JP2013170957A - Electrochemical gas sensor element and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrochemical gas sensor element capable of maintaining excellent detection performance while reducing a used amount of a catalyst.SOLUTION: An electrochemical gas sensor element 1 includes: an electrolyte; a first electrode 21 connecting to the electrolyte and a detection object in gas; and a second electrode 22 connecting to the electrolyte. The first electrode 21 includes a first conductive layer formed of carbon powder and binder, and a first metal catalyst carried on the first conductive layer. The first metal catalyst is carried on the first conductive layer by being formed by an electrodeposition method.

Description

  The present invention relates to an electrochemical gas sensor element used for electrochemically detecting a detection target in a gas and a method for manufacturing the same.

  Conventionally, as a method for detecting a detection target in gas, there is a method for electrochemically detecting a detection target in gas using an electrochemical gas sensor element. Since the electrochemical gas sensor element does not need to be heated, it consumes less power than a semiconductor gas sensor or a catalytic combustion type gas sensor. For this reason, the electrochemical gas sensor element can be driven for a long time even when power is supplied from the battery. The output of the electrochemical gas sensor element is linear with respect to the gas concentration. For this reason, the electrochemical gas sensor element is evaluated as a sensor that is very easy to use.

  An electrochemical gas sensor basically includes a working electrode, a counter electrode, and an electrolyte. Conventionally, the working electrode and the counter electrode are formed from a kneaded body of, for example, carbon black, a particulate catalyst such as platinum black as a noble metal catalyst component, and a fluorine-based binder. However, in that case, since a rare and expensive particulate catalyst is used in a large amount in order to increase the reactivity with the gas, there is a problem from the viewpoint of reducing the manufacturing cost and saving resources. .

  Patent Document 1 discloses that an electrode catalyst layer is formed on the surface of a kneaded body film of carbon black fine powder and fluororesin fine powder by vapor deposition, sputtering, ion plating, or the like.

  However, in the method described in Patent Document 1, it is possible to reduce the amount of catalyst by adjusting the conditions for forming the electrode catalyst layer, but it is difficult to sufficiently improve the sensitivity of the electrochemical gas sensor. . This is presumably because the catalyst component is formed only on the outermost surface of the membrane, so that the probability of contact reaction with gas deteriorates. Moreover, since the electrode catalyst layer in Patent Document 1 is vulnerable to poisoning and physical impact, there is a problem in terms of life.

JP 2005-134248 A

  The present invention has been made in view of the above-mentioned reasons, and the object thereof is an electrochemical gas sensor element capable of maintaining good detection performance while reducing the amount of catalyst used, and such an electrochemical formula. It is providing the manufacturing method of a gas sensor element.

The electrochemical gas sensor element 1 according to the present invention is an electrochemical gas sensor element 1 including an electrolytic solution, a first electrode 21 in contact with a gas containing the electrolytic solution and a detection target, and a second electrode 22 in contact with the electrolytic solution. There,
The first electrode 21 includes a first conductive layer 31 formed of carbon powder and a binder, and a first metal catalyst supported on the first conductive layer 31, and the first metal catalyst includes: The first conductive layer 31 is supported by being formed by an electrodeposition method.

  The electrochemical gas sensor element 1 according to the present invention preferably further includes a porous layer 4 joined to the surface of the first electrode 21 that contacts the gas.

  The electrochemical gas sensor element 1 according to the present invention further includes a porous first holding layer 51 bonded to a surface of the first electrode 21 that is in contact with the electrolyte solution, and the electrolyte solution includes the first holding layer 51. It is also preferred that it permeates into.

  In the electrochemical gas sensor element 1 according to the present invention, it is also preferable that the first electrode 21 is made of a single film.

  In the electrochemical gas sensor element 1 according to the present invention, the second electrode 22 includes a second conductive layer formed of carbon powder and a binder, and a second metal catalyst supported on the second conductive layer. It is preferable that the second metal catalyst is supported on the second conductive layer by being formed by an electrodeposition method.

The electrochemical gas sensor element 1 according to the present invention is an electrochemical gas sensor element 1 including an electrolytic solution, a first electrode 21 in contact with a gas containing the electrolytic solution and a detection target, and a second electrode 22 in contact with the electrolytic solution. There,
The second electrode 22 includes a second conductive layer formed of carbon powder and a binder, and a second metal catalyst supported on the second conductive layer, and the second metal catalyst is electrodeposited. It may be characterized in that it is carried on the second conductive layer by being formed by the method.

  The electrochemical gas sensor element 1 according to the present invention further includes a porous second holding layer 52 bonded to the second electrode 22, and the electrolytic solution permeates the second holding layer 52. preferable.

  In the electrochemical gas sensor element 1 according to the present invention, it is also preferable that the second electrode 22 is made of a single film.

The electrochemical gas sensor element 1 according to the present invention further includes a cap member 6 that covers the first electrode 21.
A space 61 through which gas can flow is formed between the cap member 6 and the first electrode 21.
It is also preferable that the cap member 6 is formed with a gas supply port 62 and a gas discharge port 63 that communicate the space 61 with the outside.

The electrochemical gas sensor element 1 according to the present invention further includes a ventilation member 7 superimposed on a surface of the first electrode 21 that contacts the gas,
It is also preferable that a through hole 71 extending from the outside to the first electrode 21 is formed in the ventilation member 7.

