CN116337951A - NiO-based formaldehyde gas sensor and preparation method thereof - Google Patents

NiO-based formaldehyde gas sensor and preparation method thereof Download PDF

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CN116337951A
CN116337951A CN202310319265.7A CN202310319265A CN116337951A CN 116337951 A CN116337951 A CN 116337951A CN 202310319265 A CN202310319265 A CN 202310319265A CN 116337951 A CN116337951 A CN 116337951A
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sensitive material
nio
material film
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formaldehyde gas
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蒯贇
叶晓冬
李磊
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Anhui Yuanchen Material Research And Design Institute Co ltd
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    • 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
    • G—PHYSICS
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    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
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    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
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Abstract

The invention discloses a NiO-based formaldehyde gas sensor and a preparation method thereof, wherein the preparation method comprises the following steps: uniformly mixing nickel nitrate hexahydrate, aluminum nitrate hexahydrate and water to obtain a precursor solution; dripping the precursor solution on the surface of the glass sheet subjected to ozone ultraviolet cleaning until the surface is completely covered, and baking to obtain a sensitive material film; transferring the prepared sensitive material film into absolute ethyl alcohol to enable the sensitive material film to float on the liquid level, then fishing out the sensitive material film by using a ceramic tube device to obtain the ceramic tube device with the sensitive material film attached to the surface, and baking; annealing the ceramic tube device containing the sensitive material film obtained after baking to obtain a sensing device with the surface containing metal oxide; and (3) soldering the sensing device on a ceramic base, and carrying out metal encapsulation to obtain the NiO-based formaldehyde gas sensor. The method provided by the invention is simple to prepare, and the obtained sensor has high formaldehyde sensitivity and rapid response recovery.

Description

NiO-based formaldehyde gas sensor and preparation method thereof
Technical Field
The invention relates to the technical field of micro-nano sensing application, in particular to a NiO-based formaldehyde gas sensor and a preparation method thereof.
Background
Along with the continuous improvement of the living standard of people, the interior decoration is increasingly diversified, and a plurality of novel materials and coatings are continuously developed and widely applied to the home decoration industry, so that the novel materials and coatings become an important source of indoor air pollution. At present, most people spend nearly 80% -90% of the time indoors, the indoor air quality is good or bad, the human health is directly influenced, the U.S. Environmental Protection Agency (EPA) has already classified indoor air pollution as a fourth environmental health hazard except for air pollution, toxic chemicals in production workshops and water pollution, and Canadian environmental sanitation organization research results also show that 68% of diseases of human beings are caused by indoor air pollution, and the incidence rate of the diseases is rising year by year.
According to incomplete statistics, the types of pollutants in indoor air are up to thousands, and mainly comprise formaldehyde, benzene, toluene, dimethylbenzene, volatile Organic Compounds (VOCs), ammonia, nitrogen oxides, carbon monoxide, sulfur dioxide, radioactive gas radon and the like, and the symptoms such as headache, nausea and vomiting, dyspnea and the like can be caused by long-time intake of the gases by a human body, and even more, the pollutants can be caused to be cancerogenic, and irrecoverable injuries can be caused to people with weak resistance such as pregnant women, infants and the like. Formaldehyde (HCHO) is a colorless, toxic gas with a strong pungent odor, has a relative air density of 1.06, is readily soluble in water, alcohols and ethers, and its 35% to 40% aqueous solution is commonly known as formalin. The formaldehyde source in the room is mainly from chemical products in daily life such as building materials, decorations and the like, and in addition, the formaldehyde can be from cosmetics, cleaning agents, pesticides, disinfectants, preservatives, printing ink, paper, textile fibers and the like, and the formaldehyde source is extremely wide. The maximum allowable concentration of formaldehyde in room air is 0.08mg/m specified by the sanitary Standard of formaldehyde in room air (GB/T16127-1995) 3 The average value in 1h indoor is 0.10mg/m 3 Public health standards prescribe that the maximum allowable concentration of formaldehyde in the air is 0.12mg/m 3 Namely, the highest concentration limit value of formaldehyde in the living room is 0.065ppm.
