JP2010197074A - Hydrogen gas sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogen gas sensor that has improved hydrogen gas selectivity, can be easily handled, and has small power consumption without performing any purge operation. <P>SOLUTION: The substrate-type hydrogen gas sensor 1 includes: a second electrode layer 4b formed on a substrate 10; a proton conductive layer 2 by a solid polymer electrolyte membrane stacked on the second electrode layer 4b; a catalyst layer 3 stacked on the proton conductive layer 2; and a first electrode layer 4a having permeability stacked on the catalyst layer 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a hydrogen gas sensor that detects a hydrogen gas concentration in a gas phase or a liquid phase.

  In constructing a hydrogen energy system typified by a fuel cell, there is an extremely high need for a hydrogen gas sensor that accurately detects the hydrogen concentration. When measuring the hydrogen concentration in the gas phase or liquid phase, There is a need for a hydrogen gas sensor that does not require application of high temperature and that eliminates the need for a diaphragm and an electrolytic solution to prevent these deteriorations and enables reduction in size and weight.

  In response to such a purpose, Patent Document 1 includes a sensitive part that changes electrical resistance when it comes into contact with hydrogen, and the sensitive part is formed of a hydrogen-absorbing simple metal or alloy, or nanocarbon. A hydrogen sensor formed of a material selected from a material, a hydrogen-absorbing simple metal, and a hydrogen-absorbing alloy has been proposed.

Patent Document 2 proposes a hydrogen gas sensor in which a pair of electrodes for measuring electrical resistance is provided on a sensitive part made of a metal oxide semiconductor such as TiO ₂ , SrTiO ₃ , or BaTiO ₃ .

JP 2004-125513 A JP 2002-071611 A

  However, the hydrogen sensor described in Patent Document 1 detects an electric resistance value that changes when hydrogen gas is occluded in a sensitive part formed of a hydrogen-absorbing single metal or alloy. Since the state in which hydrogen is occluded is maintained, dynamic fluctuation cannot be followed, and a purge operation is required to release the occluded hydrogen from the sensitive part in preparation for the next measurement. .

  In addition, the hydrogen gas sensor described in Patent Document 2 detects changes in the electrical resistance of the metal oxide semiconductor accompanying the reaction between oxygen adsorbed on the surface and hydrogen gas, so that sufficient adsorption and desorption of oxygen molecules is achieved. Therefore, it is necessary to provide a heating element for heating the element temperature of the sensitive part to about 400 ° C. Therefore, there is a problem that power consumption increases and a heat-resistant structure needs to be provided. In addition to hydrogen gas, it responds to flammable gases such as methane gas and carbon monoxide gas, and gas selection There was also a problem of lack of sex.

  In addition, it is conceivable to construct a hydrogen gas sensor using the power generation characteristics of MEA (Membrane Electrode Assembly) generally used in fuel cells. MEA is a double-sided polymer electrolyte membrane. Further, since a catalyst electrode using an expensive metal such as platinum is formed, further improvement has been desired from the viewpoint of suppressing the cost of components.

  In view of the above problems, an object of the present invention is to provide a hydrogen gas sensor having good hydrogen gas selectivity, easy handling, and low power consumption without performing a purge operation.

  In order to achieve the above-mentioned object, the first characteristic configuration of the hydrogen gas sensor according to the present invention includes a proton conductive layer, a proton conductive layer, and a catalyst layer as described in claim 1 of the claims. The first electrode layer to be bonded and the second electrode layer to be bonded to the proton conductive layer are stacked on the substrate.

  As shown in FIG. 23, the inventors of the present application are made of a metal or the like that exhibits a catalytic function by contacting hydrogen gas on at least one side surface of a base material 2 composed of a solid polymer electrolyte having proton conductivity. A self-supporting membrane-type hydrogen gas sensor that can output in response to hydrogen gas is formed by forming the catalyst layer 3 and joining the electrodes 4 (4a, 4b) so as to sandwich the substrate 2 and the catalyst layer 3 therebetween. We have the knowledge that we can do it.

  Such a self-supporting membrane type hydrogen gas sensor includes a film forming process in which a polymer electrolyte solution, which is a raw material of a base material, is poured into a mold to form a cast film, and a peeling process in which the film is removed from the mold after drying the solvent. A step of supporting the catalyst on the surface of the peeled membrane, a cutting step of cutting the membrane carrying the catalyst into an appropriate size, and an electrode attaching step of joining the electrodes to both sides of the cut membrane Necessary.

  However, the film cannot be easily peeled off from the mold, and there is a problem that the film is damaged. It is necessary to increase the film thickness to ensure the mechanical strength so that the film is not damaged in the cutting process. Various problems are inherent such as a problem that there is a limitation in miniaturization and a problem that the manufacturing process is complicated and productivity is lowered, such as attaching electrodes one by one to the cut film pieces.

  Further, when the membrane piece bends due to mechanical vibration or the like, the contact resistance with the electrode may fluctuate and the output may fluctuate, and it is necessary to improve output stability and productivity and further reduce the size.

  According to the configuration described above, the proton conductive layer, the first electrode layer bonded to the proton conductive layer and the catalyst layer, and the second electrode layer bonded to the proton conductive layer are stacked on the substrate. As a result, the above-described peeling process and electrode mounting process are not required, and since the structure is built on a substrate having mechanical strength, even if the proton conductive layer is thinned, the cutting process may be damaged. A small hydrogen gas sensor can be efficiently produced without incurring.

  As a first aspect, such a hydrogen gas sensor includes a second electrode layer formed on a substrate, a proton conductive layer stacked on the second electrode layer, and a catalyst layer stacked on the proton conductive layer. The first electrode layer laminated on the catalyst layer can be provided.

  In addition, as a second aspect, the proton conductive layer formed on the substrate, the catalyst layer and the second electrode layer stacked so as to be separated from the upper surface of the proton conductive layer, and the first stacked on the catalyst layer The electrode layer can be provided.

