CN110836913A - Iron-doped porous indium oxide gas-sensitive material and preparation method and application thereof - Google Patents
Iron-doped porous indium oxide gas-sensitive material and preparation method and application thereof Download PDFInfo
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Abstract
The present invention relates to NO2The technical field of gas sensitive materials, in particular to an iron-doped porous indium oxide gas sensitive material and a preparation method and application thereof. The gas-sensitive material consists of a matrix phase and a doping phase, wherein the matrix phase is porous indium oxide and is a monodisperse porous nanorod, and the porous nanorod consists of particles with a pore channel structure; the doped phase is iron ions, and the doped phase is doped in the matrix phase crystal lattice in the form of the iron ions. The iron-doped porous indium oxide gas-sensitive material effectively improves the effect of pure indium oxide as the gas-sensitive material on low-concentration NO2Low sensitivity, poor selectivity and long response recovery time. Through tests, the gas sensitive element prepared by adopting the gas sensitive material is specific to NO2The gas has excellent selectivity and low concentration of NO2The gas has high sensitivity, and the working temperature is reduced to be below 100 ℃, so that the power requirement on instrument equipment is obviously reduced.
Description
Technical Field
The present invention relates to NO2The technical field of gas sensitive materials, in particular to an iron-doped porous indium oxide gas sensitive material and a preparation method and application thereof.
Background
The information disclosed in this background of the invention is only for enhancement of understanding of the general background of the invention and is not necessarily to be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Nitrogen dioxide (NO)2) The gas is a reddish-brown, noxious gas with irritant gases, and one of the main pollutants in the atmosphere. NO2The gas is a typical pollution gas in industrial waste gas and domestic waste gas, has high chemical activity and strong corrosivity, can react with moisture or hydrocarbon in the air, is a main source for forming secondary pollutants such as acid rain, photochemical smog, haze and the like, and seriously threatens the health of people and living environment where people live. According to the data of the American Association of government Industrial health (ACGIH) and the occupational safety and health administration (US), it has been shown that people are allowed to be exposed to NO2Threshold limit in gas is 3ppm with 1ppm NO2The exposure time in the gas is not more than 15 min. Therefore, the gas-sensitive sensing material with high sensitivity and selectivity is designed for detecting low-concentration NO2Gas is of great significance.
The porous indium oxide material has an adjustable pore channel structure, a high specific surface area and a strong ion exchange performance, is beneficial to the reaction of reactants at an active site, and shows a great application prospect in the field of gas detection, so that the porous indium oxide material is widely applied to the field of gas-sensitive sensing. However, a number of studies have shown that: in alone2O3The gas-sensitive property of the gas-sensitive material is controlled by factors such as the morphology, the structure, the crystal form, the specific surface area, the energy band structure and the like of the material, and the gas-sensitive material has the defects of low sensitivity, poor selectivity and the like during gas detection. Meanwhile, the present inventors found that: some porous In exists2O3The temperature required by the gas sensitive material is too high, for example, the working temperature of the metal element doped indium oxide gas sensitive material proposed by danni, etc. of the university of measurement in china is up to more than 300 ℃ (see document 1); zhangeng et al of Tai Yuan Physician university propose that a noble metal modified indium oxide microstructure gas-sensitive material has good sensitivity and response recovery speed to test gas at about 200 ℃ (see document 2); the nano indium oxide and the composite material provided by Chenyang, etc. of the second university of Shanghai industry can effectively improve the gas-sensitive performance at low temperature, but the nano indium oxide and the composite material have NO gas-sensitive performance2The working temperature is still above 150 ℃ during gas detection (see document 3). These gas sensor operating temperatures of up to several hundred degrees celsius place extremely high demands on the power of the instrumentation, thereby limiting the practical application of indium oxide in the field of gas sensors.
The prior documents are as follows:
document 1: dennie, the research on the preparation of metal element doped mesoporous indium oxide and the gas-sensitive performance thereof [ D ], university of Chinese measurement, 2016.
