CN104422716A - Preparation method of gas sensor gas sensitive film based on In2O3 nanowire - Google Patents
Preparation method of gas sensor gas sensitive film based on In2O3 nanowire Download PDFInfo
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- CN104422716A CN104422716A CN201310407887.1A CN201310407887A CN104422716A CN 104422716 A CN104422716 A CN 104422716A CN 201310407887 A CN201310407887 A CN 201310407887A CN 104422716 A CN104422716 A CN 104422716A
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Abstract
The invention relates to a preparation method of a gas sensor gas sensitive film based on an In2O3 nanowire. The method comprises the steps of synthesizing a porous semiconductor In2O3 nano material in a two-step chemical conversion method, primarily separating and purifying the porous semiconductor In2O3 nano material to obtain the In2O3 nanowire with relatively high purity, and assembling a semiconductor gas sensor by adopting the In2O3 nanowire as a gas-sensitive material. The working principle of the gas sensor is to carry out the detection and analysis according to the variation of an electric signal (resistance, voltage, current, etc.) of the semiconductor In2O3 nanowire material exposed in the air and in a to-be-detected gas. The gas sensor has relatively good response to conventional organic volatile compounds (VOCs) such as ethanol, acetone and formaldehyde as well as toxic, harmful and environmental-pollution gases such as ammonia gas and hydrogen sulfide; moreover, the response degree (sensitivity) is directly related to the concentration (or content) of the detected gas, and the gas sensor gas sensitive film can be used for online detection of the gas.
Description
Technical field
The present invention relates to a kind of preparation method of semiconductor gas sensor air-sensitive film, specifically, is by In
2o
3nano wire, as gas sensing property material, is assembled into semiconductor gas sensor, realizes the analysis to gas and detection.
Background technology
Along with the raising of human security and health perception, in the urgent need to flammable explosive gas and the toxic and harmful of monitoring air, family and various production, life area, to prevent the generation of security incident, ensure the safety of the person and property.Detection analysis at present for gas is mainly still based on large-scale instrument analysis, as analytical instrument such as gas chromatography, infrared absorption, analysis of thermal conductivity, how the complex pretreatment of these large-scale instruments, complex operation, instrument maintenance cost intensive, can not carry out field monitoring.Therefore, cost of development is cheap, highly sensitive, portable gas sensor is extremely urgent.And gas sensor performance and gas sensitive closely related, therefore high performance gas sensitive more and more receives the concern of people.Although various metal oxide semiconductor materials have been widely used in the gas sensitive of gas sensor, its lower sensitivity has still limited its popularization to a certain extent.
The nano thread structure of metal oxide, because its specific surface area is large, surfactivity is high, thus obtains very responsive to the environment representation of surrounding, be expected to reveal excellent air-sensitive performance to gas meter to be measured.Further, the nano material manufacture craft of these metal oxides is simple, with low cost, simple and easy to do, promotes on a large scale lay a good foundation for it.
Based on these advantages of metal oxide nano-material, designed as semiconductor gas sensor air-sensitive film, the detection sensitivity of gas can be improved, shortened response and release time.
Summary of the invention
The object of the invention is to propose one based on In
2o
3the preparation method of the gas sensor air-sensitive film of nano wire, to improve detection sensitivity to gas, to shorten response and release time.To achieve these goals, the technical scheme that the design adopts is:
By commercialization In
2o
3powder preparation In
2o
3nano material, is separated and obtains porous In
2o
31-dimention nano wire material, and as preparing the air-sensitive film of sensor.
Include In
2o
3the preparation of nano material, In
2o
3the separation of nano wire and the assembling of gas sensor air-sensitive film;
(1) the commercialization In of pasty state will be modulated into water
2o
3powder uniform application, at the inwall of quartz boat, puts into the center of quartz tube furnace after drying, pyroreaction 3-8h in ammonia flow; After reaction terminates, quartz ampoule is made to slowly cool to room temperature; By the product high-temperature calcination 2-5h in air atmosphere obtained in quartz boat, after reaction terminates, progressively cool to room temperature;
(2) the oarse-grained metal indium pellet of product removing more than diameter 2mm step (1) obtained, remaining nano material and Metallic Indium Powder are scattered in organic solvent; By whole for dispersion soln sucking-off, after the dispersion soln of sucking-off stirs 6-12h, centrifugal, collect gained supernatant, after supernatant is again centrifugal, collects the precipitation obtained, precipitation is all scattered in absolute ethyl alcohol;
(3) a Ni-Cr heater strip is passed by the ceramic pipe with a pair gold electrode and platinum lead-in wire; Get nano wire ethanol dispersion soln, slowly drip and be coated in film forming between ceramic pipe outside surface a pair gold electrode, aging 24h.