  Furthermore, as a third aspect, a first electrode layer and a second electrode layer formed so as to be separated from each other on the substrate, a catalyst layer laminated on the first electrode layer, a second electrode layer, and A proton conductive layer laminated to cover the catalyst layer can be provided.

  In the first embodiment and the second embodiment, the first electrode layer is preferably a gas permeable electrode layer, and hydrogen gas efficiently contacts the catalyst layer through the gas permeable electrode layer. Will be able to.

  In the second aspect and the third aspect, the edges of the first electrode layer, the catalyst layer, and the second electrode layer are each formed in a comb tooth shape, and the other comb tooth is formed in the gap between the one comb tooth. It is preferable that the protons are decomposed so that the protons decomposed in the catalyst layer move from the catalyst layer to the second electrode layer through the proton conductive layer, and a short and sufficient path is secured. And the sensitivity can be significantly improved.

  The proton conductive layer is preferably composed of a solid polymer electrolyte.

  It is further preferable that the proton conductive layer is made of a solid polymer electrolyte to which a carbon material is added in order to ensure output stability.

  The proton conductive layer is preferably composed of a solid ionic conductor obtained by curing a mixture of ionic liquid and resin.

  The proton conductive layer is preferably composed of an inorganic / organic hybrid electrolyte.

  The catalyst layer is preferably made of a metal or alloy having a catalytic function by contacting with hydrogen gas, or an organic metal or organic substance having catalytic activity.

  As described above, according to the present invention, it is possible to provide a hydrogen gas sensor having good hydrogen gas selectivity, easy handling, and low power consumption without performing a purge operation.

Configuration of a vertical substrate type hydrogen gas sensor according to the present invention Schematic diagram of substrate-side hydrogen gas sensor according to the present invention Configuration diagram of a counter electrode substrate type hydrogen gas sensor according to the present invention Explanatory drawing of the principal part of the hydrogen gas sensor which shows another embodiment Configuration diagram of vertical substrate hydrogen gas sensor according to Experimental Example 1 Hydrogen gas detection characteristic diagram of the hydrogen gas sensor in Experimental Example 1 Configuration diagram of counter electrode substrate type hydrogen gas sensor according to Experimental Example 2 Hydrogen gas detection characteristic diagram of the hydrogen gas sensor in Experimental Example 2 The structure of the substrate horizontal type | mold hydrogen gas sensor by Experimental example 3 is shown, (a) is a cross-sectional perspective schematic diagram, (b) is a perspective schematic diagram. Hydrogen gas detection characteristic diagram of hydrogen gas sensor according to Experimental Example 3 The structure of the substrate horizontal type hydrogen gas sensor by Experimental Example 4 is shown, (a) is a schematic cross-sectional perspective view, and (b) is a schematic perspective view. Hydrogen gas detection characteristic diagram of hydrogen gas sensor according to Experimental Example 4 The structure of the self-supporting film type hydrogen gas sensor according to Reference Experimental Example 1 is shown, (a) is a sectional view, and (b) is a schematic perspective view. Hydrogen gas detection characteristics diagram of hydrogen gas sensor according to Reference Experiment 1 Hydrogen gas detection characteristics diagram of hydrogen gas sensor according to Reference Experiment 1 The structure of the board | substrate vertical type hydrogen gas sensor by Experimental example 5 is shown, (a) is a cross-sectional perspective schematic diagram, (b) is a perspective schematic diagram. Hydrogen gas detection characteristics diagram of hydrogen gas sensor in Experimental Example 5 Hydrogen gas detection characteristics diagram of hydrogen gas sensor in Experimental Example 5 The structure of the self-supporting film type hydrogen gas sensor according to Reference Experimental Example 2 is shown, (a) is a schematic cross-sectional perspective view, and (b) is a schematic perspective view. Hydrogen gas detection characteristics diagram of hydrogen gas sensor according to Reference Experiment 2 (A) is explanatory drawing of the electrode by Experimental example 6, (b) is a block diagram of the board | substrate vertical type hydrogen gas sensor by Experimental example 6. Hydrogen gas detection characteristic diagram of hydrogen gas sensor according to Experimental Example 6 Configuration diagram of a self-supporting membrane hydrogen gas sensor

  A substrate type hydrogen gas sensor according to the present invention will be described below. As shown in FIGS. 1 to 3, the hydrogen gas sensor 1 is bonded to the proton conductive layer 2, the first electrode layer 4 a bonded via the proton conductive layer 2 and the catalyst layer 3, and the proton conductive layer 2. The second electrode layer 4 b is formed by being laminated on the substrate 10. Such a hydrogen gas sensor 1 can be configured in a plurality of modes.

  As a first aspect, as shown in FIG. 1A, a second electrode layer 4b formed on the substrate 10, a proton conductive layer 2 laminated on the second electrode layer 4b, and a proton conductive layer 2 and the first electrode layer 4a laminated on the catalyst layer 3, the substrate vertical hydrogen gas sensor 1 can be configured.

  As long as the substrate 10 can stably hold the proton conductive layer 2 formed on the upper surface of the substrate 10, from a substrate using an inorganic material such as glass, ceramic, or silicon to a flexible substrate using a resin material. A variety of materials can be used.

  Since the substrate 10 is exposed to a high temperature environment when the proton conductive layer 2 is formed, a certain heat resistance is required.

  As resin materials that constitute the substrate, polyethylene terephthalate, polyethylene naphthalate, nylon, cyclic olefin, polyethylene sulfonate, polysulfone, polyimide, polyamideimide, polycarbonate, polybutylene terephthalate, urethane, acrylic, polyethylene, polystyrene, polypropylene, fluorine Series resins (PTFE, PFA, ETFE, FEP, PVDF, etc.) can be used.

  As the proton conductive layer 2, a solid polymer electrolyte S can be adopted, and perfluorosulfonic acid-based, perfluorocarboxylic acid-based perfluoropolymer having high proton conductivity, Poly (styrene-ran- It is preferable to use a solid polymer electrolyte membrane made of partially sulfonated styrene-olefin copolymer such as ethylene), sulfonated, etc., and Nafion (registered trademark: NAFION), Aciplex (registered trademark: Asahi Kasei Corporation), etc. are preferable. Can be used for

  Furthermore, by dispersing the conductive particles in the solid polymer electrolyte S, the stability of the output can be ensured. As the conductive particles dispersed in the solid polymer electrolyte S, a conductive resin, a carbon C material, or the like can be selected.

