CN110161091B - Gas sensing module and preparation method and application thereof - Google Patents

Gas sensing module and preparation method and application thereof Download PDF

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CN110161091B
CN110161091B CN201810956342.9A CN201810956342A CN110161091B CN 110161091 B CN110161091 B CN 110161091B CN 201810956342 A CN201810956342 A CN 201810956342A CN 110161091 B CN110161091 B CN 110161091B
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gas
noble metal
tin dioxide
layer
loaded
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CN110161091A (en
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赵宇鑫
胡适
牟善军
刘全桢
王林
张健中
梁文杰
霍子扬
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China Petroleum and Chemical Corp
Institute of Physics of CAS
Sinopec Safety Engineering Research Institute Co Ltd
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Sinopec Safety Engineering Research Institute Co Ltd
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Abstract

The invention relates to the field of novel functional materials, and discloses a gas sensing module and a preparation method and application thereof, wherein the gas sensing module comprises a micro-sensor chip and a noble metal loaded gas-sensitive sensing material loaded on the micro-sensor chip; the noble metal-loaded gas-sensitive sensing material comprises a tin dioxide carrier and a noble metal loaded on the tin dioxide carrier, wherein the noble metal is selected from one or more of metal elements in IB groups and VIII groups. The gas sensing module provided by the invention has the characteristics of simple and convenient material preparation method, high yield, simple noble metal loading mode, small using amount, good sensitivity and stability, lower resistance and the like.

Description

Gas sensing module and preparation method and application thereof
Technical Field
The invention relates to the field of novel functional materials, in particular to a gas sensing module and a preparation method and application thereof.
Background
Among the many gas-sensitive sensing materials known at present, tin dioxide is the most commonly used one with the best reproducibility and the most stable response, but is also the less specific one. Due to tin dioxide pairs such as H2、CO、H2S、NOxAnd various gases have response of different degrees, and are not suitable to be used as sensitive materials for single gas detection. In recent years, with the development of technologies such as smart detection, multi-component gas sensors have become indispensable technical tools in the field of analytical detection. Based on a large-scale gas sensor array, development and integration of an intelligent detection device with large data characteristics provide favorable strategy support for a new-generation multifunctional integrated sensing system. Noble metal (such as Ag, Au, Pd, Pt and the like) doping, modification, loading and modification differentiated based on the spectral response characteristics of tin dioxide provide a solution for simultaneously meeting the broad spectrum and the difference of gas-sensitive response. The development and application of the integrated comprehensive state recognition sensor have the advantages that revolutionary substitution functions are single, information is dispersed, and the modern sensor equipment for monitoring and early warning of complex atmosphere cannot be realized. The current commercial instrument can be comprehensively outperformed in the indexes such as detection sensitivity, response speed, complex environment assessment accuracy and the like through means of device integration, data processing and information extraction. However, the existing tin dioxide-based gas sensing module still has the problem of single type, and cannot meet the detection requirement.
Disclosure of Invention
The invention aims to solve the problems of low material yield, large noble metal particles obtained by a noble metal loading mode, and poor stability and sensitivity of materials in the prior art, and provides a gas sensing module, a preparation method and application thereof.
In order to achieve the above object, an aspect of the present invention provides a gas sensing module including a micro sensor chip and a noble metal-loaded gas sensitive sensing material loaded on the micro sensor chip; the noble metal-loaded gas-sensitive sensing material comprises a tin dioxide carrier and a noble metal loaded on the tin dioxide carrier, wherein the noble metal is selected from one or more of metal elements in IB groups and VIII groups.
Preferably, the noble metal is selected from one or more of Ag, Au, Pd and Pt.
Preferably, the tin dioxide carrier is a tin dioxide microsphere.
More preferably, the tin dioxide microspheres have a diameter of 0.5-2.5 μm.
More preferably, the tin dioxide microspheres have a flower-like structure.
More preferably, the supported amount of the noble metal is 0.005 to 0.03 parts by weight in terms of the noble metal element, relative to 1 part by weight of the tin dioxide carrier.
Preferably, the microsensor chip comprises a substrate and a sensing electrode arranged on the substrate.
More preferably, the microsensor chip further comprises a heating electrode.
Preferably, the microsensor chip comprises an electrode layer, an insulating layer, a heating layer, a supporting layer, a suspension layer and a substrate layer which are sequentially stacked, wherein through holes are formed in the suspension layer and the region, corresponding to the heating layer, on the substrate layer.
