KR20220048652A - HIGHLY SENSITIVE NITROGEN DIOXIDE (NO2) GAS SENSOR USING GRAPHENE DOPED WITH ZINC OXIDE (ZnO) NANOSHEET, AND A METHOD FOR MANUFACTURING THE SAME - Google Patents

Abstract

Disclosed are a nitrogen dioxide (NO_2) gas detection sensor, and a method for manufacturing the same.

Description

HIGHLY SENSITIVE NITROGEN DIOXIDE (NO2) GAS SENSOR USING GRAPHENE DOPED WITH ZINC OXIDE (ZnO) NANOSHEET, AND A METHOD FOR MANUFACTURING SAME}

The present specification relates to a high-sensitivity nitrogen dioxide gas sensor using graphene doped with a zinc oxide nanosheet and a method for manufacturing the same.

More specifically, it is possible to optimize the doping concentration, characteristics of zinc oxide nanosheets, and nitrogen dioxide gas detection conditions, and to detect through resistance changes when nitrogen dioxide gas is in contact with the graphene surface. It relates to a nitrogen dioxide gas detection sensor and a method for manufacturing the same.

Nitrogen dioxide (NO ₂ ) gas is considered a hazardous air pollutant as one of the combustion products and as a precursor to the formation of smog, fine dust and acid rain. In addition, it has a serious adverse effect on human health. Therefore, it is important to monitor the concentration of NO ₂ gas to evaluate air quality, and many studies have been conducted to develop several types of NO ₂ gas sensors that are commercially available, convenient and easy to use.

From a safety point of view, room temperature (RT) detection of NO ₂ gas is required, especially in explosive environments. Numerous metal oxides and metal oxides for semiconductor reforming have been applied to materials for NO ₂ gas detection.

However, currently available metal oxide semiconductor-based sensors cannot detect with high sensitivity at room temperature. Therefore, manufacturing a material for sensor measurement at room temperature suitable for a NO ₂ gas sensor still remains a difficult problem to solve.

Graphene is widely used in various fields including sensors. In order to be applied as a gas sensor, it must have several important characteristics. First, the gas must be exposed on all surfaces, and secondly, the thermal noise must be low. Third, it must be very stable in the atmosphere and in harsh environments. However, graphene is not suitable to satisfy these conditions.

Therefore, by doping various nanostructures made of transition metals on the graphene surface, it is possible to improve the disadvantages of graphene and use it as a sensor.

Pristine graphene and metal oxides have considerable promise and promise as ideal materials for the detection of NO ₂ gas due to their low cost, excellent electrical properties and high surface-volume ratio at room temperature. .

However, metal oxides cannot be easily grown on graphene because of their high curvature and poor solubility in water, ethanol and other polar organic solvents. It is necessary to develop a nitrogen dioxide detection sensor that can overcome this problem and has high sensitivity and high selectivity.

Korean Patent Registration No. 10-2090489

For example, the ammonia gas detection sensor described in the patent document of FIG. 12 is configured by placing a detection sensor doped with copper oxide nanoparticles on a circular graphene surface on a substrate, as shown. The existing gas detection sensor is an electrochemical measurement sensor by oxidation/reduction. The sensor is sensitive to heat, so there are restrictions on use depending on the environment, reproducibility and sensitivity due to oxidation of metal components are low, and there are many restrictions on application, so there are many problems in using such a sensor in the field.

In the present specification, by preparing and doping a zinc oxide nanosheet on the surface of a pristine graphene of a chemical single layer, nitrogen dioxide (NO ₂ ) gas, which is a target for their physicochemical properties and detection It is intended to provide a high-sensitivity, high-performance real-time detection sensor through resistance change.

In addition, in the present specification, real-time monitoring of nitrogen dioxide gas by modifying the material and chemical properties of the graphene surface using a nanostructure material made of zinc oxide nanosheets made of an oxide of zinc (Zn), which is a transition metal It provides an efficient, simple manufacturing process, high-sensitivity, high-performance sensor development and a manufacturing method for the same.

In one embodiment of the present invention, a substrate; a graphene sheet positioned on the substrate; and a zinc oxide nanosheet doped on the graphene sheet; It provides a nitrogen dioxide gas detection sensor comprising a.

In another embodiment of the present invention, manufacturing a zinc oxide nanosheet (ZnO nanosheet); and doping the zinc oxide nanosheet on the graphene sheet.

