Acetone gas sensor and preparation method thereof

Abstract

The present invention discloses an acetone gas sensor and a preparation method thereof, wherein the acetone gas sensor includes a micro-thermal electrode plate, a gas-sensitive layer formed of a BP / ZnFe2O4 composite material is coated on the micro-thermal electrode plate, the micro-thermal electrode plate includes a support film, a heater is fixed on the support film, an isolation film is covered on the heater, and an interdigital electrode is provided on the isolation film. The acetone gas sensor prepared by the present invention can sensitively detect acetone gas within the range of 100ppb-2ppm and exhibits a large response. Compared with the signal of pure ZnFe2O4 gas-sensitive material, the introduction of BP in the BP / ZnFe2O4 composite material accelerates the electron transfer rate of the gas-sensitive material, increases oxygen vacancies, increases the specific surface area, increases the adsorption sites of gas molecules, promotes the adsorption and diffusion of gas molecules in the sensitive film, thereby improving the adsorption / desorption speed and response strength of the sensor.

Description

Technical Field

[0001] The present invention relates to the technical field of gaseous acetone detection, in particular to an acetone gas sensor and a preparation method thereof. Background Art

[0002] Acetone (CH3COCH3), a representative volatile organic compound (VOC), is widely used in solvents, paints, and cosmetics. Acetone is a colorless, transparent liquid with a distinctive pungent odor. It is easily soluble in water and organic solvents such as methanol, ethanol, ether, chloroform, and pyridine. Acetone is inherently flammable, volatile, and chemically reactive. When exposed to products containing acetone, even low concentrations of volatilized acetone can be easily inhaled, causing serious health risks. Furthermore, relevant literature indicates that normal exhaled acetone concentrations in healthy individuals range from 300 to 900 ppb, while those in diabetic individuals can exceed 1.8 ppm.

[0003] Therefore, developing a gas sensor that can quickly detect slight changes in acetone has important practical significance.

[0004] The basic operating principle of a gas sensor is that when exposed to a target gas, it converts the gas volume fraction into a corresponding electrical signal through the adsorption and desorption of gas molecules, thereby detecting toxic and harmful gases. The microstructure of the sensitive material of a gas sensor plays a crucial role in improving the sensor's gas-sensing performance.

[0005] There are currently literature reports on the detection of acetone based on ZnFe2O4 composite materials. ZnFe2O4-based composite materials can detect a large range (acetone gas concentration is in the range of 0.5ppm~100ppm), but the detection lower limit is limited, and it is difficult to quickly distinguish slight changes in acetone concentration within the lower acetone gas concentration range (100ppb~2ppm).

[0006] In summary, current detection technology has difficulty distinguishing slight changes in acetone concentration in the range of 100ppb~2ppm. There is a need for an acetone gas sensor and detection method that can distinguish slight changes in acetone concentration in a low-concentration acetone environment and at the same time has to have high responsiveness and sensitivity. Summary of the Invention

[0007] The present invention aims to design a BP / ZnFe2O4 composite material to achieve acetone gas detection with a lower detection limit (100 ppb to 2 ppm), high sensitivity (Ra / Rg response to 500 ppb of acetone is approximately 5.34), and fast response (response time to 500 ppb of acetone is 6 seconds). The composite material can also be used to sensitively detect the presence of trace acetone gas in simulated respiratory gas, thereby resolving the technical problem that current acetone detection technology has difficulty in quickly distinguishing subtle changes in acetone concentration within the 100 ppb to 2 ppm range.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0009] An acetone gas sensor comprises a micro-thermal electrode plate on which a gas sensitive layer formed of a BP / ZnFe2O4 composite material is coated.

[0010] Preferably, the micro-thermal electrode plate includes a supporting film, a heater is fixed on the supporting film, the heater is covered with an isolation film, and interdigital electrodes are provided on the isolation film.

[0011] Preferably, the BP / ZnFe2O4 composite material is coated on the surface of the interdigital electrode.

