A micro-channel reactor for photocatalytic decomposition of water to produce hydrogen by light focusing on a tapered tip of an optical fiber, a preparation method thereof, and application thereof

Abstract

The application discloses a micro-channel reactor for photocatalytic decomposition of water to produce hydrogen by light focusing of a fiber taper tip, a preparation method of the micro-channel reactor and application of the micro-channel reactor. The reaction main channel of the micro-channel reactor is respectively connected with a solution injection channel and a solution outflow channel, and the reaction main channel is connected with a laser through a fiber. The end of the fiber is subjected to a heat stretching tapering treatment. The fiber core guides laser emitted by the laser to the end of the fiber through the fiber end taper tip. The end of the fiber is loaded with a photocatalyst. The micro-channel reactor is movably arranged on a metallographic microscope loading table. The application uses the fiber as a catalyst carrier, greatly reduces the amount of the photocatalyst, uses the laser as a light source, improves light intensity through the light focusing of the fiber taper tip structure, and shortens the energy transmission distance of light to the surface of the catalyst, so that the photocatalytic performance is improved. The transparent micro-channel reactor is made of PDMS, and the photocatalytic reaction process is observed in real time and in situ through the metallographic microscope, so that the photocatalytic performance can be measured.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic water splitting for hydrogen production technology, specifically to a microchannel reactor for photocatalytic water splitting for hydrogen production using an optical fiber cone tip, its preparation method, and its application. Background Technology

[0002] Photocatalysis, as a green and clean technology that converts light energy into chemical energy, has significant application prospects in both the energy and environmental fields. Photocatalysis technology is based on the catalytic action of semiconductor-based catalysts. The semiconductor material absorbs photon energy, generating photogenerated carriers (electrons and holes). These photogenerated carriers then move to the catalyst surface, where electrons and holes react with water or organic pollutants in redox reactions, achieving the conversion of light energy into hydrogen chemical energy or the degradation of organic pollutants. While the technology for photodegrading organic pollutants is relatively mature, photocatalytic water splitting for hydrogen production has not yet reached the economic standard for large-scale application. The main factors limiting photocatalytic water splitting for hydrogen production technology include the performance of the photocatalyst materials, reaction conditions, and the structural design of the device.

[0003] Current research on improving photocatalytic reaction devices focuses on photocatalytic microreactors, which combine microchannel structures with photocatalysts to improve mass transfer conditions and thus increase the reaction rate. Classic photocatalytic microreactor devices include rectangular cavity planar microreactors and serpentine channel microreactors. Many researchers are also dedicated to applying photofluidic methods to photocatalytic reactions. Photofluidic methods refer to the combination of photonics and microfluidics. By improving mass transport using microreactors and controlling the optical transport conditions of the reaction to achieve efficient coupling and utilization of the catalyst and photons, photocatalytic reaction performance can be further improved, achieving breakthroughs in efficiency. Chinese patent application CN114130323A discloses an optical fiber microchannel reactor, which introduces an optical fiber as a light source and a catalyst loading device into the microchannel reactor, achieving effective concentration of light energy on the photocatalyst and further improving photocatalytic reaction performance.

[0004] The aforementioned patent application discloses a photocatalytic microreactor based on optical fiber evanescent waves. Its main application is the photocatalytic degradation of organic pollutants, with the effectiveness of organic pollutant treatment achieved by detecting the recovered reaction solution. However, in the photocatalytic water splitting for hydrogen production, the efficiency remains low. Besides limiting factors such as catalyst-photon coupling efficiency and mass transfer conditions, photon density itself is a significant factor limiting efficiency. Concentrated photocatalysis has proven to be an effective way to improve photocatalytic efficiency. Furthermore, collecting and detecting the hydrogen produced is difficult, and the collection process may introduce errors. In addition to detecting hydrogen production, dynamic observation of the photocatalytic micro-reaction process helps to evaluate its photocatalytic performance. It also allows for the exploration of reaction mechanisms on the catalyst surface, studying the nucleation rate of hydrogen bubbles under different input wavelengths, and the relationship between nucleation size and interface detachment size and rate, potentially leading to breakthroughs in the fundamental theory of photocatalysis at the micro- and nano-scale. However, the microchannel device in the aforementioned patent application has an opaque reaction region and lacks a dedicated experimental observation device, making real-time and effective dynamic observation of the reaction difficult, which is inconvenient for photocatalytic water splitting for hydrogen production. Summary of the Invention

