CN108680609B - Room-temperature ammonia gas sensor taking p-type delafossite structure oxide as sensitive material and preparation method thereof - Google Patents
Room-temperature ammonia gas sensor taking p-type delafossite structure oxide as sensitive material and preparation method thereof Download PDFInfo
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- CN108680609B CN108680609B CN201810212137.1A CN201810212137A CN108680609B CN 108680609 B CN108680609 B CN 108680609B CN 201810212137 A CN201810212137 A CN 201810212137A CN 108680609 B CN108680609 B CN 108680609B
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- 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
Abstract
The invention discloses a room-temperature ammonia gas sensor taking p-type delafossite structure oxide as a sensitive material and a preparation method thereof. Firstly processing p-type delafossite structure AgAlO2As a sensitive material of the ammonia sensor, a resistance type room temperature ammonia sensor with excellent performance is constructed. The sensor fully utilizes the advantages of high sensitivity, low cost, simple device, easy integration and easy realization of on-site continuous detection of semiconductor resistance type sensing materials and AgAlO2The method has the characteristics of high selectivity to ammonia gas at room temperature, constructs a resistance-type sensor which can work at room temperature, is sensitive to ammonia gas (the lower detection limit can reach the million level), has good selectivity and good stability, is economic and environment-friendly, finds a good sensitive material for the ammonia gas sensor, and opens up a new application field for p-type wide band gap delafossite structure oxides.
Description
Technical Field
The invention belongs to the technical field of sensitive materials and sensors, and particularly relates to a room-temperature ammonia gas sensor taking p-type delafossite structure oxides as sensitive materials and a preparation method thereof.
Background
Ammonia has wide application in the fields of chemical industry, light industry, chemical fertilizers, pharmacy, synthetic fibers and the like, is often used for manufacturing ammonia water, nitrogenous fertilizers (urea, ammonium bicarbonate and the like) and the like, and also contains nitrogen-containing inorganic salts, organic matter intermediates and the like which all need to directly take ammonia as a raw material. Ammonia exists in the form of a gas at normal temperature and pressure, and is called ammonia gas. Ammonia gas is a colorless gas with a strong pungent odor, has irritating and burning effects on human skin, eyes and mucous membranes of respiratory organs, and can cause lung swelling and death if inhaled too much. The metal semiconductor material is the material which is firstly applied to the ammonia gas sensor, mainly depends on the conductivity change before and after contacting ammonia gas for detection, and has the advantages of low cost, high sensitivity, portability and the like. However, the existing ammonia gas sensor has the defects of poor selectivity, long response-recovery time, need of working at high temperature (> 150 ℃) and the like.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides the novel ammonia gas sensor which has high response sensitivity to ammonia gas, good selectivity, strong stability, short response-recovery time and works at room temperature and the preparation method thereof.
In order to achieve the purpose, the invention adopts the following technical scheme:
a room temperature ammonia gas sensor taking p-type delafossite structure oxide as a sensitive material comprises a gas sensitive material composite substrate, wherein the gas sensitive material is uniformly coated on the surface of the substrate, and the gas sensitive material component is p-type delafossite structure AgAlO2And the coating thickness of the gas sensitive material is 500nm-100 mu m.
The p-type delafossite structure AgAlO2The particle size of the nanoparticles is in the range of 20nm to 600 nm.
The substrate is Al with Pt, Au or Al electrodes2O3A substrate.
A preparation method of a room-temperature ammonia gas sensor taking p-type delafossite structure oxide as a sensitive material comprises the following steps:
step one, preparing p-type delafossite structure AgAlO2Nano-particles:
mixing Al (NO)3)3·9H2O and AgNO3Dissolving in deionized water, adding NaOH after dissolving, pouring the solution into a polytetrafluoroethylene lining with the filling degree of 60-70%, and putting the autoclave into an oven with 190-Reacting at 230 ℃ for 24-64 hours, cooling to room temperature, taking out, washing silvery white powder with 1M/L dilute ammonia water, 1M/L dilute nitric acid and deionized water, and drying for later use;
step two, preparing gas-sensitive material slurry:
the p-type delafossite structure AgAlO2Mixing the nano particles with absolute ethyl alcohol, ethyl cellulose and terpineol, and uniformly stirring by magnetic force to obtain gas-sensitive material slurry;
step three, preparing an ammonia gas sensor:
coating the prepared gas-sensitive material slurry on a substrate to form a gas-sensitive film, wherein the coating thickness of the gas-sensitive material is 1-100 mu m; sintering the gas-sensitive film at the temperature of 300-500 ℃ for 1-4 hours to finally obtain the AgAlO2An ammonia gas sensor.
