WO2017026785A1 - Complexe pour détection de gaz hautement fiable sans l'influence de l'humidité, procédé pour sa fabrication, capteur de gaz comprenant le complexe pour la détection de gaz, et son procédé de fabrication - Google Patents

Complexe pour détection de gaz hautement fiable sans l'influence de l'humidité, procédé pour sa fabrication, capteur de gaz comprenant le complexe pour la détection de gaz, et son procédé de fabrication Download PDF

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WO2017026785A1
WO2017026785A1 PCT/KR2016/008770 KR2016008770W WO2017026785A1 WO 2017026785 A1 WO2017026785 A1 WO 2017026785A1 KR 2016008770 W KR2016008770 W KR 2016008770W WO 2017026785 A1 WO2017026785 A1 WO 2017026785A1
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gas
salt
group
mixtures
ceo
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Korean (ko)
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이종흔
윤지욱
김준식
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고려대학교 산학협력단
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Priority claimed from KR1020150112273A external-priority patent/KR101594734B1/ko
Priority claimed from KR1020160098788A external-priority patent/KR20180015369A/ko
Application filed by 고려대학교 산학협력단 filed Critical 고려대학교 산학협력단
Priority to US15/751,679 priority Critical patent/US11221306B2/en
Publication of WO2017026785A1 publication Critical patent/WO2017026785A1/fr

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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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
    • G01N33/483—Physical analysis of biological material
    • G01N33/497—Physical analysis of biological material of gaseous biological material, e.g. breath
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F17/00—Compounds of rare earth metals
    • C01F17/20—Compounds containing only rare earth metals as the metal element
    • C01F17/206—Compounds containing only rare earth metals as the metal element oxide or hydroxide being the only anion
    • C01F17/224—Oxides or hydroxides of lanthanides
    • C01F17/235—Cerium oxides or hydroxides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G15/00—Compounds of gallium, indium or thallium
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G19/00—Compounds of tin
    • C01G19/02—Oxides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G41/00—Compounds of tungsten
    • C01G41/02—Oxides; Hydroxides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/04—Oxides; Hydroxides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G9/00—Compounds of zinc
    • C01G9/02—Oxides; Hydroxides
    • 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
    • G01N27/125—Composition of the body, e.g. the composition of its sensitive layer
    • G01N27/127—Composition of the body, e.g. the composition of its sensitive layer comprising nanoparticles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y15/00—Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
    • G01N33/0036—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
    • G01N33/0059—Avoiding interference of a gas with the gas to be measured
    • G01N33/006—Avoiding interference of water vapour with the gas to be measured

Definitions

  • the present invention relates to a gas detection composite having a stable and reliable detection capability in a humid environment, a method for manufacturing the same, a gas sensor including the gas detection composite as a gas sensitive layer, and a method for manufacturing the same.
  • the oxide semiconductor gas sensor Since the oxide semiconductor gas sensor was first proposed in the 1960s by Prof. Seiyama of Kyushu University, Japan, it has been developed for driver drinking measurement, explosive gas detection and exhaust gas due to its advantages of high sensitivity, compact integration, simple operation circuit and low price. It has been widely used in the field of detection and detection of harmful gas. In addition, as interest in human health and environmental pollution has recently increased, the demand for indoor and outdoor environmental gas detection sensors, self-diagnosis gas sensors for diseases, and artificial olfactory sensors that can be mounted on mobile devices has been rapidly increasing. However, the oxide semiconductor type gas sensor has a fundamental problem in that it easily reacts with external moisture and degrades performance and reliability. Therefore, it is still difficult to commercialize.
  • An oxide semiconductor gas sensor detects gas through a resistance change that occurs when a reducing gas reacts with oxygen ions adsorbed on an oxide surface.
  • the oxygen ions on the oxide surface are similar to the test gas. Is consumed first, so the gas sensitivity is greatly reduced and the sensor resistance is changed.
  • oxide semiconductor type gas sensor operates in the air, exposure to moisture is inevitable, and humidity changes very much due to weather, season, day and night changes, so stable gas response characteristics without solving humidity dependence of sensor It is almost impossible to secure.
  • the humidity in the atmosphere is generally thousands of tens of thousands of ppm, which is very high compared to the general concentration (several tens of ppm) of the gas to be measured by the gas sensor.
  • the present inventors also recognize the above-described problems, and in order to provide a gas sensor capable of exhibiting ultra-high sensitivity, high selectivity and high-speed response characteristics without the influence of moisture on various reducing gases, indium hollow structure and cerium oxide It has been reported about the gas detection complex containing a nanoparticle, its manufacturing method, etc. (patent document 1).
  • Patent Document 1 Republic of Korea Patent Publication No. 10-1594734
  • Non-Patent Document 1 H.-R. Kim, Adv. Funct. Mater. 21 (2011) 4456-4463
  • the gas sensitivity and sensor resistance can be derived constantly within a very fast time
  • the present invention provides a highly reliable gas detection composite, a manufacturing method thereof, a gas sensor including the gas detection composite as a gas sensitive layer, and a manufacturing method thereof.
  • the present invention to solve the first problem
  • Nanostructures of oxide semiconductors selected from the group consisting of SnO 2 , ZnO, WO 3 , NiO and In 2 O 3 ;
  • It provides a gas detection complex comprising a CeO 2 additive supported on the nanostructures.
  • the nanostructure may be a nanostructure having a hollow structure or an egg yolk structure.
  • the CeO 2 additive may be applied to the surface of the nanostructures.
  • the CeO 2 additive may be supported in an amount of 3 wt% to 30 wt% based on the total weight of the gas sensor.
  • the gas may be a reducing gas selected from the group consisting of acetone, formaldehyde, ethanol, carbon monoxide, xylene, toluene, benzene and mixtures thereof.
  • the Sn salt is SnC 2 O 4, SnCl 4 ⁇ xH 2 O (x 2 or 5), Sn (CH 3 COO ) 4 And mixtures thereof;
  • the Zn salt is selected from the group consisting of Zn (NO 3 ) 2 .6H 2 O, ZnCl 2 , Zn (CH 3 COO) 2 .2H 2 O and mixtures thereof;
  • the W salt is selected from the group consisting of WO 3 , (NH 4 ) 10 H 2 (W 2 O 7 ) 6 and mixtures thereof;
  • the Ni salt is selected from the group consisting of Ni (NO 3 ) 2 .6H 2 O, NiCl 2 .6H 2 O, Ni (CH 3 COO) 2 .4H 2 O, and mixtures thereof;
  • the Ce salt is selected from the group consisting of Ce (NO 3
  • the spray pyrolysis reaction of step b) is by spraying the solution into the furnace heated to 600 ° C to 1100 ° C at an injection rate of 2 L / m to 50 L / m Can be performed.
  • the Sn salt is SnC 2 O 4, SnCl 4 ⁇ xH 2 O (x 2 or 5), Sn (CH 3 COO ) 4 And mixtures thereof;
  • the Zn salt is selected from the group consisting of Zn (NO 3 ) 2 .6H 2 O, ZnCl 2 , Zn (CH 3 COO) 2 .2H 2 O and mixtures thereof;
  • the W salt is selected from the group consisting of WO 3 , (NH 4 ) 10 H 2 (W 2 O 7 ) 6 and mixtures thereof;
  • the Ni salt is selected from the group consisting of Ni (NO 3 ) 2 .6H 2 O, NiCl 2 .6H 2 O, Ni (CH 3 COO) 2 .4H 2 O, and mixtures thereof;
  • the Ce salt may be selected from the group consisting of Ce (NO 3
  • the reduction reaction of step b) may be carried out by adding a substance selected from the group consisting of NaBH 4 , hydrazine and mixtures thereof as the reducing agent.
