Ammonia gas sensor of MXene and TiO2 composite material and preparation method thereof
By growing titanium dioxide particles on the surface of MXene to form a heterojunction composite material, the problems of high energy consumption and low sensitivity of existing gas sensors are solved, realizing low-cost, high-selectivity and fast-response ammonia detection.
Patent Information
- Application Number
- CN202310260641.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-03-17
- Publication Date
- 2026-02-03
- Estimated Expiration
- 2043-03-17
AI Technical Summary
Existing metal oxide gas sensors suffer from high operating temperature, high energy consumption, and low sensitivity when detecting ammonia. Two-dimensional semiconductor materials such as MXene exhibit weak signals, poor selectivity, and long response recovery times when used alone.
Titanium dioxide particles were grown on the surface of MXene using a hydrothermal method to form a heterojunction composite nanomaterial. Interdigitated electrode plates were then fabricated on an alumina substrate to construct an ammonia gas sensor based on the MXene-TiO2 composite material. The ammonia gas was detected by utilizing the resistance change of the semiconductor gas sensor.
It achieves high selectivity and high response value for low concentrations of ammonia at room temperature, and the material is simple to prepare, inexpensive, and suitable for miniaturization and integration with microelectronic devices.
Smart Images
Figure CN116359287B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electronic components technology, specifically relating to an ammonia gas sensor made of MXene and TiO2 composite materials and its preparation method. Background Technology
[0002] In recent years, with the increasing demands for a better living environment and growing attention to environmental issues, the detection of polluting and toxic gases requires higher standards. Ammonia, as one of the harmful gases to human health, is widely used in various fields of production and daily life, including nitrogen fertilizers and industrial refrigerants. It is one of the most harmful environmental pollutants generated during ordinary industrial production and manufacturing processes. According to standards issued by the U.S. Occupational Safety and Health Administration (OSHA), human exposure to ammonia at a concentration of 25 ppm should not exceed 8 hours, and the maximum exposure time at a concentration of 35 ppm is 15 minutes. Furthermore, ammonia is also a natural metabolic product of the human body. Detecting the ammonia content in human exhaled breath is of great significance for early disease diagnosis, as excessive ammonia in exhaled breath may be caused by liver and lung-related diseases. Therefore, finding high-performance NH3 sensors is of great importance for human health and safety.
[0003] Currently, among the various types of gas sensors, the research and fabrication technology of metal oxide-based gas sensors is the most mature, and they are widely used due to their reliable quality and low cost. The gas sensors widely available on the market are primarily metal oxide-based. Their advantages are obvious, such as high sensitivity, small size, and low manufacturing cost; however, their disadvantages are also significant, such as high operating temperature, high energy consumption during long-term operation, and relatively low sensitivity. With the development of two-dimensional semiconductor materials, their gas-sensing characteristics have also received widespread attention. The superior structure and electrical properties of two-dimensional semiconductor materials make them more suitable for the development requirements of sensor miniaturization, high sensitivity, low power consumption, and high reliability.
[0004] MXene is a graphene-like two-dimensional material composed of transition metal nitrides, carbides, or carbonitrides with a thickness of several atomic layers. A team led by Lee (Eunji Lee, Armin Vahid Mohammadi, Barton C. Prorok, Young Soo Yoon, Majid Beidaghi, and Dong-Joo Kim. Room Temperature Gas Sensing of Two-Dimensional Titanium Carbide (MXene), ACS Appl. Mater. Interfaces 2017, 9, 42, 37184–37190) pioneered the study of the gas-sensing properties of MXene, investigating the response of the sensor to various volatile gases, including methanol, ethanol, acetone, and ammonia, at room temperature. The results showed that MXene, as a gas-sensing material, responds to all of these gases. However, MXene also has inherent drawbacks as a gas-sensing material, such as low signal strength, poor selectivity, and long response / recovery times. Therefore, researchers modified the surface of MXene to achieve a better sensitization effect. Liu's research group (Zhi Liu, Tingting He, Haoyu Sun, Baoyu Huang, Xiaogan Li. Layered MXene heterostructured with In₂O₃ nanoparticles for ammonia sensors at room temperature, Sensors & Actuators: B. Chemical 365 (2022) 131918.) investigated the response of MXene to ammonia after being composited with In₂O₃. It can be seen that MXene composited with other metal oxides to obtain nanocomposite materials can overcome the defects of single components. Controlling the material morphology while constructing a heterojunction structure will improve the gas-sensing performance. Nanostructured titanium dioxide, as a traditional n-type semiconductor, has been widely studied for use in gas sensors. Its low cost and stable properties make it very suitable as a gas-sensing material. Therefore, the design and synthesis of gas-sensing materials composed of MXene and titanium dioxide will have significant scientific and practical implications. Summary of the Invention
[0005] The purpose of this invention is to provide an ammonia gas sensor and its detection method that uses a composite material of MXene and TiO2, exhibits good selectivity for low concentrations of ammonia, high response value, good long-term stability, and can operate at room temperature.