In another embodiment of the present invention, the above-described nitrogen dioxide gas detection sensor; chamber; control and recording devices; flow control device; and a gas supply device; it provides, including, a nitrogen dioxide gas detection system.

The nitrogen dioxide gas detection sensor according to an embodiment of the present invention includes graphene in which a nanosheet is doped in a single layer or in multiple layers by doping a thin nanosheet-type zinc oxide on a graphene surface, wherein the doped graphene Fins are an important base material for gas sensors. In addition, the properties of graphene suggest optimal conditions for high-sensitivity nitrogen dioxide gas detection by changing the layer or controlling the concentration of zinc oxide nanosheets.

In addition, the nitrogen dioxide gas detection sensor according to an embodiment of the present invention is a detection sensor using a nanostructure material made of an oxide of a transition metal with high sensitivity and high selectivity. (10-100 ppm) section, that is, it is possible to detect the target gas in a wide range of about 0.001 to 500 ppm.

1 is a conceptual diagram schematically illustrating an operating mechanism of a nitrogen dioxide (NO ₂ ) gas detection sensor according to an embodiment of the present invention.
2 is a series of processes illustrating a method for manufacturing a nitrogen dioxide gas detection sensor according to an embodiment of the present invention.
3 is a schematic conceptual diagram of a graphene phase of a nitrogen dioxide gas detection sensor according to an embodiment of the present invention.
4 is an overall configuration diagram of a nitrogen dioxide gas detection system according to an embodiment of the present invention.
5 is a graph showing the reactivity of the electrical conduction resistance according to the doping number of zinc oxide of the nitrogen dioxide gas detection sensor according to an embodiment of the present invention.
6A-6D are TEM photographs (6A-C) of graphene doped with zinc oxide in the nitrogen dioxide gas detection sensor according to an embodiment of the present invention, and a size distribution diagram of zinc oxide nanosheets measured with a Zetasizer ( 6D).
7a-7c are graphene (b) doped with initial graphene (a) and zinc oxide nanosheets in the nitrogen dioxide gas detection sensor according to an embodiment of the present invention, and its G band (7B) and 2D band ( 7C) is a Raman spectrum showing the difference (frequency and intensity change).
8 is a graph showing (A) circular graphene, (B) graphene doped with zinc oxide nanosheets, and prepared zinc oxide nanosheet powder ( C) is the XRD spectrum.
9A-9B are graphs showing the reactivity and stability of a sensor doped with zinc oxide nanosheets at 100 ppm of nitrogen dioxide gas in the nitrogen dioxide gas detection sensor system according to an embodiment of the present invention.
10A-10B are a graph 10A and a quantitative graph 10B showing the reactivity according to the nitrogen dioxide gas concentration in the nitrogen dioxide detection system according to an embodiment of the present invention.
11 is a graph showing gas reactivity to nitrogen dioxide gas, sulfuric acid gas, hydrogen sulfide, ammonia, dimethyl sulfide (demethy sulfide), and acetaldehyde in the nitrogen dioxide gas detection system according to an embodiment of the present invention.
12 schematically shows another conventional gas detection sensor.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Embodiments of the present invention have been described with reference to the accompanying drawings, which are described for purposes of illustration, and the technical spirit of the present invention and its configuration and application are not limited thereby.

Prior to the description, in various embodiments, the same reference numerals are used to denote components having the same configuration in one embodiment, and only other components will be described in other embodiments.

Exemplary embodiments of the present invention include a substrate; a graphene sheet positioned on the substrate; and a zinc oxide nanosheet doped on the graphene sheet; It provides a nitrogen dioxide gas detection sensor comprising a.

1 is a conceptual diagram schematically illustrating an operating mechanism of a nitrogen dioxide gas detection sensor according to an embodiment of the present invention.

As shown in FIG. 1, the nitrogen dioxide gas detection sensor 10 is doped on the surface of the substrate 11, the graphene sheet 12 and the graphene sheet 12 positioned on the upper portion of the substrate 11. and zinc oxide nanosheets (13). In particular, the nitrogen dioxide gas sensor 10 according to an embodiment of the present invention is useful for detecting gaseous nitrogen dioxide (NO ₂ ) gas.

Referring to FIG. 1 , the initial graphene exposure in the environment induces p-type doping due to free electron trapping by oxygen ions, water vapor and other contaminants.

