Preparation method of niobium oxide-based 2-chloroethyl ethyl sulfide gas sensor

Abstract

The application discloses a preparation method of a NiO-based 2-chloroethyl ethyl sulfide gas sensor, and belongs to the technical field of gas sensors.The application aims at solving the problems of high working temperature, low response value and long recovery time of the existing 2-CEES gas sensor.The method comprises the following steps: firstly, compounding nickel sulfate hexahydrate and metal salt;secondly, adding ammonia water;thirdly, immersing and heating;fourthly, calcining;and fifthly, aging.The application is used for the preparation of the NiO-based 2-chloroethyl ethyl sulfide gas sensor.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of gas sensors. BACKGROUND

[0002] Dichlorodiethyl sulfide is a foaming agent which has great harm to the environment and human beings. If too much of this gas is inhaled by human body, it will cause serious damage to organs, so it is necessary to effectively detect dichlorodiethyl sulfide. Since the gas is very toxic, it is very dangerous to carry out experiments in the laboratory. Therefore, in experiments, a simulated gas similar in physical and chemical properties is generally used, and the simulated gas is less toxic. The chemical gas 2-chloroethyl ethyl sulfide (2-CEES) gas is often used as a simulated gas of dichlorodiethyl sulfide in the laboratory.

[0003] At present, there are many methods for detecting 2-CEES gas, such as ion mobility spectrometry, gas chromatography mass spectrometry, and Raman spectroscopy, etc. However, these detection means have the disadvantages of high price, long time-consuming, etc., and are not suitable for practical application. In comparison, metal oxide semiconductor gas sensitive sensors have been used to detect low-concentration gases due to their simplicity, low cost, and high portability.

[0004] However, there are few studies on 2-CEES sensors. Only the Chinese patent application document with publication number CN116642928A introduces a preparation method based on WO3 / Al2O3 / graphite composite material. WO3 and Al2O3 are mixed in a mortar and calcined at high temperature to collect the solid product. Next, it is mixed with a graphite solution, and by constant stirring, a WO3 / Al2O3 / graphite solution is obtained. After drying, this gas-sensitive material is obtained. When preparing the sensor, the material is mixed with water and coated on a ceramic tube to respond to 2-CEES gas. However, it has the problem of low response value, only about 69%, and high working temperature. Some metal oxide gas sensors for detecting 2-CEES gas are also reported in the literature. For example, Li et al. (Baosheng Li, Xue Ma, Yuying Xin, Zoltán Major, Xianfa Zhang, Tingting Wang, Lihua Huo, Xiaoli Cheng, Yingming Xu, In situ construction of hierarchical Fe2O3 nanotube arrays for real-time detection and degradation of 2-CEES gas, Sensors and Actuators B: Chemical, Volume 383, 2023, 133590) constructed Fe2O3 material for detecting 2-CEES gas. The recovery time of this sensor is 190 seconds, indicating poor recovery. For another example, Yoo et al. (Ran Yoo1, Chihon Oh, Min-Jung Song, Sungmee Cho, and Wooyoung Lee. Journal of Nanoscience and Nanotechnology, Volume 18, Number 2, February 2018, pp. 1232-1236(5)) created a ZnO material for detecting 2-CEES gas. However, its working temperature is 500°C, and the recovery time is 127 seconds, indicating that its working temperature is too high and its recovery is not good.

[0005] Therefore, the existing 2-CEES gas sensor has the problems of high working temperature, low response value, and long recovery time. SUMMARY

[0006] The application aims at solving the problems of high working temperature, low response value and long recovery time of the existing 2-CEES gas sensor, and further provides a preparation method of NiO-based 2-chloroethyl ethyl sulfide gas sensor.