The manufacturing method of the electrochemical gas sensor element 1 according to the present invention includes an electrolytic solution, a first electrode 21 in contact with a gas containing the electrolytic solution and a detection target, and a second electrode 22 in contact with the electrolytic solution, In the method of manufacturing the electrochemical gas sensor element 1, the one electrode 21 includes a first conductive layer 31 formed of carbon powder and a binder, and a first metal catalyst supported on the first conductive layer 31. There,
The method includes a step of supporting the first conductive layer 31 by forming the first metal catalyst by an electrodeposition method.

In the manufacturing method of the electrochemical gas sensor element 1 according to the present invention, the second electrode 22 is a second conductive layer formed of carbon powder and a binder, and a second metal supported on the second conductive layer. With a catalyst,
It is also preferable to further include the step of supporting the second metal catalyst on the second conductive layer by forming the second metal catalyst by an electrodeposition method.

The electrochemical gas sensor element 1 according to the present invention includes an electrolytic solution, a first electrode 21 in contact with a gas containing the electrolytic solution and a detection target, and a second electrode 22 in contact with the electrolytic solution, and the second electrode 22. Is a method for producing an electrochemical gas sensor element 1 comprising a second conductive layer formed of carbon powder and a binder, and a second metal catalyst supported on the second conductive layer,
The method may include a step of supporting the second metal catalyst on the second conductive layer by forming the second metal catalyst by an electrodeposition method.

  According to the present invention, good detection performance can be maintained while reducing the amount of catalyst used in the electrochemical gas sensor element 1.

It is sectional drawing which shows 1st embodiment of this invention. (A) thru | or (d) are figures which show the process of producing the 1st electrode in 1st embodiment of this invention. It is a figure which shows the process of producing a 1st electrode by electrodeposition in 1st embodiment of this invention. (A) And (b) is sectional drawing which shows the process of manufacturing the electrochemical gas sensor element which concerns on 1st embodiment of this invention. It is a bottom view which shows the cap member in 1st embodiment of this invention. It is sectional drawing which shows the modification of 1st embodiment of this invention. (A) And (b) is sectional drawing which shows the process of manufacturing the electrochemical gas sensor element which concerns on 2nd embodiment of this invention. It is sectional drawing which shows the modification of 2nd embodiment of this invention. It is a graph which shows the result of having measured the output at the time of arrange | positioning the electrochemical type gas sensor element which concerns on the Example of this invention in the gas atmosphere containing ethanol. It is a graph which shows the result of having measured the maximum output at the time of blowing the gas containing ethanol in the gas supply port of the electrochemical gas sensor element which concerns on the Example of this invention.

    First, a first embodiment of the present invention will be described.

  As shown in FIG. 1, the electrochemical gas sensor element 1 according to the present embodiment includes a first electrode 21, a second electrode 22, an electrolytic solution, a first holding layer 51, a second holding layer 52, a holding material 8, and a container 9. The first conductive wire 231, the second conductive wire 232, and the cap member 6 are provided.

  The container 9 is formed with a recess 91 that opens on the upper surface (first surface) of the container 9. The first electrode 21, the second electrode 22, the electrolytic solution, and the holding material 8 are accommodated in the recess 91. The container 9 is also formed with a hole 92 that opens on the side surface (second surface) of the container 9 and communicates with the recess 91. The material in particular of the container 9 is not restrict | limited, For example, the container 9 is formed from appropriate plastics, such as a polypropylene.

  In the recess 91, the first electrode 21, the first holding layer 51, the holding material 8, the second electrode 22, and the second holding layer 52 are laminated in this order from the first surface side (opening 93 side). . The first conductive wire 231 is connected to the first electrode 21 and is drawn out from the opening 93 on the upper surface of the container 9. The second conductive wire 232 is connected to the second electrode 22 and led out from the hole 92. The electrolytic solution is filled in the recess 91. Therefore, the second electrode 22, the first holding layer 51, the second holding layer 52, and the holding material 8 are immersed in the electrolytic solution. Only one surface of the first electrode 21 in the thickness direction is in contact with the electrolytic solution.

  The first electrode 21 includes a conductive layer 3 (first conductive layer 31) and a first metal catalyst supported on the first conductive layer 31.

  The first conductive layer 31 is formed from carbon powder and a binder. The carbon powder is not particularly limited, but carbon black powder such as acetylene black is preferable. The particle size of the carbon powder is not particularly limited, but the average particle size is preferably in the range of 10 to 100 nm, and more preferably in the range of 20 to 100 nm. The average particle diameter is measured by a dynamic light scattering layer. On the other hand, the binder is not particularly limited, but is preferably a fluorine resin such as polytetrafluoroethylene (PTFE). The first conductive layer 31 is formed from a paste-like composition 101 containing, for example, carbon powder and binder powder. For example, carbon powder and binder powder are blended, an appropriate solvent such as isohexanol is added, and these are kneaded, whereby paste-like composition 101 is obtained. In this case, it is preferable that the ratio of the binder with respect to 100 mass parts of carbon powders is the range of 100 mass parts or more and 400 mass parts or less. When this ratio is 400 parts by mass or less, the catalyst is easily supported on the first conductive layer 31 by electrodeposition. Moreover, it becomes easy to maintain the shape of the 1st conductive layer 31 because this ratio is 100 mass parts or more. For example, 10 parts by mass of acetylene black (for example, acetylene carbon powder manufactured by Denki Kagaku Kogyo Co., Ltd.) and 30 parts by mass of PTFE powder (for example, manufactured by Daikin Kogyo Co., Ltd., product number D-201) are blended, and an appropriate amount thereof is blended. Is added, and these are kneaded in a three-roll mill or the like, for example, for 10 minutes, whereby a paste-like composition 101 is obtained.