  • the present invention also provides a gas detection gas sensor comprising the gas detection complex as a gas sensitive layer.
  • It provides a method of manufacturing a gas sensor comprising the step of coating, drying and heat treatment the solution on a substrate.
  • the coating is carried out by a drop-coating process, the drying is performed for 12 to 24 hours at 70 °C to 120 °C, the heat treatment for 1 hour at 500 °C to 900 °C To 6 hours.
  • an oxide semiconductor nanostructure in which CeO 2 is uniformly added a gas detection complex capable of rapid detection with high sensitivity with respect to a gas to be detected regardless of the presence and concentration of moisture, and a method of manufacturing the same
  • the present invention may provide a gas sensor including the gas detecting complex as a gas sensitive layer and a method of manufacturing the same.
  • FIG. 1 is a schematic process diagram of a method for manufacturing a hollow gas sensor according to Examples 1-1 and 1-2 using ultrasonic spray pyrolysis.
  • FIG. 2 is a schematic process diagram of a method for manufacturing a yolk structure gas sensor according to Examples 2-1 and 2-2 using ultrasonic spray pyrolysis.
  • Example 3 is a schematic process diagram of a method of manufacturing a gas sensor according to Example 3 using a solution stirring method.
  • Example 5 is a SEM photograph of Example 3 (b) and commercial SnO 2 fine powder (Comparative Example 3) (a) synthesized using a solution stirring method.
  • Example 6 shows Example 1-1, Comparative Example 1-1, Example 1-2, Comparative Example 1-2, Example 2-1, Comparative Example 2-1, Example 2-2 and Comparative Example using XRD. Phase analysis results for 2-2.
  • Example 7 shows phase analysis results of Example 3 and Comparative Example 3 using XRD.
  • FIG. 8 is a comparison result of 20 ppm acetone gas sensitive transient and gas sensitivity in the dry atmosphere and the relative humidity 80% atmosphere measured at 450 ° C.
  • FIG. 8 is a comparison result of 20 ppm acetone gas sensitive transient and gas sensitivity in the dry atmosphere and the relative humidity 80% atmosphere measured at 450 ° C.
  • Example 9 shows Comparative Example 1-1, Example 1-1, Comparative Example 1-2, Example 1-2, Comparative Example 2-1, Example 2-1, Comparative Example 2-2, and the like measured at 450 ° C. It is the result of 20 ppm acetone gas sensitivity in the dry atmosphere of Example 2-2, and 20, 50, 80% of relative humidity atmosphere.
  • Example 10 is Comparative Example 1-1, Example 1-1, Comparative Example 1-2, Example 1-2, Comparative Example 2-1, Example 2-1, Comparative Example 2-2, and the result measured at 450 ° C. It is the result of sensor resistance comparison in the dry atmosphere and relative humidity of 20, 50, 80% of Example 2-2.
  • FIG. 11 is a result of comparing acetone gas sensitivity and sensor resistance of 20 ppm in a dry atmosphere, a relative humidity of 20, 50, and 80% atmosphere of the gas sensors according to Comparative Examples 3 and 3 measured at 450 ° C.
  • FIG. 12 is a schematic diagram of a process for manufacturing a gas detection complex using a layer-by-layer process according to an embodiment of the present invention.
  • FIG. 13 is a schematic diagram of a process for manufacturing a gas detection complex using a single process according to another embodiment of the present invention.
  • Example 14A-14I show pure In 2 O 3 hollow structure (Comparative Example 4), and 1.04 wt% (Comparative Example 5-1), 2.33 wt% (Comparative Example 5-2), 4.97 wt% (Example 4-2 ), 11.7 wt% (Example 4-1), 22.4 wt% (Example 4-3), 39.9 wt% (Example 4-4), 45.6 wt% (Comparative Example 5-3) and 55.0 wt% ( CeO 2 of Comparative Example 5-4 SEM photographs of fine powder with nanoparticles uniformly coated on the In 2 O 3 hollow structure surface.
  • FIGS. 15A-15G are TEM photographs of fine powders according to Comparative Example 4 (FIGS. 15A-15C) and Example 4-1 (FIGS. 15D-15G).
  • 16A-16H are TEM photographs of fine powders according to Examples 4-3 (FIGS. 16A-16D) and Examples 4-4 (FIGS. 16E-16H).
  • 17A to 17D are SEM and TEM images of fine powders according to Example 5.
  • FIG. 17A to 17D are SEM and TEM images of fine powders according to Example 5.
  • Example 20 is a sensor resistance change and acetone 20 ppm, ethanol 20 ppm, hydrogen 200 ppm, in a dry atmosphere and a relative humidity of 80% at a temperature of 450 °C of Example 4-1 (Fig. 20a), Comparative Example 4 (Fig. 20b) Sensitivity change for 200 ppm of carbon monoxide, 200 ppm of hydrogen, 100 ppm of toluene, 200 ppm of ammonia and 50 ppm of formaldehyde.
  • 21A to 21D illustrate the response temperatures of fine powders according to Comparative Example 4, Comparative Example 5-1, Comparative Example 5-2, Example 4-2, Example 4-1, Example 4-3 and Example 4-4.
  • Gas sensitivity (21a), sensor resistance (21b), gas sensitivity with moisture (21c) and sensor resistance rate of change for acetone at 20 ppm in a dry atmosphere, 20%, 50% and 80% relative humidity at 450 ° C. 21d) is a graph.
  • 22A and 22B illustrate a dry atmosphere of fine powders according to Comparative Example 4, Comparative Example 5-1, Comparative Example 5-2, Example 4-2, Example 4-1, Example 4-3 and Example 4-4. , 90% gas reaction time (22a) and 90% recovery time (22b) for 20 ppm acetone in 20%, 50%, 80% relative humidity.
  • 23A and 23B are graphs showing 20 ppm of acetone gas sensitive transient and gas sensitivity in a dry atmosphere and a relative humidity of 80% of the fine powder according to Comparative Example 4 and Example 4-1.
  • 24A and 24B show the sensor resistance and gas sensitivity according to the gas sensitive transient and the number of measurements for 20 ppm acetone in the relative humidity 20%, 50% and 80% atmosphere of the fine powders according to Comparative Examples 4 and 4-1. It is a graph showing the change.
  • 25A and 25B are graphs illustrating gas sensitivity and selectivity in an atmosphere of 80% drying and relative humidity of fine powders according to Comparative Example 4 and Example 4-1.
  • 26A and 26B are graphs illustrating transient and gas sensitivity of acetone gas concentrations in an atmosphere of 80% drying and relative humidity of fine powder according to Example 4-1.
  • FIG. 27 is a graph showing a gas sensitive transient of 20 ppm acetone of fine powders according to Example 5.
  • the present invention provides a gas detection complex based on an oxide semiconductor nanostructure to which CeO 2 is uniformly added.
