KR20180069372A - ZnO nanowire gas sensor functionalized with Au, Pt and Pd nanoparticle using room temperature sensing properties and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a gas sensor capable of selectively sensing a specific gas. The gas sensor according to an embodiment of the present invention includes a zinc oxide nanowire on which a metal nano-particle is arranged on the surface thereof. The metal nano-particle is at least one of gold (Au), platinum (Pt), and palladium (Pd), and selectively acts on carbon dioxide gas, toluene gas, and benzene gas, respectively.

Description

[0001] The present invention relates to a gas sensor using temperature-sensitive properties of ZnO nanowires functionalized with Au, Pt, and Pd metal particles, and a method of manufacturing the same,

The present invention relates to a gas sensor using temperature-sensitive properties of ZnO nanowires functionalized with Au, Pt, and Pd metal particles, and a method of manufacturing the same.

In order to maintain an uncontaminated environment, the need for sensitive and reliable chemical sensors is growing, so that a variety of hazardous chemical species can be traced and discovered.

Semiconductor metal oxides (SMOs) have been recognized as one of the promising material species of chemical sensors because they have good heat resistance, reliable sensing, low processing cost and relatively simple drive mechanism. However, the semiconductor metal oxide has a problem that the selectivity of the sensor is low.

Recently, in order to maximize the sensing ability of the semiconductor metal oxide, various kinds of metal oxide semiconductors can be used as one-directional nanostructures such as nanofiber, nanorod, nanotube, ), Nanoribbon, etc. have become increasingly popular.

On the other hand, one of the reasons why the application of a chemiresistive sensor is important is to detect disease markers in human breath breathing, which contains a large number of volatile organic compounds (VOCs) And diagnose the disease.

Such non-surgical diagnosis based on chemiresistive sensors is advantageous over commonly used methods such as monolayer or endoscopy. Information necessary for the diagnosis of a specific disease can be obtained by detecting a specific volatile organic compound (VOCs) known as a biomarker having a strong correlation with a specific disease in breath breathing. Hydrogen sulfide, acetone, toluene, ammonia, and carbon monoxide are biomarkers for halitosis, diabetes, lung cancer, kidney disease, and asthma, respectively.

The following prior art document discloses a gas sensor for detecting hydrogen comprising a metal oxide.

U.S. Patent Registration No. 9212055

An object of the present invention is to provide a gas sensor including zinc oxide nanowires on which gold nanoparticles capable of selectively sensing carbon monoxide, which are biomarkers for asthma diagnosis, are disposed on the surface.

Another object of the present invention is to provide a gas sensor including zinc oxide nanowires on which platinum nanoparticles capable of selectively detecting toluene, which is a biomarker for lung cancer diagnosis, are disposed on the surface.

It is another object of the present invention to provide a gas sensor including zinc oxide nanowires on the surface of which palladium nanoparticles capable of selectively detecting benzene as a biomarker for the diagnosis of leukemia are disposed.

It is still another object of the present invention to provide a method of manufacturing a gas sensor in which at least one metal particle of gold (Au), platinum (Pt), and palladium (Pd) is disposed on the surface of zinc oxide nanowires.

A gas sensor according to an embodiment of the present invention includes zinc oxide nanowires having metal nanoparticles disposed on a surface thereof and the metal nanoparticles are at least one of gold (Au), platinum (Pt), and palladium (Pd) , There is selective sensing capability for certain gases.

In addition, a gas sensor according to an embodiment of the present invention may include zinc oxide nanowires with gold (Au) nanoparticles disposed on the surface, and may have selective sensing capability for carbon monoxide.

Further, the gas sensor according to the embodiment of the present invention may include zinc oxide nanowires in which gold (Au) nanoparticles are disposed on the surface, and can be used for asthma diagnosis.

Further, a gas sensor according to an embodiment of the present invention may include zinc oxide nanowires with platinum (Pt) nanoparticles disposed on the surface, and may have selective sensing capability for toluene.

Further, the gas sensor according to the embodiment of the present invention may include zinc oxide nanowires in which platinum (Pt) nanoparticles are disposed on the surface, and can be used for diagnosis of lung cancer.

Further, a gas sensor according to an embodiment of the present invention may include zinc oxide nanowires with palladium (Pd) nanoparticles disposed on the surface, and may have selective sensing capability for benzene.

Further, a gas sensor according to an embodiment of the present invention may include zinc oxide nanowires in which palladium (Pd) nanoparticles are disposed on the surface, and may be used for diagnosis of leukemia.

An electrode connected to the nanowire; And a substrate disposed on one surface of the electrode.

A method of manufacturing a gas sensor according to another embodiment of the present invention includes: depositing a gold (Au) thin film on a zinc oxide nanowire (step 1); And heat-treating the deposited gold thin film to form gold nanoparticles (step 2), and selectively detecting carbon monoxide.

The gold thin film of step 1 may be 3 nm to 20 nm thick.

The gold thin film of step 1 may further include at least partly a gold thin film which is not converted into metal nanoparticles by the heat treatment of step 2. [

A method of manufacturing a gas sensor according to another embodiment of the present invention includes depositing a platinum (Pt) thin film on a zinc oxide nanowire (step 1); And thermally treating the deposited platinum thin film to form nanoparticles (step 2), and selectively detecting carbon monoxide.

The platinum thin film of step 1 may be 1 nm to 20 nm thick.

The platinum thin film of step 1 may further include at least partially a platinum thin film which has not been converted into platinum nanoparticles by the heat treatment of step 2 above.

A method of manufacturing a gas sensor according to another embodiment of the present invention includes the steps of preparing a palladium precursor solution (step 1); Immersing a gas sensor comprising zinc oxide nanowires in the palladium precursor solution of step 1 and irradiating ultraviolet rays (step 2); And heat treating the gas sensor including the zinc oxide nanowire irradiated with the gamma ray in the step 2 to form palladium nanoparticles on the nanowire (step 3), and selectively detecting benzene.

The ultraviolet irradiation in step 2 may be performed for 1 second to 5 minutes.

The ultraviolet irradiation in step 2 may be irradiated at a dose of 0.11 mW / cm ² to 3.0 mW / cm ² .

The gas sensor according to the embodiment of the present invention can selectively respond to carbon monoxide, toluene, and benzene gas, and can be utilized as a biomarker capable of biopsy. In addition, it can be applied to various industrial fields by selectively sensing carbon monoxide, toluene, and benzene gas.

