KR20240068355A - Gas sensor and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a sensitive layer; and a catalyst layer applied on the sensitive layer, wherein the catalyst layer includes a metal oxide to which palladium and vanadium is added or a zeolite to which palladium and vanadium are added. Disclosed is a gas sensor and a method of manufacturing the same.

Description

Gas sensor and method for manufacturing the same}

The present invention relates to an oxide semiconductor type gas sensor and a method of manufacturing the same, and more specifically, to a gas sensor capable of detecting ethylene, which affects flowering, growth, maturation, etc. of plants, with high selectivity and sensitivity.

Oxide semiconductor type gas sensors have various advantages such as small integration, economical, high sensitivity, fast response, and the ability to detect gas concentration as an electric signal using a simple circuit, such as detecting explosive gases and automobile exhaust gases. , It is widely used in various application fields such as driver's breathability measurement and industrial gas detection.

Recently, as the industry has become more advanced and interest in human health and environmental pollution has deepened, there is a demand for gas sensors that can be used for more precise detection of indoor and outdoor environmental gases, gas sensors for self-diagnosis of diseases, and high-performance artificial olfactory gas sensors that can be mounted on mobile devices. As is rapidly increasing, the demand for oxide semiconductor type gas sensors that exhibit high sensitivity and high selectivity for detection gases at minute concentrations is also increasing significantly.

Ethylene (C ₂ H ₄ ) is one of the representative plant hormone gases and is known as a substance that regulates many life activities such as ripening of fruits, flowering of flowers, germination of seeds, and growth of cells even at low concentrations. Therefore, it is very important to detect ethylene gas with high sensitivity and selectivity.

However, ethylene is known to be a gas that is very difficult to selectively detect with existing oxide semiconductor gas sensors due to its simple structure and low reactivity.

The purpose of the present invention is to provide a gas sensor that detects ethylene, a plant hormone gas, with high selectivity and high sensitivity, and a method of manufacturing the gas sensor.

In addition, the present invention aims to detect ethylene gas with high sensitivity and selectivity, which was difficult to detect with high selectivity and sensitivity with conventional methods due to its low reactivity and simple structure, using a double-layer gas sensor structure with an adjusted catalyst layer.

Meanwhile, the technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly apparent to those skilled in the art from the description below. It will be understandable.

A gas sensor according to an embodiment of the present invention includes a sensitive layer; and a catalyst layer applied on the sensitive layer, wherein the catalyst layer may include a metal oxide to which palladium and a transition element are added, or a zeolite to which palladium and a transition element are added.

Additionally, the sensitive layer may contain a metal oxide semiconductor as its main component.

Additionally, the metal oxide may include any one of Ti, Al, and Si.

Additionally, the catalyst layer can reform ethylene into a gas more reactive than ethylene.

Additionally, in the catalyst layer, palladium may be included in an amount of 2 wt% to 20 wt% relative to the metal of the metal oxide.

Additionally, in the catalyst layer, the transition element may be included in an amount of 4 wt% to 20 wt% relative to the metal of the metal oxide.

Additionally, the transition element may include at least one of the group including vanadium, silver, chromium, manganese, cobalt, nickel, and copper.

Meanwhile, a method of manufacturing a gas sensor according to an embodiment of the present invention includes the steps of (A) disposing a sensitive layer; and (B) disposing a catalyst layer on the sensitive layer; It includes, and the catalyst layer may include a metal oxide to which palladium and a transition element are added, or a zeolite to which palladium and a transition element are added.

Additionally, the sensitive layer may contain a metal oxide semiconductor as its main component.

Additionally, the metal oxide may include any one of Ti, A, and B.

Additionally, the catalyst layer can reform ethylene into a gas more reactive than ethylene.

Additionally, in the catalyst layer, palladium may be included in an amount of 2 wt% to 20 wt% relative to the metal of the metal oxide.

Additionally, in the catalyst layer, the transition element may be included in an amount of 4 wt% to 20 wt% relative to the metal of the metal oxide.

Additionally, the transition element may include at least one of the group including vanadium, silver, chromium, manganese, cobalt, nickel, and copper.