  • the oxide semiconductor nanostructure serves as a main gas sensitive body for the detection gas, and the added CeO 2 serves to selectively absorb and remove moisture introduced from the outside.
  • CeO 2 is an ion conductor that delivers lattice oxygen and oxygen ions at very high speed through excellent valence conversion ability.It is reported that CeO 2 can play a role of removing hydroxyl groups formed on the surface of PEM after long time driving in PEMFC field. There is a bar (V. Prabhakaran, PNAS (2012) 109, 1029-1034). Therefore, in the present invention, when the CeO 2 nanoparticles are applied to the surface of the gas sensitive body, it was determined that the reverse reaction of Reaction Scheme 1, which is a moisture adsorption reaction, may be induced, and the humidity dependence of the sensor actually decreased to a negligible level. .
  • CeO 2 nanoparticles are determined to remove the humidity dependency according to the reaction schemes described below.
  • Ce 4 + in CeO 2 nanoparticles is converted to Ce 3 + by reaction with moisture to generate hydrogen ions and oxygen (Scheme 2).
  • Ce 3 + and hydrogen ions are reacted with a hydroxyl group formed on the surface of the gas sensitive body through Scheme 3, Ce 3 + is oxidized to Ce 4 + and water is generated and desorbed (Scheme 4).
  • the oxygen generated in Scheme 2 is reacted with electrons injected into the surface of the gas sensitive body in Scheme 3 and regenerated into oxygen ions (Scheme 5).
  • Nanoparticles protect oxide semiconductor nanostructures such as SnO 2 , ZnO, WO 3 , NiO, and In 2 O 3, which are the main sensitive materials, from a large amount of moisture constantly supplied from the outside, thereby minimizing or eliminating the humidity dependency of the sensor. Will perform. Since this reaction occurs only at the interface area between the interface between CeO 2 and the gas sensitive body, more than a certain amount of CeO 2 nanoparticles must be applied to the gas sensitive surface to protect most of the gas sensitive surface from moisture. However, when excess CeO 2 is applied, CeO 2 The nanoparticles may be connected to each other to change the resistance of the sensor, or may interfere with conduction through the gas sensitive body. Therefore, in order to remove externally supplied moisture effectively while CeO 2 has a minimal effect on the resistance change of the sensor and the gas response, it is essential that an appropriate concentration of CeO 2 is discontinuously and uniformly in most of the gas sensitive body. to be.
  • Nanostructures of oxide semiconductors selected from the group consisting of SnO 2 , ZnO, WO 3 , NiO and In 2 O 3 ;
  • It provides a gas detection complex comprising a CeO 2 additive supported on the nanostructures.
  • the nanostructure may be a nanostructure having a hollow structure or a yolk structure, as will be described later, when using a SnO 2 , ZnO, or In 2 O 3 oxide semiconductor, the hollow structure is a WO 3 or NiO oxide semiconductor When used, an egg yolk structure can be produced.
  • CeO 2 additive may be applied to the surface of the nanostructures in order to effectively protect from moisture and minimize the impact on gas sensitive reactions.
  • the CeO 2 additive may be supported in an amount of 3 wt% to 30 wt% based on the total weight of the gas sensor.
  • the CeO 2 additive is less than 3 wt%, the effect of protecting the gas sensitive body from moisture is insignificant.
  • the gas detection complex according to the present invention is used for the detection of various reducing gases selected from the group consisting of various volatile organic compound gases including acetone, formaldehyde, ethanol, carbon monoxide, xylene, toluene, benzene, and mixtures thereof. This is possible.
  • the present invention provides a method for producing the gas detection complex, the method according to the present invention,
  • the Sn salt may be selected from SnC 2 O 4 , SnCl 4 xH 2 O (x is 2 or 5), and Sn (CH 3 COO) 4 And mixtures thereof;
  • the Zn salt is selected from the group consisting of Zn (NO 3 ) 2 .6H 2 O, ZnCl 2 , Zn (CH 3 COO) 2 .2H 2 O and mixtures thereof;
  • the W salt is selected from the group consisting of WO 3 , (NH 4 ) 10 H 2 (W 2 O 7 ) 6 and mixtures thereof;
  • the Ni salt is selected from the group consisting of Ni (NO 3 ) 2 .6H 2 O, NiCl 2 .6H 2 O, Ni (CH 3 COO) 2 .4H 2 O, and mixtures thereof;
  • the Ce salt is selected from the group consisting of Ce
  • an organic acid or sugar is added to the solution of step a), and the organic acid is citric acid, ethylene It may be selected from the group consisting of glycols and mixtures thereof.
  • the sugar when CeO 2 is added to the nanostructure having an egg yolk structure using the W salt or the Ni salt, the sugar may be selected from the group consisting of sucrose, glucose and mixtures thereof.
  • the spray pyrolysis reaction may be carried out under the conditions of spraying the solution prepared in step a) into the furnace heated at 600 °C to 1100 °C at a spray rate of 2 L / m to 50 L / m. .
  • gas detection composite according to the present invention can also be produced by the above-described spray pyrolysis reaction, but in some cases it can also be produced by the liquid stirring method, the method according to the liquid stirring method,
  • the Sn salt, the Zn salt, the W salt, the Ni salt, the In salt and the Ce salt are the same as described in the spray pyrolysis reaction.
  • the step of reducing the mixed solution should be carried out in order to prepare the nanostructure added with CeO 2 , wherein as the reducing agent, a material selected from the group consisting of NaBH 4 , hydrazine and mixtures thereof may be used. Can be.
  • the gas detection complex according to the present invention can also be produced by a layer-by-layer process, the manufacturing method according to another embodiment of the present invention,
  • a solution including an In salt and a sugar is prepared (S1), and the solution is first spray pyrolyzed to obtain a hollow structure.
  • the resultant is mixed with a solution of the surface charge modifier to introduce a charge to the surface of the hollow structure of the In 2 O 3 main sensitizer ( S3).
  • the charge introduction process may include sequentially adding a surface positive charge modifier and a surface negative charge modifier, and the surface positive charge modifier may include polyethyleneimine, poly (allylamine hydrochloride), and poly (diallyldimethylammonium chloride). And the mixture may be selected from the group consisting of, and the surface negative charge modifier may be selected from the group consisting of polyacrylic acid, poly (styrenesulfonate), poly (vinylsulfonate) and mixtures thereof.
  • the reducing agent may be selected from the group consisting of sodium borohydride, hydrazine and mixtures thereof.
  • the present invention provides a gas sensor for gas detection comprising the gas detection complex as a gas sensitive layer, the gas sensor,
  • the solution is preparable by coating, drying and heat treating a substrate.
  • the coating is performed by a drop-coating process
  • the drying is performed for 12 to 24 hours at 70 °C to 120 °C
  • the heat treatment may be performed for 1 hour to 6 hours at 500 °C to 900 °C have.
  • Acetone is a indoor and outdoor environmental pollutant gas and at the same time it is a biomarker gas detected in the exhalation of a person suffering from diabetes, it is a very important problem to selectively detect it regardless of the presence and concentration of moisture. Therefore, in the following examples, acetone was selected as the main measurement gas, and the influence of external moisture on gas sensitivity and sensor resistance of the sensor was analyzed.
