Precious metal-WO3 hydrogen-sensitive color-changing material as well as preparation method and application thereof

Abstract

The invention discloses a precious metal-WO3 hydrogen-sensitive color-changing material as well as a preparation method and application thereof. The preparation method comprises the following steps: ultrasonically dispersing WO3 nanoparticles in methanol, dropwise adding a methanol solution containing a noble metal-based material, or dropwise adding a methanol solution containing the noble metal-based material and polyvinylpyrrolidone, and uniformly stirring and dispersing to obtain a turbid liquid; and carrying out hydrothermal reaction or photochemical deposition reaction on the turbid liquid, centrifuging the reaction liquid, and collecting the obtained precipitate, namely the precious metal-WO3 hydrogen-sensitive color-changing material. The method is simple, efficient and low in cost, and the obtained precious hydrogen-sensitive color-changing material is used for hydrogen detection and has the advantages of being obvious in color-changing sensitivity, short in response time, capable of being repeatedly used and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic materials, and particularly relates to a precious metal-WO 3 Hydrogen-sensitive color-changing material and its preparation method and application. Background Art

[0002] 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.

[0003] 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.

[0004] Patent CN112592708A is to convert WO 3 With metal elements (Fe, Pt, Y) as active components, loaded on materials such as Al 2 O 3 、TiO 2 、SiO 2 , molecular sieves, kaolin, bentonite and diatomaceous earth and other carriers. This process involves 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, and is difficult to achieve large-scale production and application. Summary of the invention

[0005] In order to overcome the shortcomings and deficiencies of the prior art, the present invention aims to provide a noble metal-WO 3 Hydrogen sensitive color changing material.

[0006] Another object of the present invention is to provide the above-mentioned precious metal-WO 3 The invention discloses a method for preparing a hydrogen-sensitive color-changing material.

[0007] Another object of the present invention is to provide the above-mentioned precious metal-WO 3 Application of hydrogen-sensitive color-changing materials in hydrogen detection.

[0008] The present invention is achieved by: a precious metal-WO 3 A method for preparing a hydrogen-sensitive color-changing material, the method comprising the following steps: (1) Add 0.5~1.5g of WO 3 The nanoparticles are ultrasonically dispersed in 20-100 mL of methanol, and 5-20 mL of a methanol solution containing 5-15 mg of a noble metal-based material is added dropwise, or 5-20 mL of a methanol solution containing 5-15 mg of a noble metal-based material and 5-30 mg of polyvinyl pyrrolidone is added dropwise, and the mixture is stirred and dispersed 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; (2) The suspension is reacted at 100-180°C for 2-12 hours, the reaction solution is centrifuged, and the resulting precipitate is collected as the precious metal-WO 3 Hydrogen-sensitive color-changing materials; Alternatively, the suspension is reacted at room temperature under fluorescent light for 8 to 12 hours, wherein the power of the fluorescent light 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 the precious metal-WO 3 Hydrogen sensitive color changing material.

[0009] Preferably, in step (1), the mass ratio of palladium chloride to chloroplatinic acid in the mixed material is 1:1.

[0010] Preferably, in step (1), the dripping speed is 5-10 mL / min.

[0011] Preferably, in step (2), the centrifugation is performed at 10,000 rpm for 3 min.

[0012] Preferably, in step (2), the reaction solution is centrifuged to retain the upper layer solution, which is used to replace the noble metal-based material in step (1).

[0013] The present invention further discloses the precious metal-WO prepared by the above method 3 Hydrogen sensitive color changing material.

[0014] The present invention further discloses the above-mentioned precious metal-WO 3 Application of hydrogen-sensitive color-changing materials in hydrogen detection.

[0015] The present invention overcomes the shortcomings of the prior art and provides a precious metal-WO 3 Hydrogen-sensitive color-changing material and its preparation method and application.3 The nanoparticles are ultrasonically dispersed in methanol, a methanol solution containing a noble metal-based material is added dropwise, or a methanol solution containing a noble metal-based material and polyvinyl pyrrolidone is added dropwise, and the mixture is stirred and dispersed uniformly to obtain a suspension; the suspension is subjected to a hydrothermal reaction or a photochemical deposition reaction, the reaction solution is centrifuged, and the resulting precipitate is collected to obtain the noble metal-WO 3 Hydrogen sensitive color changing material.

