A method for in-situ growth of Ti3C2Tx-titanium dioxide heterostructure and its application

Abstract

This invention discloses a method and application for in-situ growth of Ti3C2Tx-titanium dioxide heterostructure material, belonging to the field of two-dimensional composite materials and gas sensor technology. The invention uses a hydrochloric acid solution containing fluorine compounds as the etching solvent and employs a hydrothermal method to etch Ti3AlC2 to prepare Ti3C2Tx material (Tx = -F, -OH, and -O). The Ti3C2Tx material is then subjected to oxygen microwave plasma treatment at low power, while controlling the oxygen volume fraction to 10-30%. This partially oxidizes the Ti3C2Tx material into two-dimensional sheet-like TiO2 oxides. These two-dimensional sheet-like TiO2 oxides tightly coat the surface of Ti3C2Tx, forming a Ti3C2Tx-TiO2 heterostructure material. Gas sensors prepared using this Ti3C2Tx-TiO2 heterostructure material exhibit excellent responsiveness and selectivity to hydrogen.

Description

Technical Field

[0001] This invention belongs to the field of two-dimensional composite materials and gas sensor technology, and particularly relates to a method and application of in-situ growth of Ti3C2Tx-titanium dioxide heterostructure material. Background Technology

[0002] As a clean, environmentally friendly, renewable, and abundant energy source, hydrogen has emerged as one of the most promising candidates for next-generation energy. However, hydrogen is highly explosive and flammable, requiring extreme caution during its preparation, storage, transportation, and application to prevent leaks. Therefore, developing highly sensitive and selective hydrogen sensors with rapid detection and recovery capabilities is crucial for detecting and mitigating potential hazards associated with hydrogen storage, transportation, and leaks. Metal-oxide-semiconductor (MOS) gas sensors are a widely used type of sensor, offering advantages such as low cost, small size, ease of integration, and real-time monitoring. However, the application of these sensors in wearable sensing devices is limited by several issues, such as high operating temperatures, long response times, poor selectivity, and broad spectral response to gases with similar redox properties.

[0003] Mxene is a novel two-dimensional transition metal carbide or nitride with a graphene-like two-dimensional layered structure. It possesses a large specific surface area and excellent electrical conductivity, stability, magnetic properties, and mechanical properties, making it widely applicable in catalysis, energy storage, and adsorption. Its general chemical formula is M. n+1 X n T x Where M is a transition metal element, X is carbon or nitrogen element, and T is... x The surface of MXene contains functional groups such as -F, -OH, and -O, with n = 1, 2, and 3. MXene is typically prepared by selectively etching away the a atom from the MAX phase using a chemical liquid-phase method. The surface of MXene contains numerous functional groups, providing abundant active sites for gas adsorption and surface reactions, and enabling specific interactions with particular gas molecules, thus achieving selective adsorption. However, its relatively low response value limits its application in hydrogen sensing.

[0004] Using metal oxide and MXene composite materials to fabricate gas sensors can improve the gas-sensing performance of MXene. The main reason for the improved performance is the combination of two different materials to form a heterojunction. Therefore, when the sensor captures the analyte gas molecules, a depletion layer and a hole accumulation layer that can regulate electron transport are formed. Currently, there have been some studies on the use of two-dimensional material MXene composite metal oxide semiconductor materials in the field of room temperature gas sensors. In situ growth of the corresponding oxide by partial oxidation of MXene is a simple method to construct metal oxide and MXene composite materials. For example, Peng et al. [Hybrids of Two-Dimensional Ti3C2 and TiO2 Exposing {001}Facets toward Enhanced Photocatalytic Activity, ACS Appl. Mater. Interfaces 2016, 8, 6051-6060] used Ti3C2T... x A simple hydrothermal reaction was used to partially oxidize and grow TiO2 nanosheets in situ to synthesize layered Ti3C2T. x Although TiO2 nanosheets were successfully grown, a hybrid composition consisting of Ti3C2T... x The layered structure also collapsed. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a method and application for in-situ growth of Ti3C2Tx-titanium dioxide heterostructure interface materials.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] One of the technical solutions of the present invention:

[0008] A method for in-situ growth of Ti3C2Tx-titanium dioxide heterostructure material (Ti3C2Tx-TiO2 heterostructure material) involves using a hydrochloric acid solution containing fluorine compounds as an etching solvent and preparing Ti3C2Tx material by hydrothermal etching of Ti3AlC2, wherein x = -F, -OH and -O;

[0009] The Ti3C2Tx material was subjected to oxygen microwave plasma treatment to obtain the Ti3C2Tx-TiO2 heterostructure material;

[0010] When performing oxygen microwave plasma treatment, the microwave power is 500-800W;

[0011] The oxygen microwave plasma treatment is carried out in an atmosphere in which an oxygen-argon mixture is introduced, wherein the volume fraction of oxygen in the oxygen-argon mixture is 10-30%.

