Hydrogen detection element and method for manufacturing the same

Abstract

The present invention provides a hydrogen detection element characterized by its flexibility, ability to operate at room temperature without requiring heating by a heater or the like, and the property of changing both its electrical conductivity and optical transmission spectrum upon detecting hydrogen. [Solution] A hydrogen detection element is provided comprising platinum-supported tungsten oxide particles, a conductive polymer exhibiting P-type conductivity, and a polymer having an electron-withdrawing functional group.

Description

[Technical Field]

[0001] This disclosure relates to a hydrogen detection element made of an organic-inorganic composite material that enables hydrogen gas detection, and to a method for manufacturing the same. [Background technology]

[0002] Hydrogen, used in fuel cells and other applications, is in high demand as a next-generation energy source. Furthermore, compared to fossil fuels such as petroleum, hydrogen has a higher energy density and lower environmental impact, making it a significant contributor to achieving a decarbonized society. However, hydrogen is a colorless, odorless gas and poses an explosive risk in the air at concentrations ranging from approximately 4 to 74 volume percent. Additionally, it has a high diffusion rate in various materials and the atmosphere compared to flammable gases such as methane, making it prone to escape. Therefore, sensors to detect hydrogen gas leaks are essential to realize a society that safely utilizes hydrogen as an energy source.

[0003] <Conventional hydrogen detection element> Several types of hydrogen detection elements have already been developed. Catalytic combustion type hydrogen detection elements are widely used. Patent Document 1 discloses a hydrogen detection element that utilizes a solid electrolyte containing an ion conductor. Furthermore, Patent Document 2 discloses a hydrogen concentration measuring device that combines a process of measuring hydrogen concentration using the electrical resistance of a detection film containing a metal oxide film and a process of measuring hydrogen concentration using the transmitted light intensity of the detection film. Patent Document 3 discloses a chromic sheet containing an organic material having a siloxane skeleton and a chromic oxide, which changes color upon exposure to hydrogen gas. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 4100984 [Patent Document 2] Patent No. 6709429 [Patent Document 3] Japanese Patent Publication No. 2017-181996 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, in the case of catalytic combustion type hydrogen detection elements and hydrogen detection elements using solid electrolytes containing ion conductors, the detection part needs to be heated to a temperature of, for example, 300°C or higher by means of a heater, which has the problem of high energy consumption. In addition, in the case of hydrogen detection elements using solid oxide films, the shape cannot be flexibly changed, which presents the problem of difficulty in attaching them to the complexly curved pipes and valves used for transporting hydrogen.

[0006] Furthermore, the chromic sheet having a siloxane skeleton, as disclosed in Patent Document 3, is flexible and can change shape flexibly, making it suitable for curved sections of gas pipes and the like. Although it has the advantage of being easy to install, it only detects hydrogen leakage by changing color, and it is not possible to detect hydrogen by detecting changes in electrical properties such as electrical resistivity, or to quantitatively measure hydrogen concentration. Sensory testing using color changes has the advantage of being relatively inexpensive and easy to perform, but it is difficult to quantify hydrogen concentration using only color changes.

[0007] Furthermore, for example, Patent Document 2 discloses an example in which tungsten trioxide (Pt / WO3) supported with polymer-free platinum is used as a hydrogen detection film, and hydrogen is detected by measuring its resistivity. This utilizes the property that resistivity decreases upon introduction of hydrogen. In other words, in an atmosphere without hydrogen, the resistance is high and current does not flow easily, but when hydrogen is detected, current begins to flow. This method is equivalent to a so-called normally open (A) contact switch, and there is a risk that, for example, a break in the wire due to aging deterioration may go unnoticed, and hydrogen leakage may not be detected.

[0008] This disclosure has been made in view of the problems of the conventional hydrogen detection elements described above, and aims to provide a hydrogen detection element that is flexible, can operate at room temperature and therefore does not require a heater, and is characterized by having both the property of increasing electrical resistivity when detecting hydrogen and the property of changing the light transmission spectrum. [Means for solving the problem]

