Preparation method of vanadium-containing modified tungsten oxide-titanium dioxide composite hydrogen-sensitive color-changing material

Abstract

The present application belongs to hydrogen sensitive material technical field, especially to a kind of preparation method of vanadium-containing modified tungsten oxide-titanium dioxide composite hydrogen sensitive color-changing material, comprising the following steps, S1: selecting ammonium metatungstate and ammonium metavanadate as raw material, adding deionized water, stirring and dissolving, adding titanium dioxide, ultrasonic dispersion and magnetic stirring for 30 minutes to form uniform suspension liquid;S2: the mixed solution obtained in S1 is dried to constant weight in oven, and the dry powder is placed in muffle furnace and calcined;S3: chloroplatinic acid is weighed and dissolved in deionized water, the dry powder obtained in S2 is added to the solution, stirred evenly, dried, and then calcined in muffle furnace to form Pt-loaded composite material;The color of the material prepared in S3 changes from light gray to dark blue after encountering hydrogen.The whole preparation and detection process is efficient, fast in response, simple in process flow, and without secondary pollution.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen-sensitive materials technology, and particularly relates to a method for preparing a vanadium-modified tungsten oxide-titanium dioxide composite hydrogen-sensitive color-changing material. Background Technology

[0002] Hydrogen is widely used in fuel cell vehicles, hydrogen storage systems, and distributed hydrogen pipelines. Its leakage poses a significant explosion risk, making real-time monitoring of low-concentration hydrogen a critical safety requirement. However, existing hydrogen sensors generally have limitations: semiconductor sensors typically require high temperatures of 200–400 °C to achieve sufficient sensitivity; palladium-based sensors have narrow detection ranges and are prone to saturation at low concentrations; optical hydrogen sensors often rely on precision instruments, making large-area, portable, or low-cost deployment difficult. These shortcomings prevent current technologies from achieving wide-range, rapid, and visualized hydrogen leak monitoring at room temperature, making them particularly unsuitable for applications such as onboard micro-leakage monitoring and flexible patch-based monitoring.

[0003] Tungsten oxide (WO3) is a typical hydrogen-sensitive color-changing material with excellent optical modulation capabilities and reversible color-changing properties, and is widely used in smart windows, gas sensors, and energy devices. However, traditional WO3 materials exhibit slow color-changing response speed and poor cycle stability under hydrogen gas. To improve its performance, researchers often introduce noble metals (such as Pt) or transition metal oxides (such as TiO2) to construct composite systems to enhance electron migration and hydrogen diffusion rates.

[0004] However, the WO3–TiO2 system still suffers from electron localization and interface barrier issues, affecting its color-changing response efficiency. Ammonium metavanadate (NH4VO3) can provide V during calcination. 5+ Ions, through heterovalent substitution of W 6+ Introducing oxygen vacancies and electronic defects helps improve hydrogen intercalation kinetics and optical modulation properties. Therefore, developing a vanadium-modified WO3–TiO2 composite system is of great significance. (Invention Content) Summary of the Invention

[0005] This invention provides a method for preparing a vanadium-modified tungsten oxide-titanium dioxide composite hydrogen-sensitive color-changing material, which mainly solves the problems of poor hydrogen detection effect and environmental impact that prevents repeated use.

[0006] To achieve the aforementioned objective, the present invention provides the following technical solution: A method for preparing a vanadium-modified tungsten oxide-titanium dioxide composite hydrogen-sensitive color-changing material includes the following steps: S1: Add the tungsten source and vanadium source to deionized water and stir to dissolve; S2: Add titanium dioxide, ultrasonically disperse for 10 min, and magnetically stir for 30 min to form a uniform suspension; S3: Dry the suspension in an oven at 80 °C to constant weight; grind the dried sample to make it into fine particles.

[0007] S4: Place the granular sample into a muffle furnace, heat at a rate of 5°C / min, calcine at 500 °C for 3 h, and then naturally cool to obtain WO3–TiO2–V composite powder; S5: Weigh out the noble metal catalyst precursor and dissolve it in deionized water; S6: The powder obtained in S4 is immersed in the solution prepared in S5, stirred evenly, dried at 80 °C, and then calcined at 500 °C to form a hydrogen-sensitive color-changing material.

