阅读说明：本技术 一种高灵敏气体检测传感器 (High-sensitivity gas detection sensor ) 是由 李军 于 2020-05-09 设计创作，主要内容包括：本发明涉及一种高灵敏气体检测传感器,其气体检测材料是石墨烯/金属氧化物/金属硫化物构成的高灵敏三元复合气体检测材料,利用金属硫化物在气体检测方面体现出的快速响应时间、金属氧化物纳米颗粒良好的分散性以及石墨烯较大的表面积的特点,通过三者的协同作用,克服了传统单一金属氧化物半导体制备的气体传感器响应度较差、稳定性差和寿命短的问题,并且通过添加复合改性剂使得TiO<Sub>2</Sub>纳米颗粒具有良好的分散性,使得以此三元复合气体检测材料制备的气体检测传感器对于气体的检测具有更高的灵敏度以及更好的选择性和稳定性。(The invention relates to a high-sensitivity gas detection sensor, wherein a gas detection material is a high-sensitivity ternary composite gas detection material consisting of graphene, metal oxide and metal sulfide, the problems of poor responsiveness, poor stability and short service life of a gas sensor prepared by the traditional single metal oxide semiconductor are solved by utilizing the characteristics of quick response time, good dispersibility of metal oxide nanoparticles and larger surface area of graphene, which are embodied in the aspect of gas detection, of the metal sulfide, and the synergistic effect of the three materials, and TiO is added with a composite modifier 2 The nano particles have good dispersibility, so that the gas detection sensor prepared from the ternary composite gas detection material has higher sensitivity, selectivity and stability for gas detection.)

1. A high-sensitivity gas detection sensor sequentially comprises Al from bottom to top₂O₃The metal-based composite gas detection device comprises a substrate, Pd metal interdigital electrodes and a high-sensitivity ternary composite gas detection material, and is characterized in that comb teeth of the interdigital electrodes are distributed in a staggered manner, the gas detection material is coated in gaps among the interdigital electrodes, and Al is added₂O₃Two ends of the substrate are respectively provided with a strip-shaped sensing electrode connected with the interdigital electrode, each strip-shaped sensing electrode is connected with a gold wire, the high-sensitivity ternary composite gas detection material is composed of graphene, metal oxide and metal sulfide, and the metal oxide is TiO₂The metal sulfide is CdS.

2. The highly sensitive gas detection sensor according to claim 1, wherein the highly sensitive ternary complex gas detection material is prepared by the following steps:

preparing graphene oxide by using an improved Hummer method and preparing a graphene oxide solution; and B: preparing a CdS nanowire material; and C: graphene and TiO₂Compounding quantum wires; step D: graphene/TiO₂And preparing the/CdS ternary composite gas detection material film.

3. The high-sensitivity gas detection sensor according to claim 2, wherein the preparation step a of the high-sensitivity ternary composite gas detection material specifically comprises: the graphene oxide prepared by the Hummer method is placed in an oven at 200 ℃ to be heated for 2 hours to partially reduce the prepared graphene oxide, 30mg of graphene oxide is weighed and placed in a small beaker, 20ml of absolute ethyl alcohol is added to carry out ultrasonic oscillation, 8ml of concentrated HCL and 3ml of distilled water are added to continue oscillation for 3 hours, and graphene oxide solution is formed.

4. The high-sensitivity gas detection sensor according to claim 2, wherein the preparation step B of the high-sensitivity ternary composite gas detection material specifically comprises: 20mmol of thiourea and 8mmol of cadmium nitrate were added in this order to 35ml of an ethylenediamine solution, magnetically stirred for one hour, and then the mixed solution was sonicated for 10min to form a uniform solution. Adding the solution into a polytetrafluoroethylene high-pressure autoclave, carrying out hydrothermal treatment for 36 hours at 180 ℃ in an electric oven, after the reaction is finished, naturally cooling the high-pressure autoclave to room temperature, washing a product by centrifugation, deionized water and absolute ethyl alcohol, drying the product by the oven at 50 ℃ to obtain yellow powder, adding 32.8g of the yellow powder into a 50ml conical flask, adding 30ml of deionized water and 10ml of absolute ethyl alcohol into the conical flask, stirring, carrying out ultrasonic treatment for 30min at 200W to obtain a CdS dispersion liquid, carrying out centrifugal collection, and mixing with the absolute ethyl alcohol to obtain an ethanol solution of CdS.

