CN108732207B - Sensitive material for formaldehyde detection and preparation method and application thereof - Google Patents

Abstract

Translated fromChinese

本发明公开一种甲醛检测所用的敏感材料及制备方法和应用，该敏感材料为采用氧化石墨烯为模板使其表面吸附锡配体后，通过热处理获得表面具有介孔结构的还原氧化石墨烯掺杂的氧化锡纳米片，超薄表面及表面具有的介孔结构，使得比表面积达69.8m²∙g^‑1‑105.7m²∙g^‑1，表面具有更多的活性位点。因此，利用其制备的甲醛检测所用的气体传感器中的气敏元件对甲醛具有灵敏度高、对干扰气体选择性好、响应/恢复能力强、检测限低、性能稳定等优点，因此其在甲醛气体传感器中应用时，可有效的提高甲醛气体传感器的灵敏度和选择性。可用于室内外甲醛浓度的检测进行空气质量的评估，从而保障人类的身体健康。

The invention discloses a sensitive material for formaldehyde detection, a preparation method and application thereof. The sensitive material adopts graphene oxide as a template to adsorb tin ligands on its surface, and then obtains a reduced graphene oxide doped with mesoporous structure on the surface through heat treatment. The mixed tin oxide nanosheets, the ultra-thin surface and the mesoporous structure on the surface make the specific surface area reach 69.8m² ∙g^‑1 ‑105.7m² ∙g^‑1 , and the surface has more active sites. Therefore, the gas sensor in the gas sensor for formaldehyde detection prepared by using it has the advantages of high sensitivity to formaldehyde, good selectivity to interfering gases, strong response/recovery ability, low detection limit, and stable performance. When applied in the sensor, the sensitivity and selectivity of the formaldehyde gas sensor can be effectively improved. It can be used for indoor and outdoor formaldehyde concentration detection to evaluate air quality, so as to protect human health.

Description

Sensitive material for formaldehyde detection and preparation method and application thereof

Technical Field

The invention relates to a sensitive material for formaldehyde detection, a preparation method and application thereof, and belongs to the field of semiconductor materials.

Technical Field

Formaldehyde (HCHO) is a carcinogenic Volatile Organic Compound (VOC) in indoor air pollution and poses a serious threat to human health. Is widely used for manufacturing building materials and can be released from household products. Low HCHO levels (1-3ppm) can cause irritation of the nose and eyes, and levels above 15ppm can lead to death. Therefore, an effective HCHO detection method is very important and is healthy and environmentally friendly to the human body. Over the last several decades, a variety of sensors with different sensing mechanisms have been developed for detecting formaldehyde gas. Semiconductor oxide sensors are currently the most widely used class of gas sensors. When the semiconductor oxide sensitive material is used for detecting formaldehyde gas, generally, based on that formaldehyde gas molecules and oxygen species adsorbed on the surface of the sensitive material generate oxidation-reduction reaction, the effective specific surface area of metal oxide can be improved by regulating and controlling a nano structure or surface functionalization, and then the gas-sensitive performance of the metal oxide can be improved. For example, Wang et al SnO prepared by solvothermal methods₂The sensitivity of the microspheres to 100ppm formaldehyde was 38.3. The good gas-sensitive performance of the gas sensor is attributed to three factors of a special spherical structure, a large specific surface area and proper particle size of surface composition particles; successful preparation of SnO by Sun et al using sacrificial template method₂/Zn₂SnO₄Porous hollow microspheres having a sensitivity to 500ppm formaldehyde of 131.6 at 330 ℃; gu et al obtained porous NiO/SnO using a simple chemical solution route coupled with a subsequent calcination process₂Microspheres with a sensitivity of 27.6 to 100ppm formaldehyde at 200 ℃; in addition, various nanostructured metal oxide materials such as Co₃O₄Nanocubes and In₂O₃The use of nanosheets for formaldehyde detection has also been reported.

The novel nano structures have the advantages and disadvantages in the aspects of sensitivity, selectivity and the like, for example, some of the formaldehyde sensors have the advantages of low development cost and simplicity in operation, but have the problems of high working temperature and low sensitivity. Some formaldehyde sensors have low working temperature, even can reach room temperature, and have low detection limit, but have high development cost and a larger distance from practical application.

The formaldehyde sensor is low in price, low in sensitivity and poor in anti-interference capability, and cannot meet the huge market demand of the household environment-friendly industry. Compared with zero-dimensional, one-dimensional and three-dimensional formaldehyde sensitive materials, the two-dimensional oxide sensitive material is concerned by the characteristics of high specific surface area, rich active sites, directional electron conduction and the like.

Reference to the literature

[1] Zhouye, Gauliangjing, Liangjianzei, gas distribution method research by standard gas static volumetric method [ J ] metrology report, 2003,24(3): 236-.

[2] Bear force, King gold, south of the Zhujun, structure and preparation process of semiconductor gas sensitive element [ J ] Meteorological hydrological marine instrument, 2000: 22-24.

Disclosure of Invention

One of the purposes of the present invention is to provide a sensitive material for preparing a gas sensor in a gas sensor for formaldehyde detection, i.e., a sensitive material for formaldehyde detection, in order to solve the technical problems that the high-sensitivity formaldehyde sensor on the market at present is generally too high in price, low in sensitivity, poor in anti-interference capability, and incapable of meeting the huge market demand of the home environment protection industry.

The invention also aims to provide the preparation method of the sensitive material for detecting the formaldehyde, and the preparation method has the advantages of simple preparation steps and suitability for large-scale production.