[0008] Preferably, the tungsten source added in S1 is ammonium metatungstate, ammonium paratungstate, or ammonium tungstate, and the vanadium source is ammonium metavanadate or ammonium orthovanadate.

[0009] Preferably, the molar ratio of vanadium to tungsten in the tungsten source and vanadium source added in S1 is 1% to 5%.

[0010] Preferably, the solid-liquid mass ratio of deionized water added in S1 is 1:(1.2-1.4).

[0011] Preferably, the titanium dioxide added in S2 is anatase titanium dioxide.

[0012] Preferably, the mass of the tungsten source in S2 is 1.12 times the mass of titanium dioxide.

[0013] Preferably, the noble metal catalyst in S5 is chloroplatinic acid, platinum hydroxide, palladium salt, or Pt–Pd bimetallic.

[0014] Preferably, the loading of the noble metal catalyst is 0.1wt% to 1wt%.

[0015] The technical solution provided by this invention has at least the following technical effects: This invention addresses the aforementioned problems by providing a tungsten oxide composite material doped with ammonium metavanadate (NH4VO3) and combined with a supported platinum (Pt) catalyst for hydrogen decomposition, achieving a rapid, strong, and reversible hydrogen-sensitive color-changing response at room temperature. By controlling the WO3 lattice structure and oxygen vacancy concentration through V doping, the hydrogen overflow efficiency and hydrogen intercalation channels are significantly enhanced, enabling the material to achieve a wide detection range from trace amounts to high concentrations of hydrogen at room temperature without the need for external heating or complex instruments. Utilizing supported Pt nanoparticles as catalytic centers fundamentally alters the reaction pathway: Pt drastically lowers the activation energy of hydrogen dissociation, instantly dissociating adsorbed hydrogen molecules into highly reactive atomic hydrogen (H·). These active hydrogen atoms rapidly "overflow" and diffuse into the tungsten oxide lattice to form color centers via the efficient electron transport channels built by the WO3-TiO2 heterostructure. This chemically catalytically driven mechanism allows the material to achieve an ultrafast response of 2-6 seconds at room temperature. This material can be prepared as a thin film, coating, or flexible color-changing tape to achieve large-area, low-cost, visual, and power-free hydrogen leak detection. It is particularly suitable for on-board micro-leakage monitoring of fuel cell vehicles, safety management of hydrogen storage devices, and rapid inspection of hydrogen pipelines. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0018] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. These embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the scope of protection of the present invention is not limited to the following embodiments.

[0019] A method for preparing a vanadium-modified tungsten oxide-titanium dioxide composite hydrogen-sensitive color-changing material includes the following steps: S1: Select ammonium metatungstate and ammonium metavanadate as raw materials. Weigh out ammonium metatungstate and ammonium metavanadate, add deionized water, stir and dissolve. The molar ratio of vanadium to tungsten in ammonium metatungstate and ammonium metavanadate is 1%~5%, and the solid-liquid mass ratio of deionized water is 1:(1.2-1.4).

[0020] S2: Add anatase titanium dioxide, ultrasonically disperse for 10 min, and magnetically stir for 30 min to form a uniform suspension. The mass of ammonium metatungstate in S2 is approximately 1.12 times the mass of titanium dioxide.

[0021] S3: Dry the suspension in an oven at 80 °C to constant weight; grind the dried sample to make it into fine particles.

[0022] S4: Place the granular sample into a muffle furnace, heat at a rate of 5°C / min, calcine at 500°C for 3 h, and then naturally cool to obtain WO3–TiO2–V composite powder.

[0023] S5: Weigh out chloroplatinic acid and dissolve it in deionized water. The loading of the noble metal catalyst Pt is 0.1wt%~1wt%.

[0024] S6: The powder obtained in S4 is immersed in the solution prepared in S5, stirred evenly, dried at 80 °C, and then calcined at 500 °C to form a hydrogen-sensitive color-changing material.

[0025] S7: After passing hydrogen gas through the powder obtained in S6, observe the color change process. Observe the material changing from light gray to dark blue and record its response time.

