GaN-Ni3 (HITP) 2 / PANI trimethylamine sensor and preparation method thereof

Abstract

The invention discloses a GaN-Ni3 (HITP) 2 / PANI trimethylamine sensor and a preparation method thereof, and belongs to the technical field of gas sensors. The sensor comprises a GaN epitaxial wafer, electrodes are deposited on two sides of the surface of the GaN epitaxial wafer, Ni3 (HITP) 2 is compounded in the middle of the GaN epitaxial wafer through a solution self-assembly method, and a PANI film is compounded on the surface of the GaN epitaxial wafer compounded with the Ni3 (HITP) 2; according to the method, the GaN material is etched and compounded with PANI and Ni3 (HITP) 2, the sensitive characteristic to TMA is improved by fully utilizing the synergistic effect of different materials, and high-performance detection of ppb-level TMA at the room temperature is achieved; compared with a traditional TMA detection mode, the prepared GaN-Ni3 (HITP) 2 / PANI trimethylamine sensor has the advantages of being high in detection sensitivity, high in response and recovery speed, capable of achieving room-temperature detection and the like; the problems of poor stability, weak recovery performance and low sensitivity of a trimethylamine sensor at room temperature are solved.

Description

Technical Field

[0001] This invention belongs to the field of gas sensor technology, specifically a GaN-Ni3(HITP)2 / PANI trimethylamine sensor and its preparation method. Background Technology

[0002] Trimethylamine (TMA) is a pungent organic amine that is a colorless gas at room temperature, posing a threat to human health and environmental safety. Inhalation of TMA irritates the eyes and respiratory tract, causing symptoms such as coughing, difficulty breathing, dizziness, and nausea. Long-term exposure to TMA may damage vital organs such as the liver and kidneys. Furthermore, TMA metabolism is closely related to health problems such as cardiovascular disease (CVD) and chronic kidney disease (CKD). Exhaled TMA can serve as a potential biomarker for detecting kidney disease. In addition, TMA poses a serious threat to environmental safety. Due to its flammability, TMA can cause violent combustion or even explosion in high-temperature or open-flame environments, releasing harmful fumes. In conclusion, the identification of TMA is of great significance for assessing human health and environmental safety.

[0003] Gas sensors are devices that detect the concentration of gases in the environment and convert them into corresponding electrical signals. For the sake of human health and safety, the development of high-performance trimethylamine sensors is of great significance.

[0004] There are many types of traditional trimethylamine gas sensors. Among them, semiconductor metal oxide-based gas sensors have been widely studied due to their high sensitivity, small size and low cost. However, their practical feasibility is limited by their high operating temperature, high energy consumption and poor selectivity.

[0005] Gallium nitride (GaN) semiconductor material is a third-generation strategic advanced electronic material with excellent properties such as high electron mobility, carrier concentration, thermal stability, and chemical stability. It also shows great promise in the field of gas sensors for trace detection of various gases. In recent years, many researchers have focused on developing novel GaN gas sensors for the detection of gases such as NO2 and H2, leveraging GaN's good stability and high process compatibility. However, GaN suffers from low sensitivity to trace amounts of oxygen (TMA).

[0006] In comparison, semiconductor metal-organic framework polymer trimethylamine (PANI) sensors exhibit better selectivity for TMA and can achieve detection at both low and room temperatures. Semiconductor metal-organic framework polymer materials possess excellent chemical and environmental stability, low raw material costs, simple and convenient synthesis and doping processes, controllable conductivity, and unique doping methods, making them a highly promising TMA-sensitive material widely used in TMA detection. However, using single PANI material as a gas-sensitive material suffers from poor long-term stability, weak recovery performance, and low sensitivity, limiting its further application.

[0007] In summary, for the current field of trimethylamine sensors, there is a need to develop highly stable, highly sensitive, and low-cost room-temperature trimethylamine sensors to ensure the safety of industrial production and human health monitoring. Summary of the Invention

[0008] This invention overcomes the shortcomings of the prior art by proposing a GaN-Ni3(HITP)2 / PANI trimethylamine sensor and its preparation method, which solves the problems of poor stability, weak recovery performance and low sensitivity of trimethylamine sensors at room temperature.

[0009] This invention is achieved through the following technical solution: A GaN-Ni3(HITP)2 / PANI trimethylamine sensor includes a GaN epitaxial wafer, electrodes deposited on both sides of the GaN epitaxial wafer surface, Ni3(HITP)2 composited in the middle of the GaN epitaxial wafer by solution self-assembly, and a PANI thin film composited on the surface of the GaN epitaxial wafer with Ni3(HITP)2 composited.