  Also, the paste-like composition 101 is obtained by blending carbon powder and an aqueous solution or aqueous dispersion containing a binder powder, adding an appropriate solvent such as isohexanol, and further kneading them. May be obtained. In this case, it is preferable that the ratio of the binder with respect to 100 mass parts of carbon powders is the range of 5-30 mass parts. For example, 10 parts by mass of acetylene black (for example, acetylene carbon powder manufactured by Denki Kagaku Kogyo Co., Ltd.) and 2 parts by weight of a PTFE aqueous solution (for example, product number D-210C manufactured by Daikin Kogyo Co., Ltd.) are blended, and an appropriate amount of By adding hexanol and further kneading them with a three roll mill or the like for 10 minutes, a paste-like composition 101 is obtained.

  The first conductive layer 31 is obtained by thermoforming the paste-like composition 101. Although the thickness in particular of the 1st conductive layer 31 is not restrict | limited, It is preferable that it is the range of 0.1 mm or more and 1 mm or less.

  It is preferable that the first conductive layer 31 and the first holding layer 51 are joined by forming the first conductive layer 31 on the first holding layer 51. The first holding layer 51 is a porous layer having electrical insulation, and is formed of, for example, a porous glass fiber sheet. The thickness of the first holding layer 51 is not particularly limited, but is preferably in the range of 0.1 mm to 3 mm.

  In one aspect of the present embodiment, when the first conductive layer 31 is manufactured, first, as shown in FIGS. 2A and 2B, a paste-like composition is formed on the transfer member 102. 101 is applied. The transfer member 102 is preferably formed of a material having high releasability, and is preferably, for example, a fluororesin sheet or a silicon resin sheet. A method for applying the paste-like composition 101 is not particularly limited, and for example, a screen printing method using a metal screen 103, a squeegee 104, or the like is employed.

  Subsequently, as shown in FIG. 2C, the first holding layer 51 is overlaid on the composition 101 on the transfer member 102. In this case, it is preferable that the end portion of the first conductive wire 231 is disposed between the first holding layer 51 and the composition 101. Although the material in particular of the 1st conductive wire 231 is not restrict | limited, For example, a platinum wire is mentioned.

  Subsequently, the first holding layer 51 and the composition 101 are heated and pressurized. In this case, for example, the transfer member 102, the composition 101, and the first holding layer 51 are disposed between a pair of heating plates 105, and together with the transfer member 102 and the first holding layer 51, the heating plate 105, The composition 101 is heated and pressed. When the composition 101 is heated and pressurized in this way, the binder in the composition 101 is melted and then solidified, whereby the sheet-like porous first conductive layer 31 is formed. Further, since the binder is melted and solidified in a state where the composition 101 is overlapped with the first holding layer 51, the first conductive layer 31 is bonded to the first holding layer 51. Further, the end portion of the first conductive wire 231 is sandwiched and fixed between the first conductive layer 31 and the first holding layer 51, whereby the first conductive layer 31 and the first conductive wire 231 are electrically connected. Connected. After molding, the transfer member 102 is peeled from the first conductive layer 31 as shown in FIG.

  In another aspect of the present embodiment, when the first conductive layer 31 is manufactured, first, the paste-like composition 101 is roll-formed while being heated, whereby a sheet-like molded body is obtained. This molded body is punched into a predetermined size and shape by a Thomson mold or the like as necessary. This molded body is overlaid on the first holding layer 51. In this case, the molded body is overlaid in a state where the end portion of the first conductive wire 231 is disposed on the first holding layer 51, so that the first conductive wire 231 is interposed between the first holding layer 51 and the molded body. It is preferable that the end portion is sandwiched.

  Subsequently, the formed body on the first holding layer 51 is heated and pressurized. In this case, for example, the molded body and the first holding layer 51 are arranged between a pair of heating plates 105, and the molded body is heated and pressed together with the first holding layer 51 by the heating plate 105. When the molded body is heated and pressurized in this manner, the binder in the molded body is melted and then solidified, whereby the sheet-like porous first conductive layer 31 is formed. In addition, the molded body is bonded to the first holding layer 51 because the binder is melted and solidified in a state where the composition 101 is overlapped with the first holding layer 51. Further, the end portion of the first conductive wire 231 is sandwiched and fixed between the first conductive layer 31 and the first holding layer 51, whereby the first conductive layer 31 and the first conductive wire 231 are electrically connected. Connected.

The heating and pressurizing conditions of the composition 101 or the molded body are appropriately set according to the composition of the composition 101 and the like. is preferably .4kPa (0.3kg / cm ²⁾ or more 196.1kPa (2kg / cm ²⁾ the range, it is preferable molding time is in the range of less than 60 seconds 10 seconds.

  After the first conductive layer 31 is formed, the first metal catalyst is supported on the first conductive layer 31. The first metal catalyst is formed on the first conductive layer 31 by the electrodeposition method, and is thereby supported on the first conductive layer 31.

  The first metal catalyst may be a metal that promotes the electrochemical reaction to be detected in the gas. The first metal catalyst is particularly preferably platinum.

  A method of supporting platinum as the first metal catalyst on the first electrode 21 by the electrodeposition method will be described with reference to FIG. First, an electrolytic solution 108 for electrodeposition is placed in the electrolytic cell 107. As the electrodeposition electrolytic solution 108, an aqueous solution of a platinum compound such as chloroplatinic acid hexahydrate is preferably used. The concentration of chloroplatinic acid hexahydrate in the electrodeposition electrolytic solution 108 is preferably in the range of 10 g / L to 50 g / L. In order for the electrodeposition electrolytic solution 108 to be easily compatible with the first conductive layer 31, it is preferable to add a surfactant, an appropriate amount of alcohol such as methanol, or the like to the electrodeposition electrolytic solution 108.

