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WO2019008749A1 - Semiconductor-type gas sensor - Google Patents

Semiconductor-type gas sensor Download PDF

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Publication number
WO2019008749A1
WO2019008749A1 PCT/JP2017/024987 JP2017024987W WO2019008749A1 WO 2019008749 A1 WO2019008749 A1 WO 2019008749A1 JP 2017024987 W JP2017024987 W JP 2017024987W WO 2019008749 A1 WO2019008749 A1 WO 2019008749A1
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Prior art keywords
ionic liquid
semiconductor layer
gas
gas sensor
complex
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PCT/JP2017/024987
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French (fr)
Japanese (ja)
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孝介 丹羽
近藤　順悟
達也 菱木
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日本碍子株式会社
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Priority to PCT/JP2017/024987 priority Critical patent/WO2019008749A1/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid

Definitions

  • the present invention relates to a semiconductor gas sensor.
  • Non-Patent Document 1 As a semiconductor type gas sensor, a sense comprising a pair of gold electrodes provided on the upper surface of an alumina substrate and a tin oxide provided to be in contact with the pair of gold electrodes It is known to have a gas portion and a heater provided on the lower surface of the alumina substrate.
  • a reducing gas such as a flammable gas (e.g., H 2 )
  • an oxidation reaction by the adsorbed oxygen of these gases occurs on the surface of the tin oxide.
  • oxygen adsorbed to the surface of tin oxide is reduced, the potential barrier is lowered, electrons are easily moved, and the electrical resistance is lowered.
  • the sensor resistance value also changes as the gas concentration changes. Therefore, the gas concentration can be obtained from the sensor resistance value.
  • Non-Patent Document 1 it is difficult to measure a specific gas in which different types of reducing gases are mixed. This is due to the fact that the oxidation reaction of the reducing gas by the adsorbed oxygen on the surface of tin oxide occurs regardless of the type of reducing gas. Therefore, development of the semiconductor type gas sensor which can detect a specific gas selectively is desired. Moreover, although the use environment of such a semiconductor type gas sensor varies, it was also desired that it could be able to withstand such a use environment.
  • the present invention has been made to solve such problems, and has as its main object to provide a semiconductor gas sensor capable of selectively detecting a specific gas and having high durability.
  • the semiconductor gas sensor of the present invention is A pair of electrodes provided on the surface of the substrate; An oxide semiconductor layer provided to be in contact with the pair of electrodes; A linker moiety covalently bonded to the surface of the oxide semiconductor layer at a first binding site; An ionic liquid covalently bonded to the linker moiety at a second binding site different from the first binding site in the linker moiety; A metal complex which has the property of selectively trapping a specific gas, and which is immobilized via the ionic liquid, Is provided.
  • the linker portion is covalently bonded to the surface of the oxide semiconductor layer
  • the ionic liquid is covalently bonded to the linker portion
  • the metal complex is immobilized via the ionic liquid.
  • the metal complex has the property of selectively trapping a specific gas.
  • concentration of the specific gas is changed, the surface potential on the oxide semiconductor layer is changed according to the concentration, and the current flowing between the pair of electrodes in contact with the oxide semiconductor layer is changed. Therefore, the concentration of a specific gas can be determined from the current flowing between the pair of electrodes.
  • the ionic liquid on which the metal complex is immobilized is covalently bonded to the oxide semiconductor layer through the linker portion, the bonding strength is strong and the durability is high. Therefore, according to the present invention, it is possible to provide a semiconductor gas sensor capable of selectively detecting a specific gas and having high durability.
  • the oxide semiconductor layer is preferably a porous body.
  • the surface area per unit volume is increased as compared to the case where the oxide semiconductor layer is a dense body. Therefore, the amounts of the linker portion bonded to the oxide semiconductor layer, the ionic liquid, and the metal complex immobilized on the ionic liquid are also larger than those in the case of the dense body, and the detectable gas concentration range is broadened.
  • the oxide semiconductor layer is preferably a layer of tin oxide, titanium oxide, tungsten oxide, iridium tin oxide or zinc tin oxide. These materials have a suitable work function and electron affinity for the electron affinity of a specific gas (the gas to be measured), and thus are suitable for detecting a specific gas.
  • the combination of the ionic liquid and the metal complex is a combination of a phosphonium type ionic liquid and a tetracoordinated Co complex, or an ammonium type ionic liquid and a hexacoordinated Fe
  • a combination with a -Fe complex as a combination of an ionic liquid of pyrrolidinium type with a Ti complex of four coordination, or as a combination of an ionic liquid of imidazolium type with a Ru complex of six coordination It is also good.
  • the tetracoordinated Co complex selectively traps NO gas.
  • the six-coordinated Fe-Fe complex selectively captures O 2 gas.
  • the tetracoordinated Ti complex selectively captures N 2 gas.
  • the six-coordinate Ru complex selectively captures NH 3 gas.
  • FIG. 1 is a cross-sectional view showing a schematic configuration of a semiconductor gas sensor 10;
  • FIG. 8 is an enlarged cross-sectional view of the vicinity of the surface of the oxide semiconductor layer 22;
  • Explanatory drawing which shows typical reaction formula with the oxide semiconductor layer 22, the coupling agent 23, and the ionic liquid 26.
  • FIG. Explanatory drawing which showed typically the surface of the tin oxide layer (oxide semiconductor layer 22) of Example 1.
  • FIG. 1 is a cross-sectional view showing a schematic configuration of the semiconductor gas sensor 10 of the present embodiment
  • FIG. 2 is an enlarged cross-sectional view of the vicinity of the surface of the oxide semiconductor layer 22
  • FIG. 6 is an explanatory view showing a schematic reaction formula with a liquid 26.
  • the semiconductor gas sensor 10 includes the substrate 12, the pair of electrodes 14 and 16, the oxide semiconductor layer 22, the linker portion 24, the ionic liquid 26, and the metal complex 28. Is equipped.
  • the substrate 12 is a plate-like member formed of, for example, an insulating material such as ceramics.
  • the shape of the substrate 12 in plan view is not particularly limited, and may be, for example, circular or rectangular.
  • the pair of electrodes 14 and 16 are provided on the surface of the substrate 12 so as to be separated by a predetermined distance.
  • the pair of electrodes 14 and 16 are formed of, for example, a conductive material such as platinum, gold, silver, copper or the like.
  • the shape of the pair of electrodes 14 and 16 in plan view is not particularly limited, and may be, for example, a comb shape or a rectangular shape.
  • the oxide semiconductor layer 22 covers the entire surface of the substrate 12 and is in contact with the pair of electrodes 14 and 16.
  • the thickness of the oxide semiconductor layer 22 is not particularly limited, and is, for example, 0.1 ⁇ m to 5 ⁇ m.
  • the oxide semiconductor layer 22 is a porous body, and has a large number of holes 22a on the surface as shown in FIG.
  • the oxide semiconductor layer 22 has a large surface area per unit volume as compared to the case where the holes 22 a are not provided.
  • the porosity of the oxide semiconductor layer 22 is not particularly limited, but is, for example, preferably 10% or more, and more preferably 30% or more and 70% or less.
  • the holes 22a may be open pores or closed pores.
