Preparation method of porous fluorescent film sensor and application thereof in NO2 gas concentration detection field
By fabricating a porous fluorescent thin film sensor and constructing a three-dimensional interconnected pore structure using the sacrificial template method, the problem of insufficient detection sensitivity of traditional fluorescent thin film sensors was solved, and high-sensitivity and rapid detection of NO2 gas was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2026-04-14
- Publication Date
- 2026-07-28
AI Technical Summary
Traditional organic polymer-based fluorescent thin film sensors have dense film formation, resulting in low specific surface area. This limits the effective contact probability and interaction efficiency between NO2 gas molecules and probe molecules, leading to insufficient detection sensitivity and making it difficult to meet the needs for trace, rapid, and accurate detection of NO2 in real-world complex environments.
A porous fluorescent thin-film sensor was prepared using the sacrificial template method. By using silica nanospheres as sacrificial templates, they were combined with organic polymers and fluorescent probe molecules to construct a composite fluorescent thin-film precursor. The silica nanospheres were then removed by a specific etching process to form a three-dimensional interconnected pore structure, which significantly increased the specific surface area and porosity.
It significantly improved the amplitude of fluorescence signal changes in the sensor, increased the number of active sites on the sensing interface that can interact with the target gas, promoted the rapid diffusion and penetration of NO2 gas molecules into the sensor, and achieved highly sensitive and rapid detection of NO2 gas.
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Figure CN122468675A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing a porous fluorescent thin film sensor and its application in the field of NO2 gas concentration detection. Background Technology
[0002] Fluorescent thin-film sensors, with their excellent stability, portability, and ability to achieve rapid, naked-eye visual identification under specific conditions, have shown broad application prospects in the field of gas sensing. However, traditional organic polymer-based fluorescent thin-film sensors generally suffer from inherent defects such as dense film structures and low specific surface areas, directly resulting in a limited number of active sites on the sensing interface that can interact with the target gas. Especially in the field of nitrogen dioxide (NO2) concentration detection, this dense film structure severely hinders the diffusion and penetration of NO2 gas molecules into the sensing layer, significantly reducing the effective contact probability and interaction efficiency between probe molecules and gas molecules. This leads to weak changes in fluorescence signal after gas-sensitive response, low signal discrimination, and ultimately insufficient detection sensitivity and high detection limits, making it difficult to meet the application requirements for trace, rapid, and accurate detection of NO2 in complex real-world environments. Summary of the Invention
[0003] This invention aims to address the problem that existing organic polymer fluorescent thin film sensors have dense film formation, low detection sensitivity, and are difficult to implement in practical applications. It provides a method for preparing a porous fluorescent thin film sensor and its application in the field of NO2 gas concentration detection.
[0004] A method for preparing a porous fluorescent thin-film sensor and its application in the field of NO2 gas concentration detection is disclosed, which is carried out according to the following steps: 1. Stir deionized water, anhydrous ethanol and ammonia until they are evenly mixed. Add tetraethyl orthosilicate (TEOS) dropwise to the deionized water-anhydrous ethanol-ammonia system. After the hydrolysis reaction is complete, centrifuge, wash and dry in sequence to obtain silica nanospheres.
[0005] The ammonia solution has a mass fraction of 28%; the volume ratio of deionized water: anhydrous ethanol: ammonia solution is 1:25:1; the reaction temperature is 70 ℃; the hydrolysis time is 1.5 h; the centrifugation conditions are centrifugation at 8000 r / min for 8 min; the washing conditions are washing 3 times each with anhydrous ethanol and deionized water; and the drying conditions are vacuum drying at 60 ℃ for 12 h.
[0006] 2. The silica nanospheres, polymers and fluorescent probe molecules prepared above are ultrasonically dispersed in a solvent to prepare a fluorescent precursor solution. The fluorescent precursor solution is uniformly coated onto a substrate and then cured to form a film, thus obtaining a solid fluorescent film.
[0007] The solvent is dichloromethane; the substrate is a clean, dry quartz plate or glass plate; the coating amount of the fluorescent precursor solution is 250 μL / cm². 2 The curing conditions are as follows: curing at room temperature for 18-24 hours.
[0008] 3. Peel the solid fluorescent film prepared above off the substrate, immerse it in an acid solution, and after ultrasonically dissolve the silica nanospheres in the solid fluorescent film completely, dry it to obtain a porous fluorescent film sensor.