[0009] The following are examples of specific means for solving the problem: <1> An exposure hydrogen detection element comprising platinum-supported tungsten oxide particles, a conductive polymer compound exhibiting P-type conductivity, and a polymer compound having an electron-withdrawing functional group. <2> A hydrogen detection element characterized in that the conductive polymer compound exhibiting P-type conductivity is poly(3,4-ethylenedioxythiophene). <3> The hydrogen detection element is characterized in that the polymer compound having the electron-withdrawing functional group is poly(styrene sulfonic acid). <4> The aforementioned <1> or <3> A hydrogen detection element as described in any one of the items, Furthermore, at least two electrodes connected to the hydrogen detection element and an electrical characteristic measuring device utilizing the electrodes, and / or A hydrogen sensor characterized by comprising an optical measuring device for measuring the optical characteristics of the hydrogen sensing element. <5> A method for manufacturing a hydrogen detection element, characterized by comprising the step of mixing an aqueous dispersion of platinum-supported tungsten oxide particles with an aqueous dispersion of a conductive polymer compound exhibiting P-type conductivity and a polymer compound having an electron-withdrawing functional group. <6> A method for producing a hydrogen detection element, characterized in that the conductive polymer compound exhibiting P-type conductivity is poly(3,4-ethylenedioxythiophene), and the polymer compound having an electron-withdrawing functional group is poly(styrenesulfonic acid). <a1> A hydrogen detection element comprising platinum-supported tungsten oxide particles, a conductive polymer exhibiting P-type conductivity, and a polymer having electron-withdrawing functional groups, characterized by utilizing the property that its light transmittance and electrical conductivity change upon exposure to hydrogen. <a2> The conductive polymer exhibiting the P-type conductivity is characterized by being poly(3,4-ethylenedioxythiophene). <1> The hydrogen detection element described. <a3> The polymer having the electron-withdrawing functional group is characterized by being poly(styrene sulfonic acid). <a1>or <a2>The hydrogen detection element described. <a4> <a1>or <a3>A hydrogen sensor comprising a hydrogen detection element as described in any one of the above, and further comprising at least two electrodes connected to the hydrogen detection element, an electrical characteristic measuring device utilizing the electrodes, and an optical measuring device for measuring the optical characteristics of the hydrogen detection element. <a5> The method is characterized by comprising the step of mixing an aqueous dispersion of platinum-supported tungsten oxide particles with an aqueous dispersion of a conductive polymer exhibiting P-type conductivity and a polymer having an electron-withdrawing functional group. <a1>or <a3>A method for manufacturing a hydrogen detection element according to any one of the items. <a6> The conductive polymer exhibiting the P-type conductivity is poly(3,4-ethylenedioxythiophene), and the polymer having the electron-withdrawing functional group is poly(styrenesulfonic acid). <a5>The manufacturing method of the described hydrogen detection element.

Advantages of the Invention

[0010] According to one embodiment of the present invention, there are provided a hydrogen detection element and a manufacturing method thereof, which include tungsten oxide particles supporting platinum, a conductive polymer showing P-type conductivity, and a polymer having an electron-withdrawing functional group, and utilize the property that the light transmittance and the electrical conductivity change upon exposure to hydrogen.

Brief Description of the Drawings

[0011] [Figure 1] FIG. 1 is a flowchart of a method for fabricating a Pt / WO3-PEDOT / PSS thin film. [Figure 2] FIG. 2 is a graph showing the relationship between the number of spin coating times and the film thickness. [Figure 3] FIG. 3 is a graph showing the visible to infrared transmission spectrum of Pt / WO3-PEDOT / PSS. [Figure 4] FIG. 4 is a graph showing the change in the light transmittance at a wavelength of 800 nm of Pt / WO3-PEDOT / PSS upon alternating exposure to 100% hydrogen gas and synthetic air. [Figure 5] FIG. 5 is a graph showing the change in the electrical resistance of Pt / WO3-PEDOT / PSS upon alternating exposure to 100% hydrogen gas and synthetic air. [Figure 6] FIG. 6 is a graph showing the change in color of Pt / WO3-PEDOT / PSS upon exposure to 100% hydrogen gas and synthetic air.

Modes for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present disclosure will be described.

[0013] In the present disclosure, “~” indicating a numerical range is used to mean including the numerical values described before and after it as the lower limit value and the upper limit value.

[0014] In the numerical ranges described in stages in this disclosure, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit of that range may be replaced with the values ​​shown in the examples.

[0015] In this disclosure, when referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, it means the total amount of all multiple components present in the composition unless otherwise specified.

[0016] Compounds that are not specified as substituted or unsubstituted in this disclosure may have any substituents, as long as they do not impair the effects described in this disclosure.

[0017] In this disclosure, a preferred combination of embodiments is a more preferred embodiment. In this disclosure, two or more preferred embodiments may be combined in any combination.

