阅读说明：本技术 一种基于银纳米颗粒改性碳化钛的场效应晶体管气体传感器及其制备方法与应用 (Silver nanoparticle modified titanium carbide based field effect transistor gas sensor and preparation method and application thereof ) 是由 毛舜 徐齐昆 宗博洋 于 2021-08-27 设计创作，主要内容包括：本发明涉及一种基于银纳米颗粒改性碳化钛的场效应晶体管气体传感器及其制备方法与应用,场效应晶体管气体传感器包括由下至上依次设置的硅栅极、二氧化硅层、叉指电极区,以及银纳米颗粒改性碳化钛层；其中叉指电极区包括以叉指形式分布的源极和/或漏极,相邻的源极与漏极之间通过银纳米颗粒改性碳化钛层电性连接；制备方法包括将银纳米颗粒改性碳化钛水相分散液滴涂于叉指电极区上,干燥后即得到场效应晶体管气体传感器。与现有技术相比,本发明利用碳化钛表面负载的银纳米颗粒与硫化氢间的强化学作用实现对目标气体的快速高效检测,具有沟制备工艺简单、响应灵敏、运行成本低等优点,对场效应晶体管在气体传感器领域的推广具有重要意义。(The invention relates to a field effect transistor gas sensor based on silver nanoparticle modified titanium carbide and a preparation method and application thereof, wherein the field effect transistor gas sensor comprises a silicon gate, a silicon dioxide layer, an interdigital electrode area and a silver nanoparticle modified titanium carbide layer which are sequentially arranged from bottom to top; the interdigital electrode area comprises source electrodes and/or drain electrodes which are distributed in an interdigital mode, and the adjacent source electrodes and the drain electrodes are electrically connected through a silver nanoparticle modified titanium carbide layer; the preparation method comprises the steps of dropwise coating the silver nanoparticle modified titanium carbide aqueous phase dispersion liquid on the interdigital electrode area, and drying to obtain the field effect transistor gas sensor. Compared with the prior art, the method realizes the rapid and efficient detection of the target gas by utilizing the strong chemical action between the silver nanoparticles loaded on the surface of the titanium carbide and the hydrogen sulfide, has the advantages of simple channel preparation process, sensitive response, low operation cost and the like, and has important significance for the popularization of the field effect transistor in the field of gas sensors.)

1. A field effect transistor gas sensor based on silver nanoparticle modified titanium carbide is characterized by comprising a silicon gate (1), a silicon dioxide layer (2), an interdigital electrode area and a silver nanoparticle modified titanium carbide layer (4) which are sequentially arranged from bottom to top;

the interdigital electrode area comprises source electrodes (3) and/or drain electrodes (5) distributed in an interdigital mode, and the adjacent source electrodes (3) and the adjacent drain electrodes (5) are electrically connected through silver nanoparticle modified titanium carbide layers (4).

2. The gas sensor of the field effect transistor based on the silver nanoparticle modified titanium carbide of claim 1, wherein the source electrode (3) and the drain electrode (5) are both gold electrodes.

3. The gas sensor of claim 2, wherein the width of the gold electrode is 1.9-2.1 μm, and the distance between adjacent gold electrodes is 1.4-1.6 μm.

4. A method of manufacturing a field effect transistor gas sensor based on silver nanoparticle modified titanium carbide according to any one of claims 1 to 3, comprising the steps of:

1) mixing silver nitrate and single-layer titanium carbide, and preparing into silver nanoparticle modified titanium carbide aqueous phase dispersion liquid;

2) and (3) dropwise coating the silver nanoparticle modified titanium carbide aqueous phase dispersion liquid on an interdigital electrode area, and drying to obtain the field effect transistor gas sensor.

5. The method for preparing the field effect transistor gas sensor based on the silver nanoparticle modified titanium carbide is characterized in that in the step 1), the mass ratio of silver nitrate to a single layer of titanium carbide is (1-4): 5.