  As such a carbon C material, any of carbon nanotubes (hereinafter also referred to as “CNT”), fullerene, graphite, nanocarbon, carbon black, nanodiamond, and nanoporous carbon can be selected. Specific examples of carbon black include furnace black, channel black, and graft carbon. In any case, excellent stability is shown.

  The size (particle diameter, length, or diameter) of carbon C (CNT, graphite, etc.) is not particularly limited, but a higher aspect ratio is preferable, and in particular, the length is 1 μm to 500 μm, and the diameter is 5 to 200 nm. Is preferred.

  Furthermore, the carbon C dispersed in the solid polymer electrolyte S is not limited to one type of carbon, and different types of carbon, such as different types of CNT, CNT and graphite, may be mixed.

  FIG. 1 (a) shows a proton conductive layer 2 in which carbon C is dispersed in a solid polymer electrolyte S. As shown in FIG. 1 (b), the proton conductive layer 2 includes carbon C It may be composed only of the solid polymer electrolyte S in which conductive particles such as are not dispersed. Compared to the latter, the former has a stable output when not in contact with hydrogen gas, and can detect hydrogen gas with high accuracy.

  When the solid polymer electrolyte S or the solid polymer electrolyte S in which carbon C is dispersed in the solid polymer electrolyte S is used, the solid polymer electrolyte solution or the solid polymer electrolyte solution in which carbon C is dispersed is used as the substrate 10. The proton conductive layer 2 can be formed by casting on the top.

  The catalyst layer 3 is configured such that a catalyst 3 a made of a metal having a catalytic function by being brought into contact with hydrogen gas is supported on the upper surface of the proton conductive layer 2.

  As the catalyst 3a, platinum Pt or a platinum alloy is suitably used. Besides, gold Au, silver Ag, iridium Ir, palladium Pd, ruthenium Ru, osmium Os, cobalt Co, nickel Ni, tungsten W, molybdenum Mo, manganese A metal containing at least one selected from Mn, yttrium Y, vanadium V, niobium Nb, titanium Ti, and a rare earth metal can be used.

Instead of the metal catalyst, a carbide such as molybdenum carbide Mo ₂ C, or an oxide such as zirconia oxide or tantalum oxide may be used.

  One kind of these catalysts 3a may be used alone, a plurality of them may be used in combination, or a part or all of them may be used in the form of an alloy.

  It is also possible to use a catalyst 3a made of an organic metal or an organic substance having catalytic activity by contacting with hydrogen gas. Examples of such organometallic catalysts include N, N'-Bis (salicylidene) ethylene-diamino-metal (= Ni, Fe, V, etc.), N, N'-mono-8-quinoly-σ-phenylenediamino-metal. (= Ni, Fe, V, etc.) can be used, and examples of organic substances include pyrrolopyrrole red pigments and dipyridyl derivatives.

  The catalyst layer 3 is formed by sputtering, vacuum deposition, electron irradiation, CVD, PVD, impregnation, spray coating, spray pyrolysis, kneading, spraying, coating with a roll or iron, screen printing, kneading method, photoelectrolysis method, coating method. It can be formed by employing a sol-gel method, a dip method or the like.

In particular, it is preferable to form the catalyst layer 3 by sputtering. The sputtering treatment time is preferably less than 90 seconds, and more preferably 60 seconds or less. The DC and RF output values during sputtering are not particularly limited, but are preferably 1.2 W / cm ² or more.

  The first electrode 4a needs to be made of a gas-permeable material so that hydrogen gas contacts the catalyst layer 3, and carbon paper, carbon fiber nonwoven fabric, or the like can be suitably used. Furthermore, it is also possible to comprise a copper-nickel alloy thin film in which a large number of pores are formed, or a metal porous sintered body having good conductivity.

  In the case of using carbon paper, carbon fiber nonwoven fabric or the like, it is preferable to apply an ion exchange resin in order to make a close connection with the proton conductive layer 2 through the catalyst layer 3. As an ion exchange resin, various Nafion (DuPont registered trademark: Nafion) manufactured by DuPont, an ion exchange resin manufactured by Dow Chemical, or the like can be used.

  The second electrode 4b does not require air permeability, and can use a metal such as copper, aluminum, stainless steel, or a carbon material, but it is desirable to select a material that does not corrode even under high humidity. Such an electrode layer can be formed on the substrate 10 by a known film forming method such as coating, screen printing, plating, sputtering, or vacuum deposition.

  Moreover, as shown in FIG.1 (c), it is also possible to comprise the board | substrate 10 (4b) made from metals, such as copper and aluminum, combining the board | substrate 10 and the 2nd electrode layer 4b.

  The hydrogen gas sensor 1 described above includes a step of forming the second electrode layer 4b on the substrate 10 by screen printing or the like, a step of forming the proton conductive layer 2 thereon, and a catalyst 3a on the proton conductive layer 2. It is manufactured by a step of forming the catalyst layer 3 by carrying it, a step of forming the first electrode layer 4a on the upper portion of the catalyst layer 3, and a step of cutting the laminate through each step into a predetermined size.

  In the step of forming the proton conductive layer 2, for example, a carbon nanotube, fullerene, graphite, nanocarbon, carbon black is added to a solid polymer electrolyte solution obtained by dissolving a solid polymer electrolyte in an alcohol solvent such as water-propanol. , A step of mixing a predetermined amount of carbon C selected from nanodiamond and nanoporous carbon, a dispersion treatment step of dispersing carbon C in the solid polymer electrolyte solution, casting on the substrate 10 after the dispersion treatment, etc. And a heating step of removing the solvent by heating and drying the molded substrate.

  Instead of the alcohol solvent, an organic solvent having polarity such as water-dimethylformamide (DMF) can be used. In any case, the dispersibility of carbon C differs depending on the combination of the solvent and the carbon material mixed in the solvent.