1 shows a gas sensor according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line AA 'of FIG. 1. FIG.
FIG. 3A is a graph showing sensor resistance with respect to carbon monoxide according to a voltage change applied to the sensor under a condition of carbon monoxide 10 ppm at room temperature in a gold-functionalized gas sensor according to an embodiment of the present invention.
FIG. 3B is a graph showing the carbon monoxide sensitivity according to the change in voltage applied to the sensor when carbon monoxide is 10 ppm at room temperature in a gas sensor functionalized with gold according to an embodiment of the present invention and a gas sensor according to a comparative example.
4 is a graph showing the resistance to ethanol, benzene, toluene and carbon monoxide by applying a 7V voltage to the sensor at ambient temperature in a gold functional gas sensor according to an embodiment of the present invention.
FIG. 5A is a graph showing the sensor resistance to toluene according to the change in voltage applied to the sensor when the gas sensor functionalized with platinum according to an embodiment of the present invention is in a condition of 50 ppm toluene at room temperature. FIG.
FIG. 5B is a graph showing the toluene sensitivity according to the change in voltage applied to the sensor when the gas sensor functionalized with platinum according to an embodiment of the present invention, at a room temperature and under a condition of 50 ppm toluene.
6A is a graph showing the sensor resistance with a change in toluene concentration when a voltage of 20 V is applied to the sensor at room temperature in a platinum-functional gas sensor according to an embodiment of the present invention.
FIG. 6B is a graph showing the sensitivity of a gas sensor functionalized with platinum according to an embodiment of the present invention, when a voltage of 20 V is applied to the sensor at room temperature, according to the change in toluene concentration. FIG.
7A is a graph showing the resistance to benzene, carbon monoxide, ethanol and toluene at a concentration of 50 ppm when a voltage of 20 V is applied to the sensor in a platinum-functional gas sensor according to an embodiment of the present invention.
7B is a graph showing sensitivity to benzene, carbon monoxide, ethanol and toluene at a concentration of 50 ppm when a voltage of 20 V is applied to the sensor in a platinum-functional gas sensor according to an embodiment of the present invention.
8A is a graph showing the sensor resistance with a change in toluene concentration when a voltage of 5 V is applied to the sensor at room temperature in a platinum-functional gas sensor according to an embodiment of the present invention.
FIG. 8B is a graph showing the sensitivity to changes in toluene concentration when a voltage of 5 V and 20 V is applied to the sensor at room temperature in a platinum-functional gas sensor according to an embodiment of the present invention.
9A is a graph showing resistance to benzene, carbon monoxide, and ethanol toluene at a concentration of 50 ppm when a voltage of 5 V is applied to the sensor at room temperature in a platinum-functional gas sensor according to an embodiment of the present invention.
9B is a graph showing sensitivity to benzene, carbon monoxide, ethanol and toluene at a concentration of 50 ppm when a voltage of 5 V is applied to the sensor at room temperature in a platinum-functional gas sensor according to an embodiment of the present invention.
10A is a graph showing the sensor resistance according to the voltage change applied to the sensor when the gas sensor functionalized with palladium according to the embodiment of the present invention is in the condition of benzene 50 ppm at room temperature.
FIG. 10B is a graph showing the sensitivity of the gas sensor functionalized with palladium according to the embodiment of the present invention, according to the change in voltage applied to the sensor when the benzene concentration is 50 ppm at room temperature. FIG.
11A is a graph showing the sensor resistance with a change in benzene concentration when a voltage of 20V is applied to the sensor at room temperature in a palladium-functional gas sensor according to an embodiment of the present invention.
FIG. 11B is a graph showing the sensitivity of a gas sensor functionalized with palladium according to an embodiment of the present invention, when a voltage of 20 V is applied to the sensor at room temperature, according to the change in benzene concentration. FIG.
12A is a graph depicting the sensor resistance at a 50 ppm concentration of benzene, carbon monoxide, ethanol, and toluene conditions when a voltage of 20V at room temperature is applied to the sensor in a palladium functionalized gas sensor according to an embodiment of the present invention.
12B is a graph showing sensitivity at a 50 ppm concentration of benzene, carbon monoxide, ethanol, and toluene conditions when a voltage of 20 V at room temperature is applied to the sensor in a palladium-functional gas sensor according to an embodiment of the present invention.
13 is a flow chart of a method for manufacturing zinc oxide nanowires formed by a vapor-liquid-solid (VLS) growth method according to the production example of the present invention.
14 is a scanning electron microscope photograph of a zinc oxide nanowire according to the production example of the present invention.
15 is a flowchart of a method of manufacturing a gas sensor functionalized with gold nanoparticles according to another embodiment of the present invention.
FIGS. 16A to 16F are photographs of a gold nanoparticle according to a change in thickness of a gold thin film of step 2 in a method of manufacturing a gas sensor functionalized with gold nanoparticles according to another embodiment of the present invention. FIG.
FIG. 16G is a graph showing the diameter of gold nanoparticles according to the thickness of the gold thin film of step 2 in the method of manufacturing a gas sensor functionalized with gold nanoparticles according to another embodiment of the present invention. FIG.
17A is a graph showing the sensor resistance to carbon monoxide according to the thickness change of the gold thin film in step 2 in the method of manufacturing a gold functionalized gas sensor according to another embodiment of the present invention.
FIG. 17B is a graph showing sensor resistance and sensitivity according to changes in carbon monoxide concentration in a gas sensor manufactured by a method of manufacturing a gas sensor that is not functionalized with metal nanoparticles according to a comparative example of the present invention.
FIG. 17C is a graph showing sensitivity to carbon monoxide according to a thickness change of the gold thin film in step 2 in a method of manufacturing a gold functionalized gas sensor according to another embodiment of the present invention. FIG.
18 is a flow chart of a method of manufacturing a gas sensor functionalized with platinum nanoparticles according to another embodiment of the present invention.
FIGS. 19A to 19F are photographs of a platinum nanoparticle according to a process condition change of a method of manufacturing a gas sensor functionalized with platinum nanoparticles according to another embodiment of the present invention, using a scanning electron microscope. FIG.
20 is a flow chart of a method of manufacturing a gas sensor functionalized with palladium nanoparticles according to another embodiment of the present invention.
FIGS. 21A to 21D are photographs of a Palladium nanoparticle according to another embodiment of the present invention, the Palladium nanoparticle being observed by a scanning electron microscope according to a process condition change of a method of manufacturing a gas sensor functionalized with Palladium nanoparticles.
FIG. 21E is a graph showing the change in the diameter of palladium nanoparticles according to UV irradiation time in step 2 of the method of manufacturing a gas sensor functionalized with palladium nanoparticles according to another embodiment of the present invention. FIG.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Further, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings may be exaggerated for clarity of description, and the elements denoted by the same reference numerals in the drawings are the same elements. In the drawings, like reference numerals are used throughout the drawings. In addition, "including" an element throughout the specification does not exclude other elements unless specifically stated to the contrary.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a gas sensor 100 according to an embodiment of the present invention, and FIG. 2 shows a cutaway view of FIG. 1 cut along AA '.

