Titanium dioxide-based memristor type gas sensor as well as preparation method and application thereof

Abstract

The invention discloses a titanium dioxide-based memristor type gas sensor and a preparation method and application thereof, the preparation method comprises the following steps: cleaning and drying a substrate, using a high-temperature-resistant Kapton adhesive tape to cover a partial region on one side of a conductive surface of the substrate, and using the covered region as a reserved bottom electrode contact region; adding a titanium source and a fluorine-containing titanium source into the HCl aqueous solution to prepare a precursor solution; the treated substrate is obliquely placed in a steel lining polytetrafluoroethylene reaction kettle, the precursor solution is poured into the reaction kettle, the substrate is completely immersed in the precursor solution, and a hydrothermal reaction is carried out; after the reaction is finished, cooling, cleaning and drying; annealing treatment, and cooling after annealing; depositing an Au electrode; and removing the Kapton adhesive tape on the surface of the substrate to obtain the titanium dioxide-based memristor type gas sensor. According to the titanium dioxide-based memristor type gas sensor prepared by the invention, the response value to TEA under a room temperature condition and a high resistance state reaches up to 38.7, and the titanium dioxide-based memristor type gas sensor has second-level response / recovery and good TEA selectivity and stability.

Description

Technical Field

[0001] The present invention relates to the technical field of gas sensors, and in particular to a titanium dioxide-based memristive gas sensor and a preparation method and application thereof. Background Art

[0002] Triethylamine (TEA) is an important organic reagent used in the synthesis of various organic compounds, including pharmaceuticals, fuels, dyes, and surfactants. However, TEA is volatile, flammable, and toxic, and long-term exposure to TEA vapor at certain concentrations can have adverse effects on human health. Therefore, it is necessary to develop a gas sensor that can quickly and effectively detect low concentrations of TEA.

[0003] In recent years, researchers have focused on exploring highly sensitive TEA-sensitive materials and developing high-performance TEA sensors through various material modification methods. For example, noble metal modification enhances surface catalytic activity and lowers the gas dissociation barrier; doping introduces defect states to regulate the Fermi level position and optimize surface charge transfer efficiency; and composite materials construct heterogeneous interfaces to accelerate the gas adsorption-desorption kinetic equilibrium process. While some research has achieved low-temperature detection of TEA, the lower limit of gas concentration recognition is high, making it difficult to set the sensor's optimal operating temperature to room temperature, and the recovery time is typically tens of seconds.

[0004] Low-temperature detection still requires the integration of a low-temperature heating circuit, hindering the miniaturization and integration of sensors. The high lower limit for gas concentration detection reduces early warning response speed, increasing safety risks. Long recovery times make real-time system-level monitoring difficult. To further improve the technical performance of gas sensors across multiple aspects, breakthroughs must be made in the device structure and surface conductivity-based gas sensing mechanisms of traditional thin-film sensors. Research is needed to develop a memristive gas sensor capable of highly sensitive detection of low-concentration triethylamine gas at room temperature, along with a corresponding fabrication method. This has significant application value for ensuring industrial production and personal safety. Summary of the Invention

[0005] The present invention provides a titanium dioxide-based memristive gas sensor and a preparation method and application thereof to solve the above problems.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] A method for preparing a titanium dioxide-based memristive gas sensor comprises the following steps:

[0008] S1: After cleaning and drying the substrate, use high-temperature resistant Kapton tape to cover part of the conductive surface of the substrate. The covered area serves as the reserved bottom electrode contact area. Ensure that the tape edge is flat and free of bubbles, and completely isolate the covered area. The uncovered area serves as the non-contact area.

[0009] S2: adding a titanium source and a fluorine-containing titanium source to an aqueous HCl solution, stirring and mixing, to prepare a precursor solution;

[0010] S3: Place the substrate treated in S1 at an angle in a steel-lined polytetrafluoroethylene reactor, pour the precursor solution into the reactor until the precursor solution completely covers the substrate, and then place the reactor in an oven for hydrothermal reaction;

[0011] S4: Cooling, cleaning and drying the substrate after the hydrothermal reaction;

[0012] S5: placing the dried substrate in a muffle furnace for air annealing. After annealing, cooling to room temperature, TiO2 nanosheets with nanometer-scale thickness are deposited on the non-contact area of ​​the conductive surface of the substrate, i.e., the sensitive layer.

