Optical hydrogen sensing material, preparation method thereof, and method for optical response detection of hydrogen concentration
By controlling the deposition rate of Pd nanoparticles and preparing a disordered Pd nanoparticle assembly film, the problem of unstable baseline of Pd thin film hydrogen sensor at room temperature was solved, and a stable hydrogen optical sensing effect was achieved.
Patent Information
- Application Number
- CN202211488700.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-11-25
- Publication Date
- 2025-09-09
- Estimated Expiration
- 2042-11-25
AI Technical Summary
Existing Pd thin film hydrogen sensors are susceptible to hydrogen embrittlement at room temperature, resulting in unstable sensing baselines and affecting the consistency and stability of the sensor.
Cluster beam deposition technology is used to prepare Pd nanoparticle-assembled discontinuous films. The deposition rate is controlled between 0.05 and 0.2 Å/s to form a discontinuous film structure with densely arranged disordered Pd nanoparticles, avoiding nanoparticle agglomeration and achieving stable baseline hydrogen optical sensing.
By controlling the deposition rate, the prepared Pd nanoparticle assembled film exhibits a stable optical response baseline at room temperature, which improves the stability and sensitivity of the sensor and is suitable for large-scale production.
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Figure CN115791658B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of gas sensing, and in particular to an optical hydrogen sensing material and a preparation method thereof, and a method for optically responding to hydrogen concentration. Background Art
[0002] Due to its high combustion efficiency and pollution-free products, hydrogen, along with solar energy and nuclear energy, is considered one of the three major new energy sources and has been widely used in various industrial fields. However, hydrogen molecules are very small and prone to leakage during production, storage, transportation, and use. Hydrogen is unbreathable, colorless, and odorless, making it imperceptible to the human sense of smell. Its ignition point is only 585°C, and its air concentration ranges from 4% to 75%, making it explosive when exposed to open flames. Therefore, hydrogen sensors are essential for monitoring the ambient hydrogen content and leak detection. One of the key technologies in the development of hydrogen energy is the development of hydrogen sensors that ensure the safe use of hydrogen.
[0003] Palladium (Pd) metal has a d-shell electronic structure that can reversibly adsorb hydrogen at room temperature and produce changes in its photoelectric properties. It is a common and widely used hydrogen sensing material. When a continuous Pd film interacts with hydrogen, the hydrogen embrittlement effect will cause the Pd film to crack, and the sensing baseline will drift severely, thus affecting the consistency and stability of the sensor. Compared with the continuous Pd film structure, the non-continuous film assembled from Pd nanoparticles is less susceptible to the hydrogen embrittlement effect. In fact, the optical properties of metal nanoparticles in the visible and near-infrared bands are affected by the size, morphology, composition and aggregation morphology of the nanoparticles. In theory, Pd nanoparticle-assembled films with relatively orderly particle size and aggregation distribution and no agglomeration are relatively easier to achieve stable baseline hydrogen sensing behavior.
[0004] In previous research, the applicant used cluster beam deposition technology to prepare Pd nanoparticle assembly materials to construct electrical hydrogen sensors (for example, see the literature: Sun L, Chen M, Peng X, et al. The effects of Ni contents on hydrogen sensing response of closely spaced Pd–Nialloy nanoparticle films[J]. International Journal of Hydrogen Energy, 2016,41(2): 1341-1347.). We found that this Pd nanoparticle assembly structure can also map the external hydrogen concentration through changes in optical signals. At the same time, we also found that by reducing the deposition rate of Pd nanoparticles, the agglomeration behavior between nanoparticles in the Pd nanoparticle assembly material can be greatly suppressed, thereby obtaining a hydrogen sensing material with a more stable baseline. Based on this discovery, the applicant filed this invention patent application. Summary of the Invention
[0005] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art and provide an optical hydrogen sensing material and a preparation method thereof, and a method for optically detecting hydrogen concentration. The optical hydrogen sensing material of the present invention has a stable optical response baseline when detecting hydrogen concentration.
[0006] To achieve the above objectives, the present invention utilizes physical vapor deposition technology to prepare Pd nanoparticle assembly materials through cluster beam deposition technology and realizes hydrogen optical sensing. It proposes to prepare Pd nanoparticle assembled discontinuous films at a lower deposition rate to avoid nanostructure agglomeration caused by excessively fast deposition rate, thereby achieving stable baseline hydrogen sensing behavior under room temperature conditions.