[0012] This invention uses Ti3AlC2 as a MAX precursor to synthesize Ti3C2Tx material (x = -F, -OH, or -O) via a hydrothermal method. The Ti3C2Tx material is then subjected to low-power (500-800W) oxygen microwave plasma treatment, causing partial oxidation into two-dimensional sheet-like TiO2 oxides. These sheet-like TiO2 oxides tightly coat the Ti3C2Tx surface, forming a Ti3C2Tx-TiO2 heterostructure. Gas sensors fabricated using this Ti3C2Tx-TiO2 heterostructure exhibit excellent responsiveness to hydrogen. During the oxygen microwave plasma treatment, controlling the microwave power and oxygen volume fraction allows for slow oxidation of Ti3C2Tx, which is more conducive to the formation of its sheet-like structure.

[0013] The principle of this invention is as follows: Oxygen microwave plasma is used as the activation energy source to provide an oxygen-rich environment for the material. Under the bombardment of the oxygen microwave plasma, the oxygen in the plasma competes with the -F functional groups on the Ti3C2Tx surface, gradually replacing them. The released fluorine atoms adsorb onto the initially oxidized TiO2 surface, inhibiting the crystal growth of TiO2 along the (001) direction, thereby generating TiO2 nanosheets. Ultimately, Ti3C2Tx with a heterojunction surface is generated. x -TiO2 composite materials. The two-dimensional sheet-like structure has a higher specific surface area due to its thin planar structure, which is conducive to the adsorption of gas molecules and provides more active sites for surface reactions, thereby improving gas sensing performance. The construction of heterojunctions will cause band bending, promote electron-hole carrier separation, provide more carriers for gas sensing reactions, and thus improve the gas sensing performance of the material.

[0014] Preferably, in the method for in-situ growth of Ti3C2Tx-TiO2 heterostructure material, the microwave power during oxygen microwave plasma treatment is 500-700W, more preferably 700W.

[0015] Preferably, in the method for in-situ growth of Ti3C2Tx-TiO2 heterointerface material, the concentration of hydrochloric acid in the hydrochloric acid solution containing the fluorine compound is 4-12 mol / L, and the concentration of the fluorine compound is 1-2 mol / L. Appropriate concentrations of hydrochloric acid and the fluorine compound are sufficient to completely etch the Al in the precursor Ti3AlC2, thereby obtaining a two-dimensional accordion-shaped Ti3C2Tx.

[0016] The fluorine-containing compound is one of LiF, NH4F, and NaF.

[0017] Preferably, in the method for in-situ growth of Ti3C2Tx-TiO2 heterostructure interface material, the hydrothermal method is performed at a temperature of 120-180℃ for 1-5 days.

[0018] Preferably, in the method for in-situ growth of Ti3C2Tx-TiO2 heterostructure material, the oxygen microwave plasma treatment time is 10-60 min. If the oxygen microwave plasma treatment time is too short, the layered TiO2 formation will be incomplete; if the treatment time is too long, the accordion-like structure of Ti3C2Tx will collapse due to excessive oxidation. Both of these factors are detrimental to the adsorption of gas molecules, resulting in a lack of significant improvement in the material's gas-sensing performance.

[0019] Preferably, in the method for in-situ growth of Ti3C2Tx-TiO2 heterointerface material, the pressure during oxygen microwave plasma treatment is 100-1000 Pa, more preferably 500-1000 Pa. The intensity of the microwave plasma is related to the pressure; a suitable pressure range is used to control the intensity of the oxygen microwave plasma, thereby controlling the degree of oxidation of Ti3C2Tx.

[0020] The second technical solution of the present invention:

[0021] The present invention also provides a Ti3C2Tx-TiO2 heterostructure material obtained by in-situ growth according to the above method.

