Hydrogen Gas Concentration Sensor

Abstract

To provide a hydrogen gas concentration sensor that has a new configuration and can detect concentration of hydrogen gas present in gas or liquid.MEANS FOR SOLVING THE PROBLEM: A hydrogen gas concentration sensor comprises a first electrode piece, a second electrode piece, an electrolyte in which the electrode pieces are disposed apart from each other, and a container which houses the first electrode piece, the second electrode piece, and the electrolyte. The first electrode piece contains a first electrode material indicating a standard electromotive force value of 0.8 V or more in a cell having the configuration of H2(-)|50 mol / m3H2SO4| a substance sample (+). The second electrode contains a second electrode material indicating a standard electromotive force value of less than 0.8 V in a cell having the same configuration. The first electrode piece penetrates through the electrolyte and has an end that is exposed to the outside of the container, and a void space is formed between the first electrode piece and the container end.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a hydrogen gas concentration sensor. [Background technology]

[0002] In the future society that utilizes hydrogen energy, it is desirable to construct a hydrogen energy utilization system that eliminates the risk of hydrogen explosions, is highly safe, and is highly convenient. The specifications of the hydrogen gas sensor must be able to instantly detect the amount of hydrogen that has leaked into the atmosphere with high accuracy, have an extremely simple structure, and be highly reliable.

[0003] On the other hand, there is a demand for the development of hydrogen concentration sensors for controlling hydrogen fuel cells in automobiles and heavy machinery (efficient use of hydrogen gas), hydrogen concentration sensors for liquids such as lubricating oil for generator bearings and transformer oil (detecting the amount of hydrogen gas dissolved and the amount of hydrogen gas due to oil deterioration), hydrogen concentration sensors in medical fluids such as those used for kidney dialysis (dissolving hydrogen to promote therapeutic effects), hydrogen concentration sensors in solutions such as hydrogen water, and hydrogen concentration sensors for process control in the chemical industry, etc.

[0004] Conventional hydrogen gas concentration sensors are based on detection methods such as semiconductor type, ionization type, and combustion type. The measurement principle of these sensors is the "extensive physical quantity" of "carrier concentration (semiconductor type)" and "ion concentration". "ionization type" or "reaction heat (combustion type or by burning and measuring the water vapor pressure) The amount of hydrogen is detected by an indirect detection method called "hydrogen sensor" and converted into an electrical quantity. The idea was as follows.

[0005] Therefore, it cannot be applied to hydrogen concentration detection in high temperature and high humidity environments, or to liquids such as oil and chemical solutions, and naturally cannot be applied to detection of the concentration of hydrogen gas dissolved in these liquids.

[0006] As an example of a hydrogen gas concentration sensor that shortens the detection time, a hydrogen gas sensor has been proposed that includes a first electrode and a second electrode made of materials with different chemical potentials relative to hydrogen, and an electrolyte in contact with these electrodes, and detects hydrogen gas based on the electromotive force value generated between these electrodes (Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 4035848 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the hydrogen gas sensor described in Patent Document 1, the first electrode, the second electrode, and the electrolyte are covered with an outer skin, so that in order to use the hydrogen gas sensor to measure the concentration of dissolved hydrogen gas in a liquid, at least the first electrode, which is the detection electrode, needs to be exposed from the outer skin and immersed in the liquid, while the electrolyte needs to be sealed from the liquid. Therefore, the structure of the hydrogen gas sensor is complicated, and the sealing method poses technical and economical problems.

[0009] The present invention aims to provide a hydrogen gas concentration sensor with a novel configuration that is capable of detecting the concentration of hydrogen gas present in environments such as high temperature and high humidity environments, and in special gases and liquids in the chemical industry. [Means for solving the problem]

