WO3 nanowire electrochromic capacitance film and preparation method thereof
Bi-WO3 seed layers were prepared by sol-gel spin coating and solvothermal method, which solved the problem of insufficient adhesion between nanostructures and substrates. This resulted in a WO3 nanowire electrochromic capacitor film with high transmittance and fast response, which is suitable for building energy conservation and dynamic light control. It also has good cycle stability and low cost.
Patent Information
- Application Number
- CN202511511032.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-22
- Publication Date
- 2026-01-16
AI Technical Summary
In existing technologies, the adhesion between the WO3 nanostructure prepared by hydrothermal method and the substrate is insufficient, resulting in a 40% performance degradation after 1000 cycles. Furthermore, the preparation of high-precision nanoarrays is costly and difficult to scale up.
A Bi-WO3 seed layer was prepared by spin-coating a sol-gel process and a solvothermal method using bismuth-doped peroxytungstic acid sol onto a conductive glass substrate and followed by calcination. Subsequently, a solvothermal reaction was carried out in a tungsten source solvothermal solution to form a WO3 nanowire electrochromic capacitor film.
The prepared WO3 nanowire electrochromic capacitor film has excellent electrochromic and capacitive properties, rapid and reversible transitions from transparent to deep blue, and a performance retention rate of over 60% after 70,000 cycles, making it suitable for building energy-saving smart windows and dynamic light control devices.
Smart Images
Figure CN121348623A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrochromic and energy storage materials technology, specifically relating to a WO3 nanowire electrochromic capacitor film and its preparation method. Background Technology
[0002] Buildings consume 20-40% of the world's primary energy, most of which is used for cooling, heating, lighting, and appliances. Approximately 30% of this energy is lost through windows. Therefore, developing smart materials with both light modulation and energy storage functions has become a core direction for building energy conservation. Electrochromic materials achieve optical modulation through ion insertion / extraction, and the energy storage mechanism of supercapacitors essentially relies on the same ion migration process. This shared mechanism has driven research on tungsten trioxide (WO3)-based bifunctional materials. When ions are inserted into the WO3 lattice, charge storage is achieved simultaneously with changes in visible light transmittance. Nanostructured WO3 significantly enhances bifunctional performance due to its unique morphology: three-dimensional porous nanowire arrays increase the material's specific surface area, providing abundant sites for ion storage and significantly improving areal capacitance; during ion insertion, the directional growth of nanowires shortens the electrochromic response time to less than 5 seconds. Current research shows that vertically oriented nanoarrays can simultaneously achieve 75% optical modulation and 50 mF / cm². 2 The surface capacitance exhibits a synergistic enhancement effect between electrochromism and energy storage. Current technological bottlenecks include: insufficient adhesion between the hydrothermal nanostructures and the substrate, resulting in a 40% performance degradation after 1000 cycles; and the reliance on complex processes such as vacuum sputtering for high-precision nanoarrays, which are costly and difficult to scale up. Therefore, achieving controllable growth of nano-WO3 through structural design and process innovation is crucial for the industrialization of WO3 bifunctional materials. Summary of the Invention
[0003] The first objective of this invention is to provide a method for preparing WO3 nanowire electrochromic capacitor films to solve the technical problem that the adhesion between the nanostructures prepared by hydrothermal method and the substrate is insufficient, and the performance degrades by 40% after 1000 cycles.
[0004] The second objective of this invention is to provide a WO3 nanowire electrochromic capacitor film.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0006] A method for preparing a WO3 nanowire electrochromic capacitor film includes the following steps:
[0007] S1: Dissolve tungstic acid in hydrogen peroxide to obtain peroxytungstic acid solution;
[0008] S2: Add a bismuth-containing substance to the peroxytungstic acid solution and heat until the bismuth-containing substance is completely dissolved to obtain bismuth-doped peroxytungstic acid sol.
[0009] S3: Bismuth-doped peroxytungstic acid sol is spin-coated onto a conductive glass substrate to form a film, and then calcined to obtain a bismuth-doped WO3 seed layer film.