[0022] The third technical solution of the present invention:

[0023] The present invention also provides the application of the Ti3C2Tx-TiO2 heterointerface material in the preparation of a gas sensor, wherein the gas sensor is a hydrogen sensor.

[0024] The hydrogen sensor prepared in this invention uses Ti3C2T x / TiO2 heterostructure material is a sensitive material. The two-dimensional sheet structure has a higher specific surface area due to its thin planar structure, which is conducive to the adsorption of hydrogen molecules and provides more active sites for surface reactions, thereby improving the gas sensing performance.

[0025] The fourth technical solution of the present invention:

[0026] The present invention also provides a method for preparing a hydrogen sensor, wherein the above-mentioned Ti3C2Tx-TiO2 heterointerface material is mixed with alcohol, ground and deposited on a substrate containing electrodes (the alcohol will evaporate during the grinding process), and dried to obtain the hydrogen sensor.

[0027] Preferably, in the method for fabricating a hydrogen sensor, the substrate comprises one of aluminum oxide (Al2O3), zirconium oxide (ZrO2), polyimide (PI), and polyethylene terephthalate (PET). Al2O3 has high electrical resistance and thermal stability, and Ti3C2Tx-TiO2 heterojunction materials are easily grown on it; ZrO2 is also a material with good insulating properties and can be used as a sensor substrate; PI has good thermal stability, excellent transparency, and excellent insulation, while also possessing good dimensional stability, flexibility, and solvent resistance; PET, as a polymer plastic, has the characteristics of low cost, light weight, transparency, and good flexibility. Flexible PFT can reduce the influence of thermal effects on the deformation and electrical instability of the plastic substrate, and hydrogen sensors fabricated on flexible substrates (such as PI and PET) can adapt to special environments. In summary, using the above materials as substrates can, to a certain extent, affect the structure and mechanical properties of the hydrogen sensor, thereby improving the overall performance of the hydrogen sensor.

[0028] Preferably, in the method for preparing a hydrogen sensor, the deposition process includes screen printing, spraying, spin coating, or drop coating.

[0029] Preferably, in the method for preparing a hydrogen sensor, the drying temperature is 50-100°C and the drying time is 6-12 hours.

[0030] Compared with the prior art, the present invention has the following advantages and technical effects:

[0031] (1) This invention proposes a novel method for preparing Ti3C2Tx-TiO2 heterostructure materials. Low-power oxygen microwave plasma is used as the activation energy source to provide an oxygen-rich environment for the material. Under the bombardment of the oxygen microwave plasma, the two-dimensional Ti3C2Tx material is partially oxidized into corresponding TiO2 nanosheets, forming a Ti3C2Tx-TiO2 heterostructure material. x During oxygen plasma treatment, the oxygen in the plasma reacts with Ti3C2T. x The -F functional groups on the surface compete with each other and gradually replace them. The F atoms that are released will adsorb on the surface of the anatase TiO2 particles that are initially oxidized, inhibiting the crystal growth of TiO2 along the (001) direction, thereby generating two-dimensional TiO2 nanosheets.

[0032] (2) The Ti3C2Tx-TiO2 heterostructure material prepared by the method of this invention has a unique structure. Morphologically, the TiO2 generated by the partial oxidation of Ti3C2Tx is in the form of two-dimensional nanosheets, with TiO2 tightly wrapped around the surface of Ti3C2Tx. The two-dimensional sheet structure has a higher specific surface area due to its thin planar structure, which is conducive to the adsorption of gas molecules and provides more active sites for surface reactions, thereby improving the gas-sensing performance.

[0033] (3) The low-power oxygen microwave plasma treatment method used in this invention is simple and consumes little energy. The resulting Ti3C2Tx-TiO2 heterostructure material has high stability and a high response value and fast response recovery time to H2 in a wide concentration range. Attached Figure Description

[0034] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0035] Figure 1 The image shows the morphology of Ti3C2Tx prepared by the hydrothermal method in Example 1.

[0036] Figure 2 The image shows the morphology of the Ti3C2Tx / TiO2 heterostructure material prepared after oxygen microwave plasma treatment of Ti3C2Tx in Example 1.

[0037] Figure 3 The image shows the morphology of the Ti3C2Tx-TiO2 heterostructure material in Comparative Example 1.

[0038] Figure 4 The image shows the morphology of the Ti3C2Tx-TiO2 heterostructure material in Comparative Example 2.