  • the material constituting the oxide semiconductor layer 22 is not particularly limited as long as it is a semiconductor, for example, tin oxide (SnO 2), titanium oxide (TiO 2), tungsten oxide (WO 3), iridium tin oxide (ITO), zinc tin oxide (Zn 2 SnO 4 ), and the like.
  • the size of the holes 22a is preferably a size that allows the metal complex 28 to be immobilized on the surface of the holes 22a via the linker portion 24 and the ionic liquid 26, and should be 0.01 ⁇ m to 10 ⁇ m. Preferably, it is more preferably 0.05 ⁇ m or more and 1 ⁇ m or less.
  • the linker portion 24 is covalently bonded to the surface of the oxide semiconductor layer 22 at the first bonding site B 1, and is covalently bonded to the ionic liquid 26 at the second bonding site B 2.
  • the linker portion 24 includes an intermediate portion 24a between the first binding site B1 and the second binding site B2.
  • the middle part 24a contains at least one or more atoms of C, O, S and N.
  • the intermediate portion 24a may have a linear portion, and may further have a side chain in a form to be bonded to the linear portion, in which case the number of atoms constituting the linear portion is 20 or less Is preferred.
  • the specific bonding form of the first bonding site B1 is not particularly limited, but since the OH group appears on the surface of the oxide semiconductor layer 22, for example, an ether bond, an ester bond, a siloxane bond, etc. It can be mentioned.
  • the ether bond is a dehydration condensation of the OH group and the OH group on the surface of the oxide semiconductor layer 22 when Z of the divalent coupling agent 23 that is the source of the linker portion 24 in FIG. 3 is an OH group.
  • the ester bond is formed by condensation of Z with the OH group on the surface of the oxide semiconductor layer 22 when Z of the coupling agent 23 is an acid halide, carboxylic acid, ester or succinimidyl ester.
  • the siloxane bond is formed by condensation of the alkoxysilane and the OH group on the surface of the oxide semiconductor layer 22 when Z of the coupling agent 23 is an alkoxysilane.
  • the specific binding form of the second binding site B2 is also not particularly limited, but in FIG. 3, the functional form X of the divalent coupling agent 23 and the functional group Y contained in the ionic liquid 26 It is determined.
  • a typical combination example when the coupling agent 23 is represented by R 1 -X, the ionic liquid 26 is represented by R 2 -Y, and the structure in which both are linked is represented by R 1 -B2-R 2 is shown in Table 1.
  • the ionic liquid 26 is covalently bonded to the linker portion 24 at a second binding site B2 different from the first binding site B1 in the linker portion 24.
  • a material capable of immobilizing the metal complex 28 is used as the ionic liquid 26.
  • the metal complex 28 has a property of selectively capturing a gas to be detected, and is immobilized between the ionic liquid 26.
  • the metal complex 28 is a four-coordinate Co complex, it is preferable to use a phosphonium type ionic liquid. These Co complexes selectively trap NO gas.
  • An example is a combination of the ionic liquid of formula (1) and the Co complex of formula (2).
  • the metal complex 28 is a hexa-coordinated Fe--Fe complex (a complex having two Fe in its core)
  • an ammonium type ionic liquid These Fe-Fe complexes selectively trap O 2 gas.
  • One example is the combination of the ionic liquid of formula (3) with the Fe-Fe complex of formula (4).
  • the metal complex 28 is a tetracoordinate Ti complex
  • These Ti complexes selectively trap N 2 gas.
  • One example is a combination of 1-butyl-1-methylpyrrolidinium tris (pentafluoroethyl) trifluorophosphate and Cp 2 TiCl 2 (Cp is a cyclopentadienyl group).
  • the metal complex 28 is a six-coordinate Ru complex
  • These Ru complexes selectively trap NH 3 gas.
  • One example is the combination of 1-butyl-3-methylimidazolium hexafluorophosphate and tris (2,2'-bipyridyl) ruthenium (II) chloride.
  • the pair of electrodes 14 and 16 are connected to the DC power supply 30, and the ammeter 40 is connected in series. Then, a mixed gas containing a specific gas selectively trapped in the metal complex 28 is brought into contact with the metal complex 28. Then, a specific gas in the mixed gas is trapped by the metal complex 28.
  • the concentration of the specific gas changes, the surface potential on the oxide semiconductor layer 22 changes according to the concentration, and the current flowing between the pair of electrodes 14 and 16 in contact with the oxide semiconductor layer 22 Change. Therefore, if the current flowing between the pair of electrodes 14 and 16 is measured by the ammeter 40, the concentration of a specific gas can be determined.
  • a gate electrode may be provided above the metal complex 28 separately from the pair of electrodes 14 and 16.
  • gas molecules trapped in the metal complex 28 can be released.
  • the gas can be returned to the initial state in which the gas is not trapped by the metal complex 28, and the semiconductor gas sensor 10 can be regenerated.
  • the semiconductor type gas sensor 10 of the present embodiment described above it is possible to selectively detect a specific (detection target) gas contained in the mixed gas.
  • the oxide semiconductor layer 22 and the ionic liquid 26 are covalently bonded to the linker portion 24 at the first bonding site B1 and the second bonding site B2, respectively. Such covalent bonds have high bonding strength and thus have high resistance to voltage and high temperature. Therefore, the semiconductor gas sensor 10 is excellent in durability.
  • the oxide semiconductor layer 22 is a porous body, the surface area per unit volume is larger than that of a dense body. Therefore, the amount of the linker portion 24 bonded to the oxide semiconductor layer 22, the ionic liquid 26, and the amount of the metal complex 28 immobilized on the ionic liquid 26 are also larger than in the case of the dense body, and the detectable gas concentration range Becomes wider.
  • the detection sensitivity can be further improved, and the reaction efficiency with a gas can be further improved.
  • the semiconductor gas sensor 10 can be miniaturized.
  • a porous body is used as the oxide semiconductor layer 22, but a dense body may be used.
  • the detectable gas concentration range is narrowed because the surface area per unit volume is smaller than that of the porous body, but the durability is higher than that of the conventional product.
  • the linker portion 24 has a structure including the intermediate portion 24a between the first binding site B1 and the second binding site B2, but the first binding site B1 and the second binding site B2 It may be a directly coupled structure.
  • metal complex 28 that fits NO gas or the like
  • other gases be appropriately selected metal complex 28 (for example H 2, N 2 O, etc. CO 2) also detected It becomes possible. At that time, it can be implemented by selecting an appropriate ionic liquid and immobilizing the metal complex on the electrode surface through the ionic liquid.
  • Example 1 Semiconductor Gas Sensor A pair of comb-shaped Pt electrodes were formed to a thickness of 1 ⁇ m on the surface of an alumina substrate having a thickness of 0.3 mm (interelectrode distance 0.2 mm) to obtain a substrate with electrodes. Next, tin oxide powder having an average particle size of 0.3 ⁇ m is added to water together with an appropriate amount of dispersant and dispersed by ultrasonication etc. Next, a tin oxide sol having a primary particle size of 5 to 10 nm is added and mixed, It was a slurry for film formation. Next, a film forming slurry is dropped on a substrate with a high speed rotation by spin coating process, dried and heat treated at 200 to 400 ° C.
  • porous tin oxide layer covering a pair of Pt electrodes, and oxidation A tin layer coated substrate was obtained.