In a second aspect, the present invention provides a method for manufacturing a gas sensing module, the method including:
1) mixing a tin-containing compound, C2-C6 organic dibasic acid, hydrazine hydrate and hydrochloric acid, carrying out hydrothermal reaction, and then carrying out solid-liquid separation to obtain a tin dioxide carrier;
2) loading a noble metal on the tin dioxide carrier to obtain a noble metal loaded gas-sensitive sensing material;
3) loading the noble metal loaded gas-sensitive sensing material on a microsensor chip;
wherein the noble metal is selected from one or more of metal elements of IB group and VIII group.
Preferably, the noble metal is selected from one or more of Ag, Au, Pd and Pt.
Preferably, the tin-containing compound is selected from one or more of stannous dichloride, stannous tetrachloride, stannous oxide and stannous oxalate.
More preferably, the molar ratio of the tin-containing compound to the C2-C6 organic dibasic acid, the hydrazine hydrate and the hydrochloric acid is 1: 3-5.5: 3-25: 0.2-0.48.
More preferably, the organic dibasic acid of C2-C6 is selected from one or more of oxalic acid, malonic acid, succinic acid, glutaric acid and adipic acid.
More preferably, the organic dibasic acid of C2-C6 is oxalic acid.
Preferably, the conditions of the hydrothermal reaction include: the temperature is 160-200 ℃ and the time is 4-20 h.
Preferably, the noble metal is supported on the tin dioxide support by an impregnation method.
Preferably, the tin dioxide carrier is impregnated with a noble metal precursor, and is subjected to ultraviolet light irradiation, wherein the noble metal precursor is a water-soluble noble metal salt of one or more selected from metal elements of groups IB and VIII.
Preferably, the noble metal precursor is selected from AgNO3、AuCl3、Pd(OAc)2、K2PtCl4、PdCl2And Pd (acac)2One or more of (a).
Preferably, the noble metal precursor is used in an amount of preferably 0.005 to 0.03 parts by weight in terms of noble metal element, relative to 1 part by weight of the tin dioxide carrier.
Preferably, the conditions of the ultraviolet light irradiation include: the time is 10-60 min.
Preferably, the microsensor chip comprises a substrate and a sensing electrode arranged on the substrate.
More preferably, the microsensor chip further comprises a heating electrode.
Preferably, the microsensor chip comprises an electrode layer, an insulating layer, a heating layer, a supporting layer, a suspension layer and a substrate layer which are sequentially stacked, wherein through holes are formed in the suspension layer and the region, corresponding to the heating layer, on the substrate layer.
The invention also provides a gas sensing module array, which consists of more than two gas sensing modules or the gas sensing modules obtained by the preparation method, wherein the gas sensing modules are loaded with different noble metal loaded gas-sensitive sensing materials.
The invention also provides the application of the gas sensing module, the gas sensing module obtained by the preparation method, or the gas sensing module array in the field of leakage detection, dangerous gas detection or human body protection.
Through the technical scheme, the noble metal loaded tin dioxide flower-shaped structure has uniform assembly size, larger specific surface area and obvious gas-sensitive response. The tin dioxide structure loaded with noble metal has a structure higher than SnO2Response sensitivity of the bulk material; depending on different loaded metals, the material generates different gas-sensitive responses to gases such as carbon monoxide, hydrogen sulfide and the like; the method is expected to realize accurate sensing of mixed gas by constructing a multi-dimensional sensor array and combining an advanced simulation algorithm, can be widely applied to areas with relatively dense distribution of toxic, harmful, flammable and explosive gases such as petrochemical plants and the like, and can realize monitoring, component identification and alarm application of complex atmosphere states.
The preparation method provided by the invention is simple and convenient, low in energy consumption and easy for expanded production. The size of the noble metal loaded stannic oxide flower-like nanostructure can be regulated and controlled by regulating the temperature, the reaction time and the raw material ratio in the preparation process in a laboratory. In the actual production process, the scale-up production can be carried out according to specific conditions.
Drawings
FIG. 1 is a graph of Ag @ SnO obtained in example 12Au @ SnO obtained in example 42Pd @ SnO obtained in example 52Pt @ SnO obtained in example 62And the unsupported SnO obtained according to comparative example 12X-ray diffraction patterns of (a);
FIG. 2 is the Ag @ SnO obtained in example 12(a, b) and unsupported SnO obtained from comparative example 12Scanning electron micrographs of (c, d);
FIG. 3 is the Ag @ SnO obtained in example 12(a) And the unsupported SnO obtained in comparative example 12(b) Transmission electron microscope photograph of (1);
FIG. 4 is the Ag @ SnO obtained in example 12(left panel), Pd @ SnO obtained in example 52(right panel) for different concentrations of CO and H2S gas and the response curve of the mixed gas of the S gas and the mixed gas;
fig. 5 is a schematic structural view of the microsensor chip obtained in preparation example 1.
