An LSPR hydrogen detection device based on palladium nanoring arrays

Abstract

The present invention belongs to the technical field of hydrogen detection, and provides an LSPR hydrogen detection device based on a palladium nanoring array, which includes an optical detection unit, a sensing unit, and a data recording and processing unit. The optical detection unit is used to transmit the light emitted by the light source to the optical probe through an optical fiber, and then the optical probe irradiates the palladium nanoring array and the substrate in the sensing unit in parallel. When the palladium nanoring array undergoes a local surface plasmon resonance phenomenon, a strong resonance absorption peak will appear in the spectrum. The optical fiber in the data recording and processing unit will transmit the transmitted light and scattered light passing through the palladium nanoring array and the substrate to a spectrophotometer for measuring the scattered or extinction spectrum, and the computer terminal will perform data analysis and processing on the resonance absorption peak in the spectrum measured by the spectrophotometer to achieve hydrogen concentration detection. The present invention has the advantages of not generating sparks, not being affected by electromagnetic interference, being able to remotely read data, and not being affected by harsh environments.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen detection, and particularly relates to an LSPR hydrogen detection device based on a palladium nanoring array. Background Art

[0002] As a pollution-free, renewable and sustainable new energy, hydrogen has been widely used in many fields such as aerospace, fuel cells, medical applications, oil exploration, chemical processing, etc. However, due to its smallest molecular weight, hydrogen has extremely strong diffusivity and permeability, is colorless and odorless, so it is very easy to leak and difficult to detect. In addition, hydrogen's low ignition energy (0.018 mJ), high combustion heat (285.8 kJ / mol) and wide explosion concentration range (4%-75%) make it a highly flammable and explosive dangerous gas. Therefore, the detection of hydrogen is of great significance for the safety of industrial manufacturing and daily life.

[0003] Currently, traditional hydrogen sensors based on electrochemical properties have been developed and widely used in various fields. Electrochemical hydrogen sensors are based on the electrochemical reaction between hydrogen and the sensing electrode, which causes a change in charge transfer or electrical properties, thereby realizing the detection of hydrogen concentration. For example, Chinese Patent CN201110335970.3 discloses a three-electrode solid electrolyte hydrogen sensor and a hydrogen concentration measurement method using this sensor. By measuring the electromotive force E1 between the first measurement electrode and the reference electrode, and the electromotive force E2 between the second measurement electrode and the reference electrode, calculating the ratio of the two electromotive forces, and then calculating to obtain the hydrogen concentration. However, such electrochemical hydrogen sensors have potential electric sparks, and their selectivity for hydrogen is non-specific. They are even interfered by the ambient temperature, resulting in errors. The structures of hydrogen sensors in other applied patents are complex (such as CN201921101612.4, an electrochemical hydrogen sensor based on a solid electrolyte) or use liquid electrolytes (such as CN202110400850.0, a hydrogen sensor and its application), which have problems such as leakage and corrosion, and are costly.

[0004] Therefore, in view of the deficiencies of traditional electrochemical hydrogen sensors in terms of safety and gas selectivity, it has become an urgent need to invent a hydrogen detection device that can achieve hydrogen detection and is safe and sensitive. Summary of the Invention

[0005] To solve the above problems, the present invention provides an LSPR (Localized Surface Plasmon Resonance) hydrogen detection device based on a palladium nanoring array, which has the advantages of not generating sparks, not being affected by electromagnetic interference, being able to remotely read data, and not being affected by harsh environments.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] An LSPR hydrogen detection device based on a palladium nanoring array, comprising an optical detection unit, a sensing unit, and a data recording and processing unit.

[0008] The optical detection unit includes a light source, an optical fiber, and an optical probe; the sensing unit includes a substrate, a palladium nanoring array, and a gas chamber with controllable gas components; the data recording and processing unit includes a spectrophotometer, an optical probe, an optical fiber, and a computer terminal.

[0009] In the sensing unit, the palladium nanoring array is grown on the substrate, and the substrate is vertically placed in the gas chamber with controllable gas components; mounting holes are provided at the front and rear ends of the gas chamber with controllable gas components for mounting the optical probe, and the optical probes are arranged oppositely on both sides of the substrate; an interface is provided on the side of the gas chamber with controllable gas components for introducing the hydrogen to be detected.