  The first conductive layer 31 and the counter electrode 109 are immersed in the electrodeposition electrolytic solution 108. For example, a platinum electrode is used as the counter electrode 109. When the first conductive layer 31 is bonded to the first holding layer 51, the first conductive layer 31 is immersed in the electrodeposition electrolytic solution 108 together with the first holding layer 51. Becomes easier to handle. A voltage is applied from the power source 110 between the first conductive layer 31 and the counter electrode 109 so that the first conductive layer 31 serves as a cathode and the counter electrode 109 serves as an anode. When the first conductive line 231 is connected to the first conductive layer 31, the first conductive line 231 can be used to supply power to the first conductive layer 31. The electrolysis conditions are appropriately set according to the composition of the electrodeposition electrolytic solution 108 and the like. As a result, the first metal catalyst is deposited on the first conductive layer 31 by an electrolytic reaction, whereby the first metal is supported on the first conductive layer 31. Subsequently, the first conductive layer 31 is pulled up from the electrodeposition electrolytic solution 108 and sufficiently washed with water. Thereby, the 1st electrode 21 provided with the 1st conductive layer 31 and the 1st metal catalyst carry | supported by this 1st conductive layer 31 is obtained.

  As described above, when the first metal catalyst is supported on the porous first conductive layer 31 by the electrodeposition method, the first metal catalyst is supported on the first electrode 21 even if the amount of the first metal catalyst supported is small. This effectively contributes to the promotion of the electrode reaction. This is because when the first metal catalyst is formed by the electrodeposition method, the electrodeposition electrolytic solution 108 penetrates into the porous first conductive layer 31 to some extent, so that the first metal catalyst becomes the first conductive layer. It is considered that this is because it is supported not only near the surface layer 31 but also inside the first conductive layer 31 and the first metal catalyst is supported in an ultrafine particle state. For this reason, even if the loading amount of the first metal catalyst is small, the surface area of the first metal catalyst becomes very large, and the gas passing through the first electrode 21 can easily come into contact with the first metal catalyst. It is considered that the first metal catalyst effectively contributes to the promotion of the electrode reaction on the first electrode 21. Further, by selecting the electrodeposition conditions (voltage, current, electrodeposition time), the adhesion state and the amount of adhesion of the first metal catalyst on the first electrode 21 can be controlled.

A preferred loading amount of the first metal catalyst is preferably in the range of 0.1 mg to 20 mg, more preferably in the range of 1 mg to 20 mg, per 1 cm ² of the projected area of the first conductive layer 31. Thus, even if the loading amount is small, the first metal catalyst can effectively contribute to the promotion of the electrode reaction on the first electrode 21. The projected area is the projected area in the direction in which the first electrode 21, the first holding layer 51, the holding material 8, the second electrode 22, and the second holding layer 52 are laminated.

  The second electrode 22 includes a second conductive layer and a second metal catalyst supported on the second conductive layer.

  The second conductive layer is formed from carbon powder and a binder. As the material and forming method for forming the second conductive layer, the above-described material and forming method for forming the first conductive layer 31 can be employed as they are.

  It is preferable that the second conductive layer and the second holding layer 52 are joined by forming the second conductive layer on the second holding layer 52. The second holding layer 52 is a porous layer having electrical insulation, and is formed of, for example, a porous glass fiber sheet. The thickness of the second holding layer 52 is not particularly limited, but is preferably in the range of 0.3 mm to 3 mm. As a method for bonding the second conductive layer and the second holding layer 52, the method for bonding the first conductive layer 31 and the first holding layer 51 may be employed as it is. In this case, the end portion of the second conductive wire 232 is sandwiched and fixed between the second conductive layer and the second holding layer 52, whereby the second conductive layer and the second conductive wire 232 are electrically connected. Is done.

  After the second conductive layer is formed, the second metal catalyst is supported on the second conductive layer. The second metal catalyst is formed on the second conductive layer by the electrodeposition method, and is thereby supported on the second conductive layer. The second metal catalyst may be a metal that promotes the electrochemical reaction of the electrolytic solution. The second metal catalyst is particularly preferably platinum. As a method of supporting platinum as the second metal catalyst on the second electrode 22 by the electrodeposition method, the method of supporting platinum as the first metal catalyst on the first electrode 21 may be employed as it is.

  Thus, when the second metal catalyst is supported on the second electrode 22 by the electrodeposition method, the second metal catalyst is used as the second electrode for the same reason as when the first metal catalyst is supported on the first electrode 21. This effectively contributes to the promotion of the electrode reaction on 22.

The preferred loading amount of the second metal catalyst is preferably in the range of 0.1 mg to 20 mg, more preferably in the range of 1 mg to 20 mg, per 1 cm ² of the projected area of the second conductive layer. Thus, even if the loading is small, the second metal catalyst can effectively contribute to the promotion of the electrode reaction on the second electrode 22.

  The holding material 8 is used to hold the electrolytic solution so as to be in stable contact with the first electrode 21 and the second electrode 22. The holding material 8 is preferably formed of a porous material that allows the electrolytic solution to penetrate by capillary action. For example, the holding material 8 is preferably formed from a glass fiber material, a porous vinyl chloride material, a porous polypropylene material, or the like.

  As shown in FIG. 4A and FIG. 4B, the second holding layer 52, the second electrode 22, the holding material 8, the first holding layer 51, and the first in the recess 91 of the container 9. By putting the electrodes 21 in this order, these elements are stacked and accommodated in the recess 91 of the container 9. In the present embodiment, since the second holding layer 52 is bonded to the second electrode 22, the second holding layer 52 and the second electrode 22 are simultaneously accommodated in the recess 91, and the first holding layer Since 51 is accommodated in the first electrode 21, the first holding layer 51 and the first electrode 21 are simultaneously accommodated in the recess 91.