The gas sensor has the characteristics of low price, high sensitivity to formaldehyde, low working temperature, good selectivity, strong anti-interference capability, quick response recovery and the like.

The fourth purpose of the invention is to provide a preparation method of the sensitive element in the gas sensor for detecting formaldehyde, which has the advantages of simple process, low element price, good repeatability and convenient production and manufacture.

Technical scheme of the invention

The sensitive material for detecting formaldehyde is prepared by the following steps:

①, adding graphene oxide into absolute ethyl alcohol, controlling the power to be 400W and the frequency to be 32KHz, and carrying out ultrasonic treatment for 30min to uniformly disperse the graphene oxide in the absolute ethyl alcohol to obtain a graphene oxide dispersion liquid;

the dosage of the graphene oxide and the absolute ethyl alcohol is as follows: 10-200mg of absolute ethyl alcohol: calculating the ratio of 20-200mL, preferably selecting the graphene oxide: the absolute ethyl alcohol is 100mg:200 mL;

②, adding a tin source into the graphene oxide dispersion liquid obtained in the step ①, stirring for 12-18 hours at the temperature of 10-50 ℃ and the rotating speed of 1000r/min to obtain a mixed solution, wherein the purpose is to enable the tin source to be uniformly adsorbed on the graphene oxide template;

the tin source is tin tetrachloride, dibutyltin dilaurate or tetra-n-butyl stannate; the addition amount of the tin source is calculated according to the volume ratio, and the graphene oxide dispersion liquid is as follows: the tin source is 1: 4-16, preferably 1: 16;

③, controlling the rotation speed of the mixed solution obtained in the step ② at 10000r/min for centrifuging for 15min, washing the obtained precipitate with absolute ethyl alcohol until no tin source exists in the effluent, then controlling the rotation speed at 10000r/min again for centrifuging for 15min, controlling the temperature of the precipitate obtained by centrifuging again at 60 ℃ for drying, and collecting the dried product;

④, placing the dried product obtained in the step ③ into a muffle furnace, heating to 450-500 ℃ at the speed of 1-5 ℃/min, and preferably calcining at 475 ℃ for 2-12h to obtain a sensitive material for formaldehyde detection;

the sensitive material used for detecting the formaldehyde is a reduced graphene oxide doped tin oxide nanosheet with a mesoporous structure on the surface, and the content of the reduced graphene oxide is 0.5-50 wt%, preferably 0.5-3.7 wt%, and the tin oxide is of a tetragonal crystal structure through detection according to the weight percentage; the thickness is 3-15nm, the length is 5-20 μm, the width is 5-15 μm, and the surface is uniformThe mesoporous structure has the mesoporous aperture of 3-10nm and the specific surface area of 69.8m²·g^-1-105.7m²·g^-1。

The preparation process of the sensitive material used for detecting formaldehyde is used for preparing a gas sensitive element in a gas sensor used for detecting formaldehyde and specifically comprises the following steps:

(1) adding deionized water or absolute ethyl alcohol into the obtained sensitive material for formaldehyde detection, and uniformly mixing to obtain pasty slurry;

the dosage of the sensitive material and deionized water or absolute ethyl alcohol used for formaldehyde detection is as follows: calculating the proportion of deionized water or absolute ethyl alcohol of 20mg to 1 ml;

(2) uniformly coating the pasty slurry obtained in the step (1) on the surface of a semiconductor element, controlling the coating thickness to be 0.5-1.5mm, then controlling the temperature to be 60 ℃ for drying, and then controlling the temperature to be 400 ℃ for heat treatment for 2h to obtain the semiconductor element with a dried coating;

the semiconductor element is an alumina ceramic tube;

then, the semiconductor element with the dried coating obtained above and the base material are welded, aged and packaged according to the conventional manufacturing process of the indirectly heated semiconductor gas sensor, specifically refer to the reference^[2]Finally obtaining a gas sensitive element in a gas sensor for detecting formaldehyde;

the base material is a plastic-metal electrode base.

The gas sensitive element in the gas sensor for detecting the formaldehyde can simultaneously meet the requirements of low cost, high sensitivity and high selectivity of the formaldehyde detection, and is expected to be integrated and used in the fields of household appliances, mobile electronic equipment, automobiles and the like.

The invention has the beneficial technical effects

According to the gas sensor for detecting formaldehyde, the sensitive material used for detecting formaldehyde is prepared by taking graphene oxide as a template to absorb the surface of the graphene oxideAfter a tin ligand is attached, the reduced graphene oxide-doped tin oxide nanosheet with the mesoporous structure on the surface is obtained through heat treatment, the content of the reduced graphene oxide in the reduced graphene oxide-doped tin oxide nanosheet with the mesoporous structure is 0.5-50 wt%, preferably 0.5-3.7 wt%, the thickness of the nanosheet is 3-15nm, the length of the nanosheet is 5-20 mu m, the width of the nanosheet is 5-15 mu m, the surface mesopores are uniform, the pore diameter of the mesopores is 3-10nm, and the nanosheet has a large specific surface area which can reach 69.8m due to the mesoporous structure²·g^-1-105.7m²·g^-1The surface of the gas sensor has more active sites, so that the gas sensor in the gas sensor for detecting formaldehyde prepared by the gas sensor has the advantages of high sensitivity, good selectivity to interference gas, strong response/recovery capability, low detection limit, stable performance and the like. The CGS-8 gas sensor test system is used for testing, the gas concentration is 0.25ppm-100ppm, the working temperature can be 40-90 ℃, the sensitivity of the CGS-8 gas sensor to 100ppm formaldehyde reaches 2200, the response time is less than 70s, and the recovery time is less than 90s, so that when the CGS-8 gas sensor is applied to a gas sensor for formaldehyde detection, the sensitivity and the selectivity of the formaldehyde gas sensor can be effectively improved, and the technical problems of low detection sensitivity and selectivity and the like in the prior art are solved. Because the gas sensitive element in the gas sensor used for detecting the formaldehyde has high sensitivity to the formaldehyde and quick response and recovery speed, the characteristics facilitate the integration of the gas sensitive element in the fields of household appliances, mobile electronic equipment, automobiles and the like, and the intelligent monitoring of the formaldehyde is ubiquitous.

