Dimethyldisulfide gas sensor based on porous Cr2O3 nano material and preparation method thereof

Abstract

The invention belongs to the technical field of gas sensors, and particularly relates to a dimethyl disulfide gas sensor based on a porous Cr2O3 nano material and a preparation method of the dimethyl disulfide gas sensor. The porous Cr2O3 nano material is used as the sensitive material of the dimethyl disulfide gas sensor for the first time, and the resistance-type dimethyl disulfide gas sensor with excellent performance is constructed. The sensor fully utilizes the advantages of high sensitivity, low cost, simple device, easy integration and easy on-site continuous detection of a semiconductor resistance-type sensing material and the characteristics of high response to dimethyl disulfide and excellent selectivity of Cr2O3, and constructs the resistance-type sensor which is sensitive in response to dimethyl disulfide, good in selectivity, low in working temperature, economical and environment-friendly. Meanwhile, a good sensitive material is found for a dimethyl disulfide gas sensor, and a new application field is developed for Cr2O3.

Description

Technical Field

[0001] The invention belongs to the technical field of gas sensors, and in particular relates to a dimethyl disulfide gas sensor based on porous Cr2O3 nanomaterials and a preparation method thereof. Background Art

[0002] Dimethyl disulfide is a toxic gas or liquid with a foul odor. It is irritating to the eyes, skin and respiratory tract. Inhaling excessive gas can cause dizziness or suffocation. It mainly comes from the decomposition of sulfur-containing substances (such as protein substances) and emissions from industrial production processes such as paper mills and tanneries. According to the "Emission Standards for Odor Pollutants (GB14554-2018)", for municipal sewage, sludge treatment and garbage disposal facilities, paper mills, tanneries and other pollution sources, dimethyl disulfide is one of the eight major odorous gases that must be monitored compulsorily.

[0003] According to the detection principle, dimethyl disulfide sensors can be mainly divided into two types: semiconductor and electrochemical. Semiconductor dimethyl disulfide sensors have the advantages of low cost, simple operation, compatibility with semiconductor processes, and easy miniaturization and integration. The gas-sensing performance of semiconductor dimethyl disulfide sensors mainly depends on the gas-sensitive materials. At present, commercial semiconductor dimethyl disulfide sensors have disadvantages such as high operating temperature and poor gas selectivity. Summary of the invention

[0004] One of the purposes of the present invention is to provide a dimethyl disulfide gas sensor, which has high response sensitivity to dimethyl disulfide, good selectivity and low operating temperature, and can overcome the shortcomings of the dimethyl disulfide sensor in the prior art, such as low response and poor gas selectivity.

[0005] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a dimethyl disulfide gas sensor, comprising a substrate, a test electrode arranged on the upper surface of the substrate, and a heating electrode arranged on the lower surface of the substrate, and porous Cr2O3 nanoparticles are coated on the surface of the test electrode and the substrate where the test electrode is located as a sensitive layer.

[0006] As a further improvement of the dimethyl disulfide gas sensor:

[0007] Preferably, the substrate is an Al2O3 substrate.

[0008] Preferably, the test electrode is made of Pt or Au.

[0009] Preferably, the thickness of the gas-sensitive material is 0.5 μm-20 μm.

[0010] Preferably, the particle size of the porous Cr2O3 nanoparticles is 10nm-100nm.

[0011] Preferably, when the sensor is used to monitor dimethyl disulfide gas, the sensitive layer is heated to 20-200° C. by heating the electrode.

[0012] A second object of the present invention is to provide a method for preparing a dimethyl disulfide gas sensor as described in any one of the above, comprising the following steps:

[0013] S1. Evenly dispersing porous Cr2O3 nanoparticles with a particle size of 10 nm to 100 nm in anhydrous ethanol to obtain a gas-sensitive material slurry;

[0014] S2. Coat the gas-sensitive material slurry on the upper surface of the substrate with a coating thickness of 0.5 μm-20 μm, place it in air for aging, then set a test electrode on the upper surface of the substrate and a heating electrode on the lower surface of the substrate to obtain a Cr2O3 dimethyl disulfide gas sensor.

[0015] As the preparation method of dimethyl disulfide gas sensor is further improved:

[0016] Preferably, the dispersed concentration of the porous Cr2O3 nanoparticles in the gas-sensitive material slurry is 0.05g-0.3g / ml.

[0017] Preferably, in step S2, the substrate coated with the gas-sensitive material slurry is placed in air at 150-450° C. for aging for 12-168 hours.