[0026] Although the embodiments of this invention mainly use chloroplatinic acid (Pt precursor) as an example, those skilled in the art will understand that soluble noble metal salts such as palladium chloride, palladium nitrate, platinum hydroxide, and potassium chloroplatinate can all form highly dispersed noble metal nanoparticles (Pt or Pd) during impregnation and subsequent calcination and reduction processes, following the exact same "hydrogen spillover" catalytic mechanism (i.e., the noble metal dissociates hydrogen molecules, and active hydrogen atoms spill over to the support). Therefore, equivalent substitutions using other noble metal precursors are all covered within the scope of protection of this invention.

[0027] All embodiments of the present invention are prepared using the following general steps, with only the raw material ratios adjusted: First set of examples: Fixed platinum (Pt) content to investigate the effect of vanadium (V) content. In this set of examples, the platinum loading was fixed at 0.3 wt% (i.e., 0.5534 g of chloroplatinic acid solution was added), and only the vanadium doping amount was changed.

[0028] Example 1 (Vanadium-free control group) The molar ratio of V to W was 0%, and the Pt loading was 0.3 wt%. Ammonium metatungstate and ammonium metavanadate were selected as raw materials, and 3.8584 g of ammonium metatungstate ((NH4)2) was weighed. 10 H2W 12 O 410 g of ammonium metavanadate (NH4VO3) and 0 g of xH2O were placed in a 100 ml beaker, and 4.8569 g of deionized water were added. The mixture was sonicated for 3 min to ensure complete dissolution and uniform dispersion of the drug. 3.4513 g of titanium dioxide (TiO2 anatase) was added to the above solution, and the mixture was sonicated for 10 min and magnetically stirred for 30 min to form a uniform suspension. The suspension was sealed and stored at 25 °C for 3 h. The mixture was then dried in an oven at 80 °C to constant weight. The dried sample was ground into fine particles. The dry powder was placed in a muffle furnace and calcined at 500 °C for 3 h at a heating rate of 5 °C / min. After natural cooling, WO3–TiO2–V composite powder was obtained. 0.5534 g of chloroplatinic acid (H2PtCl6·6H2O) was weighed and dissolved in 5.1738 g of deionized water. The mixture was sonicated for 3 min to ensure complete dissolution and uniform dispersion of the drug. The powder was immersed in the solution, stirred until homogeneous, dried at 80 °C, and ground. It was then calcined at 500 °C to form a Pt-supported composite material. Hydrogen gas was introduced into the resulting powder, and the color change process was observed, from light gray to dark blue. The response time was recorded. The color change time was 6 seconds, and the recovery time was 3 seconds.

[0029] Example 2 (Low Vanadium Content) The prepared solution contained 1% V and 0.3 wt% Pt. Ammonium metatungstate and ammonium metavanadate were selected as raw materials, and 3.8198 g of ammonium metatungstate ((NH4)2) was weighed. 10 H2W 12 O 41 0.01832 g of ammonium metavanadate (NH4VO3) and 0.xH2O were placed in a 100 ml beaker, and 4.8695 g of deionized water were added. The mixture was sonicated for 3 min to ensure complete dissolution and uniform dispersion of the drug. 3.4513 g of titanium dioxide (TiO2 anatase) was added to the above solution, and the mixture was sonicated for 10 min and magnetically stirred for 30 min to form a uniform suspension. The suspension was sealed and stored at 25 °C for 3 h. The mixture was then dried in an oven at 80 °C to constant weight. The dried sample was ground into fine particles. The dry powder was placed in a muffle furnace and calcined at 500 °C for 3 h at a heating rate of 5 °C / min. After natural cooling, WO3–TiO2–V composite powder was obtained. 0.5534 g of chloroplatinic acid (H2PtCl6·6H2O) was weighed and dissolved in 5.1738 g of deionized water. The mixture was sonicated for 3 min to ensure complete dissolution and uniform dispersion of the drug. The powder was immersed in the solution, stirred until homogeneous, dried at 80 °C, and ground. It was then calcined at 500 °C to form a Pt-supported composite material. Hydrogen gas was introduced into the resulting powder, and the color change process was observed, from light gray to dark blue. The response time was recorded. The color change time was 5 seconds, and the recovery time was 3 seconds.