[0006] The technical solution of the present invention:
[0007] An ammonia gas sensor based on an MXene and TiO2 composite material includes a gas-sensitive material and an interdigitated electrode plate. The gas-sensitive material is uniformly coated on the surface of the interdigitated electrode plate with a coating thickness of 1 μm to 100 μm. The gas-sensitive material is composed of MXene and titanium dioxide composite nanomaterials.
[0008] The MXene and titanium dioxide composite nanomaterial is formed by growing granular titanium dioxide on the surface of accordion-shaped MXene using a hydrothermal method.
[0009] The interlayer spacing of the MXene is 500nm to 1µm, and the titanium dioxide size is 70nm.
[0010] The interdigitated electrode plate is an alumina substrate with pure gold electrodes on the front and 3 to 7 pairs of interdigitated fingers. The back of the interdigitated electrode plate is a heating resistance plate with a maximum heating temperature of 400°C.
[0011] The ammonia gas sensor operates at room temperature.
[0012] A fabrication process for an ammonia gas sensor made of MXene and TiO2 composite materials includes the following steps:
[0013] (1) Disperse MXene in ethanol and sonicate for 30 min, wherein the concentration of MXene is 0.0268-0.0626 mol / L. Then add a mixed solution of isopropyl titanate, ethanol and acetylacetone, wherein the volume ratio of isopropyl titanate, ethanol and acetylacetone is 1:1:0.1, and control the molar ratio of MXene to isopropyl titanate to be (2-5):10. After stirring for 30 min, add ethanol and water to the above mixed solution, wherein the volume ratio of ethanol to water is 10:1, and control the volume ratio of isopropyl titanate to water to be 41:100.
[0014] (2) The mixed solution obtained in step (1) was transferred to a hydrothermal reactor lined with polytetrafluoroethylene and heated to 220°C at a heating rate of 2°C / min for 6 hours. The product after hydrothermal reaction was collected and the reaction product was obtained by centrifugation. The obtained solid product was washed several times with deionized water and ethanol. The obtained solid product was placed in a drying oven and dried at 60°C for 12 hours to obtain MXene / TiO2 composite material.
[0015] (3) Transfer the MXene / TiO2 composite material to a mortar and grind it for 10 min until it becomes powder. Then, disperse the ground MXene / TiO2 composite material powder in deionized water and sonicate it for 1 min to form a dispersion of 6 mg / ml to 10 mg / ml. Then, take the dispersion and coat it onto the surface of the interdigitated electrode plate. After coating it evenly, place it in a drying oven at 60°C for 6 h and let it cool naturally to room temperature to obtain an ammonia gas sensor of MXene and TiO2 composite material.
[0016] In steps (1) and (3), the ultrasonic power is 240W to 260W.
[0017] Working Principle: The ammonia gas sensor based on the MXene and TiO2 composite material of this invention is a resistive semiconductor gas sensor. It mainly utilizes the change in resistance of the semiconductor when it comes into contact with a gas to detect the composition or concentration of the gas. When the device is placed in air, oxygen molecules pre-adsorbed on the surface of the gas-sensitive material will be ionized in the form of oxygen ions. At this time, the material is in a high-resistance state. When it comes into contact with the gas to be measured, the oxygen ions adsorbed on the surface react with the gas, and electrons return to the semiconductor gas-sensitive material, thus reducing the resistance.
[0018] The beneficial effects of this invention are:
[0019] (1) The present invention uses a hydrothermal method to obtain a novel heterojunction composite nanomaterial. The raw materials are readily available, inexpensive, and the preparation process is simple. It is a two-dimensional semiconductor preparation scheme with low equipment investment and simple process flow.
[0020] (2) The composite material of the present invention has uniformly distributed titanium dioxide particles on the surface, which form a heterojunction with MXene. This can guide electrons to accumulate on the surface material, enhance the gas-sensitive selectivity of the material, and the electron migration between MXene and titanium dioxide helps to promote additional oxygen adsorption on the material surface, thereby improving the gas-sensitive performance.
