Controllable preparation method of nitrogen oxide gas-sensitive sensing material constructed by asymmetric sites

Abstract

The invention discloses a controllable preparation method of a nitrogen oxide gas-sensitive sensing material constructed by asymmetric sites. The preparation of a nitrogen-doped indium oxide NOx gas-sensitive sensing material constructed by O-In-N asymmetric sites is realized by adding urea in a calcining process. According to the invention, the preparation of the nitrogen-doped indium oxide NOx gas-sensitive sensing material with asymmetric site construction is realized. The material has excellent nitrogen dioxide sensing performance. The nitrogen-doped indium oxide NOx gas-sensitive sensing material constructed by asymmetric sites shows unique value in the field of semiconductor manufacturing and in the aspect of high-performance catalyst preparation.

Description

Technical Field

[0001] The present invention belongs to the field of NO x gas-sensing technology, and particularly relates to a controllable preparation method of a nitrogen-doped indium oxide gas-sensing material with asymmetric sites constructed thereon. Background Art

[0002] Indium oxide (In2O3) is a wide-bandgap n-type semiconductor material with high conductivity, high transparency, and excellent optoelectronic properties, and is widely used in multiple fields. In the field of gas sensing, indium oxide is widely used for detecting reducing gases (such as carbon monoxide, hydrogen, and methane) and oxidizing gases (such as nitrogen dioxide and ozone) due to its high sensitivity and fast response characteristics to various gases;. In the field of gas sensing, the advantages of indium oxide include high sensitivity, low detection limit, fast response and recovery times, and good thermal stability. However, indium oxide gas sensors also face challenges such as poor selectivity, insufficient long-term stability, and high energy consumption due to high operating temperatures.

[0003] Asymmetric sites refer to special active centers with asymmetric structural or electronic distributions on the material surface, usually caused by factors such as surface doping, adsorbed atoms, vacancies, ligand modification, high-index crystal planes, and phase reconstruction. This asymmetry can endow the material with unique catalytic properties, showing higher activity, selectivity, and stability in chemical reactions. For example, in the heterogeneous carbon dioxide hydrogenation reaction, asymmetric sites such as step sites, alloy structures, interfaces, and vacancies promote the activation of carbon dioxide molecules by perturbing the electronic structure of carbon dioxide molecules and polarizing adsorbed species, as well as the existence of local distortion tension. Asymmetric sites have broad application prospects in the fields of energy conversion and storage, environmental protection, and chemical production. By designing materials with specific asymmetric structures, the adsorption process of specific gases can be enhanced, and selectivity and sensitivity can be improved.

[0004] A nitrogen-doped indium oxide gas sensor with asymmetric sites constructed thereon is a gas sensor that constructs O-In-N asymmetric sites by introducing a nitrogen source during the calcination process in an oxygen-free atmosphere. Due to the construction of O-In-N asymmetric sites in this sensor, the charge density at the In site is significantly increased, enhancing the adsorption of target gas molecules, thereby increasing the selectivity for target gases and reducing the operating temperature. In addition, nitrogen-doped indium oxide gas sensors also have advantages such as high sensitivity and good stability

[0005] Therefore, designing and synthesizing a nitrogen-doped indium oxide NO x gas-sensing material with asymmetric sites constructed thereon provides a new choice for gas sensor materials and has important significance. Summary of the Invention

[0006] The object of the present invention is to provide a method for controllably preparing a nitrogen-doped indium oxide NO gas sensing material with asymmetric site construction. Based on the reaction and calcination processes, a nitrogen-doped indium oxide gas sensing material is prepared. The nitrogen-doped indium oxide gas sensing material exhibits excellent gas sensing performance for nitrogen oxides such as nitrogen dioxide (NO2) and nitric oxide (NO). x A method for controllably preparing a nitrogen oxide gas sensing material with asymmetric site construction prepares an N-In2O3 composite material through a hydrothermal reaction and a calcination process, combines it with a MEMS device, and obtains a MEMS gas sensor suitable for nitrogen dioxide detection. The specific steps are as follows:

[0007] The present invention is achieved through the following technical solutions:

[0008] A method for controllably preparing a nitrogen oxide gas sensing material with asymmetric site construction prepares an N-In2O3 composite material through a hydrothermal reaction and a calcination process, combines it with a MEMS device, and obtains a MEMS gas sensor suitable for nitrogen dioxide detection. The specific steps are as follows:

[0009] Step 1: Dissolve 180 mg of indium nitrate and 60 mg of terephthalic acid in 20 mL of N,N-dimethylformamide to form a white transparent solution. Then ultrasonically treat the white transparent solution for at least 1 hour.