According to embodiments of the present invention, it is possible to sensitize ethylene with high selectivity and high sensitivity.

Meanwhile, the effects that can be obtained from the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below. You will be able to.

1 is a flowchart showing a method of manufacturing a gas sensor according to an embodiment of the present invention,
Figure 2 is a cross-sectional view showing a gas sensor manufactured according to a method for manufacturing a gas sensor according to an embodiment of the present invention;
Figure 3 is an image showing the structure of gas-sensitive particles in a gas sensor according to an embodiment of the present invention;
Figure 4 is an image showing the structure and composition of catalyst layer particles in a gas sensor according to an embodiment of the present invention;
Figure 5 is an image showing that, in the gas sensor according to an embodiment of the present invention, the gas sensitive layer (made of the particles of Figure 3) and the catalyst layer (made of the particles of Figure 4) form a double layer;
Figure 6 shows the gas sensors according to Examples 1-1, 1-2 and 1-3 at an operating temperature of 300°C to 400°C for ethylene, ethanol, TMA, ammonia, hydrogen sulfide, carbon monoxide and hydrogen. This is a graph comparing gas sensitivity,
7 shows ethylene, ethanol, TMA, ammonia, and hydrogen sulfide in the gas sensors according to Comparative Examples 1-1, 1-2, 1-3, and 1-4 at an operating temperature of 300 ° C. to 400 ° C. , This is a graph comparing gas sensitivity to carbon monoxide and hydrogen,
Figure 8 is a graph showing the gas dynamic response characteristics (A) and the lower detection limit of gas by concentration of the gas sensor in the gas sensor according to an embodiment of the present invention (B). As a result of fitting based on when the gas sensitivity is above 0.2, the lower limit of ethylene detection of this sensor is 7.3 ppb. 8C and D are graphs showing the short-term and long-term stability of the developed sensor, and it can be seen that the sensor operates stably over a long period of time.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the attached drawings. Embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited to the following embodiments. This example is provided to more completely explain the present invention to those skilled in the art. Therefore, the shapes of elements in the drawings are exaggerated to emphasize clearer explanation.

The configuration of the invention to clarify the solution to the problem to be solved by the present invention will be described in detail with reference to the accompanying drawings based on preferred embodiments of the present invention, and the reference numbers to the components in the drawings will be the same. Components are given the same reference numbers even if they are in different drawings, and it is stated in advance that components of other drawings can be cited when necessary when explaining the relevant drawings.

In the present invention, ripening of fruits, flowering of flowers, and growth of cells are achieved by applying a catalyst layer of titanium oxide (TiO ₂ ) containing palladium (Pd) nanoparticles and vanadium oxide (V ₂ O ₅ ) on the oxide-based gas sensitive layer. , ethylene, a plant hormone gas that can control plant growth and seed germination, can be decomposed into highly reactive gases or interfering gases into less reactive gases, allowing target gases to be detected with high sensitivity. This allows highly selective gas detection by reducing the sensitivity of interfering gases to a negligible level.

FIG. 1 is a flowchart showing a method of manufacturing a gas sensor according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a gas sensor manufactured according to a method of manufacturing a gas sensor according to an embodiment of the present invention.

However, the structure of the gas sensor according to the present invention is not limited to that presented here, and any structure of a gas sensor having a sensitive layer made by physically mixing a gas sensitive structure and a catalyst structure is applicable to the present invention.

Referring to FIGS. 1 and 2 together, the method for manufacturing a gas sensor according to an embodiment of the present invention includes the steps of preparing gas-sensitive particles and catalyst particles (S10), forming a sensitive layer (S20), and forming a catalyst layer (S30). may include.

First, prepare gas-sensitive particles and catalyst particles (S10).

The gas-sensitive particles may have a metal oxide semiconductor as a main ingredient, and may include at least one of various sensitive materials selected from the group consisting of In ₂ O ₃ , SnO ₂ , ZnO, Fe ₂ O ₃ , WO ₃ , Co ₃ O ₄ , Cr ₂ O ₃ and CuO. may include.

