Benzene-series VOC gas room temperature sensor and preparation method thereof

Abstract

The invention belongs to the technical field of detection of benzene-series volatile organic compounds, and particularly relates to a benzene-series VOC gas room temperature sensor and a preparation method thereof. The method comprises the following specific steps: S1, sequentially centrifuging, collecting and dispersing a gold nanoparticle colloidal solution in ethanol to obtain a mixed solution 1; the preparation method comprises the following steps: preparing a gold nanoparticle modified solution, dissolving 2, 6-naphthalene dithiol in ethanol to obtain a mixed solution 2, incubating under a water bath condition, obtaining a modified compound after the color of the solution becomes black, centrifuging and washing, and finally dispersing in ethanol to obtain the modified gold nanoparticle modified solution; and S3, dispensing the gold nanoparticle modification solution on a substrate with two electrodes to form a gold nanoparticle modification layer of 200 nm to 10 [mu] m, and drying at room temperature to obtain the sensor. The benzene VOC gas sensor disclosed by the invention can respond at room temperature and has high selectivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of detection of benzene-based volatile organic compounds, and in particular relates to a benzene-based VOC gas room temperature sensor and a preparation method thereof. Background Art

[0002] In recent years, with the acceleration of industrialization, emissions of volatile organic compounds (VOCs) have become increasingly severe, causing serious impacts on the environment and human health. Benzene-based VOCs, as typical toxic VOCs, have attracted widespread attention due to their high volatility and strong carcinogenicity. Benzene-based VOC gas sensors based on resistance measurement are highly favored due to their advantages such as miniaturization, low power consumption, and ease of integration. For example, gas sensors based on metal oxide semiconductor (MOS) materials have been widely studied, and materials such as SnO2, ZnO, and In2O3 have shown certain responses in benzene detection.

[0003] However, conventional resistor-based benzene VOC gas sensors are implemented using semiconductor materials, which require high operating temperatures (typically exceeding 200°C). This not only increases energy consumption but also poses safety risks such as explosions or fires. Furthermore, these sensors have poor selectivity and are easily interfered with by other gases, making accurate detection difficult in complex environments. Summary of the Invention

[0004] In order to overcome the above-mentioned defects in the prior art, the present invention provides a benzene-based VOC gas room temperature sensor and a preparation method thereof. The benzene-based VOC gas sensor of the present invention can respond at room temperature and has high selectivity.

[0005] To achieve one of the above purposes, the present invention adopts the following technical solutions:

[0006] A method for preparing a benzene-based VOC gas room temperature sensor, the specific steps are as follows:

[0007] S1, centrifuging, collecting, and dispersing the gold nanoparticle colloidal solution in ethanol to obtain a mixed solution 1, wherein the volume ratio of the gold nanoparticle colloidal solution to ethanol is 5:(2-10); and dissolving 2,6-naphthalenedithiol in ethanol to obtain a mixed solution 2;

[0008] S2, mixing the mixed solution 1 and the mixed solution 2, and incubating them in a water bath until the solution turns black to obtain a modified complex, which is then centrifuged and washed, and finally dispersed in ethanol to obtain a modified gold nanoparticle modification solution;

[0009] S3. Drop the gold nanoparticle modification solution onto the substrate with two electrodes to form a 200nm-10um gold nanoparticle modification layer, and then dry it at room temperature to obtain a sensor.

[0010] Preferably, the concentration of the gold nanoparticle colloidal solution is 10 mM-1000 mM; the concentration of the mixed solution 2 is 10 mM-100 mM.

[0011] Preferably, in step S2, the water bath temperature is 20-80°C, preferably 40°C.

[0012] Preferably, in step S2, the incubation time is 2-24 hours, preferably 24 hours.

[0013] Preferably, in step S2, the modified complex is centrifuged and washed with ethanol to remove excess 2,6-naphthalenedithiol, with a centrifugal speed of 5000-1000 rpm and a time of 5-15 min.

[0014] Preferably, in step S2, the volume ratio of the mixed solution 1 to the mixed solution 2 is 1:1; and the modified complex is dispersed in 1 ml of ethanol.

[0015] Preferably, the electrode is a gold electrode, and the substrate is ceramic or glass.