Described commercialization In
2o
3for quality purity is more than or equal to the In of 99.99%
2o
3.
The flow velocity of step (1) described ammonia flow is 100-500mL/min; In ammonia, high temperature refers to 600-800 DEG C.
The air stream of step (1) described air atmosphere to be flow velocity be 100-500mL/min; In air atmosphere, high temperature refers to 500-700 DEG C.
Step (2) described centrifugal speed is 2000-5000rpm, and centrifugation time is 1-10min.
Step (2) described organic solvent is one or two or more kinds in ethanol, toluene, hexane, normal hexane, ethylene glycol, trichlorophenol, chloroform etc.
To be coated in length × external diameter described in step (3) be the nano wire ethanol dispersion soln volume of 4mm × 1.2mm ceramic pipe outside surface is 5-200 μ L.
Step (3) described aging temperature controls at 400-500 DEG C.
Air-sensitive film can be used for the real-time detection of volatile organic compounds.
What the synthesis of nano wire adopted is two step chemical transformations.First by In
2o
3at NH
3nitrogenize in atmosphere, prepares InN nano wire, then InN nano wire is oxidized to In in the air stream
2o
3nano wire, due to Kinkendal Effect, forms metal nitride by ammonia metal nitride oxide, then is oxidized back metal oxide in atmosphere.The metal oxide of new formation is coated on unreacted metal nitride surface, the nitrogen that reaction produces is assembled under metal oxide layer, finally break through metal oxide layer, form ultra-fine nano-pore structure, more oxygen enters from hole, reacts, go round and begin again with the metal nitride of lower one deck, form the porosint with superfine nano microcellular structure, increase the specific surface area of nano-material further.
In the product obtained, except In
2o
3outside nano wire, also have Metallic Indium Powder, indium pellet, In
2o
3micron film, micron tube etc.Through centrifuging, according to the density of different product in chloroform and the difference of viscosity, under different centrifugal force, the In that purity is higher can be isolated
2o
3nano wire.
Isolated porous In
2o
3nano wire disperses via ethanol, drips and is coated on ceramic pipe, easy to make, is easy to repetition.
The present invention relates to a kind of based on In
2o
3the preparation method of the gas sensor air-sensitive film of nano wire.With the synthesizing porous semiconductor In of two step chemical transformations
2o
3nano material, obtains the In that purity is higher after initial gross separation purifying
2o
3nano wire, and in this, as gas sensing property material, be assembled into semiconductor gas sensor.The principle of work of this gas sensor is according to semiconductor In
2o
3change that nano-material is exposed to electric signal (resistance, voltage, electric current etc.) in air and gas to be measured is to carry out determination and analysis.Gas sensor can common are machine escaping gas (VOCs) to ethanol, acetone, formaldehyde etc. and the poisonous and harmful such as ammonia, sulfuretted hydrogen environmental contamination gas has good response, and its responsiveness (i.e. sensitivity) is directly related with the concentration (or content) of gas to be measured, can be used for the on-line checkingi of gas.
Advantage of the present invention
1. as the In preparing semiconductor gas sensor
2o
3be the nano wire one-dimensional material of porous, improve the sensitivity to gas, shorten response and release time.
2. sensor air-sensitive film manufacture craft is simple, with low cost, simple and easy to do.
Figure of description
Fig. 1. the In prepared
2o
3the scanning electron microscopic picture of nano material.
Fig. 2. the In that (a) that process separation obtains is purer
2o
3nano wire; (b) other scanning electron microscopic picture of structure.
Fig. 3. (a) semiconductor gas sensor schematic diagram; B () air-sensitive performance tests circuit diagram used; The ethanol response curve of (c) variable concentrations.