  • the porous tin oxide layer had an average pore diameter of 0.1 ⁇ m, a thickness of 1 ⁇ m, and a surface area per unit volume of about 105 cm 2 .
  • the tin oxide layer-coated substrate is immersed in a piranha solution (concentrated sulfuric acid: 30%, mixed with hydrogen peroxide 3: 1) for 2 hours, washed with pure water and methanol, and sprayed with nitrogen gas. It dried quickly.
  • a piranha solution concentrated sulfuric acid: 30%, mixed with hydrogen peroxide 3: 1
  • the dried tin oxide layer-coated substrate was immersed in a toluene solution (70 ° C.) mixed with a silane coupling agent for about 3 hours.
  • a silane coupling agent 3-glycidoxypropyltrimethoxysilane (KBM-403) manufactured by Shin-Etsu Chemical Co., Ltd. was used.
  • the resultant was rinsed with chloroform, water and methanol, and was quickly dried by blowing nitrogen gas. Thereby, 3-glycidoxypropyl was immobilized by siloxane bond on the surface of the tin oxide layer coated substrate.
  • the amino group of the ionic liquid forms a linker (-CH 2 CH (OH) CH 2 OC 3 H 6 SiO-, where Si is a siloxane bond) by the epoxy ring-opening reaction of the amino group of the ionic liquid with glycide. ) Is fixed to the tin oxide layer coated substrate. After that, it was washed with ethanol and chloroform to remove excess ionic liquid.
  • NO was detected using the semiconductor gas sensor of Example 1.
  • NO gas a standard gas based on JCSS (Japan Calibration Service System) was used.
  • NO gas 0.5 vol ppm, 1 vol ppm, 5 vol ppm, 10 vol ppm and 100 vol ppm diluted with nitrogen gas were prepared. In addition, 0.5 vol ppm was further diluted with nitrogen to prepare 100 vol ppb gas.
  • the NO value is 100 volppb
  • the current value is 5 ⁇ A, 0.5 vol ppm, 25 ⁇ A
  • the current value is 50 ⁇ A, 1 vol ppm
  • the current value is 250 ⁇ A
  • 10 vol ppm It was confirmed that the current value was 500 ⁇ A and 100 vol ppm and the current value was 5 mA, and it was found that the current value linearly increased as the concentration increased.
  • the present invention is applicable to gas sensors.

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Abstract

A semiconductor-type gas sensor comprising: a pair of electrodes provided on the surface of a substrate; an oxide semiconductor layer provided so as to be in contact with the pair of electrodes; a linker covalently bonded to the surface of the oxide semiconductor layer at a first bonding site; an ion fluid covalently bonded to the linker at a second bonding site on the linker that is different from the first bonding site; and a metal complex that has the property of selectively capturing a specific gas and is immobilized via the ion fluid.

Description

半導体式ガスセンサSemiconductor gas sensor
　本発明は、半導体式ガスセンサに関する。 The present invention relates to a semiconductor gas sensor.
　半導体式ガスセンサとしては、非特許文献１に開示されているように、アルミナ基板の上面に設けられた一対の金電極と、この一対の金電極に接触するように設けられた酸化スズからなる感ガス部と、アルミナ基板の下面に設けられたヒータとを備えたものが知られている。この半導体式ガスセンサでは、加熱された酸化スズが還元性ガスである可燃性ガス（例えばＨ2）に曝露されると、酸化スズの表面でこれらのガスの吸着酸素による酸化反応が起こる。その結果、酸化スズの表面に吸着していた酸素は減少してポテンシャル障壁が低下し、電子が動きやすくなり、電気抵抗が低下する。こうした半導体式ガスセンサでは、ガス濃度の変化に伴ってセンサ抵抗値も変化する。そのため、センサ抵抗値からガス濃度を求めることができる。 As disclosed in Non-Patent Document 1, as a semiconductor type gas sensor, a sense comprising a pair of gold electrodes provided on the upper surface of an alumina substrate and a tin oxide provided to be in contact with the pair of gold electrodes It is known to have a gas portion and a heater provided on the lower surface of the alumina substrate. In this semiconductor gas sensor, when the heated tin oxide is exposed to a reducing gas, such as a flammable gas (e.g., H 2 ), an oxidation reaction by the adsorbed oxygen of these gases occurs on the surface of the tin oxide. As a result, oxygen adsorbed to the surface of tin oxide is reduced, the potential barrier is lowered, electrons are easily moved, and the electrical resistance is lowered. In such a semiconductor gas sensor, the sensor resistance value also changes as the gas concentration changes. Therefore, the gas concentration can be obtained from the sensor resistance value.
　しかしながら、非特許文献１の半導体式ガスセンサでは、種類の異なる還元性ガスが混在した中で特定のガスを測定することは困難であった。これは、酸化スズの表面の吸着酸素による還元性ガスの酸化反応が還元性ガスの種類によらずに起こることに起因する。そのため、特定のガスを選択的に検出可能な半導体式ガスセンサの開発が望まれていた。また、こうした半導体式ガスセンサの使用環境は様々であるが、そうした使用環境に耐えうることも望まれていた。 However, in the semiconductor gas sensor of Non-Patent Document 1, it is difficult to measure a specific gas in which different types of reducing gases are mixed. This is due to the fact that the oxidation reaction of the reducing gas by the adsorbed oxygen on the surface of tin oxide occurs regardless of the type of reducing gas. Therefore, development of the semiconductor type gas sensor which can detect a specific gas selectively is desired. Moreover, although the use environment of such a semiconductor type gas sensor varies, it was also desired that it could be able to withstand such a use environment.
　本発明はこのような課題を解決するためになされたものであり、特定のガスを選択的に検出可能で耐久性の高い半導体式ガスセンサを提供することを主目的とする。 The present invention has been made to solve such problems, and has as its main object to provide a semiconductor gas sensor capable of selectively detecting a specific gas and having high durability.
　本発明の半導体式ガスセンサは、
　基板の表面に設けられた一対の電極と、
　前記一対の電極と接触するように設けられた酸化物半導体層と、
　前記酸化物半導体層の表面に第１結合部位で共有結合するリンカー部と、
　前記リンカー部のうち前記第１結合部位とは異なる第２結合部位で前記リンカー部と共有結合するイオン液体と、
　特定のガスを選択的に捕捉する性質を持ち、前記イオン液体を介して固定化された金属錯体と、
　を備えたものである。 The semiconductor gas sensor of the present invention is
A pair of electrodes provided on the surface of the substrate;
An oxide semiconductor layer provided to be in contact with the pair of electrodes;
A linker moiety covalently bonded to the surface of the oxide semiconductor layer at a first binding site;
An ionic liquid covalently bonded to the linker moiety at a second binding site different from the first binding site in the linker moiety;
A metal complex which has the property of selectively trapping a specific gas, and which is immobilized via the ionic liquid,
Is provided.