[0010] Preferably, the GaN epitaxial wafer has undergone chemical vapor deposition and wet etching.

[0011] Preferably, the chemical vapor deposition is performed during the growth of the GaN epitaxial wafer by doping with one of the elements silicon, magnesium, aluminum, or indium.

[0012] Preferably, the silicon concentration of the GaN layer in the GaN epitaxial wafer is 1×10⁻⁶. 18 ~10×10 18 cm -3 The concentration of magnesium doping is 1×10 18 ~5×10 18 cm -3 The doped aluminum or indium is 1 to 30 wt% of the mass of Ga element.

[0013] Preferably, the GaN epitaxial wafer is grown using sapphire, silicon, or silicon carbide as a substrate.

[0014] Preferably, Ti / Au electrodes are deposited on both sides of the GaN epitaxial wafer surface.

[0015] Preferably, the thickness of the deposited Ti / Au electrode is 50–100 nm.

[0016] The method for preparing a GaN-Ni3(HITP)2 / PANI trimethylamine sensor includes the following steps: S1. A GaN epitaxial wafer doped with one of the elements silicon, magnesium, aluminum or indium is grown on a substrate using chemical vapor deposition. S2. Etching is performed using a wet etching process to obtain an etched GaN epitaxial wafer; S3. Use magnetron sputtering or vapor deposition techniques to deposit Ti / Au electrodes at both ends of the etched GaN epitaxial wafer, and composite Ni3(HITP)2 in the middle part of the GaN epitaxial wafer using a solution self-assembly method. S4. The GaN epitaxial wafer with composite Ni3(HITP)2 is immersed in a dilute HCl solution of aniline, and ammonium persulfate solution is added dropwise. A PANI film is composited on the surface of the GaN epitaxial wafer by in-situ oxidative polymerization to prepare the GaN-Ni3(HITP)2 / PANI composite sensitive material.

[0017] Preferably, the wet etching process involves placing the GaN epitaxial wafer in a molten alkaline etchant environment at 240–330°C and etching continuously for 10–30 minutes.

[0018] Preferably, the alkaline etchant used in the alkaline etchant environment is one of KOH, NaOH, and LiOH.

[0019] In the preparation method of the present invention, the concentration of the ammonium persulfate solution used for in-situ oxidative polymerization to form a PANI film is preferably 0.01 to 0.03 mol / L.

[0020] More preferably, after adding the ammonium persulfate solution, the reaction solution is allowed to stand for 20 to 30 minutes to laminate a PANI film onto the GaN epitaxial wafer surface.

[0021] The present invention preferably involves cleaning the prepared GaN-Ni3(HITP)2 / PANI composite sensing material with a 1-3 mol / L dilute HCl solution, followed by drying at 80°C to obtain the GaN-Ni3(HITP)2 / PANI trimethylamine sensor.

[0022] The GaN-Ni3(HITP)2 / PANI trimethylamine sensor prepared by this invention can be used as a TMA gas concentration detection sensor and applied to TMA concentration detection in various occasions.

[0023] The gas-sensing characteristics of the GaN-Ni3(HITP)2 / PANI sensor prepared in this invention were detected using the CGS-MT intelligent gas-sensing analysis system.

[0024] The beneficial effects of this invention compared to the prior art are as follows: 1. This invention improves the sensitivity to TMA by etching GaN material and combining it with PANI and Ni3(HITP)2, fully utilizing the synergistic effect between different materials. This enables high-performance detection of ppb-level TMA at room temperature. Compared with traditional TMA detection methods, the GaN-Ni3(HITP)2 / PANI trimethylamine sensor prepared by this invention has many advantages, such as high detection sensitivity, fast response and recovery speed, and the ability to achieve room temperature detection. Furthermore, the trimethylamine sensor is simple to prepare and inexpensive.

[0025] 2. This invention prepares a GaN-Ni3(HITP)2 / PANI trimethylamine sensor by self-assembling an in-situ solution of Ni3(HITP)2, which has abundant active sites and a large specific surface area, onto an etched GaN epitaxial wafer, and then polymerizing a PANI sensitive film using an in-situ oxidative polymerization method. The etched GaN and PANI form a surface np heterostructure, generating a Schottky barrier between GaN and Ni3(HITP)2, which promotes electron mobility and greatly improves the detection sensitivity of TMA. It also has a fast response and recovery speed, enabling the detection of TMA at the ppb level and exhibiting good long-term stability.

[0026] 3. The GaN-Ni3(HITP)2 / PANI trimethylamine sensor of the present invention can not only realize rapid and stable monitoring of TMA in many putrefactive environments, but also has important significance for the monitoring and prevention of early liver and kidney diseases in humans. Attached Figure Description

[0027] Figure 1 This is a SEM image of the GaN-Ni3(HITP)2 / PANI composite gas-sensitive material prepared in Example 1.