[0005] To overcome the shortcomings of the existing technology, the present invention aims to provide a microchannel reactor for photocatalytic water splitting to produce hydrogen, its preparation method, and its application. The main reaction channel of the microchannel reactor is connected to a laser via an optical fiber. The optical fiber serves as the carrier for the photocatalyst, and the microchannel reactor itself reduces the amount of photocatalyst required. During the preparation of the microchannel reactor, the end of the optical fiber is tapered, and the tip is loaded with the photocatalyst, significantly reducing light loss during propagation and improving photocatalytic performance. The transparent microchannel chip fabricated using PDMS allows for real-time observation of the photocatalytic reaction process using a metallographic microscope, facilitating the evaluation of photocatalytic performance. This invention combines optical fiber guidance with a microchannel reactor, enabling control over both the light field and fluid mass transfer, thereby improving photocatalytic performance.

[0006] To achieve the above objectives, the technical means employed in this invention are as follows:

[0007] A microchannel reactor for photocatalytic water splitting to produce hydrogen using an optical fiber tapered tip includes a main reaction channel 41, which is connected to a solution injection channel 42 and a solution outflow channel 43. The main reaction channel 41 is also connected to a laser 1 via an optical fiber 3. The end of the optical fiber 3 is subjected to a thermally stretched tapered treatment. The core of the optical fiber 3 guides the laser emitted by the laser 1 through the tapered tip of the optical fiber. The tapered tip of the optical fiber 3 is loaded with a photocatalyst.

[0008] The optical fiber 3 is connected to the laser 1 via optical fiber coupling, and the part of the optical fiber 3 entering the microchannel reactor 4 is sealed.

[0009] The microchannel reactor 4 is made of a curable polymer material, including PDMS (polydimethylsiloxane), epoxy resin, or polyurethane.

[0010] The inner diameter of the main reaction channel 41 of the microchannel reactor 4 is 250μm–400μm, the inner diameter of the solution injection channel 42 of the microchannel reactor 4 is 0.4mm–1mm, and the inner diameter of the solution outflow channel 43 of the microchannel reactor 4 is 0.4mm–1mm.

[0011] A method for preparing a microchannel reactor for photocatalytic water splitting to produce hydrogen using an optical fiber cone tip for focusing light is described below:

[0012] Step 1. Material preparation: Mix the prepolymer of the curing polymer and the curing agent at a mass ratio of 8:1 to 10:1 until homogeneous, vacuum degas for 20-30 minutes to eliminate air bubbles, and let stand at room temperature for 1-2 hours.

[0013] Step 2. Substrate preparation: Use a spin coater to spin coat a layer of curable polymer onto a glass slide at a speed of 500-900 r / min to serve as a substrate. Heat and cure at 60-80℃ for 20-30 min. The thickness of the substrate is 1-10 mm.

[0014] Step 3. Fabrication of tapered optical fiber: Take a section of optical fiber about 50-80cm in length, clamp the optical fiber from both ends, peel off the coating layer in the middle 3-5cm of the optical fiber, burn the area where the coating layer was peeled off, and after burning to a molten state, fix one end and pull the other end quickly. The optical fiber will break at the burned point. The burned part of the optical fiber at the pulled end will be drawn into a tapered structure. Load the tapered part with a photocatalyst by physical impregnation.

[0015] Step 4. Preparation of each channel: On the substrate prepared in Step 2, according to the structure of the microchannel reactor 4, place the mold of the main reaction channel 41, the mold of the solution injection channel 42, the mold of the solution outflow channel 43, and the tapered optical fiber 3, pour on the curable polymer, heat and cure for 20-30 minutes, pull out the mold, and then heat and cure at 60-80℃ for 20-30 minutes to form the channel;

[0016] Step 5. Channel connection and sealing: Use a hole punch to make small holes so that the main reaction channel 41 is connected to the solution injection channel 42 and the solution outflow channel 43 respectively. Then cut two pieces of cured polymer film with a thickness of 1-10mm. Apply a layer of uncured polymer to one side and cover the outside of the small hole. Heat and cure to seal the outside of the small hole.

[0017] The physical impregnation described in step 3 uses a photocatalyst. After ultrasonic homogenization for 20-40 minutes, the tapered fiber tip is immersed in the photocatalyst for 30-60 seconds and then air-dried for 30-60 seconds. This process is repeated 3-5 times.

