Hydrogen sensitive film and multichannel optical fiber hydrogen sensing system comprising same

Abstract

The invention discloses a hydrogen sensitive film and a multichannel optical fiber hydrogen sensing system comprising the same, the hydrogen sensitive film is a MoO3-PdPt-Pt composite film, and the hydrogen sensitive film comprises a MoO3 layer, a PdPt layer and a Pt layer which are sequentially laminated; the multi-channel optical fiber hydrogen sensing system comprises a light source, an optical fiber splitter, a sensor probe, a photoelectric detector and a signal processing display which are electrically connected; wherein the sensor probe comprises a single-mode optical fiber and a hydrogen sensitive film deposited at the end part of the single-mode optical fiber; according to the multichannel optical fiber hydrogen sensing system, the multichannel optical path and the sensor probe are combined, the hydrogen concentration monitoring cost is reduced, the multichannel optical fiber hydrogen sensing system has the advantages of being long in monitoring distance, high in safety, large in hydrogen monitoring capacity and high in hydrogen response rate, and safe and rapid monitoring of hydrogen leakage at multiple positions of a hydrogen-related place is facilitated.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic technology, and in particular to a hydrogen sensitive film and a multi-channel optical fiber hydrogen sensing system comprising the same. Background Art

[0002] Hydrogen energy is a secondary energy source that is abundant in source, green, low-carbon and widely used. It is very important to use hydrogen sensors to detect colorless, odorless, flammable and explosive hydrogen to ensure the safety of hydrogen use.

[0003] Compared with electrochemical hydrogen sensors, fiber optic hydrogen sensors use weak light signals as transmission media, and have advantages such as safety, resistance to electromagnetic interference, and corrosion resistance, and are expected to be applied on a large scale in flammable, explosive, and harsh environments. However, fiber optic hydrogen sensors not only have high system costs, but also have defects such as insufficient monitoring capacity and slow response rate, which are not conducive to accurate monitoring of hydrogen concentration.

[0004] Therefore, there is an urgent need to provide a solution to improve the monitoring effect of hydrogen. Summary of the invention

[0005] In view of this, the present application provides a hydrogen sensitive film and a multi-channel optical fiber hydrogen sensing system comprising the same, which are used to solve the problem of how to improve the hydrogen monitoring effect.

[0006] In order to achieve the above technical objectives, this application adopts the following technical solutions: In a first aspect, the present application provides a hydrogen sensitive film, which is a MoO3-PdPt-Pt composite film, comprising a MoO3 layer, a PdPt layer and a Pt layer stacked in sequence.

[0007] Preferably, the thickness of the MoO3 layer is 80-400 nm, the thickness of the PdPt layer is 10-40 nm, and the thickness of the Pt layer is 2-10 nm.

[0008] Preferably, in the PdPt layer, the Pt atomic content is 5-50%, and the Pd atomic content is 50-95%.

[0009] In a second aspect, the present application provides a method for preparing a hydrogen sensitive film, comprising the following steps: S1. Using MoO3 particles as raw materials, a MoO3 layer is deposited on the surface of the substrate by vacuum evaporation method; S2. Using Pd target and Pt target as raw materials, a PdPt layer is deposited on the surface of the MoO3 layer by magnetron sputtering; S3. Using Pt target as raw material, a Pt layer is deposited on the surface of the PdPt layer by magnetron sputtering, and the obtained MoO3-PdPt-Pt composite film is a hydrogen sensitive film.

[0010] In a third aspect, the present application provides a sensor probe comprising a hydrogen sensitive film, including a single-mode optical fiber and a hydrogen sensitive film deposited on the end of the single-mode optical fiber; the MoO3 layer of the hydrogen sensitive film is bonded to the end of the single-mode optical fiber.

[0011] Preferably, the diameter of the single-mode optical fiber is 80-100 μm.

[0012] Preferably, it further comprises a protection tube sleeved on the single-mode optical fiber, and epoxy resin is filled between the single-mode optical fiber and the protection tube.

[0013] In a fourth aspect, the present application provides a multi-channel optical fiber hydrogen sensing system, including an electrically connected light source, an optical fiber splitter, a sensor probe, a photodetector, and a signal processing display.