Description of the reference numerals
1. Sensing electrode 2, heating electrode
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
According to the gas sensing module, the gas sensing module comprises a micro sensor chip and a noble metal loaded gas-sensitive sensing material loaded on the micro sensor chip; the noble metal-loaded gas-sensitive sensing material comprises a tin dioxide carrier and a noble metal loaded on the tin dioxide carrier, wherein the noble metal is selected from one or more of metal elements in IB groups and VIII groups.
Preferably, the noble metal is selected from one or more of Ag, Au, Pd and Pt.
In the invention, the precious metal is loaded on the tin dioxide carrier, so that the gas-sensitive response speed and sensitivity of the tin dioxide can be obviously improved, and the relative response strength to different gas components can be reflected in a differentiated manner. The gas sensing module can simultaneously respond to different gases, more than two gas sensing modules of the invention selected from the group consisting of different gas-sensitive sensing materials and the same gas-sensitive material with different loading capacity are matched with each other to form a gas sensing module array, and the gas sensing module array based on the series of materials can be possible to analyze the components of the complex gas by utilizing a data analysis algorithm at the rear end; the comprehensive identification capability of the gas sensing module under the actual atmosphere environment is greatly improved, and the gas sensing module has extremely high sensitivity and detection speed. The gas to which the gas sensor material responds may be, for example, H2、CO、H2S、NOxToluene, butane and the like, and can be widely applied to the detection of toxic, harmful, flammable and explosive gases.
According to the present invention, the shape of the tin dioxide support is not particularly limited as long as the purpose of responding to different gases can be achieved, and the tin dioxide support is preferably tin dioxide microspheres, more preferably having a flower-like structure, and the diameter of the tin dioxide microspheres may be, for example, 0.5 to 2.5 μm, preferably 0.5 to 2 μm.
In order to further improve the gas sensitive response speed and sensitivity of the resulting material, as the supported amount of the noble metal, the supported amount of the noble metal is 0.005 to 0.03 parts by weight, preferably 0.007 to 0.02 parts by weight, and more preferably 0.01 to 0.002 parts by weight in terms of the noble metal element, relative to 1 part by weight of the tin dioxide carrier.
According to the present invention, the structure of the microsensor chip is not particularly limited as long as the gas sensitive sensing material can be supported by the noble metal and response to different gases can be achieved.
As a preferred microsensor chip of the present invention, for example, as shown in fig. 5, the microsensor chip may comprise a substrate and a sensing electrode 1 disposed on the substrate. The gas-sensitive sensing material is loaded on the sensing electrode, so that high-sensitivity detection of gas can be realized. Preferably, the microsensor chip further comprises a heating electrode 2, such as a resistance wire, the heating electrode 2 being used to provide a suitable operating temperature for the gas sensing module. The gas-sensitive sensing material is connected to an external circuit through a sensing electrode 1, a heating electrode 2 penetrates between the electrodes, and the temperature of the material can be regulated and controlled by changing the voltage applied to the heating electrode 2.
As another preferable microsensor chip of the present invention, the microsensor chip includes an electrode layer (including a sensing electrode), an insulating layer, a heating layer (including a heating electrode), a support layer, a suspended layer, and a substrate layer, which are stacked in this order, and through holes are provided in regions on the suspended layer and the substrate layer corresponding to the heating layer. By forming the suspension structure, heat dissipation can be reduced, power consumption is reduced, response sensitivity is improved, and response time is shortened.
The preparation method of the gas sensing module comprises the following steps:
1) mixing a tin-containing compound, C2-C6 organic dibasic acid, hydrazine hydrate and hydrochloric acid, carrying out hydrothermal reaction, and then carrying out solid-liquid separation to obtain a tin dioxide carrier;
2) loading a noble metal on the tin dioxide carrier to obtain a noble metal loaded gas-sensitive sensing material;
3) loading the noble metal loaded gas-sensitive sensing material on a microsensor chip;
wherein the noble metal is selected from one or more of metal elements in IB group and VIII group.
Preferably, the noble metal is selected from one or more of Ag, Au, Pd and Pt.
In the step 1), the tin-containing compound is a compound that can be dissolved in an acidic aqueous solution to obtain a tin cation (Sn)4+Or Sn2+) That is, an inorganic salt or oxide containing tin is preferable. The tin-containing compound may be selected from stannous dichloride, tetraOne or more of stannic chloride, stannous oxide and stannous oxalate, wherein stannous dichloride dihydrate is preferred.
In order to obtain a tin dioxide carrier with uniform size and good performance, the molar ratio of the tin-containing compound to the organic dibasic acid of C2-C6, the hydrazine hydrate, and the hydrochloric acid is preferably 1: 3-5.5: 3-25: 0.2-0.48, more preferably 1: 3.5-5.5: 3-20: 0.35-0.45.
