Sm-doped SnS2 / ZnS graded microsphere structure.

[0068] Embodiment 3:

[0069] The specific manufacturing process of the triethylamine room temperature sensor with a Sm-doped SnS2 / ZnS graded microsphere structure with a doping concentration of 1.5% is as follows:

[0070] (1) 0.9 g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O), 1.05 g of tin tetrachloride pentahydrate (SnCl4·5H2O) and 1.2 g of sodium hydroxide (NaOH) were dispersed in a mixed solution containing 30 ml of anhydrous ethanol and 50 ml of deionized water. After vigorous stirring for 10 min, 10 ml of an aqueous solution containing 1.2 g of sodium hydroxide was slowly added to the above solution.

[0071] (2) The suspension was transferred to a flask and maintained at 80°C for 3 hours under heating reflux condensation. After naturally cooling to room temperature, the white precipitate was centrifuged, washed thoroughly with deionized water, and dried at 60°C for at least 24 hours.

[0072] (3) 2 mmol of prepared ZnSn(OH)6 microspheres were completely dispersed in 40 ml of deionized water under continuous magnetic stirring. Then, 15 ml of aqueous solution containing 10 mmol of thioacetamide (TAA) was added, and a certain amount of Sm(NO3)3·6H2O (Sn 4+ After stirring for 5 minutes, 5 ml of acetic acid ice agent was added dropwise. After further stirring for 30 minutes, the above solutions were fully mixed together.

[0073] (4) The mixture was transferred to an autoclave with a polytetrafluoroethylene liner, sealed and heated at 160°C for 8 hours. After cooling naturally to room temperature, the yellow precipitate was collected by centrifugation, washed thoroughly with deionized water to remove the unreacted solution, and dried at 60°C for at least 24 hours. SnS2 / ZnS microspheres with a Sm doping concentration of 1.5% were obtained, which were marked as SnS2 / ZnS-1.5.

[0074] (5) The SnS2 / ZnS-1.5 graded microsphere sensitive material powder was uniformly mixed with an ethanol solution to form a slurry, and the slurry was applied to the outer surface of the alumina ceramic tube with a brush to completely cover the gold electrode. After drying at 60°C for 2 hours, the platinum wire of the sensor was welded to a plastic base with a metal joint, thereby preparing a triethylamine room temperature sensor with a doping concentration of 1.5% Sm-doped SnS2 / ZnS graded microsphere structure.

[0075] Embodiment 4:

[0076] The specific manufacturing process of the triethylamine room temperature sensor with a Sm-doped SnS2 / ZnS graded microsphere structure with a doping concentration of 4.5% is as follows:

[0077] (1) 0.9 g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O), 1.05 g of tin tetrachloride pentahydrate (SnCl4·5H2O) and 1.2 g of sodium hydroxide (NaOH) were dispersed in a mixed solution containing 30 ml of anhydrous ethanol and 50 ml of deionized water. After vigorous stirring for 10 min, 10 ml of an aqueous solution containing 1.2 g of sodium hydroxide was slowly added to the above solution.

[0078] (2) The suspension was transferred to a flask and maintained at 80°C for 3 hours under heating reflux. After cooling naturally to room temperature, the white precipitate was centrifuged, washed thoroughly with deionized water, and dried at 60°C for at least 24 hours.

[0079] (3) 2 mmol of prepared ZnSn(OH)6 microspheres were completely dispersed in 40 ml of deionized water under continuous magnetic stirring. Then, 15 ml of aqueous solution containing 10 mmol of thioacetamide (TAA) was added, and a certain amount of Sm(NO3)3·6H2O (Sn 4+ After stirring for 5 minutes, 5 ml of glacial acetic acid was added dropwise. After further stirring for 30 minutes, the above solutions were fully mixed together.

[0080] (4) The mixture was transferred to an autoclave with a polytetrafluoroethylene liner, sealed and heated at 160°C for 8 hours. After cooling naturally to room temperature, the yellow precipitate was collected by centrifugation, washed thoroughly with deionized water to remove the unreacted solution, and dried at 60°C for at least 24 hours. SnS2 / ZnS microspheres with a Sm doping concentration of 4.5% were obtained, which were marked as SnS2 / ZnS-4.5.

