Vanadium dioxide nanobelt hydrogen sensor based on phase transition amplification and preparation method thereof

Abstract

The present application belongs to the technical field of nanobelt gas sensor, and particularly relates to a vanadium dioxide nanobelt hydrogen sensor based on phase change amplification and a preparation method thereof. The sensor has simple driving mode, low critical working voltage and wide detection range, and has super-high sensitivity, super-low detection lower limit, super-fast response and recovery speed and excellent low-temperature adaptability. The device structure is easy to integrate, and the process parameters can be controlled in a directional manner. The sensor can be adapted to various hydrogen energy safety monitoring scenes such as vehicle hydrogen storage, outdoor low temperature and portable detection, has irreplaceable application advantages in the fields of hydrogen leakage real-time early warning and low-concentration hydrogen precise detection, and provides a new technical scheme and practical path for the development of high-sensitivity sensor devices in related fields such as gas molecule detection and quality detection. The sensor has wide industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of nanoribbon gas sensor technology, specifically relating to a vanadium dioxide (VO2) nanoribbon hydrogen sensor based on phase change amplification and its preparation method. Background Technology

[0002] Hydrogen energy is crucial for driving energy transition and achieving the "dual-carbon" goal. However, hydrogen is highly susceptible to leakage and has a wide explosive range. Therefore, hydrogen sensors are core components for ensuring the safety of the entire hydrogen production, storage, transportation, and application industry chain. Currently, domestic and international hydrogen sensors are mainly based on electrochemical, catalytic combustion, and semiconductor technologies. Foreign products are technologically mature but have complex structures and high costs. Although domestic research has made progress, it still generally suffers from insufficient sensitivity at low temperatures, slow response recovery, and difficulty in achieving low-concentration detection, making it difficult to meet the demands of high-performance, easily integrated sensors for scenarios such as on-board hydrogen storage and outdoor low-temperature applications. Therefore, developing new high-performance hydrogen sensing technologies suitable for wide-temperature-range, low-concentration detection, and breaking through the current sensing performance bottlenecks, has become a key scientific and engineering problem that urgently needs to be solved in the field of hydrogen energy safety. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a hydrogen sensor based on phase transition amplification of vanadium dioxide nanoribbons and its preparation method. Relying on the intrinsic insulator-metal ultrafast phase transition characteristics of VO2 nanoribbons, combined with the efficient hydrogen overflow catalytic mechanism of noble metal sensitive layer and critical voltage precise amplification technology, a high-gain, low-power hydrogen sensing system is constructed.

[0004] To achieve the aforementioned objective, the present invention provides a vanadium dioxide nanoribbon hydrogen sensor based on phase change amplification, comprising a VO2 nanoribbon, a sensitive layer, and a metal electrode disposed on a silicon substrate. The metal electrode includes a source and a drain connected to an external circuit, which are used to realize the input of the excitation signal and the output of the response signal, respectively. A gap is provided between the VO2 nanoribbon and the substrate silicon wafer, and the two ends of the VO2 nanoribbon are fixed to the source and drain electrodes respectively through fixed ends to form an ohmic contact; The fixed end includes a first fixed end and a second fixed end. The first fixed end fixes one end of the VO2 nanoribbon to the source electrode, and the second fixed end fixes the other end of the VO2 nanoribbon to the drain electrode. The sensitive layer is positioned at the midpoint of the VO2 nanoribbon, which enhances the detection of hydrogen.

[0005] The external circuit includes a DC power supply and a digital multimeter; the DC power supply is connected to the source and drain, and is used to provide a bias voltage to the VO2 nanoribbon so that it reaches the threshold neighborhood and approaches the phase transition trigger point; The digital multimeter is connected in series with the VO2 nanoribbon via wires to the source and drain terminals, and is used to detect changes in the resistance of the VO2 nanoribbon.