Furthermore, according to the gas sensor in the gas sensor for detecting formaldehyde, the graphene oxide is reduced into reduced graphene oxide by a calcination heat treatment process in the preparation process of the sensitive material for detecting formaldehyde, and the reduced graphene oxide is remained in the metal oxide, and trace reduced graphene oxide is used for regulating and controlling the performance of the gas sensitive material semiconductor, so that the working temperature of the formaldehyde sensor can be reduced, and the requirement of low-cost detection is met.

In conclusion, the gas sensitive element in the gas sensor for detecting formaldehyde can simultaneously meet the requirements on low cost and high sensitivity of formaldehyde detection, is expected to be integrated in the fields of household appliances, mobile electronic equipment, automobiles and the like, enables intelligent monitoring of formaldehyde to be ubiquitous, and can generate great economic and social benefits.

Drawings

FIG. 1, X-ray diffraction pattern of the sensitive material used for formaldehyde detection obtained in example 1;

FIG. 2 is a Raman spectrum of a sensitive material used for formaldehyde detection obtained in example 1;

FIG. 3 is an SEM image of a sensitive material used for formaldehyde detection obtained in example 1;

FIG. 4, TEM image of the sensitive material used for formaldehyde detection obtained in example 1;

FIG. 5 is a thermogravimetric plot of the sensitive material used for formaldehyde detection obtained in example 1;

fig. 6 is a graph of the optimum operating temperature of the gas sensor for detecting formaldehyde, which is prepared from the gas-sensitive material for detecting formaldehyde and has a calcination temperature of 475 ℃ in example 1, for 100ppm of formaldehyde aqueous solution;

fig. 7 is a graph showing the selectivity of a gas sensor for detecting formaldehyde, which is prepared from a gas-sensitive material for detecting formaldehyde obtained at a calcination temperature of 475 ℃ in example 1, to interfering gases;

fig. 8 shows the response of the gas sensor for detecting formaldehyde, which is prepared from the gas-sensitive material for detecting formaldehyde obtained at a calcination temperature of 475 ℃ in example 1, to formaldehyde gases of different concentrations;

fig. 9 is a graph showing the linear relationship between the response of the gas sensor for detecting formaldehyde, which is prepared from the gas-sensitive material for detecting formaldehyde obtained at the calcination temperature of 475 ℃ in example 1, and the response of the gas-sensitive element in the gas sensor for detecting formaldehyde, under the conditions of 10ppm, 30ppm, 50ppm and 100 ppm;

FIG. 10 is a graph showing the relationship between the sensitivity to formaldehyde and the formaldehyde concentration at formaldehyde concentrations of 10ppm, 30ppm, 50ppm and 100ppm in a gas sensor for formaldehyde detection, which is manufactured from the sensitive material for formaldehyde detection obtained at calcination temperatures of 450 ℃, 475 ℃ and 500 ℃ for examples 1 to 3, respectively.

Detailed Description

The present invention will be more clearly understood by referring to the accompanying drawings. The invention is of course not limited to this particular embodiment, and general alternatives known to those skilled in the art are also covered by the scope of the invention.

The conventional indirectly heated semiconductor gas sensor manufacturing process described in the embodiments of the present invention is disclosed in the reference^[2]。

The semiconductor element used in each embodiment of the invention is an alumina ceramic tube, belongs to an accessory of an indirectly heated gas sensor, and is purchased from Beijing Elite technology Limited; the used base material is a plastic-metal electrode base, belongs to an accessory of an indirectly heated gas sensor, and is purchased from Beijing Elite technology Limited.

Example 1

The sensitive material for detecting formaldehyde is prepared by the following steps:

①, adding 100mg of graphene oxide into 200ml of absolute ethyl alcohol, controlling the power to be 400W and the frequency to be 32KHz, and carrying out ultrasonic treatment for 30min to uniformly disperse the graphene oxide in the absolute ethyl alcohol to obtain a graphene oxide dispersion liquid;

the dosage of the graphene oxide and the absolute ethyl alcohol is as follows: absolute ethanol 100mg: calculating the proportion of 200 mL;

②, adding 2.47mmol of dibutyltin dilaurate into the graphene oxide dispersion liquid obtained in the step ①, controlling the temperature to be 25 ℃ and the rotating speed to be 1000r/min, and stirring for 16h to obtain a mixed solution, wherein the purpose of the mixed solution is to enable organic tin to be uniformly adsorbed on a graphene oxide template, and the volume ratio of the graphene oxide dispersion liquid to dibutyltin dilaurate is 1: 16;

③, controlling the rotation speed of the mixed solution obtained in the step ② at 10000r/min, centrifuging for 15min, washing the obtained precipitate with absolute ethyl alcohol until no dibutyltin dilaurate exists in an effluent liquid, then controlling the rotation speed at 10000r/min, centrifuging for 15min, controlling the temperature of the precipitate obtained by centrifuging again at 60 ℃, drying, and collecting a dried product;