[0007] The preparation method of the NiO-based 2-chloroethyl ethyl sulfide gas sensor is carried out according to the following steps:

[0008] I. Complexing of nickel sulfate hexahydrate and metal salt:

[0009] The nickel sulfate hexahydrate and the metal salt are dissolved in deionized water and magnetically stirred to obtain a clear and transparent solution;

[0010] II. Adding ammonia:

[0011] Ammonia is added to the clear and transparent solution and continues to be magnetically stirred to obtain a green solution;

[0012] III. Immersion and heating:

[0013] The ceramic tube is immersed in the green solution and sealed, and then is reacted at a temperature of 120-200 DEG C for 4-24 hours, and then is cooled to room temperature, and the ceramic tube is taken out, washed and dried to obtain the ceramic tube after immersion treatment;

[0014] IV. Calcination:

[0015] The ceramic tube after immersion treatment is calcined at a temperature of 400-700 DEG C in an air atmosphere for 1-4 hours to obtain the ceramic tube with the NiO / metal oxide composite material grown on the surface;

[0016] The metal oxide is iron oxide, copper oxide, cadmium oxide, zinc oxide, silver oxide, cobalt oxide or magnesium oxide;

[0017] V. Aging:

[0018] The ceramic tube with the NiO / metal oxide composite material grown on the surface is welded on the base, and then is subjected to aging treatment to obtain the NiO-based 2-chloroethyl ethyl sulfide gas sensor.

[0019] The application has the following beneficial effects:

[0020] (1) The synthesis method can be in-situ synthesized on the ceramic tube substrate, and has excellent development and application prospect.

[0021] (2) The synthesis method of the material is simple, low in cost, and the solvent used is water which is friendly to the environment, and is suitable for large-scale production.

[0022] (3) The gas sensor has low working temperature (150℃), super-high sensitivity, low response value, fast response and recovery ability, good selectivity, and extremely low detection limit (0.07ppm), and can detect 2-CEES gas. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 XRD image of the NiO gas sensitive material in the ceramic tube with NiO grown on the surface prepared in step four of Example Eight;

[0024] Figure 2 SEM image of the NiO gas sensitive material in the ceramic tube with NiO grown on the surface prepared in step four of Example Eight;

[0025] Figure 3 Gas sensing performance test diagram of the gas sensor prepared in Example Eight, (a) response diagram of 2-CEES gas with a concentration of 100ppm at different working temperatures, (b) selectivity of 2-CEES gas at 150℃, (c) response and recovery time of 100ppm 2-CEES gas at 150℃, and (d) response value of 0.1ppm 2-CEES gas at 150℃;

[0026] Figure 4 Gas sensing performance test diagram of the gas sensor prepared in Example Eight at 150℃, (a-b) response of 2-CEES gas with a concentration ranging from 0.07ppm to 100ppm, (c-d) relationship between response value and gas concentration of 2-CEES gas, (e) response and recovery process of 100ppm 2-CEES gas for 5 times in succession, and (f) performance test of 100ppm 2-CEES gas within 70 days;

[0027] Figure 5 XRD image and SEM image of the NiO / Fe2O3 gas sensitive material in the ceramic tube with NiO / Fe2O3 composite material grown on the surface prepared in step four of Example One;

[0028] Figure 6 Response and recovery curve of the gas sensor prepared in Example One at 150℃ for 50ppm 2-CEES gas;

[0029] Figure 7 XRD image and SEM image of the NiO / CuO gas sensitive material in the ceramic tube with NiO / CuO composite material grown on the surface prepared in step four of Example Two;

[0030] Figure 8 Response and recovery curve of the gas sensor prepared in Example Two at 150℃ for 50ppm 2-CEES gas;

[0031] Figure 9 XRD image and SEM image of NiO / CdO gas sensitive material in the ceramic tube with NiO / CdO composite material grown on the surface prepared in step four of example three;

[0032] Figure 10 Response recovery curve of the gas sensor prepared in example three at 150°C to 50ppm of 2-CEES gas;

[0033] Figure 11 XRD image and SEM image of NiO / ZnO gas sensitive material in the ceramic tube with NiO / ZnO composite material grown on the surface prepared in step four of example four;

[0034] Figure 12 Response recovery curve of the gas sensor prepared in example four at 150°C to 50ppm of 2-CEES gas;

[0035] Figure 13 XRD image and SEM image of NiO / Ag2O gas sensitive material in the ceramic tube with NiO / Ag2O composite material grown on the surface prepared in step four of example five;

[0036] Figure 14 Response recovery curve of the gas sensor prepared in example five at 150°C to 50ppm of 2-CEES gas;