[0006] Preferably, the above-mentioned method for preparing the VO2 nanoribbon hydrogen sensor based on phase transition amplification includes the following steps: S1. After activating the silicon wafer with polished and oxidized surface, it is sequentially cleaned, dehydrated and surface film formed to obtain a pretreated substrate silicon wafer. A layer of photoresist is uniformly coated on the surface of the substrate silicon wafer and pre-baking is performed to form the first photoresist layer. S2. The first photoresist layer is exposed on the photolithography machine using the first mask, and then the substrate silicon wafer is developed. After the substrate silicon wafer is patterned, a gold thin film (such as gold or silver) with a thickness of 60~100 nm is deposited on the substrate silicon wafer using an electron beam evaporation process. The excess metal film on the deposited silicon substrate is removed using a peeling process to form the metal electrode source and drain. S3. Single-crystal VO2 nanoribbons were prepared on a quartz substrate by chemical vapor deposition. S4. Using a tungsten probe, the VO2 nanoribbons dispersed on the glass plate are transferred to the source and drain ends. Platinum (Pt) is deposited on both ends of the VO2 nanoribbons using focused ion beam (FIB) technology to form two rectangular platinum metal blocks as the first and second fixed ends to flatten and fix the VO2 nanoribbons. S5. First, spin-coat a 200 nm photoresist layer on the surface of the fixed VO2 nanoribbon, and expose the midpoint of the VO2 nanoribbon at the midpoint under a scanning electron microscope. Then, deposit a sensitive layer in the vapor phase and use a lift-off process to obtain a VO2 nanoribbon sensor with a midpoint coated sensitive layer. S6. Connect the DC power supply to the source and drain terminals with wires, and also connect the digital multimeter to the source and drain terminals to obtain the VO2 nanobelt hydrogen sensor based on phase change amplification.

[0007] Preferably, in step S3, the preparation process of the VO2 nanoribbons includes: S31. Place 0.5 g of commercial VO2 powder with a purity of 99% in a quartz boat and then place it in the center of a horizontal tube furnace, and place an unpolished (rough) quartz substrate 5 mm above the bottom of the quartz boat to obtain higher vapor density and deposition temperature; S32. Evacuate the furnace tube to a basic pressure of 1.33 Pa, and then purge it with argon (Ar); increase the temperature at a rate of 15℃ / min and maintain it at the target temperature of 900℃~950℃ for 5~6 hours; and maintain the pressure at 1333 Pa throughout the entire reaction process. S33. After the reaction is complete, wait for the tube furnace to cool to room temperature, then take out the unpolished (rough) quartz substrate with VO2 nanoribbons grown on it. Use a thin blade to scrape off the VO2 nanoribbons and soak them in 5 ml of ethanol solution. After dispersing them evenly with an ultrasonic cleaner, use a pipette to take 10 μl and drop it onto a glass slide.

[0008] Preferably, in step S1, the activation temperature of the silicon wafer activation is 500~700 K, and the activation time is 20~40 min; the pre-baking treatment temperature is 373~383 K, and the time is 50~60 s; the photoresist is polymethyl methacrylate (PMMA) photoresist, the exposure dose is 50~500 µC / cm², and the development time is 100~120 s.

[0009] Preferably, in step S4, the single-crystal VO2 nanoribbon has a width of 10-20 μm, a length of 150-200 μm, and an aspect ratio of 8-20 as the sensor reaction region.

[0010] Preferably, in step S4, the transfer process of the single-crystal VO2 nanoribbons includes: S41. First, use a tungsten probe to peel the VO2 nanoribbons off the glass slide, then apply a 5V voltage to adsorb and transfer the VO2 nanoribbons. S42. Place the VO2 nanoribbon on the source and drain, then turn off the applied voltage to release the VO2 nanoribbon, and finally complete the transfer.

[0011] Preferably, in step S2, the metal material for electron beam evaporation is gold, the evaporation rate is 0.5~2 Å / s, and the vacuum degree is less than 1×10⁻⁶. –4 Pa.

[0012] Preferably, in step S4, the length of the first fixed end and the second fixed end are both 30 μm, the width is both 20 μm, and the thickness is both 2 μm.

[0013] Preferably, in step S5, the material used to prepare the sensitive layer also includes noble metals such as palladium and platinum, which are used to dissociate hydrogen molecules into hydrogen ions through the hydrogen spillover effect, and the sensitive layer is deposited at the midpoint of the VO2 nanoribbon with a deposition width of 50~100 μm.

[0014] Preferably, the vanadium dioxide nanoribbon hydrogen sensor based on phase transition amplification is used to construct an ultra-high sensitivity sensor.