2, a gas sensor 100 according to an embodiment of the present invention includes zinc oxide nanowires 130 having metal nanoparticles 131 disposed on its surface, and the metal nanoparticles include gold (Au) , Platinum (Pt), and palladium (Pd), and has selective sensing capability for a specific gas.

1, a gas sensor 100 according to an embodiment of the present invention may further include an electrode 120 connected to the nanowire 130 and a substrate 110 disposed on one surface of the electrode 120 have.

The substrate 110 may support and insulate the electrodes 120 disposed on the substrate 110. The substrate 110 is not particularly limited and may be a silicon wafer, a quartz substrate 110, an oxide substrate 110, or the like.

An electrode 120 may be disposed on the substrate 110. The electrode 120 forms a passage through which a current supplied from the power supply unit 140 flows and may supply current to the nanowire 130 disposed on the electrode 120. In addition, the nanowires 130 may be formed and supported.

The material of the electrode 120 may be a conductive material generally used in the field of electronic devices, and is not particularly limited. For example, the electrode 120 may have a shape in which Au-Pt-Ti is sequentially stacked. The method of manufacturing the electrode 120 is also not particularly limited. For example, by a photolithography process and a subsequent etching process.

The substrate 110 may be a silicon wafer, a quartz substrate 110, an oxide substrate 110, or the like, but is not limited thereto.

Next, an insulating layer (not shown) may be formed on the substrate 110. The insulating layer may serve to support and insulate the electrode 120. The substrate 110 and the insulating layer support the electrodes 120 formed on the substrate 110 and serve to insulate the electrodes 120 from each other. The insulating layer may be silicon oxide, silicon dioxide, silicon nitride, a polymer, or the like. In addition, an insulating layer may not be separately formed by forming the electrode 120 on the substrate 110 having the insulating property using the substrate 110 having an insulating property.

Subsequently, the electrode 120 may be formed on the substrate 110. The electrode 120 may be formed by a method commonly used in the art. For example, by a photolithography process. The electrode 120 is not particularly limited, but Au-Pt-Ti may be sequentially stacked. At this time, the thickness of each layer can be adjusted as needed.

The power supply unit 140 may supply current to the electrode 120. The current supplied through the power supply unit 140 may flow through the electrode 120 and the nanowire 130. The concentration of the gas can be measured by measuring the resistance and the change occurring in accordance with the current flow. In the present invention, the shape and principle of the power supply unit 140 are not particularly limited.

A nanowire 130 may be disposed on the electrode 120 and the nanowire 130 may extend from the electrode 120. However, the shape and arrangement of the nanowires 130 are not particularly limited.

The zinc oxide nanowire 130 has a higher specific surface area than that of a thin film or lump shape. Therefore, the gas sensor 100 including the nanowires 130 has high sensitivity to the gas to be measured, that is, sensitivity to the gas.

The principle that the gas sensor 100 including the nanowire 130 containing the metal oxide detects gas in the air is as follows.

When oxygen molecules in the air are adsorbed on the surface of the nanowire 130, electrons on the surface of the nanowire 130 may be trapped by the oxygen molecule to form an electron depletion layer on the surface of the nanowire 130.

If the oxidizing gas molecules are adsorbed on the surface of the nanowire 130, electrons on the surface of the nanowire 130 are further captured by the oxidizing gas molecules, so that the electron depletion layer can be further expanded. In this case, the electrical resistance of the nanowire 130 may increase due to an electron depletion layer formed on the surface of the nanowire 130.

If the reducing gas molecules are adsorbed on the surfaces of the nanowires 130, different results may be obtained when the oxidizing gas molecules are adsorbed on the surface of the nanowires 130. When the reducing gas molecules are adsorbed on the surfaces of the nanowires 130, the oxygen molecules and the reducing gas molecules may react with each other and separate from the surface of the nanowires 130. Accordingly, the electron depletion layer formed on the surface of the nanowire 130 may be reduced to reduce the electrical resistance of the nanowire 130.

As described above, when the gas molecules are desorbed and adhered to the surface of the nanowire 130, electron exchange may occur. In order to effectively perform such an electron exchange, a thermal energy of more than a predetermined value is required. In general, the gas concentration measurement can be performed at a temperature of 200 ° C to 400 ° C.

Also, since the gas sensor 100 according to the embodiment of the present invention includes the metal nanoparticles 131 disposed on the surface of the nanowire 130, the sensitivity to gas is higher.

The method of forming the metal nanoparticles on the nanowire is not limited, but generally, a method of forming metal nanoparticles by forming a thin film and then performing heat treatment may be used. For example, a metal thin film may be deposited on a nanowire by sputtering or atomic layer deposition equipment, and then heat treatment may be performed. Alternatively, a solution in which metal nanoparticles are dispersed may be sprayed onto the nanowire, It may be formed by immersing it in a dispersed solution and then performing heat treatment.

In one embodiment, a gas sensor according to an embodiment of the present invention may comprise zinc oxide nanowires with gold (Au) nanoparticles disposed on the surface, and preferably have selective sensing capability for carbon monoxide.

The gas sensor according to an embodiment of the present invention may include zinc oxide nanowires in which gold (Au) nanoparticles are disposed on the surface, and is preferably used for asthma diagnosis.

Carbon monoxide is a bio-marker used to diagnose asthma. If carbon monoxide contains more than a certain amount of exhalation, or if the variation of the contained amount is above a certain limit, the association with the disease may be suspected. Therefore, the gas sensor 100 according to the embodiment of the present invention can be used for asthma diagnosis.

Hereinafter, in the present invention, the gas sensor including the zinc oxide nanowire in which the gold nanoparticles are disposed on the surface may be referred to as a "gas sensor functionalized with gold ".