[0018] The photocatalyst is a metal sulfide semiconductor photocatalyst or a metal oxide semiconductor photocatalyst; the metal sulfide semiconductor photocatalyst includes cadmium sulfide and zinc sulfide; the metal oxide semiconductor photocatalyst includes zinc oxide and titanium dioxide.

[0019] The curable polymer is PDMS, epoxy resin or polyurethane; the curing agent is methyltriethoxysilane or methyltripropoxysilane.

[0020] A microchannel photocatalytic water splitting hydrogen production in-situ observation system based on a microchannel reactor with fiber optic cone-tip focusing includes a microchannel reactor 4. The microchannel reactor 4 has a main reaction channel 41, which is connected to a solution injection pump 2 via a solution injection channel 42, and to a liquid inflow channel of a gas-liquid collection sample bottle 5 via a solution outflow channel 43. It is also connected to a laser 1 via an optical fiber 3. The end of the optical fiber 3 is thermally stretched and tapered, and the fiber core guides the laser light through the tapered tip. The tapered tip is loaded with a photocatalyst. The gas-liquid collection sample bottle 5 is connected to a gas chromatograph 6 via a gas delivery pipe. The microchannel reactor 4 is movably placed on the stage of a metallurgical microscope 7.

[0021] The optical fiber 3 is connected to the laser 1 via optical fiber coupling, and the part of the optical fiber 3 entering the microchannel reactor 4 is sealed; the laser 1 is a supercontinuum laser, and the wavelength of the light emitted by the laser 1 is in the ultraviolet and visible light bands.

[0022] The solution is a sacrificial reagent used in the photocatalytic reaction or pure water; the sacrificial reagent includes methanol, lactic acid, triethanolamine, sodium sulfite or sodium sulfide.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. The microchannel reactor of this invention uses optical fiber 3 as the carrier of the photocatalyst and microchannel reactor 4 as the reactor. The main reaction channel is connected to a laser via optical fiber. The end of optical fiber 3 is thermally stretched and tapered. The core of optical fiber 3 guides the laser emitted by laser 1 through the tapered tip of the fiber end. The tapered tip of optical fiber 3 is loaded with photocatalyst. The tapered structure can focus the light, increase the light intensity, and reduce the amount of photocatalyst used in the photocatalytic reaction. Using laser 1 as the light source reduces energy consumption compared to traditional light sources. Light enters the fiber core from the light source and propagates to the catalyst loaded on the fiber, reducing light loss during propagation and without reducing the effectiveness of the photocatalytic reaction.

[0025] 2. When preparing the microchannel reactor, the end of the optical fiber is tapered and the tip is loaded with a photocatalyst, which greatly reduces the amount of photocatalyst used. The catalyst coated on the optical fiber can also directly contact the transmitted light, shortening the energy transmission distance from the light to the catalyst surface, greatly reducing the loss of light during propagation, and helping to improve the photocatalytic performance.

[0026] 3. Transparent microchannel chips made from prepolymers of cured polymers (such as PDMS) can be used to observe the photocatalytic reaction process in real time in situ using a metallographic microscope, which helps to measure photocatalytic performance.

[0027] In summary, this invention has the advantages of simple structure, low light loss, energy saving, and good photocatalytic performance. Attached Figure Description

[0028] Figure 1 This is an overall schematic diagram of the photocatalytic water splitting hydrogen production reaction system according to an embodiment of the present invention;

[0029] Figure 2(a) is a schematic diagram of the preparation of the microchannel reactor according to an embodiment of the present invention;

[0030] Figure 2(b) is a schematic diagram of the microchannel reactor mounted under a metallographic microscope at the beginning of the experiment;

[0031] Figure 3 The following are in-situ observation results of an embodiment of the present invention: a is an enlarged view of the tapered tip of the tapered optical fiber in the reaction area observed by a metallographic microscope when the laser is not turned on; b is an observation of the generation of hydrogen bubbles in the reaction area when the reaction begins after the laser is turned on.

[0032] Figure 4 This is an enlarged structural view of a microchannel reactor for photocatalytic water splitting to produce hydrogen, which uses an optical fiber cone tip for focusing light, according to the present invention.

[0033] In the figure: 1-Laser; 2-Injection pump; 3-Fiber optic cable; 4-Microchannel reactor; 41-Main reaction channel; 42-Solution injection channel; 43-Solution effluent channel; 5-Gas-liquid collection sample bottle; 6-Gas chromatograph; 7-Metallic microscope. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the accompanying drawings.