[0016] In the present invention, from the perspective of physical form, the hydrogen-sensitive color-changing material is mainly composed of an internal color-changing layer (WO 3 ), the outermost catalytic layer (precious metal) forms a layered structure. From the functional state, the hydrogen-sensitive color-changing material is mainly composed of the inner base layer (WO 3 ), the middle layer (WO 3 ) and the outermost catalytic layer (precious metal) form a multi-level layered structure. 3 It can be used as the material of the base layer and the color-changing layer. In this structure, the WO 3 The specific surface area of ​​the hydrogen-sensitive color-changing material is increased. Its unique porous characteristics have a positive effect on the adsorption of hydrogen, which can increase the material's adsorption of hydrogen, thereby shortening the hydrogen-sensitive color-changing time and reducing the material's preparation cost. When the hydrogen-sensitive color-changing material comes into contact with hydrogen, the hydrogen is first activated by the precious metal in the catalytic layer and converted into active hydrogen atoms, which then react chemically with the color-changing layer. Specifically, the transition metal oxide (WO 3 ) is reduced to metal hydride by hydrogen, which causes the color change of the color-changing layer, and finally manifests as the color change of the hydrogen-sensitive color-changing material. In addition, when the hydrogen-sensitive color-changing material that has changed color is fully exposed to air, it can be restored to the initial color state, so the hydrogen-sensitive color-changing material can be recycled.

[0017] Compared with the shortcomings and deficiencies of the prior art, the present invention has the following beneficial effects: (1) The precious 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

[0018] Figure 1It is the color change and reduction process of the hydrogen-sensitive color-changing material 5 in the embodiment of the effect of the present invention; wherein, Figure a is the initial color of the hydrogen-sensitive color-changing material 5, Figure b is the color after the hydrogen-sensitive color-changing material 5 reacts completely with hydrogen, and Figure c is the color after the hydrogen-sensitive color-changing material 5 is fully reduced with air; Figure 2 This is the color change and reduction process of the hydrogen-sensitive color-changing material 7 in the embodiment of the present invention; wherein, Figure a is the initial color of the hydrogen-sensitive color-changing material 7, Figure b is the color after the hydrogen-sensitive color-changing material 7 reacts completely with hydrogen, and Figure c is the color after the hydrogen-sensitive color-changing material 7 is fully reduced with air; Figure 3 This is the color change and reduction process of the hydrogen-sensitive color-changing material 8 in the embodiment of the effect of the present invention; wherein, Figure a is the initial color of the hydrogen-sensitive color-changing material 8, Figure b is the color of the hydrogen-sensitive color-changing material 8 after complete reaction with hydrogen, and Figure c is the color of the hydrogen-sensitive color-changing material 8 after sufficient reduction with air. DETAILED DESCRIPTION

[0019] 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

[0020] (1) Add 2 g of sodium tungstate to 30 mL of deionized water, stir thoroughly to dissolve, add 20 mL of dilute sulfuric acid solution (water to sulfuric acid ratio is 1:2), react at 300 rpm for 24 h, wash the reaction product with deionized water 4 times at 10,000 rpm, each time for 3 min, dry the precipitate collected by centrifugation to obtain WO 3 Nanoparticles; 0.5 g WO 3 The nanoparticles were dispersed in 100 mL of methanol by ultrasound at 28 kHz, and 20 mL of a methanol solution containing 5 mg of palladium chloride was added dropwise at a rate of 5 mL / min, and stirred to disperse evenly to obtain a suspension; (2) The suspension was transferred into a polytetrafluoroethylene-lined crystallization reactor and reacted at 180°C for 12 h. The reaction solution was centrifuged at 10,000 rpm for 3 min and the resulting precipitate was collected as precious metal-WO 3 Hydrogen-sensitive color-changing material 1 (Pd-WO 3 Hydrogen-sensitive color-changing material). Example 2

[0021] (1) Add 2 g of sodium tungstate to 30 mL of deionized water, stir thoroughly to dissolve, add 20 mL of dilute sulfuric acid solution (water to sulfuric acid ratio is 1:2), react at 300 rpm for 24 h, wash the reaction product with deionized water 4 times at 10,000 rpm, each time for 3 min, dry the precipitate collected by centrifugation to obtain WO 3 Nanoparticles; 1.5 g WO 3 The nanoparticles were dispersed in 20 mL of methanol by ultrasound at 40 kHz, and 5 mL of a methanol solution containing 15 mg of palladium chloride was added dropwise at a rate of 10 mL / min, and stirred to disperse evenly to obtain a suspension; (2) The suspension was transferred into a polytetrafluoroethylene-lined crystallization reactor, reacted at 100°C for 2 hours, and the reaction solution was centrifuged at 10,000 rpm for 3 minutes to collect the resulting precipitate as precious metal-WO 3 Hydrogen-sensitive color-changing material 2 (Pd-WO 3 Hydrogen-sensitive color-changing material). Example 3