[0015] The beneficial effects of this invention are reflected in: (1) Ultra-high sensitivity and significant resistance jump: This invention locks the operating point of the VO2 nanoribbon near the insulator-metal phase transition threshold voltage by precisely controlling the critical bias voltage, placing the device in the most sensitive operating range for electrical response. When the sensor is exposed to a hydrogen atmosphere, hydrogen is decomposed into hydrogen ions through hydrogen spillover effect under the catalytic action of the surface noble metal sensitive layer (Pt / Pd), and adsorbed and doped into the VO2 lattice, effectively reducing its phase transition threshold voltage, thereby inducing a phase transition in the system. During this process, the resistance of the VO2 nanoribbon can drop from 10... 6 The resistance drops dramatically from the Ω level to the 10³ Ω level, achieving a resistance jump of more than three orders of magnitude. This intrinsic amplification effect driven by the phase transition makes the sensor's response to hydrogen far stronger than that of traditional resistive sensors, and its sensitivity is significantly better than that of most existing semiconductor and catalytic gas sensors, enabling highly reliable detection of extremely low concentrations of hydrogen.

[0016] (2) Low detection limit and wide range response capability: This invention uses critical voltage modulation to ensure that the VO2 nanoribbon always operates at the sensitive inflection point of the phase transition threshold, exhibiting extremely high response gain to weak external stimuli. The device maintains high sensitivity output across a wide concentration range, especially demonstrating excellent detection capability for low-concentration hydrogen, achieving accurate identification of hydrogen concentrations as low as 1 ppm, with a clear response signal and high signal-to-noise ratio. Furthermore, by flexibly adjusting the critical operating voltage, it can be adapted and optimized for different concentration ranges, balancing the needs of low-concentration detection and high-concentration safety alarms, thus possessing the advantages of a wide detection range and high dynamic range.

[0017] (3) Ultrafast response speed for real-time detection: This invention utilizes the intrinsic ultrafast phase transition characteristics of VO2 and the efficient carrier transport channel of one-dimensional nanoribbons, combined with the rapid adsorption / desorption kinetics of hydrogen ions, to enable the sensor to have an extremely fast response speed. When hydrogen is introduced, hydrogen ions rapidly regulate the phase transition voltage and trigger a sharp drop in resistance (≥3 orders of magnitude). The intrinsic electrical switching time of the VO2 phase transition can reach the picosecond (ps) level, which is superior to the second-to-second response speed of traditional metal oxide sensors. The ultrafast response enables real-time detection and instantaneous early warning of hydrogen leaks, significantly improving the safety and reliability of hydrogen energy systems under extreme operating conditions. Attached Figure Description

[0018] Figure 1 This is a flowchart of the VO2 nanoribbon hydrogen sensor based on phase transition amplification prepared in Example 1 of the present invention; Figure 2 This is a schematic planar view of the VO2 nanoribbon hydrogen sensor based on phase transition amplification prepared in Example 1 of the present invention; Figure 3 This is a three-dimensional schematic diagram of the VO2 nanoribbon hydrogen sensor based on phase transition amplification prepared in Example 1 of the present invention.

[0019] Figure labels and descriptions: 100. Substrate silicon wafer; 101. First photoresist layer; 102. VO2 nanoribbon; 103. First fixed terminal; 104. Second fixed terminal; 105. Source; 106. Drain; 108. DC power supply; 109. Sensitive layer; 110. Digital multimeter. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] This invention provides a vanadium dioxide nanoribbon hydrogen sensor based on phase transition amplification and its preparation method.

[0022] VO2 is a functional material with significant insulator-metal phase transition properties, where its resistance can undergo an order-of-magnitude abrupt change in the critical phase transition region. By modifying the surface of VO2 nanoribbons with platinum or palladium noble metal layers, hydrogen molecules can be efficiently decomposed into hydrogen ions at low temperatures using the hydrogen spillover effect and injected into the VO2 lattice. The carrier concentration can be significantly controlled through the doping effect, thereby triggering a phase transition-driven dramatic change in resistance and achieving a highly sensitive response.

[0023] The sensor utilizes a dedicated electrical circuit built on VO2 nanoribbons, applying a critical bias voltage of 8-10 V to lock it within the phase transition sensitive range. Hydrogen-triggered hydrogen ion doping rapidly modulates the phase transition threshold of the nanoribbons, initiating a phase transition that causes a dramatic change in resistance of more than three orders of magnitude, enabling precise detection of hydrogen as low as 1 ppm. The high specific surface area, fast electron transport channels, and excellent stability of the VO2 nanoribbons further enhance its response speed and environmental adaptability. Simultaneously, the directional carrier transport channels of the one-dimensional nanoribbons allow for a picosecond-level sensing response speed, significantly surpassing traditional sensors.