[0010] In the optical detection unit, the optical probe is mounted in the mounting hole on the side of the gas chamber with controllable gas components close to the palladium nanoring array, and the light source is connected to the optical probe through an optical fiber.

[0011] In the data recording and processing unit, the optical probe is mounted in the mounting hole on the side of the gas chamber with controllable gas components close to the substrate, and the spectrophotometer is connected to the optical probe through an optical fiber; the computer terminal is connected to the spectrophotometer through an optical fiber.

[0012] The light emitted by the light source in the optical detection unit is transmitted to the optical probe through the optical fiber, and is parallelly irradiated onto the palladium nanoring array and the substrate in the sensing unit by the optical probe. The palladium nanoring array exhibits the phenomenon of local surface plasmon resonance (LSPR), and a strong resonance absorption peak will appear in the spectrum. The transmitted light and scattered light passing through the palladium nanoring array and the substrate are transmitted to the spectrophotometer by the optical probe in the data recording and processing unit through the optical fiber for measuring the scattering or extinction spectrum, and the computer terminal performs data analysis and processing on the resonance absorption peak in the spectrum measured by the spectrophotometer to achieve hydrogen concentration detection.

[0013] Further, the spectral range of the light source is 190nm - 2500nm, and the light source is a halogen lamp, an LED lamp, a mercury lamp, or a sodium lamp;

[0014] Further, the optical fiber in the optical detection unit is a single-core optical fiber;

[0015] Further, the substrate is made of a glass sheet;

[0016] Further, the structure of the palladium nanoring array is a hexagonal periodic array structure;

[0017] Further, the gas chamber with controllable gas components is filled with nitrogen and hydrogen.

[0018] The beneficial effects of the present invention are as follows:

[0019] 1. The present invention uses the LSPR optical principle to detect hydrogen, which will not be interfered by external factors such as environmental temperature and humidity, and has extremely high stability;

[0020] 2. The present invention is pollution-free. The entire palladium nanoring array is in the shape of a hexagonal periodic array. Compared with other nanoarray structures, the hexagonal palladium nanoring array structure has a higher coupling strength, which helps to improve gas sensitivity to achieve rapid concentration measurement, has a wide measurement range, and since the palladium nanoring array only interacts with hydrogen and will not be interfered by other gases such as carbon monoxide, carbon dioxide, and methane, it has high specificity;

[0021] 3. The present invention analyzes the resonance absorption peaks in the spectrum measured by the spectrophotometer through a computer terminal, which can not only detect hydrogen, but also construct the numerical relationship between the changes in the position, intensity, line width and other characteristics of the resonance absorption peaks in the spectrum and the hydrogen concentration, so as to achieve accurate detection of hydrogen concentration;

[0022] 4. The present invention has a simple structure, low cost, small size, light weight, and is convenient to carry, which can meet the needs of hydrogen detection in laboratories, factories, etc., and is convenient for popularization. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of the overall structure of an LSPR hydrogen detection device based on a palladium nanoring array.

[0024] Figures 2(a) to 2(c) is a schematic diagram of different angles of the palladium nanoring array on the glass slide.

[0025] In the figure: 1 light source; 2 optical fiber a; 3 optical probe a; 4 palladium nanoring array; 5 substrate; 6 gas chamber with controllable gas components; 7 optical fiber b; 8 spectrophotometer; 9 computer terminal; 10 glass slide; 11 hexagonal palladium nanoring array; 12 outer diameter of a single palladium nanoring; 13 inner diameter of a single palladium nanoring; 14 thickness of a single palladium nanoring; 15 center distance between adjacent two palladium nanorings; 16 optical probe b. DETAILED DESCRIPTION OF THE INVENTION

[0026] The following further describes the specific embodiments of the present invention in conjunction with the drawings and technical solutions.

[0027] The present invention provides an LSPR hydrogen detection device based on a palladium nanoring array, as Figure 1As shown in the figure, it includes an optical detection unit, a sensing unit, and a data recording and processing unit; the optical detection unit includes a light source 1, an optical fiber a2, and an optical probe a3; the sensing unit includes a palladium nanoring array 4, a substrate 5, and a gas chamber 6 with controllable gas components; the data recording and processing unit includes an optical probe b16, an optical fiber b7, a spectrophotometer 8, and a computer terminal 9. Specifically as follows:

[0028] The optical detection unit is used to emit light of different wavelengths through the light source 1 and transmit it to the optical probe a3 through the optical fiber a2 in the optical detection unit, so as to irradiate the palladium nanoring array 4 and the substrate 5 in parallel through the optical probe 3. When the frequency of the incident photons matches the overall vibration frequency of the conduction electrons excited by the fixed positive ion cores in the palladium nanoparticle lattice of the palladium nanoring array 4, the palladium nanoparticles will have a strong absorption effect on the photon energy, and the phenomenon of local surface plasmon resonance (LSPR) will occur. At the wavelength where resonance occurs, the palladium nanoparticles will strongly absorb and scatter light, and a strong resonance absorption peak will appear in the spectrum. The wavelength at which LSPR occurs depends on several factors such as the size, shape, and material of the nanoparticles, but also on its surrounding environment, that is, its dielectric properties. Therefore, by tracking the LSPR wavelength, any changes in the nanoparticles themselves (through changes in size, shape, or material electronic properties) or their surrounding environment (through changes in the surrounding dielectric properties) can be detected. The former sensing principle can be called direct plasmon sensing, and the latter can be called indirect plasmon sensing. The present invention adopts direct plasmon sensing and is composed of metal nanoparticles palladium that forms hydrides. The palladium nanoring array 4 reacts with hydrogen in the gas chamber 6 with controllable gas components. When hydrogen is absorbed into the palladium nanometal lattice, palladium nanoparticles form PdH x , resulting in palladium expansion. At the same time, the dielectric constant of metallic palladium also changes, thereby causing the resonance absorption peak of LSPR to shift. The optical probe b16 in the data recording and processing unit will transmit the transmitted light and scattered light passing through the palladium nanoring array 4 and the substrate 5 to the spectrophotometer 8 through the optical fiber b7 for measuring the scattering or extinction spectrum. The computer terminal 9 detects the hydrogen concentration by analyzing the changes in the position, intensity, and linewidth of the LSPR resonance absorption peak in the scattering or extinction spectrum measured by the spectrophotometer 8.

[0029] Furthermore, the spectral range of the light source 1 in the optical detection unit is 190nm - 2500nm. The light source 1 is a halogen lamp, or an LED lamp, or a mercury lamp, or a sodium lamp. The optical fiber a2 in the optical detection unit is a single-core optical fiber.

[0030] Further, the substrate 5 is made of a glass sheet, which is used to support the entire palladium nanoring array 4, and at the same time, it facilitates the transmission and scattering of incident light.

[0031] Further, the gas chamber 6 with controllable gas components is filled with nitrogen and hydrogen, and the concentration of hydrogen released is precisely controlled by a flow controller.

[0032] Further, the computer terminal 9 constructs a numerical relationship between the changes in characteristics such as the position, intensity, and line width of the resonance absorption peaks in the spectrum measured by the spectrophotometer 8 and the hydrogen concentration, so as to achieve precise detection of the hydrogen concentration.

[0033] Figures 2(a) to 2(c) It is a schematic diagram of a palladium nanoring array. The entire palladium nanoring array is composed of a hexagonal palladium nanoring array 11 located above the glass sheet 10 arranged periodically. The outer diameter 12 of a single palladium nanoring is 200 nm, the inner diameter 13 is 150 nm, the thickness 14 is 100 nm, the center-to-center distance 15 between adjacent palladium nanorings is 350 nm, and the size of the entire palladium nanoring array is 50 μm × 50 μm.

[0034] In this embodiment, the preparation method of the palladium nanoring array is as follows:

[0035] First, select a glass sheet with a size of 1 cm × 1 cm, and then wash it with dishwashing liquid, deionized water, acetone, and isopropanol for 10 minutes each. Each time the solution is changed, it is necessary to pre-wash with the next solution. After washing, blow it dry with nitrogen.

[0036] A layer of PMMA glue is spin-coated on the washed glass sheet by spin-coating technology. After low-speed spinning at 400 rpm for 9 seconds and then high-speed spinning at 3000 rpm for 30 seconds, it is placed on a constant-temperature heating table at 150 °C for 10 minutes to volatilize the solvent in the PMMA coating, and then cooled to room temperature to obtain a substrate with spin-coated photoresist.

[0037] The pattern generator controls the electron beam to draw the pattern of the palladium nanoring structure to be exposed on the photoresist.

