阅读说明：本技术 一种氧化铟纳米线的制备方法、含氧化铟纳米线的no2传感器的制法、传感器 (Preparation method of indium oxide nanowire and NO containing indium oxide nanowire2Method for manufacturing sensor and sensor ) 是由 张博 包楠 王涛 倪屹 于 2020-12-04 设计创作，主要内容包括：本发明提供一种基于氧化铟纳米线的制备方法,可以制备直径在50 nm～100nm的一维In-2O-3纳米线,将此一维In-2O-3纳米线覆盖在传感器载体的外表面,制备的传感器可以使用在室温的场合中,具备更高的灵敏度,较短的响应、恢复时间。同时,本发明也公开了一种基于氧化铟纳米线的NO-2传感器的制备方法、一种基于氧化铟纳米线的NO-2传感器。(The invention provides a preparation method based on indium oxide nanowires, which can be used for preparing one-dimensional In with the diameter of 50 nm-100 nm 2 O 3 A nanowire formed by one-dimensional In 2 O 3 The nanowire covers the outer surface of the sensor carrier, and the prepared sensor can be used in the room temperature occasion, and has higher sensitivity and shorter response and recovery time. Meanwhile, the invention also discloses NO based on the indium oxide nanowire 2 Preparation method of sensor and NO based on indium oxide nanowire 2 A sensor.)

1. A preparation method of an indium oxide nanowire is characterized by comprising the following steps:

a 1: weighing indium nitrate hydrate and N, N-dimethylformamide according to the mass ratio of 5/100-8/100, placing the weighed indium nitrate hydrate and N, N-dimethylformamide into a vessel, and then stirring until the indium nitrate is completely dissolved to obtain a first mixed solution;

a 2: taking the N, N-dimethylformamide in the step a1 as a reference, weighing polyvinylpyrrolidone according to the mass ratio of 10/100-20/100, putting the polyvinylpyrrolidone into the first mixed solution, stirring at room temperature to finally obtain a transparent and uniform viscous solution, and recording the viscous solution as: a second mixed solution;

a 3: preparing an injector, wherein a needle head of the injector is a needle head special for electrostatic spinning;

the inner diameter of the electrostatic spinning special needle is 0.41mm, and the outer diameter of the electrostatic spinning special needle is 0.71 mm;

the propelling speed of the injector is 0.1-0.6 ml/h, the voltage is set to be 5-20 kv, the receiving distance is set to be 10-20 cm, and the environmental humidity is controlled to be 10-50% RH;

a 4: preparing a receiving roller for receiving a nonwoven fabric film; transferring the second solution into the injector for electrostatic spinning;

a 6: after enough electrostatic spinning samples are obtained, taking down the non-woven fabric membrane, and putting the non-woven fabric membrane into a muffle furnace for calcination; setting the temperature rise rate of the muffle furnace to be 2-10 ℃/min, raising the temperature to 600-900 ℃, and then preserving the temperature for 2-3 h; naturally cooling at a certain temperature to obtain In₂O₃A nanowire powder sample;

said In₂O₃In contained In nanowire powder sample₂O₃The diameter of the nanowire is 50 nm-100 nm.

2. NO containing indium oxide nanowire₂The preparation method of the sensor is characterized by comprising the following steps:

b 1: preparing a sensor carrier having a gas sensor function;

b 2: putting the In₂O₃The method comprises the following steps of (1) mixing a nano wire powder sample and deionized water according to the ratio of 2-5: 1, and grinding the mixture to obtain the product containing In₂O₃A third mixed solution of nanowire paste;

b 3: uniformly and completely covering the third mixed solution on the outer surface of the sensor carrier, and ensuring that the third mixed solution completely covers the electrode to form a sensitive material film of 10-30 microns;

b 4: baking the sensor carrier coated with the sensitive material film under an infrared lamp for 20-30 min, and calcining the sensor carrier at 150-200 ℃ for 2-3 h to obtain room-temperature NO based on the indium oxide nanowire₂A sensor.