[0037] Figure 15 XRD image and SEM image of NiO / Co3O4 gas sensitive material in the ceramic tube with NiO / Co3O4 composite material grown on the surface prepared in step four of example six;

[0038] Figure 16 Response recovery curve of the gas sensor prepared in example six at 150°C to 50ppm of 2-CEES gas;

[0039] Figure 17 XRD image and SEM image of NiO / MgO gas sensitive material in the ceramic tube with NiO / MgO composite material grown on the surface prepared in step four of example seven;

[0040] Figure 18 Response recovery curve of the gas sensor prepared in example seven at 150°C to 50ppm of 2-CEES gas. DETAILED DESCRIPTION

[0041] Detailed implementation one: the preparation method of the NiO-based 2-chloroethyl ethyl sulfide gas sensor in this implementation, which is carried out according to the following steps:

[0042] I. Nickel sulfate hexahydrate and metal salt complex:

[0043] Dissolve nickel sulfate hexahydrate and metal salt in deionized water and magnetically stir to obtain a clear transparent solution;

[0044] II. Add ammonia water:

[0045] Add ammonia water to the clear transparent solution and continue to magnetically stir to obtain a green solution;

[0046] III. Immersion and heating:

[0047] Immerse the ceramic tube in the green solution and seal, react at a temperature of 120℃-200℃ for 4h-24h, then cool to room temperature, take out the ceramic tube, wash and dry to obtain an immersion treated ceramic tube;

[0048] IV. Calcination:

[0049] Calcine the immersion treated ceramic tube in an air atmosphere at a temperature of 400℃-700℃ for 1h-4h to obtain a ceramic tube with NiO / metal oxide composite material grown on the surface;

[0050] The metal oxide is iron oxide, copper oxide, cadmium oxide, zinc oxide, silver oxide, cobalt oxide or magnesium oxide;

[0051] V. Aging:

[0052] Weld the ceramic tube with NiO / metal oxide composite material grown on the surface to the base, then perform aging treatment to obtain a NiO-based 2-chloroethyl ethyl sulfide gas sensor.

[0053] The beneficial effects of the present embodiment are:

[0054] (1) The synthesis method can be used for in-situ synthesis on a ceramic tube substrate, and has excellent development and application prospects.

[0055] (2) The synthesis method of the material is simple, low in cost, and uses water as the solvent, which is environmentally friendly and suitable for large-scale production.

[0056] (3) The gas sensor has a low working temperature (150℃), high sensitivity, low response value, fast response and recovery ability, good selectivity, and extremely low detection limit (0.07ppm), and can detect 2-CEES gas.

[0057] Specific embodiment two: The difference between the present embodiment and specific embodiment one is that the metal salt in step one is iron nitrate nonahydrate, copper acetate, cadmium acetate, zinc acetate, silver acetate, cobalt acetate or magnesium chloride. The others are the same as specific embodiment one.

[0058] Specific embodiment three: different from any one of the specific embodiment one or two, the molar ratio of the nickel sulfate hexahydrate to the metal salt in step one is 1:(0-0.2). The others are the same as the specific embodiment one or two.

[0059] Specific embodiment four: different from any one of the specific embodiment one to three, the volume ratio of the deionized water to the nickel sulfate hexahydrate in step one is 1 mmol:(5-20) mL. The others are the same as the specific embodiment three.

[0060] Specific embodiment five: different from any one of the specific embodiment one to four, the magnetic stirring in step one is specifically under the condition of 50 rpm-3000 rpm for 0.5 h-2 h; the magnetic stirring in step two is specifically under the condition of 50 rpm-3000 rpm for 0.5 h-2 h. The others are the same as the specific embodiment one to four.

[0061] Specific embodiment six: different from any one of the specific embodiment one to five, the volume ratio of the clear transparent solution to the ammonia water in step two is 1:(0.03-0.1). The others are the same as the specific embodiment one to five.

[0062] Specific embodiment seven: different from any one of the specific embodiment one to six, the mass percentage of the ammonia water in step two is 5%-20%. The others are the same as the specific embodiment one to six.

[0063] Specific embodiment eight: different from any one of the specific embodiment one to seven, the ceramic tube in step three is an Al2O3 ceramic tube. The others are the same as the specific embodiment one to seven.