　この半導体式ガスセンサでは、酸化物半導体層の表面にリンカー部が共有結合し、そのリンカー部にイオン液体が共有結合し、そのイオン液体を介して金属錯体が固定化されている。金属錯体は、特定のガスを選択的に捕捉する性質を有する。その特定のガスの濃度を変化させると、その濃度に応じて酸化物半導体層上の表面電位が変化し、酸化物半導体層に接触している一対の電極間を流れる電流が変化する。そのため、一対の電極間を流れる電流から特定のガスの濃度を求めることができる。また、金属錯体が固定化されているイオン液体は、酸化物半導体層にリンカー部を介して共有結合されているため結合力が強く、耐久性が高い。したがって、本発明によれば、特定のガスを選択的に検出可能で耐久性の高い半導体式ガスセンサを提供することができる。 In this semiconductor gas sensor, the linker portion is covalently bonded to the surface of the oxide semiconductor layer, the ionic liquid is covalently bonded to the linker portion, and the metal complex is immobilized via the ionic liquid. The metal complex has the property of selectively trapping a specific gas. When the concentration of the specific gas is changed, the surface potential on the oxide semiconductor layer is changed according to the concentration, and the current flowing between the pair of electrodes in contact with the oxide semiconductor layer is changed. Therefore, the concentration of a specific gas can be determined from the current flowing between the pair of electrodes. Further, since the ionic liquid on which the metal complex is immobilized is covalently bonded to the oxide semiconductor layer through the linker portion, the bonding strength is strong and the durability is high. Therefore, according to the present invention, it is possible to provide a semiconductor gas sensor capable of selectively detecting a specific gas and having high durability.
　本発明の半導体式ガスセンサにおいて、前記酸化物半導体層は、多孔体であることが好ましい。こうすれば、酸化物半導体層が緻密体の場合に比べて、単位体積当たりの表面積が大きくなる。そのため、酸化物半導体層に結合されるリンカー部、イオン液体及びそのイオン液体に固定化される金属錯体の量も緻密体の場合に比べて多くなり、検出可能なガス濃度範囲が広くなる。 In the semiconductor gas sensor of the present invention, the oxide semiconductor layer is preferably a porous body. In this case, the surface area per unit volume is increased as compared to the case where the oxide semiconductor layer is a dense body. Therefore, the amounts of the linker portion bonded to the oxide semiconductor layer, the ionic liquid, and the metal complex immobilized on the ionic liquid are also larger than those in the case of the dense body, and the detectable gas concentration range is broadened.
　本発明の半導体式ガスセンサにおいて、前記酸化物半導体層は、酸化スズ、酸化チタン、酸化タングステン、イリジウムスズ酸化物又は亜鉛スズ酸化物の層であることが好ましい。これらの材料であれば、特定のガス（測定対象のガス）の電子親和力に対して適度な仕事関数や電子親和力があるため、特定のガスを検出するのに適している。 In the semiconductor type gas sensor of the present invention, the oxide semiconductor layer is preferably a layer of tin oxide, titanium oxide, tungsten oxide, iridium tin oxide or zinc tin oxide. These materials have a suitable work function and electron affinity for the electron affinity of a specific gas (the gas to be measured), and thus are suitable for detecting a specific gas.
　本発明の半導体式ガスセンサにおいて、前記イオン液体と前記金属錯体との組合せは、ホスホニウムタイプのイオン液体と４配位のＣｏ錯体との組合せであるか、アンモニウムタイプのイオン液体と６配位のＦｅ－Ｆｅ錯体との組合せであるか、ピロリジニウムタイプのイオン液体と４配位のＴｉ錯体との組合せであるか、又は、イミダゾリウムタイプのイオン液体と６配位のＲｕ錯体との組合せとしてもよい。４配位のＣｏ錯体は選択的にＮＯガスを捕捉する。６配位のＦｅ－Ｆｅ錯体は選択的にＯ2ガスを捕捉する。４配位のＴｉ錯体は選択的にＮ2ガスを捕捉する。６配位のＲｕ錯体は選択的にＮＨ3ガスを捕捉する。 In the semiconductor gas sensor of the present invention, the combination of the ionic liquid and the metal complex is a combination of a phosphonium type ionic liquid and a tetracoordinated Co complex, or an ammonium type ionic liquid and a hexacoordinated Fe As a combination with a -Fe complex, as a combination of an ionic liquid of pyrrolidinium type with a Ti complex of four coordination, or as a combination of an ionic liquid of imidazolium type with a Ru complex of six coordination It is also good. The tetracoordinated Co complex selectively traps NO gas. The six-coordinated Fe-Fe complex selectively captures O 2 gas. The tetracoordinated Ti complex selectively captures N 2 gas. The six-coordinate Ru complex selectively captures NH 3 gas.
半導体式ガスセンサ１０の概略構成を示す断面図。FIG. 1 is a cross-sectional view showing a schematic configuration of a semiconductor gas sensor 10; 酸化物半導体層２２の表面付近の拡大断面図。FIG. 8 is an enlarged cross-sectional view of the vicinity of the surface of the oxide semiconductor layer 22; 酸化物半導体層２２とカップリング剤２３とイオン液体２６との模式的な反応式を示す説明図。Explanatory drawing which shows typical reaction formula with the oxide semiconductor layer 22, the coupling agent 23, and the ionic liquid 26. FIG. 実施例１の酸化スズ層（酸化物半導体層２２）の表面を模式的に示した説明図。Explanatory drawing which showed typically the surface of the tin oxide layer (oxide semiconductor layer 22) of Example 1. FIG.
　本発明の好適な実施形態を、図面を参照しながら以下に説明する。図１は本実施形態の半導体式ガスセンサ１０の概略構成を示す断面図、図２は酸化物半導体層２２の表面付近の拡大断面図、図３は酸化物半導体層２２とカップリング剤２３とイオン液体２６との模式的な反応式を示す説明図である。 Preferred embodiments of the invention are described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a schematic configuration of the semiconductor gas sensor 10 of the present embodiment, FIG. 2 is an enlarged cross-sectional view of the vicinity of the surface of the oxide semiconductor layer 22, and FIG. FIG. 6 is an explanatory view showing a schematic reaction formula with a liquid 26.
　本実施形態の半導体式ガスセンサ１０は、図１に示すように、基板１２と、一対の電極１４，１６と、酸化物半導体層２２と、リンカー部２４と、イオン液体２６と、金属錯体２８とを備えている。 As shown in FIG. 1, the semiconductor gas sensor 10 according to the present embodiment includes the substrate 12, the pair of electrodes 14 and 16, the oxide semiconductor layer 22, the linker portion 24, the ionic liquid 26, and the metal complex 28. Is equipped.
　基板１２は、例えばセラミックスなどの絶縁材料で形成された板状部材である。基板１２を平面視したときの形状は、特に限定するものではなく、例えば円形であってもよいし矩形であってもよい。 The substrate 12 is a plate-like member formed of, for example, an insulating material such as ceramics. The shape of the substrate 12 in plan view is not particularly limited, and may be, for example, circular or rectangular.
　一対の電極１４，１６は、基板１２の表面に所定距離だけ離れて設けられている。一対の電極１４，１６は、例えば白金、金、銀、銅などの導電性材料で形成されている。一対の電極１４，１６を平面視したときの形状は、特に限定するものではなく、例えば櫛歯状であってもよいし矩形であってもよい。 The pair of electrodes 14 and 16 are provided on the surface of the substrate 12 so as to be separated by a predetermined distance. The pair of electrodes 14 and 16 are formed of, for example, a conductive material such as platinum, gold, silver, copper or the like. The shape of the pair of electrodes 14 and 16 in plan view is not particularly limited, and may be, for example, a comb shape or a rectangular shape.