3. NO containing indium oxide nanowires according to claim 2₂The preparation method of the sensor is characterized by comprising the following steps: it also includes the following steps:

b 5: penetrating a nickel-cadmium alloy coil into the sensor carrier to serve as a heating wire, and obtaining a semi-finished sensor product;

b 6: welding and packaging the semi-finished product of the sensor according to a general indirectly heated gas sensitive element to obtain the room temperature NO based on the indium oxide nanowire with the heating function₂A sensor.

4. NO containing indium oxide nanowires according to claim 2₂The preparation method of the sensor is characterized by comprising the following steps: the sensor carrier is realized based on the existing commercial tubular gas sensor.

5. NO containing indium oxide nanowire₂Sensor, its characterized in that, it includes sensor carrier, its characterized in that: the sensor carrier includes: al (Al)₂O₃A ceramic tube disposed on the Al₂O₃The sensing annular gold electrode is arranged on the periphery of the ceramic tube, and a platinum wire is welded on the annular gold electrode; the In is uniformly covered on the outer surface of the annular gold electrode for sensing₂O₃And the sensitive material film is formed by the nanowires.

6. NO containing indium oxide nanowires according to claim 5₂A sensor, characterized by: the Al is₂O₃The In is also uniformly covered on the outer surface of the ceramic tube₂O₃The sensitive material film is composed of nanowires.

7. NO containing indium oxide nanowires according to claim 5₂A sensor, characterized by: it also comprises a heating wire which penetrates through the Al₂O₃A body of a ceramic tube; the heating wire is realized based on a nickel-cadmium alloy coil.

8. NO containing indium oxide nanowires according to claim 5₂A sensor, characterized by: the Al is₂O₃The length of the ceramic tube is 4-4.5 mm, the inner diameter is 0.8-1.0 mm, the outer diameter is 1.2-1.5 mm, and the width of the annular gold electrode is 0.5-1.0 mm; the resistance of the nickel-cadmium alloy coil is 30~40Ω。

9. NO containing indium oxide nanowires according to claim 6₂A sensor, characterized by: the sensor carrier also comprises an illumination module, and the illumination module performs visible light illumination on the sensitive material film covered on the surface of the sensor carrier.

Technical Field

The invention relates to the technical field of gas sensor manufacturing, in particular to a preparation method of an indium oxide nanowire and NO containing the indium oxide nanowire₂A method of manufacturing a sensor, and a recovery method.

Background

Nitrogen dioxide (NO)₂) Is a typical poisonous and harmful gas, excessive NO₂The traditional Chinese medicine composition has the advantages that strong stimulation is generated on the respiratory tract of people, so that dyspnea, pain and pulmonary edema are caused, and finally, the health of the people is greatly damaged. Up to now, the marketThe above gas sensors are widely used, and among them, the metal oxide semiconductor gas sensor is widely used because of its advantages of excellent performance, simple manufacturing, low cost, etc. However, prior art NO based on metal oxide semiconductor₂The problems of low sensitivity, long response and recovery time, high working temperature and the like of the sensor generally exist, so that the NO based on the metal oxide semiconductor₂Sensors can only be used in limited situations.

Disclosure of Invention

In order to solve the problem of NO based on metal oxide semiconductor in the prior art₂The invention provides a preparation method based on an indium oxide nanowire, which has the problems of low sensitivity, long response and recovery time and high working temperature. Meanwhile, the invention also discloses NO based on the indium oxide nanowire₂Preparation method of sensor and NO based on indium oxide nanowire₂A sensor.