[0013] S6: depositing a dense film of Au nanoparticles on the sensitive layer as the top electrode;

[0014] S7: removing the Kapton tape on the surface of the substrate to obtain the titanium dioxide-based memristive gas sensor.

[0015] Furthermore, the titanium source is tetrabutyl titanate, and the added amount is 0.3-0.7 mL;

[0016] The fluorine-containing titanium source is ammonium fluorotitanate, and the added amount is 1-5 mmol.

[0017] Furthermore, the temperature of the hydrothermal reaction is 140-200° C., and the time is 10-20 h.

[0018] Furthermore, the concentration of the HCl aqueous solution is 1 mol / L;

[0019] The amount of the HCl aqueous solution used is sufficient to ensure that the precursor solution completely covers the substrate.

[0020] Furthermore, during annealing in S5, the temperature was raised to a target temperature of 500°C at a heating rate of 5°C / min, kept at that temperature for 1 hour, and then naturally cooled to room temperature in the furnace.

[0021] Furthermore, the deposition process described in S6 is: using a mask with circular openings, an argon flow rate of 24 sccm, a base pressure in the chamber of 1 μTorr, a working pressure of 5 mTorr, a sputtering power of 30 W, and a sputtering time of 3 min.

[0022] Furthermore, the diameter of the circular opening is less than 0.5 cm.

[0023] Furthermore, in S4, the specific steps of cooling, cleaning and drying the sample are as follows: the sample after reaction cooling is cleaned in appropriate amounts of deionized water and anhydrous ethanol for no less than 3 times, respectively, and then dried in a nitrogen cabinet after cleaning.

[0024] Furthermore, the volume of the steel-lined polytetrafluoroethylene reactor is more than 1.6 times the volume of the precursor solution, so as to reserve space to buffer the pressure and avoid lining rupture.

[0025] Another aspect of the present invention provides a titanium dioxide-based memristive gas sensor prepared by the above-mentioned method for preparing a titanium dioxide-based memristive gas sensor, comprising a substrate, a sensitive layer deposited on a non-contact area of ​​a conductive surface of the substrate, and a top electrode deposited on top of the sensitive layer;

[0026] The surface morphology of the sensitive layer is TiO2 nanosheets with nanometer thickness, and the top electrode is a dense film formed by Au nanoparticles.

[0027] Another aspect of the present invention provides an application of the titanium dioxide-based memristive gas sensor in detecting triethylamine at room temperature.

[0028] The beneficial effects of the present invention are:

[0029] The present invention discloses a titanium dioxide-based memristive gas sensor, a preparation method and an application thereof. The preparation method of the memristive gas sensor uses a titanium source that can provide a stable titanium source supply, promote the formation of a dense underlying TiO2 film, ensure the bonding strength of the electrode interface, and the fluorine ions in the fluorine-containing titanium source can induce anisotropic growth of the crystal plane, drive the vertical growth of TiO2 nanosheets on the substrate, and form a three-dimensional hierarchical structure, so that the prepared TiO2 nanosheet sensitive layer is loosely arranged and has a large specific surface area, which is beneficial to the diffusion of gas molecules, thereby helping to improve the gas-sensitive performance; the titanium dioxide-based memristive gas sensor prepared in the present application has a response value of up to 38.7 to TEA in a high-resistance state under room temperature conditions, and has a response / recovery in seconds and good TEA selectivity and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 This is a scanning electron microscope image of the sensitive layer of the titanium dioxide-based memristive gas sensor under the process parameters in Example 1 of the present invention;

[0032] Figure 2Graph showing the gas-sensitive response of the titanium dioxide-based memristive gas sensor to 1 ppm TEA in high and low resistance states in Example 1 of the present invention;

[0033] Figure 3 This is a result diagram of multiple responses of the titanium dioxide-based memristive gas sensor to different concentrations of TEA in Example 1 of the present invention;

[0034] Figure 4 Response graph of the titanium dioxide-based memristive gas sensor in Example 1 of the present invention to six different 1 ppm reducing gases;