[0010] Step 2: Seal the ultrasonically treated solution in an autoclave and react at 100 °C for 6 hours. After cooling to room temperature, centrifuge the sample, dry it at 80 °C and then grind it. Place the sample and urea in a muffle furnace at a mass ratio of 1:20, heat it at a rate of 1 °C / minute to 700 °C in a nitrogen atmosphere and calcine for 4 hours. After cooling to room temperature, nitrogen-doped indium oxide nanorods are obtained.

[0011] Step 3: Take 20 mg of the nitrogen-doped indium oxide material, mix it with 5 mL of ethanol, and disperse it for 5 minutes.

[0012] Step 4: Take 10 μL of the dispersed solution, drop-coat it onto a MEMS chip, and wait for it to air-dry naturally. After air-drying, a MEMS gas sensor of the nitrogen-doped indium oxide material is obtained.

[0013] Further, in step 2, the calcination temperature of the muffle furnace is 600 °C and 800 °C.

[0014] Further, in step 2, replace urea with potassium dihydrogen phosphate or selenium powder.

[0015] Further, in step 2, the calcination duration is 2 hours.

[0016] Further, in step 2, the mass ratio of nitrogen-doped indium oxide to urea is 1:5, 1:10, 1:15, 1:25.

[0017] Further, in step 4, by changing the substrate, this method can be applied to the preparation of various sensors, including ceramic tube sensors, flat panel sensors, MEMS sensors, surface acoustic wave sensors, and cantilever beam sensors.

[0018] Technical principle: The present invention provides a controllable preparation method for a nitrogen-doped indium oxide gas-sensing material with asymmetric site construction. The principle is that by adding urea with a mass ratio of 1:2 to indium oxide during the calcination process and calcining in a nitrogen atmosphere, a nitrogen-doped indium oxide gas sensor with O-In-N asymmetric site construction is obtained. The present invention prepares a nitrogen-doped indium oxide gas-sensing material with asymmetric site construction through a hydrothermal reaction and a calcination process, having process advantages such as a short preparation process, high uniformity, and good coverage. Indium oxide shows the best adsorption effect on nitrogen dioxide at 90 °C, and the sensitivity to nitric oxide is almost the same. After nitriding treatment to construct O-In-N asymmetric sites, it only shows a rapid response to nitrogen dioxide, and the working temperature is reduced to 60 °C.

[0019] The present invention has the following beneficial effects:

[0020] (1) The preparation of a nitrogen-doped indium oxide NO gas-sensing material with O-In-N asymmetric site construction is realized. x gas-sensing material preparation.

[0021] (2) The sensitivity of the gas-sensing material to nitrogen dioxide is significantly improved, and the selectivity and working temperature are also optimized.

[0022] (3) The nitrogen-doped indium oxide NO gas-sensing material with O-In-N asymmetric site construction x shows unique value in the field of semiconductor manufacturing and the preparation of high-performance catalysts. Description of the Drawings

[0023] Figure 1 is a synthesis schematic diagram of a nitrogen-doped indium oxide NO gas-sensing material with O-In-N asymmetric site construction. x gas-sensing material synthesis schematic diagram.

[0024] Figure 2 is an application schematic diagram of a nitrogen-doped indium oxide NO gas-sensing material with asymmetric site construction in the field of low-temperature gas sensing. x gas-sensing material application schematic diagram in low-temperature gas sensing field.

[0025] Figure 3 is an application schematic diagram of a nitrogen-doped indium oxide NO gas-sensing material with asymmetric site construction in the field of room-temperature gas sensing. x gas-sensing material application schematic diagram in room-temperature gas sensing field. Detailed Embodiments

[0026] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings: These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0027] Example 1

[0028] This embodiment provides a preparation method of a nitrogen-doped indium oxide NO gas-sensitive sensing material with asymmetric site construction, which specifically includes the following steps: x The preparation method of the gas-sensitive sensing material specifically includes the following steps:

[0029] Step 1. Dissolve 180 mg of indium nitrate and 60 mg of terephthalic acid in 20 mL of N,N-dimethylformamide to form a white transparent solution. Then ultrasonicate the white transparent solution for at least 1 hour;

[0030] Step 2: Seal the ultrasonicated solution in an autoclave and react at 100 °C for 6 hours. After cooling to room temperature, centrifuge the sample, dry it at 80 °C and then grind it. Place the sample and urea in a muffle furnace according to a mass ratio of 1:20, and heat it at a rate of 1 °C / min to calcine in a nitrogen atmosphere at 700 °C for 4 hours. After cooling to room temperature, nitrogen-doped indium oxide nanorods are obtained;

[0031] Example 2

[0032] This embodiment provides a preparation method of a phosphorus-doped indium oxide NO gas-sensitive sensing material with asymmetric site construction, which specifically includes the following steps: x The preparation method of the gas-sensitive sensing material specifically includes the following steps:

[0033] Step 1. Dissolve 180 mg of indium nitrate and 60 mg of terephthalic acid in 20 mL of N,N-dimethylformamide to form a white transparent solution. Then ultrasonicate the white transparent solution for at least 1 hour;