The current formaldehyde gas detection methods are numerous and can be roughly classified into spectrophotometry, chromatography and sensors. Spectrophotometry is a qualitative analysis method based on different formation of electromagnetic radiation absorption degrees by substances, and mainly can be divided into a phenol reagent method, a phloroglucinol method, an AHMT method, an acetylacetone method, a color-changing acid method, fuchsin-sulfurous acid, a catalytic photometry method and the like, but the various detection methods have the defects of complex operation process, poor stability and long detection time, and cannot meet the requirements of on-site rapid detection of formaldehyde. The chromatography uses the difference of distribution coefficients of different substances in different phases, and the substances in a flowing relatively fixed phase are eluted, so that the separation result is finally achieved, but the chromatography has higher requirements on detection instruments, longer derivatization time and complex operation process, and cannot meet the indoor rapid detection requirement. Therefore, metal oxide semiconductor-based gas sensors have become a major research hotspot in formaldehyde monitoring methods.
Bell et al found that semiconductor germanium has a difference in resistivity after exposure to different gases in the 50 s of the last century. In 1967, shaver et al were then creatively combining noble metals with semiconductor materials, resulting in a great improvement in sensor performance. SnO was found by Taguchi et al 2 The metal oxide has the advantages of better sensitivity, stability and the like, and more semiconductor materials such as ZnO and In 2 O 3 The microstructure and reaction mechanism of the materials are gradually clear along with the deep research, namely, the conductivity or resistance of the sensitive material of each metal oxide changes after the metal oxide contacts gas, and finally, the sensitive material is output by an electric signal to reflect the concentration of target gas.
There is a lot of research on formaldehyde sensors. SnO based on coaxial heterostructure is described in the Chinese patent application publication No. CN105603713A 2 The preparation method of the formaldehyde sensor of the ZnO nano composite fiber material comprises the steps of taking PVP as a solvent, synthesizing tin salt, ethanol and DMF, and obtaining fibrous SnO by electrostatic spinning and calcination 2 Then mixing the material with zinc acetate, and obtaining the gas-sensitive material with the special structure through water bath, wherein the gas-sensitive material can respond to 10ppm formaldehyde after being coated on the surface of a ceramic tube sensor, but the method has more technical processes and more complex procedures; WO doped with noble metal is disclosed in the Chinese patent application publication No. CN107561133A 3 Formaldehyde sensor by measuring a formaldehyde content in a sheet form WO 3 The noble metal is loaded, the response speed of formaldehyde is greatly improved, and the work is reducedThe temperature is higher, but the detection concentration is higher, so that the indoor alarm requirement cannot be met; the Chinese patent application publication No. CN107879381A discloses a preparation method of a formaldehyde sensor based on a NiO nanomaterial modified by Sn atoms, which comprises the steps of synthesizing the NiO material by a hydrothermal method, mixing a Sn salt solution of the NiO material with NiO powder, generating vacancies at low temperature, calcining to obtain the special material, and having good response degree to formaldehyde, but the preparation process is complicated, involves high-low temperature treatment, and is not suitable for practical production.
Disclosure of Invention
The invention aims to solve the technical problem of providing the formaldehyde gas sensor which is simple in preparation method, extremely low in detection limit, high in sensitivity and rapid in response recovery.
The invention solves the technical problems by the following technical means:
a preparation method of a NiO-based formaldehyde gas sensor comprises the following steps:
s1, uniformly mixing nickel nitrate hexahydrate, aluminum nitrate hexahydrate and water to obtain a precursor solution;
s2, the precursor solution is taken and dripped on the surface of the glass sheet which is cleaned by ozone and ultraviolet until the surface is completely covered, and a sensitive material film is obtained after baking;
s3, transferring the prepared sensitive material film into absolute ethyl alcohol to enable the sensitive material film to float on the liquid surface, then, using a ceramic tube device to scoop up the sensitive material film, and obtaining the ceramic tube device with the sensitive material film attached to the surface, and baking;
s4, annealing the ceramic tube device containing the sensitive material film obtained after baking in the step S3 to obtain a sensing device with the surface containing metal oxide;
and S5, soldering the sensing device on the ceramic base, and carrying out metal encapsulation to obtain the NiO-based formaldehyde gas sensor.