[0024] To enhance the detection capability of weak signals at low temperatures, this invention employs phase transition amplification technology. By utilizing the nonlinear characteristics of VO2 in the critical region of phase transition, the minute electrical changes caused by hydrogen adsorption are amplified with high gain, thereby significantly improving the detection capability, signal-to-noise ratio, and low-temperature stability of low-concentration hydrogen. At the same time, it reduces power consumption and simplifies the control circuit, making it easy to achieve micro-nano integration.

[0025] For ease of explanation, three examples are provided below: Example 1 Reference Figure 1 This embodiment provides a method for fabricating a VO2 nanoribbon hydrogen sensor based on phase transition amplification, specifically: 1) Substrate pretreatment Using a surface-polished silicon oxide wafer as the substrate material, it is activated at 500 K for 20 min to improve surface cleanliness and adhesion. Then, standard cleaning, dehydration and surface film formation are performed sequentially to ensure good insulation and photoresist adhesion, resulting in a pre-treated substrate silicon wafer 100.

[0026] 2) Photoresist coating and photolithography A layer of photoresist is uniformly spin-coated onto the surface of the pretreated substrate silicon wafer 100 and pre-baked at 373 K for 50 s to form the first photoresist layer 101.

[0027] The first photoresist layer 101 is exposed on a photolithography machine using a first photomask, and then the substrate silicon wafer 100 is developed.

[0028] The photoresist used in this step is PMMA, the exposure dose is 50~500 µC / cm², and the development time is 100 s.

[0029] 3) Metal electrode evaporation and stripping The patterned silicon substrate 100 was subjected to electron beam evaporation to deposit a gold (Au) thin film in the electrode region at a deposition rate of 0.2 Å / s and a vacuum level better than 1×10⁻⁶. -4 Pa.

[0030] After evaporation, excess photoresist and surface metal are removed by lift-off process to form source 105 and drain 106. The thickness of source 105 and drain 106 is controlled at 60~100 nm to ensure good conductivity and mechanical stability.

[0031] 4) Preparation of VO2 nanoribbons 102 Single-crystal VO2 nanoribbons were prepared using chemical vapor deposition (CVD). 0.5 g of commercial VO2 powder with a purity of 99% was placed in a quartz boat and placed in the center of a horizontal tube furnace; an unpolished quartz substrate was placed 5 mm above the quartz boat to improve vapor density and deposition uniformity.

[0032] The furnace body was evacuated to 1.33 Pa and repeatedly purged with argon (Ar); the temperature was increased to 900~950 ℃ at 15 ℃ / min and held for 5~6 h, with the gas pressure maintained at 1333 Pa throughout the process.

[0033] After the reaction was completed, the furnace was cooled to room temperature, and the quartz substrate with VO2 nanoribbons was removed. The nanoribbons were scraped off with a thin blade, dispersed in 5 ml of ethanol, and sonicated until homogeneous. 10 μl of the suspension was then dropped onto a glass slide for later use.

[0034] The resulting single-crystal VO2 nanoribbons 102 have a width of 10~20 μm, a length of 150~200 μm, and an aspect ratio of 8~20, and serve as the sensitive reaction region of the sensor.

[0035] 5) VO2 nanoribbon 102 transfer and fixation A tungsten probe is used to precisely transfer the VO2 nanoribbons 102 dispersed on the glass slide to the source 105 and drain 106, so that the two ends of the VO2 nanoribbons 102 are reliably connected to the source 105 and drain 106 respectively.

[0036] Platinum (Pt) is deposited at both ends of the VO2 nanoribbon 102 in the electrode contact area using focused ion beam (FIB) technology to form two rectangular platinum metal blocks, which can serve as the first fixed end 103 and the second fixed end 104, thus making the VO2 nanoribbon 102 firmly and flatly fixed.

[0037] Fixed end dimensions: length 30 μm, width 20 μm, thickness 2 μm.

[0038] 6) Preparation of sensitive layer 109 A 200 nm thick photoresist layer was spin-coated onto the surface of the fixed VO2 nanoribbon 102; the midpoint region of the nanoribbon was precisely exposed under a scanning electron microscope, and then a platinum / palladium (Pt / Pd) noble metal sensitive layer 109 with a deposition width of 50~100 μm was deposited using a vapor deposition process.