[0018] <Gas chromism of platinum-supported tungsten oxide particles (Pt / WO3)> Tungsten trioxide (Pt / WO3) supported with a Pt catalyst undergoes a redox reaction depending on the ambient gas, resulting in a reversible color change. This reaction is called gas chromism.

[0019] The mechanism by which hydrogen changes color is as follows: Hydrogen molecules are atomized by a Pt catalyst to form WO3, which then ionizes at the surface. When protons are introduced into the lattice, electrons localize in the d orbitals of W as charge compensation. 6+ From W 5+ It changes to this. Thus, W with oxygen sandwiched in between 6+ and W 5+ A mixed valence state is created. At this time, W 5+ The electrons localized there gain energy through light absorption, and then other W 6+ Go to site. This intervalence charge transfer results in broad absorption in the visible to infrared region.

[0020] Furthermore, dd transitions within the d orbital of W also cause light absorption, forming a light absorption band (600-800 nm) in the visible light region and exhibiting the complementary color blue.

[0021] Although WO3 is an insulator, protons and electrons inserted into the WO3 lattice by gas chromism act as conduction carriers, so colored HWO3 exhibits electrical conductivity. It is also known to exhibit ionic conductivity, but electrons are 10 times more numerous than ions. 3 ~10 6 Because electrons move at roughly twice the speed of electrons, it is thought that they are responsible for almost all of the electrical conduction.

[0022] Furthermore, in an atmosphere where oxygen is present, blue-colored Pt / WO3 undergoes a decolorization reaction, extracting protons and electrons inserted into the WO3 lattice. Therefore, when hydrogen gas disappears from the atmosphere, Pt / WO3 returns to its original color in air and reverts to its insulator state. By utilizing gas chromism, Pt / WO3 is a material that can detect the presence of hydrogen through changes in optical and electrical properties caused by coloration.

[0023] <Method for producing platinum-supported tungsten oxide particles> Next, the method for producing Pt / WO3 particles is shown below. The morphology and particle size distribution of Pt / WO3 greatly affect the performance of hydrogen detection elements, making its manufacturing method crucial. For example, if the particle size is too large, problems arise such as reduced light transmittance due to Mie scattering even after compounding with polymers. Therefore, it is necessary to adjust the particle size distribution to the optimal level for hydrogen detection using a bead mill or similar device.

[0024] For convenience, tungsten oxide is expressed as WO3 in this disclosure, but the chemical ratio of tungsten to oxygen does not necessarily have to be 1:3; a non-stoichiometric ratio may also be used.

[0025] Pt / WO3 was synthesized using a known sol-gel method. Tungsten hexachloride (WCl6) was used as the tungsten source in the sol-gel method. WCl6, being a chloride, has high solubility in polar organic solvents such as ethanol and is characterized by high reactivity in alkoxide synthesis. However, the tungsten source for the present invention is not limited to chlorides; any tungsten compound that can be used in the sol-gel method is acceptable.

[0026] <Poly(3,4-ethylenedioxythiophene) / Poly(styrenesulfonic acid) (PEDOT / PSS)> Poly(3,4-EthyleneDiOxyThiophene) / Poly(4-StyreneSulfonate) (PEDOT / PSS) is known as a highly conductive polymer with high electrical conductivity and is a p-type semiconductor with high transparency, high heat resistance, and high processability.

[0027] The conductive polymer PEDOT generates cations at a rate of one per three to four thiophene rings due to excess oxidizing agents during polymerization. These cations are stabilized by Coulomb interactions with the dissociated sulfo groups of PSS. In PEDOT / PSS, these cations act as carriers that move within the molecule, thus exhibiting conductivity.

[0028] Furthermore, PEDOT / PSS is generally stable in an aqueous dispersion. In water, it exists as a stable colloidal tertiary structure with crystalline PEDOT as the core and hydrophilic PSS covering it as a shell. When this aqueous dispersion is applied and dried to form a film, a higher-order structure is formed in which insulating PSS covers the surface of the crystalline PEDOT core. This inhibits carrier (hole) transport between colloids, suppressing electrical conductivity.