  When the second holding layer 52 and the second electrode 22 are accommodated in the recess 91, the second conductive wire 232 is drawn out from the recess 91 through the hole 92. Further, when the first holding layer 51 and the first electrode 21 are accommodated in the recess 91, the first conductive wire 231 is drawn out from the opening 93 on the upper surface side of the recess 91.

  In addition, when the edge part of the 2nd conductive wire 232 is previously pinched | interposed and fixed between the 2nd conductive layer and the 2nd holding | maintenance layer 52, the 2nd conductive wire is connected to the 2nd electrode 22 with an appropriate method. The ends of 232 are connected. For example, the end of the second conductive wire 232 is connected to the second electrode 22 by sandwiching and fixing the end of the second conductive wire 232 between the second electrode 22 and the holding member 8. Further, even when the end portion of the first conductive wire 231 is not sandwiched and fixed between the first conductive layer 31 and the first holding layer 51 in advance, the first electrode 21 is connected to the first electrode 21 by an appropriate method. The ends of the line 231 are connected.

  When the second holding layer 52, the second electrode 22, the holding material 8, the first holding layer 51, and the first electrode 21 are put in the recess 91 of the container 9, the electrolytic solution is put into the container at an appropriate timing. Nine recesses 91 are supplied. As the electrolytic solution, an appropriate electrolytic solution that can be applied to the electrochemical gas sensor element 1, such as a sulfuric acid aqueous solution, a phosphoric acid aqueous solution, a sodium sulfate aqueous solution, or a potassium nitrate aqueous solution, may be used.

  The electrolytic solution penetrates into the holding material 8, the first holding layer 51, and the second holding layer 52 in the recess 91, so that these holding material 8, second holding material 82, first holding layer 51, and first It is held by the second holding layer 52. Thereby, the electrolytic solution comes into stable contact with the first electrode 21 and the second electrode 22.

  Subsequently, the cap member 6 is fixed to the container 9 by adhesion, welding or the like so that the opening 93 of the container 9 is covered by the cap member 6. A bottom view of the cap member 6 is shown in FIG. A recess 64 is formed in the cap member 6. An opening 65 communicating with the recess 91 is formed on the surface of the cap member 6 that faces the opening 93 of the container 9. A plurality of wall bodies 66 are provided in the recess 64, whereby a meandering flow path is formed in the recess 64. Further, the cap member 6 is formed with a gas supply port 62 and a gas discharge port 63 that communicate the inside of the recess 64 with the outside. The gas supply port 62 and the gas discharge port 63 communicate with one end and the other end of the flow path, respectively. The material in particular of the cap member 6 is not restrict | limited, For example, the cap member 6 is formed from suitable plastics. In particular, the cap member 6 is preferably formed from a polypropylene resin, a polyvinyl chloride resin, or the like that has high durability against an electrolytic solution such as an aqueous hydrochloric acid solution.

  The opening 65 of the container 9 is covered with the cap member 6 so that the opening 65 of the cap member 6 and the opening 93 of the container 9 overlap with each other, whereby the first electrode 21 is covered with the cap member 6. Then, a space 61 including a recess 64 is formed between the cap member 6 and the first electrode 21, and the space 61 communicates with the outside through the gas supply port 62 and the gas discharge port 63. Further, when the opening 93 of the container 9 is covered with the cap member 6 in this way, the wall body 66 of the cap member 6 abuts against the first electrode 21, whereby the second holding layer 52, within the recess 91 of the container 9, The second electrode 22, the holding material 8, the first holding layer 51, and the first electrode 21 are fixed.

  In the electrochemical gas sensor element 1 configured as described above, when a gas including a detection target is supplied from the gas supply port 62 into the space 61, the gas comes into contact with the first electrode 21, and accordingly, the first electrode 21 is in contact therewith. An electromotive force is generated between the first electrode 22 and the second electrode 22. In this case, the potential difference between the first electrode 21 and the second electrode 22, the current flowing between the first electrode 21 and the second electrode 22, etc. are transmitted via the first conductive line 231 and the second conductive line 232. Based on the detection, the detection target in the gas is detected, or the concentration of the detection target is further measured.

  In the present embodiment, the first electrode 21 may not be bonded to the first holding layer 51, and in this case, the electrochemical gas sensor element 1 may not include the first holding layer 51. When the first electrode 21 is manufactured without being bonded to the first holding layer 51, that is, when the first electrode 21 is formed as a single film, for example, first, the roll is made while the paste-like composition 101 is heated. By molding, a sheet-like molded body is obtained. This molded body is punched into a predetermined size and shape by a Thomson mold or the like as necessary. This molded body is heated and pressurized. In this case, for example, the molded body is disposed between a pair of hot plates, and the molded body is heated and pressed by the hot platen. When the molded body is heated and pressurized in this way, the binder in the molded body is melted and then solidified, whereby a single film of a sheet-like porous first conductive layer is formed.

  In this embodiment, as shown in FIG. 6, the electrochemical gas sensor element 1 may include a ventilation member 7 instead of the cap member 6. In this case, the ventilation member 7 is fixed to the container 9 by adhesion, welding, or the like so that the opening 93 of the container 9 is covered by the ventilation member 7, whereby the first electrode 21 is covered by the ventilation member 7.