[0039] Figure 5 The image shows the morphology of the Ti3C2Tx / TiO2 heterostructure material in Comparative Example 3.

[0040] Figure 6 The response recovery curve of the hydrogen sensor prepared by the Ti3C2Tx-TiO2 heterointerface material in Example 1 to 1000ppm hydrogen.

[0041] Figure 7 The sensor prepared from the Ti3C2Tx-TiO2 heterointerface material in Example 1 responds to 1000ppm H2, C2H6O, SO2, CH4, CO, and CO2. Detailed Implementation

[0042] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0043] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0044] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0045] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0046] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0047] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0048] All raw materials used in the embodiments of this invention were obtained through commercial purchase.

[0049] It should be noted that all aspects not described in detail in this invention are conventional operating methods in the field and are not the focus of this invention. For example, specific methods such as screen printing, spraying, spin coating, or drip coating are all completed using conventional methods.

[0050] The technical solution of the present invention will be further illustrated by the following embodiments.

[0051] Example 1

[0052] The MAX precursor Ti3AlC2 was added to 80 mL of a mixed solution of 4 mol / L hydrochloric acid and 1 mol / L LiF. After stirring evenly, the solution was transferred to a 100 mL stainless steel reactor lined with polytetrafluoroethylene. The reactor was hydrothermally reacted at 120 °C for 5 days. After cooling, the solution was centrifuged, washed, and dried to obtain Ti3C2Tx (x = -F, -OH, -O) powder. The obtained Ti3C2Tx powder was placed in a microwave plasma device, and an oxygen-argon mixture with an oxygen content of 20% (i.e., the volume fraction of oxygen in the oxygen-argon mixture was 20%) was introduced. The pressure was controlled at 500 Pa, the power was turned on and the power was controlled at 700 W. After oxygen plasma treatment for 40 min, the solution was removed to obtain the Ti3C2Tx-TiO2 heterointerface material.

[0053] Ti3C2Tx-TiO2 heterostructure material was mixed with alcohol, ground, and then screen-printed onto an alumina substrate containing electrodes. After drying at 80°C for 6 hours, a hydrogen sensor with Ti3C2Tx-TiO2 heterostructure material as the sensing material was obtained.

[0054] Example 2

[0055] The MAX precursor Ti3AlC2 was added to 80 mL of a mixed solution of 6 mol / L hydrochloric acid and 1.5 mol / L LiF. After stirring evenly, the solution was transferred to a 100 mL stainless steel reactor lined with polytetrafluoroethylene. The reactor was hydrothermally reacted at 140 °C for 3 days. After cooling, the solution was centrifuged, washed, and dried to obtain Ti3C2Tx (x = -F, -OH, -O) powder. The obtained Ti3C2Tx powder was placed in a microwave plasma device, and an oxygen-argon mixture with an oxygen content of 20% was introduced. The pressure was controlled at 1000 Pa, and the power was turned on and controlled at 700 W. After oxygen plasma treatment for 40 min, the solution was removed to obtain the Ti3C2Tx-TiO2 heterointerface material.

[0056] Ti3C2Tx-TiO2 heterostructure material was mixed with alcohol, ground, and then screen-printed onto an alumina substrate containing electrodes. After drying at 100°C for 6 hours, a hydrogen sensor with Ti3C2Tx-TiO2 heterostructure material as the sensing material was obtained.

[0057] Example 3

[0058] The MAX precursor Ti3AlC2 was added to 80 mL of a mixed solution of 8 mol / L hydrochloric acid and 1 mol / L LiF. After stirring evenly, the solution was transferred to a 100 mL stainless steel reactor lined with polytetrafluoroethylene. The reactor was hydrothermally reacted at 120 °C for 4 days. After cooling, the solution was centrifuged, washed, and dried to obtain Ti3C2Tx (x = -F, -OH, -O) powder. The obtained Ti3C2Tx powder was placed in a microwave plasma device with a power of 500 W and an oxygen-argon mixture of 10% oxygen. The pressure was controlled at 500 Pa. After oxygen plasma treatment for 40 min, the solution was removed to obtain the Ti3C2Tx-TiO2 heterointerface material.

[0059] Ti3C2Tx-TiO2 heterostructure material was mixed with alcohol, ground, and then deposited onto a zirconium oxide substrate containing electrodes by drop coating. After drying at 80°C for 6 hours, a hydrogen sensor with Ti3C2Tx-TiO2 heterostructure material as the sensing material was obtained.