In the step 1), the organic dibasic acid having 2 to 6 is not particularly limited, and may be one or more selected from oxalic acid, malonic acid, succinic acid, glutaric acid and adipic acid, and oxalic acid is preferred. The hydrochloric acid used is preferably concentrated hydrochloric acid, more preferably 35% (mass concentration, the same applies hereinafter).
In order to obtain a tin dioxide carrier with uniform size and good performance, the water-soluble tin salt, the organic dibasic acid of C2-C6, hydrazine hydrate and hydrochloric acid are mixed, stirred uniformly to obtain a homogeneous system, and then hydrothermal treatment is carried out. The conditions for the hydrothermal reaction include: the temperature is 160-200 ℃ and the time is 4-30h, preferably, the temperature is 170-180 ℃ and the time is 16-24 h. By carrying out the hydrothermal reaction under the conditions, the stannic oxide with a flower-like structure with uniform assembly size can be obtained, has larger specific surface area, obvious gas-sensitive response and is convenient for loading noble metals.
In order to remove impurities adsorbed on the tin dioxide carrier, the tin dioxide carrier is preferably further washed with deionized water after solid-liquid separation, specifically, deionized water may be added for ultrasonic dispersion, and then centrifugal collection is performed again, and the process is repeated for more than 2 times.
According to the invention, the noble metal is preferably supported on the tin dioxide support by means of an impregnation method. Specifically, the tin dioxide carrier may be impregnated with a noble metal precursor, which is a water-soluble noble metal salt of one or more kinds of metal elements selected from group IB and group VIII, and subjected to ultraviolet irradiation. The noble metal precursor preferably used includes, for example, a precursor selected from AgNO3、AuCl3、Pd(OAc)2、K2PtCl4、PdCl2And Pd (acac)2(palladium bisacetylacetonate).
In order to achieve a suitable loading amount, the noble metal precursor is used in an amount of preferably 0.005 to 0.03 parts by weight, preferably 0.007 to 0.02 parts by weight, and more preferably 0.01 to 0.002 parts by weight, in terms of noble metal element, relative to 1 part by weight of the tin dioxide carrier. The concentration of the noble metal precursor in the impregnation process may be, for example, 0.1 to 2mg/mL, preferably 0.15 to 0.5 mg/mL. The impregnation process can adopt the existing methods for impregnating the carrier, such as saturated impregnation, equal-volume impregnation and the like, as long as the combination of the noble metal precursor and the tin dioxide carrier can be completed.
After the dipping, the obtained gas sensor material is preferably washed and dried, and as a washing mode, for example, deionized water can be added for washing, then centrifugal separation is performed again, and the washing is repeated for more than two times; as a drying method, can be in 65-75 degrees C (for example, 70 degrees C) oven. Soluble impurities in the gas sensor material can be removed through washing and drying, and the purposes of reducing the interference of the impurities and improving the stability and sensitivity of the material are achieved.
In order to obtain the noble metal simple substance (such as Ag, Pd) or the noble metal oxide from the noble metal precursor, it is preferable to decompose the noble metal precursor under the irradiation of ultraviolet light, thereby obtaining the noble metal simple substance. The conditions of the ultraviolet irradiation include: the time is 10-60min, the power is 150-500W, and preferably, the ultraviolet irradiation conditions comprise: the time is 10-40min, the power is 250-350W, for example, the conditions of the ultraviolet irradiation can include: the time is 10-40min, and the power is 280-300W.
According to the present invention, the structure of the microsensor chip is not particularly limited as long as it can support the noble metal-supported gas-sensitive sensing material and realize the response to different gases, and for example, includes H2、CO、H2S、NOxToluene, butane, etc.
As a preferred microsensor chip of the present invention, for example, as shown in fig. 5, the microsensor chip may comprise a substrate and a sensing electrode 1 disposed on the substrate. The gas-sensitive sensing material is loaded on the sensing electrode, so that high-sensitivity detection of gas can be realized. Preferably, the microsensor chip further comprises a heating electrode 2, such as a resistance wire, the heating electrode 2 being used to provide a suitable operating temperature for the gas sensing module. The gas-sensitive sensing material is connected to an external circuit through a sensing electrode 1, a heating electrode 2 penetrates between the electrodes, and the temperature of the material can be regulated and controlled by changing the voltage applied to the heating electrode 2. The micro sensor chip can be prepared by a method which can be used for preparing the micro sensor chip, for example, a micromachining method such as photoetching, evaporation and the like can be used for preparing the substrate.