[0010] S4: Dissolve the tungsten source in a solvent to obtain a solvothermal solution containing the tungsten source. Place the bismuth-doped WO3 seed layer film into the solvothermal solution containing the tungsten source for a solvothermal reaction, and then calcine to obtain a WO3 nanowire electrochromic capacitor film.
[0011] Furthermore, the concentration of the peroxytungstic acid solution mentioned in S1 is 0.1–1 M.
[0012] Furthermore, in the bismuth-doped peroxytungstic acid sol described in S2, the ratio of bismuth atoms to tungsten atoms is 1:10 to 1:100.
[0013] Furthermore, the bismuth-containing substance mentioned in S2 is one or more of metallic bismuth powder, bismuth chloride, bismuth nitrate pentahydrate, and bismuth oxide; the heating method for heating until the bismuth-containing substance is completely dissolved is water bath heating, and the heating temperature is 40-100℃.
[0014] Furthermore, the spin coating speed described in S3 is 1500–3500 rpm, the spin coating time is 20–45 s, and the number of spin coatings is 1–5.
[0015] Furthermore, the tungsten source in S4 is one or more of metallic tungsten powder, sodium tungstate, calcium tungstate, ammonium tungstate, tungstic acid, tungsten hexafluoride, and tungsten hexachloride; the solvent is ethanol; and the concentration of the solvothermal solution containing the tungsten source is 1–100 mg / mL.
[0016] Furthermore, the temperature of the solvothermal reaction described in S4 is 80–180°C, and the reaction time is 1–10 h.
[0017] Furthermore, the calcination temperature in S3 and S4 is 50–500℃, and the calcination time is 1–10 h.
[0018] A WO3 nanowire electrochromic capacitor film was prepared using the above-mentioned method for preparing WO3 nanowire electrochromic capacitor films.
[0019] The beneficial effects of this invention are:
[0020] The WO3 nanowire electrochromic capacitor film of this invention is a three-dimensional nanostructure with uniform growth and distribution, exhibiting excellent electrochromic properties. It can achieve rapid and reversible transitions between transparent and deep blue colors under different voltages, and possesses excellent capacitance performance, demonstrating dual-functionality. Using a 0.5M mixed solution of H2SO4 and AlCl3 as the electrolyte, the WO3 nanowire electrochromic capacitor film of this invention achieves a transmittance change of up to 80% at a wavelength of 633 nm, with coloring and fading times of 3.3 s and 2.7 s, respectively, and an areal capacitance of 78.15 mF / cm². 2 The WO3 nanowire electrochromic capacitor film prepared by this invention maintains stability after more than 70,000 cycles of testing. It combines high transmittance with rapid response characteristics, making it suitable for applications such as energy-efficient smart windows in buildings and dynamic light control devices.
[0021] The WO3 nanowire electrochromic capacitor film of this invention exhibits a performance retention rate of over 60% after 70,000 fading cycles, demonstrating significant cycling stability advantages. The core reason lies in the synergistic effect of three aspects: First, Bi doping forms Bi-OW bonds, which enhances the WO3 lattice toughness, suppresses lattice distortion during ion insertion, and improves the interfacial adhesion between the film and the FTO substrate, preventing detachment or microcracks. Second, the three-dimensional nanowire structure provides a buffer space for ion insertion / extraction due to its high porosity, while the one-dimensional growth direction of the nanowires shortens the ion diffusion distance and accelerates transport. Third, the fabrication process of this invention can form a dense array, improving the hexagonal crystallinity, reducing lattice distortion and structural collapse. Combined with the bifunctional synergistic effect and the mixed electrolyte, this further reduces the lattice expansion rate, achieving improved stability.
[0022] This invention employs a sol-gel spin coating process and a solvothermal method, eliminating the need for vacuum equipment and simplifying the operation process, making it suitable for large-scale production. Furthermore, the raw materials used in this invention are low-cost, primarily employing common chemicals such as tungstic acid, hydrogen peroxide, and bismuth oxide. The Bi-PTA sol can be stored at room temperature for several months without deterioration or precipitation, reducing preparation costs and storage difficulties, which is beneficial for practical production applications.
