CN112782153A - Tungsten trioxide-palladium-platinum composite nano-film optical fiber hydrogen sensor - Google Patents
Tungsten trioxide-palladium-platinum composite nano-film optical fiber hydrogen sensor Download PDFInfo
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- CN112782153A CN112782153A CN201911068508.4A CN201911068508A CN112782153A CN 112782153 A CN112782153 A CN 112782153A CN 201911068508 A CN201911068508 A CN 201911068508A CN 112782153 A CN112782153 A CN 112782153A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/21—Polarisation-affecting properties
Abstract
The invention discloses a tungsten trioxide-palladium-platinum composite nano film optical fiber hydrogen sensor, which consists of a broadband light source, a polaroid, a polarization controller, a test gas chamber, a flowmeter, a hydrogen and nitrogen source, a composite nano film optical fiber sensor and a demodulator; the sensor is composed of WO3‑Pd2The device comprises a Pt-Pt composite nano film and a fiber core without a cladding, and is completely sealed in a test air chamber, light emitted by a broadband light source enters a polarization controller through a polaroid and enters the left end of a sensor, a hydrogen and nitrogen gas source introduces a hydrogen and nitrogen mixed gas into the test air chamber through an air inlet, the concentration change of the hydrogen in the test air chamber is monitored through a flowmeter, and the right end of the test air chamber is connected with a demodulator. Since the optical property of the composite nano material is changed after the composite nano material reacts with hydrogen, the evanescent field property of the part of the area is also changed correspondingly. Monitoring of hydrogen with different concentrations can be realized by monitoring the change of the transmission spectrum。
Description
Technical Field
The invention belongs to the field of hydrogen sensors, and particularly relates to a tungsten trioxide-palladium-platinum composite nano-film microstructure optical fiber hydrogen sensor.
Background
In the present society, due to the limited nature of fossil fuels and the greenhouse effect and environmental pollution caused by fossil fuels, clean new energy becomes a research hotspot for global development and utilization. The hydrogen energy has the advantages of high combustion efficiency, no pollution of products and the like, is called as nine new energy sources with solar energy, wind energy and the like, and is praised as a secondary energy source with the best development prospect. Meanwhile, hydrogen is also an important industrial raw material, and has wide application in the fields of electronic industry, automobile industry, metallurgical industry, petrochemical industry, float glass, fine organic synthesis, aerospace, food processing and the like.
Hydrogen is a colorless, odorless, nontoxic, flammable and explosive gas. The hydrogen has small molecular weight, is easy to leak in the processes of production, storage, transportation and use, and has strong permeability. Meanwhile, the ignition point of hydrogen is 585 ℃, and when the hydrogen content in the air is in the range of 4% to 75%, explosion occurs when exposed fire occurs, which causes great inconvenience to storage, use, and the like of hydrogen. In view of the wide use of hydrogen in the fields of food hygiene, energy power, military and national defense, and the like, and the potential danger, the concentration of hydrogen must be detected when hydrogen is used.
The current type sensor has stable performance and can be between 0 and 104The hydrogen concentration is rapidly detected in the range of ppm, the response time of the sensor is 30s, and the sensitivity is 4uA/100 ppm. Dougongheng et al prepared a basic structure of H based on a polymer solid electrolyte2，Pt|Nafion-117|Pt，O2(air) three-electrode galvanic hydrogen sensors. But temperature, pressure and humidity changes have a large effect on the sensor measurement. The potential sensor measures the hydrogen concentration by measuring the potential difference between the sensing electrode and the reference electrode, has wider application range, and can detect the hydrogen content in gas, aqueous solution and dissolved metal at normal temperature or high temperature. Maffei et al made a basic structure of H2The potentiometric hydrogen sensor of Pd | Hyceram | Ag-Hyceram | Ag can measure the hydrogen content in the air because it uses a palladium working electrode, but it is difficult to determine a specific reliable data relationship because the potentiometric hydrogen sensor has a logarithmic relationship with the hydrogen concentration.