④, placing the dried product obtained in the step ③ into a muffle furnace, heating to 475 ℃ at the speed of 2 ℃/min, and calcining for 2 hours to obtain a sensitive material used for formaldehyde detection;

the sensitivity for detecting formaldehyde obtained above was measured by an X-ray diffractometer model D8-ADVANCE manufactured by Bruker-AXS, Germany, and the X-ray diffraction pattern obtained is shown in FIG. 1, from which FIG. 1 it can be seen that the sensitive material for detecting formaldehyde is mainly tin oxide and the diffraction peak is mainly tetragonal tin oxide (JCPDS 41-1445), thereby indicating that the main component of the sensitive material for detecting formaldehyde is tin oxide;

measuring the obtained sensitive material for detecting formaldehyde by using a Labram HR Evolution spectrometer produced by HORIBA company of Japan, wherein the obtained Raman spectrogram is shown in figure 2, and a Raman peak proves that the sensitive material for detecting formaldehyde is reduced graphene oxide doped tin oxide as can be seen from figure 2;

the sensitive material used for formaldehyde detection obtained in the above example 1 is scanned by using a quanta feg450 field emission scanning electron microscope manufactured by FEI company, usa, and the obtained SEM image is shown in fig. 3, and it can be seen from fig. 3 that the obtained sensitive material, i.e., the reduced graphene oxide-doped tin oxide nanosheet, is a large-size nanosheet structure, and has a length of 15-20 μm, a width of 10-15 μm, and a thickness of 3-5 nm.

The obtained sensitive material for formaldehyde detection is scanned by a Tecnai G2F30 type transmission electron microscope of FEI company in USA, the obtained TEM image is shown in FIG. 4, and it can be seen from FIG. 4 that the obtained sensitive material for formaldehyde detection, namely, the reduced graphene oxide doped tin oxide nanosheet, has a mesoporous structure on the surface, the mesopores are uniformly distributed, the pore diameter of the mesopores is about 3nm, and the specific surface area is 69.8m²·g^-1。

Roasting the obtained sensitive material for detecting formaldehyde by using a Pyris 1TGA thermal analyzer manufactured by PerkinElme company in America, detecting the relationship between the mass change and the temperature of the sensitive material for detecting formaldehyde in the roasting process, and obtaining a mass-temperature relationship diagram of the sensitive material as shown in FIG. 5, wherein the content of the reduced graphene oxide is 1.6 wt% in percentage by weight;

in summary, the obtained sensitive material for detecting formaldehyde has the thickness of 3-5nm, the length of 15-20 μm, the width of 10-15 μm, the surface of mesoporous structure, the mesoporous aperture of 3-5nm and the specific surface area of 69.8m according to the determination²·g^-1The tin oxide in the tin oxide nanoplatelets is tetragonal tin oxide, wherein the content of reduced graphene oxide is 1.6 wt% in terms of weight percent.

The preparation process of the sensitive material used for detecting formaldehyde is used for preparing a gas sensitive element in a gas sensor used for detecting formaldehyde and specifically comprises the following steps:

(1) adding deionized water into the obtained sensitive material for formaldehyde detection, and uniformly mixing to obtain pasty slurry;

the dosage of the sensitive material and the deionized water used for formaldehyde detection is as follows: calculating the proportion of deionized water of 20mg to 1 mL;

(2) uniformly coating the pasty slurry obtained in the step (1) on the surface of a semiconductor element, controlling the coating thickness to be 1mm, then controlling the temperature to be 60 ℃, drying for 2h, and then performing heat treatment for 2h at 400 ℃ to obtain the semiconductor element with a dried coating;

the semiconductor element is an alumina ceramic tube;

then, welding, aging and packaging the obtained semiconductor element with the dry coating and a base material according to a conventional indirectly heated semiconductor gas sensor manufacturing process to finally obtain a gas sensor used in the formaldehyde gas sensor;

the base material is a plastic-metal electrode base.

Performing gas-sensitive performance test on a gas-sensitive element in the gas sensor for detecting the obtained formaldehyde according to a static gas distribution method, specifically referring to reference document [1], by using a CGS-8 gas-sensitive element test system, wherein test curves are respectively shown in FIGS. 5-8;

fig. 6 is a graph showing the optimum operating temperatures measured at the operating temperatures of 40 to 90 c, and it can be seen from fig. 6 that the optimum temperature of the gas sensor for formaldehyde detection obtained corresponding to the calcination temperature of 475 c was 60 c, thereby indicating that the gas sensor for formaldehyde detection had a lower operating temperature. The highest value of the gas-sensitive property of the gas-sensitive material to formaldehyde in 100ppm formaldehyde aqueous solution reaches about 2200;

fig. 7 is a graph showing the selectivity of the gas sensor for detecting formaldehyde to gases such as formaldehyde, ethanol, acetone, methanol, ammonia gas, toluene and the like, measured at a working temperature of 60 ℃ and a gas concentration of 100ppm, and it can be seen from fig. 7 that the gas sensor for detecting formaldehyde of the present invention has an ultrahigh sensitivity to formaldehyde, and has a sensitivity to other gases such as ethanol, acetone, methanol, ammonia gas, toluene and the like which is far lower than that to formaldehyde, and even has no response, thereby showing that the gas sensor for detecting formaldehyde of the present invention has a good selectivity to formaldehyde;

FIG. 8 is a graph showing recovery curves of formaldehyde gas responses measured under conditions where the operating temperature is 60 ℃ and the concentrations of formaldehyde gas are 10ppm, 30ppm, 50ppm, and 100ppm, respectively, and it can be seen from FIG. 7 that the sensitivity of the gas sensor for formaldehyde detection to formaldehyde increases with the increase in the concentration of formaldehyde;

fig. 9 is a simulation graph showing the linear relationship between the sensitivity of the gas sensor for formaldehyde detection and the sensitivity of the gas sensor for formaldehyde detection measured at an operating temperature of 60 ℃ and formaldehyde gas concentrations of 10ppm, 30ppm, 50ppm, and 100ppm, and it can be seen from fig. 9 that the increase in formaldehyde concentration and the increase in sensitivity of the gas sensor for formaldehyde detection are linear, indicating that the sensitivity of the gas sensor for formaldehyde detection of the present invention has a positive linear relationship with formaldehyde gas concentration.