[0081] (5) Take the SnS2 / ZnS-4.5 graded microsphere sensitive material powder and ethanol solution and mix them evenly to form a slurry. Use a brush to dip the slurry and apply it on the outer surface of the alumina ceramic tube so that it completely covers the gold electrode. Then dry it at 60°C for 2 hours, weld the platinum wire of the sensor to a plastic base with a metal joint, and the triethylamine room temperature sensor with a Sm-doped SnS2 / ZnS graded microsphere structure with a doping concentration of 4.5% can be prepared.

Claims

1. A method for preparing a triethylamine room temperature sensor based on a Sm-doped SnS2 / ZnS hierarchical microsphere structure, characterized in that: The sensor comprises an Al2O3 ceramic tube, a ring-shaped gold electrode, a platinum wire and a Sm-doped SnS2 / ZnS graded microsphere sensitive material; The Al2O3 ceramic tube is used as a substrate, and two parallel annular gold electrodes are arranged on the outer surface of the Al2O3 ceramic tube; there are two platinum wires, which are respectively connected to the two annular gold electrodes and serve as output signal lines of the sensor; the Sm-doped SnS2 / ZnS graded microsphere sensitive material is coated on the annular gold electrodes and the middle area between the two annular gold electrodes on the outer surface of the Al2O3 ceramic tube; The method for preparing the sensor comprises the following steps: Step 1: adding zinc nitrate hexahydrate Zn(NO3)2·6H2O, tin tetrachloride pentahydrate SnCl4·5H2O and sodium hydroxide NaOH to a mixed solution containing anhydrous ethanol and deionized water, and stirring; Step 2: dripping sodium hydroxide aqueous solution into the mixed solution obtained in step 1, transferring the suspension into a flask for heating, reflux and condensation, cooling naturally to room temperature, centrifuging the white precipitate, washing and drying at a set temperature for at least 24 hours to obtain ZnSn(OH)6 microspheres; Step 3: The ZnSn(OH)6 microspheres obtained in step 2 are completely dispersed in deionized water under continuous magnetic stirring; an aqueous solution containing thioacetamide TAA and Sm(NO3)3·6H2O are added and stirred, and then acetic acid ice agent is added dropwise and stirred and mixed thoroughly; Step 4: The mixed solution obtained in step 3 is transferred to an autoclave with a polytetrafluoroethylene liner, sealed and heated at a set temperature, and then naturally cooled to room temperature, and the yellow precipitate is collected by centrifugation, washed and dried for at least 24 hours to obtain a SnS2 / ZnS graded microsphere sensitive material based on Sm doping; Step 5: Take the powder of SnS2 / ZnS graded microsphere sensitive material based on Sm doping and mix it evenly with ethanol solution to form a slurry, and use a brush to dip the slurry and apply it on the annular gold electrode and the middle area between the two annular gold electrodes on the outer surface of the Al2O3 ceramic tube to obtain an alumina ceramic tube coated with the graded microsphere sensitive material; Step 6: After the alumina ceramic tube coated with the Sm-doped SnS2 / ZnS graded microsphere sensitive material is dried at a set temperature, the platinum wire of the sensor is welded to a plastic base with a metal joint to prepare a triethylamine room temperature sensor based on the Sm-doped SnS2 / ZnS graded microsphere structure; The step 1 is specifically as follows: 0.9 g zinc nitrate hexahydrate Zn(NO3)2·6H2O, 1.05 g tin tetrachloride pentahydrate SnCl4·5H2O and 1.2 g sodium hydroxide NaOH are added to a mixed solution containing 30 ml anhydrous ethanol and 50 ml deionized water.

2. The sensor preparation method according to claim 1, characterized in that: In the step 2, the heating reflux condensation is maintained at 80° C. for 3 hours.

3. The sensor preparation method according to claim 1, characterized in that: The temperature for drying at least 24 hours at the set temperature in step 2 is 60°C.

4. The sensor preparation method according to claim 1, characterized in that: In the step 4, the set temperature in the autoclave was 160° C. and heated for 8 hours.

5. The method for preparing a sensor according to claim 1, characterized in that: The drying at the set temperature in step 6 is specifically drying at 60° C. for 2 hours.

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