[0009] The acid solution is a 5% hydrofluoric acid aqueous solution; the ultrasonic conditions are 100 W power for 120 min; and the drying conditions are vacuum drying at 60℃ for 12 h.
[0010] IV. The initial fluorescence value of the porous fluorescent thin film sensor prepared above was measured. I The porous fluorescent thin-film sensor was purged with NO2 standard gas of gradient concentration, and the final fluorescence value was measured after the purging was completed. I 0 The fluorescence signal change value α is calculated using the following formula, and a mathematical relationship is established between it and the corresponding NO2 standard gas concentration, thereby achieving high-sensitivity fluorescence sensing of NO2 concentration.
[0011] α = ( I 0 - I ) / I 0 The concentration of the gradient concentration NO2 standard gas is 1~100 ppm.
[0012] The beneficial effects of this invention are: This invention employs a sacrificial template method to prepare porous fluorescent thin-film sensors. The core fabrication concept involves using silica nanospheres as a sacrificial template, uniformly combining them with organic polymers and fluorescent probe molecules to construct a composite fluorescent thin-film precursor. Subsequently, a specific etching process completely removes the silica nanospheres from the film, utilizing the three-dimensional interconnected pore structure left after template etching to significantly increase the specific surface area and porosity of the fluorescent thin-film sensor. This porous structure design effectively addresses the inherent defects of traditional dense thin films: on the one hand, it significantly increases the number of active sites on the sensing interface that can interact with the target gas, providing sufficient reaction sites for the interaction between NO2 gas molecules and probe molecules; on the other hand, the three-dimensional interconnected pore structure breaks down gas diffusion barriers, significantly promoting the rapid diffusion and penetration of NO2 gas molecules into the sensor film, greatly increasing the effective contact probability and interaction efficiency between probe molecules and NO2 gas molecules, thereby significantly enhancing the fluorescence signal change amplitude during the gas-sensitive response process. This effectively solves the key problem of insufficient detection sensitivity in traditional sensors, achieving highly sensitive and rapid detection of NO2 gas. Attached Figure Description
[0013] Figure 1 This is a microscopic morphology image of the porous fluorescent thin film sensor prepared in step three of Example 1; Figure 2 A digital photograph of the porous fluorescent thin-film sensor prepared in Example 1; Figure 3 Fluorescence comparison images of the porous fluorescent thin film sensor prepared in Example 1 and the ordinary fluorescent thin film sensor prepared in the comparative experiment; Figure 4 The fluorescence intensity spectrum of the porous fluorescent thin film sensor prepared in Example 1 before and after being exposed to 1000ppm NO2 for 5 minutes; Figure 5 The correlation spectrum between the fluorescence signal change value of the porous fluorescent thin film sensor prepared in Example 1 and the NO2 concentration is shown. Detailed Implementation
[0014] Specific Implementation Method 1: A method for preparing a porous fluorescent thin film sensor and its application in the field of NO2 gas concentration detection, which is carried out according to the following steps: 1. Stir deionized water, anhydrous ethanol and ammonia until they are evenly mixed. Add tetraethyl orthosilicate (TEOS) dropwise to the deionized water-anhydrous ethanol-ammonia system. After the hydrolysis reaction is complete, centrifuge, wash and dry in sequence to obtain silica nanospheres.
[0015] The ammonia solution has a mass fraction of 28%; the volume ratio of deionized water: anhydrous ethanol: ammonia solution is 1:25:1; the reaction temperature is 70 ℃; the hydrolysis time is 1.5 h; the centrifugation conditions are centrifugation at 8000 r / min for 8 min; the washing conditions are washing 3 times each with anhydrous ethanol and deionized water; and the drying conditions are vacuum drying at 60 ℃ for 12 h.
[0016] 2. The silica nanospheres, polymers and fluorescent probe molecules prepared above are ultrasonically dispersed in a solvent to prepare a fluorescent precursor solution. The fluorescent precursor solution is uniformly coated onto a substrate and then cured to form a film, thus obtaining a solid fluorescent film.
[0017] The solvent is dichloromethane; the substrate is a clean, dry quartz plate or glass plate; the coating amount of the fluorescent precursor solution is 250 μL / cm². 2 The curing conditions are as follows: curing at room temperature for 18-24 hours.