5. The high-sensitivity gas detection sensor according to claim 2, wherein the preparation step C of the high-sensitivity ternary composite gas detection material specifically comprises: adding 1.5-5ml of ethanol and 0.25-1.2ml of graphene oxide solution into a quartz microwave reaction tube, slowly adding 1.3mol of tetrabutyl titanate, stirring for 2 hours, adding a modifier I and a modifier II into the reaction tube to increase the dispersibility of the formed nanoparticles, putting the reaction tube into a microwave reactor, pre-stirring for 30 seconds, reacting for 1.5 hours at 260 ℃, washing a product for 3 times by using absolute ethyl alcohol and distilled water, finally centrifugally collecting, dispersing in ethyl alcohol to obtain graphene/TiO₂The quantum wire ethanol solution comprises a modifier I:

the modifier II is:

6. the high-sensitivity gas detection sensor according to claim 2, wherein the preparation step D of the high-sensitivity ternary composite gas detection material specifically comprises: firstly, graphene and TiO are mixed₂Ethanol solution coating of quantum wire on Al with finger electrode₂O₃Coating the CdS ethanol solution on the graphene/TiO ceramic wafer₂The surface of the ethanol solution of the quantum wire reacts for 1.5h, and the aging is carried out for 100h at the temperature of 150 ℃ to obtain the graphene/TiO₂the/CdS ternary composite gas detection material.

7. The high-sensitivity gas detection sensor according to claim 5, wherein the mass ratio of the modifier I to the modifier II added in the preparation step C of the high-sensitivity ternary composite gas detection material is 1: 2.

8. The highly sensitive gas detection sensor according to claim 6, wherein the preparation step D of the highly sensitive ternary composite gas detection material is graphene/TiO₂The volume ratio of the ethanol solution of the quantum wire to the ethanol solution of the CdS is as follows: 1: 3.5-5.

9. The highly sensitive gas detection sensor according to claim 6, wherein the highly sensitive ternary complex gas detection material is composed of graphene: 0.15-1.48% of TiO₂: 13.40-17.23%, CdS: 82.36-85.12%, and the sum of the mass percentages of the three is 100%.

Technical Field

The invention belongs to the technical field of gas detection sensors, and particularly relates to a gas detection sensor based on a high-sensitivity ternary composite gas detection material, which is excellent in sensitivity, responsiveness and selectivity.

Background

With the development of modern industry and the progress of information science, the sensor, which is a functional component for taking information, is generally regarded as important at home and abroad. The development of sensing technology will lead to a new industrial revolution, and the gas sensor is an important branch and is widely applied to the fields of national defense construction, industrial production, traffic control, disaster alarm, medical monitoring, artificial intelligence, life and universe science. In the field of gas emission and ambient gas composition detection, gas sensors have become indispensable core devices for better and more accurate detection of gas compositions.

The gas detection material is a core component of the gas detection sensor, and when the gas detection material meets specific gas, the physical and chemical properties of the gas detection material change with the change of the type and concentration of the external gas under certain conditions, so that the gas detection material can be used as a sensing device of the gas sensor. The research on gas detection materials is started in the 30s of the 20 th century in China, and at present, with the increasing requirements of modern society on detection, control and alarm of flammable, explosive, toxic and harmful gases, the performance and the type of the gas detection materials are developed to a certain extent. The metal oxide semiconductor is the most common one of the gas detection materials, but the performance thereof has some problems, such as long response recovery time, poor stability, short life, and the like.

A metal sulfide semiconductor gas sensor is a gas sensor prepared by taking a metal sulfide material as a sensitive material, when a metal sulfide semiconductor device is contacted with a detected gas, surface adsorption or other physical and chemical adsorption actions can be generated, the actions can cause the resistance or work function of a gas detection material to change, namely, the resistance or work function is converted into electric signals, and related information such as the existence concentration of the detected gas can be known according to the strength change of the electric signals.

The metal oxide and the graphene are one of the most commonly used gas sensitive materials at present, and are suitable for being used as gas detection materials due to small size, large specific surface area and high surface activity of nanoparticles, for example, nano titanium dioxide can be used for preparing a gas detection element with high sensitivity, but a single nano material gas sensor has poor selectivity on gas, and meanwhile, the nano material is easy to agglomerate in a solvent and has poor dispersibility, so that the prepared nano material particles have non-uniform conditions, and the responsiveness and the sensitivity on gas detection are influenced.