[0010] The present invention is as follows. (1) A battery comprising: a first electrode piece and a second electrode piece; an electrolyte in which the electrode pieces are disposed apart from each other; and a container that contains the first electrode piece, the second electrode piece, and the electrolyte; The first electrode piece is H2(-)|50mol / m 3The cell includes a first electrode material having a standard electromotive force value of 0.8 V or more, the standard electromotive force value being 0.8 V or more. The second electrode includes a second electrode material that exhibits a standard electromotive force value of less than 0.8 V in a cell having the same configuration; the first electrode piece penetrates the electrolyte, and an electrode end of the first electrode piece is exposed to the outside from a container end of the container; A hydrogen gas concentration sensor, comprising: a gap formed between the first electrode piece and the end of the container. (2) A hydrogen gas concentration sensor as described in (1), characterized in that hydrogen gas diffuses into the container through the gap, thereby forming a three-phase interface of hydrogen gas / electrolyte / first electrode piece. (3) A hydrogen gas concentration sensor as described in (1) or (2), characterized in that the size of the gap is such that when the opposite side of the container to the container end is opened to atmospheric pressure, and when the inside of the container on the opposite side of the container is at atmospheric pressure and the hydrogen concentration is 85 vol%, the equilibrium hydrogen gas concentration of hydrogen gas that diffuses through the gap and leaks outside the container is 0.01 vol% or more and 10 vol% or less. (4) The hydrogen gas sensor according to (3), wherein the gap is formed by pores of a porous material that blocks the end of the container. (5) The hydrogen gas concentration sensor according to any one of (1) to (4), wherein the first electrode material includes at least one of platinum, a platinum alloy, and a material containing these. (6) A hydrogen gas concentration sensor described in any one of (1) to (5), characterized in that the second electrode material includes at least one of tungsten, tungsten alloy, nickel, nickel alloy, titanium, titanium alloy, copper, copper alloy, iron, iron alloy, aluminum, aluminum alloy, and materials containing these. (7) The hydrogen gas concentration sensor according to any one of (1) to (6), further comprising a third electrode piece housed in the container and disposed in the electrolyte. Effect of the Invention

[0011] According to the present invention, it is possible to provide a hydrogen gas concentration sensor of a novel configuration that can be used as a hydrogen concentration sensor for controlling hydrogen fuel cells, and that can detect the hydrogen gas concentration present in special gases and liquids in high temperature and high humidity environments such as those used in the chemical industry. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram of a hydrogen gas concentration sensor according to an embodiment. [Diagram 2] 4 is a graph showing EMF values ​​when a platinum wire is used as a first electrode piece of a hydrogen gas concentration sensor in an example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] FIG. 1 is a schematic diagram of a hydrogen gas concentration sensor according to the present embodiment.

[0014] As shown in FIG. 1, the hydrogen gas concentration sensor 10 of this embodiment includes a linear first electrode piece 11, a linear second electrode piece 12, an electrolyte 14 in which the electrodes are arranged at a distance from each other, and a container 15 having an opening 15A formed at one end (container end) for accommodating the first electrode piece 11, the second electrode piece 12, and the electrolyte 14. The end of the first electrode piece 11, i.e., the electrode end 11A, is exposed to the outside from the opening 15A. A gap H is formed between the first electrode piece 11 and the opening 15A, which is the end of the container. Here, the exposed length of the first electrode end 11A is as short as possible, and may be, for example, about several μm to several tens of μm, and a porous material that allows hydrogen gas to pass through may be disposed at the first electrode end 11A.

[0015] Therefore, when the tip of the container 15, i.e., the hydrogen gas concentration sensor 10, specifically the opening 15A, is inserted into the system to be measured, i.e., the hydrogen gas-containing medium, the hydrogen gas to be measured and other gases depending on the environment are diffused into the container 15. As a result, a three-phase interface of hydrogen gas / electrolyte / first electrode piece is formed in the container 15.

[0016] The first electrode piece 11 functions as a detection electrode for hydrogen gas, and the chemical potential of (atomic) hydrogen changes significantly when it comes into contact with hydrogen gas. The second electrode piece 12 functions as a reference electrode for hydrogen gas, and the chemical potential of the second electrode piece 12 changes very little or only slightly when it comes into contact with hydrogen gas.

[0017] The first electrode piece 11 can be made of a first electrode material having a relatively high chemical potential, specifically, H2(-)|50 mol / m 3 The first electrode material includes a cell having a standard electromotive force value of 0.8 V or more when composed of H2SO4|substance sample (+).

[0018] The above-mentioned materials include platinum, platinum alloys, and other materials that have a relatively high adsorption activity for hydrogen gas. The first electrode piece 11 can be made of these materials themselves, or these materials can be supported on a predetermined substrate. However, as long as it functions as a detection electrode for hydrogen gas without departing from the scope of the present invention, it can be used in any form.

[0019] When the first electrode piece 11 is made of a platinum-based material, hydrogen molecules are dissociated, and the hydrogen gas adsorbed on the first electrode piece 11 is quickly released, making it suitable as a detection electrode for a fast-responding hydrogen gas concentration sensor, such as a control sensor for a fuel cell or a hydrogen gas concentration sensor for hydrogen gas dissolved in a medical liquid.

[0020] The second electrode piece 12 can be made of a material with a relatively low chemical potential. Specifically, H2(-)|50 mol / m 3 The second electrode material contains H2SO4|, and the standard electromotive force value of the cell constructed with the substance sample (+) is less than 0.8 V.