As another preferable microsensor chip of the present invention, the microsensor chip includes an electrode layer, an insulating layer, a heating layer, a support layer, a suspended layer, and a substrate layer, which are sequentially stacked, and through holes are provided in regions on the suspended layer and the substrate layer corresponding to the heating layer. By forming the suspension structure, heat dissipation can be reduced, power consumption is reduced, response sensitivity is improved, and response time is shortened. As a preparation method of the microsensor chip, a metal heating wire and a heating electrode connected with the heating wire can be prepared on a silicon wafer (such as a P-type (100) monocrystalline silicon wafer with silicon oxide double-sided polished) with a silicon oxide layer as a supporting layer, a suspended layer and a substrate layer by photoetching and vacuum evaporation; growing SiO by vapor deposition (such as PECVD)2As an insulating layer; then, preparing an interdigital electrode (a sensing electrode) as an electrode layer by using photoetching and thermal evaporation methods; then, the suspended layer and the substrate layer corresponding to the electrode region are removed, specifically by chemical etching, such as BOE solution (HF and NH)4F ratio is 1:7), etching the insulating layer, and etching the suspended layer by using a tetramethyl ammonium hydroxide solution (5 wt% aqueous solution of tetramethyl ammonium hydroxide), thereby forming the micro-sensing chip with a suspended structure.
In the present invention, a method for loading the gas sensor material on the micro sensor chip is not particularly limited, and for example, the gas sensor material may be dissolved in a suitable solvent, loaded on the micro sensor chip by dropping, spraying or the like, and dried. Before use, the chip loaded with the gas-sensitive sensing material is preferably subjected to heat treatment, for example, heating at 300-500 ℃ for 1-5h, preferably at 400-500 ℃ for 1.5-3h, and for example, heating at 440 ℃ for 2 h.
In the use process of the gas sensing module of the present invention, the micro sensor chip is preferably powered by an external circuit, so that the gas sensing material is detected at a required working temperature, which is, for example, 200-300 ℃. For more accurate measurement, it is preferable that the gas sensor module of the present invention is subjected to an aging treatment before the start of measurement. The aging conditions may include, for example, 250-500 ℃ for 1-24 hours, preferably 280-320 ℃ for 1-6 hours.
According to the gas sensing module array, the gas sensing module array is composed of more than two gas sensing modules or the gas sensing modules obtained by the preparation method, and the gas sensing modules are loaded with different noble metal loaded gas-sensitive sensing materials. The different gas-sensitive sensing materials loaded with the noble metal mean that the gas-sensitive sensing materials are different in the type and/or content of the loaded noble metal. The gas sensing module array formed by using different gas sensing materials loaded by the noble metal can finish the detection of different gas components in one detection process, greatly improves the detection efficiency, and has high accuracy and reliability because the final result is calculated by the detection results of different gas sensing modules.
The invention also provides the application of the gas sensing module, the gas sensing module obtained by the preparation method or the gas sensing module array in the field of leakage detection, dangerous gas detection or human body protection.
The present invention will be described in detail below by way of examples. In the following examples, X-ray diffraction was obtained from Paronaceae, the Netherlands under the model number X' Pert Pro; scanning Electron Microscope (SEM) purchased from Hitachi corporation under model number S4800; transmission electron microscopes are available from japan electronics as JEOL 2100.
Preparation example 1
The micro-processing method of photoetching and evaporation is adopted to prepare finger-like cross Au electrodes (with the width of 10 microns) as sensing electrodes 1 and Au resistance wires (with the width of 5 microns) for heating as heating electrodes 2 on the surface of a silicon wafer, so that the micro-sensor chip is obtained. And 3 of the microsensor chips are integrally connected to a control circuit board.
Example 1
(1) Mixing 1g of stannous dichloride dihydrate, 2g of oxalic acid and 100mL of deionized water, adding 0.1mL of concentrated hydrochloric acid (35%) and 2.16g of hydrazine hydrate (50 wt%), and stirring to form a transparent homogeneous mixed solution;
(2) putting the mixed solution into a reaction kettle, carrying out hydrothermal treatment at 160 ℃ for 20 hours, cooling, and carrying out centrifugal separation;
(3) collecting solid precipitate, adding deionized water, ultrasonically dispersing for 10min, centrifuging again, collecting, and repeating for 3 times to obtain stannic oxide microspheres;
(4) 0.1g of the tin dioxide microspheres are weighed and added with 10mL of AgNO with the concentration of 1mmol/L3Irradiating in water solution with xenon lamp ultraviolet light of power 300W for 20min to make AgNO3Decomposing, centrifuging at 10000 rpm/min for 5min, separating the residue, washing with deionized water, centrifuging again to separate the residue, and repeating for 2 times;
(5) collecting the final solid, and drying in an oven at 80 ℃ to obtain the Ag-loaded tin dioxide microsphere gas-sensitive sensing material (namely Ag @ SnO)2);
(6) Mixing the gas-sensitive sensing material and terpineol in a ratio of 1: 1.72 to form a slurry, dropping 20 microliters of the slurry onto 10 micron-spaced interdigitated electrodes, and drying in a 120 ℃ oven; the electrode is packaged in a polytetrafluoroethylene closed cavity and is connected with an external control system through a connecting circuit;
(7) and controlling the working temperature of the gas-sensitive sensing material within the range of 300 +/-5 ℃ by adjusting the load voltage on the resistance wire, and stably aging for 2h to obtain the gas sensing module 1.