[0014] Preferably, the fiber optic splitter includes a first fiber optic splitter, a second fiber optic splitter, a third fiber optic splitter, a fourth fiber optic splitter, a fifth fiber optic splitter, and a sixth fiber optic splitter; the photodetector includes a first photodetector, a second photodetector, a third photodetector, a fourth photodetector, and a fifth photodetector; the sensor probe includes a first sensor probe, a second sensor probe, a third sensor probe, and a fourth sensor probe; the input end of the first fiber optic splitter is electrically connected to the light source, and the output end of the first fiber optic splitter is divided into two paths and connected in parallel with the input end of the first photodetector and the input end of the second fiber optic splitter; the output end of the second fiber optic splitter is divided into four paths and connected in parallel with the input end of the third fiber optic splitter, the input end of the fourth fiber optic splitter, the input end of the fifth fiber optic splitter, and the input end of the sixth fiber optic splitter; the third The first output end of the optical fiber splitter, the first output end of the fourth optical fiber splitter, the first output end of the fifth optical fiber splitter, and the first output end of the sixth optical fiber splitter are correspondingly connected to the first sensor probe, the second sensor probe, the third sensor probe, and the fourth sensor probe; the second output end of the third optical fiber splitter, the second output end of the fourth optical fiber splitter, the second output end of the fifth optical fiber splitter, and the second output end of the sixth optical fiber splitter are correspondingly connected to the input end of the second photodetector, the input end of the third photodetector, the input end of the fourth photodetector, and the input end of the fifth photodetector; the output end of the first photodetector, the output end of the second photodetector, the output end of the third photodetector, the output end of the fourth photodetector, and the output end of the fifth photodetector are electrically connected in parallel to the photodetectors and the signal processing display.

[0015] Preferably, the first fiber optic splitter, the third fiber optic splitter, the fourth fiber optic splitter, the fifth fiber optic splitter, and the sixth fiber optic splitter are all 1 / 2 fiber optic splitters, and the second fiber optic splitter is a 1 / 4 fiber optic splitter; the splitting ratio of the first fiber optic splitter is 1:20-99; the splitting ratio of the third fiber optic splitter, the fourth fiber optic splitter, the fifth fiber optic splitter, and the sixth fiber optic splitter are all 1:2-9.

[0016] The beneficial effects of this application are as follows: The hydrogen sensitive film of the present application is composited with a hydrogen-induced color-changing layer, a composite catalytic layer and an anti-oxidation layer, and has good catalytic selectivity and strong stability for hydrogen, thereby improving the response ability of hydrogen, which is beneficial to the improvement of the monitoring capacity and response rate of hydrogen; The sensor probe of the present application deposits a hydrogen sensitive film at the end of a single-mode optical fiber, thereby reducing the diffusion path of hydrogen molecules and improving the response capability to hydrogen, thereby reducing the power loss of the sensor probe and improving the response rate and monitoring capacity of the sensor probe; The multi-channel optical fiber hydrogen sensing system of the present application adopts a combination of a multi-channel optical path and a sensor probe, which reduces the cost of hydrogen concentration monitoring and has the advantages of long monitoring distance, high safety, large hydrogen monitoring capacity, and fast hydrogen response rate, which is conducive to the safe and rapid monitoring of hydrogen leaks in multiple locations in hydrogen-related places. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of a multi-channel optical fiber hydrogen sensing system; Figure 2 Schematic diagram of the structure of MoO3-PdPt-Pt composite film; Figure 3 This is the element test analysis diagram of the hydrogen sensitive film of this application; Figure 4 This is the response result diagram of the multi-channel optical fiber hydrogen sensing system under different hydrogen concentrations. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0019] In a first aspect, the present application provides a hydrogen sensitive film, which is a MoO3-PdPt-Pt composite film, comprising a MoO3 layer, a PdPt layer and a Pt layer stacked in sequence.

[0020] In the present application, the MoO3 layer is a hydrogen-induced color-changing layer, the PdPt layer is a composite catalytic layer, and the Pt layer is an antioxidant layer. The MoO3 film has an excellent hydrogen-induced color-changing effect, and can exist stably for a long time in the air with strong reliability; the Pd film has good selectivity for hydrogen, but Pd is prone to hydrogen embrittlement under high concentrations of hydrogen. The composite of Pd and Pt metal with good ductility can prepare a hydrogen catalyst with good selectivity and stability. The formed PdPt-Pt film layer acts as a catalyst, which can quickly convert hydrogen molecules into hydrogen atoms and has a strong hydrogen response capability; Pt has good antioxidant ability and can further enhance the reliability of the hydrogen-sensitive film as a surface protective layer; in the MoO3-PdPt-Pt composite film, after the MoO3 film reacts with hydrogen under the action of the PdPt film and the Pt film, it has a strong absorption of the light signal, thereby achieving high sensitivity and rapid response capability to hydrogen, and strong stability.