[0018] 3. Peel the solid fluorescent film prepared above off the substrate, immerse it in an acid solution, and after ultrasonically dissolve the silica nanospheres in the solid fluorescent film completely, dry it to obtain a porous fluorescent film sensor.
[0019] The acid solution is a 5% hydrofluoric acid aqueous solution; the ultrasonic conditions are 100 W power for 120 min; and the drying conditions are vacuum drying at 60℃ for 12 h.
[0020] IV. The initial fluorescence value of the porous fluorescent thin film sensor prepared above was measured. I The porous fluorescent thin-film sensor was purged with NO2 standard gas, and the final fluorescence value was measured after the purging was completed. I 0 The fluorescence signal change value α is calculated using the following formula, and a mathematical relationship is established between it and the corresponding NO2 standard gas concentration, thereby achieving high-sensitivity fluorescence sensing of NO2 concentration.
[0021] α = ( I 0 - I ) / I 0 The concentration of the gradient concentration NO2 standard gas is 1~100 ppm.
[0022] The beneficial effects of this embodiment are: This embodiment employs a sacrificial template method to prepare a porous fluorescent thin-film sensor. The core fabrication concept is as follows: using silica nanospheres as a sacrificial template, they are uniformly composited with organic polymers and fluorescent probe molecules to construct a composite fluorescent thin-film precursor dominated by these three components. Subsequently, a specific etching process is used to completely etch away the silica nanospheres in the film. The three-dimensional interconnected pore structure left after template etching significantly increases the specific surface area and porosity of the fluorescent thin-film sensor. This porous structure design effectively addresses the inherent defects of traditional dense thin films: on the one hand, it significantly increases the number of active sites on the sensing interface that can interact with the target gas, providing sufficient reaction sites for the interaction between NO2 gas molecules and probe molecules; on the other hand, the three-dimensional interconnected pore structure can break down gas diffusion barriers, significantly promoting the rapid diffusion and penetration of NO2 gas molecules into the sensor film, greatly improving the effective contact probability and interaction efficiency between probe molecules and NO2 gas molecules. This significantly enhances the amplitude of fluorescence signal changes during the gas-sensitive response process, effectively solving the key problem of insufficient detection sensitivity in traditional sensors and achieving highly sensitive and rapid detection of NO2 gas.
[0023] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the volume ratio of tetraethyl orthosilicate to deionized water in step one is 0.1~1:1; and the dropping rate of the tetraethyl orthosilicate is 0.1~1 mL / min. Everything else is the same as in Specific Implementation Method One.
[0024] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the concentration of the silica nanospheres mentioned in step two is 0.05~0.3 g / mL. Everything else is the same as in Specific Implementation Method One or Two.
[0025] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that: the polymer mentioned in step two is polymethyl methacrylate, a mixture of polymethyl methacrylate and polyvinyl acetate in a mass ratio of 0.5 to 2:1, or a mixture of polymethyl methacrylate, polyvinyl acetate, and polyvinyl alcohol in a mass ratio of 2:1:1; the mass fraction of the polymer is 2 to 10%. Everything else is the same as in Specific Implementation Methods One to Three.
[0026] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: the fluorescent probe molecule mentioned in step two is perylene, rhodamine 6G, or rhodamine B; the concentration of the probe molecule is 10. -7 ~10 -2 mol / L. Other parameters are the same as in embodiments one through four.
[0027] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the area of the porous fluorescent thin film sensor described in step three is 1~10 cm². 2 Everything else is the same as in specific implementation methods one through five.
[0028] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that: the fluorescence detection device mentioned in step four is a fiber optic spectrometer; the purge time is 1~30 min; and the fluorescence detection wavelength is 350~595 nm. Everything else is the same as Specific Implementation Methods One to Six.
[0029] The beneficial effects of the present invention are verified using the following embodiments: Example
[0030] A method for preparing a porous fluorescent thin-film sensor and its application in the field of NO2 gas concentration detection is disclosed, which is carried out according to the following steps: 1. Stir 6 mL of deionized water, 160 mL of anhydrous ethanol and 8 mL of ammonia water until they are evenly mixed. Add 2 mL of tetraethyl orthosilicate (TEOS) dropwise to the deionized water-anhydrous ethanol-ammonia water system at a rate of 0.5 mL / min. After the hydrolysis reaction is completed, centrifuge, wash and dry in sequence to obtain silica nanospheres.