The beneficial effects are that: the preparation method comprises the steps of firstly preparing a gas-sensitive material precursor solution, then further preparing a sensitive material film, coating the gas-sensitive material film on the surface of a ceramic tube device, calcining and annealing the coated ceramic tube device, welding the annealed ceramic tube device on a ceramic base, and carrying out metal encapsulation to complete the preparation of the formaldehyde gas sensor, wherein the preparation method is simple in process, and the obtained sensor has high formaldehyde detection sensitivity, short response recovery time and extremely low detection limit.
Preferably, in S1, the weight ratio of the nickel nitrate hexahydrate to the aluminum nitrate hexahydrate is 5.27-8.43:1-2.9.
Preferably, in S1, the concentration of nickel nitrate hexahydrate in the precursor solution is 0.1-0.17g/ml; the concentration of the aluminum nitrate hexahydrate is 0.02-0.06g/ml.
Preferably, in S2, the baking means baking with an infrared lamp until the surface has no significant moisture.
Preferably, in S3, the ceramic tube device is an ozone ultraviolet cleaned ceramic tube device.
Preferably, in S3, the baking temperature is 65-90 ℃ and the baking time is 10-45min.
Preferably, in S4, the annealing is performed at a temperature of 400-450 ℃ for a time of 1.5-2 hours.
Preferably, in S2, the precursor solution is used in an amount of 0.35-0.36mL/cm on the surface of the glass sheet 2 。
Preferably, in S2, the glass sheet subjected to ozone-ultraviolet cleaning refers to a glass sheet obtained by cleaning the glass sheet in an ozone-ultraviolet cleaning machine.
The invention also provides a NiO-based formaldehyde gas sensor, which is prepared by adopting the preparation method of the NiO-based formaldehyde gas sensor.
The invention has the advantages that:
the invention firstly prepares the pre-solution of the gas sensitive material, then further prepares the sensitive material film, then coats the gas sensitive material film on the surface of the ceramic tube device, calcines and anneals the coated ceramic tube device, then welds the annealed ceramic tube device on a ceramic base, and carries out metal encapsulation to complete the preparation of the formaldehyde gas sensor, the process is simple, and the obtained sensor has high formaldehyde detection sensitivity, extremely low detection limit and short response recovery time, and can alarm formaldehyde exceeding standard in time.
Drawings
FIG. 1 is a graph showing the sensitivity change of the sensor prepared in example 1 of the present invention to formaldehyde;
FIG. 2 is a response recovery curve of the sensor prepared in example 1 of the present invention to 10ppm formaldehyde.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described in the following in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The test materials, reagents and the like used in the examples described below are commercially available unless otherwise specified.
Those of skill in the art, without any particular mention of the techniques or conditions, may follow the techniques or conditions described in the literature in this field or follow the product specifications.
Example 1
A preparation method of a NiO-based formaldehyde gas sensor comprises the following specific steps:
(1) Preparation of a Material precursor solution
7.27g of nickel nitrate hexahydrate and 1.88g of aluminum nitrate hexahydrate are placed in a beaker, 30mL of deionized water is added for dissolution, the beaker containing the mixed solution is sealed and placed in an ultrasonic cleaner, and ultrasonic treatment is carried out for 15 min. After the end, transferring the mixed solution in the beaker into a 50mL volumetric flask, rinsing the beaker with deionized water for three times, pouring the rinse solution into the flask, adding water into a dropper to fix the volume to a scale mark, and obtaining the required precursor solution.
(2) Preparation of sensor sensitive material film
And taking 7mL of the precursor solution, continuously dripping the precursor solution onto the surface of a glass slide (the size is 76mm multiplied by 26 mm) which is cleaned by ozone and ultraviolet for 10min until the surface is completely covered, and then transferring the glass slide to an infrared lamp for baking until no obvious moisture is present on the surface (incomplete drying), thereby obtaining the required sensor sensitive material film.