[0039] Excess photoresist was removed by a stripping process to obtain a device structure in which the sensitive layer 109 was coated only in the VO2 nanobelt 102, and the hydrogen spillover effect was used to achieve efficient catalytic dissociation of hydrogen.

[0040] 7) Test circuit connection Connect the DC power supply 108 to the source 105 and drain 106, and apply a critical initial bias voltage of 5~10 V to make the VO2 nanobelt work in the critical sensitive range of phase transition.

[0041] A digital multimeter 110 is connected in series with the source 105 and the drain 106 via wires to monitor the resistance change signal of the VO2 nanoribbon 102 in real time.

[0042] 8) Hydrogen sensing test Hydrogen gas is introduced into the test gas path and comes into contact with the sensor. Under the action of the noble metal sensitive layer 109 at the midpoint, the hydrogen molecules are decomposed into hydrogen ions through the hydrogen spillover effect and adsorbed and doped into the VO2 lattice, triggering an ultrafast phase transition between insulator and metal. The sensor resistance changes significantly by 2 to 3 orders of magnitude, achieving highly sensitive hydrogen detection.

[0043] The VO2 nanoribbon hydrogen sensor based on phase change amplification prepared according to this embodiment has excellent sensitivity, wide detection range and fast response time, and can be widely used in the field of hydrogen detection. At the same time, the present invention also has the characteristics of being initializeable and having different sensitive layers that can be replaced.

[0044] Comparative Example 1 To investigate the effect of the aspect ratio of VO2 nanoribbon 102 on the switching voltage and power consumption of the sensor, this comparative example was set up. The preparation method, test environment and test method of this comparative example are basically the same as those of Example 1, except that the aspect ratio of VO2 nanoribbon 102 is changed. The specific differences and test results are as follows.

[0045] Under the same testing environment, the VO2 nanobelt 102 sensor was subjected to open-loop testing. Five sets of experimental data were read and the average value was taken. The results are shown in Table 1.

[0046] Table 1

[0047] As shown in Table 1, the aspect ratio of the VO2 nanoribbon 102 is positively correlated with the sensor switching voltage. That is, the smaller the aspect ratio of the VO2 nanoribbon 102, the lower the corresponding switching voltage. Under the same circuit operating system, the switching voltage directly determines the power consumption of the sensor. The lower the switching voltage, the less power consumption the sensor consumes during operation.

[0048] In this comparative example, the VO2 nanoribbon 102 with an aspect ratio of 8 exhibits a 2 V lower switching voltage compared to Example 1, demonstrating superior low-power characteristics and making it more suitable for applications with high power consumption requirements, such as portable hydrogen detection and vehicle-mounted hydrogen storage monitoring. Furthermore, it demonstrates that by adjusting the aspect ratio of the VO2 nanoribbon 102, the switching voltage and power consumption of the sensor can be optimized in a targeted manner, providing a clear direction for adjusting the sensor's process parameters to meet different application requirements.

[0049] Example 2 The only difference between this embodiment and Example 1 is the following process parameters; all other preparation steps, structures, and testing methods are exactly the same as in Example 1: The substrate activation temperature was 600 K, and the activation time was 30 min. The photoresist pre-baking temperature was 383 K for 60 s; PMMA photoresist exposure dose 100 µC / cm², development time 60 s; Electron beam evaporation electrode velocity was 0.3 Å / s, and the metal material was silver; CVD preparation of VO2 nanoribbons: target temperature 800 ℃, holding time 6 h, argon flow rate 110 sccm; The sensitive layer has a deposition width of 70 μm and is made of palladium (Pd).

[0050] The remaining steps and processes were all the same as in Example 1, and the VO2 nanobelt sensor of this example was obtained. Open-loop testing was performed on it, and the results were comparable to those of Example 1.

[0051] Example 3 The only difference between this embodiment and Example 1 is the following process parameters; all other preparation steps, structures, and testing methods are exactly the same as in Example 1: substrate activation temperature 650 K, activation time 35 min; photoresist pre-baking temperature 378 K, time 55 s; PMMA photoresist exposure dose 200 µC / cm², development time 80 s; electron beam evaporation electrode rate 0.4 Å / s, metal material is silver; CVD preparation of VO2 nanoribbons: target temperature 750 ℃, holding time 5.5 h, argon flow rate 90 sccm; sensitive layer deposition width 100 μm, sensitive layer material is platinum (Pt). All other process steps are the same as in Example 1. The resulting VO2 nanoribbon sensor was subjected to open-loop testing, and the results were comparable to those of Example 1.