The technical scheme of the invention is as follows: a preparation method of an indium oxide nanowire is characterized by comprising the following steps:

a 1: weighing indium nitrate hydrate and N, N-dimethylformamide according to the mass ratio of 5/100-8/100, placing the weighed indium nitrate hydrate and N, N-dimethylformamide into a vessel, and then stirring until the indium nitrate is completely dissolved to obtain a first mixed solution;

a 2: taking the N, N-dimethylformamide in the step a1 as a reference, weighing polyvinylpyrrolidone according to the mass ratio of 10/100-20/100, putting the polyvinylpyrrolidone into the first mixed solution, stirring at room temperature to finally obtain a transparent and uniform viscous solution, and recording the viscous solution as: a second mixed solution;

a 3: preparing an injector, wherein a needle head of the injector is a needle head special for electrostatic spinning;

the inner diameter of the electrostatic spinning special needle is 0.41mm, and the outer diameter of the electrostatic spinning special needle is 0.71 mm;

the propelling speed of the injector is 0.1-0.6 ml/h, the voltage is set to be 5-20 kv, the receiving distance is set to be 10-20 cm, and the environmental humidity is controlled to be 10-50% RH;

a 4: preparing a receiving roller for receiving a nonwoven fabric film; transferring the second solution into the injector for electrostatic spinning;

a 6: after enough electrostatic spinning samples are obtained, taking down the non-woven fabric membrane, and putting the non-woven fabric membrane into a muffle furnace for calcination; setting the temperature rise rate of the muffle furnace to be 2-10 ℃/min, raising the temperature to 600-900 ℃, and then preserving the temperature for 2-3 h; naturally cooling at a certain temperature to obtain In₂O₃A nanowire powder sample;

said In₂O₃In contained In nanowire powder sample₂O₃The diameter of the nanowire is 50 nm-100 nm.

NO containing indium oxide nanowire₂The preparation method of the sensor is characterized by comprising the following steps:

b 1: preparing a sensor carrier having a gas sensor function;

b 2: putting the In₂O₃The method comprises the following steps of (1) mixing a nano wire powder sample and deionized water according to the ratio of 2-5: 1, and grinding the mixture to obtain the product containing In₂O₃A third mixed solution of nanowire paste;

b 3: uniformly and completely covering the third mixed solution on the outer surface of the sensor carrier, and ensuring that the third mixed solution completely covers the electrode to form a sensitive material film of 10-30 microns;

b 4: baking the sensor carrier coated with the sensitive material film under an infrared lamp for 20-30 min, and calcining the sensor carrier at 150-200 ℃ for 2-3 h to obtain room-temperature NO based on the indium oxide nanowire₂A sensor;

it is further characterized in that:

it also includes the following steps:

b 5: penetrating a nickel-cadmium alloy coil into the sensor carrier to serve as a heating wire, and obtaining a semi-finished sensor product;

b 6: welding and packaging the semi-finished product of the sensor according to a general indirectly heated gas sensitive element to obtain the sensor with a heating functionRoom temperature NO based on indium oxide nanowires₂A sensor;

the sensor carrier is realized based on the existing commercial tubular gas sensor.

NO containing indium oxide nanowire₂Sensor, its characterized in that, it includes sensor carrier, its characterized in that: the sensor carrier includes: al (Al)₂O₃A ceramic tube disposed on the Al₂O₃The sensing annular gold electrode is arranged on the periphery of the ceramic tube, and a platinum wire is welded on the annular gold electrode; the In is uniformly covered on the outer surface of the annular gold electrode for sensing₂O₃And the sensitive material film is formed by the nanowires.

It is further characterized in that:

the Al is₂O₃The In is also uniformly covered on the outer surface of the ceramic tube₂O₃The sensitive material film is composed of nanowires;

it also comprises a heating wire which penetrates through the Al₂O₃A body of a ceramic tube; the heating wire is realized based on a nickel-cadmium alloy coil;

the Al is₂O₃The length of the ceramic tube is 4-4.5 mm, the inner diameter is 0.8-1.0 mm, the outer diameter is 1.2-1.5 mm, and the width of the annular gold electrode is 0.5-1.0 mm; the resistance of the nickel-cadmium alloy coil is 30-40 omega;

the sensor carrier also comprises an illumination module, and the illumination module performs visible light illumination on the sensitive material film covered on the surface of the sensor carrier.