  • pure SnO 2 hollow fine powder (Comparative Example 1-1), pure ZnO hollow fine powder (Comparative Example 1-2), pure WO 3 egg yolk structure fine powder (Comparative Example 2-1), and pure NiO (Comparative Example) 2-2)
  • a gas sensor according to a comparative example was manufactured using an egg yolk structure fine powder.
  • the hollow structure of 3 SnO 2 wt% CeO 2 is added (Example 1-1)
  • ZnO hollow structure of the 5 wt% CeO 2 is added (Example 1-2)
  • 12 wt% CeO 2 is The added WO 3 egg yolk structure (Example 2-1)
  • NiO egg yolk structure (Example 2-2) to which 30 wt% of CeO 2 was added were synthesized by ultrasonic spray pyrolysis, and then gas was used.
  • the sensor was produced. For the gas sensors manufactured as described above, the humidity dependence, gas sensitivity, sensor resistance, and the like of the sensors were compared.
  • a gas sensor (Example 3) was fabricated using SnO 2 hollow fine powder containing 3 wt% of CeO 2 nanoparticles prepared by liquid phase agitation, and the difference in humidity dependence and gas response characteristics according to the synthesis method was investigated. Evaluated. 1 to 3, respectively, using the ultrasonic spray pyrolysis method, a process diagram (FIG. 1) for manufacturing a hollow structure gas sensor according to Example 1-1 and Example 1-2, using the ultrasonic spray pyrolysis method Process diagram (Fig. 2) for the method for manufacturing the yolk structure gas sensor according to Example 2-1 and Example 2-2, and for the method for manufacturing the gas sensor according to Example 3 using the solution stirring method Process diagrams (FIG. 3) are respectively shown.
  • pure In 2 O 3 hollow fine powder (Comparative Example 4) and 1.04% by weight (Comparative Example 5-1), 2.33% by weight (Comparative Example 5-2), 4.97% by weight (Example 4- 2), 11.7 wt% (Example 4-1), 22.4 wt% (Example 4-3), 39.9 wt% (Example 4-4), 45.6 wt% (Comparative Example 5-3), 55.0 wt%
  • the gas sensor coated with CeO 2 nanoparticles of (Comparative Example 5-4) is uniformly coated on the surface of In 2 O 3 hollow structure, and the sensor's humidity dependence, gas sensitivity, sensor resistance, reaction / recovery rate, and acetone selectivity And the like.
  • the gas sensor is manufactured according to the process of omitting the surface modification process of the fine powder described in Example 4, wherein 5.7% by weight (Example 5) of CeO 2 nanoparticles is uniformly coated on the In 2 O 3 hollow structure surface Also produced.
  • the synthesized fine powder was mixed with tertiary distilled water and drop-coated on the alumina substrate on which the Au electrode was formed, and heat-treated at 500 ° C. for 2 hours to prepare a gas sensor.
  • the sensor was fabricated at 450 ° C., i) air in a dry atmosphere, ii) air in a 20, 50, 80% relative humidity atmosphere, iii) air in a dry atmosphere + 20 ppm acetone, and iv) 20, 50, 80% relative
  • the change in resistance was measured by injecting alternating air + 20 ppm acetone in a humidity atmosphere. Acetone was premixed and then rapidly changed in concentration using a 4-way valve. The total flow rate was fixed at 100 SCCM so that the temperature difference did not occur when the gas concentration changed.
  • Zinc nitrate hexahydrate Zn (NO 3 ) 2 6H 2 O, 99.0%, Sigma-Aldrich, USA
  • Citric acid monohydrate HOC (COOH) (CH 2 COOH) in 600 mL of tertiary distilled water ) 2 ⁇ H 2 O, 99.0%, Sigma-Aldrich, USA
  • HOC Citric acid monohydrate
  • Calculate the weight ratio of Ce / Zn to 5/95 to the prepared spray solution add Ce nitrate hexahydrate (Ce (NO 3 ) 3 ⁇ 6H 2 O, 99.99%, Sigma-Aldrich, USA) and stir for 5 minutes. Then ultrasonically sprayed.
  • micro-sized droplets formed by ultrasonic wave were immediately heat-treated at a flow rate of (O 2 ) 900 ° C. at a flow rate of 10 L ⁇ min ⁇ 1 to synthesize ZnO hollow structures uniformly added with 5 wt% CeO 2.
  • Example 1-2 Pure ZnO hollow structure without CeO 2 was synthesized through the same process without adding Ce source (Comparative Example 1-2). Fabrication of the gas sensor was performed in the same manner as in Example 1-1.
  • Example 2-1 After stirring, it was ultrasonically sprayed. Droplets of microscopic formed through the ultrasound at a flow rate of 5 L ⁇ are min -1 (O 2) while passing through the to the 900 °C the reaction of a 12 wt% CeO 2 WO 3 yolk structure are uniformly added to the heat treated immediately It synthesize
  • Nickel nitrate hexahydrate Ni (NO 3 ) 2 .6H 2 O, 99.999%, Sigma-Aldrich, USA
  • 0.7 M Sucrose C 12 H 22 O 11 , 99.5%, in 600 mL tertiary distilled water
  • Sigma-Aldrich, USA was added and stirred for 30 minutes to prepare a spray solution.
  • Ce nitrate hexahydrate Ce (NO 3 ) 3 ⁇ 6H 2 O, 99.99%, Sigma-Aldrich, USA
  • micro-sized droplets formed by ultrasonic wave were immediately heat-treated at a flow rate of (O 2 ) 900 ° C. at a flow rate of 5 L ⁇ min ⁇ 1 to synthesize NiO egg yolk structure in which 30 wt% of CeO 2 was uniformly added.
  • Example 2-2 Pure NiO egg yolk structure without CeO 2 was synthesized through the same process without adding Ce source (Comparative Example 2-2). Fabrication of the gas sensor was performed in the same manner as in Example 1-1.
  • Example 3 In the case of pure SnO 2 fine powder, commercial SnO 2 fine powder was obtained by heat treatment at 500 ° C. for 3 hours without additional synthesis (Comparative Example 3). Fabrication of the gas sensor was performed in the same manner as in Example 1-1.
  • Example 1-1, Example 1-2, Example 2-1, Example 3, Comparative Example 1-1, comparison Example 1-2, Comparative Example 2-1, and Comparative Example 3 exhibited a high resistance state in air, but showed an n-type semiconductor characteristic in which acetone flowed in and resistance decreased.
  • the gas sensitivity is R a / R g (R a : sensor resistance in air, R g : sensor resistance in gas), and in the case of a p-type oxide semiconductor, gas sensitivity was defined as R g / R a .
  • the acetone response characteristics of each manufactured sensor were measured in a dry atmosphere and compared with the acetone sensitivity and sensor resistance measured in a relative humidity of 20, 50 and 80%. The detailed measuring method is as follows.
  • the atmosphere is suddenly changed to test gas (acetone 20 ppm) and exposed to the test gas for 300 seconds, and then the atmosphere is changed to dry air to maintain 1100 seconds.
  • the gas sensitivity in the dry atmosphere was measured. After that, the atmosphere is suddenly changed to air at a relative humidity of 20, 50, or 80% and maintained for 300 seconds, and then exposed to a test gas containing relative humidity of 20, 50, or 80% for 300 seconds, and the gas according to the first humidity is changed. Response characteristics were evaluated. The same procedure was repeated three more times to measure the change in gas response characteristics with moisture exposure time.
