Multistage layer structure hydrogen-sensitive color-changing material as well as preparation method and application thereof

Abstract

The invention discloses a hydrogen-sensitive color-changing material with a multi-stage layer structure and a preparation method and application of the hydrogen-sensitive color-changing material. The preparation method comprises the following steps: dispersing a substrate material into deionized water, adding sodium tungstate dihydrate, uniformly dispersing, adding dilute sulphuric acid, and aging and washing at room temperature to obtain nanoparticles; the method comprises the following steps: ultrasonically dispersing nano-particles in methanol, dropwise adding methanol containing a noble metal-based material, or dropwise adding methanol containing the noble metal-based material and polyvinylpyrrolidone, transferring the obtained suspension into a Teflon-lined autoclave, and carrying out hydrothermal reaction, or carrying out hydrothermal reaction, washing and drying to obtain the noble metal-based material. And carrying out photochemical deposition reaction on the turbid liquid under the irradiation condition of a fluorescent lamp, centrifuging the reaction product, and collecting the obtained precipitate, thereby obtaining the hydrogen-sensitive color-changing material with the multi-stage layer structure. The hydrogen-sensitive color-changing material is used for hydrogen detection, and has the characteristics of obvious color change, short response time, no color fading under normal storage, reusability and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of inorganic materials, and in particular relates to a multi-level layer structure hydrogen-sensitive color-changing material and a preparation method and application thereof. Background Art

[0002] Hydrogen is an efficient, clean, and renewable energy source. However, hydrogen is very easy to leak during production, use, storage, and transportation. It is colorless and odorless, and is not easy to detect. In addition, hydrogen has strong permeability and a low lower explosion limit. Therefore, hydrogen leak detection is crucial to ensure safety.

[0003] Hydrogen-sensitive color-changing materials are materials that change color when exposed to hydrogen. The color-changing principle is usually based on the chemical reaction or physical change that occurs when the material comes into contact with hydrogen molecules. These changes may involve changes in electronic structure, lattice changes, or other changes in intermolecular forces, which in turn lead to color changes. Hydrogen-sensitive color-changing materials have broad application prospects in hydrogen leak detection. The presence of hydrogen can be intuitively displayed through color changes. This material can be used to monitor hydrogen leaks in real time and improve safety. For example, in hydrogen refueling stations, hydrogen fuel cell vehicles, chemical plants, hydrogen production industries and other places, hydrogen-sensitive color-changing materials can be used for leak detection in key areas such as pipelines and valves.

[0004] In recent years, researchers have improved the sensitivity and stability of materials by optimizing the material preparation process, doping and modification, and other methods. For example, advanced preparation techniques such as sol-gel method and magnetron sputtering method can be used to prepare hydrogen-sensitive films with high specific surface area and porous structure, thereby improving the hydrogen adsorption capacity and response speed of the material. In addition, the hydrogen-sensitive performance of the material can be further improved by doping with active substances such as precious metals and transition metal oxides.

[0005] Patent CN112592708A uses WO3 and metal elements (Fe, Pt, Y) as active ingredients and loads them on a variety of carriers such as Al2O3, TiO2, SiO2, molecular sieves, kaolin, bentonite and diatomaceous earth. This process covers a series of cumbersome steps such as impregnation, drying, reaction, roasting, remixing, standing, solid-liquid separation, secondary drying and re-roasting. Therefore, the process involved in this patent is not only complicated, but also has many steps, is time-consuming, and inefficient, making it difficult to achieve large-scale production and application. Summary of the invention

[0006] In order to overcome the shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide a multi-layer structured hydrogen-sensitive color-changing material.

[0007] Another object of the present invention is to provide a preparation method and application of the above-mentioned multi-layer structure hydrogen-sensitive color-changing material.

[0008] Another object of the present invention is to provide an application of the above-mentioned multi-layer structure hydrogen-sensitive color-changing material in hydrogen detection.