[0007] The optical hydrogen sensing material is characterized by comprising a highly transparent quartz plate as a substrate and a Pd nanoparticle-assembled thin film attached to the surface of the quartz plate. The preparation method is to deposit Pd nanoparticles on the surface of the highly transparent quartz plate at a low deposition rate based on cluster beam deposition technology. The deposition rate is controlled at 0.05-0.2 Å / s and the deposition time is 2500-3500 s, so that the surface of the highly transparent quartz plate forms a discontinuous thin film structure composed of densely arranged disordered Pd nanoparticles with a certain visible light absorbance, namely, a hydrogen gas-sensitive film.
[0008] The optical hydrogen sensing material is characterized in that the Pd nanoparticle coverage in the Pd nanoparticle assembled film is controlled at 30-60%.
[0009] The method for preparing an optical hydrogen sensing material is characterized by comprising the following steps:
[0010] 1) Place a high-purity Pd target on the sputtering gun of the cluster beam deposition equipment, place a high-transmittance quartz substrate in the deposition chamber of the cluster beam deposition system, and evacuate the entire device;
[0011] 2) Sputtering gas is introduced into the sputtering gun, and buffer gas is introduced into the sputtering chamber of the cluster beam deposition system;
[0012] 3) A power of 3 to 12 W is applied to the sputtering gun to partially vaporize the Pd target into gaseous molecules or atoms, which are then collided with the buffer gas to form nanoparticles. A nanoparticle beam is formed through differential pumping, and then the beam is directed into the deposition chamber of the cluster beam deposition equipment and deposited on the surface of a placed quartz wafer. The deposition rate of the Pd nanoparticles is controlled at 0.05 to 0.2 Å / s, and the time for depositing the Pd nanoparticles on the quartz substrate is 2500 to 3500 s, thus obtaining a hydrogen gas-sensitive film.
[0013] The method for preparing an optical hydrogen sensing material is characterized in that in step 2), high-purity argon gas with a purity of more than 99.99% is used as sputtering gas and buffer gas, and the gas pressure in the sputtering chamber is maintained at 80~120Pa.
[0014] The method for preparing an optical hydrogen sensing material is characterized in that in step 2), 60 sccm of sputtering gas is introduced into the sputtering gun, and 70 sccm of buffer gas is introduced into the sputtering chamber.
[0015] The method for preparing an optical hydrogen sensing material is characterized in that in step 3), a power of 6 W is supplied to the sputtering gun, the deposition rate of the Pd nanoparticles is controlled at 0.1 Å / s, and the time for depositing the Pd nanoparticles on the quartz substrate is 3000 s.
[0016] The method for detecting the optical response of the optical hydrogen sensing material to the hydrogen concentration is characterized by comprising the following steps:
[0017] S1: placing the optical hydrogen sensing material in a gas-sensitive test chamber, turning on the light source and spectrometer, allowing the visible light of the spectrometer to pass through the quartz plate, measuring the extinction spectrum of the Pd nanoparticle assembled film, measuring the light absorption spectrum in the range of 200-800 nm, determining the plasmon resonance peak of the Pd nanoparticles, and then determining the wavelength position of the plasmon resonance peak;
[0018] S2: The gas-sensing test chamber is evacuated, and the Pd nanoparticle assembled thin film of the optical hydrogen sensing material faces the visible incident light beam emitted by the light source. The transmitted light passes through the window of the gas-sensing test chamber and enters the spectrometer. Then, hydrogen at a specific pressure is filled into the gas-sensing test chamber. During this process, the measurement wavelength of the spectrometer is set to the resonance peak position obtained in step S1. The variation of the transmitted light intensity with the hydrogen pressure is measured according to this method, and a real-time variation curve of the transmitted light intensity with the hydrogen pressure of the optical hydrogen sensing material is obtained. The relationship between the transmittance and hydrogen pressure of the sample is obtained from this curve.
[0019] S3: When measuring the hydrogen concentration of the actual gas, the transmitted light intensity of the optical hydrogen sensing material under the actual gas atmosphere is tested according to the method of step S2, and then substituted into the real-time change curve obtained in step S2 to infer the hydrogen concentration in the actual gas.
[0020] The present invention tests the hydrogen response performance of a Pd nanoparticle-assembled thin film by rotating a quartz substrate to allow visible light from a spectrometer to pass through the quartz plate, measuring the extinction spectrum of the Pd-Pd nanoparticle-assembled thin film, obtaining the Pd nanoparticle plasmon resonance peak from the spectrum, and then determining the peak position. The spectrometer wavelength is set to the plasmon resonance peak position, and the signal intensity of the transmitted light is continuously monitored. Simultaneously, a certain concentration of hydrogen is circulated. Due to the chemical interaction between the hydrogen and the Pd nanoparticles, the signal displayed on the spectrum changes. The relationship between the transmitted light signal intensity and the hydrogen concentration is measured to obtain the hydrogen response characteristics of the hydrogen-sensitive material.