[0018] Preferably, the preparation method of the porous Cr2O3 nanoparticles is a solution combustion method, using chromium nitrate as an oxidant (O) and glycine as a fuel (F), and adjusting the crystal phase and morphology of the product by changing the molar ratio of the fuel to the oxidant (F / O), and the specific steps are as follows:

[0019] S11, weigh chromium nitrate nonahydrate Cr(NO3)3·9H2O and glycine C2H5NO2 in a molar ratio of 1:(0.75-3.0), dissolve them in deionized water in sequence, the chromium ion concentration is 0.05M-0.5M, and obtain a transparent and clear precursor solution;

[0020] S12, heating the precursor solution in an oven at 300-500° C. for 0.2-5.0 h to obtain a crude powder;

[0021] S13. Grind the crude powder in anhydrous ethanol and dry it to obtain porous Cr2O3 nanoparticles with a particle size of 10nm-100nm.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) The raw material cost of the dimethyl disulfide gas sensor of the present invention is low, and the material preparation method solution combustion method is safer, simpler, more efficient and easier to mass produce than the hydrothermal method (high temperature and high pressure).

[0024] 2) The porous Cr2O3 nanoparticles prepared in the present invention have abundant three-dimensional mesh channels and a high specific surface area, which are beneficial to the rapid diffusion and adsorption of gas in the sensitive layer of the sensor, thereby improving the response sensitivity.

[0025] 3) The prior art discloses a dimethyl disulfide gas sensor using copper iron ore structure oxide CuGaO2 as a sensitive material, and at an optimal operating temperature of 140°C, the response value to 10ppm dimethyl disulfide is low (~4). The sensor prepared by the present invention has a response to dimethyl disulfide that is more than 20 times (up to 97) at an optimal operating temperature of 140°C, has better selectivity, has a low response to other common gases (such as methyl sulfide, hydrogen sulfide, methanol, ethanol, acetone), is insensitive to gases such as sulfur dioxide, carbon disulfide and trimethylamine, and can quickly and effectively detect dimethyl disulfide gas with a concentration of 0.1-100ppm in a variety of mixed gases. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a scanning electron microscope photograph of the porous Cr2O3 nanoparticles in Example 1.

[0027] Figure 2 This is a scanning electron microscope photograph of the porous Cr2O3 nanoparticles in Example 2.

[0028] Figure 3 This is a scanning electron microscope photograph of the porous Cr2O3 nanoparticles in Example 3.

[0029] Figure 4 This is the X-ray diffraction pattern of the porous Cr2O3 nanoparticles in Examples 1-3.

[0030] Figure 5 (a), (b), and (c) are respectively the response diagrams of the DC resistance of the dimethyl disulfide gas sensors prepared in Example 1, Example 2, and Example 3 to 10 ppm dimethyl disulfide gas at constant operating temperatures of 120°C, 140°C, 160°C, and 180°C; (d) is a comparison diagram of the responses of the three dimethyl disulfide gas sensors to 10 ppm dimethyl disulfide gas at 120°C, 140°C, 160°C, and 180°C; wherein R a Represents the resistance of the sensor in air, R g Indicates the resistance of the sensor in different concentrations of target gas.

[0031] Figure 6The following are the dynamic change diagram of the resistance of the dimethyl disulfide gas sensor prepared in Example 2 in 1-50ppm dimethyl disulfide gas at a constant operating temperature of 140°C (a), the relationship diagram between the response and the dimethyl disulfide gas concentration (b), the dynamic change diagram of the resistance in 10ppm dimethyl disulfide gas after 9 cycles (c), and the response comparison diagram to dimethyl disulfide and various common interfering gases (d); wherein the concentrations of dimethyl disulfide, methyl sulfide, methyl mercaptan, hydrogen sulfide, carbon disulfide and sulfur dioxide are 10ppm, and the concentrations of methanol, ethanol, acetone and trimethylamine are 100ppm. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] This embodiment provides a method for preparing a dimethyl disulfide gas sensor using porous Cr2O3 nanomaterial as a sensitive material, comprising the following steps:

[0035] Step 1: Dissolve 1 mmol of Cr(NO3)3·9H2O and 0.75 mmol of C2H5NO2 in 5 mL of deionized water, stir magnetically, and obtain a transparent and clear precursor solution;

[0036] Step 2, heating the precursor solution in an oven at 300°C for 0.5h to obtain a crude powder;

[0037] Step 3, grinding the crude powder in anhydrous ethanol, and finally drying it in an oven to obtain porous Cr2O3 nanoparticles;

[0038] Step five, evenly disperse 0.2 g of porous Cr2O3 nanoparticles in 1 mL of anhydrous ethanol to obtain a gas-sensitive material slurry, coat the gas-sensitive material slurry on the upper surface of the substrate with a coating thickness of 5 μm, and then age it in air at 200°C for 72 hours, and then set a Pt test electrode on the upper surface of the substrate and a heating electrode on the lower surface of the substrate to obtain a Cr2O3 dimethyl disulfide gas sensor 1.