(3) Coating of sensitive material films
Transferring the prepared sensitive material film into absolute ethyl alcohol to enable the sensitive material film to float on a liquid surface, clamping a ceramic tube device subjected to ozone ultraviolet cleaning by using tweezers, extending below the liquid surface until the sensitive material film is below the liquid surface, then upwards moving the ceramic tube device to enable the sensitive material film to be attached to the surface of the ceramic tube device, obtaining the ceramic tube device with the sensitive material film attached to the surface, and then placing the ceramic tube device into an oven to be baked for 30 minutes at the constant temperature of 80 ℃ to enable the sensitive material film to be completely covered on the surface of the device.
(4) Device annealing treatment
And (3) placing the ceramic tube device containing the sensitive material film in a muffle furnace, and annealing for 2 hours at the set temperature of 400 ℃ to obtain the sensing device with the surface containing the metal oxide.
(5) Ceramic base soldering and packaging
And soldering the prepared sensing device on a ceramic base, and carrying out metal encapsulation to prepare the NiO-based formaldehyde gas sensor.
Example 2
A preparation method of a NiO-based formaldehyde gas sensor comprises the following specific steps:
(1) Preparation of a Material precursor solution
5.27g of nickel nitrate hexahydrate and 1.04g of aluminum nitrate hexahydrate are placed in a beaker, 25mL of deionized water is added for dissolution, the beaker containing the mixed solution is sealed and then placed in an ultrasonic cleaner, and ultrasonic treatment is carried out for 18 min. After the end, transferring the mixed solution in the beaker into a 50mL volumetric flask, rinsing the beaker with deionized water for three times, pouring the rinse solution into the flask, adding water into a dropper to fix the volume to a scale mark, and obtaining the required precursor solution.
(2) Preparation of sensor sensitive material film
And taking 7mL of the precursor solution, continuously dripping the precursor solution onto the surface of a glass slide (the size is 76mm multiplied by 26 mm) which is cleaned by ozone and ultraviolet for 10min until the surface is completely covered, and then transferring the glass slide to an infrared lamp for baking until no obvious moisture is present on the surface (incomplete drying), thereby obtaining the required sensor sensitive material film.
(3) Coating of sensitive material films
Transferring the prepared sensitive material film into absolute ethyl alcohol to enable the sensitive material film to float on a liquid surface, clamping a ceramic tube device subjected to ozone ultraviolet cleaning by using tweezers, extending below the liquid surface until the sensitive material film is below the liquid surface, then upwards moving the ceramic tube device to enable the sensitive material film to be attached to the surface of the ceramic tube device, obtaining the ceramic tube device with the sensitive material film attached to the surface, and then placing the ceramic tube device into an oven to be baked at the constant temperature of 65 ℃ for 45 minutes to enable the sensitive material film to be completely covered on the surface of the device.
(4) Device annealing treatment
And (3) placing the ceramic tube device containing the sensitive material film in a muffle furnace, and annealing for 2 hours at the set temperature of 400 ℃ to obtain the sensing device with the surface containing the metal oxide.
(5) Ceramic base soldering and packaging
And soldering the prepared sensing device on a ceramic base, and carrying out metal encapsulation to prepare the NiO-based formaldehyde gas sensor.
Example 3
A preparation method of a NiO-based formaldehyde gas sensor comprises the following specific steps:
(1) Preparation of a Material precursor solution
8.43g of nickel nitrate hexahydrate and 2.9g of aluminum nitrate hexahydrate are placed in a beaker, 40mL of deionized water is added for dissolution, the beaker containing the mixed solution is sealed and then placed in an ultrasonic cleaner, and ultrasonic treatment is carried out for 10 min. After the end, transferring the mixed solution in the beaker into a 50mL volumetric flask, rinsing the beaker with deionized water for three times, pouring the rinse solution into the flask, adding water into a dropper to fix the volume to a scale mark, and obtaining the required precursor solution.
(2) Preparation of sensor sensitive material film
And taking 7mL of the precursor solution, continuously dripping the precursor solution onto the surface of a glass slide (the size is 76mm multiplied by 26 mm) washed by ultraviolet ozone for 10min until the surface is completely covered, and then transferring the glass slide to an infrared lamp for baking until no obvious moisture is present on the surface (incomplete drying), thereby obtaining the required sensor sensitive material film.