The responsivity and sensitivity of gas detection materials are greatly dependent on the surface structure and catalytic activity of the materials, so that sensitive materials are often modified to improve the performance of sensors, and two methods are generally adopted: firstly, a gas detection material with a special shape and structure is synthesized, so that the specific surface area and the quantum size of the material are increased; and secondly, synthesizing a gas detection material containing a dopant.

Patent CN108181355A discloses a preparation method of a tin disulfide/graphene/tin dioxide ternary composite gas detection material for a nitrogen dioxide gas detection sensor, aiming at NO₂The detection sensitivity of (2) is up to 10ppb, and NO can be detected at low temperature₂High sensitivity, low detection limit gas detection response. However, SnO₂The nano material has relatively high cost and poor chemical stability, and only oleic acid and oleylamine are added as the surfactant in the preparation process, so that SnO is not effectively improved₂As the problem of easy agglomeration of the nano material, the prepared ternary composite nano material has the problem of uneven nano particles, thereby influencing the sensitivity and the responsiveness of gas detection.

Therefore, a high-sensitivity composite gas detection material capable of effectively improving the nanoparticle agglomeration effect and improving the sensitivity, selectivity, responsiveness and stability of the gas detection sensor is urgently needed, so that the prepared gas detection sensor has better performance.

Disclosure of Invention

The invention aims to provide a high-sensitivity gas detection sensor, wherein a gas detection material is a graphene/metal oxide/metal sulfide high-sensitivity ternary composite gas detection material, the problems of long response recovery time, poor stability and short service life of a gas sensor prepared by a traditional single metal oxide semiconductor are solved, and meanwhile, the technical problem that a dispersion liquid of a nano material is easy to agglomerate is solved by adding a composite modifier in the preparation process, so that the gas detection sensor prepared from the ternary composite gas detection material has better sensitivity and responsiveness to gas detection.

A high-sensitivity gas detection sensor from bottom to topIn the order of above is composed of Al₂O₃The metal-based composite gas detection device comprises a substrate, Pd metal interdigital electrodes and a high-sensitivity ternary composite gas detection material, and is characterized in that comb teeth of the interdigital electrodes are distributed in a staggered manner, the gas detection material is coated in gaps among the interdigital electrodes, and Al is added₂O₃Two ends of the substrate are respectively provided with a strip-shaped sensing electrode connected with the interdigital electrode, each strip-shaped sensing electrode is connected with a gold wire, the high-sensitivity ternary composite gas detection material is composed of graphene, metal oxide and metal sulfide, and the metal oxide is TiO₂The metal sulfide is CdS.

Further, the specific preparation steps of the high-sensitivity ternary composite gas detection material comprise:

preparing graphene oxide by using an improved Hummer method and preparing a graphene oxide solution; and B: preparing a CdS nanowire material; and C: graphene and TiO₂Compounding quantum wires; step D: graphene/TiO₂And preparing the/CdS ternary composite gas detection material film.

Further, the preparation step A of the high-sensitivity ternary composite gas detection material specifically comprises the following steps: the graphene oxide prepared by the Hummer method is placed in an oven at 200 ℃ to be heated for 2 hours to partially reduce the prepared graphene oxide, 30mg of graphene oxide is weighed and placed in a small beaker, 20ml of absolute ethyl alcohol is added to carry out ultrasonic oscillation, 8ml of concentrated HCL and 3ml of distilled water are added to continue oscillation for 3 hours, and graphene oxide solution is formed.

Further, the preparation step B of the high-sensitivity ternary composite gas detection material specifically comprises the following steps: 20mmol of thiourea and 8mmol of cadmium nitrate were added in this order to 35ml of an ethylenediamine solution, magnetically stirred for one hour, and then the mixed solution was sonicated for 10min to form a uniform solution. Adding the solution into a polytetrafluoroethylene high-pressure autoclave, carrying out hydrothermal treatment for 36 hours at 180 ℃ in an electric oven, after the reaction is finished, naturally cooling the high-pressure autoclave to room temperature, washing a product by centrifugation, deionized water and absolute ethyl alcohol, drying the product by the oven at 50 ℃ to obtain yellow powder, adding 32.8g of the yellow powder into a 50ml conical flask, adding 30ml of deionized water and 10ml of absolute ethyl alcohol into the conical flask, stirring, carrying out ultrasonic treatment for 30min at 200W to obtain a CdS dispersion liquid, carrying out centrifugal collection, and mixing with the absolute ethyl alcohol to obtain an ethanol solution of CdS.