　酸化物半導体層２２は、基板１２の表面全体を被覆しており、一対の電極１４，１６と接触している。酸化物半導体層２２の厚さは、特に限定するものではないが、例えば０．１μｍ～５μｍである。酸化物半導体層２２は、多孔体であり、図２に示すように表面に多数の孔２２ａを有している。酸化物半導体層２２は、孔２２ａを有しない場合に比べて単位体積当たりの表面積が大きい。酸化物半導体層２２の気孔率は、特に限定するものではないが、例えば１０％以上であることが好ましく、３０％以上７０％以下であることがより好ましい。孔２２ａは、開気孔であってもよいし閉気孔であってもよい。酸化物半導体層２２を構成する材料としては、半導体であれば特に限定するものではないが、例えば、酸化スズ（ＳｎＯ2）、酸化チタン（ＴｉＯ2）、酸化タングステン（ＷＯ3）、イリジウムスズ酸化物（ＩＴＯ）、亜鉛スズ酸化物（Ｚｎ2ＳｎＯ4）などが挙げられる。孔２２ａのサイズは、孔２２ａの表面にリンカー部２４及びイオン液体２６を介して金属錯体２８が固定化されるのを許容するサイズであることが好ましく、０．０１μｍ以上１０μｍ以下とするのが好ましく、０．０５μｍ以上１μｍ以下とするのがより好ましい。 The oxide semiconductor layer 22 covers the entire surface of the substrate 12 and is in contact with the pair of electrodes 14 and 16. The thickness of the oxide semiconductor layer 22 is not particularly limited, and is, for example, 0.1 μm to 5 μm. The oxide semiconductor layer 22 is a porous body, and has a large number of holes 22a on the surface as shown in FIG. The oxide semiconductor layer 22 has a large surface area per unit volume as compared to the case where the holes 22 a are not provided. The porosity of the oxide semiconductor layer 22 is not particularly limited, but is, for example, preferably 10% or more, and more preferably 30% or more and 70% or less. The holes 22a may be open pores or closed pores. The material constituting the oxide semiconductor layer 22 is not particularly limited as long as it is a semiconductor, for example, tin oxide (SnO 2), titanium oxide (TiO 2), tungsten oxide (WO 3), iridium tin oxide (ITO), zinc tin oxide (Zn 2 SnO 4 ), and the like. The size of the holes 22a is preferably a size that allows the metal complex 28 to be immobilized on the surface of the holes 22a via the linker portion 24 and the ionic liquid 26, and should be 0.01 μm to 10 μm. Preferably, it is more preferably 0.05 μm or more and 1 μm or less.
　リンカー部２４は、図２に示すように、酸化物半導体層２２の表面に第１結合部位Ｂ１で共有結合され、イオン液体２６に第２結合部位Ｂ２で共有結合されている。リンカー部２４は、第１結合部位Ｂ１と第２結合部位Ｂ２との間に中間部２４ａを備えている。中間部２４ａは、Ｃ，Ｏ，Ｓ及びＮの少なくとも１つ以上の原子を含む。中間部２４ａは、直鎖部分を有していてもよく、さらに直鎖部分に結合する形で側鎖を有していてもよく、その場合、直鎖部分を構成する原子の数は２０以下が好ましい。第１結合部位Ｂ１の具体的な結合形態は、特に限定されるものではないが、酸化物半導体層２２は表面にＯＨ基が現れているため、例えば、エーテル結合やエステル結合、シロキサン結合などが挙げられる。エーテル結合は、図３において、リンカー部２４の元となる二価性のカップリング剤２３のＺがＯＨ基の場合に、そのＯＨ基と酸化物半導体層２２の表面のＯＨ基との脱水縮合によって形成される。エステル結合は、カップリング剤２３のＺが酸ハライド、カルボン酸、エステル又はスクシニミジルエステルの場合に、そのＺと酸化物半導体層２２の表面のＯＨ基との縮合によって形成される。シロキサン結合は、カップリング剤２３のＺがアルコキシシランの場合に、そのアルコキシシランと酸化物半導体層２２の表面のＯＨ基との縮合によって形成される。第２結合部位Ｂ２の具体的な結合形態も、特に限定されるものではないが、図３において、二価性のカップリング剤２３の官能基Ｘとイオン液体２６に含まれる官能基Ｙとによって決定される。カップリング剤２３をＲ1－Ｘ、イオン液体２６をＲ2－Ｙ、両者が結合した構造をＲ1－Ｂ２－Ｒ2 と表したときの代表的な組合せ例を表１に示す。 As shown in FIG. 2, the linker portion 24 is covalently bonded to the surface of the oxide semiconductor layer 22 at the first bonding site B 1, and is covalently bonded to the ionic liquid 26 at the second bonding site B 2. The linker portion 24 includes an intermediate portion 24a between the first binding site B1 and the second binding site B2. The middle part 24a contains at least one or more atoms of C, O, S and N. The intermediate portion 24a may have a linear portion, and may further have a side chain in a form to be bonded to the linear portion, in which case the number of atoms constituting the linear portion is 20 or less Is preferred. The specific bonding form of the first bonding site B1 is not particularly limited, but since the OH group appears on the surface of the oxide semiconductor layer 22, for example, an ether bond, an ester bond, a siloxane bond, etc. It can be mentioned. The ether bond is a dehydration condensation of the OH group and the OH group on the surface of the oxide semiconductor layer 22 when Z of the divalent coupling agent 23 that is the source of the linker portion 24 in FIG. 3 is an OH group. Formed by The ester bond is formed by condensation of Z with the OH group on the surface of the oxide semiconductor layer 22 when Z of the coupling agent 23 is an acid halide, carboxylic acid, ester or succinimidyl ester. The siloxane bond is formed by condensation of the alkoxysilane and the OH group on the surface of the oxide semiconductor layer 22 when Z of the coupling agent 23 is an alkoxysilane. The specific binding form of the second binding site B2 is also not particularly limited, but in FIG. 3, the functional form X of the divalent coupling agent 23 and the functional group Y contained in the ionic liquid 26 It is determined. A typical combination example when the coupling agent 23 is represented by R 1 -X, the ionic liquid 26 is represented by R 2 -Y, and the structure in which both are linked is represented by R 1 -B2-R 2 is shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　イオン液体２６は、リンカー部２４のうち第１結合部位Ｂ１とは異なる第２結合部位Ｂ２でリンカー部２４と共有結合されている。イオン液体２６としては、金属錯体２８を固定化可能な材料を用いる。 The ionic liquid 26 is covalently bonded to the linker portion 24 at a second binding site B2 different from the first binding site B1 in the linker portion 24. As the ionic liquid 26, a material capable of immobilizing the metal complex 28 is used.
　金属錯体２８は、検出対象のガスを選択的に捕捉する性質を持ち、イオン液体２６の間に固定化されている。例えば、金属錯体２８が４配位のＣｏ錯体の場合にはホスホニウムタイプのイオン液体を用いることが好ましい。こうしたＣｏ錯体は選択的にＮＯガスを捕捉する。一例として、式（１）のイオン液体と式（２）のＣｏ錯体との組合せが挙げられる。 The metal complex 28 has a property of selectively capturing a gas to be detected, and is immobilized between the ionic liquid 26. For example, when the metal complex 28 is a four-coordinate Co complex, it is preferable to use a phosphonium type ionic liquid. These Co complexes selectively trap NO gas. An example is a combination of the ionic liquid of formula (1) and the Co complex of formula (2).