As shown in FIG. 1, the Ag @ SnO was compared2With unsupported SnO2X-ray diffraction spectra and standards ofBy texture card, Ag @ SnO2Diffraction peaks of the sample near 44 ° and 79 ° are from the supported Ag particles.
Control unsupported SnO as shown in FIG. 22The scanning electron microscope photo shows that Ag @ SnO2The assembled structure of the sample was not significantly changed, the characteristics of the 3 micron-sized spherical assembled structure were maintained, and a large number of plate-shaped constituent structural units were visible on the surface.
Control unsupported SnO as shown in FIG. 32The transmission electron micrograph of Ag @ SnO2The final structure of the sample is changed, and the visible surface particles are enriched below 5 nm.
Example 2
(1) Mixing 1.6g of stannous dichloride dihydrate, 2g of oxalic acid and 100mL of deionized water, adding 0.1mL of concentrated hydrochloric acid (35%) and 2.4g of hydrazine hydrate (50 wt%), and stirring to form a transparent homogeneous system;
(2) putting the mixed solution into a reaction kettle, carrying out hydrothermal treatment at 180 ℃ for 12 hours, cooling, and carrying out centrifugal separation;
(3) collecting solid precipitate, adding deionized water, ultrasonically dispersing for 10min, centrifuging again, and collecting, repeating the process for 3 times to obtain stannic oxide microspheres;
(4) 0.1g of the tin dioxide microspheres are weighed and added with 10mL of AgNO with the concentration of 1.3mmol/L3Irradiating with xenon ultraviolet light in water solution for 20min to make AgNO3Decomposing, centrifuging at 10000 rpm/min for 5min, separating the residue, washing with deionized water, centrifuging again to separate the residue, and repeating for 2 times;
(5) collecting the final solid, and drying in an oven at 80 ℃ to obtain the Ag-loaded tin dioxide microsphere gas-sensitive sensing material (namely Ag @ SnO)2)。
The XRD pattern of the gas sensing material is similar to that of example 1, and relatively no SnO is loaded2Diffraction peaks near 44 ° and 79 ° are from the supported Ag particles. The SEM image and TEM image results of the product are similar to those of example 1, and the product is a three-dimensional spherical assembled structure with micron-sized structure units of particles with the sizes of 2-15 nm.
(6) A gas sensor module 2 was obtained in the same manner as in steps (6) to (7) in example 1.
Example 3
(1) Mixing 1.3g of stannous dichloride dihydrate, 2g of oxalic acid and 100mL of deionized water, adding 0.1mL of concentrated hydrochloric acid (35%) and 3.25g of hydrazine hydrate (50%), and stirring to form a transparent homogeneous system;
(2) putting the mixed solution into a reaction kettle, carrying out hydrothermal treatment at 200 ℃ for 4 hours, cooling, and carrying out centrifugal separation;
(3) collecting solid precipitate, adding deionized water, ultrasonically dispersing for 10min, centrifuging again, and collecting, repeating the process for 3 times to obtain stannic oxide microspheres;
(4) 0.1g of the tin dioxide microspheres are weighed and added with 10mL of AgNO with the concentration of 0.9mmol/L3Irradiating with xenon ultraviolet light in water solution for 20min to make AgNO3Decomposing, centrifuging at 10000 rpm/min for 5min, separating the residue, washing with deionized water, centrifuging again to separate the residue, and repeating for 2 times;
(5) collecting the final solid, and drying in an oven at 80 ℃ to obtain the Ag-loaded tin dioxide microsphere gas-sensitive sensing material (namely Ag @ SnO)2)。
The XRD pattern of the gas sensing material was similar to that of example 1, and diffraction peaks near 44 ° and 79 ° were derived from the supported Ag particles. The results of SEM and TEM images of the gas sensing material were similar to those of example 1, and were a three-dimensional spherical assembled structure of micron-sized dimensions, and the structural unit was a particle of several tens of nanometers in size.
(6) The gas sensor module 3 was obtained by following the methods of steps (6) to (7) in example 1.