[0029] On the other hand, when ethylene glycol (EG) or the like is added to an aqueous dispersion to form a film, the crystallization of PEDOT is promoted, and at the same time, the PSS on the colloidal surface dissolves, causing changes in the higher-order structure such as contact between cores. This promotes carrier transport between colloids, and significantly improves electrical conductivity. For this reason, PEDOT / PSS is a suitable conductive polymer because it can exhibit conductivity in the polymer itself through (primary) doping, which involves the transfer of electrons, and then further improve the conductivity of the film through secondary doping, which changes the higher-order structure.

[0030] As described above, the fact that PEDOT / PSS can be processed as a gel or as a dispersion solution allows for various applications as embodiments of the present invention.

[0031] The hydrogen detection performance of the gel particles themselves can be adjusted by controlling factors such as the weight ratio of PEDOT to PSS, particle size, degree of polymerization of PEDOT, and length of the PSS chain.

[0032] Furthermore, in the preparation of the dispersion solution, it is possible to adjust the solution properties such as viscosity, change the deposition status of PEDOT units related to conductivity, and modify the solution properties, allowing for customization according to the application.

[0033] Furthermore, considering the hydrogen detection mechanism in the present invention, it is sufficient to increase the resistance value by supplying electrons to a polymer exhibiting P-type conductivity, that is, electrical conductivity due to holes. For this reason, the combination of polymer materials is not limited to PEDOT / PSS. In other words, the polymer material exhibiting P-type conductivity may be polyacetylene, poly(p-phenylene), poly(p-phenylene vinylene), polyaniline, graphene, polypyrrole, polyaniline, poly(p-phenylene), polyfluorene, polythiophene, poly(p-phenylene vinylene), polythienylene vinylene, etc.

[0034] In addition, the polymer having an electron-withdrawing functional group may be an aromatic hydrocarbon polymer, a heterocyclic polymer, etc. having a halogeno group such as a nitro group, a cyano group, a carboxy group, a chloro group, a bromo group, etc.

[0035] <Pt / WO3-PEDOT / PSS Hybrid Hydrogen Sensor> In the present disclosure, by hybridizing Pt / WO3, which is an inorganic material having the above-described gasochromism characteristics, with PEDOT / PSS, which is an organic material excellent in light transmittance, processability, and heat resistance in the visible to infrared light region, a hydrogen sensing element having flexibility and capable of optical detection and electrical detection is provided.

[0036] When Pt / WO3 and PEDOT / PSS are combined, upon hydrogen exposure, electrons of WO3 and holes of PEDOT are combined, and detection by a change in electrical resistance due to a decrease in carriers and detection by coloring can be made compatible. That is, in addition to the color change, since the excellent electrical physical properties of Pt / WO3 can be applied, it can be applied to a hydrogen sensor capable of quantitatively determining the hydrogen concentration as well as detecting hydrogen at a dilute concentration.

Example

[0037] <Preparation of Pt / WO3 Particle Dispersion Liquid> In a dry nitrogen atmosphere, 3.00 g of tungsten hexachloride (WCl6) was dissolved in 30 mL of ethanol, and 0.038 g of chloroplatinic acid hexahydrate (H2PtCl6·6H2O) was dissolved in 12 mL of ethanol (that is, the molar ratio was approximately Pt:W = 1:100), and stirred for 90 minutes to promote the alkoxylation reaction. Since tungsten hexachloride is easily oxidized by oxygen in the air and chloroplatinic acid has deliquescence, the synthesis reaction was carried out in dry nitrogen.

[0038] Next, the tungsten solution and the platinum-containing solution were mixed and stirred for 60 minutes to prepare a sol solution.

[0039] Next, the prepared sol solution was dried in an electric furnace at 120 °C for 12 hours, and then heat-treated at 400 °C for 6 hours to crystallize and obtain a Pt / WO3 powder sample. 0.4 g of this Pt / WO3 powder was mixed with 30 mL of distilled water and 20 mL of 0.8 mmφ zirconia beads, and bead mill treatment was performed at a rotation speed of 1500 rpm for 2 hours using a batch-type bead mill (RMB-01 manufactured by Imex Co., Ltd.) to finely pulverize it.

[0040] The selection of the solvent to be mixed at this time is extremely important. Since the PEDOT / PSS to be mixed later is an aqueous dispersion, distilled water is used as the solvent to obtain a good mixing state.

[0041] Next, a dispersant was added to the suspension after bead mill treatment and stirred. Then, in order to remove the undispersed particles, the Pt / WO₃ fine particle dispersion suspension was centrifuged at a rotation speed of 4800 rpm for 30 minutes using a tabletop centrifuge (Tabletop Centrifuge 4200 manufactured by Kubota Shokai Co., Ltd.), and the precipitate was removed to obtain a preferable Pt / WO₃ fine particle aqueous dispersion.