6. The method for preparing the field effect transistor gas sensor based on the silver nanoparticle modified titanium carbide according to claim 4, wherein the step 1) is specifically as follows: and adding a silver nitrate solution into the single-layer titanium carbide dispersion liquid, sequentially stirring and mixing at normal temperature, carrying out ultrasonic treatment and centrifugal washing, and mixing with water to obtain the silver nanoparticle modified titanium carbide aqueous phase dispersion liquid.

7. The method for preparing the field effect transistor gas sensor based on the silver nanoparticle modified titanium carbide is characterized in that the stirring time is 7-8min, the ultrasonic treatment time is 8-12min, and the used washing liquid is ethanol.

8. The method for preparing the field effect transistor gas sensor based on the silver nanoparticle modified titanium carbide, according to claim 4, wherein in the step 2), the mass concentration of the silver nanoparticle modified titanium carbide aqueous phase dispersion liquid is 4-6 μ g/mL, and the dropping coating amount is 0.8-1.2 μ L/mm²。

9. The use of the silver nanoparticle-modified titanium carbide-based field effect transistor gas sensor according to any one of claims 1 to 3, wherein the field effect transistor gas sensor is used for sensing and detecting hydrogen sulfide gas in an atmospheric environment.

10. The application of the silver nanoparticle modified titanium carbide based field effect transistor gas sensor according to claim 9, wherein the sensing detection method comprises the following steps:

1) placing the field effect transistor gas sensor in an air atmosphere with set relative humidity until the current between the source electrode (3) and the drain electrode (5) is stable; introducing hydrogen sulfide/air mixed gas with different concentrations, and monitoring the current change condition between the source electrode (3) and the drain electrode (5) to reflect the response value R (I) of the field effect transistor gas sensor to the hydrogen sulfide with different concentrations_g-I₀)/I₀(ii) a Then, adjusting the relative humidity of the air atmosphere, and repeating the experiment to obtain response-concentration calibration curves under different humidities;

wherein, I₀For the steady current of a field effect transistor gas sensor in an air atmosphere of set relative humidity, I_gIntroducing hydrogen sulfide/air mixed gas into a field effect transistor gas sensor to obtain peak current;

2) measuring the relative humidity of the gas to be measured or the working environment, and selecting a corresponding calibration curve; and (2) obtaining a response value R to the gas to be detected by using the field effect transistor gas sensor by adopting the method in the same step 1), and obtaining the concentration of the hydrogen sulfide gas according to the response value R and the calibration curve.

Technical Field

The invention belongs to the technical field of gas sensors, and relates to a field effect transistor gas sensor based on silver nanoparticle modified titanium carbide, and a preparation method and application thereof.

Background

Hydrogen sulfide is a harmful gas with severe toxicity, strong corrosiveness, flammability and explosiveness, and can cause serious harm to the environment and human health. At present, hydrogen sulfide is mainly used in fluorescent powder synthesis, metal refining, medicine and pesticide production as an important chemical raw material and a chemical reducing agent. In addition, low concentrations of hydrogen sulfide are one of the important respiratory markers for the detection of halitosis. Therefore, the development of an efficient and reliable hydrogen sulfide gas sensor is of great significance.

At present, the commonly used gas detection means mainly comprise a gas chromatography/mass spectrometry analysis technology, a chemiluminescence technology, a Fourier transform infrared spectroscopy technology and the like, and the realization of the detection means mostly depends on corresponding precise analysis instruments, so the detection method has the defects of high detection cost, heavy and easy damage of the instruments, complex detection process, long time consumption and the like, and the practical application is seriously limited. Therefore, it is urgently needed to develop a hydrogen sulfide gas detection method which is rapid in situ, simple and convenient to operate and high in sensitivity.

A Field Effect Transistor (FET) is a novel gas sensor, and has attracted research interest of researchers due to its advantages such as simple manufacturing process, sensitive detection, and good portability. A typical field effect transistor sensor consists of a semiconductor material as the channel material and two metal electrodes as the source and drain, respectively, by which different bias voltages can be applied to the gate electrode to modulate the conductance of the channel. Meanwhile, gas detection can be realized by measuring the change of the drain flow before and after exposure to target gas under constant voltage, and when gas molecules are adsorbed, the electronic structure of the sensing material can be changed, so that the conductance of the sensing material is changed. Channel materials commonly used today include: semiconductor Metal Oxide (MOS), graphene, transition metal chalcogenides (TMDCs), Black Phosphorus (BP), titanium carbide (Ti)₃C₂T_x) And the like, these semiconductor materials have poor selectivity to target gases and are susceptible to ambient temperature and humidity, which severely limits the development of FET gas sensors.