The nitrogen dioxide sensing mechanism of doped graphene can be explained by the adsorption and reaction sites provided by the graphene dopant. When interacting with the zinc oxide nanosheets on the graphene surface, nitrogen dioxide molecules oxidize zinc and convert it into zinc oxide (ZnO), that is, a p-type semiconductor.

This response changes the concentration of charge carriers in the sensor's conduction channel. Since graphene in air is a p-type semiconductor, if a hole by ZnO is added, the resistivity decreases and the presence of nitrogen dioxide gas can be detected. Currently, the observed sensing behavior of resistive ZnO nanosheet-based graphene sensors can be explained based on charge transfer and surface reaction mechanisms. The circuit diagram in FIG. 1 specifically shows the sensing mechanism and surface properties of the graphene-ZnO nanosheet composite sensor for NO ₂ . The graphene-ZnO nanosheet composite synthesized by chemical reduction has p-type semiconductor properties due to the electron-withdrawing oxygen functional group.

Interestingly, even after doping of the graphene-ZnO nanosheet composite, it still behaves like a typical p-type semiconductor.

Conductivity appears to be due to the hole. When exposed to electrons withdrawing oxidized NO ₂ , the hole concentration on the surface of the ZnO-graphene composite increases due to the transfer of electrons from the graphene surface to adsorbed NO ₂ molecules. As a result, the hole conductivity also increases, resulting in a decrease in resistance.

The working principle of the ZnO gas sensor is based on the change in electrical resistivity/conductivity due to adsorption desorption and charge transfer of the gas depending on the composition and operating temperature of the gas and the doped metal composition and composition.

Under normal atmospheric conditions, ZnO is O ^- , O ² - and O ₂ ^- Oxygen is absorbed from the air, and the adsorbed oxygen lifts electrons from the surface of the ZnO nanosheet to form an electron-depleted surface layer. This forms a narrow conduction channel.

In addition, the presence of an oxidizing gas such as nitrogen dioxide in the experimental chamber will lift more electrons from the surface of the ZnO ZnO nanosheets.

This increases the thickness of the depletion region, resulting in a smaller conduction channel. As a result, the reduced conduction channel results in a measurable change in the resistance of the ZnO nanosheet sample.

In addition, in the case of the present invention, zinc oxide nanosheets (ZnO nanosheets) as nanoparticles provide an effective surface area for gas diffusion, and thus play an important role in sensing performance.

In one embodiment, the substrate may be Si coated with SiO ₂ .

The graphene sheet 12 means that the graphene material is formed as a thin film layer, and it is preferable to use the graphene sheet 12 of a mono-layer.

In one embodiment, the graphene sheet may be formed of a single layer.

In addition, the nitrogen dioxide gas detection sensor 1 according to an embodiment of the present invention means that the zinc oxide nanosheet 13 is doped on the upper surface of the graphene sheet 12, and this zinc oxide nanosheet is It does not have a specific direction or rule on the upper surface of the fin sheet 12 , and is evenly distributed on the upper surface of the graphene sheet 12 .

In one embodiment, the zinc oxide nanosheet (ZnO nanosheet) may be formed of a single layer (mono-layer) or two or more layers (multi-layer). Graphene doped with zinc oxide nanosheets has strong mechanical and electrical properties and stability of graphene.

The zinc oxide nanosheet has improved charge storage and transport characteristics compared to other nanostructures or bulk particles other than the nanosheet, and can provide many active sites by improving the surface area.

In one embodiment, the average size of a single particle of the zinc oxide nanosheet (ZnO nanosheet) may be 50 to 90 nm, for example, 60 to 80 nm, or preferably about 75 nm. The average size represents the average value of the longest length on the plane of the plate-shaped structure of the zinc oxide nanosheet single particles.

In one embodiment, when the single particles of the zinc oxide nanosheet (ZnO nanosheet) are aggregated, the average size may be 300 to 500 nm, for example, 350 to 450 nm, or preferably about 400 nm.

In one embodiment, the doping may be performed by spin coating a zinc oxide nanosheet (ZnO nanosheet) on the graphene sheet 4 to 6 times, preferably by spin coating 5 times, more preferably For example, when the concentration of the zinc oxide nanosheet 13 is 0.122 mol, doping may be performed by spin coating 5 times.

In one embodiment, the nitrogen dioxide gas detection sensor may detect nitrogen dioxide gas within 150 seconds.

In one embodiment, the nitrogen dioxide gas detection sensor may detect nitrogen dioxide gas at 20 to 35 ℃.