[0035] See Figure 1 Figure 2 shows a microchannel reactor for photocatalytic water splitting to produce hydrogen using an optical fiber tapered tip. The reactor includes a main reaction channel 41, which is connected to a solution injection channel 42 and a solution outflow channel 43. The main reaction channel 41 is also connected to a laser 1 via an optical fiber 3. The end of the optical fiber 3 is subjected to a thermally stretched tapered treatment. The core of the optical fiber 3 guides the laser emitted by the laser 1 through the tapered tip of the optical fiber. The tapered tip of the optical fiber 3 is loaded with a photocatalyst.

[0036] The optical fiber 3 is connected to the laser 1 via optical fiber coupling, and the part of the optical fiber 3 entering the microchannel reactor 4 is sealed.

[0037] The microchannel reactor 4 uses a cured polymer material, including PDMS (polydimethylsiloxane).

[0038] The inner diameter of the main reaction channel 41 of the microchannel reactor 4 is 250μm–400μm, the inner diameter of the solution injection channel 42 of the microchannel reactor 4 is 0.4mm–1mm, and the inner diameter of the solution outflow channel 43 of the microchannel reactor 4 is 0.4mm–1mm.

[0039] A method for preparing a microchannel reactor for photocatalytic water splitting to produce hydrogen using an optical fiber cone tip, as shown in Figure 2. Figure 3 The specific steps are as follows:

[0040] Step 1. Material preparation: Mix the prepolymer of the curing polymer and the curing agent at a mass ratio of 8:1 to 10:1 until homogeneous, vacuum degas for 20-30 minutes to eliminate air bubbles, and let stand at room temperature for 1-2 hours.

[0041] Step 2. Substrate preparation: Use a spin coater to spin coat a layer of curable polymer onto a glass slide at a speed of 500-900 r / min to serve as a substrate. Heat and cure at 60-80℃ for 20-30 min. The thickness of the substrate is 1-10 mm.

[0042] Step 3. Fabrication of tapered optical fiber: Take a 50-80cm length of optical fiber, clamp the fiber from both ends, peel off the coating layer in the middle 3-5cm of the fiber, ignite the area where the coating layer has been removed until it melts, keep one end still, and quickly pull the other end until the fiber breaks at the ignition point. The ignition point of the pulled end of the fiber is drawn into a tapered structure. Apply a photocatalyst to the tapered part, sonicate it evenly for 20-40 minutes, then immerse the tapered fiber tip in the photocatalyst for 30-60 seconds and air dry for 30-60 seconds. Repeat this process 3-5 times to load the photocatalyst.

[0043] Step 4. Preparation of each channel: On the substrate prepared in step 2, according to the structure of the microchannel reactor 4, place the mold of the main reaction channel 41, the mold of the solution injection channel 42, the mold of the solution outflow channel 43, and the tapered optical fiber 3, pour on the curable polymer, heat and cure for 20-30 minutes, then pull out the mold and heat and cure again at 60-80℃ for 20-30 minutes to form each channel;

[0044] Step 5. Channel connection and sealing: Use a hole punch to make small holes so that the main reaction channel 41 is connected to the solution injection channel 42 and the solution outflow channel 43 respectively. Then cut two pieces of cured polymer film with a thickness of 1-10mm. Apply a layer of uncured polymer to one side and cover the outside of the small hole. Heat and cure to seal the outside of the small hole.

[0045] The cured polymer includes PDMS, epoxy resin, or polyurethane.

[0046] The curing agent includes methyltriethoxysilane or methyltripropoxysilane.

[0047] The photocatalyst is a metal sulfide semiconductor photocatalyst or a metal oxide semiconductor photocatalyst; the metal sulfide semiconductor photocatalyst includes cadmium sulfide and zinc sulfide; the metal oxide semiconductor photocatalyst includes zinc oxide and titanium dioxide.

[0048] A microchannel photocatalytic water splitting hydrogen production in-situ observation system based on a microchannel reactor with fiber optic cone-tip focusing includes a microchannel reactor 4. The microchannel reactor 4 has a main reaction channel 41, which is connected to a solution injection pump 2 via a solution injection channel 42, and to a liquid inflow channel of a gas-liquid collection sample bottle 5 via a solution outflow channel 43. It is also connected to a laser 1 via an optical fiber 3. The end of the optical fiber 3 is thermally stretched and tapered, and the fiber core guides the laser light through the tapered tip. The tapered tip is loaded with a photocatalyst. The gas-liquid collection sample bottle 5 is connected to a gas chromatograph 6 via a gas delivery pipe. The microchannel reactor 4 is movably placed on the stage of a metallurgical microscope 7.