[0012] Preferably, in the BP / ZnFe2O4 composite material, the mass ratio of BP to ZnFe2O4 is in the range of 1:180 to 1:200.

[0013] Preferably, the calculation formula of the response value of the acetone sensor to a certain concentration of acetone is: Ra / Rg; wherein: Rg is the stable resistance value under a certain concentration of acetone; Ra is the stable resistance value of the acetone sensor in dry air.

[0014] The BP material refers to black phosphorus (BP), which is an allotrope of elemental phosphorus.

[0015] The present invention also discloses a method for preparing an acetone gas sensor, wherein the method comprises the following steps:

[0016] Step 1: Dispersing predetermined masses of zinc acetate dihydrate and ferric chloride in predetermined volumes of ethanol and ethylene glycol, respectively, to form a mixed solution, and dispersing BP in anhydrous ethanol to obtain a BP-anhydrous ethanol dispersion;

[0017] Step 2: Mixing the mixed solution obtained in step 1 and the BP-anhydrous ethanol dispersion and stirring to obtain a doping mixed solution;

[0018] Step 3: adding the doping mixture obtained in step 2 to the lining of the reactor for hydrothermal reaction;

[0019] Step 4: centrifuging the doped mixed solution after the hydrothermal reaction, repeatedly washing it with anhydrous ethanol, and then drying it in a vacuum drying oven to obtain a BP / ZnFe2O4 composite material;

[0020] Step 5: The BP / ZnFe2O4 composite material obtained in step 4 is dispersed in a solvent by a drop coating method and drop coated on the surface of the micro-hot electrode plate. The micro-hot electrode plate is then vacuum dried to obtain an acetone gas sensor with the BP / ZnFe2O4 composite material as the gas sensitive layer.

[0021] Preferably, the preset weight range of zinc acetate dihydrate described in step 1 is 0.8-0.9, the preset weight range of ferric chloride is 1.2-1.3; the preset weight range of ethanol is 22-24, and the preset weight range of ethylene glycol is 7-9, and the purity of ethanol and ethylene glycol is ≥99.7%.

[0022] Preferably, in the doping mixture, the mass ratio of BP to ZnFe2O4 is in the range of 1:180 to 1:200.

[0023] Preferably, the micro-thermal electrode plate in step 5 includes a supporting film, a heater is fixed on the supporting film, the heater is covered with an isolation film, an interdigital electrode is provided on the isolation film, and the BP / ZnFe2O4 composite solution obtained in step 4 is drop-coated on the surface of the interdigital electrode.

[0024] The present invention has the following beneficial effects:

[0025] 1. The acetone gas sensor prepared by the present invention uses a BP / ZnFe2O4 composite material as the gas sensitive layer. Compared with the signal of a single ZnFe2O4 gas-sensitive material, the signal of the BP / ZnFe2O4 composite gas-sensitive material formed by appropriate BP doping is faster with the introduction of BP, which increases the electron transfer rate of the gas-sensitive material, the oxygen vacancies, the specific surface area, and the adsorption sites of gas molecules. It promotes the adsorption and diffusion of gas molecules in the sensitive film, thereby improving the adsorption / desorption rate and response strength of the sensor.

[0026] 2. The acetone gas sensor prepared by the present invention has a large response to acetone gas with a gas concentration in the range of 100ppb~2ppm and a low detection limit;

[0027] 3. The acetone gas sensor prepared by the present invention has high sensitivity, and the response Ra / Rg to 500 ppb acetone is about 5.34;

[0028] 4. The acetone gas sensor prepared by the present invention has a fast response time of 6s to 500ppb acetone;

[0029] 5. The material used in the acetone gas sensor prepared by the present invention has a unique morphology, is clustered, and has uniform size and good physical form. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to make the purpose, technical solutions and advantages of the invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings, in which:

[0031] Figure 1 Schematic diagram of the structure of the acetone gas sensor of the present invention;