Document 2: zhangmeng, preparation and modification of indium oxide microstructure and its sensitivity study [ D ], university of Tai Ching Kong, 2017.
Document 3: chenyang, nanometer In2O3Preparation of and its composition and gas-sensitive property research [ D]Shanghai second university of industry, 2018.
Disclosure of Invention
Aiming at the defects of low sensitivity, poor selectivity, high working temperature and the like of indium oxide for detecting low-concentration nitrogen dioxide gas, the invention aims to provide an iron-doped porous indium oxide gas-sensitive material, a preparation method and application thereof2The gas has the advantages of high sensitivity, excellent selectivity and the like at low temperature, and has high response recovery speed.
The first object of the present invention: an iron-doped porous indium oxide gas-sensitive material is provided.
The second object of the present invention: provides a preparation method of an iron-doped porous indium oxide gas-sensitive material.
The third object of the present invention: application of the iron-doped porous indium oxide gas-sensitive material is provided.
In order to achieve the purpose, the invention adopts the following technical means:
the invention discloses an iron-doped porous indium oxide gas-sensitive material which comprises a matrix phase and a doping phase, wherein the matrix phase is porous indium oxide and is a monodisperse porous nanorod, and the porous nanorod is composed of particles with a pore channel structure; the doped phase is iron ions, and the doped phase is doped in the matrix phase crystal lattice in the form of the iron ions.
One of the characteristics of the iron-doped porous indium oxide gas-sensitive material is as follows: the gas-sensitive material is a monodisperse porous nanorod and has extremely high specific surface area; the high specific surface area provides more active sites for the adsorption of gas on the surface of the material, and the porous structure provides rich channels for the diffusion of the gas on the surface of the material, which is beneficial to improving In2O3Material pair NO2Sensitivity of the gas and speed of response recovery.
The iron-doped porous indium oxide gas-sensitive material of the invention is characterized by comprising the following two parts: in the porous indium oxide gas-sensitive material doped with iron, the doping of metallic iron (Fe) can improve the oxygen vacancy concentration on the surface of the porous indium oxide material, improve the electrical property of the material at low temperature and increase NO2The adsorption quantity of the gas on the surface of the material at low temperature and the quantity of molecules participating in gas-sensitive reaction; on the other hand, doping elements are used as a surface catalyst and an adsorbent, so that the surface activity of the material at low temperature is improved, and In is increased2O3Material for NO at low temperature2Sensitivity of gas, thereby realizing In2O3Material for NO at low temperature2And (4) detecting the gas.
Secondly, the invention discloses a preparation method of an iron-doped porous indium oxide gas-sensitive material, which comprises the following steps:
(1) dissolving a matrix raw material, a doping phase raw material and an organic ligand in an organic solvent, and preparing an indium-iron coordination polymer through solvothermal reaction; the matrix raw material is indium salt, and the doped phase raw material is ferric salt;
(2) and calcining the indium-iron coordination polymer to obtain the indium-iron coordination polymer.
Finally, the invention discloses application of the iron-doped porous indium oxide gas-sensitive material in gas detection.
Compared with the prior art, the invention has the following beneficial effects:
(1) the iron-doped porous indium oxide gas-sensitive material effectively improves the effect of pure indium oxide as the gas-sensitive material on low-concentration NO2Low sensitivity, poor selectivity and long response recovery time. Through tests, the gas sensitive element prepared by adopting the gas sensitive material is specific to NO2The gas has excellent selectivity and low concentration of NO2The gas has high sensitivity, and the working temperature is reduced to be below 80 ℃, so that the power requirement on instrument equipment is obviously reduced.
(2) The iron-doped porous indium oxide gas-sensitive material is a nanorod with uniform size and single dispersion, has good dispersibility, and can avoid the problem of uneven smearing caused by agglomeration in the preparation process of a gas-sensitive element.
(3) The preparation method of the invention is to synthesize the gas sensitive material in one step, because the matrix phase and the doping are generated under the solvothermal condition, and because the proportion of the matrix raw material is higher than that of the doping phase raw material, the matrix phase becomes the main body during crystallization, the gas sensitive material is directly synthesized by a one-step method, and the preparation method is simple and time-saving in operation and has better effect.