[0049] The optical fiber 3 is connected to the laser 1 via optical fiber coupling, and the part of the optical fiber 3 entering the microchannel reactor 4 is sealed; the laser 1 is a supercontinuum laser, and the wavelength of the light emitted by the laser 1 is in the ultraviolet and visible light bands.

[0050] The solution injected by the solution injection pump 2 is a sacrificial reagent used in the photocatalytic reaction or pure water; the sacrificial reagent includes methanol, lactic acid, triethanolamine, sodium sulfite or sodium sulfide.

[0051] Example 1

[0052] The reaction process of the photocatalytic water splitting hydrogen production system is observed and recorded in situ by a metallographic microscope using a computer. The hydrogen produced by the reaction and the injection solution are discharged into the sample vial through the solution outlet channel. The hydrogen in the sample vial is then sent to a gas chromatograph to detect the hydrogen production.

[0053] In this embodiment of the application, the laser is a supercontinuum laser that can emit a continuous spectrum of 300-2400nm. The light field transmitted to the tip of the fiber optic cone can be controlled by adjusting the power of the laser.

[0054] Example 2

[0055] The microchannel reactor 4 was prepared using a prepolymer of PDMS, which is transparent in shape. The reaction process was observed and recorded in situ above the microchannel reactor 4 using a metallographic microscope 7.

[0056] In this embodiment of the invention, the photocatalyst can be loaded onto a tapered optical fiber by physical impregnation. Using zinc-cadmium sulfur (CCS) as the photocatalyst, the CCS photocatalyst suspension is ultrasonically homogenized for 20-40 minutes. The tip of the tapered optical fiber is then immersed in the CCS photocatalyst suspension for 30-60 seconds, followed by air drying for 30-60 seconds. This process is repeated 3-5 times. The physical impregnation method can be replaced by a hydrothermal method.

[0057] like Figure 3 As shown, the metallurgical microscope 7 can observe the condition of the optical fiber 3 within the reaction area of ​​the microchannel reactor 4. During the insertion of the optical fiber 3 into the microchannel reactor 4, the metallurgical microscope 7 can also be used to observe the condition of the optical fiber 3 to prevent situations such as breakage of the tip of the optical fiber 3 due to tilted insertion angle. Figure 3 (a) An observation image of the tapered tip of the tapered fiber in the reaction region by metallographic microscope 7 after the fiber 3 is successfully inserted into the microchannel. After the laser 1 is turned on and the injection pump 2 injects the solution to start the photocatalytic hydrogen production reaction, the portion of the tapered tip loaded with photocatalyst begins to react and generate bubbles, such as... Figure 3As shown in (b), the metallurgical microscope 7 can observe and record the generation of bubbles during the reaction process. Therefore, the metallurgical microscope 7 can assist in inserting an optical fiber into the microchannel reactor 4 and observe the bubble generation process in situ. The higher the precision level of the metallurgical microscope, the clearer the observation of the reaction area will be.