[0023] The WO3 nanowire electrochromic capacitor film of this invention exhibits high transmittance and transparency in the faded state, and displays a deep blue color in the colored state, demonstrating strong shielding ability against visible light. It exhibits extremely fast response in a mixed solution of sulfuric acid and aluminum chloride, good areal capacitance at appropriate current densities, and good cycling stability within a suitable potential window, giving it a comparative advantage over previously reported products. Attached Figure Description
[0024] Figure 1 This is a scanning electron microscope image of the WO3 nanowire electrochromic capacitor film in Example 1;
[0025] Figure 2The transmittance curves of the WO3 nanowire electrochromic capacitor film in Example 1 are shown in the original state, the -0.5V colored state, and the 0.5V faded state.
[0026] Figure 3 The image shows the in-situ response curves of the WO3 nanowire electrochromic capacitor film in Example 1 at potentials of -0.5 / 0.5V.
[0027] Figure 4 The graph shows the long-term stability test curves of the WO3 nanowire electrochromic capacitor film in Example 1 at potentials of -0.5 / 0.5V.
[0028] Figure 5 This is a charge-discharge curve of the WO3 nanowire electrochromic capacitor film in Example 1. Detailed Implementation
[0029] The present invention will be further described below with reference to the embodiments and accompanying drawings.
[0030] Example 1
[0031] The preparation method of the WO3 nanowire electrochromic capacitor film in Example 1 includes the following steps:
[0032] (1) Pretreatment of fluorine-doped tin oxide (FTO) glass substrate
[0033] A piece of FTO glass (3cm×2cm) was ultrasonically cleaned for 15 minutes each with deionized water, anhydrous ethanol, and deionized water to remove organic matter from the surface and blow away the liquid.
[0034] (2) Preparation of Bi-PTA sol
[0035] 15g of tungstic acid (H2WO4) was dissolved in 100mL of 30% hydrogen peroxide (H2O2) and stirred at 300rpm for 4 days at room temperature. After standing for 6 hours, a clear and transparent peroxytungstic acid (PTA) solution was obtained. Bismuth oxide (Bi2O3) was added to the PTA solution to make the ratio of Bi atoms to W atoms in the solution 1:20. The solution was then sealed and heated in a water bath at 70℃ for 9 hours until Bi2O3 was completely dissolved to obtain bismuth-doped peroxytungstic acid sol (Bi-PTA sol).
[0036] (3) Preparation of Bi-WO3 seed layer thin film
[0037] The Bi-PTA sol obtained in step (2) was spin-coated on an FTO glass substrate at a speed of 3000 rpm for 40 s to form a film. After spin-coating once, the film was calcined at 300℃ for 4 h to obtain a bismuth-doped WO3 (Bi-WO3) seed layer film.
[0038] (4) Preparation of WO3 nanowire electrochromic capacitor film
[0039] Add 0.5g of tungsten hexachloride, 0.03g of ammonium tungstate, and 50mL of anhydrous ethanol to a polytetrafluoroethylene liner and stir until the solution turns deep blue. Place the Bi-WO3 seed layer film obtained in step (3) into the liner, place it in a reaction vessel, and bake it at 160℃ for 8h. After cooling, calcine the obtained film sample at 250℃ for 4h to obtain the WO3 nanowire electrochromic capacitor film.
[0040] Example 2
[0041] The preparation method of the WO3 nanowire electrochromic capacitor film in Example 2 includes the following steps:
[0042] (1) Pretreatment of FTO glass substrate
[0043] A piece of FTO glass (3cm×2cm) was ultrasonically cleaned for 15 minutes each with deionized water, anhydrous ethanol, and deionized water to remove organic matter from the surface and blow away the liquid.