Hereinafter, the gas-sensitive particles will be described based on an example made of In ₂ O ₃ , but the gas-sensitive particles in the present invention are not limited to In ₂ O ₃ .

First, prepare a spray solution by mixing indium precursor and sucrose and stirring. Indium precursors include Indium nitrate, Indium chloride, and Indium sulfate.

Next, the single-day process ultrasonic spray pyrolysis is performed. This process may include generating fine droplets by spraying a spray solution and introducing the fine droplets into the reactor to synthesize and recover the powder.

The size of the fine droplets can be controlled by the pressure inside the spray device, the concentration of the spray solution, the viscosity of the spray solution, and the intensity of ultrasonic waves. The temperature inside the reactor is maintained around 600°C. At least one carrier gas selected from oxygen, air, Ar, N ₂ , and He may be used to introduce fine droplets into the reactor. The residence time of the fine droplets in the reactor can be adjusted by changing the flow rate of the carrier gas. Although the residence time is short in this high-temperature reactor, by heating, the organic or polymer precursors contained in the fine droplets are decomposed and the components of the desired composition are obtained. Only one remains.

Catalyst particles can be prepared from metal oxide (Pd-V ₂ O ₅ -TiO ₂ ) to which palladium and vanadium are added or zeolite to which palladium and vanadium are added.

Meanwhile, in a specific example of the present invention, the description is based on an example in which the metal oxide is composed of titanium, but the metal oxide in the catalyst particle is not limited to TiO ₂ in the present invention.

Thereafter, in the sensitive layer forming step (S20), the sensitive layer 100 is applied on the substrate 400, such as alumina, silicon, or silica, on which the two electrodes 300 are located, using gas sensitive particles.

Here, application is used to include various methods such as printing, brushing, blade coating, dispensing, and micropipette dropping. Next, the solvent and organic components are removed through heat treatment to form the sensitive layer 100.

Thereafter, in the catalyst layer forming step (S30), the catalyst layer 200 is disposed by applying it on the sensitive layer 100. Here, the application method refers to various thin film formation methods such as electron beam evaporation, sputtering or dispensing, drop application, and spin application, and the catalyst layer 200 can be applied on top of the response layer 100. If it is a known method, it is not necessarily limited thereto.

Next, if necessary to remove organic contaminants and stabilize the incomplete phase, heating, that is, heat treatment, may be performed. For example, heat treatment may be performed at a temperature of about 100°C to 600°C.

Meanwhile, the sensitive layer 100 is made of a material that is sensitive to various gases. In one example, it may be made of hollow spheres.

The catalyst layer 200 is formed on the upper surface of the sensitive layer 100. Meanwhile, the catalyst layer 200 is separated from the sensitive layer 100 and is formed on the upper surface of the sensitive layer 100. For example, the catalyst layer 200 may exist only on the top surface of the sensitive layer 100.

As described above, the catalyst layer 200 may be constructed based on catalyst particles. The catalyst layer 200 may be composed of catalyst particles (metal oxide (Pd-V ₂ O ₅ -TiO ₂ ) to which palladium and vanadium are added or zeolite to which palladium and vanadium are added).

Here, the catalyst layer 200 oxidizes relatively highly reactive ethanol, TMA, hydrogen sulfide, ammonia, carbon monoxide, and hydrogen into non-reactive or low reactive CO ₂ and H ₂ O, thereby lowering the sensitivity in the response layer 100. On the other hand, in the case of ethylene, which has very high stability and low reactivity, it is decomposed into gases more reactive than ethylene by the catalyst layer 200, so that high sensitivity of ethylene can be achieved.

Here, 'reactivity' can be defined as 'reactivity with the adsorbed oxygen of an oxide semiconductor type gas sensor', and in the case of an oxide semiconductor type gas sensor, gas sensitivity appears due to the reaction between oxygen adsorbed on the surface and the target gas. do. At this time, in the case of a low reactivity gas, there is little reaction with oxygen adsorbed on the surface, resulting in low sensitivity, while in the case of highly reactive gas, there is a large reaction with oxygen adsorbed on the surface, resulting in high sensitivity.