[0028] Figure 2 This is the response recovery curve of the GaN-Ni3(HITP)2 / PANI trimethylamine sensor prepared in Example 1 to TMA.

[0029] Figure 3 The graph shows the response recovery curve of the Ni3(HITP)2 / PANI trimethylamine sensor prepared in Comparative Example 1 to TMA.

[0030] Figure 4 This is the response recovery curve of the PANI trimethylamine sensor prepared in Comparative Example 2 to TMA.

[0031] Figure 5 This is the response recovery curve of the GaN-PANI trimethylamine sensor prepared in Comparative Example 3 to TMA. Detailed Implementation

[0032] To make the technical problems to be solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail with reference to the embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The technical solutions of this invention are described in detail below with reference to the embodiments and accompanying drawings, but the scope of protection is not limited thereto. Example 1

[0033] This embodiment proposes a method for preparing a GaN-Ni3(HITP)2 / PANI trimethylamine sensor, including the following steps: S1: The silicon doped with a concentration of 5 × 10⁻⁶ elements will be prepared by chemical vapor deposition (MOCVD). 18 cm -3 The GaN epitaxial wafer was cut into 3×5mm sizes.

[0034] S2: Place a certain amount of KOH in a quartz boat, melt it at 330°C on a heating platform, place a GaN epitaxial wafer in the boat, and use KOH to melt and etch the GaN epitaxial wafer for 50 minutes.

[0035] S3: Using magnetron sputtering, a 100nm thick Ti / Au electrode is deposited on both ends of the etched GaN epitaxial wafer through a mask to prepare a sensor thin film.

[0036] S4: The GaN epitaxial wafer was placed in a mixed solution consisting of 20 ml HATP·6HCl (0.2 mmol) deionized water, 20 ml NiCl2·6H2O (0.6 mmol) deionized water, and 0.075 ml ammonia (0.1 mmol, NH4OH). The solution was stirred continuously at 27°C for 2 hours. Ni3(HITP)2 was self-assembled in situ in the middle part of the GaN epitaxial wafer to obtain GaN-Ni3(HITP)2.

[0037] S5: Add 0.1141g of ammonium persulfate powder to 50mL of deionized water and stir to obtain an ammonium persulfate solution with a concentration of 0.01mol / L; take 8.3mL of concentrated HCl and dilute it to 50mL with deionized water to obtain a dilute HCl solution with a concentration of 2mol / L; take 15mL of the above solution and add it dropwise to 15mL of deionized water to obtain a dilute HCl solution with a concentration of 1mol / L.

[0038] S6: Place the GaN epitaxial wafer of Ni3(HITP)2 self-assembled in situ into a centrifuge tube containing 0.05 mL of aniline solution, add 10 mL of 2 mol / L dilute HCl solution to form a protic acid environment, and then quickly add 5 mL of 0.01 mol / L ammonium persulfate solution. Let it stand for 30 min to prepare the GaN-Ni3(HITP)2 / PANI composite sensitive material.

[0039] S7: Take out the GaN-Ni3(HITP)2 / PANI composite sensing material, wash it with 1mol / L dilute HCl solution, and dry it at 60℃ on a heating table to obtain the GaN-Ni3(HITP)2 / PANI trimethylamine sensor.

[0040] The gas-sensing performance of the GaN-Ni3(HITP)2 / PANI trimethylamine sensor prepared in this embodiment to TMA was tested using the CGS-MT intelligent gas-sensing analysis system at (27±2)℃ and a relative humidity of 30%.

[0041] The strength of a sensor's ability to detect TMA is represented by the magnitude of its response.

[0042] Response formula: Response(%)=(Rg-Ra) / Ra×100%. Where Ra represents the baseline resistance value of the sensor in air before TMA injection, and Rg represents the real-time resistance value of the sensor after TMA injection.

[0043] The response of the GaN-Ni3(HITP)2 / PANI trimethylamine sensor to different concentrations of TMA is as follows: Figure 2 As shown, the sensor has a fast response and recovery speed to TMA, with a detection limit of 500 ppb. The inset shows the response of the GaN-Ni3(HITP)2 / PANI trimethylamine sensor to TMA concentrations of 200 ppm, 100 ppm, 50 ppm, 10 ppm, 5 ppm, 1 ppm and 500 ppb.