  • the value obtained by dividing the gas sensitivity in the relative humidity of 20, 50 and 80% by the gas sensitivity in the dry atmosphere was defined as the change rate of gas sensitivity (%), and the sensor resistance of the relative humidity of 20, 50 and 80% in the dry atmosphere.
  • the value divided by the sensor resistance was defined as the percentage change in sensor resistance. Therefore, it can be understood that when the gas sensitivity and sensor resistance change rate is 100%, the humidity dependency of the sensor is almost absent.
  • Comparative Example 1-1 and Comparative Example 1-2 can be seen that the hollow structure is empty inside (a, c), in the case of Comparative Example 2-1 and Comparative Example 2-2 inside the hollow structure It can be seen that it represents an egg yolk structure in which a hollow structure is additionally present (e, g). In the case of fine powders according to Example 1-1, Example 1-2, Example 2-1 and Example 2-2, which were synthesized through the same process by adding 2, 5, 12, and 30 wt% of CeO 2 , respectively. In addition, it can be seen that the hollow structure (b, d) and the yolk sac structure (f, h) are maintained regardless of the presence or absence of CeO 2 addition.
  • Example 5 is a SEM photograph of Example 3 synthesized using a solution stirring method and commercially available SnO 2 fine powder (Comparative Example 3). Referring to FIG. 5, the size of the commercially available SnO 2 fine powder was small as several nm in size (a), and after the addition of CeO 2 , almost the same structure was observed without increasing or agglomerating the size (b).
  • Example 1-1 shows Example 1-1, Comparative Example 1-1, Example 1-2, Comparative Example 1-2, Example 2-1, Comparative Example 2-1, Example 2-2 and Comparative Example using XRD. Phase analysis results for 2-2.
  • the X-ray diffraction pattern of Comparative Example 1-1 showed SnO 2 having a tetragonal structure (a1).
  • the diffraction pattern related to CeO 2 could not be confirmed (a2). This may be because the amount of added CeO 2 is very small, which is beyond the limit of XRD or because the CeO 2 nanoparticles are evenly distributed throughout the SnO 2 hollow structure.
  • Example 1-2 the diffraction pattern of Comparative Example 1-2 showed ZnO of hexagonal structure (b1).
  • no diffraction pattern related to CeO 2 was found even though the amount of CeO 2 added was higher than the XRD measurement limit (5 wt%) (b2). This shows that the added CeO 2 is very uniformly dispersed in a few nm size throughout the ZnO hollow structure.
  • Example 2-1 showed a diffraction pattern of NiO having a cubic structure (d1), and in Example 2-2, a diffraction pattern of NiO and CeO 2 appeared together (d2).
  • Example 7 shows phase analysis results of Example 3 and Comparative Example 3 using XRD.
  • Comparative Example 3 shows a diffraction pattern of SnO 2 having a tetragonal structure (a1).
  • the addition amount of CeO 2 (2 wt%) was the same as that of Example 1-1, the diffraction pattern of CeO 2 appeared together with the diffraction pattern of SnO 2 (a2). This shows that when the CeO 2 -metal oxide nanostructures are synthesized by solution stirring without using ultrasonic spray pyrolysis, CeO 2 nanoparticles are less uniformly distributed throughout the gas sensitive body than ultrasonic spray pyrolysis. .
  • FIG. 8 is a comparison result of 20 ppm acetone gas sensitive transient and gas sensitivity in the dry atmosphere and the relative humidity 80% atmosphere measured at 450 ° C.
  • Comparative Example 1-1 showed high sensitivity to 20 ppm of acetone in a dry atmosphere, but acetone sensitivity was greatly reduced when exposed to an 80% relative humidity atmosphere, and at the same time, the resistance of the sensor was also in a dry atmosphere. Significantly reduced compared to (a1 and a2). This is a general phenomenon that occurs when an n-type oxide semiconductor gas sensor such as SnO 2 is exposed to moisture, which is a major factor that degrades the performance of the sensor and causes a malfunction.
  • SnO 2 n-type oxide semiconductor gas sensor
  • Example 1-1 even if suddenly exposed to the relative humidity of 80% atmosphere, the acetone sensitivity and resistance in the fast time ( ⁇ 300 s) showed almost the same value as in the dry atmosphere (Fig. 8b1).
  • the results show that when CeO 2 is added to SnO 2 , it is possible to secure a constant gas response characteristic with high reliability regardless of the presence or absence of external moisture unlike general oxide semiconductor type gas sensors (b2).
  • Example 1-1, Example 1-2, Example 2-1, and Example 2-2 to which CeO 2 was added showed almost constant acetone sensitivity regardless of the presence and concentration of relative humidity ( b, d, f, h). This shows that the added CeO 2 prevents the poisoning of the surface of the gas sensitive body by the hydroxyl group.
  • the gas sensitivity change rate of the gas sensor according to the comparative examples was 81% (Comparative Example 1-1) and 49% ( Comparative Examples 1-2), 66% (Comparative Example 2-1), 84% (Comparative Example 2-2), while low, respectively, for the gas sensors according to the embodiments 103% (Example 1-1) , 97% (Example 1-2), 98% (Example 2-1), 103% (Example 2-2) showed values close to 100%. This shows that the addition of CeO 2 as a moisture absorber to the oxide semiconductor showing humidity dependence can almost eliminate the humidity dependence of gas sensitivity.
  • Example 10 is Comparative Example 1-1, Example 1-1, Comparative Example 1-2, Example 1-2, Comparative Example 2-1, Example 2-1, Comparative Example 2-2, and the result measured at 450 ° C. It is the result of sensor resistance comparison in the dry atmosphere and relative humidity of 20, 50, 80% of Example 2-2.
  • the relative humidity is increased due to the reaction between the water and the gas sensitive body. As the amount of electrons increases, the sensor resistance decreases (a, c, e).
  • the gas sensor according to Comparative Example 2-1 is a p-type oxide semiconductor, since the electrons generated by the reaction with moisture decreases the concentration of holes in NiO, the sensor resistance gradually increases as the humidity increases ( g).
  • the change in sensor resistance according to the humidity of gas sensors according to the comparative examples is similar to the change in resistance generated when the sensor reacts with gas (type n: decrease in resistance when gas is sensitive; type p: increase in resistance when gas is sensitive). ) Is the main cause of sensor malfunction.
  • gas sensors according to the embodiments in which CeO 2 was added showed almost constant sensor resistance regardless of the presence and concentration of external moisture (b, c, f, h).
  • the change rate of the sensor resistance which is an indicator for evaluating the reliability of the sensor calculated based on the relative humidity of 80%, is 61% (Comparative Example 1-1) and 46% (Comparative Example 1-) for the gas sensors according to the comparative examples. 2), 73% (Comparative Example 2-1), 93% (Comparative Example 2-2, dry atmosphere sensor resistance / humidity atmosphere sensor resistance), while low, respectively, 97% (for gas sensors according to embodiments) Example 1-1), 99% (Example 1-2), 100% (Example 2-1) and 100% (Example 2-2) showed values close to 100%.