  When the opening 93 of the container 9 is covered by the ventilation member 7, the ventilation member 7 presses the first electrode 21, and thereby the second holding material 82, the second holding layer 52, the second electrode in the recess 91 of the container 9. 22, the holding material 8, the first holding layer 51, and the first electrode 21 are fixed. A plurality of through holes 71 are formed in the ventilation member 7. These through holes 71 are formed so as to reach the first electrode 21 from the outside. The material in particular of the ventilation member 7 is not restrict | limited, For example, the ventilation member 7 is formed from suitable plastics.

  When the electrochemical gas sensor element 1 includes the ventilation member 7, the amount of gas supplied to the first electrode 21 by the ventilation member 7 is limited, so that the measurement range at the time of gas measurement by the electrochemical gas sensor element 1 becomes large.

  In addition, when the electrochemical gas sensor element 1 includes the ventilation member 7, a cap member 6 may be further included.

  The detection target of the electrochemical gas sensor element 1 is not particularly limited as long as it can be detected by an electrochemical technique. Examples of detection targets include alcohol, carbon monoxide, hydrogen, and the like.

  Next, a second embodiment of the present invention will be described.

  As shown in FIG. 7B, the electrochemical gas sensor element 1 according to the present embodiment includes a first electrode 21, a second electrode 22, an electrolytic solution, a second holding layer 52, a holding material 8, a porous layer 4, A container 9, a first conductive wire 231, and a second conductive wire 232 are provided. That is, the electrochemical gas sensor element 1 according to the present embodiment does not include the first holding layer 51 and the cap member 6 in the first embodiment and includes the porous layer 4.

  The container 9 is formed with a recess 91 that opens on the upper surface (first surface) of the container 9. The second electrode 22, the electrolytic solution, and the holding material 8 are accommodated in the recess 91. The container 9 is also formed with a hole 92 that opens at the side surface (second surface) of the container 9 and communicates with the recess 91.

  In the recess 91, the holding material 8, the second electrode 22, the second holding layer 52, and the first electrode 21 are laminated in this order from the first surface side (opening 93 side). Furthermore, the porous layer 4 is overlaid on the first electrode 21. The porous layer 4 is overlaid on the container 9 so as to close the opening 93 of the recess 91. The first conductive wire 231 is connected to the first electrode 21 and is drawn out to the outside. The second conductive wire 232 is connected to the second electrode 22 and led out from the hole 92. The electrolytic solution is filled in the recess 91. For this reason, the second electrode 22, the second holding layer 52, and the holding material 8 are immersed in the electrolytic solution. Only one surface of the first electrode 21 in the thickness direction is in contact with the electrolytic solution.

  As in the case of the first embodiment, the first electrode 21 includes a first conductive layer 31 and a first metal catalyst supported on the first conductive layer 31. The first conductive layer 31 is formed of carbon powder and a binder as in the first embodiment. As in the case of the first embodiment, the first conductive layer 31 is formed of a paste-like composition 101 containing, for example, carbon powder and binder powder.

  It is preferable that the first conductive layer 31 and the porous layer 4 are joined by forming the first conductive layer 31 on the porous layer 4. The porous layer 4 is a porous layer having electrical insulation. The porous layer 4 preferably has water repellency. The porous layer 4 is formed from, for example, a porous fluororesin sheet. In the market, porous fluororesin sheets having various gas permeability are provided, and these can be used as the porous layer 4.

  As a method for forming the first conductive layer 31 in the present embodiment, the method for forming the first conductive layer 31 in the first embodiment may be employed as it is. Moreover, as a method for joining the 1st conductive layer 31 and the porous layer 4 by forming the 1st conductive layer 31 in this embodiment on the porous layer 4, 1st embodiment is mentioned. A method for joining the first conductive layer 31 and the first holding layer to each other by forming the first conductive layer 31 on the first holding layer can be employed as it is. In the present embodiment, the first conductive layer 31 has a plan view dimension so that the first conductive layer 31 is accommodated in the recess 91, and the porous layer 4 has a plan view dimension in which the porous layer 4 is open. It is formed larger than the first conductive layer 31 so as to be able to close 93.

  After the first conductive layer 31 is formed, a first metal catalyst is supported on the first conductive layer 31 by an electrodeposition method. As a method for supporting the first metal catalyst on the first conductive layer 31 in the present embodiment, the method for supporting the first metal catalyst on the first conductive layer 31 in the first embodiment may be employed as it is. When the first metal catalyst is supported on the first electrode 21 by the electrodeposition method, when the first conductive layer 31 is bonded to the porous layer 4, the first conductive layer 31 is electrodeposited together with the porous layer 4. Immerse in the electrolyte. For this reason, the first conductive layer 31 is easy to handle.

  The second electrode 22 includes a second conductive layer and a second metal catalyst supported on the second conductive layer. The configuration and manufacturing method of the second electrode 22 are the same as those in the first embodiment. Further, the configuration of the holding member 8 is the same as that in the first embodiment.

  As shown in FIGS. 7A and 7B, the second holding layer 52, the second electrode 22, and the holding material 8 are put in this order in the recess 91 of the container 9, These elements are stacked and accommodated in the recess 91 of the container 9. In the present embodiment, since the second holding layer 52 is bonded to the second electrode 22, the second holding layer 52 and the second electrode 22 are simultaneously accommodated in the recess 91.

  When the second holding layer 52 and the second electrode 22 are accommodated in the recess 91, the second conductive wire 232 is drawn out from the recess 91 through the hole 92. In addition, when the edge part of the 2nd conductive wire 232 is previously pinched | interposed and fixed between the 2nd conductive layer and the 2nd holding | maintenance layer 52, the 2nd conductive wire is connected to the 2nd electrode 22 with an appropriate method. The ends of 232 are connected. For example, the end of the second conductive wire 232 is connected to the second electrode 22 by sandwiching and fixing the end of the second conductive wire 232 between the second electrode 22 and the holding member 8.