FIG. 3A is a graph showing the relationship between the resistance of the sensor and the change of the voltage applied to the sensor at 1 V, 3 V, 5 V, 7 V, and 10 V under a condition of carbon monoxide 10 ppm at room temperature in a gold functional gas sensor according to an embodiment of the present invention FIG. 3B is a graph showing the relationship between the voltage applied to the sensor and the voltage applied to the sensor when the carbon monoxide gas is 10 ppm at room temperature in the gas sensor functionalized with gold according to the embodiment of the present invention and the gas sensor not functioning with gold according to the comparative example of the present invention. (R _a / R _g ) according to the change of the carbon monoxide concentration. In the sensitivity (Ra / Rg), Ra is a value obtained by measuring a resistance on air after a constant voltage is applied to the gas sensor, and Rg is a value obtained by measuring resistance after charging the gas to be measured.

As a result of the measurement, the gold (R _a / R _g ) became 1.17, 1.625, 2.315, 2.872, and 2.47 as the voltage applied to the gas sensor changed to 1 V, 3 V, 5 V, 7 V, And it was confirmed that the sensitivity was highest when a voltage of 7 V was applied to the gas sensor.

FIG. 4 is a graph showing the resistance against ethanol, benzene, toluene and carbon monoxide when a voltage of 7 V is applied to a sensor at room temperature and a carbon monoxide concentration is 10 ppm in a gold-functionalized gas sensor according to an embodiment of the present invention. As shown in FIG. 4, the gas sensor functionalized with gold is not sensitive to other reducing gases such as ethanol, benzene and toluene under the same measurement conditions, so that the gas sensor functionalized with gold exhibits selectivity to carbon monoxide .

As a result, it can be seen that sensitivity to carbon monoxide is enhanced by functioning as gold nanoparticles on the surface of zinc oxide nanowires.

As an example, a gas sensor according to an embodiment of the present invention may include zinc oxide nanowires with platinum (Pt) nanoparticles disposed on the surface, and may have selective sensing capability for toluene.

The gas sensor according to an embodiment of the present invention may include zinc oxide nanowires on which platinum (Pt) nanoparticles are disposed on the surface, and is preferably used for diagnosis of lung cancer.

Toluene is a bio-marker used to diagnose lung cancer. If toluene contains more than a certain amount of exhalation, or if the variation of the contained amount is above a certain limit, the relationship with the disease may be suspected. Thus, the gas sensor 100 according to an embodiment of the present invention can be used for lung cancer diagnosis.

Hereinafter, in the present invention, the gas sensor including the zinc oxide nanowire in which the platinum nanoparticles are disposed on the surface may be referred to as a "gas sensor functionalized with platinum ".

5A is a graph showing the resistance of a gas sensor while applying a voltage of 1, 5, 10 and 20 V to a gas sensor while injecting 50 ppm of toluene at room temperature in a platinum-functional gas sensor according to an embodiment of the present invention And FIG. 5B shows the sensitivity by deriving the sensitivity under the same measurement conditions as described above.

As a result of the above measurement results, the sensitivity values were 1.046, 1.49, 2.485, and 2.864, respectively. As the applied voltage was increased, the sensitivity was increased.

6A is a graph showing the relationship between the concentration of toluene and the concentration of toluene in a gas sensor functionalized with platinum while applying a voltage of 20 V at room temperature to a gas sensor functionalized with platinum, 1, 10 and 50 ppm. FIG. 6B is a graph showing the sensitivity of the sensor under the same measurement conditions as described above.

As a result of the measurement, when the concentration of toluene was 0.1 ppm, the gas sensor functionalized with platinum was not sensitive, and the sensitivities of gas sensors functionalized with platinum at the concentrations of 1, 10 and 50 ppm were 1.234, 1.84 and 2.864 As a result, it was confirmed that the sensitivity increased as the concentration of toluene increased.

Referring to the above experiment, when the voltage of 20 V is applied to the gas sensor functionalized with platinum, the highest sensitivity is obtained under the condition that the concentration of toluene is 50 ppm. FIG. 7A is a graph showing the sensitivity of the gas sensor functionalized with platinum according to the embodiment of the present invention Carbon monoxide, ethanol, and toluene at a concentration of 50 ppm when a voltage of 20 V is applied to the sensor at room temperature, and FIG. 7B is a graph showing the sensitivity derived from the same measurement conditions as above.

From the above results, it can be seen that the gas sensor functionalized with platinum reacts with ethanol, benzene and carbon monoxide, but the sensitivity is significantly different from that of toluene. From the above results, it can be confirmed that the gas sensor functionalized with platinum has selectivity for benzene even at room temperature.

8A is a graph showing the sensor resistance when 0.1, 1, 10 and 50 ppm of toluene is injected when a voltage of 5 V is applied to the sensor at room temperature in a platinum-functional gas sensor according to an embodiment of the present invention, FIG. 8B shows the same measurement conditions as above and sensitivity at 20V.

In the case of 0.1 ppm, similarly, the gas sensor functionalized with platinum was not sensitive to toluene gas, but the sensitivity increased to 1.075, 1.158 and 1.49 as the concentrations increased to 1, 10 and 50 ppm, respectively. However, compared to when a voltage of 20 V was applied to the gas sensor functionalized with platinum, the sensitivity was very low and the unstable response behavior to toluene gas was confirmed.

9A is a graph showing resistance to benzene, carbon monoxide, ethanol and toluene at a concentration of 50 ppm when a voltage of 5 V is applied to the sensor at room temperature in a platinum-functional gas sensor according to an embodiment of the present invention, and FIG. 9B Shows the sensitivity by deriving the sensitivity under the same conditions as described above.

As a result of the measurement, in the gas sensor functionalized with platinum according to the embodiment of the present invention, when a voltage of 5 V was applied to the gas sensor at room temperature, a sensitivity of 1.49 was obtained for toluene of 50 ppm. However, as shown in FIGS. 9A and 9B, the resistance measurement and the sensitivity of 50 ppm of carbon monoxide, benzene, and ethanol gas were derived, and as a result, the sensitivity was significantly lower than that of toluene gas. As a result, it can be confirmed that the sensor has a selective response characteristic to toluene gas when a low voltage is applied to a gas sensor functionalized with platinum.

In conclusion, the functionalization of zinc oxide nanowires as platinum nanoparticles increases sensitivity to toluene.

As an example, a gas sensor according to an embodiment of the present invention may include zinc oxide nanowires with palladium (Pd) nanoparticles disposed on the surface, and may have selective sensing capability for benzene.

The gas sensor according to an embodiment of the present invention may include zinc oxide nanowires on which palladium (Pd) nanoparticles are disposed on the surface, and is preferably used for diagnosis of leukemia.