[0009] The present invention is achieved by a method for preparing a multi-layer structure hydrogen-sensitive color-changing material, the method comprising the following steps: (1) Dispersing 500-2000 mg of a base material into 20-100 mL of deionized water, adding 500-4000 mg of sodium tungstate dihydrate, uniformly dispersing, adding 5-20 mL of dilute sulfuric acid, aging reaction at room temperature for 23-25 ​​hours, washing the reaction solution with deionized water under centrifugal conditions at 10000 rpm to obtain nanoparticles; wherein the base material is selected from any one of mesoporous silica, silica particles, thin layer chromatography silica gel and MoO3; (2) dispersing 0.25-1 g of the nanoparticles in 20-30 mL of methanol by ultrasonic dispersion at 28 khz-40 khz, adding dropwise 5-20 mL of methanol containing 5-15 mg of a noble metal-based material, or adding dropwise 5-20 mL of methanol containing 5-15 mg of a noble metal-based material and 5-30 mg of polyvinyl pyrrolidone, and mixing them uniformly to obtain a suspension; wherein the noble metal-based material is palladium chloride or a mixed material consisting of palladium chloride and chloroplatinic acid; (3) reacting the suspension at 100-180°C for 2-12 hours, centrifuging the reaction solution, and collecting the resulting precipitate as a multi-layered hydrogen-sensitive color-changing material; Alternatively, the suspension is irradiated with a fluorescent lamp at room temperature for 8 to 12 hours, wherein the power of the fluorescent lamp is 30 to 65 W and the light intensity is 500 to 1000 Lux, the reaction solution is centrifuged, and the resulting precipitate is collected as a multi-level layered hydrogen-sensitive color-changing material.

[0010] Preferably, in step (1), the volume ratio of water to sulfuric acid in the dilute sulfuric acid is 1:1-2.

[0011] Preferably, in step (2), the dropping rate is 5-10 mL / min.

[0012] Preferably, in step (2), the mass ratio of palladium chloride to chloroplatinic acid in the mixed material is 1:1.

[0013] Preferably, in step (3), the centrifugation is performed at 10,000 rpm for 3 min.

[0014] Preferably, in step (3), the reaction solution is centrifuged to retain the upper layer solution, which is used to replace the noble metal-based material in step (2).

[0015] The invention further discloses a multi-level layer structure hydrogen-sensitive color-changing material prepared by the method.

[0016] The present invention further discloses the application of the multi-level layer structure hydrogen-sensitive color-changing material in hydrogen detection.

[0017] The present invention overcomes the deficiencies of the prior art and provides a multi-level layered hydrogen-sensitive color-changing material and a preparation method and application thereof. The present invention disperses the base material in deionized water, adds sodium tungstate dihydrate, disperses it evenly, adds dilute sulfuric acid, ages it at room temperature for 24 hours, and washes it to obtain nanoparticles (SiO2 / WO3 nanoparticles, or MoO3 / WO3 nanoparticles); ultrasonically disperses the nanoparticles in methanol, drops methanol containing a noble metal-based material, or drops methanol containing a noble metal-based material and polyvinyl pyrrolidone, transfers the obtained suspension into a Teflon-lined autoclave for hydrothermal reaction, or performs a photochemical deposition reaction on the suspension under fluorescent lamp irradiation, centrifuges the reaction product, and collects the obtained precipitate as a multi-level layered hydrogen-sensitive color-changing material.

[0018] In the present invention, the hydrogen-sensitive color-changing material is mainly composed of a multi-level layered structure formed by an inner substrate layer (SiO2 or MoO3), an intermediate color-changing layer (WO3), and an outermost catalyst layer (precious metal). In this structure, the SiO2 or MoO3 of the substrate layer increases the specific surface area of ​​the hydrogen-sensitive color-changing material, and its unique porous characteristics have a positive effect on the adsorption of hydrogen, which can increase the amount of hydrogen adsorbed by the material, thereby shortening the time of hydrogen-sensitive color change, and also reducing the preparation cost of the material; when the hydrogen-sensitive color-changing material contacts with hydrogen, the hydrogen is first activated by the precious metal of the catalyst layer and converted into active hydrogen atoms, which then react chemically with the color-changing layer. Specifically, the transition metal oxide (WO3) in the color-changing layer is reduced to metal hydride by hydrogen, thereby causing a change in the color of the color-changing layer, and finally manifesting as a change in the color of the hydrogen-sensitive color-changing material. In addition, when the hydrogen-sensitive color-changing material that has changed color is fully in contact with the air, it can be restored to its initial color state, so the hydrogen-sensitive color-changing material can be recycled.