[0030] The implementation process of Examples 3 to 5 is the same as that of Example 1, except for the different proportions of tungsten and vanadium added. The implementation data are shown in Table 1. Table 1: Implementation Data Tables for Examples 1 to 5 Second set of examples: Fixed vanadium (V) content, exploring the effect of platinum (Pt) content. In this set of examples, the molar ratio of vanadium to tungsten (V / W) was fixed at 3%, and only the platinum loading was changed.

[0031] Example 6 (Low Platinum Content) Raw material ratio: ammonium metatungstate 3.7426 g, ammonium metavanadate 0.05496 g, titanium dioxide 3.4513 g.

[0032] Catalyst addition: 0.1 wt% chloroplatinic acid solution 0.1782 g.

[0033] Corresponding parameter: V / W molar ratio is approximately 3%.

[0034] Test results: After hydrogen gas was introduced, the color change response time was 10 seconds and the recovery time was 12 seconds.

[0035] The implementation procedures for Examples 7 to 9 are the same as those for Example 2, except for the different loading amounts of the noble metal catalyst Pt. The implementation data are shown in Table 2. Table 2: Implementation Data Tables for Examples 6 to 9 Example 10 (control group palladium) was carried out using the same procedure as Example 2, with Pd as the noble metal catalyst. Raw material ratio: ammonium metatungstate 3.7426 g, ammonium metavanadate 0.05496 g, titanium dioxide 3.4513 g.

[0036] Catalyst addition: 0.3 wt% palladium chloride solution (consistent with the Pt loading in Example 2).

[0037] Corresponding parameter: V / W molar ratio is approximately 3%.

[0038] Test results: After hydrogen gas was introduced, the color change response time was 8 seconds and the recovery time was 5 seconds.

[0039] In summary, this invention achieves significant performance optimization of the tungsten oxide-titanium dioxide composite system by precisely controlling the V doping ratio. Experiments have verified its excellent performance in hydrogen-sensitive color-changing applications, improving the color-changing response time rate and stability, reducing costs and facilitating subsequent product promotion and industrial production, thus demonstrating high industrialization potential.

[0040] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a vanadium-modified tungsten oxide-titanium dioxide composite hydrogen-sensitive color-changing material, characterized in that, Includes the following steps: S1: Add tungsten source and vanadium source to deionized water and stir to dissolve, wherein the molar ratio of vanadium to tungsten in the tungsten source and vanadium source is 1%~3%; S2: Add titanium dioxide, ultrasonically disperse for 10 min, and magnetically stir for 30 min to form a uniform suspension; S3: Place the suspension in an 80 °C oven to dry to constant weight; grind the dried sample to make it into fine particles; S4: Place the granular sample into a muffle furnace, heat at a rate of 5°C / min, calcine at 500 °C for 3 hours, and then cool naturally to obtain WO3–TiO2–V composite powder; S5: Weigh the noble metal catalyst precursor and dissolve it in deionized water. The noble metal catalyst is chloroplatinic acid, platinum hydroxide, palladium salt, or Pt–Pd bimetallic. S6: The powder obtained in S4 is impregnated in the solution prepared in S5, stirred evenly, dried at 80 °C, and then calcined at 500 °C to form a hydrogen-sensitive color-changing material, wherein the loading of the noble metal catalyst is 0.3 wt%~0.5 wt%.

2. The preparation method of the vanadium-modified tungsten oxide-titanium dioxide composite hydrogen-sensitive color-changing material according to claim 1, characterized in that, The tungsten source is ammonium metatungstate, ammonium paratungstate, or ammonium tungstate, and the vanadium source is ammonium metavanadate or ammonium orthovanadate.

3. The preparation method of the vanadium-modified tungsten oxide-titanium dioxide composite hydrogen-sensitive color-changing material according to claim 1, characterized in that, The solid-liquid mass ratio of deionized water added in S1 is 1:(1.2-1.4).

4. The preparation method of a vanadium-modified tungsten oxide-titanium dioxide composite hydrogen-sensitive color-changing material according to claim 1, characterized in that, The titanium dioxide added in S2 is anatase titanium dioxide.

5. The preparation method of a vanadium-modified tungsten oxide-titanium dioxide composite hydrogen-sensitive color-changing material according to claim 1, characterized in that, In step S2, the mass of the tungsten source is 1.12 times the mass of the titanium dioxide.

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