(3) Coating of sensitive material films
Transferring the prepared sensitive material film into absolute ethyl alcohol to enable the sensitive material film to float on a liquid surface, clamping a ceramic tube device subjected to ozone ultraviolet cleaning by using tweezers, extending below the liquid surface until the material film is below the liquid surface, then upwards moving the ceramic tube device to enable the sensitive material film to be attached to the surface of the ceramic tube device, obtaining the ceramic tube device with the sensitive material film attached to the surface, and then placing the ceramic tube device into an oven to be baked for 10 minutes at the constant temperature of 90 ℃ to enable the sensitive material film to be completely covered on the surface of the device.
(4) Device annealing treatment
And (3) placing the ceramic tube device containing the sensitive material film in a muffle furnace, and annealing at the set temperature of 450 ℃ for 1.5h to obtain the sensing device with the surface containing the metal oxide.
(5) Ceramic base soldering and packaging
And soldering the prepared sensing device on a ceramic base, and carrying out metal encapsulation to prepare the NiO-based formaldehyde gas sensor.
Comparative example 1
The preparation method of the formaldehyde gas sensor is different from the embodiment 1 only in that: in (2), the slide is an ultrasonically cleaned slide, not an ozone ultraviolet cleaned slide.
Comparative example 2
The preparation method of the formaldehyde gas sensor is different from the embodiment 1 only in that: in the step (3), the prepared sensitive material film is transferred into absolute ethyl alcohol to float on the liquid surface, then a tweezer is used for clamping the ceramic tube device which is cleaned by ozone and ultraviolet, the ceramic tube device stretches below the liquid surface until the sensitive material film is below the liquid surface, and then the ceramic tube device with the sensitive material film attached on the surface is obtained by upwards moving the ceramic tube device.
Comparative example 3
A method for manufacturing a formaldehyde gas sensor, which is different from example 1 in that: in (1), 7g of tin tetrachloride pentahydrate was used instead of 7.27g of nickel nitrate hexahydrate, and aluminum nitrate hexahydrate was used in an amount of 1.25g.
Comparative example 4
A method for manufacturing a formaldehyde gas sensor, which is different from example 1 in that: in (1), 2.975g of zinc nitrate hexahydrate was used in place of 7.27g of nickel nitrate hexahydrate, and 0.36g of copper nitrate trihydrate was used in place of 1.88g of aluminum nitrate hexahydrate.
Comparative example 5
A method for manufacturing a formaldehyde gas sensor, which is different from example 1 in that: in (1), 7.01g of tin tetrachloride pentahydrate is used for replacing 7.27g of nickel nitrate hexahydrate, 1.08g of nickel nitrate hexahydrate is used for replacing 1.88g of aluminum nitrate hexahydrate, and meanwhile, a proper amount of hexachloroplatinic acid is added into the mixed solution before volume fixing, so that the mass of Pt element in the mixed solution is 3wt% of Sn in the tin tetrachloride.
Device gas sensitive performance test
The formaldehyde gas sensors prepared in examples 1 to 3 and comparative examples 1 to 5 were subjected to gas-sensitive tests, and the test platform was a source-surface-level multichannel gas-sensitive test platform (SMP-4) developed by the national academy of sciences of fertilizer-composition materials science solid physics. The platform uses a multimeter (Agilent U3606A), a direct current power supply (U8002A) to provide a voltage source and perform signal acquisition; in the test, gas was injected into the test chamber through an injector from an inlet, and two rotating fans of 300rpm were symmetrically distributed at the inlet for rapid mixing of the gas in the chamber. When the device encounters gas, the resistance of the device changes, and the voltage value in the universal meter changes. The test platform uses LabVIEW software to set and regulate parameters, and the test is carried out under the environment conditions of relative humidity of 60% RH and room temperature of 25 ℃. The results of the test are shown in table 1.