Meanwhile, the reaction in which ethylene is decomposed into highly reactive gases by the catalyst layer 200 can reform ethylene into acetaldehyde using a catalyst containing Pd.

Here, ethylene is decomposed into acetaldehyde through the oxidation and reduction reactions of Pd, and at this time, it is the transition element that assists the oxidation and reduction reactions of Pd. That is, in the present invention, specific examples of V among transition elements are described, but it is not limited to this, and of course, various transition elements can be used.

Specifically, the transition element may include at least one of the group including vanadium, silver, chromium, manganese, cobalt, nickel, and copper.

That is, by providing the catalyst layer 200 on the upper surface of the sensitive layer 100, ethylene with low reactivity passes through the catalyst layer 200 separated from the sensitive layer 100 before reaching the area adjacent to the electrode of the sensitive layer 100. Passing through first, ethylene is reformed or decomposed into highly reactive gases by the catalyst layer 200 and reaches the area adjacent to the electrode 300 of the sensitive layer 100, and the reformed or decomposed highly reactive gases reach the electrode ( By being oxidized in the area adjacent to 300), it can have high selectivity and high sensitivity to the test gas.

On the other hand, the interfering gas is converted to an unreactive or low-reactivity gas or completely oxidized by the catalyst layer 200, thereby lowering the sensitivity.

Meanwhile, in the catalyst particles, palladium may be included in an amount of 2 wt% to 20 wt% based on the metal of the metal oxide.

Here, if palladium is less than 2wt% compared to the metal of the metal oxide, there may be a problem of greater sensitivity to other gases compared to ethylene because the reforming reaction of ethylene does not occur much, and if palladium is more than 20wt% compared to the metal of the metal oxide, ethylene There may be a problem where the sensitivity of ethylene decreases again due to a complete oxidation reaction. In both cases, highly sensitive and highly selective detection of ethylene compared to the interfering gas is difficult.

Meanwhile, in the catalyst particles, vanadium may be included in an amount of 4 wt% to 20 wt% based on the metal of the metal oxide.

Here, if vanadium is less than 4wt% compared to the metal in the metal oxide, there may be a problem of greater sensitivity to other gases compared to ethylene because the reforming reaction of ethylene does not occur much, and if vanadium is more than 20wt% compared to the metal in the metal oxide, Ti There may be a problem of interfering with the reforming reaction of ethylene by limiting the effect of the carrier containing.

Meanwhile, the catalyst layer 200 disposed on the sensitive layer 100 preferably has a thickness of 0.1 ㎛ to 100 ㎛.

Here, if the thickness of the catalyst layer 200 is less than 0.1㎛, there may be a problem of not producing the effect of reforming ethylene, and if the thickness of the catalyst layer 200 is more than 100㎛, ethylene is completely oxidized to reduce gas sensitivity. There may be problems reducing it again.

The electrode 300 is connected to the upper surface of the substrate 400. The sensitive layer 100 is coated on the substrate 400 while the electrode 300 is connected to the upper surface of the substrate 400.

Accordingly, the electrode 300 is provided between the substrate 400 and the sensitive layer 100. A resistance measuring device that measures electrical resistance is connected to the electrode 300 connected to the substrate 400 and the sensitive layer 100. When the sensitive layer 100 comes into contact with the test gas, the electrical resistance of the sensitive layer 100 changes, and the test gas can be detected by measuring the changed electrical resistance of the sensitive layer 100 using a resistance measuring device. The electrode 300 may be made of a conductive material such as platinum (Pt).

The electrode 300 and the sensitive layer 100 are provided on the substrate 400 to be electrically connected to each other. The substrate 400 is provided as an insulator. For example, the substrate 400 may be provided as a substrate made of an insulating material such as an alumina (Al ₂ O ₃ ) substrate or a silica (SiO ₂ )/silicon (Si) substrate, or as a MEMS-based substrate.

The heater 500 heats the sensitive layer 100 to a temperature at which the sensitive layer 100 activates detection of the gas to be tested. According to one embodiment, the heater 500 may be provided on the bottom of the substrate 400. The heater 500 may include a heating wire that generates heat through electrical resistance. According to one embodiment, the heater 500 may heat the sensitive layer 100 to the operating temperature.