[0052] Comparative Example 2 To investigate the effect of the deposition width of the sensitive layer on the resistance variation and detection sensitivity of the VO2 nanoribbon hydrogen sensor, this comparative example was set up. The preparation method, testing environment, and testing method of this comparative example are basically the same as those of Example 1, except that the deposition width of the sensitive layer 109 in the central region of the VO2 nanoribbon 102 was adjusted. The specific differences, testing process, and results analysis are as follows.

[0053] Only the deposition process parameters of the sensitive layer 109 in step 6) of Example 1 were adjusted: both methods deposited the sensitive layer in the central region of the VO2 nanoribbon 102. In this comparative example, the deposition width of the sensitive layer 109 was adjusted to 50 μm, while in Example 1, the deposition width of the sensitive layer 109 was 80 μm. All other preparation process parameters (including substrate pretreatment, metal electrode evaporation and stripping, VO2 nanoribbon 102 preparation and fixation, test circuit connection, etc.), overall sensor structure, test gas path configuration, and open-loop test operation method remained completely consistent with Example 1. Under the same temperature, humidity, gas pressure, and gas flow rate test environment as Example 1, hydrogen gas of the same concentration was introduced into both the comparative example and Example 1. Open-loop tests were performed on both sensors simultaneously, and five sets of resistance change data during the hydrogen-induced insulator-metal phase transition of the VO2 nanoribbon 102 were collected. After removing outliers, the average value was taken as the final test result, as shown in Table 2 below, ensuring the accuracy, validity, and comparability of the test data.

[0054] Table 2

[0055] As shown in Table 2, under the premise that the deposition position of the sensitive layer 109 is at the center of the VO2 nanoribbon 102, the same concentration of hydrogen gas is introduced, and other test conditions are completely consistent, the deposition width of the sensitive layer 109 has a significant impact on the magnitude of the resistance change and the detection performance of the sensor after the phase transition. The specific conclusions are as follows: The deposition width of the sensitive layer 109 in the central region of the VO2 nanoribbon 102 is positively correlated with the magnitude of the resistance change: In Example 1, an 80 μm wide sensitive layer 109 was deposited in the center of the VO2 nanoribbon 102, and the resistance changed abruptly by three orders of magnitude after the hydrogen-induced phase transition; In this comparative example, the width was reduced to 50 μm at the same deposition location, and the magnitude of the resistance change was reduced to two orders of magnitude, which is one order of magnitude less than that in Example 1, and the response intensity of the sensing signal was significantly reduced.

[0056] A suitable deposition width enhances the efficiency of hydrogen ion doping and phase transition triggering: Depositing a sensitive layer 109 with an appropriate width in the central region of the VO2 nanobelt 102 provides more sufficient hydrogen adsorption and catalytic dissociation sites. Hydrogen ions generated by the hydrogen spillover effect can be more fully doped into the core reaction region of the VO2 nanobelt 102, more efficiently controlling the carrier concentration and electron transport characteristics of the material, thereby triggering a more intense insulator-metal phase transition and achieving a significant change in resistance. However, when the deposition width is too small (50 μm), the effective catalytic sites of the sensitive layer 109 are insufficient, the amount and range of hydrogen ion doping are limited, the phase transition triggering effect is weakened, and only a small change in resistance can be achieved.

[0057] A larger resistance change directly improves the sensor's detection performance: the greater the resistance change, the more significant the sensor output signal and the higher the signal-to-noise ratio. This not only greatly improves the detection sensitivity of hydrogen but also facilitates the accurate identification of low-concentration hydrogen. At the same time, a more significant resistance change makes the correspondence between gas concentration and electrical signal clearer, further improving the sensor's measurement accuracy and detection reliability.

[0058] Comparative Example 3 The difference between this comparative example and Example 1 is that the material of the sensor is adjusted to indium oxide (In2O3), and the resistance change is compared with that of the VO2 nanoribbon 102 in the example when the same quantitative concentration of hydrogen gas is introduced.

[0059] Under the same testing environment, open-loop tests were conducted on the VO2 nanoribbon sensor and the In2O3 nanoribbon sensor. Five sets of experimental data were read and the average value was taken. The results are shown in Table 3.