  In the heating and drying step, in order to heat and dry while maintaining the dispersion state of carbon C, it is important to adjust the heating time and heating temperature based on the composition of the solvent, the weight ratio of the solid polymer electrolyte and carbon, and the like. .

  If the state where carbon C is dispersed in the electrolyte membrane can be secured, the blending ratio of the solid polymer electrolyte and carbon is not particularly limited, but is preferably 100: 1 to 10:10.

  In the case where the conductive particles are not dispersed, a forming step of forming a solid polymer electrolyte solution obtained by dissolving the solid polymer electrolyte in an alcohol solvent such as water-propanol into a predetermined shape on the substrate 10 by casting or the like. Then, a film is formed through a heating and drying process in which the molded substrate is dried by heating to remove the solvent.

  As a second embodiment, as shown in FIG. 2A, the proton conductive layer 2 formed on the substrate 10, the catalyst layer 3 stacked so as to be separated from the upper surface of the proton conductive layer 2, and the second layer The substrate horizontal hydrogen gas sensor 1 can be configured by including the electrode layer 4 b and the first electrode layer 4 a laminated on the catalyst layer 3.

  In this case, the first electrode layer 4a needs to have air permeability, but the second electrode layer 4b does not need to have air permeability.

  As shown in FIG. 2B, wiring patterns 5a and 5b for extracting the output of the hydrogen gas sensor 1 are formed on the substrate 10 so that the electrode layers 4a and 4b are connected to the wiring patterns 5a and 5b, respectively. It is also possible to constitute each electrode layer 4a, 4b.

  As a 3rd aspect, as shown to Fig.3 (a), it laminates | stacks on the 1st electrode layer 4a and the 1st electrode layer 4a and the 2nd electrode layer 4b which were formed so that it might space apart on the board | substrate 10. FIG. The counter electrode substrate type hydrogen gas sensor 1 can be configured by including the catalyst layer 3 formed and the proton conductive layer 2 laminated so as to cover the second electrode layer 4 b and the catalyst layer 3.

  In this case, the first electrode layer 4a does not need to be a material having air permeability, and can be composed of the same material as the second electrode layer 4b. The hydrogen gas passes through the proton conductive layer 2 and comes into contact with the catalyst layer 3.

  Either the first electrode layer 4 a or the second electrode layer 4 b can be used also as the substrate 10. In this case, as shown in FIG. 3B, the other electrode layer 4b needs to be laminated on the substrate 10 via the insulating layer 4c.

  The composition and materials of the electrode layers 4a and 4b, the proton conductive layer 2, and the catalyst layer 3 and the manufacturing process are substantially the same for the hydrogen gas sensors of the second and third aspects.

  Further, when a gas diffusion layer made of carbon paper, carbon nonwoven fabric, or the like is provided on either the front or back surface of the electrode layer 4a, hydrogen gas can be brought into contact with the catalyst layer 3 evenly, and the sensitivity is improved. Further, by interposing a gas diffusion layer made of carbon paper, carbon non-woven fabric or the like between the electrode layer 4a and the catalyst layer 3 or between the electrode layer 4b and the proton conductive layer, the corrosion resistance of the electrode layers 4a and 4b is improved. improves.

  In the hydrogen gas sensor 1 according to the present invention, the catalyst layer 3 can also be used as the electrode layer 4a. For example, the electrode layer 4a can be configured using a catalyst metal such as platinum as a catalyst. In this case, the other electrode layer 4b is preferably a type of electrode having a work function different from that of platinum.

  In the hydrogen gas sensor 1 according to the present invention, since the proton conductive layer 2 is cast on the mold and dried, and does not require complicated processes such as a process of peeling from the mold, the manufacturing process can be simplified. In addition to being able to do so, it is possible to manufacture a small-sized hydrogen gas sensor that secures shape retention and is thinned.

  In the hydrogen gas sensor 1 of the first and second embodiments, when hydrogen gas flows into the electrode 4a on the catalyst layer 3 side, the hydrogen is decomposed into hydrogen ions and electrons by the action of the catalyst, and the electrode 4a where the electrons stay is the electrode. Negative potential with respect to 4b. Further, in the hydrogen gas sensor 1 of the third aspect, when hydrogen gas flows into the catalyst layer 3 through the proton conductive layer 2, the electrode 4a in which the hydrogen is decomposed into hydrogen ions and electrons by the action of the catalyst and the electrons stay is provided. Negative potential with respect to 4b. That is, the electrode 4a on the side where the catalyst layer 3 is formed becomes a negative electrode. At this time, the hydrogen gas concentration can be detected by detecting a voltage value having a correlation with the hydrogen gas concentration by an external circuit.

  Hydrogen gas detection ability can be improved by shortening the path | route of the proton conductive layer 2 used as the conductive path | route of the proton which moves from the catalyst layer 3 to the 2nd electrode layer 4b. Therefore, as shown in FIG. 4, in the hydrogen gas sensor 1 of the second aspect and the third aspect, the edges of the first electrode layer 4a, the catalyst layer 3, and the second electrode layer 4b are comb-like. It is preferable that the layers are laminated so that the other comb tooth is positioned in the gap between the one comb teeth.

  In each of the hydrogen gas sensors 1 described above, the solid polymer electrolyte is used as the proton conductive layer 2. However, as the proton conductive layer 2, a solid ionic conductor obtained by curing a mixture of an ionic liquid and a resin is used. Is also possible.

  The solid ionic conductor is obtained by mixing an ionic liquid with any one of a photo-curing resin, a thermosetting resin, and a thermoplastic resin, followed by curing treatment.

  As the ionic liquid, a cation moiety selected from one or more of imidazolium ions, pyridinium ions, aliphatic amine ions, alicyclic amine ions, and aliphatic phosphonium ions, a halogen ion, a halogen ion, One having one or more types of anion sites selected from any of system ions, phosphonate ions, borate ions and triflate ions can be suitably selected.