Example 4
(1) 1g of stannous chloride dihydrate, 2g of oxalic acid and 100mL of deionized water are mixed, 0.1mL of concentrated hydrochloric acid (35%) and 2.16g of hydrazine hydrate (50 wt%) are added, and a transparent homogeneous system is formed by stirring;
(2) putting the mixed solution into a reaction kettle, carrying out hydrothermal treatment at 160 ℃ for 20 hours, cooling, and carrying out centrifugal separation;
(3) collecting solid precipitate, adding deionized water, ultrasonically dispersing for 10min, centrifuging again, and collecting, repeating the process for 3 times to obtain stannic oxide microspheres;
(4) weighing 0.1g of the tin dioxide microspheres, and mixing10mL of 1mmol/L AuCl was added3In the water solution, irradiating with xenon ultraviolet light for 20min to obtain AuCl3Decomposing, centrifuging at 10000 rpm/min for 5min, separating the residue, washing with deionized water, centrifuging again to separate the residue, and repeating for 2 times;
(5) collecting the final solid, and drying in an oven at 80 ℃ to obtain the Au-loaded tin dioxide microsphere gas-sensitive sensing material (namely Au @ SnO)2)。
The XRD pattern of the gas sensing material was similar to that of example 1, and diffraction peaks near 44 ° and 79 ° were derived from the supported Au particles. The results of SEM and TEM images of the gas sensing material were similar to those of example 1, and were a three-dimensional spherical assembled structure of micron-sized dimensions, and the structural unit was a particle of several tens of nanometers in size.
(6) The gas sensor module 4 was obtained by following the methods of steps (6) to (7) in example 1.
Example 5
(1) 1g of stannous chloride dihydrate, 2g of oxalic acid and 100mL of deionized water are mixed, 0.1mL of concentrated hydrochloric acid (35%) and 2.16g of hydrazine hydrate (50 wt%) are added, and a transparent homogeneous system is formed by stirring;
(2) putting the mixed solution into a reaction kettle, carrying out hydrothermal treatment at 160 ℃ for 20 hours, cooling, and carrying out centrifugal separation;
(3) collecting solid precipitate, adding deionized water, ultrasonically dispersing for 10min, centrifuging again, and collecting, repeating the process for 3 times to obtain stannic oxide microspheres;
(4) 0.1g of the above tin dioxide microspheres was weighed, and 10mL of 1mmol/L Pd (OAc)2In water solution, xenon UV irradiation for 20min to Pd (OAc)2Decomposing, centrifuging at 10000 rpm/min for 5min, separating the residue, washing with deionized water, centrifuging again to separate the residue, and repeating for 2 times;
(5) collecting the final solid, and drying in an oven at 80 ℃ to obtain the Pd-loaded tin dioxide microsphere gas-sensitive sensing material (namely Pd @ SnO)2)。
The XRD pattern of the gas sensing material is similar to that of example 1, and relatively no SnO is loaded2Diffraction peaks near 40 °, 47 °, and 69 ° were from the supported Pd particles. Of the gas-sensitive sensing materialThe SEM image and TEM image results are similar to example 1, and are three-dimensional spherical assembled structures of micron-sized, with the structural units being particles of several tens of nanometers in size.
(6) The gas sensor module 5 was obtained by following the methods of steps (6) to (7) in example 1.
Example 6
(1) 1g of stannous chloride dihydrate, 2g of oxalic acid and 100mL of deionized water are mixed, 0.1mL of concentrated hydrochloric acid (35%) and 2.16g of hydrazine hydrate (50 wt%) are added, and a transparent homogeneous system is formed by stirring;
(2) putting the mixed solution into a reaction kettle, carrying out hydrothermal treatment at 160 ℃ for 20 hours, cooling, and carrying out centrifugal separation;
(3) collecting solid precipitate, adding deionized water, ultrasonically dispersing for 10min, centrifuging again, and collecting, repeating the process for 3 times to obtain stannic oxide microspheres;
(4) 0.1g of the tin dioxide microspheres are weighed and added with 10mL of K with the concentration of 1mmol/L2PtCl4In water solution, irradiating with xenon ultraviolet light for 20min to obtain K2PtCl4Decomposing, centrifuging at 10000 rpm/min for 5min, separating the residue, washing with deionized water, centrifuging again to separate the residue, and repeating for 2 times;
(5) collecting the final solid, and drying in an oven at 80 ℃ to obtain the Pt-loaded tin dioxide microsphere gas-sensitive sensing material (namely Pt @ SnO)2)。
The XRD pattern of the gas sensing material is similar to that of example 1, and relatively no SnO is loaded2Diffraction peaks near 40 °, 47 °, and 69 ° were from the supported Pt particles. The results of SEM and TEM images of the gas sensing material were similar to those of example 1, and were a three-dimensional spherical assembled structure of micron-sized dimensions, and the structural unit was a particle of several tens of nanometers in size.
(6) The gas sensor module 6 was obtained by following the procedures of steps (6) to (7) in example 1.