Figure JPOXMLDOC01-appb-C000002
Figure JPOXMLDOC01-appb-C000002
　金属錯体２８が６配位のＦｅ－Ｆｅ錯体（核に２つのＦｅを有する錯体）の場合にはアンモニウムタイプのイオン液体を用いることが好ましい。こうしたＦｅ－Ｆｅ錯体は選択的にＯ2ガスを捕捉する。一例として、式（３）のイオン液体と式（４）のＦｅ－Ｆｅ錯体との組合せが挙げられる。 In the case where the metal complex 28 is a hexa-coordinated Fe--Fe complex (a complex having two Fe in its core), it is preferable to use an ammonium type ionic liquid. These Fe-Fe complexes selectively trap O 2 gas. One example is the combination of the ionic liquid of formula (3) with the Fe-Fe complex of formula (4).
Figure JPOXMLDOC01-appb-C000003
Figure JPOXMLDOC01-appb-C000003
　金属錯体２８が４配位のＴｉ錯体の場合にはピロリジニウムタイプのイオン液体を用いることが好ましい。こうしたＴｉ錯体は選択的にＮ2ガスを捕捉する。一例として、１－ブチル－１－メチルピロリジニウム　トリス（ペンタフルオロエチル）トリフルオロホスフェートとＣｐ2ＴｉＣｌ2（Ｃｐはシクロペンタジエニル基）との組合せが挙げられる。 When the metal complex 28 is a tetracoordinate Ti complex, it is preferable to use a pyrrolidinium type ionic liquid. These Ti complexes selectively trap N 2 gas. One example is a combination of 1-butyl-1-methylpyrrolidinium tris (pentafluoroethyl) trifluorophosphate and Cp 2 TiCl 2 (Cp is a cyclopentadienyl group).
　金属錯体２８が６配位のＲｕ錯体の場合にはイミダゾリウムタイプのイオン液体を用いることが好ましい。こうしたＲｕ錯体は選択的にＮＨ3ガスを捕捉する。一例として、１－ブチル－３－メチルイミダゾリウム　ヘキサフルオロホスフェートとトリス（２，２’－ビピリジル）ルテニウム（II）クロリドとの組合せが挙げられる。 When the metal complex 28 is a six-coordinate Ru complex, it is preferable to use an imidazolium type ionic liquid. These Ru complexes selectively trap NH 3 gas. One example is the combination of 1-butyl-3-methylimidazolium hexafluorophosphate and tris (2,2'-bipyridyl) ruthenium (II) chloride.
　次に、半導体式ガスセンサ１０の使用例について説明する。半導体式ガスセンサ１０を使用する際には、一対の電極１４，１６を直流電源３０に接続すると共に、電流計４０を直列に接続する。そして、金属錯体２８に選択的に捕捉される特定のガスを含む混合ガスを金属錯体２８に接触させる。すると、混合ガス中の特定のガスが金属錯体２８に捕捉される。その特定のガスの濃度が変化すると、その濃度に応じて酸化物半導体層２２上の表面電位が変化し、酸化物半導体層２２に接触している一対の電極１４，１６の間を流れる電流が変化する。そのため、一対の電極１４，１６の間を流れる電流を電流計４０で測定すれば特定のガスの濃度を求めることができる。 Next, a usage example of the semiconductor gas sensor 10 will be described. When using the semiconductor gas sensor 10, the pair of electrodes 14 and 16 are connected to the DC power supply 30, and the ammeter 40 is connected in series. Then, a mixed gas containing a specific gas selectively trapped in the metal complex 28 is brought into contact with the metal complex 28. Then, a specific gas in the mixed gas is trapped by the metal complex 28. When the concentration of the specific gas changes, the surface potential on the oxide semiconductor layer 22 changes according to the concentration, and the current flowing between the pair of electrodes 14 and 16 in contact with the oxide semiconductor layer 22 Change. Therefore, if the current flowing between the pair of electrodes 14 and 16 is measured by the ammeter 40, the concentration of a specific gas can be determined.
　さらに、図１に示していないが、一対の電極１４、１６とは別に金属錯体２８の上方にゲート電極を設けることもできる。このゲート電極と電極１４、１６に電圧を印加することによって、金属錯体２８に捕捉されたガス分子を離脱させることができる。これによって金属錯体２８にはガスが捕捉されていない初期状態に戻すことができ、半導体式ガスセンサ１０を再生することが可能である。 Furthermore, although not shown in FIG. 1, a gate electrode may be provided above the metal complex 28 separately from the pair of electrodes 14 and 16. By applying a voltage to the gate electrode and the electrodes 14 and 16, gas molecules trapped in the metal complex 28 can be released. As a result, the gas can be returned to the initial state in which the gas is not trapped by the metal complex 28, and the semiconductor gas sensor 10 can be regenerated.
　以上説明した本実施形態の半導体式ガスセンサ１０によれば、混合ガスに含まれる特定（検出対象）のガスを選択的に検出できる。 According to the semiconductor type gas sensor 10 of the present embodiment described above, it is possible to selectively detect a specific (detection target) gas contained in the mixed gas.
　また、酸化物半導体層２２とイオン液体２６は、リンカー部２４にそれぞれ第１結合部位Ｂ１及び第２結合部位Ｂ２で共有結合されている。こうした共有結合は、結合力が強いため、電圧や高温に対する耐久性が高い。したがって、半導体式ガスセンサ１０は、耐久性に優れる。 The oxide semiconductor layer 22 and the ionic liquid 26 are covalently bonded to the linker portion 24 at the first bonding site B1 and the second bonding site B2, respectively. Such covalent bonds have high bonding strength and thus have high resistance to voltage and high temperature. Therefore, the semiconductor gas sensor 10 is excellent in durability.
　更に、酸化物半導体層２２は、多孔体であるため、緻密体に比べて単位体積当たりの表面積が大きい。そのため、酸化物半導体層２２に結合されるリンカー部２４、イオン液体２６及びそのイオン液体２６に固定化される金属錯体２８の量も緻密体の場合に比べて多くなり、検出可能なガス濃度範囲が広くなる。 Furthermore, since the oxide semiconductor layer 22 is a porous body, the surface area per unit volume is larger than that of a dense body. Therefore, the amount of the linker portion 24 bonded to the oxide semiconductor layer 22, the ionic liquid 26, and the amount of the metal complex 28 immobilized on the ionic liquid 26 are also larger than in the case of the dense body, and the detectable gas concentration range Becomes wider.
　更にまた、多孔体である酸化物半導体層２２の単位体積当たりの表面積を大きくすることで、検出感度をより向上させたりガスとの反応効率をより向上させたりすることができる。また、半導体式ガスセンサ１０を小型化することができる。 Furthermore, by increasing the surface area per unit volume of the porous oxide semiconductor layer 22, the detection sensitivity can be further improved, and the reaction efficiency with a gas can be further improved. In addition, the semiconductor gas sensor 10 can be miniaturized.