In summary, the gas sensor used for detecting formaldehyde of the present invention has the characteristics of low operating temperature, high sensitivity, and the like, and the sensitivity of the gas sensor used for detecting formaldehyde of the present invention under the same conditions is about 10 times higher than that of a commercially available instrument.

The sensitivity of the gas sensor used in the formaldehyde gas sensor obtained in example 1 to formaldehyde gas, the selectivity to various gases such as formaldehyde, ethanol, methanol, acetone, ammonia, toluene, and the like, the detection limit, and the like were measured by using a CGS-8 gas sensor test system according to a static gas distribution method with reference to reference [1], and the test conditions were as follows:

1. detection range: the gas concentration is 0.25ppm-100 ppm;

2. the working temperature of the element is as follows: 40-90 ℃;

the test results were as follows:

1. detection sensitivity (Ra/Rg): a formaldehyde sensitivity of about 2200 at 100 ppm;

2. and (3) selectivity: the sensitivity to 100ppm ethanol, methanol, acetone, ammonia gas and toluene is lower than the sensitivity to formaldehyde;

3. element response time: less than 70 s;

4. element recovery time: less than 90 s.

From the above test results, it can be seen that the sensitivity of the gas sensitive element in the gas sensor for detecting formaldehyde of the present invention to 100ppm formaldehyde reaches 2200, the response time is less than 70s, and the recovery time is less than 90s, thereby indicating that the gas sensitive element in the gas sensor for detecting formaldehyde of the present invention has high sensitivity to formaldehyde and fast response recovery speed, and these characteristics make it convenient for integration in the fields of household appliances, mobile electronic equipment, automobiles, etc., and make intelligent monitoring of formaldehyde ubiquitous.

Example 2

The sensitive material for detecting formaldehyde is prepared by the following steps:

the preparation process is different only in step ④, the dried product obtained in step ③ is put into a muffle furnace, and the temperature is raised to 500 ℃ at the speed of 2 ℃/min for calcination treatment for 2h, and the other steps are the same as those in example 1.

The obtained sensitive material used for detecting the formaldehyde is reduced graphene oxide doped tin oxide gas sensitive material with a mesoporous structure on the surface, and is a tin oxide nanosheet, the thickness is 10-15nm, the length is 5-10 mu m, the width is 5-8 mu m, the surface has the mesoporous structure, the mesoporous aperture is 5-10nm, and the specific surface area can reach 72.9m²·g^-1The tin oxide in the tin oxide nanosheet is a tetragonal tin oxide structure, wherein the content of the reduced graphene oxide is 0.5 wt% in terms of weight percentage.

The above-obtained sensitive material for formaldehyde detection was used for the preparation of the gas sensor in the gas sensor for formaldehyde detection, and the gas sensor in the gas sensor for formaldehyde detection was finally obtained in the same manner as in example 1.

Example 3

The sensitive material for detecting formaldehyde is prepared by the following steps:

the preparation process is different only in step ④, the dried product obtained in step ③ is put into a muffle furnace, and the temperature is raised to 450 ℃ at the speed of 1 ℃/min for calcination treatment for 2h, and the other steps are the same as those in example 1.

The obtained sensitive material used for formaldehyde detection is a reduced graphene oxide loaded tin oxide nanosheet with a mesoporous structure on the surface, the thickness is 5-10nm, the length is 10-12 mu m, the width is 5-10 mu m, the surface has a mesoporous structure, the mesoporous aperture is 5-10nm, and the specific surface area can reach 105.7m²·g^-1The tin oxide in the tin oxide nanosheet is a tetragonal tin oxide structure in which the content of reduced graphene oxide is 3.7 wt% in terms of weight percent.

The above-obtained sensitive material for formaldehyde detection was used for the preparation of the gas sensor in the gas sensor for formaldehyde detection, and the gas sensor in the gas sensor for formaldehyde detection was finally obtained in the same manner as in example 1.

In the case that the calcination temperatures of the gas sensors for formaldehyde detection prepared from the sensitive materials for formaldehyde detection (except the calcination temperatures of the gas sensors are different and the same) are respectively 450 ℃, 475 ℃ and 500 ℃ in the corresponding embodiments 1 to 3, the relationship curve diagram between the sensitivity to formaldehyde and the formaldehyde concentration of the gas sensors for formaldehyde detection prepared from the sensitive materials for formaldehyde detection (except the calcination temperatures of the gas sensors for formaldehyde detection) at the formaldehyde concentrations of 10ppm, 30ppm, 50ppm and 100ppm is shown in fig. 10, and it can be seen from fig. 10 that the gas sensors for formaldehyde detection prepared from the sensitive materials for formaldehyde detection corresponding to different calcination temperatures have good linear relationship to formaldehyde with different concentrations, so that the gas sensors are more convenient for data acquisition and processing when being actually applied to formaldehyde gas sensors. And the gas sensor for detecting formaldehyde, which is made of the sensitive material for detecting formaldehyde and obtained at the calcination temperature of 475 ℃, has the best response signal to formaldehyde.