[0021] The present invention achieves the following beneficial effects: It uses vapor deposition technology to deposit nanoparticle assembly materials. Compared to traditional wet chemical methods, the prepared materials are purer and compatible with existing microelectronics processes, possessing the potential for large-scale production. Because the nanoparticle assembly material formed by sputtering has a higher specific surface area than a thin film, it significantly increases its exposure to hydrogen, creating more reaction sites and exhibiting fast response speed and high sensitivity. More importantly, by controlling the deposition rate of the Pd nanoparticles, a non-agglomerated, discontinuous assembly film can be obtained, ensuring the stability of the sensing baseline. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 It is a schematic diagram of the structure of the Pd nanoparticle assembled film of the present invention.
[0023] 1-Pd nanoparticle assembled film, 2-quartz substrate.
[0024] Figure 2 It is a schematic diagram of a hydrogen response testing device for a hydrogen gas sensitive film assembled from Pd nanoparticles of the present invention.
[0025] 3-gas-sensitive test chamber, 4-light source, 5-spectrometer, 6-incident light, 7-transmitted light, 8-valve, 9-exhaust port, 10-intake port.
[0026] Figure 3 It is the extinction spectrum of the hydrogen gas sensitive film assembled from Pd nanoparticles of the present invention.
[0027] Figure 4a The graph is a real-time response curve of the hydrogen gas sensitive film assembled from Pd nanoparticles prepared at a low deposition rate to hydrogen gas at different pressures of 300-5000 kP.
[0028] Figure 4b The invention discloses a relationship between the responsiveness of the hydrogen gas sensitive film assembled from Pd nanoparticles prepared at a low deposition rate to hydrogen gas at different pressures of 300-5000 kPa and the hydrogen gas pressure.
[0029] Figure 5a This is the real-time response curve of the hydrogen gas sensitive film assembled by Pd nanoparticles prepared at a high deposition rate to hydrogen at different pressures of 300~5000kP.
[0030] Figure 5b It is the relationship between the responsiveness of the hydrogen gas sensitive film assembled by Pd nanoparticles prepared at a high deposition rate to hydrogen gas at different pressures of 300~5000kPa and the hydrogen pressure. DETAILED DESCRIPTION
[0031] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.
[0032] Example 1: A method for preparing an optical hydrogen-sensitive film, comprising the following steps:
[0033] (1) Preparation of Pd nanoparticle assembled thin films: Place a high-purity Pd target on the sputtering gun of the cluster beam deposition equipment, place a high-transmittance quartz substrate in the deposition chamber of the cluster beam deposition system, and evacuate the entire device to a vacuum of 5×10 -5 Pa.
[0034] (2) 60 sccm of sputtering gas was introduced into the sputtering gun, and 70 sccm of buffer gas was introduced into the sputtering chamber. High-purity argon gas with a purity of more than 99.99% was used as the sputtering gas and buffer gas. At this time, the pressure in the sputtering chamber was 100 Pa, and 6 W of power was introduced into the sputtering gun. The deposition rate was measured by a crystal oscillator microbalance to be approximately 0.1 Å / s. The deposition was carried out on the quartz substrate for approximately 3000 s, and the Pd nanoparticle coverage was controlled at approximately 60%, ensuring that it was within the visible light absorption wave range, thus obtaining the hydrogen gas-sensitive film designed by the present invention, as shown in FIG. Figure 1As shown, it includes a Pd nanoparticle assembly film 1 and a quartz substrate 2.
[0035] A hydrogen gas-sensing test of an optical hydrogen gas-sensing film comprises the following steps:
[0036] (1) If Figure 2 As shown, the Pd nanoparticle assembled film (including the quartz substrate) obtained by the above deposition process is placed in a gas-sensing test chamber 3. The light source 4 and spectrometer 5 are turned on. The sample position is adjusted so that it faces the visible incident light beam 6. The transmitted light 7 enters the spectrometer 5 after passing through the window of the chamber. The optical absorption spectrum is measured in the range of 200-800nm, and the position of the plasmon resonance peak is determined to be 472nm, as shown in FIG. Figure 3 shown.
[0037] (2) Open valve 8 to evacuate the gas-sensitive test chamber 3, and the gas is discharged from the exhaust port 9. Then, hydrogen gas at a specific pressure is filled into the chamber from the inlet port 10. During this process, the measurement wavelength of the spectrometer is set at the resonance peak position (i.e., 472 nm), and the change of the transmitted light intensity over time is measured. The real-time change curve of the sample transmitted light intensity with hydrogen pressure is obtained, as shown in Figure 2. Figure 4a As shown. Through this curve, we can get the relationship between the transmittance and hydrogen pressure of the sample, as shown in Figure 4b shown.