Test example
The gas sensing modules 1-6 are used for testing, and CO and H to be tested with specified concentration are injected into the polytetrafluoroethylene closed cavity2S and the mixed gas of the S and the S are used for detecting the resistance change of the gas-sensitive material along with the gas injection to obtain corresponding responseThe data and the specific results are shown in tables 1-2 and FIG. 4.
TABLE 1
Figure BDA0001772758890000161
TABLE 2
Figure BDA0001772758890000162
As can be seen from the above tables 1 and 2, the noble metal-loaded gas-sensitive sensing material prepared by changing the kinds of the noble metal salt precursors, the concentration of the solution and other related parameters, the morphology, the microstructure and the CO/H ratio thereof2The response characteristics of S gas have no obvious difference, which shows that the preparation method of the gas sensing module can effectively synthesize a broad-spectrum response material; meanwhile, different metal-loaded tin dioxide is used for CO and H2The S gas shows difference in response sensitivity, can be used for constructing a multi-dimensional complex gas sensor array, and can obtain the composition information of the complex gas through iterative algorithm simulation.
FIG. 4 left panel shows Ag @ SnO obtained in example 12For different concentrations of CO and H2The response curves of S gas and the mixed gas of the S gas and the S gas are shown in the right graph, and the Pd @ SnO obtained in example 5 is shown in the right graph2For different concentrations of CO and H2Response curves of S gas and the mixture of both gases. It can be seen that in a certain concentration interval, Ag @ SnO2And Pd @ SnO2For CO and H2The response of the S gas has approximately linear characteristics, and the response value of the mixed gas is significantly lower than the sum of the responses of the single component gases.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims (14)

1. A method of making a gas sensing module, the method comprising:
1) mixing a tin-containing compound, C2-C6 organic dibasic acid, hydrazine hydrate and hydrochloric acid, carrying out hydrothermal reaction, and then carrying out solid-liquid separation to obtain a tin dioxide carrier;
2) loading noble metal on the tin dioxide carrier by an impregnation method to obtain a noble metal loaded gas-sensitive sensing material;
3) loading the noble metal loaded gas-sensitive sensing material on a microsensor chip;
in the step 1), the tin dioxide carrier is a tin dioxide microsphere with a flower-like structure;
in the step 2), the tin dioxide carrier is impregnated with a noble metal precursor, and ultraviolet irradiation is performed, wherein the noble metal precursor is one or more water-soluble noble metal salts selected from Ag, Au, Pd and Pt, and the ultraviolet irradiation conditions include: the time is 10-60min, and the power is 150-500W.
2. The method according to claim 1, wherein the tin-containing compound is one or more selected from stannous dichloride, stannic chloride, stannous oxide and stannous oxalate.
3. The preparation method according to claim 1, wherein the molar ratio of the tin-containing compound to the organic dibasic acid of C2-C6, the hydrazine hydrate, and the hydrochloric acid is 1: 3-5.5: 3-25: 0.2-0.48.
4. The preparation method according to claim 1, wherein the organic dibasic acid of C2-C6 is selected from one or more of oxalic acid, malonic acid, succinic acid, glutaric acid and adipic acid.
5. The method according to claim 4, wherein the C2-C6 organic dibasic acid is oxalic acid.
6. The preparation method according to claim 1, wherein the conditions of the hydrothermal reaction include: the temperature is 160-200 ℃ and the time is 4-20 h.
7. The method of claim 1 wherein the noble metal precursor is selected from AgNO3、AuCl3、Pd(OAc)2、K2PtCl4、PdCl2And Pd (acac)2One or more of (a).
8. The production method according to claim 1, wherein the noble metal precursor is used in an amount of 0.005 to 0.03 parts by weight in terms of noble metal element, relative to 1 part by weight of the tin dioxide carrier.
9. The manufacturing method of claim 1, wherein the microsensor chip comprises a substrate and a sensing electrode disposed on the substrate.
10. The manufacturing method according to claim 9, wherein the microsensor chip further comprises a heating electrode.
11. The production method according to claim 1, wherein the microsensor chip comprises an electrode layer, an insulating layer, a heating layer, a support layer, a suspended layer, and a substrate layer, which are stacked in this order, and through holes are provided in regions on the suspended layer and the substrate layer that correspond to the heating layer.
12. The production method according to claim 1, wherein the tin dioxide microspheres have a diameter of 0.5 to 2.5 μm.
13. A gas sensing module array, which is characterized by consisting of two gas sensing modules obtained by the preparation method of any one of claims 1 to 12, wherein the gas sensing modules are loaded with different noble metal loaded gas-sensitive sensing materials.
14. Use of a gas sensing module obtained by the preparation method according to any one of claims 1 to 12 or the gas sensing module array according to claim 13 in the field of leak detection, hazardous gas detection or human body protection.
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