[0021] The above-mentioned materials include tungsten, tungsten alloys, nickel, nickel alloys, titanium, titanium alloys, copper, copper alloys, iron, iron alloys, aluminum, aluminum alloys, and organic conductive materials, which are relatively low in hydrogen gas adsorption activity. The second electrode piece 12 can be made of these materials themselves, or these materials can be supported on a predetermined substrate. However, as long as it functions as a reference electrode for hydrogen gas without departing from the scope of the present invention, it can be used in any manner.

[0022] The electrolyte 14 can be made of an electrolyte such as phosphotungstic acid that has excellent adhesion to the first electrode 21 and the second electrode 22. The electrolyte 14 can contain a structural reinforcing material such as glass wool in addition to an electrolyte material such as phosphotungsten. In this case, the strength of the electrolyte 14 can be increased, and the adhesion to the first electrode piece 11 and the second electrode piece 12 can be further increased.

[0023] In order to ensure insulation between the first electrode piece 11 and the second electrode piece 12, the container 15 is preferably made of glass, resin, ceramics, or the like.

[0024] When the container 15 is made of an electrically conductive material such as metal, it is preferable to insulate the first electrode piece 11 from the container 15 by coating it with resin or ceramic.

[0025] The hydrogen gas concentration sensor 10 of this embodiment includes a first electrode piece 11, a second electrode piece 12, an electrolyte 14 between which the electrodes are spaced apart, and a container 15 that contains the first electrode piece 11, the second electrode piece 12, and the electrolyte 14. The first electrode piece 11 has a concentration of H2(-)|50 mol / m 3The first electrode material has a standard electromotive force value of 0.8 V or more when the cell is composed of H2SO4|substance sample (+). The second electrode piece 12 has a standard electromotive force value of less than 0.8 V when the cell is composed of the same, and the first electrode piece 11 penetrates the electrolyte 14 and has an end exposed to the outside from the container 15. In addition, hydrogen gas from the hydrogen gas-containing medium to be measured diffuses into the container 15, and a three-phase interface of hydrogen gas / electrolyte / first electrode piece is formed in the container 15. As described above, the exposed length of the first electrode end 11A may be as short as possible, for example, on the order of microns, and a porous material that allows hydrogen gas to pass through may be disposed on the first electrode end 11A.

[0026] Therefore, the hydrogen gas concentration in the hydrogen gas-containing medium can be detected by measuring the electromotive force difference between the first electrode piece 11 and the second electrode piece 12 in the container 15. In other words, by simply inserting the opening 15A of the container 15 into the hydrogen gas-containing medium, the hydrogen gas in the medium and other gases depending on the environment diffuse into the container 15, and the concentration of the hydrogen gas can be measured.

[0027] Note that the opening 15A is not sealed by the first electrode piece 11, but rather, a gap H needs to be formed between the opening 15A and the first electrode piece 11 as described above. The size of the gap H is not particularly limited, but for example, when the opposite side 15B of the container 15 to the opening 15A, which is the container end, is opened to atmospheric pressure, and when the inside of the opposite side 15B of the container 15 is at atmospheric pressure and the hydrogen concentration is 85 vol%, it is preferable that the equilibrium hydrogen gas concentration of hydrogen gas that diffuses through the gap H and leaks out of the container 15 from the opening 15A is 0.01 vol% or more and 10 vol% or less. This allows the amount of hydrogen gas present in the container 15 to be set within a range in which the hydrogen gas concentration sensor 10 of the present invention operates appropriately.

[0028] The above-mentioned gap H can be formed, for example, by utilizing the difference in thermal expansion between the material constituting the container 15 and the first electrode material constituting the first electrode piece 11. There are also methods of making grooves on the side of the first electrode piece 11, or preparing a plurality of first electrode pieces 11 and twisting them together. It can also be formed by applying porous plating to the surface of the first electrode piece 11, or by coating the surface of the first electrode piece 11 with porous ceramics / zeolite or ceramic fine particles. On the other hand, the gap H can be formed by pores of a porous material that blocks the opening 15A of the container 15. Examples of such materials include polymer membranes, porous ceramics, and zeolites.

[0029] In addition, since the detection sensitivity of the hydrogen gas concentration sensor 10 of the present invention changes depending on the environmental temperature, a linear temperature compensation third electrode 13 is provided to eliminate the influence of the environmental temperature. This third electrode 13 is also provided so as to be spaced apart from the first electrode 11 and the second electrode 12 with respect to the electrolyte 14. The third electrode 13 is an electrode for temperature compensation and is provided to offset the environmental temperature of the hydrogen gas concentration sensor 10, i.e., the environmental temperature change of the first electrode 11 which is the detection electrode, so it is preferable to make the third electrode 13 from the same material as the first electrode 11. In addition to the above-mentioned function of the temperature compensation electrode, the third electrode can also function to detect the concentration of hydrogen gas diffused in the container 15B.