[0019] Compared with the shortcomings and deficiencies of the prior art, the present invention has the following beneficial effects: (1) The hydrogen-sensitive color-changing material of the present invention has the characteristics of not fading under normal storage and being environmentally friendly. In addition, the hydrogen-sensitive color-changing material changes color obviously after contacting hydrogen, has a short response time, and has excellent hydrogen color-changing sensitivity and indication effect; (2) The hydrogen-sensitive color-changing material of the present invention can return to its initial color state in the air after being out of contact with hydrogen, and the hydrogen-sensitive color-changing material can be reused; (3) The preparation method of the hydrogen-sensitive color-changing material of the present invention is simple and efficient, and the heavy metal raw materials can be reused in the subsequent preparation process of the catalytic layer, which greatly reduces the cost of the materials and is conducive to industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the color change and reduction process of the hydrogen-sensitive color-changing material 4 in the embodiment of the effect of the present invention; wherein, Figure a is the initial color of the hydrogen-sensitive color-changing material 4, Figure b is the color after the hydrogen-sensitive color-changing material 4 reacts completely with hydrogen, and Figure c is the color after the hydrogen-sensitive color-changing material 4 is fully reduced with air; Figure 2 This is the color change and reduction process of the hydrogen-sensitive color-changing material 8 in the embodiment of the present invention; wherein, Figure a is the initial color of the hydrogen-sensitive color-changing material 8, Figure b is the color after the hydrogen-sensitive color-changing material 8 completely reacts with hydrogen, and Figure c is the color after the hydrogen-sensitive color-changing material 8 is fully reduced with air; Figure 3 This is the color change and reduction process of the hydrogen-sensitive color-changing material 10 in the embodiment of the effect of the present invention; wherein, Figure a is the initial color of the hydrogen-sensitive color-changing material 10, Figure b is the color after the hydrogen-sensitive color-changing material 10 completely reacts with hydrogen, and Figure c is the color of the hydrogen-sensitive color-changing material 10 after being fully reduced to air. DETAILED DESCRIPTION

[0021] 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 accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Example 1

[0022] (1) 20 mL of hexadecyltrimethylammonium bromide and 1 mL of triethanolamine were mixed, 10 mL of ethyl silicate was added, and the mixture was reacted at 95°C for 1 hour. The reaction product was added into 100 mL of a saturated methanol solution of sodium chloride (the mass molar concentration of NaCl in methanol at room temperature is 0.238 mol / kg) and stirred to extract the hexadecyltrimethylammonium bromide. The mixture was washed with a washing liquid for 4 times at 8000 rpm for 10 minutes each time to obtain mesoporous silica; wherein the washing liquid was prepared by 1 part by volume of cyclohexane and 2 parts by volume of anhydrous ethanol; 500 mg of mesoporous silica was dispersed in 100 mL of deionized water, 4000 mg of sodium tungstate dihydrate was added, and the mixture was evenly dispersed. 20 mL of dilute sulfuric acid (the volume ratio of water to sulfuric acid was 1:1) was added, and the mixture was aged at room temperature for 25 hours. The reaction solution was washed with deionized water under centrifugal conditions at 10000 rpm to obtain SiO2 / WO3 nanoparticles. (2) 1 g SiO2 / WO3 nanoparticles were ultrasonically dispersed in 20 mL methanol at 28 kHz, and 5 mL of methanol containing 5 mg of palladium chloride was added dropwise at a rate of 10 mL / min. The mixture was mixed evenly to obtain a suspension. (3) The suspension was reacted at 180° C. for 2 h, the reaction solution was centrifuged at 10,000 rpm for 3 min, and the resulting precipitate was collected to obtain a multi-layered hydrogen-sensitive color-changing material 1 (Pd-SiO2 / WO3 hydrogen-sensitive color-changing material). Example 2