Benzene is a bio-marker used to diagnose leukemia. If benzene contains more than a certain amount of exhalation, or if the variation of the contained amount is above a certain limit, the relevance of the disease may be suspected. Accordingly, the gas sensor 100 according to an embodiment of the present invention can be used for the diagnosis of leukemia.

Hereinafter, in the present invention, a gas sensor including zinc oxide nanowires in which the palladium nanoparticles are disposed on the surface may be referred to as a "gas sensor functionalized with palladium ".

10A is a graph showing the sensor resistance when a voltage is applied to the sensor at 1, 5, 10 and 20 V when the gas sensor is functionalized with palladium according to an embodiment of the present invention and the benzene is 50 ppm at room temperature, Shows the sensitivity derived from the same measurement conditions as described above.

As a result of the measurement, it was confirmed that the sensitivity was highest for benzene when a voltage of 20V was applied in order of 1.062, 1.162, 1.538 and 2.202, respectively.

Referring to FIG. 11A, in a gas sensor functionalized with palladium according to an embodiment of the present invention, when a voltage of 20 V is applied to a gas sensor functionalized with platinum in the previous experiment, FIG. 11B is a graph showing the sensitivity of the sensor when the benzene concentration is changed to 0.1, 1, 10 and 50 ppm when the sensor is applied to the sensor, and FIG.

As a result of the measurement, when the benzene concentration was 0.1 ppm, the palladium-functionalized gas sensor according to the embodiment of the present invention was not sensitive and the sensitivity of 1.181, 1.232 and 2.202 was obtained at benzene concentrations of 1, 10 and 50 ppm, The higher the concentration, the better the sensitivity of the gas sensor.

Referring to FIG. 12A, when a voltage of 20 V is applied to a gas sensor functionalized with palladium in the previous experiment, the highest sensitivity is obtained under the condition that the concentration of benzene is 50 ppm. Referring to FIG. 12A, 12B is a graph showing the sensor resistance at a concentration of 50 ppm of benzene, carbon monoxide, ethanol, and toluene when a voltage of 20 V is applied to the sensor at room temperature in order to make the standard of the gas sensitivity of benzene the highest. And the sensitivities derived from the same measurement conditions as those described above.

As a result of the measurement, it was confirmed that the gas sensor functionalized with palladium according to the embodiment of the present invention exhibits about two times the sensitivity to benzene in the same measurement conditions, compared to the sensitivity to toluene, carbon monoxide and ethanol. Based on the above results, it can be seen that the gas sensor functionalized with palladium has selectivity for benzene.

As a result, it can be seen that sensitivity to benzene is enhanced by functionalizing the surface of zinc oxide nanowires with palladium nanoparticles.

A method of manufacturing a gas sensor for selectively sensing carbon monoxide according to another embodiment of the present invention includes depositing a gold (Au) thin film on a zinc oxide nanowire (step 1); And heat-treating the deposited gold thin film to form gold nanoparticles (Step 2).

Hereinafter, a method of manufacturing a gas sensor for selectively sensing carbon monoxide according to another embodiment of the present invention will be described in detail for each manufacturing step.

A step 1 of a method of manufacturing a gas sensor for selectively sensing carbon monoxide according to another embodiment of the present invention is a step of depositing a gold thin film on a gas sensor including a prepared zinc oxide nanowire, On the zinc oxide nanowire. For example, the gold thin film may be deposited through a sputtering apparatus or an atomic layer deposition apparatus.

The thickness of the gold thin film is preferably 3 nm to 20 nm.

If the thickness of the gold thin film is less than 3 nm, the gold thin film may not be deformed into gold nanoparticles at a subsequent stage, and gold nanoparticles may not be formed. As a result, the performance of a gas sensor functionalized with gold may not be sufficient. If the thickness of the gold thin film is more than 20 nm, the thickness of the untransformed thin film becomes thick after the gold thin film is converted into the gold nanoparticles, and the sensitivity of the gas sensor may be lowered or the sensor may not be sensitive to the target gas.

The heat treatment in step 2 may be performed preferably in a temperature range of 450 ° C to 550 ° C.

The gold thin film of step 1 may further include at least partly a gold thin film which is not converted into metal nanoparticles by the heat treatment of step 2. [

FIGS. 16B to 16F are photographs of a gold thin film deposited on a zinc oxide nanowire and a gold nanoparticle formed by a subsequent heat treatment by a scanning electron microscope. FIG. In FIG. 16B, after a gold thin film was deposited to a thickness of 3 nm, the temperature was raised to 500 ° C per minute at 10 ° C, followed by heat treatment for about 30 minutes. It can be seen that fine nanoparticles are formed on the surface of the nanowire as compared with the nanowires on which the gold thin film is not deposited.

Referring to FIGS. 16B to 16F, it can be seen that as the thickness of the deposited gold thin film increases, the size of the gold nanoparticles changes. Thus, it can be seen that by controlling the thickness of the gold thin film, the average diameter of the subsequently produced gold nanoparticles and the surface structure of the zinc oxide nanowires can be changed.

FIG. 16G shows the relationship between the gold thin film deposited through the measurement and the subsequently formed gold nanoparticles.

A method of manufacturing a gas sensor for selectively sensing toluene according to another embodiment of the present invention includes depositing a platinum (Pt) thin film on a zinc oxide nanowire (step 1); And heat treating the deposited platinum thin film to form nanoparticles (step 2).

Hereinafter, a method of manufacturing a gas sensor for selectively sensing toluene according to another embodiment of the present invention will be described in detail for each manufacturing step.

Step 1 of the method of manufacturing a gas sensor for selectively sensing toluene according to another embodiment of the present invention is a step of depositing a platinum thin film on the prepared zinc oxide nanowire and depositing a platinum thin film surrounding the zinc oxide nanowire on the zinc oxide nanowire As shown in FIG. For example, the platinum thin film may be deposited through a sputtering apparatus or an atomic layer deposition apparatus, and a thin film may be formed through a process similar to the formation of the foregoing platinum thin film.

The thickness of the platinum thin film is preferably 1 nm to 20 nm.

If the thickness of the platinum thin film is less than 1 nm, the platinum thin film may not be deformed into the platinum nanoparticles at a subsequent stage, and there is a possibility that the platinum nanoparticles may not be formed. As a result, the performance of the gas sensor functionalized with platinum may not be sufficient. If the thickness of the platinum thin film is more than 20 nm, the platinum thin film may be converted into platinum nanoparticles, and then the thickness of the unconverted thin film may become thick to lower the sensitivity of the gas sensor, or the sensor may not be sensitive to the target gas.