In summary, the sensitive material used for formaldehyde detection in the invention is a reduced graphene oxide loaded tin oxide nanosheet with a mesoporous structure on the surface, the surface has the mesoporous structure, the mesoporous aperture is 3-10nm, the tin oxide in the tin oxide nanosheet is a tetragonal crystal system tin oxide structure, wherein the content of the reduced graphene oxide is 0.5-3.7 wt% in percentage by weight, and the surface has the mesoporous structure, so the tin oxide nanosheet has a large specific surface area, and the specific surface area can reach 69.8m²·g^-1-105.7m²·g^-1The surface of the gas sensor has more active sites, so that the gas sensor in the gas sensor for detecting formaldehyde prepared by the gas sensor has the advantages of high sensitivity, good selectivity to interference gas, strong response/recovery capability, low detection limit, stable performance and the like. The CGS-8 gas sensor test system is used for testing, the gas concentration is 0.25ppm-100ppm, the working temperature can be 40-90 ℃, the sensitivity of the CGS-8 gas sensor to 100ppm formaldehyde reaches 2200, the response time is less than 70s, and the recovery time is less than 90s, so that when the CGS-8 gas sensor is applied to a gas sensor for formaldehyde detection, the sensitivity and the selectivity of the formaldehyde gas sensor can be effectively improved, and the technical problems of low detection sensitivity and selectivity and the like in the prior art are solved.

Although the present invention has been described with reference to preferred embodiments, it is to be understood that the present invention is not limited to the disclosed embodiments, but rather, may be embodied in many different forms and modifications without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims (10)