[0023] (1) 20 mL of hexadecyltrimethylammonium bromide and 1 mL of triethanolamine were mixed, 10 mL of ethyl silicate was added, and the mixture was reacted at 95°C for 1 hour. The reaction product was added into 100 mL of a saturated methanol solution of sodium chloride (the mass molar concentration of NaCl in methanol at room temperature is 0.238 mol / kg) and stirred to extract the hexadecyltrimethylammonium bromide. The mixture was washed with a washing liquid for 4 times at 8000 rpm for 10 minutes each time to obtain mesoporous silica; wherein the washing liquid was prepared by 1 part by volume of cyclohexane and 2 parts by volume of anhydrous ethanol; 2000 mg of mesoporous silica was dispersed in 20 mL of deionized water, 500 mg of sodium tungstate dihydrate was added, and the mixture was evenly dispersed. 5 mL of dilute sulfuric acid (the volume ratio of water to sulfuric acid was 1:2) was added, and the mixture was aged at room temperature for 23 hours. The reaction solution was washed with deionized water under centrifugal conditions at 10000 rpm to obtain SiO2 / WO3 nanoparticles. (2) 0.25 g SiO2 / WO3 nanoparticles were ultrasonically dispersed in 30 mL methanol at 40 kHz, and 20 mL of methanol containing 15 mg of a mixed material was added dropwise at a rate of 5 mL / min to mix evenly to obtain a suspension; wherein the mixed material was composed of palladium chloride and chloroplatinic acid in a mass ratio of 1:1; (3) The suspension was reacted at 100° C. for 12 h, the reaction solution was centrifuged at 10,000 rpm for 3 min, and the resulting precipitate was collected to obtain a multi-layered hydrogen-sensitive color-changing material 2 (Pd / Pt-SiO2 / WO3 hydrogen-sensitive color-changing material). Example 3

[0024] (1) 20 mL of hexadecyltrimethylammonium bromide and 1 mL of triethanolamine were mixed, 10 mL of ethyl silicate was added, and the mixture was reacted at 95°C for 1 hour. The reaction product was added into 100 mL of a saturated methanol solution of sodium chloride (the mass molar concentration of NaCl in methanol at room temperature is 0.238 mol / kg) and stirred to extract the hexadecyltrimethylammonium bromide. The mixture was washed with a washing liquid for 4 times at 8000 rpm for 10 minutes each time to obtain mesoporous silica; wherein the washing liquid was prepared by 1 part by volume of cyclohexane and 2 parts by volume of anhydrous ethanol; 1000 mg of mesoporous silica was dispersed in 50 mL of deionized water, 2000 mg of sodium tungstate dihydrate was added, and the mixture was evenly dispersed. 10 mL of dilute sulfuric acid (the volume ratio of water to sulfuric acid was 1:2) was added, and the mixture was aged at room temperature for 24 hours. The reaction solution was washed with deionized water under centrifugal conditions at 10000 rpm to obtain SiO2 / WO3 nanoparticles. (2) 0.5 g SiO2 / WO3 nanoparticles were dispersed in 25 mL methanol by ultrasonic dispersion at 30 kHz, and 15 mL methanol containing 10 mg palladium chloride and 20 mg polyvinyl pyrrolidone was added dropwise at a rate of 8 mL / min to obtain a suspension; (3) The suspension was reacted at 140° C. for 6 h, the reaction solution was centrifuged at 10,000 rpm for 3 min, and the resulting precipitate was collected to obtain a multi-layered hydrogen-sensitive color-changing material 3 (Pd-SiO2 / WO3 hydrogen-sensitive color-changing material). Example 4

[0025] (1) 20 mL of hexadecyltrimethylammonium bromide and 1 mL of triethanolamine were mixed, 10 mL of ethyl silicate was added, and the mixture was reacted at 95°C for 1 hour. The reaction product was added into 100 mL of a saturated methanol solution of sodium chloride (the mass molar concentration of NaCl in methanol at room temperature is 0.238 mol / kg) and stirred to extract the hexadecyltrimethylammonium bromide. The mixture was washed with a washing liquid for 4 times at 8000 rpm for 10 minutes each time to obtain mesoporous silica; wherein the washing liquid was prepared by 1 part by volume of cyclohexane and 2 parts by volume of anhydrous ethanol; 1500 mg of mesoporous silica was dispersed in 50 mL of deionized water, 1500 mg of sodium tungstate dihydrate was added, and the mixture was evenly dispersed. 10 mL of dilute sulfuric acid (the volume ratio of water to sulfuric acid was 1:1) was added, and the mixture was aged at room temperature for 24 hours. The reaction solution was washed with deionized water under centrifugal conditions at 10000 rpm to obtain SiO2 / WO3 nanoparticles. (2) 0.45 g SiO2 / WO3 nanoparticles were ultrasonically dispersed in 25 mL methanol at 35 kHz, and 18 mL methanol containing 10 mg mixed material and 15 mg polyvinyl pyrrolidone was added dropwise at a rate of 6 mL / min to mix evenly to obtain a suspension; wherein the mixed material was composed of palladium chloride and chloroplatinic acid in a mass ratio of 1:1; (3) The suspension was reacted at 140° C. for 7 h, the reaction solution was centrifuged at 10,000 rpm for 3 min, and the resulting precipitate was collected to obtain a multi-layered hydrogen-sensitive color-changing material 4 (Pd / Pt-SiO2 / WO3 hydrogen-sensitive color-changing material). Example 5