[0060] Table 3

[0061] As shown in Table 3, the VO2 nanoribbon sensor in Example 1 of this application exhibits a 1000-fold change in resistance during the phase transition upon contact with hydrogen, while the In2O3 nanoribbon sensor shows only a 20-fold change in resistance. Clearly, the VO2 nanoribbon sensor exhibits a greater resistance change in hydrogen detection, which is beneficial for improving the sensor's response value and thus its sensitivity.

[0062] In summary, this invention utilizes the phase transition properties of VO2 nanoribbons 102 to improve the sensor's sensitivity and expand its detection range by transitioning from an insulating phase to a metallic phase. Furthermore, by depositing the sensitive layer 109 at the midpoint of the VO2 nanoribbons 102 to ensure uniform adsorption, the sensor's sensitivity can also be improved. All these optimizations contribute to enhancing the sensor's performance.

[0063] In addition to the optimization measures mentioned above, the manufacturing method of this invention can be appropriately adjusted to adapt to different application scenarios and needs. For example, different electrode materials and sensitive layer 109 can be selected according to actual needs to reduce the manufacturing cost of the sensor and change the sensor's performance indicators such as the detected gas. Electrode materials can be metals such as copper, aluminum, and nickel to reduce the manufacturing cost of the sensor. Sensitive layer 109 can be sensitive materials such as palladium and platinum to detect different concentrations of hydrogen gas.

[0064] Therefore, the fabrication method of the VO2 nanoribbon hydrogen sensor based on phase change amplification of the present invention has the characteristics of flexibility and adjustability, and can be optimized and adjusted according to actual needs to meet different application scenarios and requirements. The sensor prepared by the fabrication method of the present invention has excellent sensitivity and stability, and can be widely used in gas detection and related fields, providing strong support for research and development in related fields.

[0065] In summary, this invention effectively solves the problems of poor low-temperature adaptability and insufficient sensitivity of existing sensors by synergistically combining VO2 nanoribbon 102 material, noble metal catalytic layer and critical voltage amplification technology. It achieves high sensitivity, fast response, low-temperature detectability and easy integration of hydrogen sensing performance, which can meet the urgent needs of the field of hydrogen energy safety monitoring for high-performance and low-power sensors.

[0066] 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 vanadium dioxide nanoribbon hydrogen sensor based on phase transition amplification, characterized in that, It includes VO2 nanoribbons (102), a sensitive layer (109), and metal electrodes disposed on a silicon substrate (100); A gap is provided between the VO2 nanoribbon (102) and the substrate silicon wafer (100), and the two ends of the VO2 nanoribbon (102) are respectively fixed to the metal electrode through the fixed end to form an ohmic contact; The metal electrode includes a source (105) and a drain (106) connected to an external circuit, which are used to realize the input of the excitation signal and the output of the response signal, respectively. The fixed end includes a first fixed end (103) and a second fixed end (104). The first fixed end (103) fixes one end of the VO2 nanoribbon (102) to the source (105), and the second fixed end (104) fixes the other end of the VO2 nanoribbon (102) to the drain (106). The sensitive layer (109) is located at the midpoint of the VO2 nanoribbon (102); The external circuit includes a DC power supply (108) and a digital multimeter (110); the DC power supply (108) is connected to the source (105) and the drain (106) to provide a bias voltage to the VO2 nanoribbon (102) so that it reaches the threshold neighborhood close to the phase transition trigger point; The digital multimeter (110) is connected in series with the source (105) and drain (106) via wires to form a series connection with the VO2 nanoribbon (102) and is used to detect the change in resistance of the VO2 nanoribbon (102).