[0064] Specific embodiment nine: different from any one of the specific embodiment one to eight, the temperature is increased to 400℃-700℃ at the temperature increasing rate of 1℃ / min-5℃ / min under the air atmosphere in step four. The others are the same as the specific embodiment one to eight.

[0065] Specific embodiment ten: different from any one of the specific embodiment one to nine, the aging treatment in step five is specifically under the condition of 90℃-150℃ for 24 h-72 h. The others are the same as the specific embodiment one to nine.

[0066] The beneficial effects of the present application are verified by the following examples:

[0067] Example one:

[0068] The application discloses a preparation method of a NiO-based 2-chloroethyl ethyl sulfide gas sensor, which is prepared by the following steps.

[0069] I. nickel sulfate hexahydrate and metal salt compounding:

[0070] The nickel sulfate hexahydrate and the metal salt are dissolved in deionized water, and under the condition that the rotating speed is 500 rpm, magnetic stirring is carried out for 0.5 h to obtain a clear transparent solution;

[0071] The molar ratio of the nickel sulfate hexahydrate and the metal salt is 1:0.05;

[0072] The volume ratio of the molar number of the nickel sulfate hexahydrate and the deionized water is 2.66 mmol:30 mL;

[0073] The metal salt is iron nitrate nonahydrate;

[0074] II. adding ammonia water:

[0075] The ammonia water is added into the clear transparent solution, and under the condition that the rotating speed is 500 rpm, magnetic stirring is continuously carried out for 1.5 h to obtain a green solution;

[0076] The volume ratio of the clear transparent solution and the ammonia water is 1:0.033, and the mass percentage of the ammonia water is 10%;

[0077] III. immersion and heating:

[0078] The ceramic tube is immersed in the green solution and sealed, and under the condition that the temperature is 180 DEG C, the immersion and heating are carried out for 4 h, then the ceramic tube is cooled to room temperature, taken out, washed and dried to obtain the ceramic tube after immersion treatment;

[0079] IV. calcination:

[0080] Under the condition that the air atmosphere and the temperature is 500 DEG C, the ceramic tube after immersion treatment is calcined for 2 h at a temperature rising rate of 2 DEG C / min to obtain the ceramic tube with the NiO / Fe2O3 composite material grown on the surface;

[0081] V. aging:

[0082] The ceramic tube with the NiO / Fe2O3 composite material grown on the surface is welded on a base, and then under the condition that the temperature is 150 DEG C, the aging is carried out for 24 h to obtain the NiO-based 2-chloroethyl ethyl sulfide gas sensor.

[0083] The ceramic tube in step III is an Al2O3 ceramic tube, and the Al2O3 ceramic tube is washed with deionized water for 3 times; the Al2O3 ceramic tube is provided with two gold electrodes above the Al2O3 ceramic tube, and the distance between the electrodes is about 2 mm, and each electrode is connected with a platinum wire.

[0084] Example two: The difference between this example and example one is that the metal salt in step one is copper acetate; and the ceramic tube with NiO / CuO composite material grown on the surface is prepared in step four. The others are the same as example one.

[0085] Example three: The difference between this example and example one is that the metal salt in step one is cadmium acetate; and the ceramic tube with NiO / CdO composite material grown on the surface is prepared in step four. The others are the same as example one.

[0086] Example four: The difference between this example and example one is that the metal salt in step one is zinc acetate; and the ceramic tube with NiO / ZnO composite material grown on the surface is prepared in step four. The others are the same as example one.

[0087] Example five: The difference between this example and example one is that the metal salt in step one is silver acetate; and the ceramic tube with NiO / Ag2O composite material grown on the surface is prepared in step four. The others are the same as example one.

[0088] Example six: The difference between this example and example one is that the metal salt in step one is cobalt acetate; and the ceramic tube with NiO / Co3O4 composite material grown on the surface is prepared in step four. The others are the same as example one.

[0089] Example seven: The difference between this example and example one is that the metal salt in step one is magnesium chloride; and the ceramic tube with NiO / MgO composite material grown on the surface is prepared in step four. The others are the same as example one.

[0090] Example eight: The difference between this example and example one is that the metal salt is omitted in step one; and the ceramic tube with NiO grown on the surface is prepared in step four. The others are the same as example one.