[0060] Example 4

[0061] The MAX precursor Ti3AlC2 was added to 80 mL of a mixed solution of 4 mol / L hydrochloric acid and 1 mol / L LiF. After stirring evenly, the solution was transferred to a 100 mL stainless steel reactor lined with polytetrafluoroethylene. The reactor was hydrothermally reacted at 120 °C for 5 days. After cooling, the solution was centrifuged, washed, and dried to obtain Ti3C2Tx (x = -F, -OH, -O) powder. The obtained Ti3C2Tx powder was placed in a microwave plasma device, and an oxygen-argon mixture with an oxygen content of 30% was introduced. The pressure was controlled at 500 Pa, and the power was turned on and controlled at 800 W. After oxygen plasma treatment for 40 min, the solution was removed to obtain the Ti3C2Tx-TiO2 heterointerface material.

[0062] Ti3C2Tx-TiO2 heterostructure material was mixed with alcohol, ground, and then spin-coated onto a PI substrate containing electrodes. After drying at 50°C for 12 hours, a hydrogen sensor with Ti3C2Tx-TiO2 heterostructure material as the sensing material was obtained.

[0063] Example 5

[0064] The MAX precursor Ti3AlC2 was added to 80 mL of a mixed solution of 12 mol / L hydrochloric acid and 2 mol / L LiF. After stirring thoroughly, the mixture was transferred to a 100 mL stainless steel reactor lined with polytetrafluoroethylene. The reactor was hydrothermally reacted at 180 °C for one day. After cooling, the mixture was centrifuged, washed, and dried to obtain Ti3C2Tx. X=-F, -OH, -O) powder; the obtained Ti3C2Tx powder was placed in a microwave plasma device, and an oxygen-argon mixture with an oxygen content of 10% was introduced. The pressure was controlled at 100Pa, the power was turned on and the power was controlled at 700W. After oxygen plasma treatment for 60 minutes, it was taken out to obtain Ti3C2Tx-TiO2 heterostructure material.

[0065] Ti3C2Tx-TiO2 heterostructure material was mixed with alcohol, ground, and then sprayed onto a PET substrate containing electrodes. After drying at 100°C for 6 hours, a hydrogen sensor with Ti3C2Tx-TiO2 heterostructure material as the sensing material was obtained.

[0066] Comparative Example 1

[0067] The difference between this comparative example and Example 1 is that Ti3C2Tx is not subjected to oxygen microwave plasma treatment, but is instead placed in a conventional tube furnace and heated for 40 minutes in an oxygen-argon mixed atmosphere with an oxygen content of 20%. The specific method is as follows:

[0068] The MAX precursor Ti3AlC2 was added to 80 mL of 4 mol / L hydrochloric acid and 1 mol / L LiF solution. After stirring thoroughly, the mixture was transferred to a 100 mL stainless steel reactor lined with polytetrafluoroethylene and hydrothermally reacted at 120 °C for 5 days. After cooling, the mixture was centrifuged, washed, and dried to obtain Ti3C2T. x Powder. The obtained Ti3C2T x The powder was placed in a tube furnace, and an oxygen-argon mixture with an oxygen content of 20% was introduced. The pressure was controlled at 500 Pa, and the mixture was kept at this temperature for 40 min to obtain the Ti3C2Tx / TiO2 composite material.

[0069] The Ti3C2Tx / TiO2 composite material was mixed with alcohol, ground, and then screen-printed onto an alumina substrate containing electrodes. After drying at 80°C for 6 hours, the sensor was obtained.

[0070] Comparative Example 2

[0071] The difference between this comparative example and Example 1 is that the gas introduced during oxygen microwave plasma treatment is 100% pure oxygen. The specific method is as follows:

[0072] The MAX precursor Ti3AlC2 was added to 80 mL of 3 mol / L hydrochloric acid and 0.05 mol / L LiF solution. After stirring thoroughly, the mixture was transferred to a 100 mL stainless steel reactor lined with polytetrafluoroethylene. The reactor was hydrothermally reacted at 120 °C for 5 days. After cooling, the mixture was centrifuged, washed, and dried to obtain Ti3C2T. x Powder; the obtained Ti3C2T xThe powder was placed in a microwave plasma device, 100% pure oxygen was introduced, the pressure was controlled at 500 Pa, the power was turned on and the power was controlled at 700 W, and the oxygen microwave plasma treatment was carried out for 40 min to obtain the Ti3C2Tx / TiO2 composite material.