[0031] The ammonia solution has a mass fraction of 28%; the volume ratio of deionized water: anhydrous ethanol: ammonia solution is 1:25:1; the reaction temperature is 70 ℃; the hydrolysis time is 1.5 h; the centrifugation conditions are centrifugation at 8000 r / min for 8 min; the washing conditions are washing 3 times each with anhydrous ethanol and deionized water; and the drying conditions are vacuum drying at 60 ℃ for 12 h.
[0032] 2. The 0.3 g silica nanospheres, 0.66 g polymethyl methacrylate, 0.33 g polyvinyl acetate, 0.33 g polyvinyl alcohol and 0.5 mg perylene probe molecules prepared above were ultrasonically dispersed in 20 mL dichloromethane to prepare a fluorescent precursor solution. The fluorescent precursor solution was uniformly coated onto a substrate and then cured to form a film, thus obtaining a solid fluorescent film.
[0033] The solvent is dichloromethane; the substrate is a clean, dry quartz plate or glass plate; the coating amount of the fluorescent precursor solution is 250 μL / cm². 2 The curing conditions are as follows: curing at room temperature for 18-24 hours.
[0034] 3. Peel the solid fluorescent film prepared above off the substrate, immerse it in an acid solution, and after ultrasonic dissolution of the silica nanospheres in the solid fluorescent film, dry it to obtain a porous fluorescent film sensor with an area of 1cm×2cm.
[0035] The acid solution is a 5% hydrofluoric acid aqueous solution; the ultrasonic conditions are 100 W power for 120 min; and the drying conditions are vacuum drying at 60℃ for 12 h.
[0036] IV. The initial fluorescence value of the porous fluorescent thin film sensor prepared above was measured using a fiber optic spectrometer. I The porous fluorescent thin-film sensor was purged with standard NO2 gas at concentrations of 1 ppm, 10 ppm, 50 ppm, 80 ppm, and 100 ppm for 5 min, respectively. The final fluorescence value of the sensor was then measured. I 0 The fluorescence signal change value α was calculated using the following formula, and a mathematical relationship was established between it and the corresponding NO2 standard gas concentration. Through linear fitting, the relationship was obtained as y = 0.40x + 14.34, R0. 2 =0.96. The data records are shown in Table 1.
[0037] α = ( I 0 - I ) / I 0 The concentration of the gradient concentration NO2 standard gas is 1~100 ppm.
[0038] Table 1 Data Record Analysis Table 1 1 225 203 10 2 10 220 169 23 3 50 223 145 35 4 80 236 127 46 5 100 229 108 53 Comparative experiment: Under a power of 100W, polymethyl methacrylate and perylene probe molecules were ultrasonically dispersed in dichloromethane reagent to obtain a mother liquor. The mother liquor was then coated onto a quartz substrate (20mm×10mm×1mm) with a coating thickness of 1μm. After curing into a film, the film was peeled off to obtain a common fluorescent thin film sensor.
[0039] The concentration of polymethyl methacrylate in the mother liquor is 5 wt.%, and the concentration of probe molecules is 1 × 10⁻⁶. -4 mol / L.
[0040] Figure 1 The image shows the microstructure of the porous fluorescent thin film sensor prepared in step three of Example 1. As can be seen from the image, it has a pore structure with basically uniform size. Figure 2This is a digital photograph of the porous fluorescent thin film sensor prepared in Example 1. As can be seen from the figure, the film is intact. Figure 3 The images show a fluorescence comparison between the porous fluorescent thin film sensor prepared in Example 1 and the ordinary fluorescent thin film sensor prepared in the comparative experiment. As can be seen from the images, the porous fluorescent thin film sensor exhibits a stronger fluorescence intensity. Figure 4 The graph shows the fluorescence intensity of the porous fluorescent thin film sensor prepared in Example 1 before and after being exposed to 1000ppm NO2 for 5 minutes. As can be seen from the graph, its fluorescence is significantly quenched after contact with NO2. Figure 5 The graph shows the correlation between the fluorescence signal change value of the porous fluorescent thin film sensor prepared in Example 1 and the NO2 concentration. As can be seen from the graph, the fluorescence signal change value α of the porous fluorescent thin film sensor exhibits a good linear relationship with the NO2 concentration, satisfying the equation y = 0.40x + 14.34, R0. 2 =0.96.