[0038] The glass sheet spin-coated with the electron beam etching resist PMMA is horizontally fixed on the workpiece table with a copper sheet. After focusing and field calibration, electron beam exposure is carried out. The exposure area is controlled by NPGS. The exposure parameters are set as follows: the exposure voltage is 30 keV, the exposure current is 100 pA, the exposure dose is 180 fc, and then it is developed in the developer for 60 seconds; a mixed solution of methyl isobutyl ketone (MIBK) and isopropanol (IPA) prepared according to a volume ratio of 1:3 is used as the developer. After development, it is fixed and cleaned with ionized water, alcohol, or a solvent that does not dissolve the photoresist such as isopropanol for 20 - 30 seconds.

[0039] A layer of palladium is sputtered on the sample with a lithography pattern by using a magnetron sputtering process. The sputtering environment is set to a vacuum degree lower than 1.5×10 -4 Pa, and it is set that: the sputtering power is 140 W, the sputtering gas pressure is 0.8 Pa, and the sputtering time is 1.5 hours to obtain a glass sheet containing a palladium film;

[0040] Finally, the glass sheet deposited with the palladium film is put into an acetone solution and ultrasonically cleaned in an ultrasonic cleaner for 5 minutes to remove the PMMA layer, taken out and dried with nitrogen, and then baked on a constant temperature heating table at 100 °C for 3 minutes to obtain a regularly arranged palladium nanoring array structure.

[0041] The above-mentioned LSPR hydrogen detection device based on the palladium nanoring array provided by the present invention can be used to monitor the hydrogen concentration in a nuclear power plant cooling system or a power transformer, etc., and has a wide application prospect in hydrogen safety detection in many fields such as aerospace engineering, oil exploration, metallurgical refineries, cryogenic cooling, chemical processing, and automobiles.

Claims

1. An LSPR hydrogen detection device based on a palladium nanoring array, characterized in that, The described LSPR hydrogen detection device based on a palladium nanoring array includes an optical detection unit, a sensing unit, and a data recording and processing unit; The optical detection unit includes a light source, an optical fiber, and an optical probe; the sensing unit includes a substrate, a palladium nanoring array, and a gas chamber with controllable gas components; the data recording and processing unit includes a spectrophotometer, an optical probe, an optical fiber, and a computer terminal; In the sensing unit, the palladium nanoring array is grown on the substrate. The palladium nanoring array structure is a hexagonal periodic array structure. The substrate is vertically placed in the gas chamber with controllable gas components. Mounting holes are provided at the front and rear ends of the gas chamber with controllable gas components for mounting the optical probe. The optical probes are arranged oppositely on both sides of the substrate. An interface is provided on the side of the gas chamber with controllable gas components for introducing the hydrogen to be detected; In the optical detection unit, the optical probe is mounted in the mounting hole on the side of the gas chamber with controllable gas components close to the palladium nanoring array. The light source is connected to the optical probe through an optical fiber. The optical fiber in the optical detection unit is a single-core optical fiber; In the data recording and processing unit, the optical probe is mounted in the mounting hole on the side of the gas chamber with controllable gas components close to the substrate. The spectrophotometer is connected to the optical probe through an optical fiber; the computer terminal is connected to the spectrophotometer through an optical fiber; The light emitted by the light source in the optical detection unit is transmitted to the optical probe through the optical fiber and is parallelly irradiated onto the palladium nanoring array and the substrate in the sensing unit by the optical probe. The palladium nanoring array exhibits the phenomenon of local surface plasmon resonance (LSPR), and a resonance absorption peak appears in the spectrum. The transmitted light and scattered light passing through the palladium nanoring array and the substrate are transmitted to the spectrophotometer by the optical probe in the data recording and processing unit through the optical fiber for measuring the scattered or extinction spectrum. The computer terminal performs data analysis and processing on the resonance absorption peak in the spectrum measured by the spectrophotometer to achieve hydrogen concentration detection.

2. The LSPR hydrogen detection device based on a palladium nanoring array according to claim 1, wherein The spectral range of the light source is 190 nm to 2500 nm. The light source is a halogen lamp, an LED lamp, a mercury lamp, or a sodium lamp.

3. The LSPR hydrogen detection device based on a palladium nanoring array according to claim 1, wherein The substrate is made of a glass sheet.

4. The LSPR hydrogen detection device based on a palladium nanoring array according to claim 1, characterized in that, The gas chamber with controllable gas components is filled with nitrogen and hydrogen.

Images