KR102627784B1 - Hydrogen gas sensor and Method for manufacturing thereof - Google Patents

Abstract

The present invention relates to a hydrogen gas sensor, and more specifically, to a hydrogen gas sensor capable of operating at room temperature and having high sensitivity and selectivity to hydrogen gas, and a method of manufacturing the same.
The hydrogen gas sensor according to the present invention includes a metal oxide layer; A first electrode and a second electrode positioned spaced apart from each other on the metal oxide layer; a metal nanoparticle layer located in an area where the first electrode and the second electrode are spaced apart; A polymer layer located on the metal nanoparticle layer; and a porous color conversion sensing layer located on the polymer layer and containing metal oxide, metal nanoparticles, and silicate.

Description

Hydrogen gas sensor and method for manufacturing same {Hydrogen gas sensor and Method for manufacturing thereof}

The present invention relates to a hydrogen gas sensor, and more specifically, to a hydrogen gas sensor with high sensitivity and selectivity to hydrogen gas and a method of manufacturing the same.

Hydrogen energy, which is emerging due to the depletion of fossil fuels and environmental pollution problems, has the potential to be used in almost all fields used in the current energy system, including basic industrial materials, general fuels, hydrogen cars, hydrogen airplanes, fuel cells, and nuclear fusion energy. I have it.

However, hydrogen gas has a wide explosive concentration range (4-75%) and small ignition energy, so it is easily ignited by even the slightest static electricity, so even a small amount of hydrogen gas leaked can be very dangerous. Accordingly, high-performance sensors that can quickly and accurately detect hydrogen gas are required to reduce major accidents and casualties caused by hydrogen leaks.

To date, sensors using catalytic combustion or heat wire, SiO2, AlN metal oxide (nitride) semiconductors, and sensors using Schottky barrier diodes with a two-pole structure using bulk Pd, Pt, SiC, GaN, etc. Although various hydrogen gas sensors are being developed, they are not only large in size and complex in structure, but also expensive. In addition, since it operates at a high temperature of over 300 ℃, it not only consumes a lot of power, but also has limitations such as low sensitivity to hydrogen.

Accordingly, as disclosed in Republic of Korea Patent Publication No. 10-0870126, 'Method for manufacturing hydrogen gas sensor using Pd nanowire', research on hydrogen gas sensor materials and structures that can optimize performance as a hydrogen gas sensor is in progress. However, there is still a need to develop a sensor that operates with high sensitivity to hydrogen gas at room temperature.

: Republic of Korea Patent Publication No. 10-0870126

The purpose of the present invention is to provide a hydrogen gas sensor that can operate at room temperature and has high sensitivity and selectivity for hydrogen gas.

Another object of the present invention is to provide a method of manufacturing a hydrogen gas sensor capable of sensing hydrogen gas with high sensitivity.

The hydrogen gas sensor according to the present invention includes a metal oxide layer; A first electrode and a second electrode positioned spaced apart from each other on the metal oxide layer; a metal nanoparticle layer located in an area where the first electrode and the second electrode are spaced apart; A polymer layer located on the metal nanoparticle layer; and a porous color conversion sensing layer located on the polymer layer and containing metal oxide, metal nanoparticles, and silicate.

In the hydrogen gas sensor according to an embodiment of the present invention, the metal of the metal oxide of the porous color conversion sensing layer is a group consisting of zinc (Zn), titanium (Ti), molybdenum (Mo), and tungsten (W). It may be any one or more selected from.

In the hydrogen gas sensor according to an embodiment of the present invention, the metal of the metal nanoparticles of the porous color conversion sensing layer may be palladium.

In the hydrogen gas sensor according to an embodiment of the present invention, the silicate may be manufactured by a condensation reaction of a C _1-4 alkoxysilane-based compound.

In the hydrogen gas sensor according to an embodiment of the present invention, the weight ratio of the metal oxide: the metal nanoparticle: the silicate included in the porous color conversion sensing layer may be 1:0.5 to 1.5:0.1 to 0.5.

In the hydrogen gas sensor according to an embodiment of the present invention, the surface of the metal oxide layer in the area where the first electrode and the second electrode are spaced apart includes a first area where the metal nanoparticle layer is located, and a surface where the metal nanoparticle layer is located. It may include a second region that is not used.

In the hydrogen gas sensor according to an embodiment of the present invention, the area of the second region may be 50% to 90% of the total area of the surface of the metal oxide layer partitioned by the first electrode and the second electrode. .

In the hydrogen gas sensor according to an embodiment of the present invention, the polymer of the polymer layer may be an acrylate-based polymer.

In the hydrogen gas sensor according to an embodiment of the present invention, the polymer of the polymer layer may be non-porous polymethyl methacrylate.

In the hydrogen gas sensor according to an embodiment of the present invention, the metal oxide layer may be located on a flexible substrate.

In the hydrogen gas sensor according to an embodiment of the present invention, the metal oxide layer may be located on the shrink film.