The nitrogen dioxide gas detection sensor can detect nitrogen dioxide gas at 0.001 to 1,000 ppm, for example, when the nitrogen dioxide concentration is 0.001 to 700 ppm, 0.01 to 600 ppm, or 0.1 to 500 ppm, nitrogen dioxide gas can be detected.

In one embodiment, the nitrogen dioxide gas detection sensor, electrodes connected to both ends of the graphene sheet; and a power supply unit for driving the nitrogen dioxide gas detection sensor.

2 is a series of processes illustrating a method for manufacturing a nitrogen dioxide gas detection sensor according to an embodiment of the present invention.

In another exemplary embodiment of the present invention, the method comprising the steps of: manufacturing a zinc oxide nanosheet (ZnO nanosheet); and doping the zinc oxide nanosheet on the graphene sheet.

In one embodiment, in the step of doping the zinc oxide nanosheet (ZnO nanosheet) on the graphene sheet, the graphene sheet is immersed in a solution containing a zinc oxide nanosheet (ZnO nanosheet), and the mixture solution may be performed by spin coating at a speed of 900 to 1100 rpm for 200 to 400 seconds.

In one embodiment, the spin coating may be performed 4 to 6 times.

In one embodiment, the concentration of the solution containing the zinc oxide nanosheet (ZnO nanosheet) may be 20 μL to 140 μL, for example, 30 to 130 μL or preferably 100 μL, more preferably 0.122 100 μl of M.

In another exemplary embodiment of the present invention, the above-described nitrogen dioxide gas detection sensor; chamber; control and recording devices; flow control device; and a gas supply device; it provides, including, a nitrogen dioxide gas detection system.

In one embodiment, Figure 4 is an overall configuration diagram of the nitrogen dioxide gas detection system according to an embodiment of the present invention.

Referring to FIG. 4 , nitrogen oxide gas and argon gas are mixed through the gas supply device 60 so that the flow rate of the nitrogen dioxide gas can determine a concentration gradient through the mass flow controller (MFC) 50 equipment, and the chamber 20 ) reacts with the sensor 10 to measure the resistance value of the multimeter 30 equipment, and the measured value may be displayed on the PC 40 .

Hereinafter, the present invention will be described in detail with reference to preferred embodiments so that those skilled in the art can easily carry out the present invention. However, the present invention may be implemented in various different forms, and is not limited to the embodiments described herein.

< Example 1> Zinc Oxide nanosheet ( nanosheet ) Produce

To prepare ZnO nanosheets, 3.30 g (0.015 mol) of zinc acetate dihydrate (Zn(CH ₃ COO) ₂ )·2H ₂ O) and 6.00 g (0.15 mol) of sodium hydroxide (NaOH) were mixed with 25 ml of It was dissolved in distilled water and re-sorted.

Then, the aqueous solution was mixed with vigorous stirring at 0° C., and then 100 mL of sodium citrate solution (trisodiumcitrate) (0.5 M) was slowly added to the mixture. The temperature was then raised to 90 °C and held for 1 h. The clear solution gradually became opaque at about 75 °C, reflecting the growth of zinc oxide nanosheet crystals.

After the reaction, the white powder was killed by vacuum filtration, washed several times with distilled water and methanol, and dried at room temperature for 1 day.

In the finally produced ZnO nano sheet powder, the atomic percent was found to be Zn 46.15% O 53.85%.

< Example 2> Zinc Oxide ZnO nanosheet used graphene sensor manufacturing

First, a graphene sheet was laminated on a SiO ₂ /Si substrate using the method described in FIG. 3 of Korean Patent Registration No. 10-1957460. Specifically, pristine graphene from graphene laboratories inc was purchased and applied by doping zinc oxide. (Single Layer CVD Graphene on 285 nm SiO ₂ /silicon (p-doped) 1 cm X 1 cm)

To manufacture the nitrogen dioxide gas sensor, graphene was spin-coated with zinc oxide nanosheets. Doping the prepared zinc oxide nanosheet solution onto graphene. Specifically, as shown in FIG. 2, 20 μL drops of 10 mg/ml (0.122 M) (Etanol) solution of zinc oxide powder were spin-coater on the graphene. The coating is carried out for 300 seconds at a speed of 1000 rpm while being immersed 1 to 7 times in a drop. Then, the sample was heated in an oven at 100 °C for 30 minutes to remove all volatile organic contaminants. After heating, the prepared zinc oxide nanosheet (ZnO nanosheet) and graphene composite were cooled for 1 hour and then mounted on a plastic framework. is connected to the electrode.