  • CeO 2 nanoparticles are added to the gas sensitive material as a water absorbent, it is possible to secure not only the gas sensitivity but also the humidity stability of the sensor resistance, and a highly reliable gas that exhibits constant gas response characteristics regardless of the presence or concentration of moisture. It demonstrates that a sensor can be implemented.
  • FIG. 11 is a result of comparing the sensitivity of acetone gas of 20 ppm in the dry atmosphere and relative humidity 20, 50, 80% atmosphere of the gas sensors according to Comparative Example 3 and Example 3 measured at 450 °C.
  • acetone sensitivity and sensor resistance in a dry atmosphere and a relative humidity of 80% showed a large difference (a, c; gas sensitivity change rate: 84). %; Sensor resistance change rate: 75%).
  • the obtained fine powder of In 2 O 3 hollow structure (0.04 g) was added to 50 mL of tertiary distilled water and sonicated for 5 minutes to disperse. Then, 20 mL of ammonia / hydrogen peroxide mixed solution (1: 1) was added, and 30 The In 2 O 3 surface was washed by stirring at 80 ° C. for min. The washed solution was washed five times with water using centrifugation, and then 20 mL of polyethyleneimine (PEI, H (NHCH 2 CH 2 ) n NH 2 , Mw: ⁇ 25,000, Sigma-Aldrich, USA) was prepared.
  • PEI polyethyleneimine
  • the surface of In 2 O 3 was modified with a positive charge by mixing with solution (0.5 g / L) and stirring for 3 hours. 20 mL of polyacrylic acid (PAA, (C 3 H 4 O 2 ) n , Mv: ⁇ 450,000, Sigma-Aldrich, USA) solution (0.5 g / L) and stirred for 2 hours to modify the surface of In 2 O 3 to charge.
  • PAA polyacrylic acid
  • Example 4-2 After washing the excess PAA with water five times by centrifugation, the remaining fine powder was dispersed in 40 mL of tertiary distilled water, 2.9% by weight (Example 4-2), 5.7% by weight (Example 4-1 ), Ce (III) nitrate hexahydrate (Ce (NO 3 ) 3 6H 2 O, 99.99%, Sigma- corresponding to 10.7% by weight (Example 4-3) and 19.4% by weight (Example 4-4) Aldrich, USA) was added and stirred for 3 hours to induce Ce ions to electrostatically bond with the charge on the In 2 O 3 surface.
  • Example 4-4 synthesized fine powder uniformly coated on the In 2 O 3 hollow structure surface.
  • the synthesized fine powder was mixed with tertiary distilled water, drop-coated on an alumina substrate on which Au electrodes were formed, and heat treated at 500 ° C. for 2 hours to produce a gas sensor.
  • the manufactured sensor is alternately injected at 450 ° C with alternating air and air in a 20, 50, 80% relative humidity atmosphere or air + mixed gas in a dry atmosphere and air + mixed gas in a 20, 50, 80% relative humidity atmosphere. While measuring the change in resistance.
  • the gases were premixed and then rapidly changed in concentration using a four-way valve. The total flow rate was fixed at 100 SCCM so that the temperature difference did not occur when the gas concentration changed.
  • Example 5 CeO 2 Nanoparticles In 2 O 3 Fabrication of a gas sensor according to the present invention uniformly coated on the surface of the hollow structure (process for producing a composite for gas detection using a single process)
  • micro-sized droplets formed by the ultrasonic wave were immediately heat-treated at a flow rate of (O 2 ) 900 ° C. at a flow rate of 5 L / min, and the In 2 O 3 hollow structure was uniformly added with 5.7% by weight of CeO 2 . Synthesized. Since the manufacturing method of the sensor and the measurement of the gas sensitivity was performed in the same manner as in Example 4.
  • the obtained fine powder of In 2 O 3 hollow structure (0.04 g) was added to 50 mL of distilled water, sonicated for 5 minutes, dispersed, and then 20 mL of ammonia / hydrogen peroxide mixed solution (1: 1) was added thereto for 30 minutes. Stir at 80 ° C. to wash the In 2 O 3 surface. The washed solution was washed five times with water using centrifugation, and then 20 mL of polyethyleneimine (PEI, H (NHCH 2 CH 2 ) n NH 2 , Mw: ⁇ 25,000, Sigma-Aldrich, USA) was prepared. The surface of In 2 O 3 was modified with a positive charge by mixing with solution (0.5 g / L) and stirring for 3 hours.
  • PEI polyethyleneimine
  • PAA polyacrylic acid
  • Example 5-4 CeO 2 nanoparticles of Example 5-4) was synthesized finely coated on the In 2 O 3 hollow structure surface. Since the manufacturing method of the sensor and the measurement of the gas sensitivity was performed in the same manner as in Example 4.
  • the synthesized fine powder shows high resistance state in the air regardless of the presence of moisture and the concentration (RH 20, 50, 80%).
  • the characteristics of n-type semiconductors are shown in that resistance is decreased while the reducing gas is introduced. Therefore, gas sensitivity was defined as R a / R g (R a : sensor resistance in air, R g : sensor resistance in gas).
  • the acetone, carbon monoxide, ammonia and toluene sensitivity of the sensor were measured in a dry atmosphere and 20, 50 and 80% relative humidity, and the selectivity was calculated by comparing the gas sensitivity of acetone with that of other gases.
  • the atmosphere is suddenly changed to air containing a certain concentration of test gas and exposed to the test gas for 300 seconds, and then the atmosphere is changed to air in the dry atmosphere again for 1100 seconds.
  • the gas sensitivity in the dry atmosphere was measured while maintaining the temperature. After that, the atmosphere is suddenly changed to air at a relative humidity of 20, 50, or 80%, maintained for 300 seconds, and then exposed to a test gas containing relative humidity of 20, 50, or 80% for 300 seconds to react to the gas at the first humidity.
  • the characteristics were evaluated. After that, the same process was repeated three more times, and the change of gas-sensing characteristics with moisture exposure time was measured.
  • the gas sensitivity in the relative humidity of 20, 50, and 80% was divided by the gas sensitivity in the dry atmosphere, multiplied by 100, to define the change in gas sensitivity (%), and the sensor resistance in the relative humidity of 20, 50, and 80% was dried.
  • the value obtained by dividing the value by the gas sensitivity of the atmosphere by 100 was defined as the percentage change in sensor resistance. Therefore, if the gas sensitivity and sensor resistance change rate shows 100%, it can be understood that there is little humidity dependence of the sensor.
  • FIG. 14 is an SEM image of gas detection complexes synthesized via a layer-by-layer method after ultrasonic spray pyrolysis. Regardless of the amount of Ce added, it was confirmed that Example 4 (14d, 14e, 14f and 14g), Comparative Example 4 (14a) and Comparative Example 5 (14b, 14c, 14h and 14i) maintained hollow structures. However, in the SEM images of Comparative Examples 5-3 (FIG. 14H) and Comparative Examples 5-4 (FIG. 14I), in addition to the Ce-coated In 2 O 3 hollow structure, many CeO 2 plate-like structures and cube structures were found. In the case of Example 5-3 and Comparative Example 5-4, the amount of Ce added was so large that all CeO 2 could not be formed on the surface of the In 2 O 3 hollow structure, but it was judged to be aggregated and self-assembled.