　なお、本発明は上述した実施形態に何ら限定されることはなく、本発明の技術的範囲に属する限り種々の態様で実施し得ることはいうまでもない。 It is needless to say that the present invention is not limited to the above-mentioned embodiment at all, and can be implemented in various modes within the technical scope of the present invention.
　例えば、上述した実施形態では、酸化物半導体層２２として多孔体を用いたが、緻密体を用いてもよい。その場合、多孔体に比べて単位体積当たりの表面積が小さくなる分、検出可能なガス濃度範囲が狭くなるが、従来品に比べて耐久性は高くなる。 For example, in the above-described embodiment, a porous body is used as the oxide semiconductor layer 22, but a dense body may be used. In such a case, the detectable gas concentration range is narrowed because the surface area per unit volume is smaller than that of the porous body, but the durability is higher than that of the conventional product.
　上述した実施形態では、リンカー部２４は、第１結合部位Ｂ１と第２結合部位Ｂ２との間に中間部２４ａを備えた構造としたが、第１結合部位Ｂ１と第２結合部位Ｂ２とが直接結合した構造であってもよい。 In the embodiment described above, the linker portion 24 has a structure including the intermediate portion 24a between the first binding site B1 and the second binding site B2, but the first binding site B1 and the second binding site B2 It may be a directly coupled structure.
　上述した実施形態では、ＮＯガス等に合った金属錯体２８の具体例を例示したが、金属錯体２８を適宜選択すればその他のガス（例えばＨ2、Ｎ2Ｏ、ＣＯ2など）についても検出可能となる。その際、適切なイオン液体を選択し、このイオン液体を介して金属錯体を電極表面に固定化することで実施可能である。 In the above embodiment, although the specific examples of the metal complex 28 that fits NO gas or the like, other gases be appropriately selected metal complex 28 (for example H 2, N 2 O, etc. CO 2) also detected It becomes possible. At that time, it can be implemented by selecting an appropriate ionic liquid and immobilizing the metal complex on the electrode surface through the ionic liquid.
　以下に、本発明の実施例について説明する。なお、以下の実施例は本発明を何ら限定するものではない。 Hereinafter, examples of the present invention will be described. The following examples do not limit the present invention at all.
［実施例１］
１．半導体式ガスセンサ
　０．３ｍｍ厚みのアルミナ基板の表面に一対の櫛型形状のＰｔ電極を厚み１μｍ形成し（電極間距離０．２ｍｍ）、電極付き基板を得た。次に、平均粒径０．３μｍの酸化スズ粉末を適量の分散剤とともに水に添加し超音波処理等によって分散させた、次に、一次粒子径が５～１０ｎｍの酸化スズゾルを添加混合し、製膜用のスラリーとした。次にスピンコートプロセスにより高速回転する電極付き基板上に成膜スラリーを滴下し、乾燥後２００～４００℃で熱処理することにより、一対のＰｔ電極を被覆する多孔質酸化スズ層を形成し、酸化スズ層被覆基板を得た。この多孔質酸化スズ層は、平均細孔径が０．１μｍ、厚みが１μｍ、単位体積当たりの表面積が約１０５ｃｍ2であった。なお、多孔質酸化スズ膜の作製にあたっては、スピンコートプロセスに限らずディッピング法、スプレー法、ドクターブレード法などを用いてもよい。 Example 1
1. Semiconductor Gas Sensor A pair of comb-shaped Pt electrodes were formed to a thickness of 1 μm on the surface of an alumina substrate having a thickness of 0.3 mm (interelectrode distance 0.2 mm) to obtain a substrate with electrodes. Next, tin oxide powder having an average particle size of 0.3 μm is added to water together with an appropriate amount of dispersant and dispersed by ultrasonication etc. Next, a tin oxide sol having a primary particle size of 5 to 10 nm is added and mixed, It was a slurry for film formation. Next, a film forming slurry is dropped on a substrate with a high speed rotation by spin coating process, dried and heat treated at 200 to 400 ° C. to form a porous tin oxide layer covering a pair of Pt electrodes, and oxidation A tin layer coated substrate was obtained. The porous tin oxide layer had an average pore diameter of 0.1 μm, a thickness of 1 μm, and a surface area per unit volume of about 105 cm 2 . In addition, in preparation of a porous tin oxide film, you may use not only a spin coat process but a dipping method, a spray method, a doctor blade method, etc.
　続いて、酸化スズ層被覆基板を、ピラニア溶液（濃硫酸：３０％、過酸化水素水を３：１で混合）に２時間浸漬させた後に純水、メタノールで洗浄し、窒素ガスを吹き付けて速やかに乾燥させた。 Subsequently, the tin oxide layer-coated substrate is immersed in a piranha solution (concentrated sulfuric acid: 30%, mixed with hydrogen peroxide 3: 1) for 2 hours, washed with pure water and methanol, and sprayed with nitrogen gas. It dried quickly.
　次に、乾燥後の酸化スズ層被覆基板を、シランカップリング剤を混合したトルエン溶液（７０℃）に３時間程度浸漬させた。シランカップリング剤には信越化学工業製３－グリシドキシプロピルトリメトキシシラン（ＫＢＭ－４０３）を用いた。浸漬後、クロロホルム、水、メタノールで洗い流し、窒素ガスを吹き付けて速やかに乾燥させた。これにより、酸化スズ層被覆基板の表面に３－グリシドキシプロピルがシロキサン結合により固定化された。 Next, the dried tin oxide layer-coated substrate was immersed in a toluene solution (70 ° C.) mixed with a silane coupling agent for about 3 hours. As a silane coupling agent, 3-glycidoxypropyltrimethoxysilane (KBM-403) manufactured by Shin-Etsu Chemical Co., Ltd. was used. After immersion, the resultant was rinsed with chloroform, water and methanol, and was quickly dried by blowing nitrogen gas. Thereby, 3-glycidoxypropyl was immobilized by siloxane bond on the surface of the tin oxide layer coated substrate.
　さらに、公知文献（Chemistry Letters, Vol.45, No.4, 2016, p.436-438）に記載のホスホニウムタイプのイオン液体であるビス［１２－（トリヘキシルホスホニウム）ドデシル］ジスルファン　ビス（トリフルオロメタンスルホネート）のジスルフィド基をアミノ基に変えた式（１）のイオン液体を溶かしたエタノール溶液中に、３－グリシドキシプロピルがシロキサン結合された酸化スズ層被膜基板を２時間浸漬した。これにより、イオン液体のアミノ基とグリシドとのエポキシ開環反応により、イオン液体のアミノ基がリンカー部（－ＣＨ2ＣＨ（ＯＨ）ＣＨ2ＯＣ3Ｈ6 ＳｉＯ－、但しＳｉはシロキサン結合を形成している）を介して酸化スズ層被膜基板に固定された。その後、過剰のイオン液体を除くため、エタノール、クロロホルムで洗浄した。 Furthermore, bis [12- (trihexylphosphonium) dodecyl] disulfane bis (trifluoromethane), which is a phosphonium type ionic liquid described in known literature (Chemistry Letters, Vol. 45, No. 4, 2016, p. 436-438) In an ethanol solution in which the ionic liquid of the formula (1) in which the disulfide group of the sulfonate was changed to an amino group was dissolved, the substrate coated with tin oxide layer coated with 3-glycidoxypropyl was bonded for 2 hours. Thus, the amino group of the ionic liquid forms a linker (-CH 2 CH (OH) CH 2 OC 3 H 6 SiO-, where Si is a siloxane bond) by the epoxy ring-opening reaction of the amino group of the ionic liquid with glycide. ) Is fixed to the tin oxide layer coated substrate. After that, it was washed with ethanol and chloroform to remove excess ionic liquid.