The preparation method based on the indium oxide nanowire can be used for preparing one-dimensional In with the diameter of 50 nm-100 nm₂O₃A nanowire formed by one-dimensional In₂O₃The nanowires cover the outer surface of the sensor carrier because of the one-dimensional In₂O₃The nanowire has large specific surface area, is favorable for gas adsorption, and accelerates NO₂The reaction of the gas and the gas sensitive material improves the sensitivity and the reaction speed of the sensor, thereby shortening the reaction time of the gas sensor; in-containing prepared based on the technical scheme of the invention₂O₃Nanowire NO₂Gas sensors, operable at room temperature, for NO₂The detection is carried out, and NO is greatly expanded₂Working scenes of the gas sensor; meanwhile, the gas sensor prepared in the technical scheme of the invention works in the environment of visible light, and the visible light can further shorten the recovery time of the gas sensor after reaction; the sensor in the technical scheme of the invention can be manufactured by taking the existing commercially available tubular gas sensor as a carrier, and the device has the advantages of simple process, small volume and suitability for mass production.

Drawings

FIG. 1 shows In prepared by the indium oxide nanowire preparation method according to the present invention₂O₃SEM topography of the nanowires;

FIG. 2 shows In prepared by the indium oxide nanowire preparation method according to the present invention₂O₃TEM image of the nanowires;

FIG. 3 shows In prepared by the indium oxide nanowire preparation method according to the present invention₂O₃XRD pattern of the nanowires;

FIG. 4 shows In-based In the present invention₂O₃NO produced by nanowire₂The structure of the sensor is shown schematically;

FIG. 5 shows In-based In the present invention₂O₃NO produced by nanowire₂Sensor for 5ppm NO at different working temperatures₂The sensitivity of (c);

FIG. 6 shows In-based In the present invention₂O₃NO produced by nanowire₂Sensor for 5ppm NO under different illumination conditions₂The response-recovery curve of (a);

FIG. 7 shows In-based In the present invention₂O₃NO produced by nanowire₂Sensor device sensitivity-NO at room temperature₂Concentration profile.

Detailed Description

The embodiment of the preparation method of the indium oxide nanowire comprises the following steps:

a 1: 0.36g of indium nitrate hydrate (In (NO) was weighed out₃)₃.4.5H₂O) and 5-6 ml of N, N-Dimethylformamide (DMF) were placed in a 20ml tapeCovering a glass bottle, and then stirring for 10-20 min until indium nitrate is completely dissolved to obtain a first mixed solution;

a 2: weighing 1.0-1.2 g of polyvinylpyrrolidone (PVP) and putting into the first mixed solution, stirring at room temperature for 10-20 min to finally obtain a transparent and uniform viscous solution, and recording as: a second mixed solution;

a 3: preparing a 10ml syringe, wherein the needle head of the syringe is a special needle head for electrostatic spinning;

the inner diameter of the special electrostatic spinning needle is 0.41mm, and the outer diameter is 0.71 mm;

the propelling speed of the injector is 0.1-0.6 ml/h, the voltage is set to be 5-20 kv, the receiving distance is set to be 10-20 cm, and the environmental humidity is controlled to be 10-50% RH;

a 4: preparing a receiving roller, wherein a tin foil paper is arranged on the receiving roller and is used for non-woven fabric films; transferring the second solution prepared in the step 2 into an injector for electrostatic spinning;

a 6: obtaining enough electrostatic spinning after about 2-4 h, stopping, taking down the non-woven fabric membrane, and calcining in a muffle furnace; setting the temperature rise rate of the muffle furnace to be 2-10 ℃/min, raising the temperature to 600-900 ℃, and then preserving the temperature for 2-3 h; naturally cooling at a certain temperature to obtain In₂O₃A nanowire powder sample; in₂O₃In contained In nanowire powder sample₂O₃The diameter of the nanowire is 50 nm-100 nm.