The resistance type hydrogen sensor is mostly a semiconductor metal oxide sensor, tin oxide is used as a sensitive material, the average response time is 4s to 20s, and the concentration of measurable hydrogen is 10ppm to 20 ppm. The single metal oxide is not highly selective to hydrogen, and a metal material having good selectivity to hydrogen, such as palladium, platinum, or the like, may be doped to improve the selectivity. Tonny-Roksana rashi et al covers a layer of 8nm thick palladium nano-film on a ZnO nanobelt, and the hydrogen concentration range measurable at room temperature is 0.2ppm to 1000ppm, and the response speed is fast and the performance is stable. But it has poor selectivity to hydrogen and is very vulnerable to interference from other reducing gases, such as methane, carbon monoxide, alcohols, etc. For a non-resistance type hydrogen sensor, Ivan Ryger and the like use a Pt/NiO Schottky hydrogen sensor to perform experiments on hydrogen with the concentration of 100ppm to 1000ppm at the temperature of 50 ℃ to 250 ℃, and find that the Pt/NiO Schottky hydrogen sensor has a good detection effect on 1000ppm of hydrogen at 50 ℃. But the temperature required by the work is higher, the energy consumption is increased, electric sparks are easy to generate during the work, and the method is not suitable for detecting the hydrogen concentration in flammable and explosive places.
With the rapid development of the related technologies of the sensors, the specific advantages of the optical fiber sensor are continuously highlighted and rapidly promoted on schedule in the occasions where the traditional electric sensing is not applicable. There are also many studies based on optical type hydrogen sensors. The structure and manufacturing process of the micro-lens type optical fiber hydrogen sensor are simple, only a sensitive film needs to be prepared on the cut and flat optical fiber end face, the cost is low, and the use is convenient. The evanescent field type optical fiber hydrogen sensor is very sensitive to hydrogen and has quick response, and the characteristics of the sensor can be controlled by the type and content of the catalyst; it is also possible to make multiple evanescent field sensors on a single fiber to achieve distributed measurements, but the manufacturing process for such sensors is relatively complex, the interference type optical fiber hydrogen sensor has the advantages of high measurement precision, good repeatability, small error and the like theoretically, but the sensor is easily influenced by external environmental factors (mainly temperature), the fiber grating type fiber hydrogen sensor is influenced by the oxidation-reduction principle, the recovery time of the sensor is longer, and the sensor is limited by the performance of the hydrogen sensitive material, the sensor does not respond to less than 0.6% hydrogen at 25 ℃, and meanwhile, because LPFG is too sensitive, the sensor only has good response under ideal conditions of a laboratory. Therefore, no hydrogen sensor with ideal performance exists in the market at present, Chinese scholars also continue to research the Pd alloy hydrogen sensor, and the hydrogen sensor which can work at room temperature and has high response speed is developed.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a micro-structure optical fiber hydrogen sensor of a tungsten trioxide-palladium-platinum composite nano film (11), wherein a sensing film layer structure of the hydrogen sensor is composed of the tungsten trioxide-palladium-platinum composite nano film (11), the refractive index and the volume of the tungsten trioxide-palladium-platinum sensitive nano film (11) can be changed after hydrogen is absorbed, and the change of a transmission spectrum is monitored by a demodulator (8) to realize the monitoring of hydrogen with different concentrations. Therefore, the problems of low response speed to hydrogen, high response concentration, low precision and the like of the traditional Pd membrane sensor at room temperature are solved.