  As the photocurable resin, epoxy acrylate, urethane acrylate, polyester acrylate, unsaturated polyester resin, diazo resin, azide resin, or the like can be used. Here, the photocurable resin means a broad concept including an ultraviolet curable resin, a visible light curable resin, and an electron beam curable resin.

  As the thermosetting resin, the ionic liquid, the thermosetting resin, and the reactant are stirred and mixed, and then formed into a film shape and subjected to heat treatment, whereby the film-shaped solid ionic conductor 1 is obtained. As the thermosetting resin, phenol resin, epoxy resin, urea resin, melamine resin, unsaturated polyester resin, polyurethane, polyimide, urea resin, furan resin, silicone resin, allyl resin, or the like can be used.

  As the thermoplastic resin, the ionic liquid and the thermoplastic resin in a molten state at a high temperature are stirred and mixed, and then molded into a film shape and cooled to obtain the film-shaped solid ionic conductor 1. In addition to general-purpose resins such as polyethylene, polypropylene, polystyrene, and polyethylene terephthalate, engineering plastics such as polycarbonate, polyamide, and polyimide, and super engineering plastics can be used as the thermoplastic resin.

  The proton conductive layer 2 using a solid ionic conductor comprises a mixing step of mixing and stirring an ionic liquid in a resin selected from a photo-curing resin, a thermosetting resin, or a thermoplastic resin, and the mixing step. A film is formed by a step of dropping and casting the ion conductor subjected to the stirring and mixing treatment onto the substrate 10 and a hardening treatment step of hardening the cast ion conductor.

  Furthermore, an organic-inorganic hybrid electrolyte can be employed as the proton conductive layer 2. As the organic-inorganic hybrid electrolyte, a material obtained by nano-dispersing an organic electrolyte or a polymer electrolyte in a ceramic such as silica, titania, zirconia, or alumina by a sol-gel method or the like can be used. In particular, a urea-based silica hybrid electrolyte produced from urea and silica alkoxide by a sol-gel method is suitable, but other organic-inorganic hybrid electrolytes can also be used.

  The hydrogen gas sensor described above can selectively detect hydrogen gas not only in the atmosphere but also in an environment where oxygen is not present.

Examples will be described below.
[Experimental Example 1]
<Formation of platinum counter electrode substrate>
A polyimide film (thickness 30 μm, manufactured by Toray DuPont) with platinum as an electrode formed on the upper surface by sputtering was cut into a strip of 1 mm width, and two strip-shaped polyimide films were cut into white PET (Toray mirror U2 with a thickness of 188 μm). ) Affixed and fixed on the film substrate with an adhesive material at intervals of 0.5 mm.

<Formation of catalyst layer>
One platinum electrode itself is also used as the catalyst layer, and carbon paste (FTU-30 manufactured by Asahi Chemical Research Laboratories) is applied on the other platinum electrode by diluting with a special solvent. A carbon electrode was formed by drying for a period of time.

<Formation of electrolyte membrane>
A sulfonated styrene ethylene copolymer film was formed as a solid polymer electrolyte. 1 μL of sulfonated styrene ethylene copolymer solution (Aldrich Poly (styrene-ran-ethylene), sulfonated, 5 wt% solution in 1-propanol) is dropped on the center of the counter electrode substrate so that the membrane covers the two electrodes. And dried in a hot air circulating oven at 80 ° C. for 1 hour to form a film. As a result, a counter electrode substrate type hydrogen gas sensor shown in FIG. 5 was obtained.

<Evaluation of hydrogen gas responsiveness>
The potential difference between the platinum electrode and the carbon electrode on the sensor substrate was measured with a digital multimeter (VOAC7411 manufactured by Iwatatsu). The sensor surface was irradiated with 4000 ppm concentration (air-based) hydrogen gas at a flow rate of 10 L / min for 30 seconds and stopped for 30 seconds alternately, and the change in voltage due to contact with hydrogen gas was measured.

  Next, instead of hydrogen gas of 1% concentration (air base), irradiation and stop for 30 seconds were repeated in the same manner, and the voltage was measured. Further, the voltage was measured by repeating the irradiation and stopping of nitrogen gas at the same flow rate for 30 seconds.

  As shown in FIG. 6, the output voltage of the sensor increases when it comes into contact with hydrogen gas and decreases when the hydrogen gas stops. The sensor output voltage increases as the hydrogen gas concentration increases. The output voltage of the sensor does not change by contact with nitrogen gas, and can be determined as a reaction due to hydrogen.

[Experimental example 2]
<Formation of silver counter electrode substrate>
A silver paste (LS-415-M, manufactured by Asahi Chemical Research Laboratories) is screen printed at 1 mm width and 0.5 mm intervals on a white PET (Toray mirror U2) film substrate with a thickness of 188 μm to form a silver counter electrode substrate. Created.

<Formation of catalyst layer>
On one silver electrode, an opening having a width of 1 mm and a length of 5 mm was provided and masked, and then a platinum thin film was formed by RF sputtering for 30 seconds in an argon gas at a power of 300 W using a platinum target. . On the other silver electrode, an opening with a width of 1 mm and a length of 5 mm is provided for masking, and then carbon paste (FTU-30 manufactured by Asahi Chemical Research Laboratories) is diluted with a special solvent and applied. A carbon electrode was formed by drying at 100 ° C. for 1 hour.

<Formation of electrolyte membrane>
A sulfonated styrene ethylene copolymer film was formed as a solid polymer electrolyte. 10 μL of sulfonated styrene ethylene copolymer solution (Aldrich Poly (styrene-ran-ethylene), sulfonated, 5 wt% solution in 1-propanol) is dropped on the center of the counter electrode substrate so that the membrane covers the two electrodes. And dried in a hot air circulating oven at 80 ° C. for 1 hour to form a film. As a result, a counter electrode substrate type hydrogen gas sensor shown in FIG. 7 was obtained.