(4) The invention provides a safe and effective method for preparing NO2The preparation method of the gas iron-doped porous indium oxide gas-sensitive element is safe and effective, the required equipment is simple and easy to operate, the process parameters are convenient to control, the use cost of raw materials and instrument equipment is low, and the like.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
Fig. 1 is a Scanning Electron Microscope (SEM) photograph of an iron-doped porous indium oxide gas-sensitive material prepared in example 1 of the present invention.
FIG. 2 is a Transmission Electron Microscope (TEM) photograph of the Fe-doped porous indium oxide gas-sensitive material prepared in example 1 of the present invention.
FIG. 3 is a BET specific surface area spectrum of the iron-doped porous indium oxide gas-sensitive material prepared in example 1 of the present invention.
FIG. 4 is an energy dispersion spectrum of the iron-doped porous indium oxide gas-sensitive material prepared in example 1 of the present invention.
FIG. 5 is an XRD pattern of an iron-doped porous indium oxide gas sensitive material prepared in example 1 of the present invention and an iron-undoped porous indium oxide gas sensitive material prepared in a comparative example.
FIG. 6 is the O1s peak energy spectrum of X-ray photoelectron diffraction of the iron-doped porous indium oxide gas-sensitive material prepared in example 1.
Fig. 7 is an X-ray photoelectron diffraction O1s peak energy spectrum of porous iron-undoped indium oxide prepared according to a comparative example of the present invention.
Fig. 8 is a schematic view of an indirectly heated sensor in an embodiment of the present invention. In the figure, 1 represents an alumina ceramic substrate; 2 represents the gold electrode tested; 3, 4 represents the platinum electrode tested; 5 represents a heating electrode; 6, 7 represents a Ni-Cr electrode; and 8 represents a gas sensitive material layer.
FIG. 9 shows the iron-doped porous indium oxide nanorods prepared according to examples 1 and 2 of the present invention and the non-iron-doped porous indium oxide prepared according to the comparative example at 80 ℃ to 2ppm NO2Response value of gas.
FIG. 10 shows that the iron-doped porous indium oxide gas-sensitive material prepared in example 1 of the present invention has NO at different concentrations2Gas sensitivity performance test chart at 80 ℃.
FIG. 11 is a bar graph of the response of the Fe-doped porous indium oxide gas sensing material prepared in example 1 of the present invention and the Fe-undoped porous indium oxide prepared in the comparative example to 2ppm of different gases at 80 ℃.
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
As mentioned above, In alone2O3The gas-sensitive property of the gas-sensitive material is controlled by the factors of the shape, structure, crystal form, specific surface area, energy band structure and the like of the material, and the gas-sensitive material is in low-concentration NO2The gas detection has the defects of low sensitivity, poor selectivity and the like. Meanwhile, some porous In exists2O3The temperature required for the operation of the gas sensitive material is too high. Therefore, the invention provides an iron-doped porous indium oxide gas-sensitive material and a preparation method thereof.
In some typical embodiments, the doping amount of the iron ions is 0.5 to 20 mol%; preferably 3 to 20 mol%, more preferably 5 to 10 mol%. For the iron-doped porous indium oxide gas-sensitive material, with the increase of iron doping content, the increase of oxygen vacancies on the surface of the gas-sensitive material is promoted, which is beneficial to NO2The gas is adsorbed on the surface of the material and participates in gas-sensitive reaction, so that NO of the material is improved2The sensitivity of gas, however, excessive iron doping causes the destruction of the indium oxide lattice structure, which is not beneficial to the optimization of the electrical performance, so that the electron transfer efficiency is reduced, and the improvement of the gas-sensitive performance is inhibited.
In some typical embodiments, the porous nanorods have a diameter of 0.5-3 μm and a length of 1-9 μm.