[0042] <Fabrication of Pt / WO₃-PEDOT / PSS Organic-Inorganic Hybrid Thin Film> The Pt / WO₃ fine particle aqueous dispersion and the aqueous dispersion of PEDOT / PSS were mixed in a predetermined amount, stirred, and then coated and dried on a glass substrate using a spin coater (K-359-S-1 manufactured by Kyowa Riken Co., Ltd.).

[0043] The glass substrate was processed into a circular shape with a diameter of 55 mmφ and immersed in diluted RBS-25 industrial liquid detergent for ultrasonic cleaning. After fixing the glass substrate to the spin coater, the Pt / WO₃-PEDOT / PSS aqueous dispersion was dropped and spin coating was performed. The spin coating conditions were 1st step: 500 rpm for 10 seconds, 2nd step: 1000 rpm for 20 seconds. In the 1st step, the Pt / WO₃-PEDOT / PSS aqueous dispersion was uniformly coated on the glass substrate, and in the 2nd step, the excess solution was removed.

[0044] After each coating, the material was dried on a 200°C hot plate for 10 minutes. The coating and drying process was repeated, for example, five times to obtain a Pt / WO3-PEDOT / PSS hybrid thin film. Figure 1 shows a flowchart of the Pt / WO3-PEDOT / PSS thin film fabrication method. Figure 2 shows the relationship between the number of spin-coating and drying cycles and the film thickness measured using a contact step gauge. An XP-1 contact step gauge from AMBIOS TECHNOLOGY was used.

[0045] In the above embodiment, for simplicity, the film was formed into a thin film by repeatedly spin-coating and drying the glass substrate, and experimental evaluation was performed while the film remained attached to the glass substrate. However, the Pt / WO3-PEDOT / PSS film can be easily peeled off the glass substrate, and it can also be used as a single layer film by mounting it on a frame made of aluminum or the like.

[0046] Furthermore, for industrial implementation, spin coating is not necessary. For example, a bulk resin body may be formed by mixing a Pt / WO3 aqueous suspension and a PEDOT / PSS suspension in a properly designed batch-type reaction vessel and drying it. Alternatively, it may be processed into a film, for example, with a thickness of about 0.1 mm to 10 mm, by means of roll molding or other methods, as needed.

[0047] <Evaluation Results> <Changes in absorption spectrum> Figure 3 shows the transmission spectrum of the Pt / WO3-PEDOT:PSS thin film. A V-630 spectrophotometer manufactured by JASCO Corporation was used to measure the transmission spectrum. Under H2 gas exposure, absorption was observed in the wavelength region centered around approximately 900 nm.

[0048] The thin film samples after deposition appeared slightly dark due to light absorption by PEDOT:PSS, but it was visually confirmed that they changed to blue under H2 gas exposure. Since the transmission spectrum measurements of the thin films showed a significant change in transmittance at long wavelengths of visible light, and because the development of a sensor capable of visually detecting hydrogen leakage is also a goal, light with a wavelength of 800 nm was used for optical property evaluation.

[0049] Figure 4 shows the transmittance of Pt / WO3-PEDOT:PSS thin films exposed to 100% H2 gas and synthetic air. The transmittance of a thin film sample fabricated on a glass substrate was 75% at 800 nm under synthetic air conditions, but decreased to 46.5% upon H2 gas exposure. The transmittance recovered when the atmosphere was changed back from H2 gas to synthetic air.

[0050] <Changes in electrical resistance> To measure electrical resistance, a pair of opposing comb-shaped gold electrodes were attached to the Pt / WO3-PEDOT:PSS film in close contact. The spacing between the teeth of each pair of comb electrodes was 0.5 mm, and the total length of the overlapping portion of the teeth of each pair of comb electrodes was 8 mm. The resistance between these electrodes was measured using an ADCMT 7352E digital multimeter.

[0051] Figure 5 shows the change in resistance of the Pt / WO3-PEDOT:PSS film (film thickness: 150 nm). The electrical resistance was 5.3 kΩ under synthetic air, but increased to 19.4 kΩ upon exposure to H2 gas.

