Ag monatomic modified In2O3 single crystal film prepared based on pulse voltage discharge and method thereof, and gas sensitive sensor
By depositing Ag single atoms on the surface of In2O3 single crystal thin film using pulsed voltage discharge technology, the problem of unstable loading of noble metal single atoms was solved, and a high-performance NO2 gas sensor was prepared, realizing efficient and stable gas detection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INST OF WENZHOU ZHEJIANG UNIV
- Filing Date
- 2026-02-11
- Publication Date
- 2026-05-08
AI Technical Summary
Existing technologies struggle to efficiently and stably load noble metal single atoms onto the surface of In2O3 single-crystal thin films, resulting in insufficient performance of the sensing materials. Furthermore, the fabrication process is complex and costly, making it difficult to achieve real-time detection by high-performance NO2 gas sensors.
Ag single atoms were deposited on the surface of In2O3 single crystal thin film using pulsed voltage discharge technology. By controlling the high voltage pulse parameters, a high-density, directional Ag single atom beam was formed. Combined with magnetron sputtering and annealing, Ag single atom modified In2O3 single crystal thin film was prepared.
Efficient and stable Ag single-atom loading was achieved, improving the crystallinity and electrical properties of the thin film, and a highly sensitive and selective NO2 gas sensor was fabricated, suitable for real-time detection in fields such as environmental monitoring and industrial safety.
Smart Images
Figure CN121992487A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of gas sensing material preparation and semiconductor devices, specifically a method for preparing Ag single-atom modified In2O3 single-crystal thin films based on pulsed voltage discharge, and a gas sensor. Background Technology
[0002] NO2 is a major air pollutant, primarily originating from vehicle exhaust, industrial waste gas, and the combustion of fossil fuels. Long-term exposure to low concentrations of NO2 can severely harm the human respiratory system, while high concentrations can lead to environmental problems such as acid rain and photochemical smog. Therefore, developing high-performance gas sensors capable of rapidly, accurately, and in real-time detecting low concentrations of NO2 is urgently needed and of great significance in fields such as environmental monitoring, industrial safety, smart homes, and medical diagnostics.
[0003] Noble metal single-atom catalysts, with their extreme atomic utilization and unique electronic structure, offer a revolutionary approach to significantly improve the performance of sensing materials. Among them, In₂O₃ single-crystal thin films are ideal carrier materials, but efficiently, uniformly, and stably loading noble metal single atoms onto their surfaces faces key technological challenges. Current mainstream single-atom preparation and loading techniques, such as wet chemical methods, are prone to atomic aggregation, while atomic layer deposition (ALD) technology suffers from problems such as complex processes, high costs, and poor compatibility with thin film processes.
[0004] Based on this, the present invention proposes an Ag-modified In2O3 single crystal thin film and a gas sensor prepared by pulse voltage discharge technology, which can be effectively used in the field of NO2 detection. Summary of the Invention
[0005] This invention aims to provide a method for preparing Ag-modified In2O3 single-crystal thin films based on pulsed voltage discharge, as well as a gas sensor, to achieve efficient synthesis of sensitive materials with high atom utilization and stable structure, and ultimately obtain advanced NO2 gas sensor devices with high sensitivity and high selectivity, meeting the urgent needs of environmental monitoring, industrial safety and other fields for accurate and real-time gas detection technology.
[0006] This invention provides the following technical solution: A method for preparing Ag single-atom modified In₂O₃ single-crystal thin films based on pulsed voltage discharge technology includes the following steps: 1) The substrate is placed in the vacuum chamber of a magnetron sputtering equipment, and an In2O3 target is used as the In source. An indium oxide In2O3 single crystal thin film is grown on the substrate by magnetron sputtering. The substrate is yttrium oxide stabilized zirconium oxide (YSZ). 2) The indium oxide single crystal film obtained in step 1) is placed on a sample stage of a vacuum chamber equipped with a pulsed voltage discharge electrode and an Ag target. Ag particles are evaporated based on the pulsed voltage discharge process and deposited on the surface of the indium oxide single crystal film material to form dispersed clusters. After annealing, an Ag single atom modified In2O3 single crystal film is obtained.