[0021] In some embodiments, the thickness of the MoO3 layer is 80-400 nm, the thickness of the PdPt layer is 10-40 nm, and the thickness of the Pt layer is 2-10 nm.

[0022] In some embodiments, in the PdPt layer, the Pt atomic content is 5-50%, and the Pd atomic content is 50-95%.

[0023] In a second aspect, the present application provides a method for preparing a hydrogen sensitive film, comprising the following steps: S1. Using MoO3 particles as raw materials, a MoO3 film is deposited on the surface of the substrate by vacuum evaporation; S2. Using Pd target and Pt target as raw materials, a PdPt composite film is deposited on the surface of the MoO3 film by magnetron sputtering; S3. Using Pt target as raw material, a Pt film is deposited on the surface of the PdPt composite film by magnetron sputtering. The obtained MoO3-PdPt-Pt composite film is a hydrogen sensitive film.

[0024] In the present application, the MoO3 particles in the hydrogen sensitive film have a lower melting point, and the thermal evaporation method is used for preparation with lower energy consumption, and the structure of the prepared hydrogen sensitive film is more stable.

[0025] In a third aspect, the present application provides a sensor probe comprising a hydrogen sensitive film, including a single-mode optical fiber and a hydrogen sensitive film deposited on the end of the single-mode optical fiber; the MoO3 layer of the hydrogen sensitive film is bonded to the end of the single-mode optical fiber.

[0026] In the present application, the sensor probe includes a hydrogen sensitive film. Since MoO3 in the hydrogen sensitive film reacts with hydrogen under the action of a catalyst, the absorption of infrared light is enhanced, thereby ensuring the sensitivity of the sensor probe. PdPt has a selective transmission function for hydrogen molecules, thereby enhancing the selectivity of the sensor probe. At the same time, the PdPt-Pt composite wave can control the reflectivity of the sensor probe to the signal light between 30% and 70%, thereby ensuring the sensitivity and response rate of the sensor probe. The Pt film layer has a surface catalytic function and has good antioxidant properties, thereby improving the stability and anti-interference of the probe, thereby improving the response rate. Overall, the use of a hydrogen sensitive film can reduce the diffusion path of hydrogen molecules and enhance the response rate and monitoring capacity of the probe.

[0027] In this application, the hydrogen sensitive film is deposited on the end of the single-mode optical fiber by physical vapor deposition. Specifically, the preparation method of the sensor probe is as follows: Using MoO3 particles as raw materials, MoO3 film is deposited on the end of single-mode optical fiber by vacuum resistance evaporation method; using Pd target and Pt target as raw materials, PdPt composite film is deposited on the surface of MoO3 film by magnetron sputtering method; using Pt target as raw material, Pt film is deposited on the surface of PdPt composite film by magnetron sputtering method. The obtained MoO3-PdPt-Pt composite film is hydrogen sensitive film.

[0028] In some embodiments, the diameter of the single-mode optical fiber is 80-100 μm; preferably, the single-mode optical fiber adopts the YOFC BI1015-B bend-insensitive single-mode optical fiber with a diameter of 80 μm.

[0029] In this embodiment, a bending-resistant optical fiber with a diameter of 80 μm is used to prepare the sensor probe. The end face of the thin-core optical fiber has a small heat conduction area, which can significantly reduce the power consumption of the sensor probe on the one hand, and on the other hand, is conducive to improving the anti-interference ability of the sensor probe / optical fiber hydrogen sensor, thereby improving the response rate and monitoring capacity of hydrogen.

[0030] In some embodiments, it also includes a protection tube sleeved on the single-mode optical fiber, and epoxy resin is filled between the single-mode optical fiber and the protection tube.