Step 2 of the method of manufacturing a gas sensor for selectively sensing toluene according to another embodiment of the present invention is a step of growing the metal nanoparticles by heat treatment of the deposited platinum thin film and converting the platinum thin film into platinum nanoparticles.

The heat treatment in step 2 may be performed at a temperature of 600 ° C to 650 ° C.

The platinum thin film of step 1 may further include at least partially a platinum thin film which has not been converted into platinum nanoparticles by the heat treatment of step 2. [

19A to 19F are photographs of a platinum thin film deposited on a zinc oxide nanowire and a platinum nanoparticle formed by a subsequent heat treatment by a scanning electron microscope. 19A to 19C, it can be seen that the average diameter of the platinum nanoparticles changes due to the change in the heat treatment temperature which is subsequently performed by the gas sensor including the zinc oxide nanowire having the same 5 nm platinum thin film deposited thereon. Also, referring to FIGS. 19D to 19F, it can be seen that the average diameter of the platinum nanoparticles changes due to the change of the subsequent heat treatment temperature in the gas sensor including the zinc oxide nanowire having the same 10 nm platinum thin film deposited thereon.

From the above results, it was confirmed that when the temperature of the heat treatment was 500 ° C (temperature increase rate of 10 ° C / min, holding the normal temperature for 30 minutes), the platinum thin film deposited did not change into platinum nanoparticles by the subsequent heat treatment. When the temperature of the heat treatment was raised at 650 ° C. (temperature raising rate 10 ° C./minute and maintained at a normal temperature for 30 minutes) at 600 ° C. (temperature raising rate of 10 ° C./minute and holding the normal temperature for 30 minutes), the diameter of the average platinum nano- And the results thereof are shown in Fig. 19g.

A method of manufacturing a gas sensor for selectively sensing benzene according to another embodiment of the present invention includes the steps of: preparing a palladium precursor solution (step 1); Immersing a gas sensor comprising zinc oxide nanowires in the palladium precursor solution of step 1 and irradiating ultraviolet rays (step 2); And forming a palladium nanoparticle on the nanowire by heat treating the gas sensor including the zinc oxide nanowire irradiated with ultraviolet rays in the step 2 (step 3).

Hereinafter, a method of manufacturing a gas sensor for selectively sensing benzene according to another embodiment of the present invention will be described in detail for each manufacturing step.

Step 1 of the method of manufacturing a gas sensor for selectively sensing benzene according to another embodiment of the present invention is a step of preparing a solution of a palladium precursor.

Step 2 of the method of manufacturing a gas sensor for selectively sensing benzene according to another embodiment of the present invention is a step of immersing a gas sensor including zinc oxide nanowires in the palladium precursor solution of Step 1 and irradiating ultraviolet rays thereto .

The method of forming nanoparticles by ultraviolet irradiation can perform the reduction process without adding a reducing agent to the aqueous solution, uniformly irradiate the ultraviolet rays to a wide range, and can generate homogeneously the reduction reaction in the solution.

The ultraviolet irradiation in step 2 may be conducted for 1 second to 5 minutes.

When the ultraviolet irradiation is performed for less than 1 second, fine metal particles can be formed, but the area ratio of metal nanoparticles and zinc oxide nanowires, which are large variables of gas sensitivity, is relatively reduced. There is a problem in that coarse metal particles are formed and connection of metal particles occurs on the surface of the metal oxide nanowire.

The ultraviolet irradiation in step 2 may be irradiated at a power of 0.05 nW / cm ² to 0.20 nW / cm ² .

If the intensity of the ultraviolet ray irradiation exceeds 0.20 nW / cm ² , the amount of photo-reduced neutral metal atoms increases, and the growth rate of metal particles formed thereby increases, making it difficult to form metal nanoparticles of appropriate size Can be. If the intensity of the ultraviolet ray irradiation is less than 0.05 nW / cm ² , metal nanoparticles may not be formed.

Step 3 of the method for manufacturing a gas sensor for selectively sensing benzene according to another embodiment of the present invention includes heating the gas sensor including the zinc oxide nanowires irradiated with ultraviolet rays in the step 2 to heat the palladium nanoparticles to the nanowire .

FIGS. 21a to 21d show a method of manufacturing a gas sensor that selectively senses the following benzene according to another embodiment of the present invention, wherein the palladium nanoparticles formed by the subsequent heat treatment are photographed with a scanning electron microscope And Fig. 21E shows this as the palladium nanoparticle diameter for the UV irradiation time.

As a result of the measurement, the diameter of the palladium nanoparticles was about 25 nm when the UV irradiation time was 5 seconds, and about 17 nm, 16 nm and 20 nm were measured at 1 second, 10 seconds and 20 seconds, respectively.

Comparative Example 1 - Zinc oxide Nanowire  growth

Step i - As shown in FIG. 13, a 50 nm thick titanium (Ti) layer as an adhesion layer, 200 nm of platinum (Pt) as an electrode layer and a 200 nm thick gold (Au) layer as a catalyst layer were formed on a (2 mm x 2 mm) PIE fabricated by a photolithography process. ) Were sequentially deposited on the substrate by using a sputtering apparatus (Infovion, IS-210 Model).

The deposition conditions were as follows: an inert gas Ar was flown in a high vacuum of 10 ^-5 Torr to generate a plasma, and a power of 100 W was applied to Ti deposition, 30 W for Au deposition and 30 W for Pt deposition, , And 18 nm of Pt were deposited.

Step ii - Add about 20 ml of acetone to the beaker, insert the thin film deposited electrode forming wafer in step i, and apply titanium, gold, platinum thin film deposited on the wafer at 40 kHz frequency with an ultrasonic device (HWASHIN, POWER SONIC 405) The PR pattern was lifted off. After that, it was washed with deionized water (DI water) and dried using a nitrogen gas (N ₂ gas, 99.99%). This forms the desired electrode shape.

Step iii - Powder obtained by mixing 0.1 g of zinc powder and 0.1 g of graphite was immersed in an alumina boat, and the electrode-formed wafer was immobilized on the alumina boat according to the above step ii. Then, a Vapor-Liquid-Solid , VLS) growth apparatus (Muffle Tube Type Furnace (2Zone)), and placed at a distance of 2 cm from each other. The temperature was raised to 950 ° C at a rate of 10 ° C / min and maintained for 1 hour. The wafer and the alumina boat were charged into the apparatus and argon and oxygen gas were flowed at about 400 and 25 sccm per minute.