[0044] (2) Preparation of Bi-PTA sol
[0045] 15g of H2WO4 was dissolved in 100mL of 30% H2O2 and stirred at 300rpm for 4 days at room temperature. After standing for 6 hours, a clear and transparent peroxytungstic acid solution was obtained. Bismuth oxide was added to the PTA solution to make the ratio of Bi atoms to W atoms in the solution 1:50. The solution was then sealed and heated in a water bath at 70℃ for 9 hours until Bi2O3 was completely dissolved to obtain Bi-PTA sol.
[0046] (3) Preparation of Bi-WO3 seed layer thin film
[0047] The Bi-PTA sol obtained in step (2) was spin-coated on an FTO glass substrate at a speed of 3000 rpm for 40 s to form a film. The spin coating was repeated twice, and then the film was calcined at 300℃ for 4 h to obtain a Bi-WO3 seed layer film.
[0048] (4) Preparation of WO3 nanowire electrochromic capacitor film
[0049] Add 0.5g of tungsten hexachloride, 0.03g of ammonium tungstate, and 50mL of anhydrous ethanol to a polytetrafluoroethylene liner and stir until the solution turns deep blue. Place the Bi-WO3 seed layer film obtained in step (3) into the liner, place it in a reaction vessel, and bake it at 160℃ for 8h. After cooling, calcine the obtained film sample at 250℃ for 4h to obtain the WO3 nanowire electrochromic capacitor film.
[0050] Example 3
[0051] The preparation method of the WO3 nanowire electrochromic capacitor film in Example 3 includes the following steps:
[0052] (1) Pretreatment of FTO glass substrate
[0053] A piece of FTO glass (3cm×2cm) was ultrasonically cleaned for 15 minutes each with deionized water, anhydrous ethanol, and deionized water to remove organic matter from the surface and blow away the liquid.
[0054] (2) Preparation of Bi-PTA sol
[0055] 15g of H2WO4 was dissolved in 100mL of 30% H2O2 and stirred at 300rpm for 4 days at room temperature. After standing for 6 hours, a clear and transparent peroxytungstic acid solution was obtained. Bismuth oxide was added to the PTA solution to make the ratio of Bi atoms to W atoms in the solution 1:20. The solution was then sealed and heated in a water bath at 90℃ until Bi2O3 was completely dissolved to obtain Bi-PTA sol.
[0056] (3) Preparation of Bi-WO3 seed layer thin film
[0057] The Bi-PTA sol obtained in step (2) was spin-coated on an FTO glass substrate at a speed of 2000 rpm for 35 s to form a film. The spin coating was repeated 3 times, and then the film was calcined at 300℃ for 3 h to obtain a Bi-WO3 seed layer film.
[0058] (4) Preparation of WO3 nanowire electrochromic capacitor film
[0059] Add 0.5g of tungsten hexachloride, 0.03g of ammonium tungstate, and 50mL of anhydrous ethanol to a polytetrafluoroethylene liner and stir until the solution turns deep blue. Place the Bi-WO3 seed layer film obtained in step (3) into the liner, place it in a reaction vessel, and bake it at 180℃ for 6h. After cooling, calcine the obtained film sample at 250℃ for 4h to obtain the WO3 nanowire electrochromic capacitor film.