Disclosure of Invention

The invention aims to provide a field effect transistor gas sensor based on silver nanoparticle modified titanium carbide, which is simple and convenient to prepare, sensitive in detection, good in selectivity and stable in work, and a preparation method and application thereof, and is used for solving the problem that the existing gas detection device is poor in trace hydrogen sulfide detection effect.

The purpose of the invention can be realized by the following technical scheme:

the inventor knows that titanium carbide is a two-dimensional nano material with semiconductor characteristics, and has wide application prospects in the field of FET gas sensors due to excellent electronic performance and stability, and hydrophilicity and surface chemical variability brought by surface groups. The layered structure and weak reducibility of the titanium carbide two-dimensional nano material are utilized, silver ions generate self-reduction reaction on the surface of the titanium carbide two-dimensional nano material to prepare silver nanoparticle modified titanium carbide, a complete FET gas sensor is built, and then strong chemical acting force between silver atoms and sulfur atoms is combined, so that the sensor has unique advantages and wide development prospect in hydrogen sulfide gas detection. The concept is as follows:

a photolithographic substrate comprising a silicon wafer and a 300nm thick silicon dioxide layer formed on the silicon wafer, and Si/SiO₂Forming gold interdigital electrodes on the top of the substrate by an optical etching technology to be used as source-drain electrode pairs;

loading silver nanoparticle modified titanium carbide serving as a channel material in a dripping mode in a gold interdigital electrode area to communicate an adjacent source-drain electrode pair;

and the source electrode, the drain electrode and the silicon gate are connected in a back gate type field effect transistor gas sensor mode, so that the concentration of trace hydrogen sulfide can be effectively detected.

The specific scheme is as follows:

a field effect transistor gas sensor based on silver nanoparticle modified titanium carbide comprises a silicon gate, a silicon dioxide layer, an interdigital electrode area and a silver nanoparticle modified titanium carbide layer which are sequentially arranged from bottom to top;

the interdigital electrode area comprises a source electrode and/or a drain electrode which are distributed in an interdigital mode, in a simple way, the field effect transistor gas sensor is formed by butting two gold interdigital electrodes, wherein one electrode is used as the source electrode, the other electrode is used as the drain electrode, and the source electrode and the drain electrode are distributed in an interdigital mode. And the adjacent source electrode and the drain electrode are electrically connected through the silver nanoparticle modified titanium carbide layer.

Furthermore, the source electrode and the drain electrode are both gold electrodes.

Furthermore, the width of the gold electrode is 1.9-2.1 μm, and the distance between adjacent gold electrodes is 1.4-1.6 μm.

A preparation method of a field effect transistor gas sensor based on silver nanoparticle modified titanium carbide comprises the following steps:

1) mixing silver nitrate and single-layer titanium carbide, and preparing into silver nanoparticle modified titanium carbide aqueous phase dispersion liquid;

2) and (3) dropwise coating the silver nanoparticle modified titanium carbide aqueous phase dispersion liquid on an interdigital electrode area (specifically between a source electrode and a drain electrode), and drying to obtain the field effect transistor gas sensor.

Further, in the step 1), the mass ratio of the silver nitrate to the single-layer titanium carbide is (1-4): 5.

Further, the step 1) is specifically as follows: adding a silver nitrate solution into the monolayer titanium carbide dispersion liquid, sequentially stirring, mixing and ultrasonically treating at normal temperature, carrying out self-reduction reaction on silver ions on the surface of the titanium carbide nanosheet to form silver nanoparticles, centrifuging, washing, and mixing with water to obtain the silver nanoparticle modified titanium carbide aqueous phase dispersion liquid. At this time, titanium carbide serves as both a reducing agent for the reaction and a substrate on which silver nanoparticles are supported.