2. The method for preparing a vanadium dioxide nanoribbon hydrogen sensor based on phase transition amplification as described in claim 1, characterized in that, The preparation method includes the following steps: S1. After the silicon wafer with polished and oxidized surface is activated, it is cleaned, dehydrated and surface film formed in sequence to obtain a pretreated substrate silicon wafer (100). A layer of photoresist is uniformly coated on the surface of the substrate silicon wafer (100) and pre-baking is performed to form the first photoresist layer (101). S2. The first photoresist layer (101) is exposed on a photolithography machine using the first mask, and then the substrate silicon wafer (100) is developed. After the substrate silicon wafer (100) is patterned, a metal thin film with a thickness of 60~100 nm is deposited on the substrate silicon wafer (100) using an electron beam evaporation process. The excess metal film on the vapor-deposited silicon substrate (100) is removed by a peeling process to form the metal electrode source (105) and drain (106); S3. Single-crystal VO2 nanoribbons (102) were prepared by chemical vapor deposition. S4. Using a tungsten probe, the prepared VO2 nanoribbon (102) is transferred to the source (105) and drain (106) ends. Platinum (Pt) is deposited on both ends of the VO2 nanoribbon (102) using focused ion beam (FIB) technology to form two rectangular platinum metal blocks as the first fixed end (103) and the second fixed end (104) to flatten and fix the VO2 nanoribbon (102). S5. First, spin-coat a 200 nm photoresist on the surface of the fixed VO2 nanoribbon (102), and expose the midpoint of the VO2 nanoribbon (102) at the midpoint of the scanning electron microscope. Then, vapor-deposit a sensitive layer (109) and use a lift-off process to obtain a VO2 nanoribbon sensor with a midpoint coated sensitive layer (109). S6. Connect the DC power supply (108) to the source (105) and drain (106) with wires, and connect the digital multimeter (110) to the source (105) and drain (106) to obtain the VO2 nanobelt hydrogen sensor based on phase change amplification.

3. The method for preparing a vanadium dioxide nanoribbon hydrogen sensor based on phase transition amplification according to claim 2, characterized in that, In step S3, the preparation process of the VO2 nanoribbons (102) includes: S31. Place 0.5 g of commercial VO2 powder with a purity of 99% in a quartz boat and then place it in the center of a horizontal tube furnace, and place an unpolished quartz substrate 5 mm above the bottom of the quartz boat. S32. Evacuate the furnace tube to a basic pressure of 1.33 Pa, and then purge it with argon (Ar); increase the temperature at a rate of 15℃ / min and maintain it at the target temperature of 900℃~950℃ for 5~6 hours; and maintain the pressure at 1333 Pa throughout the entire reaction process. S33. After the reaction is complete, wait for the tube furnace to cool to room temperature, then take out the unpolished quartz substrate with VO2 nanoribbons (102) grown on it. Use a thin blade to scrape off the VO2 nanoribbons (102) and soak them in 5 ml of ethanol solution. After dispersing them evenly with an ultrasonic cleaner, use a pipette to take 10 μl and drop it onto a glass slide.

4. The method for preparing a vanadium dioxide nanoribbon hydrogen sensor based on phase transition amplification according to claim 2, characterized in that, In step S1, the activation temperature of the silicon wafer activation is 500~700 K, and the activation time is 20~40 min; the pre-baking treatment temperature is 373~383 K, and the time is 50~60 s; the photoresist is polymethyl methacrylate photoresist, the exposure dose is 50~500 µC / cm², and the development time is 100~120 s.

5. The method for preparing a vanadium dioxide nanoribbon hydrogen sensor based on phase transition amplification according to claim 2, characterized in that, In step S4, the width of the single-crystal VO2 nanoribbon (102) is 10-20 μm and the length is 150-200 μm.

6. The method for preparing a vanadium dioxide nanoribbon hydrogen sensor based on phase transition amplification according to claim 2, characterized in that, In step S4, the transfer process of the single-crystal VO2 nanoribbon (102) includes: S41. First, use a tungsten probe to peel the VO2 nanoribbons (102) off the glass plate, and then apply a voltage of 5V to adsorb the VO2 nanoribbons (102) for transfer. S42. Place the VO2 nanoribbon (102) on the source (105) and drain (106), then turn off the additional voltage to release the VO2 nanoribbon (102), and finally complete the transfer.

7. The method for preparing a vanadium dioxide nanoribbon hydrogen sensor based on phase transition amplification according to claim 2, characterized in that, In step S2, the metal material used for electron beam evaporation is gold, the evaporation rate is 0.5~2 Å / s, and the vacuum degree is less than 1×10⁻⁶. –4 Pa.

8. The method for preparing a vanadium dioxide nanoribbon hydrogen sensor based on phase transition amplification according to claim 2, characterized in that, In step S4, the length of the first fixed end (103) and the second fixed end (104) are both 30 μm, the width is both 20 μm, and the thickness is both 2 μm.

9. The method for preparing a vanadium dioxide nanoribbon hydrogen sensor based on phase transition amplification according to claim 2, characterized in that, In step S5, the materials used to prepare the sensitive layer (109) also include palladium and platinum, and the sensitive layer (109) is deposited at the midpoint of the VO2 nanoribbon (102) with a deposition width of 50~100 μm.

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