Wherein Al (NO) in the first step3)3·9H2O、AgNO3And NaOH in a molar ratio of 1: (0.8-1.5): (2-6).
Wherein, the p-type delafossite structure AgAlO in the step two2The weight ratio of the powder to the ethyl cellulose to the terpineol is 1: (0.5-2): (0.5-2).
Wherein, the gas-sensitive film sintering atmosphere in the third step can be air, vacuum or N2And Ar inert atmosphere.
The ammonia gas sensor is a resistance type semiconductor gas sensor, mainly detects according to resistance change before and after an element adsorbs gas, and utilizes the gas to be detected to carry out physical or chemical adsorption and desorption on a sensitive material to cause the change of electrical properties such as material resistance and the like so as to achieve the detection purpose. The working temperature of the ammonia gas sensor is in the room temperature range; the sensor resistance changes under the environment of flowing air and ammonia gas with air as background to generate a sensor signal; the real-time monitoring signal of the sensor is the change of the resistance value of the sensor.
Compared with the prior art, the invention has the following advantages:
1. the ammonia gas sensor has the advantages of simple manufacturing process and convenient operation.
2. P-type copper-iron of the inventionOre structure AgAlO2The response of the nano-particles to ammonia gas has the advantages of high sensitivity (the lower detection limit can reach a million level), short response recovery time and good stability; meanwhile, a good sensitive material is found for the ammonia gas sensor, and a new application field is opened up for the p-type wide band gap delafossite structure oxide.
3. The sensor prepared by the invention has good selectivity to ammonia gas, is insensitive to other common gases (such as methanol, toluene, acetone, absolute ethyl alcohol and the like), and can quickly and effectively detect ammonia gas in a plurality of mixed gases.
4. The ammonia gas sensor prepared by the invention works at room temperature, does not need a heating device and a temperature measuring device, saves an additional structure, and avoids the aging or damage of the whole device under long-time high-temperature work.
Drawings
FIG. 1 shows AgAlO of p-type delafossite structure in example 12An X-ray diffraction pattern of the nanoparticles;
FIG. 2 shows AgAlO of p-type delafossite structure in example 12Scanning electron micrographs of nanoparticles;
FIG. 3 shows AgAlO of p-type delafossite structure in example 12X-ray photoelectron spectroscopy of the nanoparticles;
FIG. 4 is a graph showing the response of the ammonia gas sensor prepared in example 1 of the present invention to the change in resistance of 100ppm of several volatile gases at room temperature;
FIG. 5 shows the ammonia gas sensor of the present invention at room temperature for 20-100 ppm NH3Resistance change response map of (a); ra is the resistance value of the sensor in the air, and Rg is the resistance value of the sensor in the measured gas.
Detailed Description
The invention is described in detail below with reference to the figures and the embodiments. The following examples are only illustrative of the present invention, and the scope of the present invention shall include the full contents of the claims, not limited to the examples.