Wherein the stirring time is 7-8min, the ultrasonic treatment time is 8-12min, and the washing liquid is ethanol.

Further, in the step 2), the mass concentration of the silver nanoparticle modified titanium carbide aqueous phase dispersion liquid is 4-6 mu g/mL, and the dripping amount is 0.8-1.2 mu L/mm²。

The application of the field effect transistor gas sensor based on the silver nanoparticle modified titanium carbide comprises the steps of respectively connecting a source electrode, a drain electrode and a silicon gate electrode in the field effect transistor gas sensor with a semiconductor analyzer for analyzing the electronic characteristics and sensing signals of the sensor, and then placing the sensor in a detection gas environment, so that the qualitative and quantitative detection of trace hydrogen sulfide gas in the atmospheric environment can be realized.

The sensing detection method specifically comprises the following steps:

1) placing the field effect transistor gas sensor in an air atmosphere with set relative humidity until the current between the source electrode 3 and the drain electrode 5 is stable; introducing hydrogen sulfide/air mixed gas with different concentrations, and monitoring the current change condition between the source electrode 3 and the drain electrode 5 to reflect the response value R (I) of the field effect transistor gas sensor to the hydrogen sulfide with different concentrations_g-I₀)/I₀(ii) a Then, adjusting the relative humidity of the air atmosphere, and repeating the experiment to obtain response-concentration calibration curves under different humidities;

wherein, I₀For the steady current of a field effect transistor gas sensor in an air atmosphere of set relative humidity, I_gIntroducing hydrogen sulfide/air mixed gas into a field effect transistor gas sensor to obtain peak current;

2) measuring the relative humidity of the gas to be measured or the working environment, and selecting a corresponding calibration curve; and (2) obtaining a response value R to the gas to be detected by using the field effect transistor gas sensor by adopting the method in the same step 1), and obtaining the concentration of the hydrogen sulfide gas according to the response value R and the calibration curve.

When trace hydrogen sulfide gas is introduced into the cavity provided with the field effect transistor gas sensor, the silver nanoparticle-based modified titanium carbide material has strong physical and chemical adsorption effects on hydrogen sulfide molecules, so that the electronic properties of the channel material are changed, and the generated conductance change is reflected by the current change between the source electrode and the drain electrode. The silver nanoparticles enhance the adsorption of hydrogen sulfide on the surface of titanium carbide mainly due to two aspects of electronic sensitization and chemical sensitization, and firstly, the silver nanoparticles catalyze the adsorption and desorption reaction of oxygen-containing groups on the surface of titanium carbide and form a Schottky barrier with the titanium carbide to accelerate the electron transfer, so that the electronic sensitization effect is achieved. Secondly, a large number of silver nanoparticles on the surface of the titanium carbide provide additional binding sites for gas molecules, and the chemical sensitization effect is achieved based on the strong chemical bond effect between silver and sulfur atoms. And fitting response signals caused by measuring hydrogen sulfide with different concentrations to obtain a standard response-concentration curve, and analyzing a current signal value to determine the concentration of the hydrogen sulfide gas in the measured environment.

Furthermore, the detection concentration of the hydrogen sulfide gas is 0.05-10 ppm.

Compared with the prior art, the invention has the following characteristics:

1) based on the working principle of a field effect transistor, silver nanoparticles are doped on the surface of a titanium carbide nanosheet to form a novel channel material, and the material has strong physical and chemical adsorption effects on hydrogen sulfide molecules, so that the response speed, selectivity and environmental stability of a sensor for detecting hydrogen sulfide are further improved;

2) the field effect transistor gas sensor has good linear correlation between the response value of the field effect transistor gas sensor to the target gas and the gas concentration, the sensing and detecting process can be repeated, and stable detection on trace hydrogen sulfide can be realized;

3) the method realizes the rapid and efficient detection of the target gas by utilizing the strong chemical action between the silver nanoparticles loaded on the surface of the titanium carbide and the hydrogen sulfide, has the advantages of simple channel material preparation process, simple sensor structure, sensitive response, low operation cost and the like, and has important significance for the popularization of the field effect transistor in the field of gas sensors.