[0035] Figure 5 This is a recovery diagram of the titanium dioxide-based memristive gas sensor in Example 1 of the present invention under voltage scanning mode. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0037] Example 1:

[0038] A method for preparing a titanium dioxide-based memristive gas sensor comprises the following steps:

[0039] S1: Ultrasonic clean the FTO substrate with a specification of 20×20×5mm in isopropyl alcohol, acetone, anhydrous ethanol and deionized water in turn, with each cleaning time of 20 minutes. After the FTO substrate is cleaned, dry it in a nitrogen cabinet. Use a high-temperature resistant Kapton tape with a width of 4mm to cover part of the area on the conductive side of the FTO substrate. The covered area is used as the reserved bottom electrode contact area. Ensure that the edge of the tape is flat and free of bubbles, and completely isolate the covered area; the uncovered area is used as a non-contact area; the size of the FTO substrate described in actual application can be adjusted to meet actual needs; the amount of isopropyl alcohol, acetone, anhydrous ethanol and deionized water is sufficient to fully immerse the FTO substrate;

[0040] S2: Prepare the precursor solution: Use 1 mol / L HCl aqueous solution as the solvent (the amount of HCl aqueous solution is sufficient to completely immerse the FTO substrate in the precursor solution), add 0.4 mL of tetrabutyl titanate and 2.5 mmol of ammonium fluorotitanate to the solvent in sequence, and stir magnetically for 30 min until the mixture is uniform;

[0041] S3: The FTO substrate (conductive side down) cleaned and taped was placed in a steel-lined Teflon autoclave at an angle of 45°, then the precursor solution was poured into the inner liner, the precursor solution completely covered the FTO substrate, and the autoclave was sealed; then the autoclave was placed in an oven for hydrothermal reaction, the temperature was 180℃, and the time was 13h; the volume of the steel-lined Teflon autoclave was 1.6 times the volume of the precursor solution to reserve space to buffer pressure and avoid the inner liner from breaking;

[0042] S4: The sample after reaction cooling was cleaned in deionized water and anhydrous ethanol for 3 times respectively, and then dried in a nitrogen cabinet;

[0043] S5: The dried sample was placed in a muffle furnace for air annealing treatment: the temperature was increased to 500℃ at a rate of 5℃ / min, and then the furnace was naturally cooled to room temperature, and a nanoscale thickness of TiO2 nanosheet layer, i.e. a sensitive layer, was deposited in a non-contact area;

[0044] S6: A gold (Au) top electrode was deposited on the sensitive layer, and the deposition process was as follows: a mask plate with a circular opening was selected, the circular opening mask plate aperture was less than 0.5cm, the argon flow was 24sccm, the basic pressure in the sputtering chamber was 1μTorr, the working pressure was 5mTorr, the sputtering power was 30W, and the sputtering time was 3min;

[0045] S7: Finally, the Kapton tape on the surface of the FTO substrate was removed, and the preparation of the titanium dioxide-based memristive gas sensor was completed.

[0046] Performance test:

[0047] The performance test conditions were: the environmental temperature was 25℃, and the relative humidity was 30%.

[0048] Figure 1 The scanning electron microscope image of the sensitive layer of the titanium dioxide-based memristive gas sensor prepared in this embodiment can be seen that the sample surface is composed of titanium dioxide nanosheet stacks with a width of nanoscale, and no other nano-morphology is observed, indicating that the high yield of this microstructure is obtained under the preparation method;

[0049] The titanium dioxide-based memristive gas sensor prepared in this embodiment was used to detect 1ppm TEA at room temperature, and the results are shown in Figure 2 As can be seen from the figure, the titanium dioxide-based memristive gas sensor has a gas sensitive response to 1ppm TEA in high and low resistance states, and the device shows a stronger current change in the high resistance state (HRS), with a response value as high as 38.7, while the response value in the low resistance state (LRS) is only 8.6, indicating that the titanium dioxide-based memristive gas sensor is more sensitive to TEA in the high resistance state;

[0050] like Figure 3 The figure shows the response results of the titanium dioxide-based memristive gas sensor at different concentrations of TEA (1ppm, 2.5ppm, 7.5ppm, 10ppm). The results show that the response value increases with the increase of gas concentration. For the same concentration of TEA, the response error is less than 1.87, indicating that the titanium dioxide-based memristive gas sensor has good stability.