[0073] The Ti3C2Tx / TiO2 composite material was mixed with alcohol, ground, and then screen-printed onto an alumina substrate containing electrodes. After drying at 80°C for 6 hours, the sensor was obtained.

[0074] Comparative Example 3

[0075] The difference between this comparative example and Example 1 is that the microwave power used in this example is high power (2000W) when performing oxygen microwave plasma. The specific method is as follows:

[0076] The MAX precursor Ti3AlC2 was added to 80 mL of a mixed solution of 4 mol / L hydrochloric acid and 1 mol / L LiF. After stirring evenly, the solution was transferred to a 100 mL stainless steel reactor lined with polytetrafluoroethylene. The reactor was hydrothermally reacted at 120 °C for 5 days. After cooling, the solution was centrifuged, washed, and dried to obtain Ti3C2Tx (x = -F, -OH, -O) powder. The obtained Ti3C2Tx powder was placed in a microwave plasma device, and an oxygen-argon mixture with an oxygen content of 20% (i.e., the volume fraction of oxygen in the oxygen-argon mixture was 20%) was introduced. The pressure was controlled at 500 Pa, the power was turned on and the power was controlled at 2000 W. After oxygen plasma treatment for 40 min, the solution was removed to obtain the Ti3C2Tx-TiO2 heterointerface material.

[0077] Ti3C2Tx-TiO2 heterostructure material was mixed with alcohol, ground, and then screen-printed onto an alumina substrate containing electrodes. After drying at 80°C for 6 hours, a hydrogen sensor with Ti3C2Tx-TiO2 heterostructure material as the sensing material was obtained.

[0078] I. SEM Morphology Analysis

[0079] Figure 1 The image shows the morphology of Ti3C2Tx prepared by the hydrothermal method in Example 1. It can be seen that Ti3C2Tx prepared by the hydrothermal method has a two-dimensional accordion-like structure.

[0080] Figure 2 The image shows the morphology of the Ti3C2Tx-TiO2 heterostructure material prepared after oxygen microwave plasma treatment of Ti3C2Tx in Example 1. It can be seen that Ti3C2Tx... x During oxygen plasma treatment, the oxygen in the plasma reacts with Ti3C2T. xCompetition among the -F functional groups on the surface leads to their gradual replacement. The released F atoms adsorb onto the surface of the initially oxidized anatase TiO2 particles, inhibiting the crystal growth of TiO2 along the (001) direction. This results in the formation of numerous two-dimensional sheet-like TiO2 particles that tightly encapsulate the Ti3C2Tx surface. The two-dimensional sheet-like structure, due to its thin planar structure, possesses a higher specific surface area, which facilitates the adsorption of gas molecules and provides more active sites for surface reactions, thereby improving gas-sensing performance.

[0081] Figure 3 The image shows the morphology of the Ti3C2Tx / TiO2 heterostructure material in Comparative Example 1. It can be seen that under conventional heating methods, Ti3C2Tx only generates some TiO2 particles on the surface, resulting in a low specific surface area. This is not conducive to the adsorption of gas molecules and cannot provide more active sites for surface reactions, leading to a decrease in gas-sensing performance.

[0082] Figure 4 The image shows the morphology of the Ti3C2Tx / TiO2 heterostructure material in Comparative Example 2. When the oxygen ratio is too high, Ti3C2Tx will be over-oxidized, resulting in a low specific surface area, which is not conducive to the adsorption of gas molecules and cannot provide more active sites for surface reactions, leading to a decrease in gas-sensing performance.

[0083] Figure 5 The image shows the morphology of the Ti3C2Tx / TiO2 heterostructure material in Comparative Example 3. When the microwave power is too high, Ti3C2Tx will be over-oxidized, resulting in a low specific surface area, which is not conducive to the adsorption of gas molecules and cannot provide more active sites for surface reactions, leading to a decrease in gas-sensing performance.