[0031] In this embodiment, the protective tube is a porous protective tube, and the single-mode optical fiber is sealed in the protective tube by epoxy resin; the raw material of the porous protective tube includes one or more of polycarbonate, acrylonitrile-butadiene-styrene ABS copolymer, and the cross-sectional shape of the porous protective tube includes one or more of rectangular, square, triangular or semicircular; the protective tube is sheathed at the free end of the single-mode optical fiber, that is, the part excluding the end where the hydrogen sensitive film is deposited.

[0032] In a fourth aspect, the present application provides a multi-channel optical fiber hydrogen sensing system, including an electrically connected light source, an optical fiber splitter, a sensor probe, a photodetector, and a signal processing display.

[0033] In this application, the light source is a 1550 nm coaxial pulsed laser light source. This type of light source has low transmission loss in optical fiber, ensuring the long-distance transmission capability of optical signals. The light source power range is 2-120 mW. The light source can also be replaced by a laser diode near the 1550 nm band.

[0034] In some embodiments, the fiber optic splitter includes a first fiber optic splitter 2, a second fiber optic splitter 4, a third fiber optic splitter 6, a fourth fiber optic splitter 10, a fifth fiber optic splitter 14, and a sixth fiber optic splitter 18; the photodetector includes a first photodetector 23, a second photodetector 25, a third photodetector 27, a fourth photodetector 29, and a fifth photodetector 31; the sensor probe includes a first sensor probe 9, a second sensor probe 13, a third sensor probe 17, and a fourth sensor probe 21; the input end of the first fiber optic splitter 2 is electrically connected to the light source, and the output end of the first fiber optic splitter 2 is divided into two paths and connected in parallel with the input end of the first photodetector 23 and the input end of the second fiber optic splitter 4; the output end of the second fiber optic splitter 4 is divided into four paths and connected in parallel with the input end of the third fiber optic splitter 6, the input end of the fourth fiber optic splitter 10, the input end of the fifth fiber optic splitter 14, and the input end of the sixth fiber optic splitter 18; The first output end of the third optical fiber splitter 6, the first output end of the fourth optical fiber splitter 10, the first output end of the fifth optical fiber splitter 14, and the first output end of the sixth optical fiber splitter 18 are correspondingly connected to the first sensor probe 9, the second sensor probe 13, the third sensor probe 17, and the fourth sensor probe 21; the second output end of the third optical fiber splitter 6, the second output end of the fourth optical fiber splitter 10, the second output end of the fifth optical fiber splitter 14, and the second output end of the sixth optical fiber splitter 18 are correspondingly connected to the input end of the second photodetector 25, the input end of the third photodetector 27, the input end of the fourth photodetector 29, and the input end of the fifth photodetector 31; the output ends of the first photodetector 23, the output ends of the second photodetector 25, the output ends of the third photodetector 27, the output ends of the fourth photodetector 29, and the output ends of the fifth photodetector 31 are electrically connected in parallel to the photodetectors and the signal processing display.

[0035] The multi-channel optical fiber hydrogen sensing system of the present application adopts a combination of hydrogen sensitive film, multi-channel optical path structure and reference signal, which is easy to prepare in batches, has good reliability and stability, and can realize accurate monitoring of hydrogen concentration. In addition, the transmission and conversion of optical signals adopt a coaxial pulse laser and a photodetector with a central wavelength of 1550 nm, which has the advantages of low cost, long monitoring distance, safety and reliability, and is suitable for monitoring and alarming hydrogen concentration during hydrogen production and use. It effectively overcomes the disadvantage that traditional light intensity modulation optical fiber hydrogen sensors are difficult to network at multiple points. The optical fiber hydrogen monitoring system of the present invention adopts a multi-channel optical path, which can connect multiple probes for detection, and can be placed in multiple hydrogen-related scenes to simultaneously perform hydrogen leakage detection, thereby reducing the monitoring cost of hydrogen concentration in hydrogen-related scenes.

[0036] In some embodiments, the first fiber optic splitter 2, the third fiber optic splitter 6, the fourth fiber optic splitter 10, the fifth fiber optic splitter 14, and the sixth fiber optic splitter 18 are all 1 / 2 fiber optic splitters, and the second fiber optic splitter 4 is a 1 / 4 fiber optic splitter; the splitting ratio of the first fiber optic splitter 2, i.e., the front fiber optic splitter, is 1:20-99; the splitting ratios of the third fiber optic splitter 6, the fourth fiber optic splitter 10, the fifth fiber optic splitter 14, and the sixth fiber optic splitter 18 are all 1:2-9.