[0091] The gas sensor prepared in the example is detected for the gas sensing performance of 2-CEES gas:

[0092] The test platform is JF02F sensor test system of Kunming Guiyan Jin Feng Technology Co., Ltd. The test process is as follows: the temperature and humidity during the test are 25±1℃ and 30±5%RH respectively. The gas sensing test process is divided into the following steps: first, use the vacuum pump to extract 10000ml gas chamber to vacuum, use the syringe to inject the gas to be tested, then inject clean air into the gas chamber to balance the pressure inside and outside the bottle. When the voltage of the gas sensor in the air remains stable, put the gas sensor into the gas chamber, when the gas sensor contacts the 2-CEES gas, the resistance of the gas sensor will change. After timing for 100 seconds, take the sensor out of the gas chamber and recover in the air.

[0093] Figure 1 XRD pattern of the NiO gas sensing material in the ceramic tube with NiO grown on the surface prepared in Example Eight Step Four; the XRD pattern shows that the characteristic diffraction peaks appearing at 37.3°, 43.3°, 62.9° and 75.4° correspond to the (111), (200), (220) and (311) crystal planes of NiO (JCPDS No. 04-0835), respectively.

[0094] Figure 2 SEM image of the NiO gas sensing material in the ceramic tube with NiO grown on the surface prepared in Example Eight Step Four; as shown in the figure, the NiO material in the form of strips grows closely on the surface of the ceramic tube.

[0095] Figure 3 Gas sensing performance test pattern of the gas sensor prepared in Example Eight, (a) response to 2-CEES gas with a concentration of 100 ppm at different working temperatures, (b) selectivity of the NiO sensor to 2-CEES gas at 150°C, (c) response and recovery time of the NiO sensor to 100 ppm 2-CEES gas at 150°C, (d) response value of the NiO sensor to 0.1 ppm 2-CEES gas at 150°C; as shown in Figure 3 (a), the response of the gas sensor prepared in Example Eight to 2-CEES gas with a concentration of 100 ppm at different working temperatures is as follows: Figure 3 As can be seen from (a), when the working temperature is 150°C, the sensor has the highest response value to 100 ppm 2-CEES gas; the selectivity of the NiO sensor to 2-CEES gas is as shown in Figure 3 (b), from Figure 3 As can be seen from (b), the response value of the NiO sensor to 100 ppm ethanol, acetone, toluene, n-pentanol, diethylamine, formaldehyde and hydrazine hydrate at 150°C is low, while the response to 2-CEES with a concentration of 100 ppm is relatively large, much higher than the response to other gases; therefore, as mentioned above, the optimal working temperature of the NiO sensor for detecting 2-CEES gas is 150°C. As shown in Figure 3 (c), the response and recovery time of the NiO sensor to 100 ppm 2-CEES gas at a working temperature of 150°C are 100 seconds and 98 seconds, respectively, and the response value is 42.5. The response value of the NiO sensor to 0.1 ppm 2-CEES gas is 2.21, as shown in Figure 3 (d), which indicates that the NiO sensor can detect 2-CEES gas with very low concentration well. This is also beneficial for the application of the NiO sensor in practice, which can detect the leakage of 2-CEES gas as early as possible.

[0096] Figure 4Figures showing the gas sensing performance test of the gas sensor prepared in Example Eight at 150°C, (a-b) the response to 2-CEES gas with a concentration ranging from 0.07 ppm to 100 ppm, (c-d) the relationship between the response value of the sensor to 2-CEES gas and the gas concentration, (e) the response recovery process of the sensor to 100 ppm of 2-CEES gas for 5 times in succession, and (f) the performance test of the sensor to 100 ppm of 2-CEES gas within 70 days; the response of the sensor to 2-CEES gas with a concentration ranging from 0.07 ppm to 100 ppm is shown in (a-b), and the response value of the sensor to 2-CEES gas increases from 1.2 to 42.5 as the concentration of 2-CEES gas increases from 0.7 ppm to 100 ppm, as shown in (a-b). Figure 4 Figure 4 As shown in (a-b), the response value of the sensor to 2-CEES gas increases from 1.2 to 42.5 as the concentration of 2-CEES gas increases from 0.7 ppm to 100 ppm. Figure 4 (c-d), the response value of the sensor to 2-CEES gas has a linear relationship with the concentration of 2-CEES gas, indicating that the detection range of the sensor to 2-CEES gas is between 0.07 ppm and 100 ppm. The response recovery test of the sensor to 100 ppm of 2-CEES gas for 5 times in succession was conducted at the optimal working temperature of 150°C, and the test results are shown in (e). Figure 4 (e), it can be seen from the figure that the resistance value of the sensor can recover to the initial resistance value each time, which indicates that the reproducibility of the sensor to 2-CEES gas is good. The gas sensing performance test of the sensor to 100 ppm of 2-CEES gas was further conducted every seven days within 70 days, and the test results are shown in (f). Figure 4 (f), it can be seen from the figure that the response value of the sensor has no great change within the test period of 70 days, which indicates that the sensor has good long-term stability to 2-CEES gas.