Embodiment
(1) In
2o
3the preparation of nano material.Take the In of 1.5g
2o
3powder (Aladdin company, 99.99%) is in quartz boat (5cm × 2.8cm × 1.4cm).Several distilled water are added, by In in quartz boat
2o
3powder is modulated into pasty state, and it spreads upon on the inwall of quartz boat by medication spoon uniformly, puts into ventilating kitchen slowly dry.Again quartz boat is put into the center of quartz tube furnace (60cm × 3.535cm × 3.106cm).Ammonia 30min is passed into the flow velocity of 200mL/min, to get rid of the air in quartz ampoule in quartz ampoule.Then, then by quartz ampoule in the ammonia of 200mL/min, be heated rapidly to 730 DEG C from room temperature, and keep reaction 6h.After reaction terminates, close quartz tube furnace, make quartz ampoule progressively cool to room temperature.Finally, by the product obtained in quartz boat, in the air atmosphere of 200mL/min, be heated to 600 DEG C from room temperature, and keep 3h, after reaction terminates, close quartz tube furnace, progressively cool to room temperature.
(2) In
2o
3the separation of nano wire.The metal indium pellet of the above particle of material removing major diameter 2mm step (1) obtained, remaining nano material and Metallic Indium Powder (Fig. 1), all can be dispersed in it in the chloroform of 20mL.Metallic Indium Powder speed of sedimentation in chloroform is exceedingly fast, and nano material also has little time deposition, therefore all can draw out by dispersion liquid with liquid-transfering gun, is placed in another 20mL bottle.After dispersion liquid in bottle is stirred 12h on magnetic stirring apparatus, then be placed in supercentrifuge, centrifugal 3min under 2000rpm, by supernatant sucking-off.Collect the supernatant of gained, centrifugal 5min under 9000rpm, topples over by supernatant completely, collects and is precipitated (Fig. 2), finally precipitation be all dispersed in absolute ethyl alcohol.
(3) assembling of detector.As Fig. 3 a, pass a Ni-Cr heater strip 1 by the ceramic pipe 4 (length × external diameter × internal diameter is 4mm × 1.2mm × 0.8mm) with a pair gold electrode 3 and platinum lead-in wire 2, be used to provide the temperature required for test; A pair gold electrode 3 is wound in the outside surface of ceramic pipe 4 spaced reciprocally, is respectively equipped with platinum lead-in wire 2, has placed a Ni-Cr heater strip 1 in ceramic pipe 4 on a pair gold electrode 3.Platinum lead-in wire and Ni-Cr heater strip are weldingly fixed on pedestal respectively.Fig. 3 b is by being adopted circuit diagram.Get the nano wire ethanol dispersion soln of 200 μ L, slowly drip to be coated between ceramic pipe outside surface a pair gold electrode 3 and become air-sensitive film 5.Then, whole sensor is connected to 400-500 DEG C of aging 24h in Testing system of gas-sensor built (WS-30A, the bright Sheng in Zhengzhou), heating voltage time aging controls at 4V.
(4) air-sensitive test experiments.According to calculating, draw quantitative ethanol solution and be placed in airtight system, treat that it volatilizees completely, namely obtain the concentration of required ethanol.
Concrete operations are as follows: first open WS-30A air-sensitive test macro, expose in atmosphere, plug load card, start test.After its electric signal is stable, quantitatively draw respectively 1 μ L, 2 μ L, 3 μ L, 4 μ L, 5 μ L absolute ethyl alcohol be placed on the evaporator of air-sensitive test macro, air chest on cover, presses " evaporation " button of front control panel, does not unclamp, after several seconds, liquid can volatilize completely, unclamp, the static volumetric method of employing, in closed container again, concentration needed for gas is obtained by the calculating of the Ideal-Gas Equation, relatively be should be 20ppm, 40ppm, 60ppm, 80ppm, 100ppm.WS-30A air-sensitive test macro records the change curve (as shown in Figure 3 c) of the electric signal that different absolute ethyl alcohol concentration produces in the corresponding closed container of air-sensitive film automatically.
Claims (10)
1. based on In
2o
3the preparation method of the gas sensor air-sensitive film of nano wire, is characterized in that: by commercialization In
2o
3powder preparation In
2o
3nano material, is separated and obtains porous In
2o
31-dimention nano wire material, and as preparing the air-sensitive film of sensor.