[0021] (3) The interdigitated electrode used in this invention can be made of alumina as a substrate. The MXene and TiO2 composite material is coated on the alumina substrate to make an ammonia gas sensor with advantages such as low power consumption, fast response time, compatibility with CMOS process, and easy integration with other microelectronic devices. Attached Figure Description
[0022] Figure 1 The image shows the scanning electron microscope (SEM) microstructure of the MXene and TiO2 composite material of this invention.
[0023] Figure 2 This is a comparison of the response of the gas sensor made of the MXene and TiO2 composite material and the pure MXene material of this invention to 30 ppm ammonia gas.
[0024] Figure 3 This is a comparison chart showing the response of the ammonia gas sensor made of MXene and TiO2 composite materials of the present invention to several common volatile interfering gases and ammonia gas. Detailed Implementation
[0025] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.
[0026] Example 1
[0027] A fabrication process for an ammonia gas sensor made of MXene and TiO2 composite materials includes the following steps:
[0028] (1) Disperse 45mg MXene in 10ml ethanol and sonicate for 30min. Then add a mixed solution of 0.41ml isopropyl titanate, 0.41ml ethanol and 0.041ml acetylacetone, stir for 30min and then add 10ml ethanol and 1ml water to the above mixed solution.
[0029] (2) The mixed solution obtained in step (1) was transferred to a hydrothermal reactor lined with polytetrafluoroethylene and heated to 220°C at a heating rate of 2°C / min for 6 hours. The product after the hydrothermal reaction was collected and the reaction product was obtained by centrifugation. The obtained solid product was washed several times with deionized water and ethanol. The obtained solid product was placed in a drying oven and dried at 60°C for 12 hours to obtain the composite material.
[0030] (3) Transfer the MXene / TiO2 composite material to a mortar and grind it for 10 min until it becomes powder. Then, disperse the ground MXene / TiO2 composite material powder in deionized water and sonicate it for 1 min to form a dispersion of 6 mg / ml to 10 mg / ml. Then, take the dispersion and coat it onto the surface of the interdigitated electrode plate. After coating it evenly, place it in a drying oven at 60°C for 6 h and let it cool naturally to room temperature to obtain the MXene / TiO2 composite gas sensor.
[0031] In steps (1) and (3), the ultrasonic power is 240W;
[0032] Example 2
[0033] A fabrication process for an ammonia gas sensor made of MXene and TiO2 composite materials includes the following steps:
[0034] (1) Disperse 70mg MXene in 10ml ethanol and sonicate for 30min. Then add a mixed solution of 0.41ml isopropyl titanate, 0.41ml ethanol and 0.041ml acetylacetone, stir for 30min and then add 10ml ethanol and 1ml water to the above mixed solution.
[0035] (2) The mixed solution obtained in step (1) was transferred to a hydrothermal reactor lined with polytetrafluoroethylene and heated to 220°C at a heating rate of 2°C / min for 6 hours. The product after the hydrothermal reaction was collected and the reaction product was obtained by centrifugation. The obtained solid product was washed several times with deionized water and ethanol. The obtained solid product was placed in a drying oven and dried at 60°C for 12 hours to obtain the composite material.
[0036] (3) Transfer the MXene / TiO2 composite material to a mortar and grind it for 10 min until it becomes powder. Then, disperse the ground MXene / TiO2 composite material powder in deionized water and sonicate it for 1 min to form a dispersion of 6 mg / ml to 10 mg / ml. Then, take the dispersion and coat it onto the surface of the interdigitated electrode plate. After coating it evenly, place it in a drying oven at 60°C for 6 h and let it cool naturally to room temperature to obtain the MXene / TiO2 composite gas sensor.
[0037] In steps (1) and (3), the ultrasonic power is 250W.
[0038] Example 3
[0039] A fabrication process for an ammonia gas sensor made of MXene and TiO2 composite materials includes the following steps:
[0040] (1) Disperse 105mg MXene in 10ml ethanol and sonicate for 30min. Then add a mixed solution of 0.41ml isopropyl titanate, 0.41ml ethanol and 0.041ml acetylacetone, stir for 30min and then add 10ml ethanol and 1ml water to the above mixed solution.
[0041] (2) The mixed solution obtained in step (1) was transferred to a hydrothermal reactor lined with polytetrafluoroethylene and heated to 220°C at a heating rate of 2°C / min for 6 hours. The product after the hydrothermal reaction was collected and the reaction product was obtained by centrifugation. The obtained solid product was washed several times with deionized water and ethanol. The obtained solid product was placed in a drying oven and dried at 60°C for 12 hours to obtain the composite material.