Hereinafter, detailed examples and comparative examples of manufacturing a gas sensor using the above-described gas sensor manufacturing method will be compared, and the characteristics of the gas sensor manufactured according to each example will be described.

[Example 1-1]

First, 0.05 mol of indium nitrate and 0.0.5 mol of sucrose were mixed in 500 mL of distilled water and stirred for 1 hour. The synthesized precursor was sprayed at a flow rate of 10 L min-1 (in O ₂ ) and passed through an electric furnace (700 ℃) connected to the spray outlet, where it was immediately heat treated to form an indium oxide (In ₂ O ₃ ) hollow structure. .

Next, the TiO ₂ egg yolk structure containing Pd and V ₂ O ₅ used as a catalyst layer was synthesized by spray drying.

Dissolve 0.00037 mol of ammonium vanadate(V), 0.01 mol of titanium(IV) isopropoxide, and 0.037 mol of dextrin in 1.2% nitric acid solution to prepare a total of 500 mL of spray solution ([V]:[TiO ₂ ] = 4: 100). Afterwards, 2 wt% of palladium(II) nitrate ([Pd]:[TiO ₂ ]=2:100) was added and stirred for 1 hour.

The synthesized solution is spray dried at inlet and outlet temperatures of 250°C and 120°C. Afterwards, the Pd-V ₂ O ₅ -TiO ₂ precursor was subjected to post-heat treatment at 500°C for 3 hours to prepare a catalyst layer with a V ₂ O ₅ -TiO ₂ egg yolk structure to which 2 wt% Pd- was added.

The hollow structure fine powder obtained in this way was mixed with an organic binder and screen-printed to a thickness of about 10 ㎛ on an alumina substrate on which a gold electrode was formed, dried at 200 ° C. for 2 hours, and then an In ₂ O ₃ gas sensitive layer was prepared. Afterwards, V ₂ O ₅ -TiO ₂ egg yolk structure to which 2 wt % of Pd was added was applied through screen printing, and V ₂ O ₅ -TiO ₂ to which 2 wt % of Pd was added was applied by heat treatment at 500°C for 2 hours. An In ₂ O ₃ gas sensor was manufactured.

Next, the manufactured gas sensor was placed in a quartz tube and the change in resistance was measured while alternately injecting pure air or air+mixed gas. The gas was mixed in advance and then the concentration was rapidly changed using a 4-way valve.

[Example 1-2]

First, an In ₂ O ₃ sensitive layer was manufactured through the same process as Example 1-1. Afterwards, V ₂ O ₅ -TiO ₂ to which 4 wt % of Pd was added was applied through screen printing, and then heat treated at 500°C for 2 hours to obtain V ₂ O ₅ -TiO ₂ to which 4 wt % of Pd was added. _{A 2} O ₃ gas sensor was manufactured. Other gas sensor evaluation processes are the same as Example 1-1.

[Example 1-3]

First, an In ₂ O ₃ sensitive layer was manufactured through the same process as Example 1-1. Afterwards, V ₂ O ₅ -TiO ₂ nanoparticles to which 2 wt % of Pd was added were applied through screen printing, and V ₂ O ₅ -TiO ₂ to which 2 wt % of Pd was added were applied by heat treatment at 500°C for 2 hours. An In ₂ O ₃ gas sensor was manufactured. Other gas sensor evaluation processes are the same as Example 1-1.

[Comparative Example 1-1]

First, an In ₂ O ₃ hollow structure was manufactured through the same process as Example 1-1. The hollow structure fine powder obtained in this way was mixed with an organic binder, screen printed to a thickness of 10 ㎛ on an alumina substrate on which a gold electrode was formed, and heat treated at 500 ° C. for 2 hours to prepare an In ₂ O ₃ gas sensitive layer. Other gas sensor evaluation processes are the same as Example 1-1.

[Comparative Example 1-2]

First, an In ₂ O ₃ sensitive layer was manufactured through the same process as Example 1-1. Afterwards, V ₂ O ₅ -TiO ₂ to which 1 wt% of Pd was added was applied through screen printing, and V ₂ O ₅ -TiO ₂ to which 1 wt% of Pd was added was applied by heat treatment at 500°C for 2 hours. _{A 2} O ₃ gas sensor was manufactured. Other gas sensor evaluation processes are the same as Example 1-1.