[0007] Furthermore, in step 1), the substrate is sequentially cleaned with acetone, anhydrous ethanol, and deionized water before being placed in the vacuum chamber of the magnetron sputtering equipment.
[0008] Furthermore, in step 1), the magnetron sputtering process specifically includes: S1, evacuating the vacuum chamber and then heating the substrate to 400-600°C at a heating rate of 30°C / min; S2. Set the magnetron sputtering equipment to 80~100W, introduce argon gas, and pre-sputter the In2O3 target for 2~5 minutes to clean it. S3. Argon and oxygen are introduced into the vacuum chamber, and the argon-oxygen ratio in the vacuum chamber is adjusted to 10:1~5:1, the total pressure is 0.40~2.0Pa, the power is 80~100W, and the sputtering time is 10~30min.
[0009] Furthermore, in step 2), the Ag target is used as a discharge cathode or placed in front of the cathode, and the distance between the sample stage and the Ag target is 5-30 cm.
[0010] Furthermore, in step 2), the process of evaporating Ag particles based on pulsed voltage discharge technology and depositing them on the surface of indium oxide single crystal thin film material to form dispersed clusters specifically involves: first, evacuating the vacuum chamber to a background vacuum level not exceeding 1.0 × 10⁻⁶. -3 Next, argon gas is introduced as the working gas to maintain the chamber pressure at 0.1-10 Pa; then, a high-voltage pulse power supply is applied to the pulse voltage discharge electrode to evaporate Ag particles and deposit them on the surface of the indium oxide single crystal thin film material to form dispersed clusters.
[0011] Furthermore, the specific pulse parameters for applying the high-voltage pulse power supply to the pulse voltage discharge electrode are: pulse voltage 1-20 kV, pulse frequency 10-1000 Hz, and pulse width 1-300 mm. Under the influence of a high-intensity pulsed electric field, pulsed discharge occurs, generating high-energy electrons and argon ions. These ions bombard the surface of the Ag target. By controlling the pulse energy (pulse voltage, pulse frequency, and pulse width), the bombardment process is primarily a combination of thermal evaporation and micro-area sputtering. This rapidly heats and sublimates the Ag target surface, generating a high-density Ag atomic vapor cloud while suppressing the formation of large particle clusters. A continuously supplied argon gas flow passes through the Ag target surface area, mixing with the generated Ag atomic vapor. Utilizing the directional flow of Ar gas (controlled by pressure difference or carrier gas channel design), the Ag atomic vapor is carried out of the discharge region, forming a collimated or diffused atomic beam directed towards the In₂O₃ thin film substrate. This process, through the rapid transport of Ar gas and the low-temperature environment within the chamber, causes the Ag vapor to condense rapidly during its flight, forming a beam dominated by single atoms and extremely small clusters.
[0012] Furthermore, in step 2), the deposition time is 30 seconds to 30 minutes. After deposition, the sample is annealed under vacuum or protective atmosphere at room temperature to 400 °C to enhance the bonding between Ag atoms and the In2O3 substrate.
[0013] An Ag-modified In2O3 single-crystal thin film prepared based on pulsed voltage discharge technology is obtained by any of the methods described above; the single-crystal In2O3 thin film has a specific crystal orientation.
[0014] A gas-sensitive sensor for detecting low-concentration NO2 utilizes the Ag single-atom modified In2O3 single-crystal thin film material as the sensitive layer material.
[0015] Furthermore, the low concentration is less than 100 ppm.