[0051] Figure 4 The response results of the titanium dioxide-based memristive gas sensor to six different 1ppm reducing gases are shown in Figure 2. Figure 4 In the experiment, the response values ​​of the titanium dioxide-based memristive gas sensor to TEA were 3.5 times that of NH3, 15.9 times that of methanol, 16.3 times that of ethanol, 17.8 times that of acetone and 16.5 times that of isopropanol, indicating that the device has good TEA selectivity.

[0052] Figure 5 This is the recovery diagram of the titanium dioxide-based memristive gas sensor in voltage scanning mode, as shown in Figure 5 As shown, it takes only 0.8s from applying the scanning voltage to the baseline resistance returning to the initial state, indicating that the device can achieve ultrafast recovery, thereby improving the real-time and dynamic response capabilities of gas detection.

[0053] Example 2:

[0054] A method for preparing a titanium dioxide-based memristive gas sensor comprises the following steps:

[0055] S1: Ultrasonic clean the FTO substrate with a specification of 20×20×5mm in isopropyl alcohol, acetone, anhydrous ethanol and deionized water in turn, with each cleaning time of 20 minutes. After the FTO substrate is cleaned, dry it in a nitrogen cabinet. Use a high-temperature resistant Kapton tape with a width of 4mm to cover part of the area on the conductive side of the FTO substrate. The covered area is used as the reserved bottom electrode contact area. Ensure that the edge of the tape is flat and free of bubbles, and completely isolate the covered area. The size of the FTO substrate described in actual application can be adjusted to meet actual needs. The amount of isopropyl alcohol, acetone, anhydrous ethanol and deionized water is sufficient to completely immerse the FTO substrate.

[0056] S2: Prepare the precursor solution: Use 1 mol / L HCl aqueous solution as the solvent (the amount of HCl aqueous solution is sufficient to completely immerse the FTO substrate in the precursor solution), add 0.3 mL of tetrabutyl titanate and 2.5 mmol of ammonium fluorotitanate to the solvent in sequence, and stir magnetically for 30 min until the mixture is uniform;

[0057] S3: Place the cleaned, dried, and taped FTO substrate (conductive surface facing down) at a 45° angle in a steel-lined polytetrafluoroethylene reactor. Pour the precursor solution into the liner until the precursor solution completely covers the FTO substrate, and seal the stainless steel reactor. The reactor is then placed in an oven for a hydrothermal reaction at 180°C for 13 hours.

[0058] S4: After cooling, the sample was washed three times in appropriate amounts of deionized water and anhydrous ethanol, and then dried in a nitrogen cabinet.

[0059] S5: The dried sample is placed in a muffle furnace for air annealing: the temperature is raised to the target temperature of 500°C at a heating rate of 5°C / min, kept at this temperature for 1 hour, and then naturally cooled to room temperature in the furnace. Nano-thick TiO2 nanosheets are deposited on the non-contact area of ​​the conductive surface of the FTO substrate;

[0060] S6: depositing a gold (Au) top electrode, wherein the specific deposition process is as follows: selecting a mask with a circular opening, the aperture of the circular opening mask is less than 0.5 cm, the argon flow rate is 24 sccm, the base pressure in the chamber is 1 μTorr, the working pressure is 5 mTorr, the sputtering power is 30 W, and the sputtering time is 3 min;

[0061] S7: Finally, remove the Kapton tape on the surface of the FTO substrate to complete the preparation of the titanium dioxide-based memristive gas sensor.

[0062] The surface of the titanium dioxide-based memristive gas sensor obtained under the process parameters of this embodiment is still composed of titanium dioxide nanosheets with a width of micrometers. The response value of this titanium dioxide-based memristive gas sensor to 1ppm TEA is 30.5, and the response values ​​to TEA are 2.8, 10.2, 11.4, 13.2 and 12.8 times that of 1ppm NH3, methanol, ethanol, acetone and isopropanol, respectively, indicating that the TEA gas-sensing performance and selectivity of the device are not as good as those of Example 1. That is, after reducing the amount of tetrabutyl titanate, the gas-sensing performance and selectivity will be reduced, but it is still better than the sensors of the prior art (TiO2-based gas sensors reported in the past two years generally have an operating temperature above 200°C, a response to 100ppm TEA of less than 10, and a response recovery time of tens of seconds).