< Example 3> Nitrogen dioxide (NO ₂ ) gas detection measuring equipment

3 is a schematic conceptual diagram of a graphene phase of a nitrogen dioxide gas detection sensor according to an embodiment of the present invention. It can be used as a nitrogen dioxide gas detection sensor by forming a single layer of graphene, doping the upper part using a zinc oxide nanosheet, and grounding the silver paste.

The graphene sensor of the present invention was developed based on an electrochemical measuring device due to its design simplicity and high sensitivity. It consists of circular graphene doped on a SiO ₂ /Si substrate and serves as a sensing material to bridge the gap between two silver electrodes.

4 is an overall configuration diagram of a nitrogen dioxide gas detection system according to an embodiment of the present invention.

The nitrogen dioxide gas 60 is mixed with argon gas so that the flow rate of the nitrogen dioxide gas can determine a concentration gradient through the mass flow controller (MFC) 50 equipment, and the sensor 10 in the chamber 20 reacts with the multimeter ( 30) The resistance value (resistance) of the equipment was measured, and the measured value was displayed on the PC (40).

The total gas flow rate was maintained at 5 L/min. In the nitrogen dioxide gas detection experiment, the sensor was initially exposed to the atmosphere to reach the reference resistance and stabilized, then exposed to the target gas and measured. After that, the chamber was opened in the absence of gas detection for gas removal and rapid recovery.

The intrinsic resistance of the electrochemical measuring device could be controlled by exposure to the analyte gas in proportion to the concentration of gas molecules. Thus, the concentration of nitrogen dioxide was quantified by measuring the change in relative resistance as a function of time. Relative sensor response (Response, R) was expressed as a percentage as in Equation 1:

[Equation 1]

R(%) = (Rr-Ri) / Ri × 100%

where Rr is the resistance of the sensor measured in the presence of nitrogen dioxide gas, and Ri is the initial sensor resistance in the absence of the analyte gas.

< Example 4> Nitrogen dioxide gas sensor characterization

An experiment was conducted to establish conditions for optimal nitrogen dioxide gas detection in the nitrogen dioxide gas detection sensor and system.

5 is a graph showing the reactivity according to the doping amount of the zinc oxide nanosheet of the nitrogen dioxide gas detection sensor according to an embodiment of the present invention.

As shown in FIG. 5, 20 μL of the zinc oxide (0.122 M) nanosheet prepared in Example 1 was spin-coated 1 to 7 times, and then the reactivity of the sensor was measured. As shown in FIG. 5, it can be seen that the sensor coated with 5 times is about 2.3 times superior to the sensor coated with 1 time in reactivity.

6A-6D are photographs of graphene (6A-C) doped with zinc oxide nanosheets in the nitrogen dioxide gas detection sensor according to an embodiment of the present invention, and a size distribution diagram (6D) of zinc oxide nanosheets measured with a Zetasizer; )am.

Zinc oxide nanosheets are not perfectly flat, but exhibit intrinsic microstructural changes and planar deformations (wrinkles). As shown in FIG. 6(A, B), the average diameter of the zinc oxide nanosheets doped on graphene was about 75 nm. It can be seen that this is consistent with the particle distribution of the zinc oxide nanosheets of FIG. 6(D). However, the size of the nanosheets due to the aggregation of the zinc oxide nanosheets can be confirmed to be about 400 nm.

The HR-TEM image in Fig. 6(C) shows the intimate contact between ZnO and graphene. The lattice distances of the molecular structure arrangement of adjacent zinc oxide nanosheets are about 0.54 nm and 0.276 nm, which is in the order of the distances in the {001}, {100} and {002} planes of the ZnO wurtzite structure. corresponds to Specifically, the SAED (Selected Area Electron Diffraction) pattern of the TEM equipment suggests an index capable of calculating d-spacing with the selected area electron difference pattern. Specifically, it can be seen which part is being observed through a bright field, how the molecules are oriented in the specimen in the observed area, and the brighter the crystal, the more it can be confirmed that it is a particle. As a result of observation with such equipment, it can be confirmed that the structure of the zinc oxide nanosheet of the present invention is a single crystal plate-like structure.

Such intimate contact enables electronic interaction between ZnO and graphene, and is thought to enhance charge separation and gas detection activity.