[0097] Example Eight first in-situ grows NiO material on the ceramic tube, which has the advantages of simple production method, green environmental protection, and low cost. The NiO sensor obtained for 2-CEES gas detection has the advantages of high sensitivity, extremely low detection limit, and low working temperature, and can timely warn of the leakage of 2-CEES gas.

[0098] Figure 5 Figures showing the XRD image and SEM image of the NiO / Fe2O3 gas sensing material grown on the surface of the ceramic tube prepared in Step Four of Example One; it can be seen from the figures that the prepared material is a composite material of NiO and Fe2O3, and the NiO / Fe2O3 composite material is closely grown on the surface of the ceramic tube.

[0099] Figure 6 ​The response-recovery curve of the gas sensor prepared in Example One to 50 ppm 2-CEES gas at 150°C; as can be seen from the figure, the NiO / Fe2O3 composite material sensor can detect 2-CEES gas.

[0100] The gas sensor prepared in Example One has the best gas sensing performance at 150°C, the response value is 48.5 (50 ppm), the response-recovery time is 11 s and 67 s (50 ppm) respectively, and has good selectivity, reproducibility (5 times in succession), and long-term stability (70 days). The sensor has a good linear relationship between the concentration of 2-CEES gas of 0.7 ppm to 50 ppm and the response value, and as the concentration of 2-CEES gas increases from 0.7 ppm to 50 ppm, the response value of the sensor to 2-CEES gas also increases from 2 to 48.5.

[0101] Figure 7 The XRD image and SEM image of the NiO / CuO gas sensitive material on the surface of the ceramic tube prepared in step four of Example Two; as can be seen from the figure, it is proved that the prepared material is a composite material of NiO and CuO, and the NiO / CuO composite material is closely grown on the surface of the ceramic tube.

[0102] Figure 8 The response-recovery curve of the gas sensor prepared in Example Two to 50 ppm 2-CEES gas at 150°C; as can be seen from the figure, the NiO / CuO composite material sensor can detect 2-CEES gas.

[0103] The gas sensor prepared in Example Two has the best gas sensing performance at 150°C (50 ppm), the response value is 12.5 (50 ppm), the response-recovery time is 16 s and 105 s (50 ppm) respectively, and has good selectivity, reproducibility (5 times in succession), and long-term stability (70 days). The sensor has a good linear relationship between the concentration of 2-CEES gas of 1 ppm to 50 ppm and the response value, and as the concentration of 2-CEES gas increases from 1 ppm to 50 ppm, the response of the sensor to 2-CEES gas also increases from 1.2 to 12.5.

[0104] Figure 9 The XRD image and SEM image of the NiO / CdO gas sensitive material on the surface of the ceramic tube prepared in step four of Example Three; as can be seen from the figure, it is proved that the prepared material is a composite material of NiO and CdO, and the NiO / CdO composite material is closely grown on the surface of the ceramic tube.

[0105] Figure 10The response-recovery curve of the gas sensor prepared in Example Three at 150°C for 50ppm 2-CEES gas; as can be seen from the figure, the NiO / CdO composite material sensor can detect 2-CEES gas.