[0063] Example 3:

[0064] A method for preparing a titanium dioxide-based memristive gas sensor comprises the following steps:

[0065] S1: Ultrasonic clean a 20 × 20 × 5 mm FTO substrate in isopropyl alcohol, acetone, anhydrous ethanol, and deionized water, sequentially for 20 minutes each time. After cleaning, dry the FTO substrate in a nitrogen cabinet. Use 4 mm wide high-temperature Kapton tape to cover a portion of the conductive surface of the FTO substrate. The covered area will serve as the reserved bottom electrode contact area. Ensure that the tape edge is flat and free of bubbles, and completely isolate the covered area.

[0066] S2: Prepare the precursor solution: Use 1 mol / L HCl aqueous solution as the solvent (the amount of HCl aqueous solution is sufficient to completely immerse the FTO substrate in the precursor solution), add 0.4 mL of tetrabutyl titanate and 5 mmol of ammonium fluorotitanate to the solvent in sequence, and stir magnetically for 30 min until the mixture is uniform;

[0067] S3: Place the cleaned, dried, and taped FTO substrate (conductive surface facing down) at a 45° angle in a steel-lined polytetrafluoroethylene reactor. Pour the precursor solution into the liner until the precursor solution completely covers the FTO substrate, and seal the stainless steel reactor. The reactor is then placed in an oven for a hydrothermal reaction at 180°C for 13 hours.

[0068] S4: After cooling, the sample was washed three times in appropriate amounts of deionized water and anhydrous ethanol, and then dried in a nitrogen cabinet.

[0069] S5: The dried sample is placed in a muffle furnace for air annealing: the temperature is raised to the target temperature of 500°C at a heating rate of 5°C / min, kept at this temperature for 1 hour, and then naturally cooled to room temperature in the furnace. Nano-thick TiO2 nanosheets are deposited on the non-contact area of ​​the conductive surface of the FTO substrate;

[0070] S6: depositing a gold (Au) top electrode, wherein the deposition process is as follows: selecting a mask with a circular opening, the aperture of the circular opening of the mask is less than 0.5 cm, the argon flow rate is 24 sccm, the base pressure in the chamber is 1 μTorr, the working pressure is 5 mTorr, the sputtering power is 30 W, and the sputtering time is 3 min;

[0071] S7: Finally, remove the Kapton tape on the surface of the FTO substrate to complete the preparation of the titanium dioxide-based memristive gas sensor.

[0072] The surface of the titanium dioxide-based memristive gas sensor obtained under the process parameters of this embodiment is still composed of titanium dioxide nanosheets with a width of micrometers. The titanium dioxide-based memristive gas sensor has a response value of 24.8 to 1 ppm TEA, and its response values ​​to TEA are 1.5, 9.9, 8.3, 8.8, and 9.5 times that of 1 ppm NH3, methanol, ethanol, acetone, and isopropanol, respectively. This indicates that the device's TEA gas-sensing performance and selectivity are inferior to those of Examples 1 and 2. In other words, increasing the amount of ammonium fluorotitanate reduces the device's TEA gas-sensing performance and selectivity, but it still outperforms existing gas sensors.

[0073] Example 4: Effect of the Addition Amount of Tetrabutyl Titanate on the Performance of the Prepared Titanium Dioxide-Based Memristive Gas Sensor

[0074] In order to explore the optimal addition amount of tetrabutyl titanate, a total of 4 control groups were set up in this embodiment for comparison with Example 1. The addition amount of tetrabutyl titanate in the control group was gradually increased in a gradient of 0.1 ml, that is, the addition amount of tetrabutyl titanate in the control group was 0.3 ml, 0.5 ml, 0.6 ml, and 0.7 ml, respectively. The remaining steps were exactly the same as those in Example 1 to prepare multiple groups of titanium dioxide-based memristive gas sensors.