　最後に、Ｃｏ錯体を溶解させた水溶液中に上述のイオン液体結合基板を１週間浸漬した後、過剰のＣｏ錯体を除くため、ジメチルホルムアミド、アセトニトリル、純水で洗浄した。これにより、イオン液体にＣｏ錯体が固定化されたＮＯ応答性の半導体式ガスセンサを得た。実施例１の酸化スズ層（酸化物半導体層２２）の表面を模式的に示した説明図を図４に示す。なお、図４の符号は上述した実施形態で用いた符号と同じである。 Finally, the above-mentioned ionic liquid-bonded substrate was immersed for 1 week in an aqueous solution in which a Co complex was dissolved, and then washed with dimethylformamide, acetonitrile, and pure water to remove excess Co complex. As a result, a NO-responsive semiconductor type gas sensor in which a Co complex is immobilized on an ionic liquid was obtained. An explanatory view schematically showing the surface of the tin oxide layer (oxide semiconductor layer 22) of Example 1 is shown in FIG. In addition, the code | symbol of FIG. 4 is the same as the code | symbol used in embodiment mentioned above.
２．ＮＯガス検出感度
　実施例１の半導体式ガスセンサを用いてＮＯ検出を行った。ＮＯガスは、ＪＣＳＳ（Japan Calibration Service System）に基づく標準ガスを使用した。ＮＯガスは、窒素ガスで希釈した０．５ｖｏｌｐｐｍ、１ｖｏｌｐｐｍ、５ｖｏｌｐｐｍ、１０ｖｏｌｐｐｍ、１００ｖｏｌｐｐｍを用意した。また、０．５ｖｏｌｐｐｍを窒素でさらに希釈して１００ｖｏｌｐｐｂのガスも準備した。各ガスについて、本半導体式ガスセンサから出力される電流値をモニターした結果、ＮＯ濃度が１００ｖｏｌｐｐｂで電流値が５μＡ、０．５ｖｏｌｐｐｍで２５μＡ、１ｖｏｌｐｐｍで電流値が５０μＡ、５ｖｏｌｐｐｍで電流値が２５０μＡ、１０ｖｏｌｐｐｍで電流値が５００μＡ、１００ｖｏｌｐｐｍで電流値が５ｍＡとなることを確認し、濃度の増加に伴ない、電流値は直線的に大きくなることがわかった。 2. NO Gas Detection Sensitivity NO was detected using the semiconductor gas sensor of Example 1. As NO gas, a standard gas based on JCSS (Japan Calibration Service System) was used. As the NO gas, 0.5 vol ppm, 1 vol ppm, 5 vol ppm, 10 vol ppm and 100 vol ppm diluted with nitrogen gas were prepared. In addition, 0.5 vol ppm was further diluted with nitrogen to prepare 100 vol ppb gas. As a result of monitoring the current value output from this semiconductor type gas sensor for each gas, the NO value is 100 volppb, the current value is 5 μA, 0.5 vol ppm, 25 μA, the current value is 50 μA, 1 vol ppm, the current value is 250 μA, 10 vol ppm It was confirmed that the current value was 500 μA and 100 vol ppm and the current value was 5 mA, and it was found that the current value linearly increased as the concentration increased.
　本発明は、ガスセンサに利用可能である。 The present invention is applicable to gas sensors.
１０　半導体式ガスセンサ、１２　基板、１４，１６　電極、２２　酸化物半導体層、２２ａ　孔、２３　カップリング剤、２４　リンカー部、２４ａ　中間部、２６　イオン液体、２８　金属錯体、３０　直流電源、４０　電流計、Ｂ１　第１結合部位、Ｂ２　第２結合部位。 DESCRIPTION OF SYMBOLS 10 semiconductor type gas sensor, 12 board | substrates, 14 and 16 electrodes, 22 oxide semiconductor layer, 22a hole, 23 coupling agent, 24 linker part, 24a middle part, 26 ionic liquid, 28 metal complex, 30 direct current power supply, 40 ammeter , B1 first binding site, B2 second binding site.

Claims (4)

  1. 　基板の表面に設けられた一対の電極と、
    　前記一対の電極と接触するように設けられた酸化物半導体層と、
    　前記酸化物半導体層の表面に第１結合部位で共有結合するリンカー部と、
    　前記リンカー部のうち前記第１結合部位とは異なる第２結合部位で前記リンカー部と共有結合するイオン液体と、
    　特定のガスを選択的に捕捉する性質を持ち、前記イオン液体を介して固定化された金属錯体と、
    　を備えた半導体式ガスセンサ。     A pair of electrodes provided on the surface of the substrate;
    An oxide semiconductor layer provided to be in contact with the pair of electrodes;
    A linker moiety covalently bonded to the surface of the oxide semiconductor layer at a first binding site;
    An ionic liquid covalently bonded to the linker moiety at a second binding site different from the first binding site in the linker moiety;
    A metal complex which has the property of selectively trapping a specific gas, and which is immobilized via the ionic liquid,
    Semiconductor gas sensor equipped with
  2. 　前記酸化物半導体層は、多孔体である、
    　請求項１に記載の半導体式ガスセンサ。     The oxide semiconductor layer is a porous body.
    The semiconductor gas sensor according to claim 1.
  3. 　前記酸化物半導体層は、酸化スズ、酸化チタン、酸化タングステン、イリジウムスズ酸化物又は亜鉛スズ酸化物の層である、
    　請求項１又は２に記載の半導体式ガスセンサ。     The oxide semiconductor layer is a layer of tin oxide, titanium oxide, tungsten oxide, iridium tin oxide or zinc tin oxide,
    The semiconductor type gas sensor according to claim 1 or 2.
  4. 　前記イオン液体と前記金属錯体との組合せは、ホスホニウムタイプのイオン液体と４配位のＣｏ錯体との組合せであるか、アンモニウムタイプのイオン液体と６配位のＦｅ－Ｆｅ錯体との組合せであるか、ピロリジニウムタイプのイオン液体と４配位のＴｉ錯体との組合せであるか、又は、イミダゾリウムタイプのイオン液体と６配位のＲｕ錯体との組合せである、
    　請求項１～３のいずれか１項に記載の半導体式ガスセンサ。     The combination of the ionic liquid and the metal complex is a combination of a phosphonium type ionic liquid and a tetracoordinated Co complex, or a combination of an ammonium type ionic liquid and a hexacoordinated Fe-Fe complex Or a combination of a pyrrolidinium type ionic liquid and a tetracoordinated Ti complex, or a combination of an imidazolium type ionic liquid and a hexacoordinated Ru complex,
    The semiconductor gas sensor according to any one of claims 1 to 3.
PCT/JP2017/024987 2017-07-07 2017-07-07 Semiconductor-type gas sensor WO2019008749A1 (en)

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