<Evaluation of hydrogen gas responsiveness>
The potential difference between the platinum electrode and the carbon electrode of the fabricated sensor substrate was measured with a digital multimeter (VOAC7411 manufactured by Iwatatsu). The sensor surface was irradiated with 4000 ppm concentration (air-based) hydrogen gas at a flow rate of 10 L / min for 30 seconds and stopped for 30 seconds alternately, and the change in voltage due to contact with hydrogen gas was measured.

  Next, instead of hydrogen gas of 1% concentration (air base), irradiation and stop for 30 seconds were repeated, and the voltage was measured. Further, the voltage was measured by repeating the irradiation and stopping of nitrogen gas at the same flow rate for 30 seconds.

  As shown in FIG. 8, it was confirmed that the signal voltage of the sensor increased due to hydrogen gas contact and the signal voltage decreased due to hydrogen gas stoppage.

[Experimental Example 3]
<Formation of electrolyte membrane>
A film of sulfonated styrene ethylene copolymer was formed as a solid polymer electrolyte on a 188 μm thick PET film. Under the inner 20 × 50 mm mold frame, a PET film is laid and 4 ml of sulfonated styrene-ethylene copolymer solution (Aldrich Poly (styrene-ran-ethylene), sulfonated, 5 wt% solution in 1-propanol) is placed. Poured and dried in a hot air circulating oven at 80 ° C. for 4 hours to form an electrolyte membrane.

<Formation of catalyst layer>
A platinum thin film was formed on the upper half of the electrolyte membrane by RF sputtering using a platinum target in an argon gas at a power of 300 W for 30 seconds. A masking tape was applied on the electrolyte membrane, and an opening having a width of 19 mm and a length of 25 mm was provided.

<Formation of measurement electrode>
Carbon paper was laid on the platinum surface of the electrolyte membrane and sandwiched between the aluminum electrode plates with the carbon membrane from above and below, and carbon paper was laid on the other electrolyte membrane and sandwiched between the aluminum electrode plates with the carbon membrane from above and below. The exposed length of the platinum film is 3 mm, and the distance between the platinum film and the electrode is 4 mm. In this way, a horizontal substrate type hydrogen gas sensor shown in FIGS. 9A and 9B was obtained.

<Evaluation of hydrogen gas responsiveness>
The potential difference between the platinum electrode and the carbon electrode on the sensor substrate was measured with a digital multimeter (VOAC7411 made by Iwatatsu). The sensor surface was irradiated with 4000 ppm concentration (air-based) hydrogen gas at a flow rate of 10 L / min for 30 seconds and stopped for 30 seconds alternately, and the change in voltage due to contact with hydrogen gas was measured.

  As a result, as shown in FIG. 10, it was confirmed that the sensor signal voltage increased due to hydrogen gas contact and the signal voltage decreased due to hydrogen gas stoppage.

[Experimental Example 4]
<Formation of electrolyte membrane>
A urea-based silica hybrid film was formed as a solid electrolyte on a 188 μm thick PET film.
<Preparation of urea silica hybrid sol solution>
TMSU (1-3- (Trimethoxysilyl) propyl) urea) 0.75M / L, HTFSI (Bis (trifluoromethanesulfonyl) imide) 0.25M / L, urea 0.25M / L, water 4M / L and hydrochloric acid 0.01M / 30 g of a methanol solution of L was prepared and stirred with a stirrer for 3 hours.

<Cast film formation>
A silicone rubber sheet having a thickness of 1 mm was laid under the inner 20 × 50 mm mold frame, and 10 ml of urea silica hybrid sol solution was poured into the mold frame. It was dried in a 60 ° C. vacuum oven overnight and then dried in a hot air circulating oven at 80 ° C. for 1 hour. A urea silica hybrid membrane having a thickness of 300 μm was obtained.

<Formation of catalyst layer>
A platinum thin film was formed on the upper half of the electrolyte membrane by RF sputtering using a platinum target in an argon gas at a power of 300 W for 30 seconds. A masking tape was applied on the electrolyte membrane, and an opening having a width of 19 mm and a length of 25 mm was provided.

<Formation of measurement electrode>
Carbon paper was laid on the platinum surface of the electrolyte membrane, and sandwiched from above and below by an aluminum electrode with a carbon membrane. Carbon paper was laid on the other electrolyte membrane and sandwiched from above and below by an aluminum electrode plate with a carbon membrane. The carbon film was prepared by diluting a carbon paste (FTU-30 manufactured by Asahi Chemical Research Laboratories) with a special solvent, applying it to an aluminum plate, and drying it. The exposed length of the platinum film is 3 mm, and the distance between the platinum film and the electrode is 1 mm. As a result, a horizontal substrate type hydrogen gas sensor shown in FIG. 11 was obtained.

<Evaluation of hydrogen gas responsiveness>
The potential difference between the platinum electrode and the carbon electrode of the obtained sensor substrate was measured with a digital multimeter (VOAC7411 made by Iwatatsu). The sensor surface was irradiated with 4000 ppm concentration (air-based) hydrogen gas at a flow rate of 10 L / min for 30 seconds and stopped for 30 seconds alternately, and the change in voltage due to contact with hydrogen gas was measured.

  As shown in FIG. 12, it was confirmed that the sensor signal voltage increased due to hydrogen gas contact and the signal voltage decreased due to hydrogen gas stoppage.

[Reference Experimental Example 1]
<Formation of electrolyte membrane>
As a reference example of Experimental Example 4, a self-supporting membrane of urea-based silica hybrid membrane was formed as a solid polymer electrolyte membrane.
<Preparation of urea silica hybrid sol solution>
TMSU (1-3- (Trimethoxysilyl) propyl) urea) 0.75M / L, HTFSI (Bis (trifluoromethanesulfonyl) imide) 0.25M / L, urea 0.25M / L, water 4M / L and hydrochloric acid 0.01M / 30 g of a methanol solution of L was prepared and stirred with a stirrer for 3 hours.

<Cast film formation>
A Teflon sheet (DuPont registered trademark: Teflon) was laid under the inner 50 × 50 mm mold frame, 8 ml of urea silica hybrid sol solution was poured in, and allowed to stand overnight at room temperature to dry. It was dried in a 60 ° C. vacuum oven overnight and then dried in a hot air circulating oven at 80 ° C. for 1 hour. The dried membrane was peeled from the mold to obtain a urea silica hybrid free-standing membrane having a thickness of 100 μm.