[Comparative Example 1-3]

First, an In ₂ O ₃ sensitive layer was manufactured through the same process as Example 1-1. Then, V ₂ O ₅ -TiO ₂ was produced through the same process as in Example 1-1 except for the addition of palladium(II) nitrate, and it was applied on the In ₂ O ₃ response layer. Finally, an In ₂ O ₃ gas sensor coated with V ₂ O ₅ -TiO ₂ was manufactured by heat treatment at 500°C for 2 hours. Other gas sensor evaluation processes are the same as Example 1-1.

[Comparative Example 1-4]

First, an In ₂ O ₃ sensitive layer was manufactured through the same process as Example 1-1. Then, TiO ₂ to which 2 wt% of Pd was added was produced through the same process as in Example 1-1, except for the addition of ammonium vanadate (V), and this was applied on the In ₂ O ₃ response layer. . Finally, an In ₂ O ₃ gas sensor coated with TiO ₂ to which 2 wt% Pd was added was manufactured by heat treatment at 500°C for 2 hours. Other gas sensor evaluation processes are the same as Example 1-1.

Meanwhile, the above-mentioned examples and comparative examples are summarized in [Table 1] below.

Sensitive layer Pd content ratio in catalyst layer (wt%) V in the catalyst layer
Content ratio (wt%) Structure of catalyst particles Example 1-1 In ₂ O ₃ 2 4 Egg yolk structure Example 1-2 In ₂ O ₃ 4 4 Egg yolk structure Example 1-3 In ₂ O ₃ 2 4 nanoparticles Comparative Example 1-1 In ₂ O ₃ - - hollow structure Comparative Example 1-2 In ₂ O ₃ One 4 Egg yolk structure Comparative Example 1-3 In ₂ O ₃ 0 4 Egg yolk structure Comparative Example 1-4 In ₂ O ₃ 4 0 Egg yolk structure

[Characteristics Evaluation]

Figure 3 is an image showing the structure of gas-sensitive particles in a gas sensor according to an embodiment of the present invention;

FIG. 3 is an image showing the structure of gas-sensitive particles in a gas sensor according to an embodiment of the present invention, FIG. 4 is an image showing the structure and composition of catalyst layer particles in a gas sensor according to an embodiment of the present invention, and FIG. 5 is an image showing that, in the gas sensor according to an embodiment of the present invention, the gas sensitive layer (made of the particles of FIG. 3) and the catalyst layer (made of the particles of FIG. 4) form a double layer.

Figure 6 shows the gas sensors according to Examples 1-1, 1-2 and 1-3 at an operating temperature of 300°C to 400°C for ethylene, ethanol, TMA, ammonia, hydrogen sulfide, carbon monoxide and hydrogen. This is a graph comparing gas sensitivity.

Referring to FIG. 6, it can be seen that in Examples 1-1 and 1-2, high sensitivity and high selectivity for ethylene are secured compared to other interfering gases (ethanol, TMA, ammonia, hydrogen sulfide, carbon monoxide, hydrogen) at all operating temperatures. there is. In Example 1-3, it can be confirmed that high sensitivity and selectivity for ethylene is secured compared to other interfering gases at a temperature of 350 ° C. or higher. This shows that when the previously mentioned composition is used in the catalyst layer, high sensitivity to ethylene, regardless of the structure, is achieved. It can be confirmed that a gas-sensitive material showing high selectivity can be developed.

In Example 1-3, the egg yolk structure (Examples 1-1 and 1-2) can promote the reforming reaction of ethylene gas due to its structural ease compared to nanoparticles. Therefore, when using a catalyst layer with an egg yolk structure, a gas sensor with even better ethylene gas sensitivity characteristics can be developed. On the other hand, when using nanoparticles (Example 1-3), it can be confirmed that the gas sensitivity characteristics are insufficient compared to the egg yolk-structured sensing material. However, in this case as well, the characteristics are at a usable level, regardless of the structure of the sensing material. If a catalyst layer having the above composition is created, highly sensitive and highly selective detection of ethylene may be possible.