The invention is realized by the following technical scheme: a tungsten trioxide-palladium-platinum composite nano film (11) optical fiber hydrogen sensor is composed of a broadband light source (1), a polaroid (2), a polarization controller (3), a test gas chamber (4), a flowmeter (5), a hydrogen and nitrogen source (6), an optical fiber sensor (7) of the composite nano film (11) and a demodulator (8); the method is characterized in that: the sensor (7) is composed of a tungsten trioxide-palladium-platinum composite nano film (11) and a naked fiber core (10) with a cladding (12) removed and is completely sealed in the test gas chamber (4), light emitted by the broadband light source (1) enters the polarization controller (3) through the polaroid (2) and then enters the left end of the sensor (7), hydrogen and nitrogen mixed gas is introduced into the test gas chamber (4) through the gas inlet (13) by the hydrogen and nitrogen source (6), the concentration change of the hydrogen in the test gas chamber (4) is monitored through the flowmeter (5), and the right end of the test gas chamber (4) is connected with the demodulator (8). Monitoring of hydrogen with different concentrations can be achieved by monitoring changes of the transmission spectrum.
The sensor is a microstructure sawtooth-shaped optical fiber, the optical fiber sensor (7) is a sawtooth-shaped optical fiber surface plated with a composite nano film (11), the depth range of sawteeth is 20-100 micrometers, the width of the sawteeth is 100 micrometers, the number range of the sawteeth is 3-100, and the composite nano film (11) is a tungsten trioxide, palladium and platinum layered structure. The composite nano-film (11) with determined thickness is plated by using a sensing head plating technology.
The working principle of the invention is as follows: light emitted by the broadband light source (1) enters the polarization controller (3) through the polarizing film (2), and forms an electromagnetic field-evanescent field at the fiber core (10) of the optical fiber after passing through the sensor (7). And the field strength of the evanescent field decays exponentially along the core diameter direction. Therefore, the cladding (12) at the sensor (7) needs to be removed, and the tungsten trioxide-palladium-platinum composite nano film (11) is in the action range of an evanescent field. The optical property of the composite nano material (11) is changed after the reaction with the hydrogen, and the property parameters of the evanescent field of the area are correspondingly changed, so that the change of the hydrogen concentration in the corresponding environment can be obtained by detecting the intensity or the phase of the light passing through the area. The performance test of the hydrogen sensor comprises a response time test, a sensor hydrogen circulation test and a hydrogen concentration test.
The invention has the beneficial effects that: the special micro-structure sawtooth structure can enable a plurality of MZ interference structures to be cascaded together, so that an evanescent field is enhanced, and optical transmission performance better than that of a common single-mode optical fiber is obtained. WO3Good adhesion to optical fiber, and WO3-Pd2The Pt-Pt nano composite film has good mechanical property, so that the sensing probe has certain long-term reliability3The volume exposed to hydrogen gas hardly expands, and alloying Pd with Pt can greatly suppress the change in the lattice constant of Pd. Meanwhile, the sensor also shows good resolution and accuracy in ultra-low concentration trace monitoring (0-0.1%), and has good application prospect.
Drawings
FIG. 1 is a schematic diagram of a tungsten trioxide-palladium-platinum composite nano-film optical fiber hydrogen sensor test system.
FIG. 2 is a schematic view of a microstructure of a tungsten trioxide-palladium-platinum composite nano-film optical fiber sensor.
Detailed Description
As shown in fig. 1, the tungsten trioxide-palladium-platinum composite nano film (11) optical fiber hydrogen sensor is composed of a broadband light source (1), a polarizing plate (2), a polarization controller (3), a test gas chamber (4), a flowmeter (5), a hydrogen and nitrogen source (6), an optical fiber sensor (7) of the composite nano film (11), and a demodulator (8); the method is characterized in that: the sensor (7) is composed of a tungsten trioxide-palladium-platinum composite nano film (11) and a naked fiber core (10) with a cladding (12) removed and is completely sealed in the test gas chamber (4), light emitted by the broadband light source (1) enters the polarization controller (3) through the polaroid (2) and then enters the left end of the sensor (7), hydrogen and nitrogen mixed gas is introduced into the test gas chamber (4) through the gas inlet (13) by the hydrogen and nitrogen source (6), the concentration change of the hydrogen in the test gas chamber (4) is monitored through the flowmeter (5), and the right end of the test gas chamber (4) is connected with the demodulator (8). Monitoring of hydrogen with different concentrations can be achieved by monitoring changes of the transmission spectrum. Removing partial coating of microstructure fiber with fiber cutter, and depositing 200nm WO3Film, oxygen as process gas in evaporation process, 3.33x10-6m3The speed of the/S is continuously charged, then the Bestech magnetron sputtering system is used, in WO3Sputtering 20nm Pd on the surface of the film2And the thickness of the sensitive film is monitored in real time by using a crystal oscillator system in the sputtering process.