In some exemplary embodiments, the molar ratio of the dopant phase feedstock to the matrix phase feedstock is 0.5 to 20 mol%; preferably 3 to 10 mol%, and the test results show that when the doping amount of iron ions is selected within the above range, the resulting gas-sensitive materialFor low concentration of NO2Has better sensitivity.
In some typical embodiments, the organic ligand is 0.5 to 2 times the molar amount of the matrix material.
In some exemplary embodiments, the indium salt includes one or more of indium chloride, indium nitrate, and indium sulfate.
In some exemplary embodiments, the iron salt comprises one or more of ferric nitrate, ferric chloride, and ferric acetylacetonate.
In some typical embodiments, the organic ligand is terephthalic acid, and during the solvothermal reaction, an octahedral group (InO) with indium and iron as the center4(OH)2、FeO4(OH)2) The indium-iron coordination polymer with hexagonal nanometer structure with nanorods is grown by coupling terephthalic acid as organic chains.
In some typical embodiments, the organic solvent is N, N-dimethylacetamide. The addition amount of the solvent can be enough to fully dissolve the matrix raw material, the doping phase raw material and the organic ligand.
In some typical embodiments, the solvothermal process is at a temperature of 80 to 150 ℃ for a reaction time of 5 to 20 min.
In some exemplary embodiments, the calcination temperature is 450 ℃ and 540 ℃ and the calcination time is 1.5-2.5 h.
In some typical embodiments, the prepared iron-doped porous indium oxide gas-sensitive material is used for preparing NO2A gas sensor; comprises a ceramic substrate 1 and a gas sensitive material layer 8; the gas-sensitive material layer 8 is attached to the surface of the ceramic substrate 1.
In some exemplary embodiments, the NO is2The preparation method of the gas sensor comprises the following steps: coating the gas-sensitive material slurry on the surface of a ceramic substrate, and drying to obtain NO2A gas sensor.
In some exemplary embodiments, the gas sensitive material slurry is prepared by: and adding the iron-doped porous indium oxide gas-sensitive material into a mixed solution of ethyl cellulose and terpineol, and uniformly stirring to obtain the iron-doped porous indium oxide gas-sensitive material.
Optionally, the ratio of ethylcellulose to terpineol is from 1:5 to 10, preferably 1: 9.
In some exemplary embodiments, the NO is2The gas sensor is used for preparing an indirectly heated sensor, the NO2One surface of the gas sensor is provided with a test electrode and a platinum wire, NO2The other surface of the gas sensor is provided with a heating electrode and a Ni-Cr electrode.
Furthermore, the ceramic substrate is made of any one of alumina and silicon oxide; the test electrode and the heating electrode are made of gold.
In order to make the technical solutions of the present invention more clearly understood by those skilled in the art, the present invention will be further described with reference to the drawings and the detailed description of the specification.
First embodimentThe preparation method of the iron-doped porous indium oxide gas-sensitive material comprises the following steps:
(1) 0.39g of the base material In (NO)3)3·4.5H2O, 0.0175g doping phase raw material Fe (C)15H21O6) 0.18g of organic ligand H2Adding BDC into 75ml of organic solvent N, N-dimethylacetamide and stirring until the BDC is dissolved;
(2) and (2) placing the clear liquid stirred in the step (1) in an oil bath at 100 ℃ for reaction for 10min to enable the raw materials to generate coordination polymerization reaction to obtain an indium-iron coordination polymer, then centrifugally separating the polymer, washing the polymer for 5 times by using methanol, and drying the polymer in an oven at 80 ℃.
(3) And calcining the dried indium-iron coordination polymer in a muffle furnace at 500 ℃ for 2h to obtain the powdery iron-doped porous indium oxide gas-sensitive material.
Second embodimentThe preparation method of the iron-doped porous indium oxide gas-sensitive material is the same as the preparation method of the example 1, and is characterized in that: the molar ratio of the doping phase to the matrix material in step (1) is 3 mol%, 10 mol%, 20 mol%.