The method of manufacturing a hydrogen gas sensor according to the present invention includes the steps of a) forming a metal oxide layer on one surface of the insulating layer; b) forming a first electrode and a second electrode spaced apart from each other on one surface of the metal oxide layer that is not in contact with the insulating layer; c) forming a metal nanoparticle layer with a thickness of 1 to 5 nm in the area where the first electrode and the second electrode are spaced apart; d) forming a polymer layer on the metal nanoparticle layer; e) preparing a coating solution by mixing a first solution containing metal oxide and metal nanoparticles and a second solution containing a C _1-4 alkoxysilane compound; and f) forming a porous color conversion sensing layer by applying and drying the coating solution on the polymer layer.

In the method for manufacturing a hydrogen gas sensor according to an embodiment of the present invention, in step f), the C _1-4 alkoxysilane-based compound may be converted to a silicate through a condensation reaction.

In the method of manufacturing a hydrogen gas sensor according to an embodiment of the present invention, in step c), the metal nanoparticle layer may be formed by depositing on a partial area of the surface of the metal oxide layer.

In the hydrogen gas sensor according to an embodiment of the present invention, step d) may include applying and drying polymethyl methacrylate dissolved in a solvent on the metal nanoparticle layer.

In the hydrogen gas sensor according to an embodiment of the present invention, in step d1), the solvent may be a halogenated alkoxy benzene compound.

The hydrogen gas sensor according to the present invention has a structure in which a metal oxide layer, a metal nanoparticle layer, a polymer layer, and a porous color conversion sensing layer are laminated in that order, enabling room temperature operation and at the same time having high sensitivity and selectivity to hydrogen gas.

In addition, the hydrogen gas sensor according to the present invention can measure hydrogen gas with high sensitivity and reliability by simultaneously detecting hydrogen by electrical method and hydrogen detection by optical method.

In addition, the hydrogen gas sensor according to the present invention has the advantage of being able to be driven with low power of 10 nW or less.

1 is a perspective view of a hydrogen gas sensor according to an embodiment of the present invention;
Figure 2 is a side view of the hydrogen gas sensor shown in Figure 1;
Figure 3 is a scanning electron microscope photograph of a polymer layer according to an embodiment of the present invention;
Figure 4 is a photograph showing the results of a hydrogen sensitivity test of the hydrogen gas sensor shown in Figure 1;
FIG. 5 is a graph of detection test results for each hydrogen concentration of the hydrogen gas sensor shown in FIG. 1.
Figure 6 is a graph showing the results of a repeated detection test of the hydrogen gas sensor shown in Figure 1;
FIG. 7 is a graph showing the results of a hydrogen gas selectivity detection test of the hydrogen gas sensor shown in FIG. 1.

Unless otherwise defined, the technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art to which this invention pertains, and the gist of the present invention is summarized in the following description and accompanying drawings. Descriptions of known functions and configurations that may unnecessarily obscure are omitted.

Additionally, as used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly dictates otherwise.

In addition, units used without special mention in this specification are based on weight, and as an example, the unit of % or ratio means weight % or weight ratio, and weight % refers to the amount of any one component of the entire composition unless otherwise defined. It refers to the weight percent occupied in the composition.

In addition, the numerical range used in this specification includes the lower limit and upper limit and all values within the range, increments logically derived from the shape and width of the defined range, all double-defined values, and the upper limit of the numerical range defined in different forms. and all possible combinations of the lower bounds. Unless otherwise specified in the specification of the present invention, values outside the numerical range that may occur due to experimental error or rounding of values are also included in the defined numerical range.

The term 'comprise' in this specification is an open description with the same meaning as expressions such as 'comprising', 'contains', 'has' or 'characterized by', and includes elements that are not additionally listed, Does not exclude materials or processes.

Conventional hydrogen gas sensors include sensors using catalytic combustion or heat wire, SiO ₂ , AlN metal oxide (nitride) semiconductors, and Schottky barrier diodes with a two-pole structure using bulk Pd and SiC and GaN for Pt. Sensors using , etc. are being developed. However, they are not only large in size and complex in structure, but also expensive. Additionally, since it operates at a high temperature of over 300℃, it not only consumes a lot of power but also has limitations such as low sensitivity to hydrogen.

In addition, sensors that detect hydrogen gas through hydrogen gas discoloration pigments that change color when exposed to hydrogen gas have been developed, but the color that changes depending on exposure to hydrogen gas is not high enough to be discerned with the naked eye, and the sensitivity is low, making it virtually impossible to detect hydrogen gas. It has the disadvantage of being difficult to use as a hydrogen gas sensor.

The hydrogen gas sensor according to the present invention includes a metal oxide layer; A first electrode and a second electrode positioned spaced apart from each other on the metal oxide layer; a metal nanoparticle layer located in an area where the first electrode and the second electrode are spaced apart; A polymer layer located on the metal nanoparticle layer; and a porous color conversion sensing layer located on the polymer layer and containing metal oxide, metal nanoparticles, and silicates, wherein, as a sensing unit, a metal oxide layer-metal nanoparticle layer-polymer layer-porous color conversion detection layer is included. By including a structure in which layers are stacked in order, room temperature operation is possible and at the same time, it can have high sensitivity and selectivity to hydrogen gas. In addition, hydrogen gas can be measured with high sensitivity and reliability by simultaneously detecting hydrogen by an electrical method and detecting hydrogen by an optical method such as discoloration.