TABLE 1 sensitivity (ratio of resistances) test results for the sensing devices of examples 1-3, comparative examples 1-5
Figure BDA0004151092700000071
As can be seen from the results in table 1, the formaldehyde sensor prepared based on the thin film process can generate good response to formaldehyde gas with extremely low concentration, and the proper amount of adjustment of the material formula does not have great influence on the performance of the sensor; meanwhile, the key effect of ultraviolet ozone cleaning in the whole film manufacturing process can be observed, and the mode can effectively remove impurities on the surfaces of the glass slide and the ceramic tube, and obviously improve the hydrophilicity of each medium, so that the film material is compact and dispersed on the surface; the drying process of the surface moisture of the device is important before annealing, otherwise, the direct annealing can vaporize the residual moisture on the surface of the device, so that the film structure is damaged; finally, it can be seen that the NiO semiconductor material is more suitable for the low concentration formaldehyde response under the process, and the effect is very poor when being changed into other materials.
As can be seen from fig. 1 and 2, the sensor has good response to formaldehyde gas with various concentrations, and shows good linear relation, thus ensuring the accuracy of concentration output; meanwhile, in the response recovery test, the response recovery of the sensor to formaldehyde is very rapid, so that the early warning requirement can be met in practical application.
The invention firstly prepares the pre-solution of the gas sensitive material, then further prepares the sensitive material film, then coats the gas sensitive material film on the surface of the ceramic tube device, and places the coated ceramic tube device in a muffle furnace for calcination and annealing, then welds the annealed ceramic tube on a ceramic base, and carries out metal encapsulation to finish the preparation of the formaldehyde gas sensor.
The above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (9)

1. The preparation method of the NiO-based formaldehyde gas sensor is characterized by comprising the following steps of:
s1, uniformly mixing nickel nitrate hexahydrate, aluminum nitrate hexahydrate and water to obtain a precursor solution;
s2, the precursor solution is taken and dripped on the surface of the glass sheet which is cleaned by ozone and ultraviolet until the surface is completely covered, and a sensitive material film is obtained after baking;
s3, transferring the prepared sensitive material film into absolute ethyl alcohol to enable the sensitive material film to float on the liquid surface, then, using a ceramic tube device to scoop up the sensitive material film, and obtaining the ceramic tube device with the sensitive material film attached to the surface, and baking;
s4, annealing the ceramic tube device containing the sensitive material film obtained after baking in the step S3 to obtain a sensing device with the surface containing metal oxide;
and S5, soldering the sensing device on the ceramic base, and carrying out metal encapsulation to obtain the NiO-based formaldehyde gas sensor.
2. The method for preparing the NiO-based formaldehyde gas sensor according to claim 1, wherein: in S1, the weight ratio of the nickel nitrate hexahydrate to the aluminum nitrate hexahydrate is 5.27-8.43:1-2.9.
3. The method for preparing the NiO-based formaldehyde gas sensor according to claim 1, wherein: in S1, the concentration of nickel nitrate hexahydrate in the precursor solution is 0.1-0.17g/ml; the concentration of the aluminum nitrate hexahydrate is 0.02-0.06g/ml.
4. The method for preparing the NiO-based formaldehyde gas sensor according to claim 1, wherein: in S2, the baking means baking with an infrared lamp until no significant moisture is present on the surface.
5. The method for preparing the NiO-based formaldehyde gas sensor according to claim 1, wherein: in S3, the ceramic tube device is a ceramic tube device cleaned by ozone ultraviolet.
6. The method for preparing the NiO-based formaldehyde gas sensor according to claim 1, wherein: in S3, the baking temperature is 65-90 ℃ and the baking time is 10-45min.
7. The method for preparing the NiO-based formaldehyde gas sensor according to claim 1, wherein: in S4, the annealing temperature is 400-450 ℃ and the annealing time is 1.5-2h.
8. The method for producing a NiO-based formaldehyde gas sensor according to any one of claims 1 to 7, wherein: in S2, the precursor solution is used at the surface of the glass sheet in an amount of 0.35-0.36mL/cm 2 。
9. A NiO-based formaldehyde gas sensor is characterized in that: the preparation method of the NiO-based formaldehyde gas sensor according to any one of claims 1 to 8.
CN202310319265.7A 2023-03-28 2023-03-28 NiO-based formaldehyde gas sensor and preparation method thereof Pending CN116337951A (en)

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