In prepared based on indium oxide nanowire preparation method₂O₃Nanowires, with particular reference to figures 1, 2, 3. Hundreds of thousands of In can be seen In the graphs (a) - (c) of FIG. 1₂O₃The nanowires are interwoven and stacked together, have uniform diameters of about 50-100 nm, and as is clear from the higher-order graph of graph (d), each single nanowire is composed of fine grains and is tightly combined together. As shown In FIG. 2, In can be seen In the low-magnification TEM image₂O₃The shape and configuration of the nanowire are consistent with the SEM observation result, and In is observed through a high-power TEM image₂O₃The component crystal particles of the nanowires are clearer; as shown in FIG. 3, no other characteristic peak appeared in the XRD spectrum, indicating thatThe sample was relatively pure indium oxide.

The indium oxide nanowire prepared based on the technical scheme of the invention is used for preparing NO₂A specific method of a gas sensor, comprising the steps of:

b 1: preparing a sensor carrier having a gas sensor function; the sensor carrier can be an existing commercial gas sensor;

b 2: in is mixed with₂O₃The method comprises the following steps of (1) mixing a nano wire powder sample and deionized water according to the ratio of 2-5: 1, grinding the mixture to obtain a mixture containing In₂O₃A third mixed solution of nanowire paste;

b 3: reforming a sensor carrier: uniformly and completely covering the third mixed solution on the outer surface of the sensor carrier to form a sensitive material film of 10-30 microns; the minimum coverage requirement is the outer surface of the electrode, i.e. at least ensuring In₂O₃The nanowire completely covers the sensing electrode;

b 4: baking the sensor carrier under an infrared lamp for 20-30 min, and calcining the sensor carrier coated with the sensitive material film at 150-200 ℃ for 2-3 h to obtain room temperature NO based on the indium oxide nanowire₂A sensor; ensuring In by baking₂O₃The nanowires can be firmly attached to the surface of the sensor carrier.

The gas sensor manufactured by the technical scheme of the invention can work at room temperature, but when a faster reaction speed and a faster recovery speed after reaction are needed in some occasions, the sensor can be integrally heated by the heating wire, so that the sensitivity, the reaction speed and the recovery speed of the sensor are further improved, wherein the integration mode of the heating wire further comprises the following steps:

b 5: passing the nickel-cadmium alloy coil through the inside of the sensor carrier to be used as a heating wire, and obtaining a semi-finished sensor product;

b 6: welding and packaging the semi-finished product of the sensor according to a general indirectly heated gas sensitive element to obtain the room temperature NO based on the indium oxide nanowire with the heating function₂A sensor;

the gas sensor can be heated and heated by heating the electrode heating wire, and the gas sensor can be heated during reaction or recovery after reaction, so that better sensor sensitivity, higher reaction speed and recovery speed after reaction can be obtained.

Indium oxide nanowires manufactured based on the technical scheme of the invention, and NO containing the indium oxide nanowires manufactured by the method₂The gas sensor, with particular reference to fig. 4, is fabricated using a commercially available gas sensor as a carrier. It includes: al (Al)₂O₃The ceramic tube 1, the sensing electrode in this embodiment is provided on Al₂O₃Two sensing ring-shaped gold electrodes 3 on the outer periphery of the ceramic tube are composed of In₂O₃The sensitive material film 2 formed by the nano wires is uniformly covered outside the carrier, and the sensitive material film 2 is uniformly covered on the outer surface of the annular gold electrode 3 for sensing at least; in specific practice, Al₂O₃The outer surfaces of the ceramic tube 1 and the annular gold electrode 3 are covered with sensitive material films 2; a platinum wire 4 is welded on the annular gold electrode 3 for sensing, and the platinum wire is conductive and is used for conducting the resistance of the device to a monitored instrument; the heating wire 5 penetrates through Al₂O₃A body of a ceramic tube; the heating wire is realized based on a nickel-cadmium alloy coil and is used for heating the gas sensor when needed; al (Al)₂O₃The length of the ceramic tube is 4-4.5 mm, the inner diameter is 0.8-1.0 mm, the outer diameter is 1.2-1.5 mm, and the width of the annular gold electrode is 0.5-1.0 mm; the resistance of the nickel-cadmium alloy coil is 30-40 omega.