[0026] (1) 5 mL of ethyl silicate, 100 mL of ethanol, and 5 mL of ammonia solution (the volume ratio of concentrated ammonia to water is 2:1) were mixed in a beaker, and magnetic stirring was performed in a water bath at 25°C to promote the growth of silica particles. The obtained silica particles were washed four times with ethanol and centrifuged at 8000 rpm, each time for 10 min; the washed silica particles were vacuum dried; 1500 mg of silica particles were dispersed in 40 mL of deionized water, 2500 mg of sodium tungstate dihydrate was added, and the mixture was evenly dispersed. 10 mL of dilute sulfuric acid (the volume ratio of water to sulfuric acid was 1:2) was added, and the mixture was aged at room temperature for 24 hours. The reaction solution was washed with deionized water under centrifugal conditions at 10000 rpm to obtain SiO2 / WO3 nanoparticles. (2) 0.45 g SiO2 / WO3 nanoparticles were dispersed in 25 mL methanol by ultrasonic dispersing at 30 kHz, and 15 mL methanol containing 8 mg palladium chloride was added dropwise at a rate of 9 mL / min, and mixed evenly to obtain a suspension; (3) The suspension was reacted at 130° C. for 5 h, the reaction solution was centrifuged at 10,000 rpm for 3 min, and the resulting precipitate was collected to obtain a multi-layered hydrogen-sensitive color-changing material 5 (Pd-SiO2 / WO3 hydrogen-sensitive color-changing material). Example 6

[0027] This Example 6 is basically the same as the above Example 1, except that the mesoporous silica in step (1) is replaced by thin layer chromatography silica gel, and a multi-layer structure hydrogen-sensitive color-changing material 6 (Pd-SiO2 / WO3 hydrogen-sensitive color-changing material) is finally obtained. Example 7

[0028] (1) Disperse 1600 mg of MoO3 in 60 mL of deionized water, add 3500 mg of sodium tungstate dihydrate, disperse evenly, add 15 mL of dilute sulfuric acid (the volume ratio of water to sulfuric acid is 1:2), age and react at room temperature for 24 hours, and wash the reaction solution with deionized water under centrifugal conditions at 10000 rpm to obtain MoO3 / WO3 nanoparticles; (2) 0.35 g of MoO3 / WO3 nanoparticles were dispersed in 20 mL of methanol by ultrasonication at 28 kHz, and 10 mL of methanol containing 15 mg of palladium chloride was added dropwise at a rate of 7 mL / min, and mixed evenly to obtain a suspension; (3) The suspension was reacted at 130° C. for 10 h, the reaction solution was centrifuged, and the resulting precipitate was collected to obtain a multi-layered hydrogen-sensitive color-changing material 7 (Pd-MoO3 / WO3 hydrogen-sensitive color-changing material). Example 8

[0029] This Example 8 is basically the same as Example 1, except that in step (3), the obtained suspension is irradiated with a fluorescent lamp at room temperature for 8 hours, the power of the fluorescent lamp is 30 W, and the light intensity is 1000 Lux. The reaction liquid is centrifuged and the obtained precipitate is collected to obtain a multi-layer structure hydrogen-sensitive color-changing material 8 (Pd-SiO2 / WO3 hydrogen-sensitive color-changing material). Example 9