1 to 2 show a hydrogen gas sensor according to an embodiment of the present invention.

Hereinafter, a hydrogen gas sensor according to an embodiment of the present invention will be described in detail with reference to the attached drawings. The attached drawings are provided as examples in order to sufficiently convey the technical idea of the present invention to technicians, and the present invention is not limited to the drawings presented below and may be embodied in many other forms.

Referring to Figures 1 and 2, the hydrogen gas sensor of the present invention includes a substrate 10, a metal oxide layer 15 located on the substrate 10; A first electrode 21 and a second electrode 23 spaced apart from each other on the metal oxide layer 15; a metal nanoparticle layer 30 located in an area where the first electrode 21 and the second electrode 23 are spaced apart; a polymer layer 50 located on the metal nanoparticle layer 30; and a porous color conversion sensing layer 70 located on the polymer layer 50 and containing metal oxide, metal nanoparticles, and silicate.

Specifically, the substrate 10 is not greatly limited as long as it is made of an insulating material, but is made of a transparent material so that the color change of the porous color conversion sensing layer 70 due to exposure to hydrogen gas can be easily detected with the naked eye. It is desirable. For example, the substrate 10 may be glass.

Preferably, the substrate 10 is a light-transmissive flexible substrate, and the metal oxide layer 15 may be located on the flexible substrate. For example, the flexible substrate may be flexible polyimide or flexible polyethylene terephthalate, but is not limited thereto. A hydrogen gas sensor including such a flexible substrate can be flexible, has a high risk of leakage, and can be installed in curved positions such as gas cylinders, pipes, valves, etc., thereby further increasing its usability. In addition, it can be installed in close contact with a position forming a curved surface, thereby detecting leakage of hydrogen gas and preventing the risk of leakage.

Alternatively, the substrate 10 may be a shrink film, and the metal oxide layer 15 may be located on the shrink film. Shrink film can be a material that is flexible and can be contracted by external forces such as heat. Specifically, it consists of one or more polymers selected from the group consisting of polyester (PET), oriented polystyrene (OPS), polyvinyl chloride (PVC), and polypropylene (PP). It could be material. A hydrogen gas sensor containing such a shrink film can be installed without being limited to the installation location by being transformed into a shape that corresponds to various installation locations such as pipes, bombs, and storage tanks. It is easily installed by shrinking, making installation very easy. You can.

As described above, the metal oxide layer 15-metal nanoparticle layer 30-polymer layer 50-porous color conversion sensing layer 70 is a sensing unit that detects hydrogen. Specifically, when hydrogen gas is exposed to the sensing unit while power is supplied to the first and second electrodes, the hydrogen gas is absorbed into the porous color conversion sensing layer 70 and can be detected with the naked eye through color change. The hydrogen gas that has passed through the porous color conversion sensing layer 70 reaches the metal oxide layer 15 and the metal nanoparticle layer 30 through the polymer layer 50. Hydrogen is adsorbed on (30) and the electrical properties change, allowing hydrogen to be detected.

The metal oxide layer 15 is made of metal oxide (MO _x ), and O _x may be selected from O ₁ to O ₁₀ depending on the degree of oxidation material, but is not limited thereto. The metal of the metal oxide layer 15 is not limited as long as it has hydrogen adsorption capacity. For example, the metal of the metal oxide layer 15 may be tin, and the metal oxide layer 15 may be a tin oxide (SnO ₂ ) layer. The tin oxide layer has a higher hydrogen adsorption rate compared to other metal oxide layers (15), making it possible to sense even low-concentration hydrogen gas.

The thickness of the metal oxide layer 15 may be 5 to 300 nm, specifically 30 to 200 nm, but is not limited thereto. However, within the above range, it can exhibit high hydrogen sensitivity compared to the thickness.

The metal nanoparticle layer 30 is located on the metal oxide layer 15 in an area where the first and second electrodes are spaced apart, and is located by discontinuous metal nanoparticles dispersed on the metal oxide layer 15. Specifically, metal nanoparticles may exist as zero-dimensional particles or aggregates of zero-dimensional particles. As a specific example, the metal nanoparticles may be made of aggregates with an average radius of 0.5 to 1 nm. It is advantageous for the metal to be palladium in terms of hydrogen adsorption capacity, and this metal nanoparticle layer 30 has both conductivity and excellent hydrogen adsorption capacity, so it can adsorb a large amount of hydrogen gas and enables highly sensitive sensing.

The thickness of the metal nanoparticle layer 30 is not limited as long as it is capable of hydrogen adsorption, but preferably the palladium nanoparticle layer has a thickness of 1 to 5 nm, specifically 2 to 4 nm.