  When the second holding material 82, the second holding layer 52, the second electrode 22, and the holding material 8 are put into the recess 91 of the container 9, the electrolyte solution enters the recess 91 of the container 9 at an appropriate timing. To be supplied. As the electrolytic solution, an appropriate electrolytic solution that can be applied to the electrochemical gas sensor element 1, such as a sulfuric acid aqueous solution, a phosphoric acid aqueous solution, a sodium sulfate aqueous solution, or a potassium nitrate aqueous solution, may be used.

  Subsequently, the first electrode 21 is stacked on the container 9 so as to close the opening 93 of the recess 91, and the porous layer 4 is stacked on the first electrode 21. When the porous layer 4 is bonded to the first electrode 21, the first electrode 21 and the porous layer 4 are simultaneously stacked on the container 9. Further, the first conductive wire 231 is drawn out to the outside. In addition, when the edge part of the 1st conductive wire 231 is previously pinched | interposed between the 1st conductive layer 31 and the porous layer 4, and is not fixed, the 1st conductive wire is connected to the 1st electrode 21 with an appropriate method. The end of 231 is connected. For example, the end of the second conductive wire 232 is sandwiched and fixed between the first electrode 21 and the holding member 8, so that the end of the first conductive wire 231 is connected to the first electrode 21.

  In the electrochemical gas sensor element 1 configured as described above, the electrolytic solution penetrates into the holding material 8, the second holding material 82, and the second holding layer 52 in the recess 91, so that these holding material 8, The two holding materials 82, the first holding layer 51, and the second holding layer 52 are held. Thereby, the electrolytic solution comes into stable contact with the first electrode 21 and the second electrode 22.

  In the electrochemical gas sensor element 1 configured as described above, when the gas including the detection target contacts the porous layer 4, the gas reaches the first electrode 21 through the porous layer 4. When this gas contacts the first electrode 21, an electromotive force is generated between the first electrode 21 and the second electrode 22 accordingly. In this case, the potential difference between the first electrode 21 and the second electrode 22, the current flowing between the first electrode 21 and the second electrode 22, etc. are transmitted via the first conductive line 231 and the second conductive line 232. Based on the detection, the detection target in the gas is detected, or the concentration of the detection target is further measured.

  In the present embodiment, evaporation of the electrolyte is suppressed by the porous layer 4. Further, since the amount of gas supplied to the first electrode 21 is limited by the porous layer 4, the measurement range at the time of gas measurement by the electrochemical gas sensor element 1 becomes large.

  In this embodiment, the electrochemical gas sensor element 1 may further include a cap member 6 as in the first embodiment.

  Moreover, in this embodiment, as shown in FIG. 8, the ventilation member 7 may be provided so as to overlap the porous layer 4 as in the case shown in FIG. In this case, since the amount of gas supplied to the first electrode 21 by the ventilation member 7 is further limited, the measurement range at the time of gas measurement by the electrochemical gas sensor element 1 is further increased.

[Preparation of conductive layer]
10 g of acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size 20 nm) and 30 g of PTFE powder (manufactured by Daikin Kogyo Co., Ltd., product number F104) were blended, and an appropriate amount of isohexanol was added thereto. The resulting mixture was kneaded with a three roll mill for 10 minutes. Thereby, a paste-like composition was obtained.

  This paste-like composition was applied on a silicon resin sheet by a screen printing method using a metal screen 103 having a thickness of 1 mm and an opening diameter of 20 mm.

A porous glass fiber sheet (thickness 1 mm) is overlaid on the composition on the silicon resin sheet, and an end of a platinum wire having a length of 20 mm and a diameter of 60 μm is provided between the composition and the porous glass fiber sheet. Was sandwiched. These were heated and pressed under the conditions of a heating temperature of 220 ° C., a pressure of 49.0 kPa (0.5 kg / cm ² ), and a molding time of 30 seconds. Thus, the composition was molded to form a conductive layer, a porous glass fiber sheet was bonded to the conductive layer, and a platinum wire was further connected to the conductive layer.

[Supporting metal catalyst]
An electrolytic solution for electrodeposition was obtained by dissolving 2 g of chloroplatinic acid hexahydrate in 100 cm ³ of distilled water and adding an equivalent amount of a surfactant and methanol.

A 100 cm ³ electrodeposition electrolytic solution is placed in a glass beaker, and further, a 50 mm long, 10 mm wide, 50 μm thick platinum electrode and a conductive layer are immersed in the electrodeposition electrolytic solution, and an anode of a DC power source is provided. The cathode of this direct current power source was connected to the conductive layer to the platinum electrode. While maintaining the temperature of the electrodeposition electrolytic solution at 35 ° C., a current of 50 mA was applied for 4 minutes by applying a voltage between the platinum electrode and the conductive layer from a DC power source. Subsequently, the conductive layer was washed with distilled water and then air-dried. Thereby, an electrode provided with a conductive layer and a metal catalyst supported on the conductive layer was obtained.

  By this method, a first electrode and a second electrode were obtained.