[0034] Step 2: Seal the ultrasonicated solution in an autoclave and react at 100 °C for 6 hours. After cooling to room temperature, centrifuge the sample, dry it at 80 °C and then grind it. Place the sample and sodium dihydrogen phosphate in a muffle furnace according to a mass ratio of 1:20, and heat it at a rate of 1 °C / min to calcine in a nitrogen atmosphere at 700 °C for 4 hours. After cooling to room temperature, nitrogen-doped indium oxide nanorods are obtained;

[0035] Example 3

[0036] This embodiment provides a preparation method of a selenium-doped indium oxide NO gas-sensitive sensing material with asymmetric site construction, which specifically includes the following steps: x The preparation method of the gas-sensitive sensing material specifically includes the following steps:

[0037] Step 1. Dissolve 180 mg of indium nitrate and 60 mg of terephthalic acid in 20 mL of N,N-dimethylformamide to form a white transparent solution. Then ultrasonicate the white transparent solution for at least 1 hour;

[0038] Step 2: Seal the ultrasonically treated solution in an autoclave and react at 100 °C for 6 hours. After cooling to room temperature, centrifuge the sample, dry it at 80 °C and then grind it. Place the sample and selenium powder in a muffle furnace at a mass ratio of 1:20, and heat it at a rate of 1 °C / min to 700 °C and calcine it in a nitrogen atmosphere for 4 hours. After cooling to room temperature, nitrogen-doped indium oxide nanorods are obtained;

[0039] As Figure 1 shown are the TEM images of indium oxide with anion doping having asymmetric sites prepared in the above Examples 1, 2, and 3, indicating that the construction of asymmetric sites can be achieved by adding an anion source during the calcination process.

[0040] As Figure 2 shown are the gas-sensing tests of indium oxide with anion doping having asymmetric sites prepared in the above Examples 1, 2, and 3. The material has a rapid response to nitrogen dioxide, a low detection limit, and good stability and repeatability.

[0041] As Figure 3 shown are the room-temperature gas-sensing tests of indium oxide with anion doping having asymmetric sites prepared in the above Examples 1, 2, and 3. The material has a rapid response to nitrogen dioxide at room temperature and good stability and repeatability.

[0042] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A controllable preparation method of a nitrogen oxide gas-sensing material with an asymmetric site structure, characterized in that, The N-In2O3 composite material was prepared by adding urea during the calcination process, and it was combined with a MEMS device to obtain a MEMS gas sensor suitable for nitrogen dioxide detection. The specific steps are as follows: Step 1: Dissolve 180 mg of indium nitrate and 60 mg of terephthalic acid in 20 mL of N,N-dimethylformamide to form a white transparent solution, and then ultrasonicate the white transparent solution for at least 1 hour; Step 2: Seal the ultrasonically treated solution in an autoclave and react at 100 °C for 6 hours. After cooling to room temperature, centrifuge the sample, dry it at 80 °C and then grind it. Place the sample and urea in a muffle furnace at a mass ratio of 1:20, heat it at a rate of 1 °C / min to 700 °C and calcine it in a nitrogen atmosphere for 4 hours. After cooling to room temperature, nitrogen-doped indium oxide nanorods are obtained; Step 3: Take 20 mg of the nitrogen-doped indium oxide material and mix it with 5 mL of ethanol, and disperse it for 5 minutes; Step 4: Take 10 μL of the dispersed solution and drop-coat it onto the MEMS chip, and wait for it to air-dry naturally. After air-drying, a MEMS gas sensor of the nitrogen-doped indium oxide material is obtained.

2. The controllable preparation method of the nitrogen oxide gas-sensing material with asymmetric sites constructed according to claim 1, characterized in that, In step 2, the calcination temperature of the muffle furnace is 600 °C and 800 °C.

3. The controllable preparation method of the nitrogen oxide gas-sensitive sensing material constructed with asymmetric sites according to claim 1, characterized in that, In step 2, replace urea with potassium dihydrogen phosphate or selenium powder.

4. The controllable preparation method of the nitrogen oxide gas-sensing material with asymmetric sites constructed according to claim 1, characterized in that, In step 2, the calcination duration is 2 hours.

5. The controllable preparation method of a nitrogen oxide gas-sensing material with asymmetric sites constructed according to claim 1, characterized in that, In step 2, the mass ratio of nitrogen-doped indium oxide to urea is 1:5, 1:10, 1:15, 1:

25.

6. The controllable preparation method of the nitrogen oxide gas-sensitive sensing material constructed with asymmetric sites according to claim 1, characterized in that, By changing the substrate, this method can be applied to the preparation of various sensors, including but not limited to ceramic tube sensors, flat panel sensors, MEMS sensors, surface acoustic wave sensors, and cantilever beam sensors.

Images