[0030] This Example 9 is basically the same as Example 2, except that in step (3), the obtained suspension is irradiated with a fluorescent lamp at room temperature for 12 hours, the power of the fluorescent lamp is 65 W, and the light intensity is 500 Lux. The reaction liquid is centrifuged and the obtained precipitate is collected to obtain a multi-layer structure hydrogen-sensitive color-changing material 9 (Pd / Pt-SiO2 / WO3 hydrogen-sensitive color-changing material). Example 10

[0031] This embodiment 10 is basically the same as embodiment 1, except that after step (3), it further includes the following steps: (4) Collect the upper layer solution obtained by centrifugation in step (3); disperse 1 g of SiO2 / WO3 nanoparticles in 20 mL of methanol by ultrasonic dispersion at 28 kHz, add 15 mL of the upper layer solution dropwise at a rate of 5 mL / min, mix well, and obtain a suspension; (5) The suspension was reacted at 130° C. for 6 h, the reaction solution was centrifuged at 10,000 rpm for 3 min, and the resulting precipitate was collected to obtain a multi-layered hydrogen-sensitive color-changing material 10 (Pd-SiO2 / WO3 hydrogen-sensitive color-changing material). Effect Example

[0032] 1. After the hydrogen-sensitive color-changing materials 1 to 10 prepared in the above Examples 1 to 10 were exposed to an indoor environment at normal temperature and pressure for 1 month, the observation results showed that the colors of the hydrogen-sensitive color-changing materials 1 to 10 did not change.

[0033] 2. Color change reaction The hydrogen-sensitive color-changing materials 1 to 10 prepared in the above Examples 1 to 10 were subjected to a color-changing reaction. Specifically, the hydrogen-sensitive color-changing material was placed in a 20 mL transparent glass vial, and then pure hydrogen gas was introduced at a flow rate of 300 to 600 mL / min, and the color change of the hydrogen-sensitive material was recorded.

[0034] The results show that hydrogen-sensitive color-changing materials 1 to 10 all change color instantly after contacting hydrogen, and the color changes to the darkest after 10 to 30 seconds. The color-changing effect is very significant and the response speed is fast.

[0035] The color change reaction process of the hydrogen-sensitive color-changing material 4 is as follows: Figure 1 As shown. Figure 1 It can be seen that before the hydrogen is introduced, the color of the hydrogen-sensitive color-changing material 4 in the glass bottle is light yellow ( Figure 1 a), pure hydrogen gas with a flow rate of 300 mL / min was introduced, and the hydrogen-sensitive color-changing material 4 changed color the moment it came into contact with pure hydrogen gas. After 10 to 30 seconds, the hydrogen-sensitive color-changing material 4 and hydrogen gas reacted completely, and the color of the hydrogen-sensitive color-changing material 4 reached the darkest color, and finally showed gray-green ( Figure 1 b), and during the subsequent continuous introduction of hydrogen, the color of the hydrogen-sensitive color-changing material 4 remained essentially unchanged. After the introduction of hydrogen into the vial was stopped and the hydrogen-sensitive color-changing material 4 was allowed to fully contact the air for 10 minutes, the hydrogen-sensitive color-changing material 4 gradually returned to its initial color state ( Figure 1 c). The hydrogen-sensitive color-changing material 4 restored to its original color state can be reused for hydrogen detection. After 20 cycles of the experiment, the hydrogen-sensitive color-changing material 4 has no effect on the color change sensitivity of hydrogen.

[0036] The color change reaction process of the hydrogen-sensitive color-changing material 8 is as follows: Figure 2 As shown. Figure 2 It can be seen that before the hydrogen is introduced, the color of the hydrogen-sensitive color-changing material 8 in the glass bottle is light yellow ( Figure 2 a), pure hydrogen gas with a flow rate of 300 mL / min is introduced, and the hydrogen-sensitive color-changing material 8 changes color the moment it contacts the pure hydrogen gas. After 10 to 30 seconds, the hydrogen-sensitive color-changing material 8 and the hydrogen gas react completely, and the color of the hydrogen-sensitive color-changing material 8 reaches the darkest color, and finally presents a gray-green color ( Figure 2 b), and during the subsequent continuous introduction of hydrogen, the color of the hydrogen-sensitive color-changing material 8 remained essentially unchanged. After the introduction of hydrogen into the vial was stopped and the hydrogen-sensitive color-changing material 8 was allowed to fully contact the air for 10 minutes, the hydrogen-sensitive color-changing material 8 gradually returned to its initial color state ( Figure 2 c). The hydrogen-sensitive color-changing material 8 restored to its original color state can be reused for hydrogen detection. After 20 cycles of the experiment, the hydrogen-sensitive color-changing material 8 has no effect on the color change sensitivity of hydrogen.