Drawings

FIG. 1 is a schematic structural diagram of a field effect transistor gas sensor based on silver nanoparticle modified titanium carbide according to the present invention;

FIG. 2 is a schematic diagram of an interdigital electrode;

FIG. 3 is a scanning electron microscope image of the gold interdigital electrode loaded with silver nanoparticle modified titanium carbide in example 1;

FIG. 4 is a dynamic response curve of the FET gas sensor to different concentrations of hydrogen sulfide continuously fed in example 2;

FIG. 5 is a graph comparing the response of the FET gas sensor to different concentrations of hydrogen sulfide in example 2;

FIG. 6 is a graph comparing the detection effect of the FET gas sensor on different concentrations of hydrogen sulfide for different doping amounts of silver nanoparticles in example 3;

FIG. 7 is a graph comparing the response signals of the FET gas sensor to different gases in example 4;

FIG. 8 is a graph of the response-concentration relationship of the FET gas sensor to different concentrations of hydrogen sulfide at different ambient humidity in example 5;

FIG. 9 and FIG. 10 are the self-calibration flow based on the calibration curve of response-concentration (FIG. 8) under different RH and the self-calibration schematic diagram in example 5;

FIG. 11 is a graph illustrating the calibration process based on hydrogen sulfide concentrations at different RH in example 7;

reference numerals:

1-silicon gate, 2-silicon dioxide layer, 3-source electrode, 4-silver nanoparticle modified titanium carbide layer and 5-drain electrode.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

A field effect transistor gas sensor based on silver nanoparticle modified titanium carbide comprises a silicon gate 1, a silicon dioxide layer 2, an interdigital electrode region and a silver nanoparticle modified titanium carbide layer 4 which are sequentially arranged from bottom to top; the interdigital electrode area comprises a source electrode 3 and/or a drain electrode 5 which are distributed in an interdigital mode, a group of interdigital electrode pairs are formed between the adjacent source electrode 3 and the adjacent drain electrode 5 and are electrically connected through a silver nanoparticle modified titanium carbide layer 4.

Specifically, the source electrode 3 and the drain electrode 5 are both gold electrodes, the width of the electrodes is 1.9-2.1 μm, and the distance between the adjacent gold electrodes is 1.4-1.6 μm.

A preparation method of a field effect transistor gas sensor based on silver nanoparticle modified titanium carbide comprises the following steps:

s1: adding a silver nitrate solution into the single-layer titanium carbide dispersion liquid, stirring and mixing for 7-8min at normal temperature, enabling silver ions to perform self-reduction reaction on the surface of the titanium carbide nanosheets to form silver nanoparticles, performing ultrasonic treatment for 8-12min, performing centrifugal washing for 2-3 times by using sewage ethanol, mixing with water, and diluting to 4-6 mu g/mL to obtain a silver nanoparticle modified titanium carbide aqueous phase dispersion liquid; wherein the mass ratio of silver nitrate to single-layer titanium carbide is (1-4) to 5;

s2: the silver nano-particle modified titanium carbide aqueous phase dispersion liquid is added with the concentration of 0.8-1.2 mu L/mm²The coating amount is dripped on the interdigital electrode area, and then the interdigital electrode area is dried in the air at normal temperature, so that the field effect transistor gas sensor is obtained.

The application of the field effect transistor gas sensor based on the silver nanoparticle modified titanium carbide comprises the steps of respectively connecting a source electrode 3, a drain electrode 5 and a silicon gate 1 in the field effect transistor gas sensor with a semiconductor analyzer for analyzing the electronic characteristics and sensing signals of the sensor, and then placing the sensor in a detection gas environment, so that the qualitative and quantitative detection of the trace hydrogen sulfide gas 5 in the atmospheric environment can be realized.