Claims

1. A method for preparing a microchannel reactor for photocatalytic water splitting to produce hydrogen using an optical fiber cone tip, characterized in that: The photocatalytic water splitting to hydrogen microchannel reactor includes a main reaction channel (41), which is connected to a solution injection channel (42) and a solution outflow channel (43). The main reaction channel (41) is also connected to a laser (1) via an optical fiber (3). The end of the optical fiber (3) is subjected to a thermally stretched tapered treatment. The fiber core of the optical fiber (3) guides the laser emitted by the laser (1) through the tapered tip of the optical fiber. The tapered tip of the optical fiber (3) is loaded with a photocatalyst. The optical fiber (3) is connected to the laser (1) by optical fiber coupling, and the part of the optical fiber (3) entering the microchannel reactor (4) is sealed. The microchannel reactor (4) is made of a curable polymer material, including PDMS polydimethylsiloxane, epoxy resin or polyurethane; The inner diameter of the main reaction channel (41) of the microchannel reactor (4) is 250 μm – 400 μm, the inner diameter of the solution injection channel (42) of the microchannel reactor (4) is 0.4 mm – 1 mm, and the inner diameter of the solution outflow channel (43) of the microchannel reactor (4) is 0.4 mm – 1 mm. The preparation method of the photocatalytic water splitting microchannel reactor for hydrogen production includes the following specific steps: Step 1. Material preparation: Mix the prepolymer of the curing polymer and the curing agent at a mass ratio of 8:1 to 10:1 until homogeneous, vacuum degas for 20-30 minutes to eliminate air bubbles, and let stand at room temperature for 1-2 hours. Step 2. Substrate preparation: Use a spin coater to spin coat a layer of curable polymer onto a glass slide at a speed of 500-900 r / min to serve as a substrate. Heat and cure at 60-80℃ for 20-30 min. The thickness of the substrate is 1-10 mm. Step 3. Fabrication of tapered optical fiber: Take a 50-80cm length of optical fiber, clamp the fiber from both ends, peel off the coating layer in the middle 3-5cm of the fiber, burn the area where the coating layer was peeled off until it melts, fix one end still, and quickly pull the other end. The fiber will break at the burned point. The burned part of the fiber at the pulled end will be drawn into a tapered structure. Load the tapered part with a photocatalyst by physical impregnation. Step 4. Preparation of each channel: On the substrate prepared in step 2, according to the structure of the microchannel reactor (4), place the mold of the main reaction channel (41), the mold of the solution injection channel (42), the mold of the solution outflow channel (43), and the tapered optical fiber (3), pour on the curable polymer, heat and cure for 20-30 min, pull out the mold, and then heat and cure at 60-80℃ for 20-30 min to form the channel; Step 5. Channel connection and sealing: Use a punch to make small holes so that the main reaction channel (41) is connected to the solution injection channel (42) and the solution outflow channel (43) respectively. Then cut two pieces of cured polymer film with a thickness of 1-10mm, apply a layer of uncured polymer to one side and cover the outside of the small hole, heat and cure to seal the outside of the small hole.

2. The method for preparing a photocatalytic water splitting microchannel reactor for hydrogen production using an optical fiber cone tip focusing light source according to claim 1, characterized in that: The physical impregnation described in step 3 uses a photocatalyst. After ultrasonic homogenization for 20-40 minutes, the tapered fiber tip is immersed in the photocatalyst for 30-60 seconds and then air-dried for 30-60 seconds. This process is repeated 3-5 times. The photocatalyst is a metal sulfide semiconductor photocatalyst or a metal oxide semiconductor photocatalyst; the metal sulfide semiconductor photocatalyst includes cadmium sulfide and zinc sulfide; the metal oxide semiconductor photocatalyst includes zinc oxide and titanium dioxide.

3. The method for preparing a photocatalytic water splitting microchannel reactor for hydrogen production using an optical fiber cone tip focusing light source according to claim 1, characterized in that: The curable polymer is PDMS, epoxy resin or polyurethane; the curing agent is methyltriethoxysilane or methyltripropoxysilane.

4. A microchannel photocatalytic water splitting hydrogen production in-situ observation system based on the photocatalytic water splitting hydrogen production microchannel reactor of claim 1, characterized in that: The microchannel reactor (4) includes a main reaction channel (41) which is connected to a solution injection pump (2) via a solution injection channel (42), and to the liquid inflow channel of a gas-liquid collection sample bottle (5) via a solution outflow channel (43). It is also connected to a laser (1) via an optical fiber (3). The end of the optical fiber (3) is subjected to a thermally stretched tapered treatment, and the fiber core of the optical fiber guides the laser through the tapered tip of the optical fiber. The tapered tip of the optical fiber is loaded with a photocatalyst. The gas-liquid collection sample bottle (5) is connected to a gas chromatograph (6) via a gas delivery pipe. The microchannel reactor (4) is movably placed on the stage of a metallurgical microscope (7).

5. The in-situ observation system for microchannel photocatalytic water splitting to produce hydrogen based on a microchannel reactor with fiber optic cone tip focusing, as described in claim 4, is characterized in that: The optical fiber (3) is connected to the laser (1) by optical fiber coupling, and the optical fiber (3) is partially sealed when it enters the microchannel reactor (4); the laser (1) is a supercontinuum laser, and the wavelength of the light emitted by the laser (1) is in the ultraviolet and visible light bands.

6. The in-situ observation system for microchannel photocatalytic water splitting to produce hydrogen based on a microchannel reactor with fiber optic cone tip focusing, as described in claim 4, is characterized in that: The solution is a sacrificial reagent used in the photocatalytic reaction or pure water; the sacrificial reagent includes methanol, lactic acid, triethanolamine, sodium sulfite or sodium sulfide.

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