As described above, when the metal of the metal nanoparticle layer 30 is palladium (palladium nanoparticle layer) and the metal of the metal oxide layer 15 is tin (tin oxide layer), it is very advantageous in terms of the hydrogen adsorption capacity of the hydrogen gas sensor. You can. In particular, hydrogen gas sensing is possible with high sensitivity as the palladium nanoparticle layer is located in a specific area, that is, an area where the first and second electrodes on the metal oxide layer 15 are spaced apart. The palladium nanoparticles are dispersed as discontinuous particles in the area. Preferably, the palladium nanoparticles are distributed only in a portion of the surface of the tin oxide layer in the area where the first electrode and the second electrode are spaced apart, so that the first electrode and the second electrode are dispersed as discontinuous particles. The surface of the tin oxide layer in the area where the two electrodes are spaced apart may include a first area where the palladium nanoparticle layer is located and a second area where the palladium nanoparticle layer is not located.

In detail, the upper area of the tin oxide layer exposed to the outside without palladium nanoparticles, that is, the area of the second region, is 50% of the total area of the tin oxide layer surface partitioned by the first electrode and the second electrode. It may be from 90% to 90%, preferably from 60% to 80%. The hydrogen gas sensor including the tin oxide layer and palladium nanoparticle layer as described above is capable of not only highly sensitive sensing, but also hydrogen sensing under various environmental conditions. Specifically, the hydrogen gas sensor is capable of highly sensitive hydrogen sensing even under temperatures of -50°C to 300°C and humidity of 10 to 80%.

The first electrode and the second electrode are used to measure changes in current or resistance, and are positioned spaced apart from each other on the metal oxide layer 15. Examples include, but are not limited to, copper, aluminum, nickel, titanium, silver, gold, platinum, and palladium, and any material used as a general electrode can be used. The thickness of the first and second electrodes may be 10 nm to 200 nm, specifically 50 nm to 150 nm, but is not limited thereto.

The polymer layer 50 allows hydrogen gas to selectively pass through, enabling more sensitive hydrogen gas sensing. Furthermore, the polymer layer 50 plays a role in protecting the sensing unit, such as preventing metal nanoparticles from leaving, and prevents hydrogen gas sensitivity from being reduced due to moisture, etc. when exposed to the outside for a long period of time. In other words, the polymer layer 50 can significantly improve the sensitivity, hydrogen selectivity, and physical and chemical stability of the sensing unit.

When the polymer layer 50 is formed on the metal oxide layer 15, the upper part of the metal oxide layer 15 exposed to the outside, that is, the second region, may be in direct contact with the polymer layer 50. Such a hydrogen gas sensor can further increase hydrogen selectivity.

The polymer of the polymer layer 50 may be an acrylate-based polymer or a vinyl-based polymer. Specifically, polymethacrylate, polymethylacrylate, polymethyl methacrylate (PMMA), polyethylacrylate, polyethylmethacrylate, and polyimide (PI). , polystyrene (PS), or mixtures thereof, but is not limited thereto.

In particular, the polymer of the polymer layer 50 may be a non-porous polymethyl methacrylate (PMMA) layer. This polymer layer 50 greatly increases hydrogen selectivity, enabling more reliable hydrogen gas sensing. Specifically, the polymer layer 50 made of non-porous polymethyl methacrylate can have higher hydrogen selectivity than porous polymethyl methacrylate, thereby improving sensitivity and reliability in hydrogen gas sensing.

The porous color conversion sensing layer 70 contains metal oxides, metal nanoparticles, and silicates, and is located on the outermost layer of the hydrogen gas sensor. It changes color when exposed to hydrogen gas, making it easy to visually determine whether or not exposure to hydrogen gas has occurred. make it possible In addition, in addition to the polymer layer 50 described above, hydrogen gas can be selectively transmitted through the metal oxide layer 15 and the metal nanoparticle layer 30, thereby further increasing the selectivity of the hydrogen gas sensor, and the polymer layer 50 Together with this, the hydrogen gas sensor can be protected from external factors such as moisture and air.

Specifically, metal oxide (MO _x ) may have O _x selected from O ₁ to O ₁₀ depending on the degree of oxidation material, but is not limited thereto.

The metal of the metal oxide may be one or more selected from the group consisting of zinc (Zn), titanium (Ti), molybdenum (Mo), and tungsten (W). For example, the metal oxide may be tungsten oxide (WO ₃ ). Such metal oxides, along with metal nanoparticles, which will be described later, can discolor with high sensitivity to hydrogen gas.

Metal nanoparticles, along with metal oxides, discolor in response to hydrogen gas, and it is advantageous for the metal of the metal nanoparticles to be palladium in discoloring hydrogen gas. Specifically, when the metal oxide is tungsten oxide and the metal nanoparticle is palladium nanoparticle, the tungsten oxide and metal nanoparticle form a mutually aggregated aggregate, and the discoloration activity ability to react with hydrogen gas can be increased. Specifically, the porous color conversion sensing layer 70 containing tungsten oxide and metal nanoparticles is relatively transparent before exposure to hydrogen, but may appear blue after exposure to hydrogen.