Claims
1. A method for preparing a porous fluorescent thin-film sensor and its application in the field of NO2 gas concentration detection, characterized in that... It is done in the following steps:
1. Stir deionized water, anhydrous ethanol and ammonia until they are evenly mixed. Add tetraethyl orthosilicate (TEOS) dropwise to the deionized water-anhydrous ethanol-ammonia system. After the hydrolysis reaction is complete, centrifuge, wash and dry in sequence to obtain silica nanospheres. The ammonia solution has a mass fraction of 28%; the volume ratio of deionized water: anhydrous ethanol: ammonia solution is 1:25:1; the reaction temperature is 70 ℃; the hydrolysis time is 1.5 h; the centrifugation conditions are centrifugation at 8000 r / min for 8 min; the washing conditions are washing 3 times each with anhydrous ethanol and deionized water; and the drying conditions are vacuum drying at 60 ℃ for 12 h.
2. The silica nanospheres, polymers and fluorescent probe molecules prepared above are ultrasonically dispersed in a solvent to prepare a fluorescent precursor solution. The fluorescent precursor solution is uniformly coated onto a substrate and then cured to form a film, thus obtaining a solid fluorescent film. The solvent is dichloromethane; the substrate is a clean, dry quartz plate or glass plate; the coating amount of the fluorescent precursor solution is 250 μL / cm². 2 The curing conditions are as follows: curing at room temperature for 18-24 hours.
3. Peel the solid fluorescent film prepared above off the substrate, immerse it in an acid solution, and after ultrasonically dissolve the silica nanospheres in the solid fluorescent film completely, dry it to obtain a porous fluorescent film sensor. The acid solution is a 5% hydrofluoric acid aqueous solution; the ultrasonic conditions are 100 W power for 120 min; and the drying conditions are vacuum drying at 60℃ for 12 h. IV. The initial fluorescence value of the porous fluorescent thin film sensor prepared above was measured. I The porous fluorescent thin-film sensor was purged with NO2 standard gas of gradient concentration, and the final fluorescence value was measured after the purging was completed. I 0 The fluorescence signal change value α is calculated using the following formula, and a mathematical relationship is established between it and the corresponding NO2 standard gas concentration, thereby achieving high-sensitivity fluorescence sensing of NO2 concentration. α=（ I 0 - I ） / I 0 The concentration of the gradient concentration NO2 standard gas is 1~100 ppm.
2. The method for preparing a porous fluorescent thin-film sensor according to claim 1 and its application in the field of NO2 gas concentration detection, characterized in that... The volume ratio of tetraethyl orthosilicate to deionized water in step one is 0.1~1:1; the dropping rate of tetraethyl orthosilicate is 0.1~1 mL / min.
3. The method for preparing a porous fluorescent thin-film sensor according to claim 1 and its application in the field of NO2 gas concentration detection, characterized in that... The concentration of the silica nanospheres mentioned in step two is 0.05~0.3 g / mL.
4. The method for preparing a porous fluorescent thin-film sensor according to claim 1 and its application in the field of NO2 gas concentration detection, characterized in that... The polymer mentioned in step two is polymethyl methacrylate, a mixture of polymethyl methacrylate and polyvinyl acetate in a mass ratio of 0.5 to 2:1, or a mixture of polymethyl methacrylate, polyvinyl acetate and polyvinyl alcohol in a mass ratio of 2:1:1; the polymer has a mass fraction of 2 to 10%.
5. The method for preparing a porous fluorescent thin-film sensor according to claim 1 and its application in the field of NO2 gas concentration detection, characterized in that... The fluorescent probe molecule mentioned in step two is perylene, rhodamine 6G, or rhodamine B; the concentration of the probe molecule is 10. -7 ~10 -2 mol / L.
6. The method for preparing a porous fluorescent thin-film sensor according to claim 1 and its application in the field of NO2 gas concentration detection, characterized in that... The porous fluorescent thin-film sensor described in step three has an area of 1~10 cm². 2 .
7. The method for preparing a porous fluorescent thin-film sensor according to claim 1 and its application in the field of NO2 gas concentration detection, characterized in that... The fluorescence detection device mentioned in step four is a fiber optic spectrometer; the purging time is 1~30 min; and the fluorescence detection wavelength is 350~595 nm.