[0060] Experimental Example 1
[0061] Using the WO3 nanowire electrochromic capacitor film from Example 1 as the working electrode, a platinum sheet as the counter electrode, and saturated Ag / AgCl as the reference electrode, and a 0.5M mixed solution of H2SO4 and AlCl3 as the electrolyte, the electrochromic and capacitive performance were tested using a three-electrode electrochemical workstation and a UV-Vis-NIR spectrophotometer. The test results are as follows: Figures 2-5 As shown. From Figure 2It can be seen that the WO3 nanowire electrochromic capacitor film prepared in Example 1, using a 0.5M H2SO4 and AlCl3 mixed solution as the electrolyte and a wavelength of 633nm, exhibits a transmittance variation of up to 80% between the -0.5V colored state and the 0.5V faded state, demonstrating a wide optical modulation range. Figure 3 It can be seen that the WO3 nanowire electrochromic capacitor film prepared in Example 1 has a very short fading and coloring time, with coloring and fading times of 3.3 s and 2.7 s, respectively. Figure 4 It can be seen that the WO3 nanowire electrochromic capacitor film prepared in Example 1 retains 60% of its performance in over 70,000 fading cycles, demonstrating good long-term stability. Figure 5 It can be seen that the charge-discharge curves of the WO3 nanowire electrochromic capacitor film prepared in Example 1 have good symmetry, exhibit excellent reversibility in terms of capacitance, small polarization and fast ion diffusion rate during the charge-discharge process, and possess high charge-discharge efficiency and good kinetic performance, with a capacitance of 1 mA / cm². 2 It still has 78.15 mF / cm at the current density. 2 The area capacitance, while at 2mA / cm 2 It still has 67.3 mF / cm at the current density. 2 The area capacitance exhibits excellent rate performance.
[0062] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.
[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent structural changes made based on the content of the present invention's specification shall also be included within the scope of protection of the present invention.
Claims
1. A method for preparing a WO3 nanowire electrochromic capacitor film, characterized in that, Includes the following steps: S1: Dissolve tungstic acid in hydrogen peroxide to obtain peroxytungstic acid solution; S2: Add a bismuth-containing substance to the peroxytungstic acid solution and heat until the bismuth-containing substance is completely dissolved to obtain bismuth-doped peroxytungstic acid sol. S3: Bismuth-doped peroxytungstic acid sol is spin-coated onto a conductive glass substrate to form a film, and then calcined to obtain a bismuth-doped WO3 seed layer film. S4: Dissolve the tungsten source in a solvent to obtain a solvothermal solution containing the tungsten source. Place the bismuth-doped WO3 seed layer film into the solvothermal solution containing the tungsten source for a solvothermal reaction, and then calcine to obtain a WO3 nanowire electrochromic capacitor film.
2. The method for preparing the WO3 nanowire electrochromic capacitor film according to claim 1, characterized in that, The concentration of the peroxytungstic acid solution mentioned in S1 is 0.1–1 M.
3. The method for preparing the WO3 nanowire electrochromic capacitor film according to claim 1, characterized in that, The ratio of bismuth atoms to tungsten atoms in the bismuth-doped peroxytungstic sol described in S2 is 1:10 to 1:
100.
4. The method for preparing the WO3 nanowire electrochromic capacitor film according to claim 1, characterized in that, The bismuth-containing substance mentioned in S2 is one or more of metallic bismuth powder, bismuth chloride, bismuth nitrate pentahydrate, and bismuth oxide; the heating method for heating until the bismuth-containing substance is completely dissolved is water bath heating, and the heating temperature is 40-100℃.
5. The method for preparing the WO3 nanowire electrochromic capacitor film according to claim 1, characterized in that, The spin coating speed described in S3 is 1500-3500 rpm, the spin coating time is 20-45 s, and the number of spin coatings is 1-5.
6. The method for preparing the WO3 nanowire electrochromic capacitor film according to claim 1, characterized in that, The tungsten source mentioned in S4 is one or more of the following: metallic tungsten powder, sodium tungstate, calcium tungstate, ammonium tungstate, tungstic acid, tungsten hexafluoride, and tungsten hexachloride; the solvent is ethanol; and the concentration of the solvothermal solution containing the tungsten source is 1–100 mg / mL.
7. The method for preparing the WO3 nanowire electrochromic capacitor film according to claim 1, characterized in that, The temperature of the solvothermal reaction described in S4 is 80–180°C, and the reaction time is 1–10 h.
8. The method for preparing the WO3 nanowire electrochromic capacitor film according to claim 1, characterized in that, The roasting temperature in S3 and S4 is 50–500℃, and the roasting time is 1–10 h.
9. A WO3 nanowire electrochromic capacitor film, characterized in that, The WO3 nanowire electrochromic capacitor film was prepared using the preparation method described in any one of claims 1 to 8.