Silicate forms a porous sheet as it is crosslinked, and serves to uniformly disperse metal oxides, metal nanoparticles, and their aggregates in the entire area of the porous color conversion sensing layer 70, while stably fixing and supporting them. can do.

The silicate is not limited as long as it forms a three-dimensional porous structure, but is preferably manufactured through a condensation reaction of a C1-4 alkoxysilane compound. As an example, the alkoxysilane-based compound may be tetraethyl orthosilicate (TEOS).

The content of metal oxide, metal nanoparticles, and silicate contained in the porous color conversion sensing layer 70 is not specifically limited as long as it can exhibit hydrogen gas sensing ability. Specifically, the weight ratio of metal oxide: metal nanoparticle: silicate may be 1:0.5-1.5:0.1-0.5, specifically, 1:0.7-1.2:0.2-0.4.

In one embodiment of the present invention, the porous color conversion sensing layer 70 particularly contains tungsten oxide, palladium nanoparticles, and silicates, and thus has high selectivity and sensitivity to hydrogen gas, and is easily visible to the naked eye. It can have a color change high enough to make a judgment. Furthermore, such porous color conversion sensing layer 70 easily changes color even at room temperature when exposed to hydrogen gas, and has a hydrogen concentration of 10% or less, specifically, 5% or less, more specifically, low concentration hydrogen gas of 0.05 to 4%. The color change that can be easily discerned with the naked eye, that is, visibility, can be increased.

The method of detecting hydrogen gas of the present invention through the hydrogen gas sensor of the present invention described above can be accomplished by measuring the current or resistance before and after exposing the detection target gas to the detection unit, and at the same time detecting the color change with the naked eye. It can be measured. When measuring current or resistance, setting a standard by measuring the drain current (Ids(ref)) of the hydrogen gas sensor; Introducing a gas to be detected into a detection unit located between the first and second electrodes; A detection step of measuring the drain current (Ids(detect)) when the detection target gas is introduced; and analyzing the concentration of the detection gas using the measured drain current value. The detection gas may be detected based on the drain current value changed (increased) before and after introduction of the detection target gas. In contrast, of course, the detection gas can be detected with a changed resistance value rather than a drain current value that changes before and after the introduction of the detection target gas.

As the hydrogen gas sensor with the naked eye includes the above-mentioned detection unit, hydrogen gas can be measured with high sensitivity and reliability by simultaneously detecting hydrogen by an electrical method and detecting hydrogen by gas discoloration or optical methods.

At this time, the operating (detection) temperature of the hydrogen gas sensor may be in the range of -50 to 300 °C, specifically -10 to 200 °C, and more specifically 4 to 100 °C.

This hydrogen gas detection method can detect hydrogen gas having a concentration range of 0.1 to 100,000 ppm, specifically 1 to 80,000 ppm.

Hereinafter, the manufacturing method of the hydrogen gas sensor of the present invention will be described in detail.

a) forming a metal oxide layer on one side of the insulating layer; b) forming a first electrode and a second electrode spaced apart from each other on one surface of the metal oxide layer that is not in contact with the insulating layer; c) forming a metal nanoparticle layer with a thickness of 1 to 5 nm in the area where the first electrode and the second electrode are spaced apart; d) forming a polymer layer on the metal nanoparticle layer; e) preparing a coating solution by mixing a first solution containing metal oxide and metal nanoparticles and a second solution containing a C _1-4 alkoxysilane-based compound; and f) forming a porous color conversion sensing layer by applying and drying the coating solution on the polymer layer.

In the present invention, after step a), step b) and step c) may be performed sequentially, but depending on the ease of the process, step a), step c) and then step b) may be performed.

In detail, the step (hereinafter referred to as step a) of forming a metal oxide layer on one surface of the insulating layer may be performed by coating the insulating layer with a precursor solution containing a metal oxide precursor material. Specifically, the metal oxide may be tin oxide, and the precursor material may be any type as long as it is soluble in the solvent used, and may be used without limitation to specific precursors such as chloride series, acetate series, and halide. The solvent is a group consisting of 2-methoxyethanol, isopropanol, dimethylformamide, ethanol, methanol, acetylacetone, and dimethylamineborane. may include at least one. The molar concentration of the precursor material in the precursor solution may be 0.01M to 3M, specifically 0.025M to 0.2M, and more specifically 0.05 to 0.15M, but is not limited thereto.

The precursor solution may further include a solution stabilizer used in the art.

Step a) forms a precursor thin film by applying the precursor solution onto a substrate having the above-described insulating properties. The precursor solution can be applied by coating methods known in the art, such as spin coating, inkjet printing, and dip coating. Thereafter, heat treatment is performed on the precursor thin film of the substrate to form a metal oxide layer.

The heat treatment may be performed at 200°C to 500°C, specifically 280°C to 400°C, but is not limited thereto, and may be performed in 1st and 2nd stages at different temperatures.