[0044] Comparative Example 1 S1: Mix 20 ml of HATP·6HCl (0.2 mmol) deionized water, 20 ml of NiCl2·6H2O (0.6 mmol) deionized water, and 0.075 ml of ammonia (0.1 mmol, NH4OH), and then stir continuously at 27°C for 2 hours to obtain Ni3(HITP)2.

[0045] S2: The Ni3(HITP)2 sensitive material solution was repeatedly washed with anhydrous ethanol-based deionized water and centrifuged 3 times. Then, it was dried in a vacuum drying oven at 80°C for 12 hours to prepare Ni3(HITP)2 powder.

[0046] S3: Add 0.1141g of ammonium persulfate powder to 50mL of deionized water and stir to obtain an ammonium persulfate solution with a concentration of 0.01mol / L; take 8.3mL of concentrated HCl and dilute it to 50mL with deionized water to obtain a dilute HCl solution with a concentration of 2mol / L; take 15mL of the above solution and add it dropwise to 15mL of deionized water to obtain a dilute HCl solution with a concentration of 1mol / L.

[0047] S4: The in-situ self-assembled Ni3(HITP)2 powder was placed into a centrifuge tube containing 0.05 mL of aniline solution. 10 mL of 2 mol / L dilute HCl solution was added to form a protic acid environment, and 5 mL of 0.01 mol / L ammonium persulfate solution was quickly added. After standing for 30 min, Ni3(HITP)2 / PANI composite sensitive material was prepared.

[0048] The gas-sensing performance of the pure Ni3(HITP)2 / PANI trimethylamine sensor prepared in this embodiment to TMA was tested using the CGS-MT intelligent gas-sensing analysis system at (27±2)℃ and a relative humidity of 30%.

[0049] The response of the pure Ni3(HITP)2 / PANI trimethylamine sensor to different concentrations of TMA is as follows: Figure 3 As shown, the sensor's response to 200 ppm TMA is 8.5%, and its detection limit is 10 ppm, indicating that its detection performance is poor.

[0050] Comparative Example 2 S1: Add 0.1141g of ammonium persulfate powder to 50mL of deionized water and stir to obtain an ammonium persulfate solution with a concentration of 0.01mol / L; take 8.3mL of concentrated HCl and dilute it to 50mL with deionized water to obtain a dilute HCl solution with a concentration of 2mol / L; take 15mL of the above solution and add it dropwise to 15mL of deionized water to obtain a dilute HCl solution with a concentration of 1mol / L.

[0051] S2: Add 0.05 mL of aniline solution to a centrifuge tube, add 10 mL of 2 mol / L dilute HCl solution to form a protic acid environment, and quickly add 5 mL of 0.01 mol / L ammonium persulfate solution. Let stand for 30 min to prepare PANI sensitive material.

[0052] S3: The PANI sensitive material solution was repeatedly washed with anhydrous ethanol-based deionized water and centrifuged 3 times. Then, it was dried in a vacuum drying oven at 80°C for 12 hours to prepare PANI powder.

[0053] S4: Disperse PANI powder at a concentration of 5 mg / mL in deionized water, grind it, and then coat it onto Ag interdigitated electrode sheets to prepare a pure PANI trimethylamine sensor.

[0054] The gas-sensing performance of the pure PANI trimethylamine sensor prepared in this embodiment to TMA was tested using the CGS-MT intelligent gas-sensing analysis system under conditions of (27±2)℃ and a relative humidity of 30% RH. According to... Figure 4 The given response curves of the pure PANI trimethylamine sensor to different concentrations of TMA show that it has low sensitivity to TMA and weak recovery performance.

[0055] Comparative Example 3 S1: The silicon doped with a concentration of 5 × 10⁻⁶ elements will be prepared by chemical vapor deposition (MOCVD). 18 cm -3 The GaN epitaxial wafer was cut into 3×5mm sizes.

[0056] S2: Place a certain amount of KOH in a quartz boat, melt it at 330°C on a heating platform, place a GaN epitaxial wafer in the boat, and use KOH to melt and etch the GaN epitaxial wafer for 50 minutes.

[0057] S3: Using magnetron sputtering or evaporation technology, deposit Ti / Au electrodes with a thickness of 100 nm on both ends of the etched GaN epitaxial wafer through a mask to prepare a sensor thin film.

[0058] S4: Add 0.1141g of ammonium persulfate powder to 50mL of deionized water and stir to obtain an ammonium persulfate solution with a concentration of 0.01mol / L; take 8.3mL of concentrated HCl and dilute it to 50mL with deionized water to obtain a dilute HCl solution with a concentration of 2mol / L; take 15mL of the above solution and add it dropwise to 15mL of deionized water to obtain a dilute HCl solution with a concentration of 1mol / L.