During detection, trace hydrogen sulfide gas is introduced into the cavity provided with the field effect transistor gas sensor, the silver nanoparticle-based modified titanium carbide material has strong physical and chemical adsorption effects on hydrogen sulfide molecules, electronic properties of a channel material are changed, and generated conductance changes are reflected through current changes between the source electrode and the drain electrode. Namely, the concentration of the hydrogen sulfide gas in the tested environment is determined according to the electric signal change recorded by the semiconductor analyzer and the standard response-concentration curve. The preferred detection concentration of hydrogen sulfide gas is 0.05-10 ppm.

The sensing detection method specifically comprises the following steps:

1) placing the field effect transistor gas sensor in an air atmosphere with set relative humidity until the current between the source electrode 3 and the drain electrode 5 is stable; introducing hydrogen sulfide/air mixed gas with different concentrations, and monitoring the current change condition between the source electrode 3 and the drain electrode 5 to reflect the response value R (I) of the field effect transistor gas sensor to the hydrogen sulfide with different concentrations_g-I₀)/I₀(ii) a Then, adjusting the relative humidity of the air atmosphere, and repeating the experiment to obtain response-concentration calibration curves under different humidities;

wherein, I₀As field effect transistor gas sensorsStable current in air atmosphere of set relative humidity, I_gIntroducing hydrogen sulfide/air mixed gas into a field effect transistor gas sensor to obtain peak current;

2) measuring the relative humidity of the gas to be measured or the working environment, and selecting a corresponding calibration curve; and (2) obtaining a response value R to the gas to be detected by using the field effect transistor gas sensor by adopting the method in the same step 1), and obtaining the concentration of the hydrogen sulfide gas according to the response value R and the calibration curve.

The following are more detailed embodiments, and the technical solutions and the technical effects obtained by the present invention will be further described by the following embodiments.

Example 1:

a field effect transistor gas sensor based on silver nanoparticle modified titanium carbide comprises the following steps:

s1: slowly adding 1mL of silver nitrate solution with the concentration of 2/4/8mg/mL into 10mL of single-layer titanium carbide dispersion liquid (XFK 04, Nanjing Xiapong nanometer material science and technology Co., Ltd.) with the concentration of 1mg/mL, magnetically stirring for 8min at normal temperature, and performing ultrasonic treatment for 10min to enable silver ions to generate full self-reduction reaction on the surface of the titanium carbide nanosheet;

s2: the obtained mixed solution is centrifugally washed by absolute ethyl alcohol for 3 times and then diluted to about 5 mu g/mL to respectively obtain Ag1-Ti₃C₂T_x、Ag2-Ti₃C₂T_xAnd Ag3-Ti₃C₂T_xThree silver nanoparticle modified titanium carbide nanosheet aqueous phase dispersion liquids;

s3: sequentially adopting acetone, isopropanol and deionized water to wash the surface of the gold interdigital electrode so as to remove a surface organic layer, and then adopting high-purity argon gas to dry in an air way;

s4: and (3) taking 1 mu L of the dispersion liquid, dripping the dispersion liquid on a channel on the surface of the gold interdigital electrode, and naturally drying the dispersion liquid to obtain the field effect transistor gas sensor based on the silver nanoparticle modified titanium carbide. The scanning electron micrograph is shown in FIG. 3.

The structure of the field effect transistor gas sensor can be seen in fig. 1, which comprises a silicon gate 1 and a surface dioxidePhotolithographic substrate (Si/SiO) of silicon layer 2₂Substrate) on Si/SiO by photolithography₂A plurality of pairs of source electrode 3 and drain electrode 5 electrodes of an interdigital electrode area are formed on the top of the substrate, and a silver nanoparticle modified titanium carbide layer 4 which is arranged in the interdigital electrode area and is used as a channel material for connecting the source electrode 3 and the drain electrode 5.