Translated fromChinese

1.一种甲醛检测所用的敏感材料，其特征在于所述甲醛检测所用的敏感材料为表面具有介孔结构的负载还原氧化石墨烯的氧化锡纳米片；其中，氧化锡纳米片表面具有均匀的介孔结构且还原氧化石墨烯掺杂于氧化锡纳米片上。1. a used sensitive material for formaldehyde detection is characterized in that the used sensitive material for described formaldehyde detection is the tin oxide nanosheet of the loaded reduced graphene oxide with mesoporous structure on the surface; wherein, the tin oxide nanosheet surface has a uniform surface. Mesoporous structure and reduced graphene oxide doped on tin oxide nanosheets.2.如权利要求1所述的甲醛检测所用的敏感材料，其特征在于所述的表面具有介孔结构的负载还原氧化石墨烯的氧化锡纳米片，其厚度为3～15nm，长为5～20μm、宽为5～15μm，比表面积达69.8m·g-105.7m·g，表面介孔分布均匀，孔径为3-10nm。2. the used sensitive material of formaldehyde detection as claimed in claim 1, is characterized in that described surface has the tin oxide nano-sheet of the loaded reduced graphene oxide of mesoporous structure, and its thickness is 3～15nm, length is 5～ 20μm, the width is 5-15μm, the specific surface area is 69.8m·g-105.7m·g, the surface mesopores are evenly distributed, and the pore size is 3-10nm.3.如权利要求1所述的甲醛检测所用的敏感材料，其特征在于所述的表面具有介孔结构的负载还原氧化石墨烯的氧化锡纳米片，其中的还原氧化石墨烯的含量为0.5-50wt％，氧化锡为四方晶系结构。3. the used sensitive material of formaldehyde detection as claimed in claim 1 is characterized in that described surface has the tin oxide nano-sheet of the loaded reduced graphene oxide of mesoporous structure, wherein the content of reduced graphene oxide is 0.5- 50wt%, tin oxide has a tetragonal structure.4.如权利要求3所述的甲醛检测所用的敏感材料，其特征在于所述的表面具有介孔结构的负载还原氧化石墨烯的氧化锡纳米片，其中的还原氧化石墨烯的含量为0.5-3.7wt％，氧化锡为四方晶系结构。4. the used sensitive material of formaldehyde detection as claimed in claim 3 is characterized in that described surface has the tin oxide nano-sheet of the loaded reduced graphene oxide of mesoporous structure, wherein the content of reduced graphene oxide is 0.5- 3.7wt%, tin oxide has a tetragonal structure.5.如权利要求1所述的甲醛检测所用的敏感材料的制备方法，其特征在于具体包括如下步骤：①、将氧化石墨烯加入无水乙醇中，控制功率为400W，频率为32KHz进行超声处理30min，以使氧化石墨烯均匀分散在无水乙醇中，得到氧化石墨烯分散液；上述氧化石墨烯和无水乙醇的用量，按氧化石墨烯：无水乙醇为10-200mg：20-200mL的比例计算；②、将锡源加入到步骤①所得的氧化石墨烯分散液中，控制温度为10～50℃、转速为1000r/min进行搅拌12-18h，得到混合溶液；所述的锡源为四氯化锡、二月桂酸二丁基锡或锡酸四正丁酯；锡源的加入量，按体积比计算，氧化石墨烯分散液：锡源为1：4-16；③、将步骤②所得的混合溶液控制转速10000r/min进行离心15min，所得的沉淀用无水乙醇进行洗涤至流出液中没有锡源为准，然后再次控制转速10000r/min进行离心15min，将再次离心所得的沉淀控制温度为60℃进行干燥，收集干燥后的产物；④、将步骤③所得干燥后的产物放入马弗炉中，以1-5℃/min的速率升温至450～500℃进行煅烧处理2-12h，即得甲醛检测所用的敏感材料；所述敏感材料中包括氧化锡纳米片且氧化锡纳米片表面具有均匀的介孔结构、还原氧化石墨烯掺杂于氧化锡纳米片上。5. the preparation method of the used sensitive material of formaldehyde detection as claimed in claim 1, is characterized in that specifically comprising the steps: 1., graphene oxide is added in dehydrated alcohol, control power is 400W, and frequency is that 32KHz carries out ultrasonic treatment 30min, so that graphene oxide is evenly dispersed in dehydrated alcohol, obtains graphene oxide dispersion liquid; The consumption of above-mentioned graphene oxide and dehydrated alcohol, according to graphene oxide: dehydrated alcohol is 10-200mg: 20-200mL Proportion calculation; 2. adding the tin source into the graphene oxide dispersion liquid obtained in step 1., the control temperature is 10～50 ℃, the rotating speed is 1000r/min, and stirring is performed for 12-18h to obtain a mixed solution; the tin source is Tin tetrachloride, dibutyltin dilaurate or tetra-n-butyl stannate; the added amount of the tin source is calculated by volume ratio, and the graphene oxide dispersion liquid: the tin source is 1:4-16; The mixed solution was centrifuged at 10000r/min for 15min, the obtained precipitate was washed with absolute ethanol until there was no tin source in the effluent, and then the rotating speed was controlled at 10000r/min for 15min, and the temperature of the precipitate obtained by centrifugation was controlled again. Dry at 60°C, and collect the dried product; 4. Put the dried product obtained in step 3 into a muffle furnace, and heat it up to 450-500°C at a rate of 1-5°C/min for calcination for 2-12h , the sensitive material used for formaldehyde detection is obtained; the sensitive material includes tin oxide nanosheets and the surface of the tin oxide nanosheets has a uniform mesoporous structure, and reduced graphene oxide is doped on the tin oxide nanosheets.6.如权利要求5所述的甲醛检测所用的敏感材料的制备方法，其特征在于具体包括如下：步骤①中：氧化石墨烯和无水乙醇的用量，按氧化石墨烯：无水乙醇为100mg:200mL的比例计算；步骤②中：控制温度为25℃、转速为1000r/min进行搅拌16h，得到混合溶液；所述的锡源为二月桂酸二丁基锡，按体积比计算，氧化石墨烯分散液：锡源为1：16；步骤④中：将步骤③所得干燥后的产物放入马弗炉中，以2℃/min的速率升温至475℃进行煅烧处理2h。6. the preparation method of the used sensitive material of formaldehyde detection as claimed in claim 5 is characterized in that specifically comprising the following: step 1. in: the consumption of graphene oxide and dehydrated alcohol, by graphene oxide: dehydrated alcohol is 100mg In step 2.: control temperature is 25 DEG C, rotating speed is 1000r/min and stirs 16h, obtains mixed solution; Described tin source is dibutyltin dilaurate, calculated by volume ratio, graphene oxide is dispersed Liquid: tin source is 1:16; in step 4: put the dried product obtained in step 3 into a muffle furnace, and heat up to 475°C at a rate of 2°C/min for calcination for 2h.7.如权利要求1所述的甲醛检测所用的敏感材料用于甲醛检测所用的气体传感器中的气敏元件的制备，其制备过程具体包括如下步骤：(1)、在甲醛检测所用的敏感材料中加入去离子水或无水乙醇，混合均匀后得到糊状浆料；甲醛检测所用的敏感材料和去离子水或无水乙醇的用量，按甲醛检测所用的敏感材料：去离子水或无水乙醇为20mg:1ml的比例计算；上述的甲醛检测所用的敏感材料通过包括如下步骤的方法制备而成：①、将氧化石墨烯加入无水乙醇中，控制功率为400W，频率为32KHz 进行超声处理30min，以使氧化石墨烯均匀分散在无水乙醇中，得到氧化石墨烯分散液；上述氧化石墨烯和无水乙醇的用量，按氧化石墨烯：无水乙醇为10-200mg：20-200mL的比例计算；②、将锡源加入到步骤①所得的氧化石墨烯分散液中，控制温度为10～50℃、转速为1000r/min进行搅拌12-18h，得到混合溶液；所述的锡源为四氯化锡、二月桂酸二丁基锡或锡酸四正丁酯；锡源的加入量，按体积比计算，氧化石墨烯分散液：锡源为1：4-16；③、将步骤②所得的混合溶液控制转速10000r/min进行离心15min，所得的沉淀用无水乙醇进行洗涤至流出液中没有锡源为准，然后再次控制转速10000r/min进行离心15min，将再次离心所得的沉淀控制温度为60℃进行干燥，收集干燥后的产物；④、将步骤③所得干燥后的产物放入马弗炉中，以1-5℃/min的速率升温至450～550℃进行煅烧处理2-12h，即得甲醛检测所用的敏感材料；所述敏感材料中包括氧化锡纳米片且氧化锡纳米片表面具有均匀的介孔结构、还原氧化石墨烯掺杂于氧化锡纳米片上；(2)将步骤(1)所得的糊状浆料均匀涂覆在半导体元件的表面，控制涂覆厚度为0.5-1.5mm，然后控制温度为60℃进行干燥，然后再控制温度为400℃进行热处理2h，得到具有干燥涂层的半导体元件；所述的半导体元件为氧化铝陶瓷管；然后，按常规的旁热式半导体气敏元件制作工艺将上述所得的具有干燥涂层的半导体元件与基座材料进行焊接、老化和封装，最终得到甲醛检测所用的气体传感器中的气敏元件；所述的基座材料是塑料-金属电极基座。