Third embodimentThe preparation method of the iron-doped porous indium oxide gas-sensitive material comprises the following steps:
(1) 0.39g of base material indium chloride and 0.0175g of doping phase raw material Fe (NO)3)30.09g of organic ligand H2Adding BDC into 75ml of organic solvent N, N-dimethylacetamide and stirring until the BDC is dissolved;
(2) and (2) placing the clear liquid stirred in the step (1) in an oil bath at the temperature of 80 ℃ for reaction for 20min to enable the raw materials to generate coordination polymerization reaction to obtain an indium-iron coordination polymer, then centrifugally separating the polymer, washing the polymer for 5 times by using methanol, and drying the polymer in an oven at the temperature of 80 ℃.
(3) And calcining the dried indium-iron coordination polymer in a muffle furnace at 450 ℃ for 2.5h to obtain the powdery iron-doped porous indium oxide gas-sensitive material.
Fourth embodimentThe preparation method of the iron-doped porous indium oxide gas-sensitive material comprises the following steps:
(1) 0.39g of a base material In2(SO3)30.0175g of doping phase raw material FeCl30.36g of organic ligand H2Adding BDC into 75ml of organic solvent N, N-dimethylacetamide and stirring until the BDC is dissolved;
(2) and (2) placing the clear liquid stirred in the step (1) in an oil bath at 150 ℃ for reaction for 5min to enable the raw materials to generate coordination polymerization reaction to obtain an indium-iron coordination polymer, then centrifugally separating the polymer, washing the polymer for 5 times by using methanol, and drying the polymer in an oven at 80 ℃.
(3) And calcining the dried coordination polymer of indium and iron in a muffle furnace at 540 ℃ for 1.5h to obtain the powdery iron-doped porous indium oxide gas-sensitive material.
Comparative exampleThe preparation method of the porous indium oxide gas-sensitive material without doped phase comprises the following steps:
(1) 0.39g of the base material In (NO)3)3·4.5H2O, 0.18g of organic ligand H2Adding BDC into 75ml of organic solvent N, N-dimethylacetamide and stirring until the BDC is dissolved;
(2) and (2) placing the clear liquid stirred in the step (1) in an oil bath at 100 ℃ for reaction for 10min to enable the raw materials to generate coordination polymerization reaction to obtain an indium-iron coordination polymer, then centrifugally separating the polymer, washing the polymer for 5 times by using methanol, and drying the polymer in an oven at 80 ℃.
(3) And calcining the dried indium-iron coordination polymer in a muffle furnace at 500 ℃ for 2h to obtain the powdery iron-doped porous indium oxide gas-sensitive material.
And (3) performance testing:
FIG. 1 is an SEM image of the Fe-doped porous indium oxide gas-sensitive material prepared in example 1, and it can be seen that the doped gas-sensitive material is monodisperse nanorods, and the nanorods have a diameter of about 0.5-3 μm and a length of about 1-9 μm.
Fig. 2 is a TEM image of the iron-doped porous indium oxide gas-sensitive material prepared in example 1, and it can be seen that the iron-doped porous indium oxide nanorods are porous nanorods composed of small particles, and exhibit a rich pore channel structure.
FIG. 3 is the BET specific surface area result of the iron-doped porous indium oxide gas-sensitive material prepared in example 1, which shows that the specific surface area of the iron-doped porous indium oxide is as high as 52.7m2(ii) in terms of/g. Compared with a bulk indium oxide gas-sensitive material, the indium oxide gas-sensitive material has a large specific surface area, provides a favorable channel and an active surface for gas adsorption and desorption, and is favorable for improving the sensitivity and the response recovery speed of the material.
Fig. 4 is an energy dispersion spectrum of the iron-doped porous indium oxide gas-sensitive material prepared In example 1, and the result shows that the iron-doped porous indium oxide nanorod obtained by solvothermal and then calcining contains three elements, namely In, Fe and O, and the three elements are uniformly distributed on the surface of the material.