[0037] In the present application, the first fiber optic splitter 2 is used as a front fiber optic splitter, which is a 1 / 2 fiber optic splitter. The splitting ratio at both ends of the front fiber optic splitter is between 1:99-1:20. The light emitted by the 1550 nm coaxial pulse laser light source is input through one end of the single end of the front fiber optic splitter, and is divided into two parts by the front fiber optic splitter and output to the front fiber optic splitter. The optical signal at the end with low power is received by the photodetector as an electrical signal as a reference signal; the optical signal at the end with high power enters the fourth fiber optic splitter 10, i.e., a 1 / 4 equal-split splitter. The 1 / 4 equal-split optical splitter divides most of the light input from the front fiber optic splitter into four equal parts and then enters the four rear-end 1 / 2 optical splitters (i.e., the third fiber optic splitter 6, the fourth optical splitter 7, and the fourth optical splitter 8). The main channel light splitting ratio at both ends of the optical fiber splitter 10, the fifth optical fiber splitter 14, and the sixth optical fiber splitter 18 is 20:80, and the optical signal enters the sensing probe through the single end of the rear end 1 / 2 optical splitter. The optical signal reflected by the sensing probe enters the single end of the rear end 1 / 2 optical splitter again, and then outputs through the channel with smaller double-end splitting ratio and enters the photoelectric detector, and is converted into a sensing signal. The splitting ratio at both ends of the rear end 1 / 2 optical split is between 1:2-9; the hydrogen concentration is calculated and displayed through the signal transmission and processing system.

[0038] The multi-channel optical fiber hydrogen sensing system of the present invention can reduce the cost of the hydrogen sensing system and improve the system performance; depositing a nano-composite film on a thin-core bend-insensitive optical fiber can significantly reduce the power loss of a single probe on the one hand, and improve the response rate of the probe on the other hand; at the same time, combining a multi-channel optical path design with a photodetector for optical signal conversion can significantly improve the monitoring capacity of the sensing system while reducing the system cost; improving the detection capacity and response rate of the optical fiber hydrogen sensing system, thereby achieving safe, reliable and rapid monitoring of hydrogen leaks at multiple locations in hydrogen-related places.

[0039] The present solution is further described below through specific embodiments.

[0040] Example 1 A hydrogen sensitive film is a MoO3-PdPt-Pt composite film, comprising a MoO3 layer, a PdPt layer and a Pt layer stacked in sequence; wherein the thickness of the MoO3 layer is 200nm, the thickness of the PdPt layer is 27nm, and the thickness of the Pt layer is 8nm; in the PdPt layer, the Pt atomic content is 45%, and the Pd atomic content is 67%.

[0041] The method for preparing a hydrogen sensitive film comprises the following steps: S1. Place MoO3 particles in a molybdenum boat of a vacuum coating machine, then place an optical fiber on top of the molybdenum boat with the end face of the optical fiber facing downward, evacuate the molybdenum boat and heat it to evaporate MoO3 onto the end face of the bend-insensitive single-mode optical fiber to obtain a MoO3 layer, and transfer the sample to the cavity of a magnetron sputtering coating machine; S2. Pd target and Pt target are installed at two target positions in the magnetron sputtering equipment, and after the magnetron sputtering is evacuated, argon gas is filled into the chamber, and voltage is applied to ionize the argon gas into argon ions, which bombard the Pd target and the Pt target at the same time to obtain a PdPt layer on the surface of the MoO3 layer; S3. Stop bombarding the Pd target in the magnetron sputtering device and only bombard the Pt target to obtain a Pt layer, that is, a hydrogen sensitive film.

[0042] Example 2 A sensor probe including a hydrogen sensitive film comprises a single-mode optical fiber, a hydrogen sensitive film deposited on the end of the single-mode optical fiber, and a protective tube sleeved on the single-mode optical fiber; wherein epoxy resin is filled between the single-mode optical fiber and the protective tube, the MoO3 layer of the hydrogen sensitive film is bonded to the end of the single-mode optical fiber, and the diameter of the single-mode optical fiber is 80-100 μm.