[0037] The color change reaction process of the hydrogen-sensitive color-changing material 10 is as follows: Figure 3 As shown. Figure 3 It can be seen that before the hydrogen is introduced, the color of the hydrogen-sensitive color-changing material 10 in the glass bottle is yellow-white ( Figure 3 a) When hydrogen was introduced at a flow rate of 600 mL / min, the hydrogen-sensitive color-changing material 10 changed color instantly, and the color reached the darkest dark green after 10-20 seconds ( Figure 3 b), and during the subsequent continuous introduction of hydrogen, the color of the hydrogen-sensitive color-changing material 10 basically does not change. After the introduction of hydrogen into the vial is stopped and the hydrogen-sensitive color-changing material 10 is fully exposed to air for 8 minutes, the hydrogen-sensitive color-changing material 10 gradually returns to its initial color state ( Figure 3 c). It can be seen that in Example 10, the reaction solution of step (3) of Example 1 is centrifuged and the upper solution is collected. The heavy metal raw material (Pd) in the upper solution can be reused for preparing the catalytic layer of the hydrogen-sensitive color-changing material, and the color-changing effect and color-changing response ability of the obtained hydrogen-sensitive color-changing material are basically unchanged, which can greatly reduce the material loss cost and is conducive to industrial application.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a multi-layer structure hydrogen-sensitive color-changing material, characterized in that: The method comprises the following steps: (1) Dispersing 500-2000 mg of a base material into 20-100 mL of deionized water, adding 500-4000 mg of sodium tungstate dihydrate, uniformly dispersing, adding 5-20 mL of dilute sulfuric acid, aging reaction at room temperature for 23-25 ​​hours, washing the reaction solution with deionized water under centrifugal conditions at 10000 rpm to obtain nanoparticles; wherein the base material is selected from any one of mesoporous silica, silica particles, thin layer chromatography silica gel and MoO3; (2) dispersing 0.25-1 g of the nanoparticles in 20-30 mL of methanol by ultrasonic dispersion at 28 khz-40 khz, adding dropwise 5-20 mL of methanol containing 5-15 mg of a noble metal-based material, or adding dropwise 5-20 mL of methanol containing 5-15 mg of a noble metal-based material and 5-30 mg of polyvinyl pyrrolidone, and mixing them uniformly to obtain a suspension; wherein the noble metal-based material is palladium chloride or a mixed material consisting of palladium chloride and chloroplatinic acid; (3) reacting the suspension at 100-180°C for 2-12 hours, centrifuging the reaction solution, and collecting the resulting precipitate as a multi-layered hydrogen-sensitive color-changing material; Alternatively, the suspension is irradiated with a fluorescent lamp at room temperature for 8 to 12 hours, wherein the power of the fluorescent lamp is 30 to 65 W and the light intensity is 500 to 1000 Lux, the reaction solution is centrifuged, and the resulting precipitate is collected as a multi-level layered hydrogen-sensitive color-changing material.

2. The preparation method according to claim 1, characterized in that In step (1), the volume ratio of water to sulfuric acid in the dilute sulfuric acid is 1:1-2.

3. The preparation method according to claim 1, characterized in that: In step (2), the dropping speed is 5-10 mL / min.

4. The preparation method according to claim 1, characterized in that: In step (2), the mass ratio of palladium chloride to chloroplatinic acid in the mixed material is 1:

1.

5. The preparation method according to claim 1, characterized in that: In step (3), the centrifugation is performed at 10,000 rpm for 3 minutes.

6. The preparation method according to claim 1, characterized in that: In step (3), the reaction solution is centrifuged to retain the upper layer solution, which is used to replace the precious metal-based material in step (2).

7. A multi-level layered hydrogen-sensitive color-changing material prepared by the method according to any one of claims 1 to 6.

8. Use of the multi-layer structure hydrogen-sensitive color-changing material according to claim 8 in hydrogen detection.

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