[0032] Figure 2 This is a SEM morphology image of the acetone gas sensor of the present invention;

[0033] Figure 3 This is a schematic diagram of the acetone gas sensor of the present invention detecting acetone;

[0034] Figure 4 This is a schematic diagram of the repeatability test of the acetone gas sensor of the present invention on 100 ppb acetone;

[0035] Figure 5 This is a graph showing the response and recovery time of the acetone gas sensor of the present invention to 500 ppb acetone;

[0036] Figure 6 This is a real-time resistance change curve of the acetone gas sensor of the present invention in an acetone environment of 100ppb~2ppm;

[0037] Figure 7 is the concentration and response fitting curve of the acetone gas sensor of the present invention;

[0038] Figure 8 Graph showing the sensing performance and long-term stability of the acetone gas sensor of the present invention in a humid environment;

[0039] Figure 9 This is a performance diagram of the acetone gas sensor of the present invention under simulated diabetic human exhalation. DETAILED DESCRIPTION

[0040] In order to better understand the purpose, structure and function of the present invention, an acetone gas sensor and a preparation method thereof of the present invention are further described in detail below with reference to the accompanying drawings.

[0041] The present invention solves the technical problem that current acetone detection technology is difficult to distinguish slight changes in acetone concentration in a low-concentration acetone environment (100ppb~2ppm), while also having high responsiveness and sensitivity.

[0042] like Figure 1As shown, based on the above technical problems to be solved, the present invention discloses an acetone gas sensor, including a micro-thermal electrode plate, on which a gas sensitive layer formed of a BP / ZnFe2O4 composite material is coated.

[0043] The micro-thermal electrode plate includes a supporting film, a heater is fixed on the supporting film, the heater is covered with an isolation film, interdigital electrodes are arranged on the isolation film, and the BP / ZnFe2O4 composite material is coated on the surface of the interdigital electrodes.

[0044] In the BP / ZnFe2O4 composite material, the mass ratio of BP to ZnFe2O4 is in the range of 1:180 to 1:200, and preferably the mass ratio of BP to ZnFe2O4 is 1:193.

[0045] When coating the gas sensitive layer, 100 μL of anhydrous ethanol was added to 10 mg of BP / ZnFe 2 O 4 composite material to prepare a paste, which was then coated on the surface of the interdigital electrode.

[0046] The calculation formula of the response value of the acetone sensor to a certain concentration of acetone is: Ra / Rg; where: Rg is the stable resistance value under a certain concentration of acetone; Ra is the stable resistance value of the acetone sensor in dry air.

[0047] The BP material refers to black phosphorus (BP), which is an allotrope of elemental phosphorus.

[0048] The present invention also discloses a method for preparing an acetone gas sensor, which comprises the following steps:

[0049] Step 1: Dispersing predetermined masses of zinc acetate dihydrate and ferric chloride in predetermined volumes of ethanol and ethylene glycol, respectively, to form a mixed solution, and dispersing BP in anhydrous ethanol to obtain a BP-anhydrous ethanol dispersion;

[0050] Step 2: Mixing the mixed solution obtained in step 1 and the BP-anhydrous ethanol dispersion and stirring to obtain a doping mixed solution;

[0051] Step 3: Add the doping mixture obtained in step 2 to the lining of the reactor and perform a hydrothermal reaction at 180°C;

[0052] Step 4: centrifuging the doped mixed solution after the hydrothermal reaction, repeatedly washing it with anhydrous ethanol, and then drying it in a vacuum drying oven to obtain a BP / ZnFe2O4 composite material;

[0053] Step 5: The BP / ZnFe2O4 composite material obtained in step 4 is dispersed in an ethanol solvent by a drop coating method and drop coated on the surface of the micro-hot electrode plate. The micro-hot electrode plate is then vacuum dried to obtain an acetone gas sensor with the BP / ZnFe2O4 composite material as the gas sensitive layer.