[0043] The preparation method of the sensor probe including the hydrogen sensitive film comprises the following steps: MoO3 particles were placed in a molybdenum boat of a vacuum coating machine, and then a 80μm diameter Changfei BI1015-B bend-insensitive single-mode optical fiber with a flat and cleaned end face was placed on top of the molybdenum boat, with the end face of the optical fiber facing downward. After the molybdenum boat was evacuated to a vacuum degree, the MoO3 was evaporated onto the end face of the bend-insensitive single-mode optical fiber to obtain a MoO3 layer, and the sample was transferred to the cavity of a magnetron sputtering coating machine; Pd target and Pt target are installed at two target positions in the magnetron sputtering equipment respectively. After the magnetron sputtering is evacuated, argon gas is filled into the chamber, and voltage is applied to ionize the argon gas into argon ions, which bombard the Pd target and Pt target at the same time to obtain a PdPt layer on the surface of the MoO3 layer. Stop bombarding the Pd target in the magnetron sputtering device and only bombard the Pt target to obtain a Pt layer, that is, a sensor probe including a hydrogen sensitive film; The protection tube is sleeved on the free end of the sensor probe containing the hydrogen sensitive film, and epoxy resin is filled between the protection tube and the sensor probe containing the hydrogen sensitive film for sealing.

[0044] Example 3 A multi-channel optical fiber hydrogen sensing system comprises an electrically connected light source, an optical fiber splitter, a sensor probe, a photodetector and a signal processing display; the light source adopts a coaxial pulse laser light source with a central wavelength of 1550 nm, which mainly provides an optical signal for the sensing system, and the light source power ranges from 2 to 120 mW; the optical fiber splitter comprises a first optical fiber splitter 2, a second optical fiber splitter 4, a third optical fiber splitter 6, a fourth optical fiber splitter 10, a fifth optical fiber splitter 14, and a sixth optical fiber splitter 18; the photodetector comprises a first photodetector 23, a second photodetector 25, a third photodetector 27, a fourth photodetector 29, and a fifth photodetector 31; the sensor probe comprises a first sensor probe 9, a second sensor probe 13, a third sensor probe 17, and a fourth sensor probe 21; the input end of the first optical fiber splitter 2 is electrically connected to the light source, and the single-end and double-end power input ratio of the first optical fiber splitter 2 is between 0.03 and 0.06. 1; the output end of the first optical fiber splitter 2 is divided into two paths and connected in parallel with the input end of the first photodetector 23 and the input end of the second optical fiber splitter 4, wherein the end with lower output energy of the first optical fiber splitter 2 is connected to the first photodetector 23, and the end with higher output energy is connected to the single end of the second optical fiber splitter 4; the output end of the second optical fiber splitter 4 is divided into four paths and connected in parallel with the input end of the third optical fiber splitter 6, the input end of the fourth optical fiber splitter 10, the input end of the fifth optical fiber splitter 14, and the input end of the sixth optical fiber splitter 18; the first output end of the third optical fiber splitter 6, the first output end of the fourth optical fiber splitter 10, the first output end of the The first output end of the fifth optical fiber splitter 14 and the first output end of the sixth optical fiber splitter 18 are correspondingly connected to the first sensor probe 9, the second sensor probe 13, the third sensor probe 17, and the fourth sensor probe 21; the second output end of the third optical fiber splitter 6, the second output end of the fourth optical fiber splitter 10, the second output end of the fifth optical fiber splitter 14, and the second output end of the sixth optical fiber splitter 18 are correspondingly connected to the input end of the second photodetector 25, the input end of the third photodetector 27, the input end of the fourth photodetector 29, and the input end of the fifth photodetector 31; the output end of the first photodetector 23, the second photodetector 27, the fourth photodetector 29, and the fifth photodetector 31 The output end of the device 25, the output end of the third photodetector 27, the output end of the fourth photodetector 29, and the output end of the fifth photodetector 31 are electrically connected in parallel to the photodetectors and the signal processing display; the first optical fiber splitter 2, the third optical fiber splitter 6, the fourth optical fiber splitter 10, the fifth optical fiber splitter 14, and the sixth optical fiber splitter 18 are all 1 / 2 optical fiber splitters, and the second optical fiber splitter 4 is a 1 / 4 optical fiber splitter; the splitting ratio of the first optical fiber splitter 2 is 1:20-99; the splitting ratio of the third optical fiber splitter 6, the fourth optical fiber splitter 10, the fifth optical fiber splitter 14, and the sixth optical fiber splitter 18 are all 1:2-9.