[0038] According to the above preparation process, 60 sccm of sputtering gas was introduced into the sputtering gun, 70 sccm of buffer gas was introduced into the sputtering chamber, and high-purity argon with a purity of more than 99.99% was used as the sputtering gas and buffer gas. At this time, the pressure in the sputtering chamber was 100 Pa, and 24 W of power was introduced into the sputtering gun. Another sample was prepared under the condition of a deposition rate of about 1.4 Å / s. The real-time curve of hydrogen response was measured as shown below. Figure 5a As shown. The relationship between its transmittance and hydrogen pressure is also obtained, as shown in Figure 5b shown.
[0039] Comparing the two samples, it can be seen that the sample obtained at a low deposition rate exhibits a relatively stable sensing baseline, while the sample obtained at a high deposition rate exhibits significant baseline drift each time hydrogen is introduced (especially within the low hydrogen pressure range). Therefore, the optical hydrogen-sensing film based on Pd nanoparticle-assembled thin films, produced by low-rate cluster beam deposition, proposed in this invention, exhibits a stable sensing baseline, ensuring sensor detection accuracy and overcoming the unstable baseline issues of existing Pd metal hydrogen sensors.
[0040] The contents described in this specification are merely an enumeration of implementation forms of the inventive concept, and the protection scope of the present invention should not be considered as being limited to the specific forms described in the embodiments.
Claims
1. A method for optically detecting hydrogen concentration using an optical hydrogen sensing material, characterized in that The optical hydrogen sensing material comprises a highly transparent quartz substrate and a Pd nanoparticle-assembled thin film attached to the surface of the quartz. The preparation method is based on cluster beam deposition technology, which deposits Pd nanoparticles on the surface of the highly transparent quartz at a low deposition rate. The method specifically includes the following steps: 1) Place a high-purity Pd target on the sputtering gun of the cluster beam deposition equipment, place a high-transmittance quartz substrate in the deposition chamber of the cluster beam deposition system, and evacuate the entire device; 2) Sputtering gas is introduced into the sputtering gun, and buffer gas is introduced into the sputtering chamber of the cluster beam deposition system; 3) The sputtering gun is supplied with a power of 3 to 12 W, and the deposition rate of the Pd nanoparticles is controlled at 0.05 to 0.2 Å / s. The Pd nanoparticles are deposited on the quartz substrate for 2500 to 3500 seconds, so that a non-continuous thin film structure composed of densely packed disordered Pd nanoparticles with a certain visible light absorbance is formed on the surface of the highly transparent quartz wafer, thereby obtaining a hydrogen gas-sensitive film. In the Pd nanoparticle assembled film, the Pd nanoparticle coverage is controlled at 30-60%; The detection method comprises the following steps: S1: placing the optical hydrogen sensing material in a gas-sensitive test chamber, turning on the light source and spectrometer, allowing the visible light of the spectrometer to pass through the quartz plate, measuring the extinction spectrum of the Pd nanoparticle assembled film, measuring the light absorption spectrum in the range of 200-800 nm, determining the plasmon resonance peak of the Pd nanoparticles, and then determining the wavelength position of the plasmon resonance peak; S2: The gas-sensing test chamber is evacuated, and the Pd nanoparticle assembled thin film of the optical hydrogen sensing material faces the visible incident light beam emitted by the light source. The transmitted light passes through the window of the gas-sensing test chamber and enters the spectrometer. Then, hydrogen at a specific pressure is filled into the gas-sensing test chamber. During this process, the measurement wavelength of the spectrometer is set to the resonance peak position obtained in step S1. The variation of the transmitted light intensity with the hydrogen pressure is measured according to this method, and a real-time variation curve of the transmitted light intensity with the hydrogen pressure of the optical hydrogen sensing material is obtained. The relationship between the transmittance and hydrogen pressure of the sample is obtained from this curve. S3: When measuring the hydrogen concentration of the actual gas, the transmitted light intensity of the optical hydrogen sensing material under the actual gas atmosphere is tested according to the method of step S2, and then substituted into the real-time change curve obtained in step S2 to infer the hydrogen concentration in the actual gas.
2. The detection method according to claim 1, wherein In step 2), high-purity argon gas with a purity of more than 99.99% is used as sputtering gas and buffer gas, and the pressure in the sputtering chamber is maintained at 80~120Pa.
3. The detection method according to claim 1, wherein In step 2), 60 sccm of sputtering gas is introduced into the sputtering gun, and 70 sccm of buffer gas is introduced into the sputtering chamber.
4. The detection method according to claim 1, wherein In step 3), a power of 6 W is supplied to the sputtering gun, the deposition rate of the Pd nanoparticles is controlled at 0.1 Å / s, and the time for depositing the Pd nanoparticles on the quartz substrate is 3000 s.