[0075] The gas-sensitive response results of multiple groups of titanium dioxide-based memristive gas sensors prepared in this embodiment to 1 ppm TEA are shown in Table 1 below.

[0076] Table 1 Gas-sensitive response results of multiple groups of titanium dioxide-based memristive gas sensors prepared in Example 3 to TEA

[0077]

[0078] As can be seen from the results in Table 1, the response values ​​of the control groups 1-4 in this embodiment are lower than the response values ​​of Example 1, but are all better than the effects of the existing gas sensors; among them, the device with an addition amount of 0.4 ml of tetrabutyl titanate (Example 1) shows the best gas-sensitive response to TEA, that is, the optimal addition amount of tetrabutyl titanate is 0.4 ml.

[0079] Example 5: Effect of the Amount of Ammonium Fluotitanate on the Performance of the Prepared Titanium Dioxide-Based Memristive Gas Sensor

[0080] In order to explore the optimal addition amount of ammonium fluorotitanate, a total of 8 control groups were set up in this embodiment for comparison with Example 1. The addition amount of ammonium fluorotitanate in the control group was gradually increased with a gradient of 0.5 mmol, that is, the addition amount of ammonium fluorotitanate in the control group was 1 mmol, 1.5 mmol, 2 mmol, 3 mmol, 3.5 mmol, 4 mmol, 4.5 mmol, and 5 mmol, respectively. The remaining steps were exactly the same as those in Example 1 to prepare multiple groups of titanium dioxide-based memristive gas sensors.

[0081] The gas-sensitive response results of multiple groups of titanium dioxide-based memristive gas sensors prepared in this embodiment to 1 ppm TEA are shown in Table 2 below.

[0082] Table 2 Gas-sensitive response results of multiple groups of titanium dioxide-based memristive gas sensors prepared in Example 4 to TEA

[0083]

[0084] As can be seen from the results in Table 2, the response values ​​of the control groups 1-8 in this embodiment are lower than the response values ​​of Example 1, but are also better than the effects of existing gas sensors; among them, the device with an addition amount of 2.5 mmol of ammonium fluorotitanate (Example 1) shows the best gas-sensitive response to TEA, that is, the optimal addition amount of ammonium fluorotitanate is 2.5 mmol.

[0085] Example 6: Effect of hydrothermal time on the performance of prepared titanium dioxide-based memristive gas sensor

[0086] In order to explore the effect of hydrothermal time on device performance, a total of 10 control groups were set up in this embodiment for comparison with Example 1. The hydrothermal time in the control group was gradually increased with a gradient of 1 hour. The hydrothermal time of each control group was 10 hours, 11 hours, 12 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, and 20 hours, respectively. The remaining steps were exactly the same as those in Example 1 to prepare multiple groups of titanium dioxide-based memristive gas sensors.

[0087] The gas-sensitive response results of multiple groups of titanium dioxide-based memristive gas sensors prepared in this embodiment to 1 ppm TEA are shown in Table 3 below.

[0088] Table 3 Gas-sensitive response results of multiple groups of titanium dioxide-based memristive gas sensors prepared in Example 6 to TEA

[0089]

[0090] From the results of Table 3, it can be seen that the response values of the control groups 1-10 in this embodiment are lower than those of Example 1, but are also better than the effects of existing gas sensors; among them, the device under the hydrothermal time of 13h (Example 1) shows the best gas-sensitive response to TEA, that is, the optimal hydrothermal reaction time is 13h.

[0091] Example 7: Influence of hydrothermal temperature on the performance of the prepared titanium dioxide-based memristive gas sensor

[0092] In order to explore the influence of hydrothermal temperature on the performance of the device, six groups of control groups were set in this embodiment to compare with Example 1. The hydrothermal temperature was set to gradually increase by 10℃ in the control groups, and the hydrothermal temperatures of each control group were 140℃, 150℃, 160℃, 170℃, 190℃ and 200℃, respectively. The remaining steps were the same as those of Example 1, and multiple groups of titanium dioxide-based memristive gas sensors were prepared.