7. the used sensitive material of formaldehyde detection as claimed in claim 1 is used for the preparation of the gas sensor in the used gas sensor of formaldehyde detection, and its preparation process specifically comprises the steps: (1), in the used sensitive material of formaldehyde detection Add deionized water or anhydrous ethanol, and mix evenly to obtain a paste slurry; the sensitive material used for formaldehyde detection and the amount of deionized water or anhydrous ethanol, according to the sensitive material used in formaldehyde detection: deionized water or anhydrous Ethanol is calculated at the ratio of 20mg:1ml; the sensitive material used in the above-mentioned formaldehyde detection is prepared by a method comprising the following steps: 1., adding graphene oxide to absolute ethanol, the control power is 400W, and the frequency is 32KHz to carry out ultrasonic treatment 30min, so that graphene oxide is evenly dispersed in dehydrated alcohol, obtains graphene oxide dispersion liquid; The consumption of above-mentioned graphene oxide and dehydrated alcohol, according to graphene oxide: dehydrated alcohol is 10-200mg: 20-200mL Proportion calculation; 2. adding the tin source into the graphene oxide dispersion liquid obtained in step 1., the control temperature is 10～50 ℃, the rotating speed is 1000r/min, and stirring is performed for 12-18h to obtain a mixed solution; the tin source is Tin tetrachloride, dibutyltin dilaurate or tetra-n-butyl stannate; the added amount of the tin source is calculated by volume ratio, and the graphene oxide dispersion liquid: the tin source is 1:4-16; The mixed solution was centrifuged at 10000r/min for 15min, the obtained precipitate was washed with absolute ethanol until there was no tin source in the effluent, and then the rotating speed was controlled at 10000r/min for 15min, and the temperature of the precipitate obtained by centrifugation was controlled again. Dry at 60°C, and collect the dried product; 4. Put the dried product obtained in step 3 into a muffle furnace, and heat it up to 450-550°C at a rate of 1-5°C/min for calcination for 2-12h , that is, the sensitive material used for formaldehyde detection is obtained; the sensitive material includes tin oxide nanosheets and the surface of the tin oxide nanosheets has a uniform mesoporous structure, and reduced graphene oxide is doped on the tin oxide nanosheets; (2) step (1) The obtained paste slurry is uniformly coated on the surface of the semiconductor element, and the coating thickness is controlled to be 0.5-1.5 mm, and then the temperature is controlled to be 60°C for drying, and then the temperature is controlled to be 400°C for heat treatment for 2 hours to obtain a The semiconductor element with the dry coating; the semiconductor element is an alumina ceramic tube; then, the semiconductor element with the dry coating obtained above is welded with the base material according to the conventional manufacturing process of the bypass-heated semiconductor gas sensor element, After aging and packaging, the gas sensor in the gas sensor used for formaldehyde detection is finally obtained; the base material is a plastic-metal electrode base.8.如权利要求7所述的甲醛检测所用的敏感材料用于甲醛检测所用的气体传感器中的气敏元件的制备，其特征在于其制备过程中：步骤(1)中的①：氧化石墨烯和无水乙醇的用量，按氧化石墨烯：无水乙醇为100mg：200mL的比例计算；②：控制温度为25℃转速为1000r/min进行搅拌16h；所述的锡源为二月桂酸二丁基锡；锡源的加入量，按体积比计算，氧化石墨烯分散液：锡源为1：16；③、控制温度为60℃进行干燥；④、以2℃/min的速率升温至475℃进行煅烧处理2h； 步骤(2)中：控制涂覆厚度为1mm。8. the used sensitive material of formaldehyde detection as claimed in claim 7 is used for the preparation of the gas sensor in the used gas sensor of formaldehyde detection, it is characterized in that in its preparation process: ① in step (1): graphene oxide and the consumption of anhydrous ethanol, according to the ratio of graphene oxide: anhydrous ethanol is 100mg: 200mL; ②: the control temperature is 25 ° C and the rotating speed is 1000r/min to stir for 16h; the tin source is dibutyltin dilaurate ; The addition of tin source, calculated by volume ratio, graphene oxide dispersion: tin source is 1:16; 3., the control temperature is 60 ℃ to dry; 4., be warming up to 475 ℃ with the speed of 2 ℃/min and carry out calcination Treat for 2h; In step (2): control the coating thickness to be 1mm.9.如权利要求7或8所述的甲醛检测所用的敏感材料用于甲醛检测所用的气体传感器中的气敏元件的制备得到的一种甲醛检测所用的气体传感器中的气敏元件，利用CGS-8气敏元件测试系统测试，气体浓度0.25ppm-100ppm，工作温度40-90℃的条件下，其对100ppm甲醛灵敏度约为2200、响应恢复时间均小于90s。9. the used sensitive material of formaldehyde detection as claimed in claim 7 or 8 is used for the gas sensor in the used gas sensor of a kind of formaldehyde detection that the preparation of the gas sensor in the used gas sensor of formaldehyde detection obtains, utilizes CGS -8 gas sensor test system test, the gas concentration is 0.25ppm-100ppm, and the working temperature is 40-90℃, the sensitivity to 100ppm formaldehyde is about 2200, and the response recovery time is less than 90s.10.如权利要求9所述的一种甲醛检测所用的气体传感器中的气敏元件，利用CGS-8气敏元件测试系统测试，工作温度60℃的条件下，其对100ppm甲醛灵敏度约为2200、响应时间小于70s、恢复时间小于90s。10. The gas sensor in the used gas sensor for formaldehyde detection as claimed in claim 9 is tested by CGS-8 gas sensor test system, and its sensitivity to 100ppm formaldehyde is about 2200 under the condition of operating temperature of 60°C. , The response time is less than 70s, and the recovery time is less than 90s.

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