As shown in Fig. 1 by step i, step ii and step iii, zinc oxide nanowires are grown on the electrode of step i, and have a diameter of about 100 to 150 nm , A gas sensor comprising zinc oxide nanowires in elongated fiber form was prepared.

Example 1 - Fabrication of gold functionalized gas sensor

Step 1 - Preparation of a gas sensor formed with zinc oxide nanowires

Zinc oxide nanowire according to Comparative Example 1 was prepared.

Step 2 - Gold thin film sputtering

For the deposition of the gold thin film, argon (Ar) which is an inert gas is flowed in a high vacuum atmosphere of 5 * 10 ^-5 Torr by using a sputtering apparatus (Infovion, IS-210 Model) to accelerate the ionized argon, (3) x 0.5t (99.99%) of gold (Au target φ3 "x 0.5t 99.99%) to deposit a gold atom on the substrate. Zinc nanowire.

Step 3 - Conversion to gold nanoparticles through gold thin-film heat treatment

The gas sensor on which the gold thin film deposited by the above step 2 was deposited was heat-treated at 500 ° C, a temperature raising rate of 10 ° C / min, and a holding time of 0.5 hours by using an electric furnace (Hantech, Electric Box Furnace, Model C- And the gold nanoparticles were formed on the surface of the zinc oxide nanowire to prepare a gas sensor for detecting carbon monoxide.

Example 2 - Fabrication of gold functionalized gas sensor

A gas sensor functionalized with gold was prepared in the same manner as in Example 1, except that the gold thin film was deposited to about 5 nm in the step 2 of Example 1 above.

Example 3 - Fabrication of a gas sensor functionalized with gold

A gas sensor functionalized with gold was prepared in the same manner as in Example 1 except that a gold thin film was deposited at about 10 nm in the step 2 of Example 1 above.

Example 4 - Fabrication of gold functionalized gas sensor

A gas sensor functionalized with gold was prepared in the same manner as in Example 1 except that a gold thin film was deposited at about 20 nm in the step 2 of Example 1 above.

Example 5 - Fabrication of gold functionalized gas sensor

A gas sensor functionalized with gold was prepared in the same manner as in Example 1, except that a gold thin film was deposited at about 30 nm in the step 2 of Example 1 above.

Example 6 - Fabrication of gas sensor functionalized with platinum

Step 1 - Preparation of a gas sensor formed with zinc oxide nanowires

Zinc oxide nanowire according to Comparative Example 1 was prepared.

Step 2 - Platinum thin film sputtering

Platinum thin film deposition was performed by flowing argon (Ar), which is an inert gas, in a high vacuum of 5 * 10 ^-5 Torr using a sputtering apparatus (Infovion, IS-210 Model) to accelerate the ionized argon, (Pt target φ 3 "x 0.5t 99.99%), and the gold atoms were ejected and deposited on the substrate. As a principle, the deposition was carried out at a rate of 18 nm per minute by applying 30 W of electric power. Zinc nanowire.

Step 3 - Conversion to platinum nanoparticles through gold thin film heat treatment

The gas sensor on which the platinum thin film prepared in the above step 2 was deposited was heat-treated using an electric furnace (Hantech Electric Box Furnace, Model C-A14P) at a temperature of 600 캜, a temperature raising rate of 10 캜 / And a platinum nanoparticle formed on the surface of the zinc oxide nanowire was manufactured.

Example 7 - Fabrication of gas sensor functionalized with platinum

A gas sensor functionalized with platinum was prepared in the same manner as in Example 6 except that a platinum thin film was deposited to a thickness of about 10 nm in the step 2 of Example 6 above.

Example 8 - Fabrication of a gas sensor functionalized with palladium

Step 1 - Preparation of a gas sensor formed with zinc oxide nanowires

Zinc oxide nanowire according to Comparative Example 1 was prepared.

Step 2 - Precursor solution preparation and ultraviolet irradiation

0.017 g of palladium chloride (PdCl ₂ ) as a precursor solution, 8.5 g of 2-propanol and 8.5 g of acetone were mixed and stirred in a stirrer (Korea Science and Engineering, MP-8) for 24 hours to obtain a precursor solution Prepared. As shown in Fig. 21, the stirred solution was put in a beaker, and the zinc oxide nanowire gas sensor prepared in Comparative Example 1 was placed, and the beaker was charged into a UV apparatus (ORC uv-M03A). Thereafter, ultraviolet light was irradiated for 1 second at an intensity of 0.11 mW / cm ² . The ultraviolet ray irradiation was performed at room temperature, the lamp used was a halogen lamp, and the main wavelength was 360 nm. After the ultraviolet ray irradiation was completed, natural drying was performed in a waiting state.

Step 3 - Convert to palladium nanoparticles by heat treatment

The gas sensor to which UV was irradiated in the step 2 was heated at 600 ° C by a vapor-liquid-solid (VZS) growth apparatus (Muffle Tube Type Furnace (2Zone) Min, and a holding time of 0.5 hours. As a result, it was confirmed that palladium nanoparticles having a diameter of about 25 nm were formed.

Example 9 - Manufacture of gas sensor functionalized with palladium

A gas sensor functionalized with palladium was prepared in the same manner as in Example 8, except that the UV irradiation time was 5 seconds in the step 2 of Example 8.

Example 10 - Manufacture of gas sensor functionalized with palladium

A gas sensor functionalized with palladium was prepared in the same manner as in Example 8 except that the UV irradiation time was changed to 10 seconds in the step 2 of Example 8.

Example 11 - Preparation of gas sensor functionalized with palladium

A gas sensor functionalized with palladium was prepared in the same manner as in Example 8, except that the UV irradiation time was 20 seconds in the step 2 of Example 8.

Experimental Example 1 - Metal nanoparticles according to gold deposition conditions diameter  observe

A gas sensor including zinc oxide nanowires deposited with thicknesses of 3 nm, 5 nm, 10 nm, 20 nm, and 30 nm was prepared through Examples 1 to 5.

The prepared gas sensor was heat-treated under the same conditions, and gold nanoparticles and zinc oxide nanowires formed according to each condition were photographed using a scanning electron microscope (HR-SEM, HITACHI, SU 8010) To f. As shown in FIGS. 16A to 16F, the smooth surface of the zinc oxide nanowire was observed in FIG. 16A, and in FIG. 16B, gold nanoparticles having an average diameter of 20.49 nm were observed on the surface of the zinc oxide nanowire I could. Through the same observation, the diameters of the gold nanoparticles were increased to 35.24, 111.68, 122.25 and 159.8 nm, respectively, by scanning electron microscopy and measurement of FIGS. 16c to 16f. As a result, it was confirmed that the diameters of the gold nanoparticles formed by the subsequent process increase with the increase in the thickness of the generally deposited gold film although not in a perfect linear relationship.