[0093] The 1ppm TEA gas-sensitive response results of the multiple groups of titanium dioxide-based memristive gas sensors prepared in this embodiment are shown in Table 4 as follows:

[0094] Table 4: TEA gas-sensitive response results of the multiple groups of titanium dioxide-based memristive gas sensors prepared in Example 7

[0095]

[0096]

[0097] From the results of Table 4, it can be seen that the response values of the control groups 1-6 in this embodiment are lower than those of Example 1, but are also better than the effects of existing gas sensors; among them, the device under the hydrothermal temperature of 180℃ (Example 1) shows the best gas-sensitive response to TEA, that is, the optimal hydrothermal reaction temperature is 180℃.

[0098] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for part or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a titanium dioxide-based memristive gas sensor, characterized in that: The steps include: S1: After the substrate is cleaned and dried, a high-temperature resistant Kapton tape is used to cover part of the conductive surface of the substrate. The covered area is used as the reserved bottom electrode contact area, and the uncovered area is used as the non-contact area. S2: adding a titanium source and a fluorine-containing titanium source to an aqueous HCl solution, stirring and mixing, to prepare a precursor solution; S3: Place the substrate treated in S1 at an angle in a steel-lined polytetrafluoroethylene reactor, pour the precursor solution into the reactor until the precursor solution completely covers the substrate, and then place the reactor in an oven for hydrothermal reaction; S4: Cooling, cleaning and drying the substrate after the hydrothermal reaction; S5: The dried substrate is placed in a muffle furnace for air annealing. After the annealing is completed, it is cooled to room temperature and TiO2 nanosheets with a thickness of nanometers are deposited in the non-contact area, i.e., the sensitive layer. S6: depositing a dense film of Au nanoparticles on the sensitive layer as the top electrode; S7: removing the Kapton tape on the surface of the substrate to obtain the titanium dioxide-based memristive gas sensor.

2. The method for preparing a titanium dioxide-based memristive gas sensor according to claim 1, wherein: The titanium source is tetrabutyl titanate, and the amount added is 0.3-0.7 mL; The fluorine-containing titanium source is ammonium fluorotitanate, and the added amount is 1-5 mmol.

3. The method for preparing a titanium dioxide-based memristive gas sensor according to claim 1, wherein: The temperature of the hydrothermal reaction is 140-200° C., and the time is 10-20 hours.

4. The method for preparing a titanium dioxide-based memristive gas sensor according to claim 1, wherein: The concentration of the HCl aqueous solution is 1 mol / L.

5. The method for preparing a titanium dioxide-based memristive gas sensor according to claim 1, wherein: During annealing in S5, the temperature was raised to the target temperature of 500°C at a heating rate of 5°C / min, kept at that temperature for 1 hour, and then naturally cooled to room temperature in the furnace.

6. The method for preparing a titanium dioxide-based memristive gas sensor according to claim 1, wherein: The deposition process described in S6 is: using a mask with circular openings, an argon flow rate of 24 sccm, a base pressure in the chamber of 1 μTorr, a working pressure of 5 mTorr, a sputtering power of 30 W, and a sputtering time of 3 min.

7. The method for preparing a titanium dioxide-based memristive gas sensor according to claim 6, characterized in that: The diameter of the circular opening is less than 0.5 cm.

8. The method for preparing a titanium dioxide-based memristive gas sensor according to claim 1, wherein: In S4, the specific steps of cooling, cleaning and drying the sample are as follows: the sample after reaction cooling is cleaned in appropriate amounts of deionized water and anhydrous ethanol for no less than 3 times, and then dried in a nitrogen cabinet after cleaning.

9. A titanium dioxide-based memristive gas sensor prepared by the method for preparing a titanium dioxide-based memristive gas sensor according to claim 1, characterized in that: It includes a substrate, a sensitive layer deposited on a non-contact area of ​​a conductive surface of the substrate, and a top electrode deposited on top of the sensitive layer; The surface morphology of the sensitive layer is TiO2 nanosheets with nanometer thickness, and the top electrode is a dense film formed by Au nanoparticles.

10. Use of the titanium dioxide-based memristive gas sensor according to claim 9 in detecting triethylamine at room temperature.

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