[0022] (1) Add 1g sodium tungstate to 40mL deionized water, stir thoroughly to dissolve, add 5mL dilute sulfuric acid solution (water to sulfuric acid ratio is 1:2), react for 24h under stirring at 300rpm, wash the reaction product with deionized water for 6 times under 10000rpm centrifugal state, each washing for 3min, dry the precipitate collected by centrifugation to obtain WO 3 Nanoparticles; 1.0 g WO 3 The nanoparticles were ultrasonically dispersed in 50 mL of methanol at 30 kHz, and 10 mL of a methanol solution containing 10 mg of a mixed material was added dropwise at a rate of 6 mL / min. The mixed material consisted of palladium chloride and chloroplatinic acid in a mass ratio of 1:1, and the mixture was stirred and dispersed uniformly to obtain a suspension. (2) The suspension was transferred into a polytetrafluoroethylene-lined crystallization reactor and 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 as precious metal-WO 3 Hydrogen-sensitive color-changing material 3 (Pd / Pt-WO 3 Hydrogen-sensitive color-changing material). Example 4

[0023] (1) Add 3 g of sodium tungstate to 10 mL of deionized water, stir thoroughly to dissolve, add 10 mL of dilute sulfuric acid solution (water to sulfuric acid ratio is 1:2), react for 24 h at 300 rpm, wash the reaction product with deionized water for 5 times at 10,000 rpm, each time for 3 min, dry the precipitate collected by centrifugation to obtain WO 3 Nanoparticles; 0.8g WO 3 The nanoparticles were dispersed in 60 mL of methanol by ultrasound at 35 kHz, and 15 mL of a methanol solution containing 12 mg of palladium chloride and 30 mg of polyvinyl pyrrolidone was added dropwise at a rate of 7 mL / min, and the mixture was stirred and dispersed uniformly to obtain a suspension; (2) The suspension was transferred into a polytetrafluoroethylene-lined crystallization reactor and reacted at 150°C for 7 h. The reaction solution was centrifuged at 10,000 rpm for 3 min and the resulting precipitate was collected as precious metal-WO 3 Hydrogen-sensitive color-changing material 4 (Pd-WO 3 Hydrogen-sensitive color-changing material). Example 5

[0024] (1) Add 3 g of sodium tungstate to 10 mL of deionized water, stir thoroughly to dissolve, add 10 mL of dilute sulfuric acid solution (water to sulfuric acid ratio is 1:2), react for 24 h at 300 rpm, wash the reaction product with deionized water for 5 times at 10,000 rpm, each time for 3 min, dry the precipitate collected by centrifugation to obtain WO 3 Nanoparticles; 1.2 g WO 3 The nanoparticles were ultrasonically dispersed in 85 mL of methanol at 40 kHz, and 12 mL of a methanol solution containing 8 mg of a mixed material and 5 mg of polyvinyl pyrrolidone was added dropwise at a rate of 9 mL / min. The mixed material consisted of palladium chloride and chloroplatinic acid in a mass ratio of 1:1, and the mixture was stirred and dispersed uniformly to obtain a suspension. (2) The suspension was transferred into a polytetrafluoroethylene-lined crystallization reactor and reacted at 140°C for 10 h. The reaction solution was centrifuged at 10,000 rpm for 3 min and the resulting precipitate was collected as precious metal-WO 3 Hydrogen-sensitive color-changing material 5 (Pd / Pt-WO 3 Hydrogen-sensitive color-changing material). Example 6

[0025] This embodiment 6 is basically the same as embodiment 1, except that in step (2): (2) The suspension was reacted at room temperature under fluorescent light for 8 hours, wherein the power of the fluorescent light was 30 W and the light intensity was 1000 Lux. The reaction solution was centrifuged at 10000 rpm for 3 min, and the resulting precipitate was collected as precious metal-WO 3 Hydrogen-sensitive color-changing material 6 (Pd-WO 3 Hydrogen-sensitive color-changing material). Example 7

[0026] This embodiment 7 is basically the same as embodiment 5, except that in step (2): (2) The suspension was reacted at room temperature under fluorescent light for 12 hours, wherein the power of the fluorescent light was 65 W and the light intensity was 500 Lux. The reaction solution was centrifuged at 10000 rpm for 3 min, and the resulting precipitate was collected as precious metal-WO 3 Hydrogen-sensitive color-changing material 7 (Pd / Pt-WO 3 Hydrogen-sensitive color-changing material). Example 8

[0027] This embodiment 7 is basically the same as embodiment 1, except that after step (2), it further includes the following steps: (3) Collect the upper layer solution obtained by centrifugation in step (2); add 1.0 g WO 3 The nanoparticles were ultrasonically dispersed in 50 mL of methanol, and 10 mL of a methanol solution containing 10 mg of palladium chloride was added dropwise at a rate of 9 mL / min, and stirred to disperse evenly to obtain a suspension; (4) The suspension was transferred into a polytetrafluoroethylene-lined crystallization reactor and reacted at 120°C for 3 h. The reaction solution was centrifuged at 10,000 rpm for 3 min and the resulting precipitate was collected as precious metal-WO 3 Hydrogen-sensitive color-changing material 8 (Pd-WO 3 Hydrogen-sensitive color-changing material). Effect Example

[0028] 1. After the hydrogen-sensitive color-changing materials 1 to 8 prepared in the above Examples 1 to 8 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 8 did not change.