Experimental Example 2 - Gas Sensor Performance Comparison

The gas sensor for detecting carbon monoxide prepared according to Examples 1 to 3 was prepared and the gas resistance against the concentration of carbon monoxide of 10 ppm was measured twice while applying a voltage of 7 V to the gas sensor at room temperature. The gas sensor for detecting carbon monoxide prepared by Examples 4 and 5 was not sensitive to carbon monoxide. As shown in Fig. 17C, as the thickness of the gold thin film deposited in step 2 of the gas sensor manufacturing method increased to 3 nm, 5 nm and 10 nm, the sensitivity of the gas sensor for detecting carbon monoxide prepared by the subsequent step was 1.593, 2.371 It was confirmed that it increased to 2.872. 17B, the sensitivity of the gas sensor in which the gold nanoparticles were not formed on the zinc oxide surface was measured to be 1.051, and the sensitivity of the gas sensor for detecting carbon monoxide according to the embodiment of the present invention Was about 2.7 times higher than that of the control group.

As a result, the gold nanoparticles are placed on the surface of the zinc oxide nanowire, indicating that the sensitivity to carbon monoxide is increased.

Experimental Example 3 - Metal nanoparticles according to platinum deposition conditions diameter  observe

Example 6 and Example 7 were used to prepare a gas sensor including a zinc oxide nanowire having a platinum thin film deposited to a thickness of 5 nm and a thickness of 10 nm.

The prepared gas sensor was subjected to heat treatment under the conditions of 500, 600 and 650 ° C, and platinum nanoparticles and zinc oxide nanowires formed according to each condition were subjected to high-resolution scanning electron microscope equipment (HR-SEM, HITACHI company, SU 8010) , Which is shown in Figs. 19 (a) to 19 (f). As shown in Figs. 19A and 19D, it was confirmed that the platinum thin film was not converted into platinum nanoparticles under the heat treatment condition of 500 < 0 > C. Compared with Experimental Example 1, the melting point (1768 ° C) of platinum is much higher than the melting point of gold (1064 ° C), and it is expected that the platinum thin film is not converted into platinum nanoparticles under the heat treatment condition of relatively low temperature of 500 ° C can do. As shown in Figs. 19B and 19E, a plurality of platinum nanoparticles formed on the surface of zinc oxide could be observed under the heat treatment conditions of 600 DEG C, and as shown in Figs. 19C and 19F, the heat treatment temperature rose to 650 DEG C , Platinum nanoparticles with larger diameters were observed compared with the heat treatment conditions at 600 ° C.

The above observation results are shown in Fig. 19g, and the average diameter results are shown in Table 1.

Experimental Example 4 - Palladium nanoparticles diameter  Measure

In order to observe the change of the diameter of the palladium nanoparticles according to the UV irradiation time in the step 2 of the method for producing a gas sensor for detecting benzene according to another embodiment of the present invention, And observed through a scanning electron microscope. The results are shown in FIGS. 21A to 21D, and the measurement results of the palladium nanoparticle diameter are shown in FIG. 21E.

As a result of the above observation, when the UV irradiation time was 5 seconds, the diameter of the palladium nanoparticles was found to be the largest at about 25 nm, and the irradiation time was measured at diameters of 17, 16 and 20 nm at 1, 10 and 20 seconds respectively It was confirmed that the UV irradiation time and the diameter of the palladium nanoparticles were not clearly related.

The present invention is not limited to the above-described embodiment and the accompanying drawings, but is intended to be limited by the appended claims. Therefore, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. I will say.

100: Gas sensor
110: substrate
120: Electrode
130: nanowire
131: metal nanoparticles
140:
131: metal nanoparticles

Claims (17)

Wherein the metal nanoparticles comprise at least one of gold (Au), platinum (Pt), and palladium (Pd), wherein the metal nanoparticles comprise zinc oxide nanowires with the metal nanoparticles disposed on the surface, Features a gas sensor.
The method according to claim 1,
Wherein the metal nanoparticles are gold (Au) and have selective sensing capability for carbon monoxide.
The method according to claim 1,
Wherein the metal nanoparticles are gold (Au) and are used for asthma diagnosis.
The method according to claim 1,
Wherein the metal nanoparticles are platinum (Pt) and have selective sensing capability for toluene.
The method according to claim 1,
The metal nanoparticles are platinum (Pt), and are used for diagnosis of lung cancer.
The method according to claim 1,
Wherein the metal nanoparticles are palladium (Pd) and have selective sensing capability for benzene.
The method according to claim 1,
Wherein the metal nanoparticles are palladium (Pd), and are used for diagnosis of leukemia.
The method according to claim 1,
An electrode connected to the nanowire; And
And a substrate disposed on one surface of the electrode.
Depositing a gold (Au) thin film on the zinc oxide nanowire (step 1); And
And forming gold nanoparticles by heat-treating the deposited gold thin film (Step 2).
10. The method of claim 9,
Wherein the gold thin film of step 1 has a thickness of 3 nm to 20 nm.
10. The method of claim 9,
Wherein the gold thin film of step 1 further comprises at least partly a gold thin film which has not been converted into metal nanoparticles by the heat treatment of step 2 above.
Depositing a platinum (Pt) thin film on the zinc oxide nanowire (step 1); And
(2) heat-treating the deposited platinum thin film to form nanoparticles (2).
13. The method of claim 12,
Wherein the platinum thin film of step 1 has a thickness of 1 nm to 20 nm.
13. The method of claim 12,
Wherein the platinum thin film of step 1 further comprises at least partially a platinum thin film which has not been converted into platinum nanoparticles by the heat treatment of step 2. 2. The method of claim 1,
Preparing a palladium precursor solution (step 1);
Immersing a gas sensor comprising zinc oxide nanowires in the palladium precursor solution of step 1 and irradiating ultraviolet rays (step 2); And
And a step (3) of forming palladium nanoparticles on the nanowires by heat treating the gas sensor including the zinc oxide nanowires irradiated with gamma rays in the step 2 (step 3). .
16. The method of claim 15,
Wherein the step 2 is irradiated with ultraviolet light for 1 second to 5 minutes.
16. The method of claim 15,
Wherein the ultraviolet irradiation of step 2 is irradiated at a dose of 0.11 mW / cm ² to 3.0 mW / cm ² .

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