Example 1
Room temperature ammonia gas sensor with p-type delafossite structure oxide as sensitive material, bagThe gas sensitive material is uniformly coated on the surface of the substrate, the coating thickness of the gas sensitive material is 10 mu m, and the gas sensitive material is p-type delafossite structure AgAlO2Nanoparticles having a particle diameter of 200nm to 500 nm;
the preparation method comprises the following steps:
step one, preparing p-type delafossite structure AgAlO2Nano-particles: 0.015mol of Al (NO)3)3·9H2O and 0.015mol AgNO3Dissolving in 70 ml deionized water, adding 2.4 g NaOH after dissolving, pouring the solution into 100ml polytetrafluoroethylene lining, putting the autoclave into an oven for reacting at 210 ℃ for 64 hours, cooling to room temperature, taking out, washing silvery white powder with 1M/L dilute ammonia water, 1M/L dilute nitric acid and deionized water, and drying for later use;
step two, preparing gas-sensitive material slurry: 0.2 g p type delafossite structure AgAlO2Mixing the nano particles with 3 ml of absolute ethyl alcohol, 0.05g M9 ethyl cellulose and 0.2 g of terpineol, and uniformly stirring by magnetic force to obtain gas-sensitive material slurry;
step three, preparing an ammonia gas sensor: and uniformly coating the prepared gas-sensitive material slurry on a substrate to form a gas-sensitive film, wherein the coating thickness of the gas-sensitive material is 4 micrometers. Sintering the gas-sensitive film for 4 hours at 400 ℃ to finally obtain the AgAlO2An ammonia gas sensor.
P-type delafossite structure AgAlO obtained in the example2The nanoparticles, characterized by X-ray diffraction and scanning electron microscopy, gave the results shown in figures 1, 2 and 3 of the accompanying drawings.
Example 2
A room temperature ammonia gas sensor taking p-type delafossite structure oxide as a sensitive material comprises a gas sensitive material and a substrate, wherein the gas sensitive material is uniformly coated on the surface of the substrate, the coating thickness of the gas sensitive material is 50 mu m, and the gas sensitive material is p-type delafossite structure AgAlO2Nanoparticles having a particle diameter of 1 μm to 3 μm;
the preparation method comprises the following steps:
step one, preparing p-type delafossite structure AgAlO2Nano-particles: 0.015mol of Al (NO)3)3·9H2O and 0.01575mol AgNO3Dissolving in 70 ml deionized water, adding 3 g NaOH after dissolving, pouring the solution into 100ml polytetrafluoroethylene lining, putting the autoclave into an oven for reacting at 220 ℃ for 64 hours, cooling to room temperature, taking out, washing silvery white powder with 1M/L dilute ammonia water, 1M/L dilute nitric acid and deionized water, and drying for later use;
step two, preparing gas-sensitive material slurry: 0.2 g p type delafossite structure AgAlO2Mixing the nano particles with 2 ml of absolute ethyl alcohol, 0.05g M9 ethyl cellulose and 0.2 g of terpineol, and uniformly stirring by magnetic force to obtain gas-sensitive material slurry;
step three, preparing an ammonia gas sensor: and uniformly coating the prepared gas-sensitive material slurry on a substrate to form a gas-sensitive film, wherein the coating thickness of the gas-sensitive material is 50 micrometers. Sintering the gas-sensitive film for 4 hours at 350 ℃ to finally obtain the AgAlO2An ammonia gas sensor.
Example 3
A room temperature ammonia gas sensor taking p-type delafossite structure oxide as a sensitive material comprises a gas sensitive material and a substrate, wherein the gas sensitive material is uniformly coated on the surface of the substrate, the coating thickness of the gas sensitive material is 100 mu m, and the gas sensitive material is p-type delafossite structure AgAlO2Nanoparticles having a particle diameter range of 200nm to 500 nm;
the preparation method comprises the following steps:
step one, preparing p-type delafossite structure AgAlO2Nano-particles: 0.015mol of Al (NO)3)3·9H2O and 0.015mol AgNO3Dissolving in 70 ml deionized water, adding 2.4 g NaOH after dissolving, pouring the solution into 100ml polytetrafluoroethylene lining, putting the autoclave into an oven for reacting at 220 ℃ for 64 hours, cooling to room temperature, taking out, washing silvery white powder with 1M/L dilute ammonia water, 1M/L dilute nitric acid and deionized water, and drying for later use;
step two, preparing gas-sensitive material slurry: 0.3 g p type delafossite structure AgAlO2Mixing the nano particles with 2 ml of absolute ethyl alcohol, 0.05g M9 ethyl cellulose and 0.2 g of terpineol, and uniformly stirring by magnetic force to obtain gas-sensitive material slurry;
step three, preparing an ammonia gas sensor: and uniformly coating the prepared gas-sensitive material slurry on a substrate to form a gas-sensitive film, wherein the coating thickness of the gas-sensitive material is 100 micrometers. Sintering the gas-sensitive film for 4 hours at 500 ℃ to finally obtain the AgAlO2An ammonia gas sensor.