Further, the preparation step C of the high-sensitivity ternary composite gas detection material specifically comprises the following steps: adding 1.5-5ml of ethanol and 0.25-1.2ml of graphene oxide solution into a quartz microwave reaction tube, slowly adding 1.3mol of tetrabutyl titanate, stirring for 2 hours, adding a modifier I and a modifier II into the reaction tube to increase the dispersibility of the formed nanoparticles, putting the reaction tube into a microwave reactor, pre-stirring for 30 seconds, reacting for 1.5 hours at 260 ℃, washing a product for 3 times by using absolute ethyl alcohol and distilled water, finally centrifugally collecting, dispersing in ethyl alcohol to obtain graphene/TiO₂The quantum wire ethanol solution comprises a modifier I:

the modifier II is:

further, the preparation step D of the high-sensitivity ternary composite gas detection material specifically comprises the following steps: firstly, graphene and TiO are mixed₂Ethanol solution coating of quantum wire on Al with finger electrode₂O₃Coating the CdS ethanol solution on the graphene/TiO ceramic wafer₂The surface of the ethanol solution of the quantum wire reacts for 1.5h, and the aging is carried out for 100h at the temperature of 150 ℃ to obtain the graphene/TiO₂the/CdS ternary composite gas detection material.

Further, the mass ratio of the modifier I and the modifier II added in the step C for preparing the high-sensitivity ternary composite gas detection material is 1: 2.

Further, in the step D of preparing the high-sensitivity ternary composite gas detection material, graphene/TiO is adopted₂The volume ratio of the ethanol solution of the quantum wire to the ethanol solution of the CdS is as follows: 1: 3.5-5.

Further, the high sensitivity IIIThe component composite gas detection material comprises graphene: 0.15-1.48% of TiO₂: 13.40-17.23%, CdS: 82.36-85.12%, and the sum of the mass percentages of the three is 100%.

The invention has the beneficial effects that:

1. the high-sensitivity gas detection sensor prepared by the invention utilizes the ternary composite gas detection material, and has better sensitivity and selectivity compared with the method that a single metal oxide or metal sulfide or graphene is independently used as the gas detection material.

2. The invention is used for preparing graphene/TiO₂When the quantum wire ethanol solution is used, a modifier I and a modifier II are added to serve as composite modifiers, and the nano graphene/TiO is treated by the silicon-series composite modifiers₂The dispersion system can improve lipophilicity of the formed nano material and effectively increase graphene/TiO₂The quantum wires are used as the dispersibility of the nano material in ethanol, and are beneficial to the uniform coating with a CdS ethanol solution, so that the sensitivity and the responsiveness of the synthesized ternary composite gas detection material are further improved.

3. The modifier I and the modifier II are not optional, and not all dispersing agents or active agents can achieve the technical effect of the invention after being mixed, and the invention can effectively improve the dispersibility of the nano material in a solvent compared with a single modifier by greatly realizing the synergistic effect of the modifier I and the modifier II as the composite modifier, thereby being more beneficial to the sensitivity and the responsiveness of the composite gas detection material.

Drawings

Fig. 1 is a schematic structural view of a high-sensitivity gas detection sensor.

FIG. 2 is a transmission electron microscope (SEM) picture of the ternary composite gas detection material prepared in example 1.

FIG. 3 is a graph showing the results of a gas sensor made of the ternary composite gas detecting material prepared in example 1 with respect to 30ppm of ethanol gas, 200ppm of toluene, 200ppm of acetone, and 200ppm of NO₂200ppm NO gas.

FIG. 4 is a dynamic response curve of the ternary composite sensing material prepared in example 1 for 0.005ppm, 0.05ppm, 10ppm, 30ppm, 50ppm, 100pmm, 200ppm ethanol gas.

FIG. 5 is a graph showing the responsivity of the ternary complex gas detection materials prepared in example 1 and comparative examples 1 to 5 with respect to 200ppm of ethanol gas.

In fig. 1: al (Al)₂O₃A substrate 1, a Pd metal interdigital electrode 2 and a high-sensitivity ternary composite gas detection material 3

Detailed Description