[0084] II. Gas Sensing Performance Test

[0085] The hydrogen sensor prepared by this invention was tested according to methods disclosed in the art, and the tests were conducted in a gas-sensitive testing device (KLUM-QM-104). The specific steps are as follows: (1) Connect the sensor to the gas-sensitive testing device, introduce air into the device until it stabilizes, and record the resistance value R of the device in the air. a (2) Pass H2 into the device until the resistance value stabilizes again, and record the resistance value R of the device in H2. g (3) Re-introduce air into the device until the resistance stabilizes, at which point the device completes one response recovery process. The response value is defined as: Response = R a / R g Different H2 concentrations were obtained by gas dilution method, with test concentrations ranging from 0 to 10,000 ppm.

[0086] Figure 6 The Ti3C2T in Example 1 xThe response recovery curve of the sensor prepared from TiO2 heterointerface material to 1000ppm hydrogen gas shows that Ti3C2T obtained after oxygen microwave plasma treatment... x -TiO2 heterostructure materials exhibit a high response value and a fast response recovery time to hydrogen.

[0087] Table 1 shows the response values ​​and response recovery times of the sensors prepared in Examples 1-5 and Comparative Examples 1-3 to 1000 ppm H2.

[0088] Table 1

[0089] Response value (Ra / Rg) Response / Recovery Time (s) Example 1 22.5 10 / 45 Example 2 20.3 15 / 58 Example 3 21.2 12 / 49 Example 4 19.9 19 / 62 Example 5 20.8 18 / 60 Comparative Example 1 8.4 49 / 75 Comparative Example 2 12.4 35 / 66 Comparative Example 3 9.1 46 / 83

[0090] Note: In Table 1, R a R is the resistance value of the gas sensor in air (ohms: Ω). g The resistance value of the gas sensor in H2 (ohms: Ω).

[0091] Table 1 shows that Ti3C2T after oxygen plasma treatment x The TiO2 obtained by partial oxidation has a two-dimensional nanosheet morphology and is tightly wrapped around Ti3C2T. x When the surface is oxidized, the gas-sensing response to H2 is best enhanced. In Comparative Examples 1 and 2, the partially oxidized TiO2 is not a two-dimensional nanosheet and does not have a higher specific surface area, which is not conducive to the adsorption of gas molecules and cannot provide more active sites for surface reactions, thus resulting in a decrease in gas-sensing performance.

[0092] Figure 7 The Ti3C2T in Example 1 x The response values ​​of the sensor prepared from TiO2 heterointerface material to 1000ppm H2, 1000ppm C2H6O, 1000ppm SO2, 1000ppm CH4, 1000ppm CO, and 1000ppm CO2 indicate that the Ti3C2T obtained after oxygen microwave plasma treatment... x / TiO2 heterostructure materials exhibit high selectivity for hydrogen.

[0093] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. Use of a Ti3C2Tx-titania heterointerface material in the preparation of a gas sensor, characterized in that, The gas sensor is a hydrogen sensor; The Ti3C2Tx-titanium dioxide heterojunction material is prepared by an in-situ growth method, and a hydrofluoric acid solution containing a fluorine compound is used as an etching solvent to etch Ti3AlC2 to prepare Ti3C2Tx material, wherein x=-F, -OH and -O; The Ti3C2Tx material is subjected to oxygen microwave plasma treatment to obtain the Ti3C2Tx-titanium dioxide heterojunction material; During the oxygen microwave plasma treatment, the microwave power is 500-700 W, the treatment time is 10-60 min, and the pressure is 500-1000 Pa; The oxygen microwave plasma treatment is carried out in an atmosphere of oxygen-argon mixed gas, and the volume fraction of oxygen in the oxygen-argon mixed gas is 10-30%; The concentration of hydrochloric acid in the hydrofluoric acid solution is 4-12 mol / L, and the concentration of the fluorine compound is 1-2 mol / L.

2. Use according to claim 1, characterized in that, The fluorine compound is one of LiF, NH4F and NaF.

3. Use according to claim 1, characterized in that, The temperature of the hydrothermal method is 120-180 ℃, and the time is 1-5 days.

4. A method for producing a hydrogen sensor, characterized by, The hydrogen sensor is the hydrogen sensor in claim 1, the Ti3C2Tx-titanium dioxide heterojunction material in claim 1 is mixed with alcohol, ground and then deposited on a substrate containing an electrode, dried to obtain the hydrogen sensor.

5. The method of claim 4, wherein the hydrogen sensor is prepared by a method comprising: The substrate comprises one of aluminum oxide, zirconium oxide, polyimide and polyethylene terephthalate.

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