In contrast, step a) may be performed without limitation by any method of forming a metal oxide layer known in the art, such as the ion beam method.

Thereafter, a step (hereinafter referred to as step b) of forming a first electrode and a second electrode spaced apart from each other on the metal oxide layer is performed.

Specifically, first, a shadow mask having openings in the shape of the first electrode and the second electrode is placed on the substrate on which the metal oxide layer is formed through step a). The shadow mask is a mask designed to selectively deposit deposition materials through the openings, making it possible to manufacture electrode parts with precise shapes. The shadow mask can be a metal shadow mask, a polymer shadow mask such as PDMS or PMMA, etc.

Next, metal is deposited using an electron beam on the substrate on which the shadow mask is placed, thereby forming a first electrode and a second electrode on the metal oxide layer. Metals include, but are not limited to, copper, aluminum, nickel, titanium, silver, gold, platinum, and palladium.

Next, a step (hereinafter referred to as step c) of forming a metal nanoparticle layer in the area where the first electrode and the second electrode are spaced apart is performed.

In step c), the metal nanoparticle layer may be a palladium nanoparticle layer, and the metal nanoparticle layer may be formed by depositing metal nanoparticles in the form of clusters and dispersed particles. Metal nanoparticles can be deposited using physical or chemical methods, preferably by sputtering, thermal evaporation, electron beam evaporation, electroplating, or spraying an aqueous metal solution on the sample surface, but are not limited to these. That is not the case.

In one aspect of the present invention, in step c), the metal nanoparticle layer may be formed by depositing only on a partial area of the surface of the metal oxide layer. Accordingly, the surface of the metal oxide layer in the area where the first electrode and the second electrode are spaced apart can be divided into a first area where the metal nanoparticle layer is located and a second area exposed to the outside because the metal nanoparticle layer is not located, It is possible to produce a hydrogen gas sensor with even better sensitivity.

Additionally, in step c), the metal nanoparticle layer may be formed to a thickness of 1 to 5 nm, preferably 2 to 4 nm.

Step d) is a step of forming a polymer layer on the first electrode, the second electrode, and the metal nanoparticle layer.

In step d), the polymer layer may be formed by coating a liquid polymer resin on the metal oxide layer and the metal nanoparticle layer. Specifically, the polymer resin may be an acrylate-based polymer resin or a vinyl-based polymer resin, but it is advantageous for it to be a polymethacrylate resin.

Preferably, the polymer resin can be applied through spin coating, spray coating, knife coating, or roll coating, but is not limited to this and can be coated by various methods known in the art. Polymer resin can be hardened in various ways depending on the type of resin. As a non-limiting example, polymethyl methacrylate (PMMA) resin can be cured by applying a solution dissolved in a solvent and then evaporating the solvent. Specifically, step d) may be performed including applying and drying polymethyl methacrylate dissolved in a solvent on the metal nanoparticle layer. At this time, the solvent may be a halogenated alkoxy benzene compound. Halogens can be chlorine, fluorine, and bromine. As an example, the halogenated alkoxy benzene compound may be anisole (CH₃OCH). The polymer layer produced using such a solvent is non-porous polymethyl methacrylate, and as described above, the selectivity of hydrogen gas can be greatly increased.

Step e) is a step of preparing a coating solution for forming a porous color conversion sensing layer, mixing a first solution containing metal oxide and metal nanoparticles and a second solution containing a C _1-4 alkoxysilane-based compound. To prepare a coating liquid.

Specifically, the first solution may be a sol mixed with a solvent and a metal oxide and metal nanoparticles, and may include a metal oxide, metal nanoparticles, and aggregates thereof. Metal nanoparticles in the first solution: The content of metal oxide is not limited as long as it can be uniformly mixed with each other. However, when the molar ratio of metal nanoparticles to metal oxide in the first solution is in the range of 1:10 to 100, specifically, 1:20 to 70, the visibility of the prepared porous color conversion sensing layer may be more excellent. . The second solution contains a C1-4 alkoxysilane-based compound and a solvent, and the C1-4 alkoxysilane-based compound may be tetraethyl orthosilicate (TEOS).

The solvent of the first solution and the second solution may be an organic solvent or an aqueous solution containing an organic solvent, for example, ethanol.

The mixing ratio of the first solution and the second solution can be appropriately adjusted according to the conditions required for the porous color conversion sensing layer to be manufactured. Specifically, the volume ratio of the first solution to the second solution mixed in step e) may be 1:0.01 to 1, specifically, 1:0.1 to 0.7, but is not limited thereto.

Step f) is a step of forming a porous color conversion sensing layer by applying and drying the coating solution prepared in step e) on the polymer layer. The coating solution can be applied through spin coating, spray coating, knife coating, roll coating, and dip coating, but is not limited to this and can be coated by various methods known in the art. Additionally, drying can result in curing by evaporating the solvent contained in the coating liquid.