[0042] (3) Transfer the MXene / TiO2 composite material to a mortar and grind it for 10 min until it becomes powder. Then, disperse the ground MXene / TiO2 composite material powder in deionized water and sonicate it for 1 min to form a dispersion of 6 mg / ml to 10 mg / ml. Then, take the dispersion and coat it onto the surface of the interdigitated electrode plate. After coating it evenly, place it in a drying oven at 60°C for 6 h and let it cool naturally to room temperature to obtain the MXene / TiO2 composite gas sensor.
[0043] In steps (1) and (3), the ultrasonic power is 260W.
[0044] Example 4
[0045] Performance testing of ammonia gas sensor:
[0046] The MXene / TiO2 composite ammonia gas sensor prepared in step (3) of Example 2 was placed in an air atmosphere, and ammonia gas molecules were introduced at room temperature. The resistance change of the sensor in air and in a 30ppm ammonia atmosphere with air as the background was measured by a multimeter and used as the sensor signal.
[0047] Figure 2 A comparison graph of the response of the MXene / TiO2 composite material prepared in Example 2 and the gas sensor prepared from pure MXene material to 30 ppm ammonia gas is provided.
[0048] Figure 3 The response of the MXene / TiO2 composite ammonia gas sensor prepared in Example 2 to several common volatile interfering gases and ammonia gas is shown in the comparison graph.
[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A fabrication process for an ammonia gas sensor made of MXene and TiO2 composite materials, characterized in that, Includes the following steps: (1) Disperse MXene in ethanol and sonicate for 30 min, wherein the concentration of MXene is 0.0268-0.0626 mol / L. Then add a mixed solution of isopropyl titanate, ethanol and acetylacetone, wherein the volume ratio of isopropyl titanate, ethanol and acetylacetone is 1:1:0.1, and control the molar ratio of MXene to isopropyl titanate to be (2-5):
10. After stirring for 30 min, add ethanol and water to the above mixed solution, wherein the volume ratio of ethanol to water is 10:1, and control the volume ratio of isopropyl titanate to water to be 41:
100. The ultrasonic power is 240W~260W. (2) The mixed solution obtained in step (1) was transferred to a hydrothermal reactor lined with polytetrafluoroethylene and heated to 220°C at a heating rate of 2°C / min for 6 h of hydrothermal reaction. The product after hydrothermal reaction was collected and the reaction product was obtained by centrifugation. The obtained solid product was washed several times with deionized water and ethanol. The obtained solid product was placed in a drying oven and dried at 60°C for 12 h to obtain MXene / TiO2 composite material. (3) Transfer the MXene / TiO2 composite material to a mortar and grind it for 10 min until it becomes powder. Then disperse the ground MXene / TiO2 composite material powder in deionized water and sonicate it for 1 min to form a dispersion of 6 mg / ml to 10 mg / ml. Then take the dispersion and coat it onto the surface of the interdigitated electrode plate. After coating it evenly, place it in a drying oven at 60°C for 6 h and let it cool naturally to room temperature to obtain an ammonia gas sensor of MXene and TiO2 composite material. The ultrasonic power is 240 W to 260 W.
2. An ammonia gas sensor made of MXene and TiO2 composite material, prepared according to the fabrication process of the ammonia gas sensor of MXene and TiO2 composite material as described in claim 1, is characterized in that... The ammonia gas sensor includes a gas-sensitive material and an interdigitated electrode plate. The gas-sensitive material is uniformly coated on the surface of the interdigitated electrode plate with a coating thickness of 1 μm to 100 μm. The gas-sensitive material is composed of MXene and titanium dioxide composite nanomaterials. The MXene and titanium dioxide composite nanomaterials are formed by growing granular titanium dioxide on the surface of accordion-shaped MXene using a hydrothermal method. The interlayer spacing of the MXene is 500 nm to 1 μm, and the titanium dioxide size is 70 nm.
3. An ammonia gas sensor based on an MXene and TiO2 composite material according to claim 2, characterized in that, The interdigitated electrode plate is an alumina substrate with pure gold electrodes on the front and 3 to 7 pairs of interdigitated fingers. The back of the interdigitated electrode plate is a heating resistance plate with a maximum heating temperature of 400°C.
4. An ammonia gas sensor based on an MXene and TiO2 composite material according to claim 3, characterized in that, The ammonia gas sensor operates at room temperature.