[0030] The first electrode piece 11, the second electrode piece 12, and the third electrode piece 13 are arranged to extend outside the container 15 from the rear end opening of the container 15 opposite the sealed portion of the container 15 in order to measure the electromotive force associated with the detection of hydrogen gas concentration.

[0031] The hydrogen concentration of the hydrogen gas concentration sensor 10 of this embodiment is detected by the electromotive force generated between the first electrode piece 11 and the second electrode piece 12, and this electromotive force is generated based on the following relational expression.

[0032]

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[0033] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these.

[0034] A hydrogen gas concentration sensor 10 shown in Fig. 1 was prepared and a simple hydrogen gas detection test was carried out. The first electrode piece 11 was a platinum wire with a diameter of 0.2 mm, and the second electrode piece 12 was a tungsten wire with a diameter of 0.2 mm. For simplification, the third electrode piece 13 was omitted.

[0035] Next, the first electrode piece 11 and the second electrode piece 12 were arranged in an electrolyte 14 made of cesium phosphotungstate with a gap of 0.2 mm between them. Furthermore, the first electrode piece 11, the second electrode piece 12 and the electrolyte 14 were housed and arranged in a glass tube 15 having a diameter of 6 mm and a length of 25 mm, and the first electrode piece 11 was exposed from an opening 15A of the glass tube 15 by a length of 3 mm.

[0036] Furthermore, it was confirmed that when the opposite side 15B of opening 15A of container 15, which is the end of the container, is opened to atmospheric pressure, and when the inside of opposite side 15B of container 15 is at atmospheric pressure and the hydrogen concentration is 85 vol%, the equilibrium hydrogen gas concentration of hydrogen gas that diffuses through gap H and leaks from opening 15A to the outside of container 15 is 0.01 vol% or more and 10 vol% or less.

[0037] Figure 2 shows the detection voltage (V) when a platinum wire is used as the first electrode piece 11. As shown in Figure 2, when a platinum wire is used as the first electrode piece 11, it is understood that the detection voltage decreases as the detected hydrogen gas concentration increases from 0 vol% to 100 vol%, that is, it is understood that the platinum wire is suitable as a detection electrode for a hydrogen gas concentration sensor with high response.

[0038] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0039] 10 Hydrogen gas concentration sensor 11 First electrode piece 12 Second electrode piece 13 Third electrode piece 14 Electrolytes 15 Container 15A opening 15B open end

Claims

1. a first electrode piece and a second electrode piece, an electrolyte in which the electrodes are disposed apart from each other, and a container that contains the first electrode piece, the second electrode piece, and the electrolyte; The first electrode piece is H 2 (-)|50mol / m 3 H 2 SO 4 | A first electrode material having a standard electromotive force value of 0.8 V or more when the cell is made of the substance sample (+), The second electrode includes a second electrode material that exhibits a standard electromotive force value of less than 0.8 V in a cell having the same configuration; the first electrode piece penetrates the electrolyte, and an electrode end of the first electrode piece is exposed to the outside from a container end of the container; A hydrogen gas concentration sensor, comprising: a gap formed between the first electrode piece and the end of the container.

2. 2. The hydrogen gas concentration sensor according to claim 1, wherein hydrogen gas diffuses into the container through the gap, and a three-phase interface of hydrogen gas / electrolyte / first electrode piece is formed.

3. The hydrogen gas concentration sensor of claim 1 or 2, characterized in that the size of the gap is such that when the opposite side of the container to the container end is opened to atmospheric pressure, and the inside of the container on the opposite side is at atmospheric pressure and a hydrogen concentration of 85 vol%, the equilibrium hydrogen gas concentration of hydrogen gas diffusing through the gap and leaking outside the container is 0.01 vol% or more and 10 vol% or less.

4. 4. The hydrogen gas sensor according to claim 3, wherein the gap is formed by pores in a porous material that closes the end of the container.

5. 3. The hydrogen gas concentration sensor according to claim 1, wherein the first electrode material includes at least one of platinum, a platinum alloy, and a material containing these.

6. 3. The hydrogen gas concentration sensor according to claim 1, wherein the second electrode material includes at least one of tungsten, a tungsten alloy, nickel, a nickel alloy, titanium, a titanium alloy, copper, a copper alloy, iron, an iron alloy, aluminum, an aluminum alloy, and materials containing these.

7. 3. The hydrogen gas concentration sensor according to claim 1, further comprising a third electrode piece housed in the container and disposed in the electrolyte.

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