  • FIGS. 15 and 16 show Comparative Example 4 (FIGS. 15A-15C), Example 4-1 (FIGS. 15D-15G), Example 4-3 (FIGS. 16A-16D) and Examples 4-4 (FIGS. 16E-H).
  • the thickness of the synthesized In 2 O 3 hollow structure was about 15 nm, and the thickness of the In 2 O 3 hollow structure was maintained regardless of the amount of Ce added.
  • elemental mapping elemental mapping
  • FIG. 17 is a SEM and TEM image of a gas detection composite according to Example 5 synthesized in a single process instead of a layer-by-layer process.
  • the layer-by-synthesis is that, unlike the fine powder through the layer process In 2 O 3 CeO 2 nanoparticle surface only the presence, but not the element mapping result, CeO 2 It was confirmed that the nanoparticles are uniformly distributed over the entire In 2 O 3 hollow structure (FIG. 17D).
  • Example 18 is a phase analysis result of the gas detection complexes according to Comparative Example 4, Example 4 and Comparative Example 5 using XRD.
  • Example 4-3 (f-1, f-2 and f-3) and Example 4-4 (g-1, g-2 and g-3), Comparative Example 5-3 (h-1, h- 2 and h-3) and in the X-ray diffraction patterns of Comparative Examples 5-4 (i-1, i-2 and i-3), the nanoparticles formed on the surface of In 2 O 3 have a fluorite cubic structure. It was confirmed that the CeO 2 .
  • Comparative Example 4 (a-1, a-2 and a-3), Comparative Example 5-1 (b-1, b-2 and b-3), and Comparative Example 5-2 (c-1, c- 2 and c-3), Example 4-2 (d-1, d-2 and d-3) and Example 4-1 (e-1, e-2 and e-3), the peaks associated with CeO 2 could not be confirmed. This is also due to the measurement limits of XRD, but Ce 4 + of CeO 2 is reduced due to the electrons received from In 2 O 3 is believed to be due to the presence of a large amount of Ce 3 + to lower the crystallinity of CeO 2 .
  • FIG. 20 is a graph showing changes in sensor resistance and sensitivity to various gases in a dry atmosphere and a relative humidity of 80% at a response temperature of 450 ° C. of Examples 4-1 (FIG. 20A) and Comparative Example 4 (FIG. 20B).
  • Example 4-1 the sensor resistance at drying, relative humidity 20%, relative humidity 50%, and relative humidity 80% was almost constant at 7.72, 7.34, 7.43, and 7.45 M ⁇ (see Fig. 21B).
  • Comparative Example 4 the sensor resistances of 16.0, 7.45, 5.85, and 5.41 k ⁇ at drying, relative humidity 20%, relative humidity 50%, and relative humidity 80% were significantly changed according to humidity. (See Figure 21B left).
  • Example 4-1 shows the sensitivity of 80% humidity to acetone 20 ppm, ethanol 20 ppm, hydrogen 200 ppm, carbon monoxide 200 ppm, ammonia 200 ppm, toluene 100 ppm, formaldehyde 50 ppm compared to the dry sensitivity. 93% -96% (FIG. 20A). This means that gas sensitivity is hardly affected by changes in humidity. On the other hand, in Comparative Example 4, the sensitivity in the state of 80% humidity for the same gas shows 21% to 42% of the sensitivity in the dry state (Fig. 20B). This means that the sensitivity is significantly reduced to the level of 1 / 5-1 / 3 in the presence of humidity.
  • the resistance of the gas sensor changes with humidity, it becomes very difficult to set a reference point for measuring the sensitivity.
  • the sensitivity is greatly changed in accordance with the change in humidity, it is difficult to distinguish the gas concentration.
  • the fact that the resistance and sensitivity of the sensor is hardly influenced by humidity means that the concentration of the gas can be quantitatively determined irrespective of the change in humidity.
  • the addition of CeO 2 enables the implementation of a gas sensor independent of humidity.
  • 21 shows 450 of the gas detection complexes according to Comparative Example 4, Comparative Example 5-1, Comparative Example 5-2, Comparative Example 5-2, Example 4-1, Example 4-3, and Example 4-4.
  • Comparative Examples 5-3, Comparative Examples 5-4 For, eotneunde hard to obtain reproducible results in terms of sensor measurements, which in addition to sensors for making slurry of a CeO 2 applied to In 2 O 3 CeO 2 hollow plate-like structure It is because the cube structure is disordered.
  • Comparative Example 4 the gas sensitivity of acetone 20 ppm in a dry atmosphere was very large as 22.2, but as the amount of Ce was increased, the gas sensitivity decreased until the amount of Ce was 2.33% by weight. It slightly increased in the 2.33% to 11.7% by weight, and slightly decreased or almost similar in the 11.7% to 39.9% by weight (see Figure 21a). This tendency is related to the response / recovery rate of the sensor described below.
  • the amount of Ce increased until the amount of Ce added up to 11.7% by weight, and then slightly decreased or nearly similar after that (Fig. 21B). This means that when 11.7% by weight of Ce is added, the electrons of the In 2 O 3 hollow structure are almost depleted. When more than 11.7% by weight of Ce is added, the excessive CeO 2 has electrons from In 2 O 3 . It means not to come.
  • the resistance of the sensor according to the embodiments of the present invention is 0.5 M ⁇ -10 M ⁇ level, it is easy to manufacture a gas sensor, it is possible to reduce to 0.05 M ⁇ -1 M ⁇ level by adjusting the sensor interval.
  • the gas sensitivity of the composite according to Comparative Example 4 in the relative humidity of 20, 50, and 80% of the atmosphere was 7.33 in the relative humidity of 20%, 5.41 in the atmosphere of 50% relative humidity, and 4.76 in the relative humidity of 80%. Compared with 22.2, it showed a significantly reduced humidity dependence (Fig. 21a left figure).
  • the change rate of gas sensitivity according to humidity was calculated.
  • Comparative Example 4 36.6 in 20% relative humidity, 24.7 in 50% relative humidity, 24.7 in 80% relative humidity, and 80% relative humidity. As 20.7, the relative humidity tended to decrease gradually (Figure 21C left).
  • the change rate (%) according to the humidity of the sensor resistance was 46.7 in the relative humidity 20% atmosphere in the comparative example 4, 36.7 in the relative humidity 50% atmosphere, 35.4 in the relative humidity 80% atmosphere
  • the temperature tended to decrease gradually.However, when 11.7% by weight of Ce was added, it was 95.0 in 20% relative humidity and 96.3 in 50% relative humidity. It was 96.5 in the atmosphere of relative humidity 80%, showing a value close to 100 (FIG. 21D). This shows that in the case of In 2 O 3 hollow structure with 11.7 wt% Ce added, the gas sensitivity to acetone can be measured almost uniformly regardless of the presence and concentration of moisture.
  • FIG. 22 is a graph showing 90% reaction rate and recovery rate of the sensor according to the amount of Ce added.
  • 90% reaction rate all showed a fast reaction rate within several seconds regardless of the amount of Ce added (FIG. 22A).
  • the recovery rate was greatly increased until 2.33% by weight of Ce was added, but then gradually decreased (Fig. 22B).
  • the recovery mechanism of the sensor is a process of adsorption of oxygen in the atmosphere back to the sensitive material, which is directly related to the oxygen adsorption capacity of the sensitive material.