[0016] Preferably, the preparation method of the gold nanoparticle colloidal solution is as follows: 100 mL of ultrapure water is added to a round-bottom flask, heated to boiling, and then 0.5 mL to 1.5 mL of a 1% chloroauric acid solution is added. After continuing to heat for 30 minutes, 0.5 mL to 3 mL of a 1% sodium citrate solution is added. After continuing to heat for 30 minutes, the solution is cooled to room temperature to generate a colloidal solution of gold nanoparticles with a size of 30 nm to 60 nm and excellent dispersion.

[0017] To achieve the second of the above objectives, the present invention provides a benzene-based VOC gas room temperature sensor, which includes a substrate on which a gold nanoparticle modification layer is deposited, and two electrodes are provided on the substrate, and the two sides of the gold nanoparticle modification layer are respectively connected to the two electrodes.

[0018] Preferably, the gold nanoparticle modification layer is obtained by modifying gold nanoparticles with 2,6-naphthalenedithiol.

[0019] The advantages of the present invention are:

[0020] The present invention uses 2,6-naphthalenedithiol modified gold nanoparticle film as the key sensitive material to construct a sensor, and achieves highly selective sensing at room temperature and ultra-sensitive detection of benzene series by detecting the resistance of the modified gold nanoparticle film. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention.

[0022] Figure 2This is a scanning electron microscope image of the 2,6-naphthalenedithiol-modified gold nanoparticles of the present invention.

[0023] Figure 3 This is the test curve of the sensor of the present invention responding to benzene vapor at different concentrations.

[0024] Figure 4 This is the test curve of the sensor of the present invention responding to other benzene-based VOC gases (all at 100 ppm).

[0025] The meanings of the symbols in the figure are as follows:

[0026] 1-substrate, 2-electrode, 3-gold nanoparticle modification layer. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0028] like Figure 1 As shown, a benzene-based VOC gas room temperature sensor, the core of which is 2,6-naphthalenedithiol molecules modified with gold nanoparticles to form a gold nanoparticle modification layer 2. The gold nanoparticle modification layer is supported by a ceramic sheet as a substrate 1. Two gold electrodes 1 are connected to both sides of the gold nanoparticle modification layer 2 for collecting electrical signals.

[0029] A method for preparing a benzene-based VOC gas room temperature sensor, the specific steps are as follows:

[0030] S1. Centrifuging a 10 mM to 1000 mM gold nanoparticle colloidal solution, collecting the solution, and dispersing the solution in ethanol to obtain a mixed solution 1, wherein the volume ratio of the gold nanoparticle colloidal solution to ethanol is 5:(2-10); and dissolving 10 mM to 100 mM 2,6-naphthalenedithiol in ethanol to obtain a mixed solution 2, wherein the concentration of the mixed solution 2 is 10 mM to 100 mM.

[0031] S2, mixing the mixture 1 and the mixture 2 in a volume ratio of 1:1, and incubating in a water bath at 20-80° C. for 2-24 hours. After the solution turns black, a modified complex is obtained. The modified complex is then centrifuged and washed with ethanol. Finally, the modified complex is dispersed in 1 ml of ethanol to obtain a modified gold nanoparticle modification solution.

[0032] S3. Drop the gold nanoparticle modification solution onto a ceramic sheet with two gold electrodes to form a 200nm-10um gold nanoparticle modification layer, and then dry it at room temperature to obtain a sensor.

[0033] The preparation method of the gold nanoparticle colloidal solution is as follows: 100 mL of ultrapure water is added to a round-bottom flask, and after heating to boiling, 0.5 mL to 1.5 mL of a 1% chloroauric acid solution is added. After continuing to heat for 30 minutes, 0.5 mL to 3 mL of a 1% sodium citrate solution is added. After continuing to heat for 30 minutes, the solution is cooled to room temperature to generate a colloidal solution of 30 nm to 60 nm gold nanoparticles.

[0034] Example 1

[0035] 1. 5 ml of gold nanoparticle colloidal solution was centrifuged, collected, and dispersed in 5 ml of ethanol. It was then mixed with 2 ml of a 20 mM 2,6-naphthalenedithiol solution pre-dissolved in 100 ul of ethanol and incubated in a water bath at 40°C for 24 hours. Subsequently, the solution was centrifuged and washed with ethanol several times, and finally dispersed in 1 ml of ethanol solution to prepare a gold nanoparticle modified solution. The modified gold nanoparticles in the gold nanoparticle modified solution were scanned by electron microscopy, as shown below. Figure 2 The scanning electron microscope photo shown in the figure shows that the white part in the middle is gold nanoparticles, and the outer layer wrapped around the outside of the gold nanoparticles is 2,6-naphthalenedithiol.