The thickness of the silicon gate 1 is 500 μm, the thickness of the surface silicon dioxide layer 2 is 300nm, the source electrode 3 and the drain electrode 5 are gold interdigital electrodes, the thickness of the electrodes is 50nm, the width L of the electrodes is about 2 μm, the distance D between the adjacent gold interdigital electrodes is about 1.5 μm (as shown in figure 2), the thickness of the silver nanoparticle modified titanium carbide layer 4 is about 1.5nm, and the sheet diameter is about 2 μm. Ag1-Ti₃C₂T_x、Ag2-Ti₃C₂T_xAnd Ag3-Ti₃C₂T_xThe three silver nanoparticle modified titanium carbide nanosheets are used as channel materials and are respectively communicated with electrode pairs on corresponding materials, so that a complete field effect transistor sensor is constructed.

Example 2:

this example was used to evaluate the field effect transistor gas sensor (Ag 2-Ti) prepared in example 1₃C₂T_x) The evaluation method for the response condition of continuously introducing hydrogen sulfide gas with different concentrations comprises the following steps:

1) placing the field effect transistor gas sensor in a sensor cavity, connecting a source electrode 3 and a drain electrode 5 at two ends of a gold interdigital electrode into a semiconductor analyzer and applying a bias voltage V_ds1V, and simultaneously grounding the silicon gate 1;

2) introducing high-purity air into the sensor cavity until the current between the source electrode 3 and the drain electrode 5 is stable, and recording the stable current I₀；

3) Introducing high-purity Air (Air in the figure) into the sensor cavity until the current between the source electrode 3 and the drain electrode 5 is stabilized to I₀；

4) The high purity air is switched to a high purity air/hydrogen sulfide mixed gas (marked as H in the figure) with a set concentration₂S), monitoring the current I between the source 3 and the drain 5_ds(ii) a change in condition;

5) switching high-purity air/hydrogen sulfide mixed gas to highPure Air (Air in the figure), monitor the current I between the source 3 and the drain 5_ds(ii) a change in condition;

6) and 3) taking the steps 3) to 5) as an experimental stage and repeating the steps, and simultaneously adjusting the mixing proportion of high-purity air and hydrogen sulfide in the mixed gas through a mass flow meter to ensure that the concentration of the hydrogen sulfide in each experimental stage is constant, wherein in the whole evaluation process, the concentration of the hydrogen sulfide is sequentially increased by stages (0.05-10 ppm).

In response to the value R ═ I_ds-I₀)/I₀＝ΔI/I₀Reflecting the response of the sensor to different concentrations of hydrogen sulfide, the resulting real-time response-concentration curve is shown in fig. 4 (the relative humidity of the detection environment in the sensor cavity is 5%).

As can be seen from the figure, the introduction of hydrogen sulfide gas at different concentrations leads to the sensor I_dsThe detection speed of the sensor is fast, and the response value is in positive correlation with the concentration of the hydrogen sulfide gas, so that the field effect transistor gas sensor can be used for detecting trace hydrogen sulfide gas molecules in the atmospheric environment.

Example 3:

this example separately considers field effect transistor gas sensors (Ag 2-Ti)₃C₂T_x) The response condition under the hydrogen sulfide gas environment with different concentrations comprises the following specific processes:

placing multiple field effect transistor gas sensors in corresponding sensor cavities, connecting source 3 and drain 5 at two ends of gold interdigital electrode into semiconductor analyzer, and applying bias voltage V_dsSimultaneously grounding the silicon gate 1 at 1V; introducing high-purity air into the sensor cavities, controlling the proportion of the air introduced into each cavity and hydrogen sulfide through a mass flow controller after signals are stable, controlling the concentration of hydrogen sulfide gas in the sensor cavities to be respectively set at the concentration (0.05-10 ppm) respectively, and monitoring the current I of the two electrodes in real time_dsChanges are made to reflect the response of the sensor to different concentrations of hydrogen sulfide (simultaneity)Example 2, the relative humidity of the sensing environment in the sensor cavity was 5%), and the resulting real-time response-concentration curve is shown in fig. 5.

As can be seen from the figure, the response of the constructed silver nanoparticle modified titanium carbide field effect transistor gas sensor to hydrogen sulfide is linearly related to the concentration.