7 shows ethylene, ethanol, TMA, ammonia, and hydrogen sulfide in the gas sensors according to Comparative Examples 1-1, 1-2, 1-3, and 1-4 at an operating temperature of 300 ° C. to 400 ° C. , This is a graph comparing gas sensitivity to carbon monoxide and hydrogen.

Referring to FIG. 7, in Comparative Examples 1-1 to 1-4, it can be seen that the sensitivities of other interfering gases are similar or greater than the sensitivities of ethylene at all operating temperatures. This means that a highly sensitive gas-sensitive material with high selectivity for ethylene cannot be secured with other compositions, including the comparative example.

Figure 8 is a graph showing the gas dynamic response characteristics (A) and the lower detection limit of gas by concentration of the gas sensor in the gas sensor according to an embodiment of the present invention (B). As a result of fitting based on when the gas sensitivity is above 0.2, the lower limit of ethylene detection of this sensor is 7.3 ppb. 8C and D are graphs showing the short-term and long-term stability of the developed sensor, and it can be seen that the sensor operates stably over a long period of time.

The above detailed description is illustrative of the present invention. Additionally, the foregoing is intended to illustrate preferred embodiments of the present invention, and the present invention can be used in various other combinations, modifications, and environments. That is, changes or modifications are possible within the scope of the inventive concept disclosed in this specification, the scope equivalent to the written disclosure, and/or the technology or knowledge in the art. The written examples illustrate the best state for implementing the technical idea of the present invention, and various changes required for specific application fields and uses of the present invention are also possible. Accordingly, the detailed description of the invention above is not intended to limit the invention to the disclosed embodiments. Additionally, the appended claims should be construed to include other embodiments as well.

Claims (14)

Sensitive layer; and
It includes a catalyst layer applied on the sensitive layer,
The catalyst layer is a gas sensor comprising a metal oxide to which palladium and a transition element are added or a zeolite to which palladium and a transition element are added.
According to paragraph 1,
The sensitive layer is
A gas sensor whose main ingredient is a metal oxide semiconductor.
According to paragraph 1,
The metal oxide is
A gas sensor containing any one of Ti, Al, and Si.
According to paragraph 1,
The catalyst layer is a gas sensor that reformes ethylene into a gas more reactive than ethylene.
According to paragraph 1,
In the catalyst layer,
A gas sensor in which the palladium is contained in an amount of 2 wt% to 20 wt% compared to the metal of the metal oxide.
According to paragraph 1,
In the catalyst layer,
A gas sensor in which the transition element is contained in an amount of 4 wt% to 20 wt% relative to the metal of the metal oxide.
According to paragraph 1,
A gas sensor wherein the transition element includes at least one of the group including vanadium, silver, chromium, manganese, cobalt, nickel, and copper.
(A) disposing a sensitive layer; and
(B) disposing a catalyst layer on the sensitive layer; Including,
The catalyst layer is a method of manufacturing a gas sensor comprising a metal oxide to which palladium and a transition element are added or a zeolite to which palladium and a transition element are added.
According to clause 8,
The sensitive layer is
Method for manufacturing a gas sensor containing metal oxide semiconductor as the main ingredient.
According to clause 8,
The metal oxide is
Method for manufacturing a gas sensor containing any one of Ti, Al, and Si.
According to clause 8,
The catalyst layer is a method of manufacturing a gas sensor in which ethylene is reformed into a gas more reactive than ethylene.
In clause 7,
In the catalyst layer,
A method of manufacturing a gas sensor wherein the palladium is contained in an amount of 2 wt% to 20 wt% compared to the metal of the metal oxide.
In clause 7,
In the catalyst layer,
A method of manufacturing a gas sensor wherein the transition element is contained in an amount of 4wt% to 20wt% relative to the metal of the metal oxide.
In clause 7,
A method of manufacturing a gas sensor wherein the transition element includes at least one of the group including vanadium, silver, chromium, manganese, cobalt, nickel, and copper.