[0036] 2. The gold nanoparticle modification solution prepared above was applied to the surface of the ceramic sheet to form a 2 μm gold nanoparticle modification layer by drop coating, and the gas sensor was prepared after drying at room temperature.

[0037] Sensor component assembly and testing

[0038] 1. Install the prepared gas sensor in a sealed test chamber and connect the prepared gas sensor to the circuit;

[0039] 2. Introduce benzene vapor and use electrical testing instruments to detect changes in conductivity;

[0040] 3. The data acquisition system collects and analyzes the signal, and the results are as follows: Figure 3 As shown, the experimental results show that Figure 3 It can be seen that the resistance changes with the passage of time and the change of benzene vapor concentration in the environment, and the sensor can still produce a significant signal response at the 1ppb concentration level, verifying the high sensitivity of the detection mechanism. Figure 4 As shown, the sensor can also respond well to different benzene-based VOC gases (including xylene, styrene, ethylbenzene, toluene, chlorobenzene, etc.).

[0041] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a benzene-based VOC gas room temperature sensor, characterized in that: The specific steps are as follows: S1, centrifuging, collecting, and dispersing the gold nanoparticle colloidal solution in ethanol to obtain a mixed solution 1, wherein the volume ratio of the gold nanoparticle colloidal solution to ethanol is 5:(2-10); and dissolving 2,6-naphthalenedithiol in ethanol to obtain a mixed solution 2; S2, mixing the mixed solution 1 and the mixed solution 2, and incubating them in a water bath until the solution turns black to obtain a modified complex, which is then centrifuged and washed, and finally dispersed in ethanol to obtain a modified gold nanoparticle modification solution; S3. Drop the gold nanoparticle modification solution onto the substrate with two electrodes to form a 200nm-10um gold nanoparticle modification layer, and then dry it at room temperature to obtain a sensor.

2. The method for preparing a benzene-based VOC gas room temperature sensor according to claim 1, characterized in that: The concentration of the gold nanoparticle colloidal solution is 10mM-1000mM; the concentration of the mixed solution 2 is 10mM-100mM.

3. The method for preparing a benzene-based VOC gas room temperature sensor according to claim 1, characterized in that: In step S2, the water bath temperature is 20-80°C.

4. The method for preparing a benzene-based VOC gas room temperature sensor according to claim 1, wherein: In step S2, the incubation time is 2-24 hours.

5. The method for preparing a benzene-based VOC gas room temperature sensor according to claim 1, characterized in that: In step S2, the modified complex is washed by centrifugation using ethanol at a speed of 5000-1000 rpm for 5-15 minutes.

6. The method for preparing a benzene-based VOC gas room temperature sensor according to claim 1, wherein: In step S2, the volume ratio of the mixed solution 1 to the mixed solution 2 is 1:1; and the modified complex is dispersed in 1 ml of ethanol.

7. The method for preparing a benzene-based VOC gas room temperature sensor according to claim 1, characterized in that: The electrode is a gold electrode, and the substrate is ceramic or glass.

8. The method for preparing a benzene-based VOC gas room temperature sensor according to claim 1, characterized in that: The preparation method of the gold nanoparticle colloidal solution is as follows: 100 mL of ultrapure water is added to a round-bottom flask, and after heating to boiling, 0.5 mL to 1.5 mL of a 1% chloroauric acid solution is added, and heating is continued for 30 minutes. Then, 0.5 mL to 3 mL of a 1% sodium citrate solution is added, and heating is continued for 30 minutes. After cooling to room temperature, a colloidal solution of 30 nm to 60 nm gold nanoparticles is generated.

9. A benzene-based VOC gas room temperature sensor prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The sensor comprises a substrate (1), a gold nanoparticle modification layer (3) is deposited on the substrate (1), two electrodes (2) are provided on the substrate (1), and two sides of the gold nanoparticle modification layer (3) are respectively connected to the two electrodes (2).

10. The benzene-based VOC gas room temperature sensor according to claim 8, characterized in that: The gold nanoparticle modification layer (3) is obtained by modifying gold nanoparticles with 2,6-naphthalenedithiol.

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