[0039] Example 2

[0040] This embodiment provides a method for preparing a dimethyl disulfide gas sensor using porous Cr2O3 nanomaterial as a sensitive material, comprising the following steps:

[0041] Step 1: Dissolve 1 mol of Cr(NO3)3·9H2O and 1.67 mol of C2H5NO2 in 2 L of deionized water, stir magnetically, and obtain a transparent and clear precursor solution;

[0042] Step 2, heating the precursor solution in an oven at 400°C for 0.5h to obtain a crude powder;

[0043] Step 3, grinding the crude powder in anhydrous ethanol, and finally drying it in an oven to obtain porous Cr2O3 nanoparticles;

[0044] Step five, evenly disperse 0.2g of porous Cr2O3 nanoparticles in 1mL of anhydrous ethanol to obtain a gas-sensitive material slurry, coat the gas-sensitive material slurry on the upper surface of the substrate with a coating thickness of 5μm, and then age it in air at 200°C for 72h, and then set a Pt test electrode on the upper surface of the substrate and a heating electrode on the lower surface of the substrate to obtain a Cr2O3 dimethyl disulfide gas sensor 2.

[0045] Example 3

[0046] This embodiment provides a method for preparing a dimethyl disulfide gas sensor using porous Cr2O3 nanomaterial as a sensitive material, comprising the following steps:

[0047] Step 1: Dissolve 1 mol of Cr(NO3)3·9H2O and 3 mol of C2H5NO2 in 20 L of deionized water, stir magnetically, and obtain a transparent and clear precursor solution;

[0048] Step 2, heating the precursor solution in an oven at 300°C for 5 hours to obtain a crude powder;

[0049] Step 3, grinding the crude powder in anhydrous ethanol, and finally drying it in an oven to obtain porous Cr2O3 nanoparticles;

[0050] Step five, evenly disperse 0.2g of porous Cr2O3 nanoparticles in 1mL of anhydrous ethanol to obtain a gas-sensitive material slurry, coat the gas-sensitive material slurry on the upper surface of the substrate with a coating thickness of 5μm, and then age it in air at 200℃ for 72h, and then set a Pt test electrode on the upper surface of the substrate and a heating electrode on the lower surface of the substrate to obtain a Cr2O3 dimethyl disulfide gas sensor 3.

[0051] Performance Test:

[0052] Figure 1 , 2 , 3 are scanning electron microscope characterization images of porous Cr2O3 nanoparticles prepared in Examples 1, 2, and 3, respectively. Figure 4The X-ray diffraction diagrams of the porous Cr2O3 nanoparticles in Examples 1-3 are characterized, wherein the curve F / O=0.75 is Example 1, the curve F / O=1.67 is Example 2, and the curve F / O=3 is Example 3.

[0053] Depend on Figure 1 and Figure 4 It can be seen that the product obtained in Example 1 is a single-phase Cr2O3, and the product presents a three-dimensional network structure formed by porous thin walls cross-linked with each other, the thin walls are relatively smooth, and there are flocculents. Figure 2 and Figure 4 It can be seen that the product obtained in Example 2 is a single-phase Cr2O3, and the product presents a porous network structure formed by porous thin walls interconnected with each other. The porous thin walls are formed by single-layer nanoparticles interconnected with each other, and the pore walls are rough. Figure 3 and Figure 4 It can be seen that the product obtained in Example 3 is a single-phase Cr2O3, and the product has a foam structure with thin walls cross-linked to form closed pores, and the thin walls are smooth.

[0054] The Cr2O3 dimethyl disulfide gas sensor prepared in Example 1-3 was placed in an air environment, and then 10 ppm of dimethyl disulfide gas molecules were introduced. The resistance change of the sensor was measured by a multimeter at 120°C, 140°C, 160°C and 180°C, and the sensor signal was obtained in turn. Figure 5 The DC resistance change response diagrams in (a), (b) and (c).

[0055] The Cr2O3 dimethyl disulfide gas sensor prepared in Example 1-3 was placed in an air environment, and then 10 ppm of dimethyl disulfide gas molecules were introduced. The response of the sensor to dimethyl disulfide gas was tested at 120°C, 140°C, 160°C and 180°C, respectively. Figure 5 (d) Response comparison diagram; Figure 5 (d) It can be seen that the three sensors have the highest response values ​​to dimethyl disulfide at an operating temperature of 140°C, and the sensor prepared in Example (2) has the highest response at an operating temperature of 140°C. This is because the porous Cr2O3 nanoparticles prepared in Example 2 have the best crystal quality and rich three-dimensional network porous structure, which is conducive to the rapid transfer of charges and the rapid penetration of gases.