In step f), as the coating solution is applied and dried on the polymer layer, the C _1-4 alkoxysilane-based compound may undergo a condensation reaction and be converted to silicate. Accordingly, a porous color conversion sensing layer with a three-dimensional cross-linked structure can be formed, and a porous color conversion sensing layer with high visibility in which metal oxides and metal nanoparticles are uniformly mixed and stably fixed can be formed.

(Manufacturing example)_Manufacture of porous color conversion sensing layer

First, tungsten (W) powder and 30% hydrogen peroxide (H ₂ 0 ₂ ) were added to 20 mL of ethanol at a molar ratio of 1:3, then stirred for 2 hours and centrifuged. The supernatant was separated and heated at 80°C for 3 hours, and then ethanol was added to obtain a 0.3 M WO ₃ precursor sol. Afterwards, palladium chloride (PdCl ₂ ) was added to the WO ₃ precursor sol so that the molar ratio of palladium:tungsten was 1:50 to prepare a first solution.

A mixture of tetraethyl orthosilicate (TEOS, 208.33, AR): aqueous ammonia (NH ₄ OH): 99% ethanol aqueous solution at a molar ratio of 1: 2: 40 was stirred for 1 hour. Afterwards, the ammonia water in the mixture was removed through a rotary evaporator so that the hydrogen ion concentration index (pH) of the mixture became neutral (pH7). The neutralized mixture was diluted with ethanol to a concentration of 0.4M, and then a second solution was prepared.

A coating solution was prepared by mixing the prepared first solution and the second solution at a volume ratio of 1:0.3.

(Example 1)

After spin coating (1000 rpm, 30 seconds) liquid polyimide (PI) resin on the cleaned silicon wafer substrate (thickness: 500-550um, resistivity: <0.005 ohm, SiO ₂ thickness: 3000A (Dry)), A flexible substrate was manufactured by baking while increasing the temperature step by step. Each step was performed at temperatures of 60, 80, 150, 230, and 300°C, and each step lasted 30 minutes, with the final temperature of 300°C lasting 1 hour.

A 0.1M SnCl ₂ solution using 2-methoxyethanol as a solvent was spin coated on the manufactured flexible substrate (3,000 rpm, 60 seconds) and then annealed at 400°C for 1 hour to form a SnO ₂ layer. Next, Al was deposited to a thickness of 90 nm and a width of 1000 μm through a shadow mask to form the first and second electrodes. At this time, the separation distance between the first and second electrodes was 200㎛. Next, Pd was deposited at a speed of 0.1Å/s using a thermal evaporator to have an average thickness of 3㎚. Afterwards, 4 mg/ml of PMMA (solvent anisole) was first spin-coated (500 rpm, 5 seconds), followed by second spin-coating (4000 rpm, 30 seconds), followed by heat treatment at 175°C for 10 minutes to form a PMMA layer. .

A scanning electron microscope image of the manufactured PMMA layer was confirmed and shown in Figure 3.

Finally, the coating solution prepared in the production example was spin-coated (800 rpm, 120 seconds) on the formed PMMA layer and then heat-treated at 50°C for 1 hour to manufacture a hydrogen gas sensor.

(Examples 2 to 5)

In Example 1, a hydrogen gas sensor was manufactured in the same manner as in Example 1, except that acetone, tetrahydrofuran, dimethylformamide, and chlorobenzene were used instead of anisole as the solvent for PMMA.

(Experimental Example 1) Detection test

Gas detection characteristics were measured using a semiconductor parametric analyzer (B15000A, Agilent) on an MSTECH probe station with an MFC system. The hydrogen gas sensor was placed approximately 1 cm below the gas tube and directly exposed to the required concentration of gas. The hydrogen gas detection test was conducted at room temperature. Using MFC, H2 gas (100ppm, 1%, 10% in N2) was mixed with dry air to produce hydrogen gas of the desired concentration. Detection characteristics were expressed by comparing the color change and current of the hydrogen gas sensor before and after exposure to hydrogen gas.

Referring to Figure 3, comparative photographs (SEM images) of the surfaces of PMMA layers of Examples 1 to 5 are shown. Referring to Figure 3, it was confirmed that Example 1 was non-porous.

Figure 4 is a photograph comparing the detection test results of the hydrogen gas sensor according to Example 1 with the naked eye. Specifically, Figure 4a) shows before the detection test, and Figure 4b) shows after the detection test results. Referring to FIG. 4, the hydrogen gas sensor has relatively high light transparency before exposure to hydrogen gas, but after exposure to hydrogen gas, it turns blue, and it was confirmed that hydrogen gas detection is possible with very high visibility. In particular, it was confirmed that hydrogen gas could be detected much faster than before, with a reaction time of less than 20 seconds.

Figure 5 is a graph showing a detection test (current change) for each hydrogen gas concentration of the hydrogen gas sensor according to Example 1. Specifically, referring to Figure 5, it was confirmed that hydrogen sensing was possible from low to high concentrations, so the sensing range was very wide.