[0054] The zinc acetate dihydrate in step 1 is present in a predetermined weight range of 0.8 to 0.9 parts, and the ferric chloride is present in a predetermined weight range of 1.2 to 1.3 parts; the ethanol is present in a predetermined weight range of 22 to 24 parts, and the ethylene glycol is present in a predetermined weight range of 7 to 9 parts, with the purity of both ethanol and ethylene glycol being ≥ 99.7%. In a specific implementation, the weights of the zinc acetate dihydrate and ferric chloride are 0.878 g and 1.298 g, respectively. The volumes of the ethanol and ethylene glycol, calculated based on weight and density, are 30 ml and 8 ml, respectively.

[0055] Preferably, in step 3, the hydrothermal reaction time is 12 hours.

[0056] Wherein, in step 4, the drying temperature of the vacuum drying oven is 80° C. and the drying time is 12 h.

[0057] Wherein, the ethanol described in step 5 is anhydrous ethanol, and the purity of the solvent is ≥99.7%.

[0058] In step 5, the micro-thermal electrode plate includes a supporting film, a heater is fixed on the supporting film, the heater is covered with an isolation film, and interdigital electrodes are provided on the isolation film, and the BP / ZnFe2O4 composite solution obtained in step 4 is drop-coated on the surface of the interdigital electrodes.

[0059] Example 1

[0060] The acetone gas sensor was prepared using the following method, which includes the following steps:

[0061] Step 1: Disperse 0.878 g of zinc acetate dihydrate and 1.298 g of ferric chloride in 30 ml of anhydrous ethanol and 8 ml of ethylene glycol. After mixing, disperse 5 mg of BP in 5 ml of anhydrous ethanol to obtain a BP-anhydrous ethanol dispersion.

[0062] Step 2: The solutions obtained in step 1 were mixed and stirred at a speed of 700 r / min for 10 min to obtain a doping mixed solution;

[0063] Step 3: Add the doping mixture obtained in step 2 to the inner lining of a 100 ml reactor and perform a hydrothermal reaction at 180°C;

[0064] Step 4: The doped mixed solution after the hydrothermal reaction was centrifuged and repeatedly washed with anhydrous ethanol for 3 to 4 times, and then placed in a vacuum drying oven at 80°C for 12 hours to obtain a BP / ZnFe2O4 composite material;

[0065] Step 5: The BP / ZnFe2O4 composite material obtained in step 4 was dispersed in ethanol solvent by drop coating and drop coated on the surface of the micro-hot electrode plate. The micro-hot electrode plate was then vacuum dried (45°C) for 90 minutes to obtain an acetone gas sensor with the BP / ZnFe2O4 composite material as the gas sensitive layer.

[0066] Wherein, in the doping mixture described in step 2, the mass ratio of BP and ZnFe2O4 is:

[0067] BP:ZnFe2O4=5 mg:0.96 g.

[0068] Wherein, in step 3, the hydrothermal reaction time is 12 hours.

[0069] like Figure 2 SEM characterization showed that the BP / ZnFe2O4 composite in the prepared material was good, in which the flake BP was tightly attached to the spherical ZnFe2O4 particles.

[0070] The obtained BP / ZnFe2O4 composite material acetone gas sensor is used to detect acetone gas. The schematic diagram of BP / ZnFe2O4 device detecting acetone is shown in the figure. Figure 3 As shown, the results are as follows Figures 4 to 7 shown.

[0071] pass Figure 4 It can be found that under a low acetone environment, that is, under the condition of acetone gas concentration of 100 ppb, the acetone gas sensor based on BP / ZnFe2O4 composite material has good repeatability; wherein, the response is defined as Ra / Rg, Rg is the stable resistance value under a certain concentration of acetone, and Ra is the stable resistance value of the acetone sensor in dry air.

[0072] like Figure 5 As shown in the figure, in an acetone gas concentration environment of 500ppb, the acetone gas sensor based on BP / ZnFe2O4 composite material has a fast response and recovery time (6s / 63s) for detecting low concentration acetone, and has good sensitivity.