[0052] Herein lies one of the features of the present invention, which is clearly demonstrated. For example, Patent Document 2 discloses an example in which polymer-free Pt / WO3 is used as a hydrogen detection film and hydrogen is detected by measuring its resistivity. This utilizes the property that resistivity decreases upon introduction of hydrogen. In other words, in an atmosphere without hydrogen, the resistance is high and current does not flow easily, but when hydrogen is detected, current begins to flow. This method is equivalent to a so-called normally open (A) contact switch, and there is a risk that, for example, a break in the wire due to deterioration over time may not be noticed, and hydrogen leakage may not be detected.

[0053] In contrast, the hydrogen detection element of the present invention is a method corresponding to a so-called B-contact switch in which the resistance changes in the higher direction by the introduction of hydrogen, and it is possible to configure a safer hydrogen detector without the risk of hydrogen leakage detection errors due to disconnection.

[0054] <Quantification of hydrogen concentration> The evaluation of the color change by visual inspection is difficult to quantify, for example, due to individual differences. Therefore, it is possible to measure the transmittance or reflectance at one or more wavelengths in the visible to infrared light region of, for example, wavelengths of 700 nm to 2000 nm and convert it to the hydrogen concentration. Furthermore, in the hydrogen detection element of the present invention, since hydrogen can also be detected by the change in electrical resistance, for example, by creating a calibration curve between the electrical resistance value and the hydrogen concentration in advance, it is possible to quantify the hydrogen concentration from the electrical resistance value.

[0055] <Characteristics of response speed to hydrogen> WO3 becomes H X Since conduction electrons are generated by becoming WO3, it is considered that the carrier concentration decreased by combining with the holes of PEDOT:PSS, resulting in an increase in electrical resistance. Compared with the optical response evaluated by the light transmittance, the electrical resistance value showed a faster response to the change in the atmosphere. This is because the transmitted light passes through the entire film from the surface to the deep part of the film, reflecting that it takes time for the diffusion and desorption of hydrogen from the deep part, while the electrical resistance is largely affected by the conductivity of the part relatively close to the surface of the film.

[0056] Therefore, the hydrogen detection element according to the present invention can be applied in a hybrid manner, for example, detecting rapid hydrogen leakage by the change in electrical resistance and confirming slow leakage by the color change with the naked eye or detecting it by optical means.

[0057] As shown in FIGS. 4 and 5, it has been demonstrated that the optical response and the electrical response as the hydrogen gas detection performance of the Pt / WO3-PEDOT:PSS thin film are reversible and it is a hydrogen detection element that can be repeatedly used. <000026

[0058] <Visual confirmation of changes> Figure 6 shows photographs of the Pt / WO3-PEDOT:PSS thin film under a hydrogen gas atmosphere and a dry air atmosphere. The Pt / WO3-PEDOT:PSS thin film is colorless under dry air and exhibits a blue color under a hydrogen gas atmosphere. Such a visually observable color change is also reversible.

[0059] In other words, the hydrogen detection element of the present invention has the advantage of enabling early visual detection of hydrogen leaks even in areas where electrodes are not attached, i.e., areas that are not electrically monitored, by applications such as attaching it to long pipes. < / a4>

Claims

1. An exposure hydrogen detection element comprising platinum-supported tungsten oxide particles, a conductive polymer compound exhibiting P-type conductivity, and a polymer compound having an electron-withdrawing functional group.

2. The hydrogen detection element according to claim 1, characterized in that the conductive polymer compound exhibiting P-type conductivity is poly(3,4-ethylenedioxythiophene).

3. The hydrogen detection element according to claim 1, characterized in that the polymer compound having the electron-withdrawing functional group is poly(styrenesulfonic acid).

4. A hydrogen detection element according to any one of claims 1 to 3, Furthermore, at least two electrodes connected to the hydrogen detection element and an electrical characteristic measuring device utilizing the electrodes, and / or A hydrogen sensor characterized by comprising an optical measuring device for measuring the optical characteristics of the hydrogen sensing element.

5. A method for manufacturing a hydrogen detection element, characterized by comprising the step of mixing an aqueous dispersion of platinum-supported tungsten oxide particles with an aqueous dispersion of a conductive polymer compound exhibiting P-type conductivity and a polymer compound having an electron-withdrawing functional group.

6. The method for producing a hydrogen detection element according to claim 5, characterized in that the conductive polymer compound exhibiting P-type conductivity is poly(3,4-ethylenedioxythiophene), and the polymer compound having an electron-withdrawing functional group is poly(styrenesulfonic acid).

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