[0016] Sensor fabrication and gas detection: An Al / Au interdigitated electrode was deposited on the surface of the resulting thin film using a thermal evaporation deposition method to construct a sensor. Gas-sensitive measurements were performed on the obtained samples using a CGS-MT intelligent gas-sensitive analysis system. A certain amount of NO2 or dry air was alternately introduced into the test chamber, and a DGL-V gas-liquid distribution system with automatic humidity control was used. In typical tests, humidity was dynamically controlled by a dual-flow dynamic humidity generator, DHD-Ⅱ. The response value was defined as the resistance R of the gas sensor against an air background. a With resistance R in the target gas NO2 environment g The ratio.
[0017] Compared with the prior art, the present invention has the following significant advantages: (1) The preparation method is efficient, controllable, and compatible: The pulsed voltage discharge technology used in this invention can efficiently generate high-density, directional Ag single-atom beams by adjusting the high-voltage pulse parameters. This method is a non-liquid-phase, in-situ dry process, which effectively avoids the common problems of atomic migration and aggregation in wet chemical methods, as well as the disadvantages of ALD technology such as precursor contamination, expensive equipment, and complex processes. The process conditions are mild and the steps are simple. It has good compatibility with existing semiconductor thin film preparation technologies (such as magnetron sputtering) and is easy to integrate and scale up.
[0018] (2) Clean and efficient process: The entire process is carried out in a vacuum or low-pressure inert atmosphere, with no solvents or liquid phase chemical residues, avoiding pollution. The pulse discharge has high instantaneous power, high atomic yield, and fast deposition rate.
[0019] (3) Unique effects of the substrate: The YSZ substrate, through its structural matching, high temperature stability and chemical inertness, promotes the formation of highly oriented films during magnetron sputtering epitaxial growth of In2O3 films, significantly improving the crystal quality, electrical properties and functional reliability of the films. (3) Significant performance improvement: The Ag / In2O3 thin film modified by this invention forms uniform Ag single-atom sites on its surface. The NO2 gas sensor constructed using this thin film material exhibits excellent comprehensive gas sensing performance, showing extremely strong resistance response to low concentrations (<100 ppm) of NO2 gas, with a response value (R0). a / R g The performance was significantly higher than that of unmodified or traditionally nanoparticle-modified In2O3 sensors. Attached Figure Description
[0020] Figure 1 XRD diffraction pattern of an Ag single-atom modified In2O3 thin film grown on a YSZ substrate according to an embodiment of the present invention; Figure 2 An embodiment of the present invention shows the Ag K-edge EXAFS spectrum of an Ag single-atom modified In2O3 thin film grown on a YSZ substrate. Figure 3 An embodiment of the present invention provides a repeatability curve of an Ag / In2O3-based sensor at its optimal operating temperature in a 50 ppm NO2 environment. Detailed Implementation
[0021] Example: Preparation of Ag single-atom modified In₂O₃ thin films for gas sensing Synthesis of sensitive layer material and fabrication of gas sensor: (1) A 10 mm*10 mm (111) oriented single crystal YSZ substrate was ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 20 min in sequence.
[0022] (2) Place the substrate in the vacuum chamber of the magnetron sputtering equipment, place the In2O3 target, set the power of the magnetron sputtering equipment to 100W, introduce argon gas, and pre-sputter the In2O3 target for 5 minutes to clean it.
[0023] (3) Then draw a vacuum to achieve 5*10 -4 At a vacuum level of Pa, the temperature is increased to 600 °C at a rate of 30 °C / min.
[0024] (4) The vacuum degree reaches 5*10 -4 After Pa, set the oxygen flow rate to 5 sccm and the argon flow rate to 50 sccm, then open the inlet valve.
[0025] (5) Control the vacuum degree of the thin film gauge to 2.0 Pa and observe whether the target surface glows. After glowing, modify the vacuum degree of the thin film gauge to 0.44 Pa.
[0026] (6) Set the RF power supply to 80 W, start the RF power supply, sputter for 20 min, apply electric and magnetic fields to generate argon ions, and bombard the target material with argon ions to cause In2O3 on the target material surface to detach from the target material and react with the oxygen introduced at the same time to obtain an indium oxide In2O3 single crystal thin film.