FIG. 5 is an X-ray spectrum of the Fe-doped porous indium oxide gas-sensitive material prepared in example 1 and the porous indium oxide nanorod prepared in comparative example 1, and it can be seen from the diagram that after the porous indium oxide is doped, no other crystal phase appears, but the diffraction peaks of the materials have a tendency of high angle shift; in addition, after the porous indium oxide is doped, the intensity of the diffraction peak is reduced and the peak width is widened. The above results show that metallic iron successfully enters the interior of the crystal lattice of the pure porous indium oxide in the form of ions, and the oxygen vacancy concentration on the surface of the material is regulated.
Fig. 6 and 7 are O1s peak energy spectrograms of X-ray photoelectron diffraction of the iron-doped porous indium oxide gas-sensitive material prepared in example 1 and the iron-undoped porous indium oxide prepared in the comparative example, respectively, and it can be seen that after the metal iron is doped to the pure porous indium oxide, the oxygen vacancy concentration on the surface is increased from 24.6% to 25.4%, and the significant increase of the oxygen vacancy concentration is favorable for the adsorption of nitrogen dioxide gas on the surface of the gas-sensitive material, and can improve the sensitivity of the gas-sensitive material to nitrogen dioxide gas.
The iron-doped porous indium oxide gas-sensitive material prepared in the examples 1 and 2 is prepared into a gas-sensitive element, and the preparation method comprises the following steps:
1. preparing a gas sensor:
(1) adding the powdery iron-doped porous indium oxide gas-sensitive material prepared by the method in the embodiment 1 into a mixed solution (mass ratio of 1:9) of ethyl cellulose and terpineol, and uniformly stirring to obtain gas-sensitive material slurry, wherein the mass ratio of the gas-sensitive material to the mixed solution is 1: 4.
(2) And (3) smearing the gas-sensitive material slurry obtained in the step (1) on the surface of the alumina ceramic substrate 1 to form a gas-sensitive material layer 8, and drying to obtain the gas-sensitive element.
2. Preparing an indirectly heated sensor: the structure schematic diagram is shown in fig. 8, wherein the right drawing is the back of the left drawing, the alumina ceramic substrate 1 is used as a carrier, gold electrodes coated on two surfaces of the alumina ceramic substrate 1 are respectively a test electrode 2 and a heating electrode 5, tested platinum electrodes 3 and 4 and heated Ni-Cr electrodes 6 and 7 are led out, and the surface of the alumina ceramic substrate 1 coated with the test electrode 2 is coated with a gas-sensitive material layer 8.
Meanwhile, the porous indium oxide which is not doped with iron and prepared in the comparative example is also prepared into the gas sensitive elements according to the method, the five groups of gas sensitive elements are assembled into an indirectly heated sensor, and 2ppm NO is added at 80 DEG C2The gas-sensitive performance of the porous indium oxide is tested under the gas condition, and the detection result is shown in fig. 9, so that the gas-sensitive performance of the porous indium oxide doped with iron is changed to a certain extent after the concentration of the doped phase is changed, but the porous indium oxide still shows high sensitivity compared with pure indium oxide, and particularly when the doped phase is 5 mol%, the response value of the porous indium oxide doped with iron is 9 times that of the porous indium oxide doped with iron.
FIG. 10 shows that the sensors prepared from the Fe-doped porous indium oxide gas-sensitive material prepared in example 1 have different NO concentrations at 80 ℃2Response value of gas. It can be seen from the figure that at the working temperature of 80 ℃, the response value of the material shows a trend of steadily increasing along with the increase of the gas concentration. When NO is present2At a gas concentration of 2ppm, the iron-doped porous indium oxide nanorods show a high response value (82), which is the ratio of the resistance of the material in a gas environment to its resistance in air, and a fast response recovery time (75/60 s); meanwhile, the iron-doped porous indium oxide gas-sensitive material disclosed by the invention can reduce the working temperature of the sensor to be below 100 ℃, and can still treat low-concentration NO2The gas has excellent sensitivity; in addition, other test results show that the iron-doped porous indium oxide gas-sensitive material prepared by the method can still realize the purpose of low-concentration NO at the working temperature of as low as 80 DEG C2Good detection of gases.