Figure 6 shows a graph showing the results of a hydrogen gas repetitive sensitivity test of the hydrogen gas sensor according to Example 1. The hydrogen gas repeated sensitivity test was performed by measuring hydrogen gas at concentrations of 0.5%, 1%, and 4% five times using the method of the experimental example.

Referring to FIG. 6, it was confirmed that during repeated hydrogen sensor measurements of the hydrogen gas sensor according to Example 1, the sensing sensitivity did not deteriorate and the sensitivity was maintained at high sensitivity. Specifically, looking at the transmittance (%) change graph in FIG. 6, it is possible to detect hydrogen through color conversion with high sensitivity even in repeated measurements, and through the current comparison (Response, I _g /I _a ) graph, high sensitivity through electrical response. It was confirmed that hydrogen sensing was also possible.

Figure 7 is a graph showing comparison results of detection tests of hydrogen gas sensors according to Examples 1 to 5. Specifically, a detection test was performed by exposing each hydrogen gas sensor to 1000 ppm of hydrogen gas.

Referring to FIG. 7, in the case of Example 1, which was non-porous, it was confirmed that sensing of hydrogen gas was possible with very high sensitivity even though the same concentration of hydrogen gas was supplied.

As described above, the present invention has been described with specific details, limited embodiments, and drawings, but these are provided only to facilitate a more general understanding of the present invention, and the present invention is not limited to the above embodiments, and the present invention Anyone skilled in the art can make various modifications and variations from this description.

Accordingly, the spirit of the present invention should not be limited to the described embodiments, and the scope of the patent claims described below as well as all modifications that are equivalent or equivalent to the scope of this patent claim shall fall within the scope of the spirit of the present invention. .

1: Hydrogen gas sensor 10: Substrate
15: metal oxide layer 21: first electrode
23: second electrode 30: metal nanoparticle layer
50: polymer layer 70: color conversion sensing layer

Claims (16)

Metal oxide layer;
A first electrode and a second electrode positioned spaced apart from each other on the metal oxide layer;
a metal nanoparticle layer located in an area where the first electrode and the second electrode are spaced apart;
A polymer layer located on the metal nanoparticle layer; and
A hydrogen gas sensor comprising a porous color conversion sensing layer located on the polymer layer and containing metal oxide, metal nanoparticles, and silicate.
According to paragraph 1,
A hydrogen gas sensor, wherein the metal of the metal oxide of the porous color conversion sensing layer is at least one selected from the group consisting of zinc (Zn), titanium (Ti), molybdenum (Mo), and tungsten (W).
According to paragraph 1,
A hydrogen gas sensor, wherein the metal of the metal nanoparticles of the porous color conversion sensing layer is palladium.
According to paragraph 1,
The silicate is a hydrogen gas sensor prepared by a condensation reaction of a C _1-4 alkoxysilane-based compound.
According to paragraph 1,
A hydrogen gas sensor, wherein the weight ratio of the metal oxide: the metal nanoparticle: the silicate included in the porous color conversion sensing layer is 1:0.5-1.5:0.1-0.5.
According to clause 5,
The surface of the metal oxide layer in the area where the first electrode and the second electrode are spaced apart includes a first area where the metal nanoparticle layer is located and a second area where the metal nanoparticle layer is not located, a hydrogen gas sensor.
According to clause 6,
The area of the second region is 50% to 90% of the total area of the surface of the metal oxide layer partitioned by the first electrode and the second electrode.
According to paragraph 1,
A hydrogen gas sensor in which the polymer of the polymer layer is an acrylate-based polymer.
According to paragraph 1,
A hydrogen gas sensor wherein the polymer of the polymer layer is non-porous polymethyl methacrylate.
According to paragraph 1,
A hydrogen gas sensor wherein the metal oxide layer is located on a flexible substrate.
According to paragraph 1,
A hydrogen gas sensor wherein the metal oxide layer is located on a shrink film.
a) forming a metal oxide layer on one side of the insulating layer;
b) forming a first electrode and a second electrode spaced apart from each other on one surface of the metal oxide layer that is not in contact with the insulating layer;
c) forming a metal nanoparticle layer with a thickness of 1 to 5 nm in the area where the first electrode and the second electrode are spaced apart;
d) forming a polymer layer on the metal nanoparticle layer;
e) preparing a coating solution by mixing a first solution containing metal oxide and metal nanoparticles and a second solution containing a C _1-4 alkoxysilane compound; and
f) forming a porous color conversion sensing layer by applying and drying the coating solution on the polymer layer.
According to clause 12,
In step f), the C _1-4 alkoxysilane-based compound is converted to silicate through a condensation reaction.
According to clause 12,
In step c), the metal nanoparticle layer is formed by depositing on a partial area of the surface of the metal oxide layer.
According to clause 12,
Step d) includes applying and drying polymethyl methacrylate dissolved in a solvent on the metal nanoparticle layer.
According to clause 15,
In step d) above,
A method of manufacturing a hydrogen gas sensor, wherein the solvent is a halogenated alkoxy benzene compound.