[0056] The Cr2O3 dimethyl disulfide gas sensor prepared in Example 2 was placed in an air environment, and then 1ppm, 3ppm, 5ppm, 7ppm, 10ppm, 30ppm and 50ppm dimethyl disulfide gas molecules were introduced in sequence. The resistance change of the sensor was measured by a multimeter at a temperature of 140°C, and the sensor signal was obtained as follows: Figure 6Figure (a) is a DC resistance change response diagram; Figure (b) is a relationship diagram between the dynamic response of the Cr2O3 dimethyl disulfide gas sensor prepared in Example 2 and the dimethyl disulfide gas concentration; Figure (c) is a resistance dynamic change diagram of the Cr2O3 dimethyl disulfide gas sensor prepared in Example 2 in 10ppm dimethyl disulfide gas and 9 cycles at 140°C; Figure (d) is a response comparison diagram of the Cr2O3 dimethyl disulfide gas sensor prepared in Example 2 to 10ppm dimethyl disulfide, methyl sulfide, methyl mercaptan, hydrogen sulfide, carbon disulfide and sulfur dioxide and 100ppm methanol, ethanol, acetone and trimethylamine at 140°C. It can be seen from the results of the figure that the sensor has excellent repeatability and selectivity in response to 10ppm dimethyl disulfide, which can meet the requirements of dimethyl disulfide sensors for daily environmental detection.

[0057] Those skilled in the art should understand that the above are only some specific embodiments of the present invention, rather than all embodiments. It should be noted that for those of ordinary skill in the art, many modifications and improvements can be made, and all modifications or improvements that do not exceed the scope of protection of the present invention should be regarded as.

Claims

1. A dimethyl disulfide gas sensor based on porous Cr2O3 nanomaterials, characterized in that: The invention comprises a substrate, a test electrode arranged on the upper surface of the substrate and a heating electrode arranged on the lower surface of the substrate. The test electrode and the surface of the substrate where the test electrode is located are coated with porous Cr2O3 nanoparticles as a sensitive layer.

2. The dimethyl disulfide gas sensor based on porous Cr2O3 nanomaterial according to claim 1, characterized in that: The substrate is an Al2O3 substrate.

3. The dimethyl disulfide gas sensor based on porous Cr2O3 nanomaterial according to claim 1, characterized in that: The material of the test electrode is Pt or Au.

4. The dimethyl disulfide gas sensor based on porous Cr2O3 nanomaterial according to claim 1, characterized in that: The thickness of the gas-sensitive material is 0.5 μm-20 μm.

5. The dimethyl disulfide gas sensor based on porous Cr2O3 nanomaterial according to claim 1, characterized in that: The particle size of the porous Cr2O3 nanoparticles is 10nm-100nm.

6. The dimethyl disulfide gas sensor based on porous Cr2O3 nanomaterial according to any one of claims 1 to 5, characterized in that: When the sensor is used to monitor dimethyl disulfide gas, the sensitive layer is heated to 20-200° C. by heating the electrode.

7. A method for preparing a dimethyl disulfide gas sensor based on porous Cr2O3 nanomaterials according to any one of claims 1 to 6, characterized in that: The steps include: S1. Evenly dispersing porous Cr2O3 nanoparticles with a particle size of 10 nm to 100 nm in anhydrous ethanol to obtain a gas-sensitive material slurry; S2. Coat the gas-sensitive material slurry on the upper surface of the substrate with a coating thickness of 0.5 μm-20 μm, place it in air for aging, then set a test electrode on the upper surface of the substrate and a heating electrode on the lower surface of the substrate to obtain a Cr2O3 dimethyl disulfide gas sensor.

8. The method for preparing a dimethyl disulfide gas sensor based on porous Cr2O3 nanomaterial according to claim 7, characterized in that: The dispersion concentration of the porous Cr2O3 nanoparticles in the gas-sensitive material slurry is 0.05g-0.3g / ml.

9. The method for preparing a dimethyl disulfide gas sensor based on porous Cr2O3 nanomaterial according to claim 7, characterized in that: In step S2, the substrate coated with the gas-sensitive material slurry is placed in air at 150-450° C. for aging for 12-168 hours.

10. The method for preparing a dimethyl disulfide gas sensor based on porous Cr2O3 nanomaterial according to claim 7, characterized in that: The preparation method of the porous Cr2O3 nanoparticles is as follows: S11, weigh glycine C2H5NO2 and chromium nitrate nonahydrate Cr(NO3)3·9H2O in a molar ratio of (0.75-3.0):1, dissolve them in deionized water in sequence, the chromium ion concentration is 0.05M-0.5M, and obtain a transparent and clear precursor solution; S12, heating the precursor solution in an oven at 300-500° C. for 0.2-5.0 h to obtain a crude powder; S13. Grind the crude powder in anhydrous ethanol and dry it to obtain porous Cr2O3 nanoparticles with a particle size of 10nm-100nm.

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