7a-7c are graphene (b) doped with initial graphene (a) and zinc oxide nanosheets, and G band (7B) and 2D band (7B) and 2D band ( 7C) is a Raman spectrum showing the change in frequency and peak intensity.

As shown in Fig. 7, Raman spectroscopy has been widely used for doping characterization because both the G and 2D bands are strongly affected by the charge carrier concentration. Therefore, by characterizing the sp ² carbon disorder in graphene, it provided important information on the physical property change of graphene doped with early graphene and zinc oxide nanosheets (ZnO nanosheets).

In general, the D band (1350 nm ^{- 1} ) indicates a defect on the graphene, and when a peak is formed in the D band, it can be seen that the defects on the graphene surface are increased. And the properties of the 2D and G bands (I _2D /I _G ) are determined according to the growth of graphene by the ratio between the peak intensities. The graphene-ZnO nanosheet shows that the frequency value of the 2D band is upshifted and the I _2D /I _G value is 1.40, which is decreased compared to 1.59 of the circular graphene, which is the case of the graphene-ZnO nanosheet composite. It has multi-layer properties, which is due to graphene doping of zinc oxide nanosheets.

Figure 8 is in the nitrogen dioxide gas detection sensor according to an embodiment of the present invention, circular graphene (pristine graphene) (A) and zinc oxide nanosheet (ZnO nanosheet) doped graphene (B) and produced oxide It is an XRD graph of a zinc nanosheet (C).

As shown in FIG. 8, the X-ray diffraction patterns for circular graphene, graphene doped with ZnO nanosheets, and ZnO nanopowder show scattering angle peaks of about 31.7°, 34.3°, 36.3°, 47.6°, and 56.5°. , 63.0°, 66.5°, 67.9°, 69.1° to [100] [002], [101], [102], [110], [103], [200], [112] and [201] to planar ZnO (JCPDS No. 36-1451) can be confirmed.

In the diffraction diagram of pristine graphene, the most intense peak (001) centered at about 2θ = 10.6° is due to the presence of oxygen carriers on the graphene surface. This peak was significantly reduced in graphene doped with zinc oxide nanosheets.

< Example 5> Nitrogen dioxide gas detection sensor responsiveness, reproducibility, quantitative , selectivity check

The response of the sensor as a function of the nitrogen dioxide gas concentration was measured according to the 100 ppm concentration (Fig. 9(B)), as shown in Fig. 9(A). Initially, after the gas reaction, the R value was about 33.8. %, and the R values for the second to fourth times after recovery were 32.8% to 30.50%, respectively, which corresponded to 90% to 97% of the initial value, and the standard deviation was within 3.5%. , it can be confirmed that the sensor of the present invention has very good reproducibility for nitrogen dioxide regardless of the reaction time.

In addition, the sensitivity and quantification can be confirmed in FIGS. 10A-10B . The reaction degree of the sensor was measured at a nitrogen dioxide gas concentration of 0.5 to 100 ppm. As shown in FIG. 10(A), the change in R value according to each concentration is correlated, and the concentration of 0.5 to 10 ppm of nitrogen dioxide gas and 10 to 100 Different sensitivities can be seen in ppm. 10(B) is a quantitative graph of this, and the quantitative expression for nitrogen dioxide of the sensor showed a quantitative curve of y = 0.1816x + 2.6512 at 0.5 to 10 ppm, and the correlation coefficient (r ² ) was very high as 0.9888. , shows a quantitative curve of y = 0.2087x + 12.3019 in the range of 10 to 100 ppm, and it can be seen that the correlation coefficient (r ² ) is 0.9915.

In addition, the response measurement time of the sensor to nitrogen dioxide decreased, and the time elapsed in the case of 0.5 ppm - 125 seconds, 10 ppm - 75 seconds, and 100 ppm - 110 seconds. Through this, it can be confirmed that the sensor of the present invention for nitrogen dioxide has very good reactivity and is an excellent sensor capable of real-time monitoring.

In addition, in order to confirm the gas selectivity of the sensor of the present invention, it was tested for various gases, and as a result of testing the reactivity to various gases, it showed excellent selectivity to nitrogen dioxide gas (FIG. 11). For example, the sensor response for various gas concentrations of 100 ppm is 32.9% nitrogen dioxide, 2% sulfuric acid, 3% hydrogen sulfide, 2.5% ammonia, 1.6% dimethyl sulfide, 1.5% acetaldehyde, 1.1%, 1.9% for 100% nitrogen and oxygen. % of the response. It has a sensitivity equivalent to 11.3 times that of hydrogen sulfide gas detection. The graphene sensor developed in the present invention indicates that the nitrogen dioxide gas quantification process is not disturbed by other gases or gases.