NO containing indium oxide nanowire in the technical scheme of the patent₂The gas sensor also comprises an illumination module (not shown), and the illumination module is used for illuminating the annular gold electrode 3 and Al₂O₃The sensitive material film 2 covered on the outer surface of the ceramic tube 1 is irradiated by visible light; under certain non-illumination use environments, if the recovery speed after faster reaction is required and the sensor is not suitable to be heated by the heating wires, visible light can be introduced through the illumination module; under irradiation of visible light, In₂O₃Electron-hole pairs, holes (h), are generated in the nanofibers⁺) Can reach the surface and react with NO₂ ⁻，O₂ ⁻，O⁻Recombine to return the trapped electrons to In₂O₃Performing the following steps; the unpaired electrons of the electron-hole pairs are refilled In₂O₃Leading to a narrowing of the depletion layer width; that is, visible light adsorbs In₂O₃NO on the surface of nanofibers₂The gas ensures that the resistance value of the sensor is quickly restored to the initial value, and the recovery speed of the sensor after reaction is improved; in the specific implementation, the illumination module only needs to use the existing lighting device capable of emitting visible light.

At room temperature with NO produced according to the invention₂Sensor as NO under test₂The gas sensor was tested as follows.

Storing target gas NO by two steel cylinders respectively₂And dry air, two steel cylinders connect a gas flowmeter; by adjusting the gas flow rates of the two cylinders, the high concentration of NO in the cylinders can be adjusted₂Diluting to a specific concentration; to be tested for NO₂The gas sensor is connected into the built test circuit and is arranged in the gas cylinder. Introducing a certain concentration of NO₂And recording the change curve of the sensor resistance through computer-side test software, and calculating the response value and the response/recovery time of the sensor resistance.

Confirming tested NO by adjusting the working temperature of the steel cylinder₂Gas sensor for NO at different temperatures₂The sensitivity of (c); as a result of the test, as shown in FIG. 5, it can be seen that NO was tested₂The optimum working temperature of the gas sensor is 25 ℃, and the gas sensitive element is aligned with 5ppm NO₂Has a sensitivity of 740, sensitivity being defined as the sensor NO₂Resistance in gases R_gTo the resistance Ra in air.

By adjusting NO₂Gas concentration, confirmation of NO2 gas sensor sensitivity and NO tested₂A relationship of gas concentration; the test results are shown in FIG. 7 when tested for NO₂Gas sensor with sensitivity accompanied by NO at 25 deg.C₂The increase in concentration is increased and it can be easily found that the examples are capable of detecting 10 ppb of NO₂Gas, which represents its very low detection limit;therefore, NO manufactured based on the technical scheme of the patent₂The gas sensor can work in a wide gas concentration range, namely, the gas sensor has good detection sensitivity.

To confirm the NO tested₂The speed of the gas sensor after reaction is recovered, and the following comparison is carried out in the recovery process:

(1) in the recovery process, visible light with the wavelength of about 380-800 nm is introduced to irradiate the tested NO₂An outer surface of the gas sensor;

(2) in the recovery process, visible light is not introduced;

the results are shown in FIG. 6, NO at 25 ℃ working temperature₂Both of them showed a faster response speed and higher sensitivity at a concentration of 5ppm, but the recovery times differed greatly; process (2) without introduction of visible light, the recovery time at room temperature is long, about 1000s, marked as comparative example in fig. 6; the recovery process (1) with the introduction of visible light showed a shorter recovery time of only 20s, marked as an example in fig. 6.