[0027] (7) Take out the In2O3 single crystal film and place it on the sample stage of another vacuum chamber. The chamber is equipped with a pulse discharge electrode and a high-purity Ag target. The distance between the sample stage and the Ag target is controlled at 15 cm.
[0028] (8) Evacuate the chamber to 5.0 × 10⁻⁶. -4 Pa, then high-purity argon gas is introduced as the working gas at a flow rate of 30 sccm to maintain a stable chamber pressure of 1.0 Pa.
[0029] (9) The pulse voltage is set to 8 kV, the pulse frequency is set to 200 Hz, and the pulse width is set to 200 Hz. s, producing a high-density cloud of Ag atoms in vapor.
[0030] (10) A continuous flow of high-purity Ar gas passes through the surface region of the Ag target and mixes with the generated Ag atom vapor. The deposition time is controlled at 5 minutes. After deposition, the sample is annealed in a protective atmosphere at room temperature for 2 hours to obtain a structurally stable Ag single-atom modified In2O3 single crystal film.
[0031] (11) Place a mask template of interdigitated electrodes on the material surface and deposit 20 nm Al / 20 nm Au on the material surface by thermal evaporation to prepare a sensor.
[0032] (12) Finally, heat the prepared sensor at 300 °C for 10 min to age the sensor.
[0033] Gas Sensitivity Test: The obtained samples were subjected to gas-sensitive measurements using an intelligent gas-sensitive analysis system: the CGS-MT miniature multifunctional detector station. The chamber was alternately filled with a certain amount of NO2 or dry air, and an automatic humidity-controlled gas-liquid distribution system, DGL-V, was used. During operation, the test device was first placed in the center of the heating stage and heated to the required operating temperature of 300℃ to stabilize its resistance in an air atmosphere. In a typical test, nitrogen gas was first introduced into the pneumatic valve to open the valve in the device. Humidity was dynamically controlled by a dual-flow dynamic humidity generator, DHD-Ⅱ. The response value was defined as the resistance R of the gas sensor against an air background. a With resistance R in the target gas NO2 environment g The ratio, response time, and recovery time are defined as the time required for the resistance value to change by 90% during the response and recovery processes.
[0034] Results analysis: (1) XRD analysis: The crystal structure of Ag single-atom modified In2O3 thin films grown on YSZ substrates was studied using XRD. For example... Figure 1 As shown, the material exhibits obvious XRD peaks. The indium oxide grown on the YSZ substrate corresponds to the (222) lattice plane, which conforms to the standard card (PDF #06-0416), and there are no characteristic peaks of Ag in the XRD spectrum.
[0035] (2) EXAFS analysis: The form of Ag in Ag-modified In₂O₃ films grown on YSZ substrates was investigated using XAFS. For example... Figure 2 As shown, the material corresponds to Ag-O coordination at 1.7 Å, and there is no coordination peak information in the high R region, confirming that Ag exists in the material in the form of Ag single atoms.
[0036] (3) Gas-sensitive properties: such as Figure 3 The image shows the repeatability of the Ag / In₂O₃ sensor at a NO₂ concentration of 50 ppm during five cycles of air-NO₂-air exposure at the optimal operating temperature (300℃). It can be observed that the response to NO₂ remains consistent, with a response value of 2.9, and there is no significant decay, indicating good repeatability.
[0037] The preparation method of this invention is not only applicable to the Ag / In2O3 system, but can also be extended to the modification of other noble metals (Au, Pt, Pd, etc.) or other metal oxide films (such as SnO2, ZnO, WO3, etc.), providing a general platform technology for the preparation of high-performance single-atom functional films.