Therefore, it should be understood that the above-described embodiments are exemplary in all respects and are not intended to limit the present invention to the above-described embodiments, and the scope of the present invention is defined by the following claims rather than the above detailed description. All changes or modifications derived from the meaning and scope of the claims and equivalent concepts should be construed as being included in the scope of the present invention.

The present invention has very high sensitivity and selectivity to nitrogen dioxide gas, has a detection limit of 0.5 ppm or less, and can be widely used practically in hospitals, medical facilities, pharmaceutical manufacturing and related industries, and chemical handling industries.

In addition, the present invention has a very short reaction time to nitrogen dioxide gas and excellent correlation coefficient and quantitative curve, so it is very suitable for real-time nitrogen dioxide gas detection and quantification is possible.

10 Nitrogen dioxide gas detection sensor
11 board
12 graphene sheet
13 Zinc Oxide Nanosheet
14 Graphene sensor
20 chamber
30 Multimeter (detector)
40 Control and Recorder (PC)
50 Flow Control (MFC)
60 gas supply
100 Nitrogen Dioxide Gas Detection System

Claims (15)

Board;
a graphene sheet positioned on the substrate; and
a zinc oxide nanosheet doped on the graphene sheet; Including, a nitrogen dioxide gas detection sensor. According to claim 1,
The graphene sheet is made of a single layer, nitrogen dioxide gas detection sensor. According to claim 1,
The zinc oxide nanosheet (ZnO nanosheet) is made of a single layer, or two or more layers, the nitrogen dioxide gas detection sensor. According to claim 1,
The average size of a single particle of the zinc oxide nanosheet (ZnO nanosheet) is 50 to 90 nm, nitrogen dioxide gas detection sensor. According to claim 1,
When the single particles of the zinc oxide nanosheet (ZnO nanosheet) are aggregated, the average size is 300 to 500 nm, a nitrogen dioxide gas detection sensor. According to claim 1,
The doping is performed by spin-coating a zinc oxide nanosheet (ZnO nanosheet) on the graphene sheet 4 to 6 times, the nitrogen dioxide gas detection sensor. According to claim 1,
The nitrogen dioxide gas detection sensor detects nitrogen dioxide gas within 150 seconds, a nitrogen dioxide gas detection sensor. According to claim 1,
The nitrogen dioxide gas detection sensor detects nitrogen dioxide gas at 20 to 35 ℃, nitrogen dioxide gas detection sensor. According to claim 1,
The nitrogen dioxide gas detection sensor is capable of detecting nitrogen dioxide gas at 0.001 to 1,000 ppm, a nitrogen dioxide gas detection sensor. According to claim 1,
The nitrogen dioxide gas detection sensor,
electrodes connected to both ends of the graphene sheet; and
The nitrogen dioxide gas detection sensor further comprising; a power supply unit for driving the nitrogen dioxide gas detection sensor. Preparing a zinc oxide nanosheet (ZnO nanosheet); and
Doping the zinc oxide nanosheet (ZnO nanosheet) on the upper portion of the graphene sheet; Containing, a nitrogen dioxide gas detection sensor manufacturing method. 12. The method of claim 11,
The step of doping the zinc oxide nanosheet (ZnO nanosheet) on the upper portion of the graphene sheet,
The method of manufacturing a nitrogen dioxide gas detection sensor, which is performed by immersing the graphene sheet in a solution containing zinc oxide nanosheets, and spin-coating the mixed solution at a speed of 900 to 1100 rpm for 200 to 400 seconds. . 13. The method of claim 12,
The spin coating is performed 4 to 6 times, the nitrogen dioxide gas detection sensor manufacturing method. 12. The method of claim 11,
The concentration of the solution containing the zinc oxide nanosheet (ZnO nanosheet) is 20 μL to 140 μL, nitrogen dioxide gas detection sensor manufacturing method. The nitrogen dioxide gas detection sensor according to any one of claims 1 to 10;
chamber;
control and recording devices;
flow control device; and
A gas supply device; including, a nitrogen dioxide gas detection system.

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