Example 4 Ammonia sensor Performance test
The sensors prepared in examples 1 to 3 were placed in an air environment at room temperature and an ambient air humidity of 35% RH, and NH was then introduced3Gas molecules. Measuring different NH concentrations of the sensor in air and in air as background by a multimeter3The resistance change in the environment is used as the signal of the sensor. An ammonia gas sensor prepared in example 1 is taken as an example and is explained with reference to fig. 4, and fig. 4 shows the prepared sensor for several kinds of volatile gases such as ethanol, methanol, propanol and the like and NH3The resistance response comparison at room temperature can find that the sensor is coupled with NH3Is several times higher than other gases, indicating that the sensor is responsive to NH3The response sensitivity of (2) is high. FIG. 5 shows NH of the prepared sensor at 20-100 ppm3Environmental, changes in sensor resistance. At 100ppm NH3Under the environment, the response time of the sensor is 29s, and the recovery time is 49 s. Compared with other similar sensors, the sensor pair NH of the invention3The response and recovery speed of the system is high.
It should be noted that, according to the above embodiments of the present invention, those skilled in the art can fully implement the full scope of the present invention as defined by the independent claims and the dependent claims, and implement the processes and methods as the above embodiments; and the invention has not been described in detail so as not to obscure the present invention.
The above description is only a part of the embodiments of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
Claims (5)
1. The room-temperature ammonia gas sensor with the p-type delafossite structure oxide as the sensitive material comprises a gas-sensitive material and a substrate, wherein the gas-sensitive material is uniformly coated on the surface of the substrate, and is characterized in that the gas-sensitive material comprises p-type delafossite structure AgAlO2 nanoparticles, and the coating thickness of the gas-sensitive material is 500nm-100 mu m;
the particle size range of the p-type delafossite structure AgAlO2 nanoparticles is 20nm-600 nm;
the substrate is an Al2O3 substrate with Pt, Au or Al electrodes.
2. A preparation method of a room-temperature ammonia gas sensor taking p-type delafossite structure oxide as a sensitive material is characterized by comprising the following steps: step one, preparing p-type delafossite structure AgAlO2 nanoparticles: dissolving Al (NO3) 3.9H 2O and AgNO3 in deionized water, adding NaOH after dissolving, pouring the solution into a polytetrafluoroethylene lining, wherein the filling degree of the lining is 60-70%, placing the high-pressure kettle in an oven for reaction at 230 ℃ for 24-64 hours, cooling to room temperature, taking out, washing silvery white powder with 1M/L dilute ammonia water, 1M/L dilute nitric acid and deionized water, and drying for later use; step two, preparing gas-sensitive material slurry: mixing the p-type delafossite structure AgAlO2 nanoparticles with absolute ethyl alcohol, ethyl cellulose and terpineol, and uniformly stirring by magnetic force to obtain gas-sensitive material slurry; step three, preparing an ammonia gas sensor: coating the prepared gas-sensitive material slurry on a substrate to form a gas-sensitive film, wherein the coating thickness of the gas-sensitive material is 1-100 mu m; sintering the gas-sensitive film at the temperature of 300-500 ℃ for 1-4 hours to finally obtain the AgAlO2 ammonia gas sensor.
3. The method for preparing the room-temperature ammonia gas sensor according to claim 2, wherein the molar ratio of Al (NO3) 3.9H 2O, AgNO3 and NaOH in the first step is 1: (0.8-1.5): (2-6).
4. The method for preparing the room temperature ammonia gas sensor according to claim 2, wherein the weight ratio of the p-type delafossite structure AgAlO2 powder, ethyl cellulose and terpineol in the second step is 1: (0.5-2): (0.5-2).
5. The preparation method of the room temperature ammonia gas sensor as claimed in claim 3, wherein the gas-sensitive thin film sintering atmosphere in the third step can be air, vacuum or N2, Ar inert atmosphere.
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