[0073] like Figure 6 As shown in the figure, the acetone gas sensor of BP / ZnFe2O4 composite material was tested in an environment with different acetone gas concentrations. The results showed that the acetone gas detection had a good concentration gradient in environments with different acetone gas concentrations.

[0074] like Figure 7 As shown in the figure, when the acetone gas concentration is in the range of 100 ppb~1.5 ppm, the acetone gas sensor based on BP / ZnFe2O4 composite material has good sensitivity (slope is 0.006 / ppb) and linearity (r 2 =0.98).

[0075] like Figure 8 As shown in Figure 2, the real-time responses of the acetone gas sensor based on the BP / ZnFe2O4 composite material to 100 ppb acetone at different relative humidity (RH) conditions (12%RH~68%RH) are shown in Figure 2. Figure 8 a and Figure 8 b, Figure 8 c is a comparison of the responses under the two conditions. With the increase of RH value, the response of acetone gas sensor of BP / ZnFe2O4 composite material to acetone is slightly enhanced. Although the water vapor concentration under the test conditions is much higher than that of acetone, the response of adding 100ppb acetone is about 2 times higher than that of pure humidity, indicating that the acetone sensor has good moisture resistance and good detection characteristics in humid environment, and has high practical application potential. At the same time, Figure 8 As shown in Figure d, the acetone sensor also exhibited good long-term stability over 34 days (coefficient of dispersion CV = 5.4%).

[0076] In addition, an application embodiment of an acetone gas sensor is disclosed herein, in which the acetone gas sensor disclosed in the present invention is used to detect the content of acetone in human breath. It should be noted that the acetone gas sensor disclosed in the present invention can be applied in many occasions and is not limited to this application embodiment. Figure 9 As shown, the acetone gas sensor disclosed in the present invention has good performance in detecting the acetone content in human breath under the condition of simulated pathological individuals (such as diabetes).

[0077] First, the exhaled breath of healthy and pathological individuals was simulated. The simulated normal exhaled breath consisted of ~75% nitrogen, ~20% oxygen, ~4% carbon dioxide (volume percentage), and water vapor carried away by the carbon dioxide flowing through the gas flowmeter. Compared to the exhaled breath of a healthy individual, the exhaled breath of the pathological individual contained an additional amount of acetone.

[0078] Then, four acetone concentrations of 100, 300, 500, and 700 ppb were selected for testing, and five consecutive breathing cycles were tested continuously, such as Figure 9 As shown in b, the baseline resistance is the stable resistance under simulated normal exhalation. The dynamic response results of the sensor are shown in Figure 9 c. It can be seen that the response of the sensor increases with the increase of acetone concentration and shows the following Figure 9 d shows good sensitivity (slope is 0.003 / ppb) and linearity (r 2 =0.93). This also proves that the acetone gas sensor disclosed in the present invention has good detection performance for weak acetone gas in the breath of pathological individuals.

[0079] The disclosed acetone gas sensor and its preparation method have the following technical advantages: The material used in the acetone gas sensor prepared by the present invention has a unique cluster-like morphology and uniform size, exhibiting excellent physical form. The acetone gas sensor prepared by the present invention uses a BP / ZnFe2O4 composite material as the gas-sensing layer. Compared to the signal of a ZnFe2O4 gas-sensing material alone, the signal of the BP / ZnFe2O4 composite material formed by appropriate BP doping is significantly improved. The introduction of BP accelerates the electron transfer rate of the gas-sensing material, increases oxygen vacancies, and increases the specific surface area. This increases the adsorption sites for gas molecules, promotes the adsorption and diffusion of gas molecules within the sensitive film, and thus enhances the sensor's adsorption / desorption rate and response strength. The acetone gas sensor prepared by the present invention exhibits a strong response to acetone gas in the gas concentration range of 100 ppb to 2 ppm and a low detection limit. The acetone gas sensor prepared by the present invention has high sensitivity, with a response Ra / Rg of approximately 5.34 to 500 ppb of acetone. The acetone gas sensor prepared by the present invention has a fast response time of 6 seconds to 500 ppb of acetone. The acetone gas sensor prepared by the present invention has excellent moisture resistance and good detection characteristics in humid environments. The response to 100 ppb of acetone in humid environments is approximately 2 times higher than the response to pure humidity, demonstrating great potential for practical application. The acetone gas sensor prepared by the present invention has excellent long-term stability, with a response coefficient of variation (CV) of 5.4% over 34 days. The material used in the acetone gas sensor prepared by the present invention has a unique morphology, with clusters of uniform size and good physical form.