Example 4:

this example examined various field effect transistor gas sensors (Ag 1-Ti) using the same method as in example 3₃C₂T_x、Ag2-Ti₃C₂T_xAnd Ag3-Ti₃C₂T_x) The response-concentration relation curve of the modified titanium carbide gas sensor with different silver doping amounts is shown in fig. 6 (the relative humidity of the detection environment in the sensor cavity is 5%) under the response conditions of hydrogen sulfide gas environments with different concentrations. Wherein the response value R ═ I_g-I₀)/I₀＝ΔI/I₀，I_gFor the experiment stage I_dsThe peak current of (c).

As can be seen from the figure, the detection sensitivity of the sensor can be changed by adjusting the doping amount of the silver nanoparticles, wherein Ag2-Ti₃C₂T_xThe hydrogen sulfide detection sensitivity is strongest under the test environment.

Example 5:

this example examined a field effect transistor gas sensor (Ag 2-Ti) using the same method as in example 3₃C₂T_x) Response conditions under different gas environments are adopted, and a detection selectivity comparison graph of the sensor on hydrogen sulfide and other gases is obtained (figure 7). The gas to be detected is formaldehyde, ammonia gas, carbon monoxide, ethanol, acetone, hydrogen, nitrogen dioxide and hydrogen sulfide respectively, the concentration of the gas to be detected is 1ppm, the relative humidity of the detection environment in the cavity of the sensor is 5%, and the calculation method of the response value R is the same as that in the embodiment 4.

It can be seen from the figure that the sensor has no obvious response to other selected gases, and the response is obviously increased when hydrogen sulfide is introduced, which is derived from the strong chemical bond effect between the sulfur atoms in the hydrogen sulfide and the silver atoms on the surface of the silver nanoparticle modified titanium carbide, and the high recognition effect of the constructed silver nanoparticle modified titanium carbide field effect transistor gas sensor on the hydrogen sulfide is illustrated.

Example 6:

this example examined a field effect transistor gas sensor (Ag 2-Ti) using the same method as in example 3₃C₂T_x) The response curve of the hydrogen sulfide in different humidity environments and different hydrogen sulfide concentration environments is shown in fig. 8. Wherein, the concentration of hydrogen sulfide is 0.05-2ppm (0.05, 0.2, 1.0, 2.0ppm), the environmental humidity is regulated and controlled by the humidity of the Air (marked as Air) which is firstly introduced in each experimental stage, in particular, the flow ratio of dry Air and wet Air (the dry Air passing through a gas washing bottle) is controlled by a mass flow controller, so that the Relative Humidity (RH) in the cavity sequentially reaches 5%, 20%, 40%, 60% and 80%.

The response-concentration relationship curves under different environmental humidities can be used as response-concentration calibration curves under different RH (the response value R is calculated as in example 4), so as to obtain a self-calibration manner for eliminating the humidity effect as shown in fig. 9 and 10, which mainly includes the following four steps: firstly, obtaining response-concentration calibration curves under different RH; measuring the relative humidity of the operating environment; selecting a corresponding calibration curve; and fourthly, calculating the gas concentration through the calibration curve according to the response value.

This example also examined a field effect transistor gas sensor (Ag 2-Ti) using the same method as in example 3₃C₂T_x) The accuracy of the self-calibration means is applied under different humidity environments, and the specific process is as follows:

introducing a high-purity air/hydrogen sulfide mixed gas with hydrogen sulfide concentration of 0.8ppm and relative humidity of 5% as a gas to be detected into a gas sensor (Ag 2-Ti) containing a field effect transistor₃C₂T_x) Was measured to have an actual response of 4.27%, and the hydrogen sulfide concentration measurement was calculated to be 0.798ppm with an error of only 0.25% based on the response-concentration calibration curve of fig. 8.

Subsequently, the humidity in the sensor cavity is adjusted by the mass flow controller, the actual response of the sensor when RH is 20% to 80% is obtained, and after calculation according to fig. 8, the calibrated hydrogen sulfide concentration measurement value is obtained, and the calibration process is shown in fig. 11. The measurement results are respectively: 0.813, 0.786, 0.821 and 0.83ppm, the error is only 3.75 percent at most, and the accuracy is excellent.

The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.