Firstly, nitrogen is introduced into the test gas chamber (4), and after a few minutes, introduction of 3% strength hydrogen is started. There is a significant increase in light intensity at the higher cladding mode wavelengths of the spectrum. After nitrogen gas is introduced, the light intensity is basically recovered. Compared with the light intensity peak value change of the spectrum, the wavelength drift of the sensor is very weak. The peak value of the 1567nm spectrum peak is selected, and the intensity change of the peak value in the circulating hydrogen test process is measured.
A method for testing the hydrogen concentration of a tungsten trioxide-palladium-platinum composite nano film (11) microstructure optical fiber hydrogen sensor comprises the following steps: firstly, introducing nitrogen for a period of time, slowly opening hydrogen after the airflow is stable, keeping the flow constant, and gradually increasing the hydrogen flow to record the response of the sensor under different concentrations. And (4) introducing hydrogen with different concentrations in sequence, and testing and analyzing the hydrogen concentration of the sensor.
Claims (1)
1. A tungsten trioxide-palladium-platinum composite nano-film optical fiber hydrogen sensor is composed of a broadband light source (1), a polaroid (2), a polarization controller (3), a test air chamber (4), a flowmeter (5), a hydrogen and nitrogen source (6), a sensor (7) of a composite nano-film (11) and a demodulator (8); the method is characterized in that: the sensor (7) consists of a tungsten trioxide-palladium-platinum composite nano film (11) and a naked fiber core (10) with a removed cladding (12) and is completely sealed in the test air chamber (4), the sensor (7) is a sawtooth-shaped optical fiber surface plated composite nano film (11), the depth range of sawteeth is 20-100 micrometers, the width of the sawteeth is 100 micrometers, the number range of the sawteeth is 3-100, and the composite nano film (11) is of a tungsten trioxide, palladium and platinum layer structure; light emitted by the broadband light source (1) is incident into the polarization controller (3) through the polarizing disc (2) and then enters the left end of the sensor (7), hydrogen and nitrogen mixed gas is introduced into the test gas chamber (4) through the hydrogen and nitrogen source (6) through the air inlet (13), the concentration change of the hydrogen in the test gas chamber (4) is monitored through the flow meter (5), and the right end of the test gas chamber (4) is connected with the demodulator (8).
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| CN201911068508.4A CN112782153A (en) | 2019-11-05 | 2019-11-05 | Tungsten trioxide-palladium-platinum composite nano-film optical fiber hydrogen sensor |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113321427A (en) * | 2021-07-20 | 2021-08-31 | 上海交通大学 | WO capable of rapidly changing color by hydrogen3Film and preparation method thereof |
| CN115931981A (en) * | 2023-01-09 | 2023-04-07 | 南方电网数字电网研究院有限公司 | Hydrogen sensor and preparation method thereof |
| CN115931981B (en) * | 2023-01-09 | 2024-04-26 | 南方电网数字电网研究院有限公司 | Hydrogen sensor and preparation method thereof |
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2019
- 2019-11-05 CN CN201911068508.4A patent/CN112782153A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113321427A (en) * | 2021-07-20 | 2021-08-31 | 上海交通大学 | WO capable of rapidly changing color by hydrogen3Film and preparation method thereof |
| CN115931981A (en) * | 2023-01-09 | 2023-04-07 | 南方电网数字电网研究院有限公司 | Hydrogen sensor and preparation method thereof |
| CN115931981B (en) * | 2023-01-09 | 2024-04-26 | 南方电网数字电网研究院有限公司 | Hydrogen sensor and preparation method thereof |
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