<Formation of catalyst layer>
A platinum thin film was formed on one side of the self-supporting membrane of the electrolyte membrane by RF sputtering for 30 seconds in an argon gas with a power of 300 W using a platinum target.
<Element assembly>
The self-supporting membrane of the electrolyte membrane was cut into a φ13 mm round shape, and both sides were sandwiched with carbon paper cut into a φ12 round shape. A φ20 SUS electrode plate with a φ6 mm hole in the center was sandwiched on both sides to serve as an electrode for output extraction (in this case, the platinum film surface side was the negative electrode and the opposite side was the positive electrode). As a result, a self-supporting film type hydrogen gas sensor as shown in FIG. 13 was obtained.

<Evaluation of hydrogen gas responsiveness>
The potential difference between the platinum side electrode substrate and the counter electrode substrate of the obtained sensor element was measured with a digital multimeter (VOAC7411 manufactured by Iwatatsu Corporation). The sensor surface was irradiated with hydrogen gas and nitrogen gas of 4000 ppm and 4% concentration (air base) at a flow rate of 0.5 L / min for 30 seconds and stopped for 30 seconds alternately, and the voltage change due to contact with hydrogen gas was measured. .

  As shown in FIGS. 14 and 15, it was confirmed that the sensor signal voltage increased due to hydrogen gas contact and the signal voltage decreased due to hydrogen gas stoppage.

  12 and 15 show the output characteristics for 4000 ppm concentration (air-based) hydrogen gas. Although the sensitivity is different, it was found that both can detect hydrogen gas.

[Experimental Example 5]
<Formation of electrolyte membrane>
On the aluminum electrode plate, a CNT-containing sulfonated styrene ethylene copolymer film was formed as a solid polymer electrolyte. A sulfonated styrene ethylene copolymer solution (poly (styrene-ran-ethylene), sulfonated, 5 wt% solution in 1-propanol manufactured by Aldrich) was volatilized with an evaporator, and the solvent was replaced with DMF (dimethylformamide). 0.08 g of CNT was mixed with 8 ml of a sulfonated styrene ethylene copolymer solution (DMF solvent, solid content 5 wt%), and stirred for 10 minutes with an ultrasonic homogenizer.

  Thereafter, the mixture was stirred for 1 hour with a stirrer to prepare a CNT-containing sulfonated styrene ethylene copolymer solution. An aluminum plate (thickness 1 mm) is laid under an inner 50 × 50 mm mold frame, 8 ml of the above solution is poured, dried in a hot air circulating oven at 110 ° C. for 4 hours, and a carbon-dispersed solid polymer electrolyte having a thickness of 100 μm. A film was formed.

<Formation of catalyst layer>
A platinum thin film was formed on one surface of the electrolyte membrane by RF sputtering using a platinum target in an argon gas at a power of 300 W for 30 seconds.

<Element assembly>
An aluminum plate with an electrolyte membrane was cut into a square shape of 10 mm, and both sides were sandwiched with carbon paper cut into a round shape of φ12. A SUS electrode plate of φ20 with a φ6 mm hole in the center was sandwiched between the sides to form an output output electrode (in this case, the platinum film surface side was the negative electrode and the opposite side was the positive electrode). As a result, a vertical substrate type hydrogen gas sensor shown in FIG. 16 was obtained.

<Evaluation of hydrogen gas responsiveness>
The potential difference between the platinum side electrode substrate and the counter electrode substrate of the obtained sensor element was measured with a digital multimeter (VOAC7411 manufactured by Iwatatsu Corporation). The sensor surface is irradiated with hydrogen gas and nitrogen gas of 4000 ppm and 4% concentration (air base) at a flow rate of 0.5 L / min for 30 seconds, stopped for 30 seconds, and repeatedly irradiated for 30 seconds to change the voltage due to contact with hydrogen gas. It was measured.

  As shown in FIGS. 17 and 18, it was confirmed that the sensor signal voltage increased due to hydrogen gas contact and the signal voltage decreased due to hydrogen gas stoppage.

[Reference Experiment Example 2]
<Formation of electrolyte membrane>
As a reference example of Experimental Example 5, a self-supporting film of a sulfonated styrene-ethylene copolymer containing carbon nanotubes (hereinafter referred to as “CNT”) was formed as a solid polymer electrolyte. A sulfonated styrene ethylene copolymer solution (poly (styrene-ran-ethylene), sulfonated, 5 wt% solution in 1-propanol manufactured by Aldrich) was volatilized with an evaporator, and the solvent was replaced with DMF (dimethylformamide). 0.08 g of CNT was mixed with 8 ml of a sulfonated styrene ethylene copolymer solution (DMF solvent, solid content 5 wt%), and stirred for 10 minutes with an ultrasonic homogenizer. Thereafter, the mixture was stirred for 1 hour with a stirrer to prepare a CNT-containing sulfonated styrene ethylene copolymer solution.

  Place a Teflon sheet (DuPont registered trademark: Teflon) under the inner 50 × 50 mm mold frame, pour 8 ml of the above solution, dry it at 110 ° C. for 4 hours in a hot air circulating oven, and peel off from the mold Thus, a self-supporting membrane having a thickness of 100 μm was obtained.

<Formation of catalyst layer>
A platinum thin film was formed on one side of the self-supporting membrane of the electrolyte membrane by RF sputtering for 30 seconds in an argon gas with a power of 300 W using a platinum target.

<Element assembly>
The self-supporting membrane of the electrolyte membrane was cut into a φ13 mm round shape, and both sides were sandwiched with carbon paper cut into a φ12 round shape. A SUS electrode plate of φ20 with a φ6 mm hole in the center was sandwiched on both sides to form an output output electrode (in this case, the platinum film surface side was the negative electrode and the opposite side was the positive electrode). As a result, the self-supporting film type hydrogen gas sensor shown in FIG. 19 was obtained.