[Assembly of electrochemical gas sensor element]
A container provided with a recess having an opening diameter of 20 mm and a depth of 3 mm and having a side surface formed with a hole communicating with the recess was prepared. Place the second electrode in the recess of this container so that the porous glass fiber sheet superimposed on this second electrode is placed on the lower side, and connect the platinum wire connected to this second electrode The container was pulled out from the hole of the container. Subsequently, a glass fiber material having a thickness of 1 mm was placed in the recess. Subsequently, an aqueous sulfuric acid solution was placed as an electrolytic solution in the recess. Then, the 1st electrode was arrange | positioned so that the porous glass fiber sheet piled up on this 1st electrode might be arrange | positioned below in a recess. Furthermore, the opening of the container was covered with a cap member. Thus, an electrochemical gas sensor element having the structure shown in FIG. 1 was obtained.

[Evaluation]
(Batch measurement)
The output of the electrochemical gas sensor element was measured when the electrochemical gas sensor element was placed in an atmosphere filled with a gas containing ethanol. The result is shown in the graph of FIG. In this graph, the horizontal axis indicates the concentration of ethanol in the atmosphere. In this graph, the vertical axis represents the output of the electrochemical gas sensor element. This output is amplified by an amplifier circuit, and the baseline of this output is adjusted to 1V.

  As shown from this result, when the electrochemical gas sensor element was placed in a gas atmosphere including the detection target, the output of the electrochemical gas sensor element was linear and the sensitivity was good.

(Blow measurement)
The maximum output of the electrochemical gas sensor element was measured when 0.5 cm ³ of gas containing ethanol was blown into the gas supply port of the cap in the electrochemical gas sensor element. The result is shown in the graph of FIG. In this graph, the horizontal axis indicates the concentration of ethanol in the gas blown into the gas supply port. In this graph, the vertical axis represents the output of the electrochemical gas sensor element. This output is amplified by an amplifier circuit, and the baseline of this output is adjusted to 1V.

  As shown from this result, even when the gas including the detection target was blown into the gas supply port of the electrochemical gas sensor element, the output of the electrochemical gas sensor element was linear and the sensitivity was good.

DESCRIPTION OF SYMBOLS 1 Electrochemical gas sensor element 21 1st electrode 22 2nd electrode 31 1st conductive layer 4 Porous layer 51 1st holding layer 52 2nd holding layer 6 Cap member 61 Space 62 Gas supply port 63 Gas discharge port 7 Ventilation member 71 Through Hole

Claims (13)

An electrochemical gas sensor element comprising: an electrolytic solution; a first electrode in contact with the detection target in the electrolytic solution and gas; and a second electrode in contact with the electrolytic solution,
The first electrode includes a first conductive layer formed of carbon powder and a binder, and a first metal catalyst supported on the first conductive layer, and the first metal catalyst is an electrodeposition method. The electrochemical gas sensor element, wherein the electrochemical gas sensor element is carried by the first conductive layer. The electrochemical gas sensor element according to claim 1, further comprising a porous layer bonded to a surface of the first electrode that contacts the gas. 2. The electrochemical gas sensor according to claim 1, further comprising a porous first holding layer bonded to a surface of the first electrode in contact with the electrolyte solution, wherein the electrolyte solution penetrates the first holding layer. element. The electrochemical gas sensor element according to claim 1, wherein the first electrode is made of a single film. The second electrode includes a second conductive layer formed of carbon powder and a binder, and a second metal catalyst supported on the second conductive layer, and the second metal catalyst is an electrodeposition method. 5. The electrochemical gas sensor element according to claim 1, wherein the electrochemical gas sensor element is carried by the second conductive layer. An electrochemical gas sensor element comprising an electrolytic solution, a first electrode in contact with the detection target in the electrolytic solution and gas, and a second electrode in contact with the electrolytic solution,
The second electrode includes a second conductive layer formed of carbon powder and a binder, and a second metal catalyst supported on the second conductive layer, and the second metal catalyst is an electrodeposition method. The electrochemical gas sensor element, wherein the electrochemical gas sensor element is carried by the second conductive layer. The electrochemical gas sensor element according to claim 5 or 6, further comprising a porous second holding layer bonded to the second electrode, wherein the electrolytic solution permeates the second holding layer. The electrochemical gas sensor element according to claim 5 or 6, wherein the second electrode is made of a single film. A cap member covering the first electrode;
A space through which gas can flow is formed between the cap member and the first electrode,
The electrochemical gas sensor element according to any one of claims 1 to 8, wherein the cap member is formed with a gas supply port and a gas discharge port for communicating the space with the outside. A ventilation member superimposed on a surface of the first electrode that contacts the gas;
The electrochemical gas sensor element according to any one of claims 1 to 8, wherein a through-hole extending from the outside to the first electrode is formed in the ventilation member. A first electrode in contact with the electrolytic solution and a detection target in the gas; and a second electrode in contact with the electrolytic solution, wherein the first electrode is formed of carbon powder and a binder. A method for producing an electrochemical gas sensor element comprising a conductive layer and a first metal catalyst supported on the first conductive layer,
A method for producing an electrochemical gas sensor element, comprising the step of supporting the first conductive layer by forming the first metal catalyst by an electrodeposition method. The second electrode includes a second conductive layer formed of carbon powder and a binder, and a second metal catalyst supported on the second conductive layer,
The method for producing an electrochemical gas sensor element according to claim 11, further comprising a step of supporting the second conductive catalyst on the second conductive layer by forming the second metal catalyst by an electrodeposition method. A second electrode comprising an electrolytic solution, a first electrode in contact with the electrolytic solution and a detection target in the gas, and a second electrode in contact with the electrolytic solution, wherein the second electrode is formed of carbon powder and a binder. A method for producing an electrochemical gas sensor element comprising a conductive layer and a second metal catalyst supported on the second conductive layer,
A method for producing an electrochemical gas sensor element, comprising the step of supporting the second conductive layer on the second conductive layer by forming the second metal catalyst by an electrodeposition method.

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