[0080] It will be understood that the present invention is described by way of some embodiments, and it will be appreciated by those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. An acetone gas sensor comprising a micro-thermal electrode plate, characterized in that: The micro-thermal electrode plate is coated with a gas sensitive layer formed by a BP / ZnFe2O4 composite material; in the BP / ZnFe2O4 composite material, the mass ratio of BP to ZnFe2O4 is in the range of 1:180 to 1:200; BP is black phosphorus.

2. An acetone gas sensor according to claim 1, characterized in that: The micro-thermal electrode plate comprises a supporting film, a heater is fixed on the supporting film, the heater is covered with an isolation film, and interdigital electrodes are arranged on the isolation film.

3. An acetone gas sensor according to claim 2, characterized in that: The BP / ZnFe2O4 composite material is coated on the surface of the interdigital electrode.

4. An acetone gas sensor according to claim 1, characterized in that: The calculation formula of the response value of the acetone sensor to a certain concentration of acetone is: Ra / Rg; where: Rg is the stable resistance value under a certain concentration of acetone; Ra is the stable resistance value of the acetone sensor in dry air.

5. A method for preparing an acetone gas sensor, comprising preparing the acetone gas sensor according to claim 1, wherein: The following steps are involved: Step 1: Dispersing predetermined weight portions of zinc acetate dihydrate and ferric chloride in predetermined weight portions of ethanol and ethylene glycol, respectively, to form a mixed solution, and dispersing BP in anhydrous ethanol to obtain a BP-anhydrous ethanol dispersion; Step 2: The mixed solution obtained in step 1 and the BP-anhydrous ethanol dispersion are mixed and stirred to obtain a doping mixed solution; in the doping mixed solution, the mass ratio of BP to ZnFe2O4 is in the range of 1:180 to 1:200; Step 3: adding the doping mixture obtained in step 2 to the lining of the reactor for hydrothermal reaction; Step 4: centrifuging the doped mixed solution after the hydrothermal reaction, repeatedly washing it with anhydrous ethanol, and then drying it in a vacuum drying oven to obtain a BP / ZnFe2O4 composite material; Step 5: The BP / ZnFe2O4 composite material obtained in step 4 is dispersed in anhydrous ethanol solvent by a drop coating method and drop coated on the surface of the micro-hot electrode plate. The micro-hot electrode plate is then vacuum dried to obtain an acetone gas sensor with the BP / ZnFe2O4 composite material as the gas sensitive layer.

6. The method for preparing an acetone gas sensor according to claim 5, wherein: The preset weight range of zinc acetate dihydrate described in step 1 is 0.8-0.9, the preset weight range of ferric chloride is 1.2-1.3; the preset weight range of ethanol is 22-24, and the preset weight range of ethylene glycol is 7-9, and the purity of ethanol and ethylene glycol is ≥99.7%.

7. The method for preparing an acetone gas sensor according to claim 5, wherein: In step 5, the micro-thermal electrode plate includes a supporting film, a heater is fixed on the supporting film, the heater is covered with an isolation film, and interdigital electrodes are provided on the isolation film, and the BP / ZnFe2O4 composite solution obtained in step 4 is drop-coated on the surface of the interdigital electrodes.

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