<Evaluation of hydrogen gas responsiveness>
The potential difference between the platinum side electrode substrate and the counter electrode substrate of the obtained sensor element was measured with a digital multimeter (VOAC7411 manufactured by Iwatatsu Corporation). The sensor surface was irradiated with hydrogen gas at a concentration of 4000 ppm (air base) at a flow rate of 0.5 L / min for 30 seconds and stopped for 30 seconds alternately, and the change in voltage due to contact with hydrogen gas was measured.

  As shown in FIG. 20, it was confirmed that the sensor signal voltage increased due to hydrogen gas contact and the signal voltage decreased due to hydrogen gas stoppage.

  18 and 20 show output characteristics with respect to hydrogen gas having a concentration of 4000 ppm (air base). Although the sensitivity is different, it was found that both can detect hydrogen gas.

[Experimental Example 6]
<Formation of comb-teeth silver counter electrode substrate>
As shown in FIG. 21 (a), a silver paste (LS-415-M, manufactured by Asahi Chemical Research Laboratories) is placed on a white PET (Toray mirror U2) film substrate having a thickness of 188 μm at a 1 mm width and 0.5 mm intervals. A comb-like silver counter electrode substrate was prepared by screen printing with a comb-like pattern for each book.

<Formation of catalyst layer>
On one silver electrode, an opening corresponding to the shape of the comb teeth is provided for masking, and then a platinum thin film is formed by RF sputtering for 30 seconds in an argon gas at a power of 300 W using a platinum target. did.
On the other silver electrode, an opening matching the shape of the comb teeth is provided for masking, and then carbon paste (FTU-30 manufactured by Asahi Chemical Research Laboratories) is diluted with a special solvent and applied. A carbon electrode was formed by drying at 100 ° C. for 1 hour.

<Formation of electrolyte membrane>
Ultraviolet curable resin (3Bond 3130B) and ionic liquid (Daiichi Kogyo Seiyaku IL110) are mixed at a weight ratio of 1: 1, applied to the electrode substrate to a thickness of about 2 mm, and cured by UV irradiation for 60 seconds. To form a film. As a result, a counter electrode substrate type hydrogen gas sensor shown in FIG. 21B was obtained.

<Evaluation of hydrogen gas responsiveness>
The potential difference between the platinum electrode and the carbon electrode of the fabricated sensor substrate was measured with a digital multimeter (VOAC7411 manufactured by Iwatatsu).
The sensor surface was irradiated with hydrogen gas at a concentration of 4% (air base) at a flow rate of 0.5 L / min for 30 seconds and stopped alternately for 30 seconds, and the change in voltage due to contact with hydrogen gas was measured.

  As shown in FIG. 22, it was confirmed that the sensor signal voltage increased due to hydrogen gas contact and the signal voltage decreased due to hydrogen gas stoppage.

  Furthermore, the same experiment was performed on methane gas and carbon monoxide gas as the gas to be detected using each of the hydrogen gas sensors described above, but no change in output appeared. From this, it was confirmed that the gas selectivity was also provided.

  The hydrogen gas sensor according to the present invention is extremely useful for a fuel cell system using hydrogen gas as an energy source, and detects the hydrogen gas concentration in the absence of oxygen gas, such as detection of hydrogen concentration in a hydrogen gas tank or a hydrogen gas supply pipe or detection of leakage. It can be suitably used when it is necessary to detect.

  Moreover, it can be suitably used for hydrogen concentration monitoring and hydrogen gas leak detection in a heat treatment apparatus of a semiconductor manufacturing plant. For example, it can be used for monitoring the hydrogen gas concentration in a heat treatment process for interfacial treatment using hydrogen gas or a mixed gas of hydrogen gas and nitrogen gas.

1: Hydrogen gas sensor 2: Proton conductive layer 3: Catalyst layer 3a: Catalysts 4, 4a, 4b: Electrode 6: Measuring instrument (voltage detection circuit)
10: Substrate C: Carbon S: Solid polymer electrolyte

Claims (11)

  A hydrogen gas sensor in which a proton conductive layer, a first electrode layer joined via a proton conductive layer and a catalyst layer, and a second electrode layer joined to the proton conductive layer are laminated on a substrate.   A second electrode layer formed on the substrate; a proton conductive layer laminated on the second electrode layer; a catalyst layer laminated on the proton conductive layer; and a first electrode layer laminated on the catalyst layer. The hydrogen gas sensor according to claim 1 provided.   A proton conductive layer formed on the substrate, a catalyst layer and a second electrode layer stacked so as to be separated from the upper surface of the proton conductive layer, and a first electrode layer stacked on the catalyst layer. Item 2. The hydrogen gas sensor according to Item 1.   The first electrode layer and the second electrode layer formed on the substrate so as to be separated from each other, the catalyst layer laminated on the first electrode layer, and the second electrode layer and the catalyst layer are laminated. The hydrogen gas sensor according to claim 1, further comprising a proton conductive layer.   The hydrogen gas sensor according to claim 2 or 3, wherein the first electrode layer is a gas permeable electrode layer.   The first electrode layer, the catalyst layer, and the edge of the second electrode layer are each formed in a comb-like shape, and are laminated so that the other comb-teeth is positioned in the gap between the one comb-teeth. Or the hydrogen gas sensor of 4.   The hydrogen gas sensor according to claim 1, wherein the proton conductive layer is made of a solid polymer electrolyte.   The hydrogen gas sensor according to any one of claims 1 to 6, wherein the proton conductive layer is made of a solid polymer electrolyte to which a carbon material is added.   The hydrogen gas sensor according to claim 1, wherein the proton conductive layer is composed of a solid ionic conductor obtained by curing a mixture of an ionic liquid and a resin.   The hydrogen gas sensor according to any one of claims 1 to 6, wherein the proton conductive layer is made of an inorganic / organic hybrid electrolyte.   The hydrogen gas sensor according to any one of claims 1 to 10, wherein the catalyst layer is made of a metal or alloy having a catalytic function by contacting with hydrogen gas, or an organic metal or organic substance having catalytic activity.

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