[0029] 2. Color change reaction The hydrogen-sensitive color-changing materials 1 to 8 prepared in the above Examples 1 to 8 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.

[0030] The results show that the noble metal hydrogen-sensitive color-changing materials 1 to 8 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.

[0031] The color change reaction process of the hydrogen-sensitive color-changing material 5 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 5 in the glass bottle is light yellow ( Figure 1a), pure hydrogen gas with a flow rate of 300 mL / min is introduced, and the hydrogen-sensitive color-changing material 5 changes color the moment it contacts the pure hydrogen gas. After 10 to 30 seconds, the hydrogen-sensitive color-changing material 5 and the hydrogen gas react completely, and the color of the hydrogen-sensitive color-changing material 5 reaches the darkest color, and finally presents a dark blue color ( Figure 1 b), and during the subsequent continuous introduction of hydrogen, the color of the hydrogen-sensitive color-changing material 5 remained essentially unchanged. After the introduction of hydrogen into the vial was stopped and the hydrogen-sensitive color-changing material 5 was allowed to fully contact the air for 10 minutes, the hydrogen-sensitive color-changing material 5 gradually returned to its initial color state ( Figure 1 c). The hydrogen-sensitive color-changing material 5 restored to its original color state can be reused for hydrogen detection. After 20 cycles of the experiment, the hydrogen-sensitive color-changing material 5 has no effect on the color change sensitivity of hydrogen.

[0032] The color change reaction process of the hydrogen-sensitive color-changing material 7 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 7 in the glass bottle is light yellow ( Figure 2 a), pure hydrogen gas with a flow rate of 400 mL / min was introduced, and the hydrogen-sensitive color-changing material 7 changed color the moment it came into contact with pure hydrogen gas. After 10 to 30 seconds, the hydrogen-sensitive color-changing material 7 and hydrogen gas reacted completely, and the color of the hydrogen-sensitive color-changing material 7 reached the darkest color, and finally appeared gray-blue ( Figure 2 b), and during the subsequent continuous introduction of hydrogen, the color of the hydrogen-sensitive color-changing material 7 remained essentially unchanged. After the introduction of hydrogen into the vial was stopped and the hydrogen-sensitive color-changing material 7 was allowed to fully contact the air for 10 minutes, the hydrogen-sensitive color-changing material 7 gradually returned to its initial color state ( Figure 2 c). The hydrogen-sensitive color-changing material 7 restored to its original color state can be reused for hydrogen detection. After 20 cycles of the experiment, the hydrogen-sensitive color-changing material 7 has no effect on the color change sensitivity of hydrogen.

[0033] The color change reaction process of the hydrogen-sensitive color-changing material 8 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 8 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 8 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 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 8 minutes, the hydrogen-sensitive color-changing material 8 gradually returned to its initial color state ( Figure 3c). It can be seen that in Example 8, the reaction solution of step (2) 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 the preparation of 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.

[0034] 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 noble metal-WO3 hydrogen-sensitive color-changing material, characterized in that: The method comprises the following steps: (1) ultrasonically dispersing 0.5-1.5 g of WO3 nanoparticles in 20-100 mL of methanol, dropwise adding 5-20 mL of a methanol solution containing 5-15 mg of a precious metal-based material, or dropwise adding 5-20 mL of a methanol solution containing 5-15 mg of a precious metal-based material and 5-30 mg of polyvinyl pyrrolidone, stirring and dispersing the mixture uniformly to obtain a suspension; wherein the precious metal-based material is palladium chloride or a mixed material consisting of palladium chloride and chloroplatinic acid; (2) reacting the suspension at 100-180° C. for 2-12 hours, centrifuging the reaction solution, and collecting the resulting precipitate as a noble metal-WO3 hydrogen-sensitive color-changing material; Alternatively, the suspension is reacted at room temperature under fluorescent lamp for 8 to 12 hours, wherein the power of the fluorescent lamp is 30 to 65 W and the illumination intensity is 500 to 1000 Lux, the reaction solution is centrifuged, and the resulting precipitate is collected as the noble metal-WO3 hydrogen-sensitive color-changing material.

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

1.

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

4. The preparation method according to claim 1, characterized in that: In step (2), the centrifugation is performed at 10,000 rpm for 3 minutes.

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

6. The noble metal-WO3 hydrogen-sensitive color-changing material prepared by the method according to any one of claims 1 to 5.

7. Application of the noble metal-WO3 hydrogen-sensitive color-changing material according to claim 6 in hydrogen detection.

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