[0106] The gas sensor prepared in Example Three has the best gas sensing performance at 150°C, the response value is 14.8 (50ppm), the response-recovery time is 56s and 300s (50ppm) respectively, and has good selectivity, reproducibility (5 times in succession), long-term stability (70 days). The sensor has a good linear relationship between the concentration and the response value of 2-CEES gas in the range of 0.9ppm-50ppm, and the response of the sensor to 2-CEES gas increases from 1.2 to 14.8 as the concentration of 2-CEES gas increases from 0.9ppm to 50ppm.

[0107] Figure 11 The XRD image and SEM image of the NiO / ZnO gas sensitive material in the ceramic tube with the surface grown with the NiO / ZnO composite material prepared in Step Four of Example Four; as can be seen from the figure, it is proved that the prepared material is a composite material of NiO and ZnO, and the NiO / ZnO composite material is closely grown on the surface of the ceramic tube.

[0108] Figure 12 The response-recovery curve of the gas sensor prepared in Example Four at 150°C for 50ppm 2-CEES gas; as can be seen from the figure, the NiO / ZnO composite material sensor can detect 2-CEES gas.

[0109] The gas sensor prepared in Example Four has the best gas sensing performance at 150°C, the response value is 3.8 (50ppm), the response-recovery time is 60s and 1300s (50ppm) respectively, and has good selectivity, reproducibility (5 times in succession), long-term stability (70 days). The sensor has a good linear relationship between the concentration and the response value of 2-CEES gas in the range of 5ppm-50ppm, and the response of the sensor to 2-CEES gas increases from 1.2 to 3.8 as the concentration of 2-CEES gas increases from 5ppm to 50ppm.

[0110] Figure 13 The XRD image and SEM image of the NiO / Ag2O gas sensitive material in the ceramic tube with the surface grown with the NiO / Ag2O composite material prepared in Step Four of Example Five; as can be seen from the figure, it is proved that the prepared material is a composite material of NiO and Ag2O, and the NiO / Ag2O composite material is closely grown on the surface of the ceramic tube.

[0111] Figure 14The response-recovery curve of the gas sensor prepared in Example Five at 150°C for 50ppm 2-CEES gas; from the figure, it can be seen that the NiO / Ag2O composite material sensor can detect 2-CEES gas.

[0112] The gas sensor prepared in Example Five has the best gas sensing performance at 150°C, the response value is 20.5 (50ppm), the response-recovery time is 40s and 230s (50ppm) respectively, and has good selectivity, reproducibility (5 times in succession) and long-term stability (70 days). The sensor has a good linear relationship between the concentration of 2-CEES gas of 0.5ppm-50ppm and the response value, and as the concentration of 2-CEES gas increases from 0.5ppm to 50ppm, the response of the sensor to 2-CEES gas also increases from 1.2 to 20.5.

[0113] Figure 15 The XRD image and SEM image of the NiO / Co3O4 gas sensing material on the surface of the ceramic tube prepared in Step Four of Example Six in which the NiO / Co3O4 composite material grows; from the figure, it can be seen that the prepared material is a composite material of NiO and Co3O4, and the NiO / Co3O4 composite material grows closely on the surface of the ceramic tube.

[0114] Figure 16 The response-recovery curve of the gas sensor prepared in Example Six at 150°C for 50ppm 2-CEES gas; from the figure, it can be seen that the NiO / Co3O4 composite material sensor can detect 2-CEES gas.

[0115] The gas sensor prepared in Example Six has the best gas sensing performance at 150°C, the response value is 6.3 (50ppm), the response-recovery time is 55s and 320s (50ppm) respectively, and has good selectivity, reproducibility (5 times in succession) and long-term stability (70 days). The sensor has a good linear relationship between the concentration of 2-CEES gas of 1ppm-50ppm and the response value, and as the concentration of 2-CEES gas increases from 1ppm to 50ppm, the response of the sensor to 2-CEES gas also increases from 1.2 to 6.3.

[0116] Figure 17 The XRD image and SEM image of the NiO / MgO gas sensing material on the surface of the ceramic tube prepared in Step Four of Example Seven in which the NiO / MgO composite material grows; from the figure, it can be seen that the prepared material is a composite material of NiO and MgO, and the NiO / MgO composite material grows closely on the surface of the ceramic tube.