2. method according to claim 1, is characterized in that: include In
2o
3the preparation of nano material, In
2o
3the separation of nano wire and the assembling of gas sensor air-sensitive film;
(1) the commercialization In of pasty state will be modulated into water
2o
3powder uniform application, at the inwall of quartz boat, puts into the center of quartz tube furnace after drying, pyroreaction 3-8h in ammonia flow; After reaction terminates, quartz ampoule is made to slowly cool to room temperature; By the product high-temperature calcination 2-5h in air atmosphere obtained in quartz boat, after reaction terminates, progressively cool to room temperature;
(2) the oarse-grained metal indium pellet of product removing more than diameter 2mm step (1) obtained, remaining nano material and Metallic Indium Powder are scattered in organic solvent; By whole for dispersion soln sucking-off, after the dispersion soln of sucking-off stirs 6-12h, centrifugal, collect gained supernatant, after supernatant is again centrifugal, collects the precipitation obtained, precipitation is all scattered in absolute ethyl alcohol;
(3) a Ni-Cr heater strip is passed by the ceramic pipe with a pair gold electrode and platinum lead-in wire; Get nano wire ethanol dispersion soln, slowly drip and be coated in film forming between ceramic pipe outside surface a pair gold electrode, aging 24h.
3. method according to claim 1 and 2, is characterized in that: described commercialization In
2o
3for quality purity is more than or equal to the In of 99.99%
2o
3.
4. method according to claim 2, is characterized in that: the flow velocity of step (1) described ammonia flow is 100-500mL/min; In ammonia, high temperature refers to 600-800 DEG C.
5. preparation method according to claim 2, is characterized in that: the air stream of step (1) described air atmosphere to be flow velocity be 100-500mL/min; In air atmosphere, high temperature refers to 500-700 DEG C.
6. preparation method according to claim 2, is characterized in that: step (2) described centrifugal speed is 2000-5000rpm, and centrifugation time is 1-10min.
7. preparation method according to claim 2, is characterized in that: step (2) described organic solvent is one or two or more kinds in ethanol, toluene, hexane, normal hexane, ethylene glycol, trichlorophenol, chloroform etc.
8. preparation method according to claim 2, is characterized in that: to be coated in length × external diameter described in step (3) be the nano wire ethanol dispersion soln volume of 4mm × 1.2mm ceramic pipe outside surface is 5-200 μ L.
9. preparation method according to claim 2, is characterized in that: step (3) described aging temperature controls at 400-500 DEG C.
10. preparation method according to claim 2, is characterized in that: air-sensitive film can be used for the real-time detection of volatile organic compounds.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104897727A (en) * | 2015-05-22 | 2015-09-09 | 兰州大学 | Gas sensor for high-sensitivity multi-gas detection |
| CN105758894A (en) * | 2015-12-01 | 2016-07-13 | 中国科学院上海技术物理研究所 | Semiconductor sensor and testing circuit of hydrogen sulfide gas |
| CN106290728A (en) * | 2016-08-08 | 2017-01-04 | 三峡大学 | A kind of gas sensitive detecting formaldehyde and preparation method thereof |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101182031A (en) * | 2007-11-27 | 2008-05-21 | 山东大学 | Method for preparing indium oxide nano thread ordered aggregation |
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101182031A (en) * | 2007-11-27 | 2008-05-21 | 山东大学 | Method for preparing indium oxide nano thread ordered aggregation |
Non-Patent Citations (2)
| Title |
|---|
| SANG KYOO LIM等: "Preparation of mesoporous In2O3 nanofibers by electrospinning and their application as a CO gas sensor", 《SENSORS AND ACTUATORS B》 * |
| 李锋锐: "氮化铟及氧化铟纳米结构的制备及其表征", 《中国优秀硕士学位论文全文数据库工程科技Ⅰ辑》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104897727A (en) * | 2015-05-22 | 2015-09-09 | 兰州大学 | Gas sensor for high-sensitivity multi-gas detection |
| CN105758894A (en) * | 2015-12-01 | 2016-07-13 | 中国科学院上海技术物理研究所 | Semiconductor sensor and testing circuit of hydrogen sulfide gas |
| CN106290728A (en) * | 2016-08-08 | 2017-01-04 | 三峡大学 | A kind of gas sensitive detecting formaldehyde and preparation method thereof |
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| CN104422716B (en) | 2017-05-03 |
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