FIG. 11 is a graph showing the response of sensors made of the iron-doped porous indium oxide gas sensing material prepared in example 1 and the iron-undoped porous indium oxide prepared in comparative example to 2ppm of different gases at 80 ℃; it can be seen that the porous indium oxide gas sensitive material doped with iron has NO sensitivity to NO relative to the porous indium oxide not doped with iron2The gas shows a higher response value (82), which is that the pure porous indium oxide nano-rods have 2ppm NO2The gas response value (9) is 9 times. The response value to other gases is close to 1, which means almost NO response, and this shows that the iron-doped porous indium oxide gas-sensitive material significantly improves the NO response of pure porous indium oxide nanorods2Gas selectivity and exhibits excellent selectivity.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The iron-doped porous indium oxide gas-sensitive material is characterized by consisting of a matrix phase and a doping phase, wherein the matrix phase is porous indium oxide and is monodisperse porous nanorods, and the porous nanorods consist of particles with pore channel structures; the doped phase is iron ions, and the doped phase is doped in the matrix phase crystal lattice in the form of the iron ions.
2. The iron-doped porous indium oxide gas-sensitive material of claim 1, wherein the doping amount of the iron ions is 0.5 to 20 mol%; preferably 3 to 10 mol%.
3. The iron-doped porous indium oxide gas-sensitive material of claim 1, wherein the porous nanorods have a diameter of 0.5-3 μm and a length of 1-9 μm.
4. A preparation method of an iron-doped porous indium oxide gas-sensitive material is characterized by comprising the following steps:
(1) dissolving a matrix raw material, a doping phase raw material and an organic ligand in an organic solvent, and preparing an indium-iron coordination polymer through solvothermal reaction; the matrix raw material is indium salt, and the doped phase raw material is ferric salt;
(2) and calcining the indium-iron coordination polymer to obtain the indium-iron coordination polymer.
5. The method for preparing the iron-doped porous indium oxide gas-sensitive material of claim 4, wherein the molar ratio of the doped phase raw material to the matrix phase raw material is 0.5-20 mol%; preferably 3 to 20 mol%, more preferably 5 to 10 mol%;
alternatively, the organic ligand is 0.5 to 2 times the molar amount of the matrix material.
6. The method for preparing the iron-doped porous indium oxide gas-sensitive material of claim 4, wherein the indium salt comprises one or more of indium chloride, indium nitrate and indium sulfate;
or the ferric salt comprises one or more of ferric nitrate, ferric chloride and ferric acetylacetonate;
or, the organic ligand is terephthalic acid;
or the organic solvent is N, N-dimethylacetamide.
7. The method for preparing the iron-doped porous indium oxide gas-sensitive material according to claim 4, wherein the solvothermal method is carried out at a temperature of 80-150 ℃ for a reaction time of 5-20 min;
alternatively, in some exemplary embodiments, the calcination temperature is 450-.
8. NO (nitric oxide)2The gas sensor is characterized by comprising a ceramic substrate and a gas-sensitive material layer; the gas-sensitive material layer is formed by attaching the iron-doped porous indium oxide gas-sensitive material prepared by the method of any one of claims 1 to 3 and/or the iron-doped porous indium oxide gas-sensitive material prepared by the method of any one of claims 4 to 7 on the surface of a ceramic substrate; preferably, the material on the ceramic substrate includes any one of alumina and silica.
9. The NO of claim 82Gas sensor, characterized in that said NO2The preparation method of the gas sensor comprises the following steps: coating the gas-sensitive material slurry on the surface of a ceramic substrate, and drying to obtain NO2A gas sensor;
preferably, the preparation method of the gas-sensitive material slurry comprises the following steps: adding the iron-doped porous indium oxide gas-sensitive material into a mixed solution of ethyl cellulose and terpineol, and uniformly stirring to obtain the iron-doped porous indium oxide gas-sensitive material;
preferably, the ratio of ethyl cellulose to terpineol is 1:5-10, preferably 1: 9.
10. NO according to claim 8 or 92The application of the gas sensor in gas detection.
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