[0038] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing Ag single-atom modified In₂O₃ single-crystal thin films based on pulsed voltage discharge technology, characterized in that, Includes the following steps: 1) The substrate is placed in the vacuum chamber of a magnetron sputtering equipment, and an In2O3 target is used as the In source. An indium oxide In2O3 single crystal thin film is grown on the substrate by magnetron sputtering. The substrate is yttrium oxide stabilized zirconium oxide (YSZ). 2) The indium oxide single crystal film obtained in step 1) is placed on a sample stage of a vacuum chamber equipped with a pulsed voltage discharge electrode and an Ag target. Ag particles are evaporated based on the pulsed voltage discharge process and deposited on the surface of the indium oxide single crystal film material to form dispersed clusters. After annealing, an Ag single atom modified In2O3 single crystal film is obtained.
2. The method for preparing Ag single-atom modified In₂O₃ single-crystal thin films based on pulsed voltage discharge technology according to claim 1, characterized in that, In step 1), the substrate is cleaned sequentially with acetone, anhydrous ethanol, and deionized water before being placed in the vacuum chamber of the magnetron sputtering equipment.
3. The method for preparing Ag single-atom modified In₂O₃ single-crystal thin films based on pulsed voltage discharge technology according to claim 1, characterized in that, In step 1), the magnetron sputtering process specifically includes: S1, evacuating the vacuum chamber and then heating the substrate to 400-600°C at a heating rate of 30°C / min; S2. Set the magnetron sputtering equipment to 80-100W, introduce argon gas, and pre-sputter the In2O3 target for 2-5 minutes to clean it. S3. Argon and oxygen are introduced into the vacuum chamber, and the argon-oxygen ratio in the vacuum chamber is adjusted to 10:1~5:1, the total pressure is 0.40Pa~2.0Pa, the power is 80W~100W, and the sputtering time is 10min~30min.
4. The method for preparing Ag single-atom modified In₂O₃ single-crystal thin films based on pulsed voltage discharge technology according to claim 1, characterized in that, In step 2), the Ag target is used as the discharge cathode or placed in front of the cathode, and the distance between the sample stage and the Ag target is 5-30 cm.
5. The method for preparing Ag single-atom modified In₂O₃ single-crystal thin films based on pulsed voltage discharge technology according to claim 1, characterized in that, In step 2), the process of evaporating Ag particles based on pulsed voltage discharge to deposit them on the surface of indium oxide single crystal thin film material to form dispersed clusters specifically involves: first, evacuating the vacuum chamber to a background vacuum level not exceeding 1.0 × 10⁻⁶. -3 Pa, then argon gas is continuously introduced as the working gas to maintain the chamber pressure at 0.1-10 Pa; then a high-voltage pulse power supply is applied to the pulse voltage discharge electrode to evaporate Ag particles and deposit them on the surface of the indium oxide single crystal thin film material to form dispersed clusters.
6. The method for preparing Ag single-atom modified In₂O₃ single-crystal thin films based on pulsed voltage discharge technology according to claim 5, characterized in that, The specific pulse parameters for applying the high-voltage pulse power supply to the pulse voltage discharge electrode are: pulse voltage 1-20 kV, pulse frequency 10-1000 Hz, and pulse width 1-300 mm. s.
7. The method for preparing Ag single-atom modified In₂O₃ single-crystal thin films based on pulsed voltage discharge technology according to claim 1, characterized in that, In step 2), the deposition time is 30 seconds to 30 minutes. After deposition, the sample is annealed under vacuum or protective atmosphere at room temperature to 400 °C.
8. An Ag-modified In₂O₃ single-crystal thin film prepared based on pulsed voltage discharge technology, characterized in that, It is prepared by the method described in any one of claims 1-7.
9. A gas sensor for detecting low concentration NO2, characterized in that, The Ag single-atom modified In2O3 single-crystal thin film material as described in claim 8 is used as the sensitive layer material.
10. The gas sensor for detecting low concentration NO2 according to claim 9, characterized in that, The low concentration is below 100 ppm.