[0117] Figure 18The response-recovery curve of the gas sensor prepared in Example 7 to 50 ppm 2-CEES gas at 150°C; it can be seen from the figure that the NiO / MgO composite material sensor can detect 2-CEES gas.

[0118] The gas sensor prepared in Example 7 has the best gas sensing performance at 150°C, the response value is 21.5 (50 ppm), the response-recovery time is 70 s and 220 s (50 ppm) respectively, and has good selectivity, reproducibility (5 times in succession) and long-term stability (70 days). The sensor has good linear relationship between the concentration of 2-CEES gas of 0.5 ppm to 50 ppm and the response value, and the response of the sensor to 2-CEES gas increases from 1.2 to 21.5 as the concentration of 2-CEES gas increases from 0.5 ppm to 50 ppm.

Claims

1. A method for preparing a NiO-based 2-chloroethyl ethyl sulfide gas sensor, characterized in that... It is done in the following steps: I. Complexation of nickel sulfate hexahydrate with metal salts: Nickel sulfate hexahydrate and a metal salt were dissolved in deionized water and stirred magnetically to obtain a clear and transparent solution. II. Add ammonia: Adding ammonia to the clear, transparent solution and continuing magnetic stirring yields a green solution; III. Immersion Heating: The ceramic tube was immersed in a green solution and sealed. The reaction was carried out at a temperature of 120℃~200℃ for 4h~24h. Then it was cooled to room temperature, the ceramic tube was taken out, washed and dried to obtain the ceramic tube after immersion treatment. IV. Calcination: Under air atmosphere and temperature of 400℃~700℃, the impregnated ceramic tube is calcined for 1h~4h to obtain a ceramic tube with NiO / metal oxide composite material grown on the surface. The metal oxide is iron oxide, copper oxide, cadmium oxide, zinc oxide, silver oxide, cobalt oxide, or magnesium oxide; V. Aging: A ceramic tube with NiO / metal oxide composite material grown on its surface is welded onto a base and then aged to obtain a NiO-based 2-chloroethyl ethyl sulfide gas sensor.

2. The method for preparing the NiO-based 2-chloroethyl ethyl sulfide gas sensor according to claim 1, characterized in that... The metal salt mentioned in step one is ferric nitrate nonahydrate, copper acetate, cadmium acetate, zinc acetate, silver acetate, cobalt acetate, or magnesium chloride.

3. The method for preparing the NiO-based 2-chloroethyl ethyl sulfide gas sensor according to claim 1, characterized in that... The molar ratio of nickel sulfate hexahydrate to the metal salt mentioned in step one is 1:(0 to 0.2).

4. The method for preparing the NiO-based 2-chloroethyl ethyl sulfide gas sensor according to claim 1, characterized in that... The molar ratio of nickel sulfate hexahydrate to deionized water in step one is 1 mmol: (5-20) mL.

5. The method for preparing the NiO-based 2-chloroethyl ethyl sulfide gas sensor according to claim 1, characterized in that... The magnetic stirring described in step one is specifically performed at a speed of 50 rpm to 3000 rpm for 0.5 h to 2 h; the magnetic stirring described in step two is specifically performed at a speed of 50 rpm to 3000 rpm for 0.5 h to 2 h.

6. The method for preparing the NiO-based 2-chloroethyl ethyl sulfide gas sensor according to claim 1, characterized in that... The volume ratio of the clear, transparent solution to ammonia in step two is 1:(0.03-0.1).

7. The method for preparing the NiO-based 2-chloroethyl ethyl sulfide gas sensor according to claim 1, characterized in that... The ammonia solution mentioned in step two has a mass percentage of 5% to 20%.

8. The method for preparing the NiO-based 2-chloroethyl ethyl sulfide gas sensor according to claim 1, characterized in that... The ceramic tube mentioned in step three is an Al2O3 ceramic tube.

9. The method for preparing the NiO-based 2-chloroethyl ethyl sulfide gas sensor according to claim 1, characterized in that... In step four, the temperature is increased to 400℃ to 700℃ in air at a heating rate of 1℃ / min to 5℃ / min.

10. The method for preparing the NiO-based 2-chloroethyl ethyl sulfide gas sensor according to claim 1, characterized in that... The aging process described in step five is specifically carried out at a temperature of 90℃~150℃ for 24h~72h.

Images