[0059] S5: Place the GaN epitaxial wafer into a centrifuge tube containing 0.05 mL of aniline solution, add 10 mL of 2 mol / L dilute HCl solution to form a protic acid environment, and then quickly add 5 mL of 0.01 mol / L ammonium persulfate solution. Let it stand for 30 min to prepare the GaN / PANI composite sensitive material.

[0060] S6: Take out the GaN / PANI composite sensing material, wash it with 1 mol / L dilute HCl solution, and dry it at 60°C on a heating stage to obtain the GaN / PANI trimethylamine sensor.

[0061] The gas-sensing performance of the GaN / PANI trimethylamine sensor prepared in this embodiment to TMA was tested using the CGS-MT intelligent gas-sensing analysis system at (27±2)℃ and a relative humidity of 30%.

[0062] The performance test results of the GaN / PANI trimethylamine sensor on TMA are as follows: Figure 5 As shown, the sensor's sensitivity to TMA is improved to a certain extent, but it still has a slow response recovery speed and a high detection limit.

[0063] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0064] The detailed descriptions listed above are merely specific descriptions of feasible implementation methods of this application and are not intended to limit the scope of protection of this application. All equivalent implementation methods or modifications made without departing from the spirit of the art of this application should be included within the scope of protection of this invention.

Claims

1. A GaN-Ni3(HITP)2 / PANI trimethylamine sensor, characterized in that, The product includes a GaN epitaxial wafer, electrodes deposited on both sides of the GaN epitaxial wafer surface, Ni3(HITP)2 composited in the middle of the GaN epitaxial wafer by solution self-assembly, and a PANI thin film composited on the surface of the GaN epitaxial wafer with Ni3(HITP)2 composite.

2. The GaN-Ni3(HITP)2 / PANI trimethylamine sensor according to claim 1, characterized in that, The GaN epitaxial wafers were prepared by chemical vapor deposition and wet etching.

3. The GaN-Ni3(HITP)2 / PANI trimethylamine sensor according to claim 2, characterized in that, The chemical vapor deposition is a process in which silicon, magnesium, aluminum, or indium are doped during the growth of GaN epitaxial wafers.

4. The GaN-Ni3(HITP)2 / PANI trimethylamine sensor according to claim 3, characterized in that, The silicon concentration doped in the GaN layer of the GaN epitaxial wafer is 1×10⁻⁶. 18 ~10×10 18 cm -3 The concentration of magnesium doping is 1×10 18 ~5×10 18 cm -3 The doped aluminum or indium is 1 to 30 wt% of the mass of Ga element.

5. The GaN-Ni3(HITP)2 / PANI trimethylamine sensor according to claim 3, characterized in that, The GaN epitaxial wafer is grown using sapphire, silicon, or silicon carbide as a substrate.

6. The GaN-Ni3(HITP)2 / PANI trimethylamine sensor according to claim 1, characterized in that, Ti / Au electrodes are deposited on both sides of the GaN epitaxial wafer surface.

7. A GaN-Ni3(HITP)2 / PANI trimethylamine sensor according to claim 6, characterized in that, The thickness of the deposited Ti / Au electrode is 50–100 nm.

8. A method for preparing a GaN-Ni3(HITP)2 / PANI trimethylamine sensor according to any one of claims 1-7, characterized in that, Includes the following steps: S1. A GaN epitaxial wafer doped with one of the elements silicon, magnesium, aluminum or indium is grown on a substrate using chemical vapor deposition. S2. Etching is performed using a wet etching process to obtain an etched GaN epitaxial wafer; S3. Use magnetron sputtering or vapor deposition techniques to deposit Ti / Au electrodes at both ends of the etched GaN epitaxial wafer, and composite Ni3(HITP)2 in the middle part of the GaN epitaxial wafer using a solution self-assembly method. S4. The GaN epitaxial wafer with composite Ni3(HITP)2 is immersed in a dilute HCl solution of aniline, and ammonium persulfate solution is added dropwise. A PANI film is composited on the surface of the GaN epitaxial wafer by in-situ oxidative polymerization to prepare the GaN-Ni3(HITP)2 / PANI composite sensitive material.

9. The method for preparing a GaN-Ni3(HITP)2 / PANI trimethylamine sensor according to claim 8, characterized in that, The wet etching process involves placing the GaN epitaxial wafer in a molten alkaline etchant environment at 240–330°C and etching continuously for 10–30 minutes.

10. The method for preparing a GaN-Ni3(HITP)2 / PANI trimethylamine sensor according to claim 9, characterized in that, The alkaline etchant used in the alkaline etchant environment is one of KOH, NaOH, or LiOH.

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