[0045] The optical path conversion route of the multi-channel optical fiber hydrogen sensing system is as follows: the optical signal emitted by the 1550 nm coaxial pulse laser light source 1 is input through the end with a higher splitting ratio in the double ends of the first optical fiber splitter 2, and the main optical signal 3 is divided into four paths through the 1 / 4 equal-splitting optical fiber splitter, i.e., the second optical fiber splitter 4, and reaches the end with a higher splitting ratio in the double ends of the rear-end 1 / 2 optical splitter, i.e., the third optical fiber splitter 6, the fourth optical fiber splitter 10, the fifth optical fiber splitter 14, and the sixth optical fiber splitter 18; the optical signals 7, 11, 15, and 19 passing through the single end of the rear-end 1 / 2 optical splitter reach the corresponding sensor probes, i.e., the first sensor probe 9, the second sensor probe 13, the third sensor probe 17, and the fourth sensor probe 21, and are transmitted to the hydrogen sensitive film of each sensor probe, and the hydrogen sensitive film reflects a part of the light emitted by the light source back, and the reflected light 8, 12, 16, and 20 of each path passes through the third optical fiber splitter 6, the fourth optical fiber splitter 10, the fifth optical fiber splitter 14, and the sixth optical fiber splitter 18, respectively. The splitter 10, the fifth optical fiber splitter 14, and the sixth optical fiber splitter 18 form optical signals 24, 26, 28, and 30 respectively and are converted into electrical signals through the second photodetector 25, the third photodetector 27, the fourth photodetector 29, and the fifth photodetector 31, and then transmitted to the signal processing circuit 32; the other optical signal 22 passes through the first photodetector 23, and the optical signal is converted into an electrical signal and then output to reach the signal processing display 32; since the reflectivity of the hydrogen sensitive film is affected by the hydrogen in the environment, the reflectivity of the hydrogen sensitive film will change under different hydrogen concentrations, thereby changing the light intensity reaching the probe, and the voltage value will change accordingly after the light intensity changes, and there is a certain corresponding relationship between the voltage value of the photoelectric conversion and the hydrogen concentration. After the sensor is calibrated, the hydrogen concentration in the environment can be calculated based on the measured voltage value.

[0046] Figure 3 Shown is an element test analysis diagram of the hydrogen sensitive film of the present application. Figure 4 This is the response of Example 4 under different hydrogen concentrations. In a laboratory environment, the lowest hydrogen concentration that can be measured is 20 ppm. As can be seen from the figure, the optical fiber hydrogen sensing system based on MoO3-PdPt-Pt composite film has a large change amount and a fast response speed to the change of hydrogen concentration, which can realize accurate monitoring and alarm in the process of hydrogen production and transportation, and can realize multi-point or multi-region measurement and early warning.

[0047] The multi-channel optical fiber hydrogen sensing system provided by the present invention adopts a small-diameter anti-bending single-mode optical fiber as the transmission medium in the optical path part, which can avoid the existing optical fiber hydrogen sensor being easily affected by the bending of the optical path; the probe part adopts MoO3-PdPt-Pt nanocomposite film as the hydrogen sensitive material, which ensures the stability and fast response capability of the sensitive film; the coaxial pulse laser light source with a central wavelength of 1550 nm is used as the sensing light source, and the photodetector is used as the photosensitive element, which can avoid the use of a high-cost tunable laser light source and a fiber grating demodulation module, greatly reducing the system cost. The test results show that the multi-channel optical fiber hydrogen sensing system provided by the present invention can quickly and accurately realize the alarm function within a large hydrogen concentration range. The multi-channel optical fiber hydrogen sensing system based on MoO3-PdPt-Pt nanocomposite film has a wide range of application prospects in hydrogen storage and transportation facilities such as hydrogen production plants, hydrogen refueling stations, hydrogen energy vehicles, and hydrogen energy power generation facilities.

[0048] The above are only preferred specific implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A hydrogen sensitive film, characterized in that: It is a MoO3-PdPt-Pt composite film, comprising a MoO3 layer (34), a PdPt layer (35) and a Pt layer (36) stacked in sequence.

2. The hydrogen sensitive film according to claim 1, characterized in that: The thickness of the MoO3 layer is 80-400nm, the thickness of the PdPt layer is 10-40nm, and the thickness of the Pt layer is 2-10nm.