  • In 2 O 3 sensor with 2.33% by weight of Ce which is the fastest recovery rate, suggests that the oxygen adsorption capacity is superior to other sensors.
  • FIG. 23 is a graph comparing acetone gas sensitive transients and gas sensitivity of 20 ppm in a dry atmosphere and a relative humidity 80% atmosphere of Comparative Example 4 (23a) and Example 4-1 (23b).
  • FIG. Comparative Example 4 showed a large difference in gas sensitivity and sensor resistance between the dry atmosphere and the relative humidity of 80% (23a), while Example 4-1 changed the gas sensitivity and sensor resistance of the dry atmosphere and the relative humidity of 80%. There was little (23b). This is because CeO 2 nanoparticles are uniformly distributed on the surface of In 2 O 3 hollow structure to effectively protect the surface of In 2 O 3, the main sensitizer, from moisture coming from outside. And a sensor representing the sensor resistance.
  • Example 24 is a graph showing changes in sensor resistance and gas sensitivity according to acetone gas sensitive transients and measurement times of 20 ppm in a relative humidity of 20, 50, and 80% of Comparative Example 4 (24a) and Example 4-1 (24b). .
  • Comparative Example 4 the gas sensitivity and the sensor resistance showed a large difference from the dry atmosphere regardless of the relative humidity (FIG. 24A).
  • a 11.7% by weight of Ce is applied In 2 O 3, if a hollow structure at a very high speed, regardless of the concentration of moisture ( ⁇ 300 s) the sensitivity of the dry atmosphere gas and the sensor resistance of gas sensitivity and the sensor of the humidity of the atmosphere It appeared to be similar to the resistance (FIG. 24B).
  • This shows that Example 4-1 can measure the gas sensitivity to acetone almost constantly regardless of the presence and concentration of moisture in a very fast time.
  • FIG. 25 is a graph comparing gas sensitivity and acetone selectivity for 20 ppm acetone and other interfering gases in a dry atmosphere of Comparative Example 4 (25a) and Example 4-1 (25b) at a relative humidity of 80%.
  • This characteristic is to investigate the gas response characteristics for diagnosing the disease from diabetic patients, and since it is measured from patients who are not drinking, it does not consider gas sensitivity to ethanol and other biomarkers that may occur from patients. The gas was considered as an interfering gas.
  • Comparative Example 4 showed a high selectivity of 3 or more for acetone in a dry atmosphere (25a).
  • Example 4-1 Still showed high selectivity for acetone of 3 or more despite the decrease in gas sensitivity due to the addition of Ce (25b).
  • FIG. 26 is a graph showing the transient 26a and the gas sensitivity 26b for each acetone gas concentration in the dry atmosphere and the relative humidity 80% atmosphere of Example 4-1.
  • Example 4-1 showed different gas sensitivity depending on the concentration of acetone in an atmosphere of drying and relative humidity of 80%, the gas sensitivity and sensor resistance at this time was constant regardless of the presence of moisture (Fig. 26a). This shows that Example 4-1 can detect the gas present in the atmosphere in real time regardless of the presence and concentration of moisture.
  • Acetone is an environmental pollutant gas and at the same time, 300 to 900 ppb is detected in the exhalation of a normal person, and 1800 ppb or more is detected in the exhalation of a diabetic patient.
  • Example 4-1 Since the acetone measurement limit of Example 4-1 is at least 500 ppb (FIG. 26B), it is expected that the gas sensor according to the present invention can be fully utilized for disease diagnosis sensors due to exhalation, such as diabetes self-diagnosis.
  • FIG. 27 is a sensitive transient for 20 ppm of acetone gas in the dry atmosphere and 80% relative humidity atmosphere of Example 5.
  • Gas detection composite according to the present invention and a gas sensor comprising the same as a gas sensitive layer can quickly detect the gas to be detected with high sensitivity irrespective of the presence and concentration of moisture, bar driver drinking, explosive Gas detection, exhaust gas detection, harmful gas detection, indoor and outdoor environmental gas detection sensor, disease self-diagnosis gas sensor, artificial olfactory sensor, such as oxide semiconductor type gas sensor can be useful and widely used.

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Abstract

La présente invention concerne un complexe pour la détection de gaz qui présente des performances de détection stables et fiables même dans un environnement humide, un procédé de fabrication de celui-ci, un capteur de gaz comprenant le complexe pour la détection de gaz sous la forme d'une couche de détection de gaz, et un procédé de fabrication de celui-ci et, plus particulièrement, un complexe pour la détection de gaz comprenant : une nanostructure d'un semi-conducteur à oxyde choisi dans le groupe constitué de SnO2, ZnO, WO3, NiO et In2O3 ; et un additif CeO2 supporté sur la nanostructure, un procédé de fabrication de celui-ci, un capteur de gaz comprenant le complexe pour la détection de gaz sous la forme d'une couche de détection de gaz, et un procédé de fabrication de celui-ci. La présente invention concerne un complexe pour la détection de gaz susceptible de détecter rapidement un gaz destiné à être détecté avec une sensibilité élevée, indépendamment de la présence ou de la concentration d'humidité, au moyen d'une nanostructure de semi-conducteur à oxyde à laquelle est ajouté du CeO2 uniformément ; un capteur de gaz comprenant le complexe pour la détection de gaz sous la forme d'une couche de détection de gaz ; et un procédé de fabrication de celui-ci.
PCT/KR2016/008770 2015-08-10 2016-08-10 Complexe pour détection de gaz hautement fiable sans l'influence de l'humidité, procédé pour sa fabrication, capteur de gaz comprenant le complexe pour la détection de gaz, et son procédé de fabrication WO2017026785A1 (fr)

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KR1020150112273A KR101594734B1 (ko) 2015-08-10 2015-08-10 산화인듐 중공구조 및 산화세륨 나노입자를 포함하는 가스 검출용 복합체, 그 제조방법 및 이를 포함하는 가스센서
KR1020160098788A KR20180015369A (ko) 2016-08-03 2016-08-03 습기의 영향이 배제된 고신뢰성 가스 검출용 복합체, 그 제조방법, 상기 가스 검출용 복합체를 포함하는 가스 센서 및 그 제조방법
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US20230273139A1 (en) * 2018-05-30 2023-08-31 Korea University Research And Business Foundation Gas detection complex and method for producing same, gas sensor comprising gas detection complex and method for manufacturing same
CN109632893A (zh) * 2019-01-11 2019-04-16 东北大学 一种基于p-n异质结结构NiO-In2O3复合纳米球的气体传感器
CN109632893B (zh) * 2019-01-11 2022-02-25 东北大学 一种基于p-n异质结结构NiO-In2O3复合纳米球的气体传感器
CN109975367A (zh) * 2019-03-11 2019-07-05 陕西科技大学 基于Ag量子点修饰的小于60nm的WO3-SnO2实心纳米球丙酮传感器及制备方法
CN110161086A (zh) * 2019-05-20 2019-08-23 南京工业大学 一种高选择性高灵敏度的半导体丙酮传感器的制备方法
CN111188129A (zh) * 2020-01-16 2020-05-22 中国农业科学院农业信息研究所 一种乙烯传感器及乙烯敏感薄膜的制备方法

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