3. The hydrogen sensitive film according to claim 1, characterized in that: In the PdPt layer, the Pt atomic content is 5-50%, and the Pd atomic content is 50-95%.

4. A method for preparing a hydrogen sensitive film according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Using MoO3 particles as raw materials, a MoO3 layer is deposited on the surface of the substrate by vacuum evaporation method; S2. Using Pd target and Pt target as raw materials, a PdPt layer is deposited on the surface of the MoO3 layer by magnetron sputtering; S3. Using a Pt target as a raw material, a Pt layer is deposited on the surface of the PdPt layer by a magnetron sputtering method, and the obtained MoO3-PdPt-Pt composite film is the hydrogen sensitive film.

5. A sensor probe comprising the hydrogen sensitive film according to any one of claims 1 to 3, characterized in that: It comprises a single-mode optical fiber (33) and a hydrogen-sensitive film deposited on the end of the single-mode optical fiber (33); The MoO3 layer of the hydrogen sensitive film is bonded to the end of the single-mode optical fiber (33).

6. The sensor probe according to claim 5, characterized in that: The diameter of the single-mode optical fiber is 80-100 μm.

7. The sensor probe according to claim 5, characterized in that: It also includes a protective tube (38) sleeved on the single-mode optical fiber (33), and epoxy resin is filled between the single-mode optical fiber and the protective tube.

8. A multi-channel optical fiber hydrogen sensing system, characterized in that: The invention comprises an electrically connected light source, an optical fiber splitter, a sensor probe as claimed in claim 5 or any one of claims 6 to 7, a photoelectric detector and a signal processing display.

9. The multi-channel optical fiber hydrogen sensing system according to claim 8, characterized in that: The optical fiber splitter comprises a first optical fiber splitter (2), a second optical fiber splitter (4), a third optical fiber splitter (6), a fourth optical fiber splitter (10), a fifth optical fiber splitter (14), and a sixth optical fiber splitter (18); the photoelectric detector comprises a first photoelectric detector (23), a second photoelectric detector (25), a third photoelectric detector (27), a fourth photoelectric detector (29), and a fifth photoelectric detector (31); the sensor probe comprises a first sensor probe (9), a second sensor probe (13), a third sensor probe (17), and a fourth sensor probe (21); The input end of the first optical fiber splitter (2) is electrically connected to the light source, and the output end of the first optical fiber splitter (2) is divided into two paths and connected in parallel to the input end of the first photodetector (23) and the input end of the second optical fiber splitter (4); The output end of the second optical fiber splitter (4) is divided into four paths and connected in parallel with the input end of the third optical fiber splitter (6), the input end of the fourth optical fiber splitter (10), the input end of the fifth optical fiber splitter (14), and the input end of the sixth optical fiber splitter (18); The first output end of the third optical fiber splitter (6), the first output end of the fourth optical fiber splitter (10), the first output end of the fifth optical fiber splitter (14), and the first output end of the sixth optical fiber splitter (18) are correspondingly connected to the first sensor probe (9), the second sensor probe (13), the third sensor probe (17), and the fourth sensor probe (21); the second output end of the third optical fiber splitter (6), the second output end of the fourth optical fiber splitter (10), the second output end of the fifth optical fiber splitter (14), and the second output end of the sixth optical fiber splitter (18) are correspondingly connected to the input end of the second photoelectric detector (25), the input end of the third photoelectric detector (27), the input end of the fourth photoelectric detector (29), and the input end of the fifth photoelectric detector (31); The output end of the first photodetector (23), the output end of the second photodetector (25), the output end of the third photodetector (27), the output end of the fourth photodetector (29), and the output end of the fifth photodetector (31) are electrically connected in parallel to the photodetectors and the signal processing display.

10. The multi-channel optical fiber hydrogen sensing system according to claim 9, characterized in that: The first optical fiber splitter (2), the third optical fiber splitter (6), the fourth optical fiber splitter (10), the fifth optical fiber splitter (14), and the sixth optical fiber splitter (18) are all 1 / 2 optical fiber splitters, and the second optical fiber splitter (4) is a 1 / 4 optical fiber splitter; the splitting ratio of the first optical fiber splitter (2) is 1:20-99; the splitting ratio of the third optical fiber splitter (6), the fourth optical fiber splitter (10), the fifth optical fiber splitter (14), and the sixth optical fiber splitter (18) are all 1:2-9.

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