A dual-ion modified Bi2WO6 electrochromic thin film material and a preparation method thereof
By employing a dual-ion modified Bi2WO6 electrochromic film preparation method, the problem of small optical modulation amplitude of Bi2WO6 electrochromic films was solved, achieving excellent electrochromic performance in the near-infrared band and low-cost preparation, thus broadening the application fields.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 浙江大学宁波国际科创中心
- Filing Date
- 2024-04-22
- Publication Date
- 2026-07-28
AI Technical Summary
Existing Bi2WO6 electrochromic films have small optical modulation amplitudes, and their preparation methods are costly and require sophisticated equipment, which limits their application and promotion.
Bi2WO6 nanoparticles were prepared by a one-step hydrothermal method, and the Bi2WO6 lattice structure was modified by a dual-ion substitution reaction of hydrogen ions and alkali metal ions to prepare a dual-ion modified Bi2WO6 electrochromic film, which increased the specific surface area and loose porous structure, thereby improving the electrochromic performance.
It achieves excellent electrochromic performance in the near-infrared band, significantly increases the optical modulation amplitude, broadens the application field, and has a simple preparation method, low cost, and is easy to promote on a large scale.
Smart Images
Figure CN118373606B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electrochromic thin films, specifically to a dual-ion modified Bi2WO6 electrochromic thin film material and its preparation method. Background Technology
[0002] Electrochromic glass, also known as smart windows, is a key technology for energy conservation and emission reduction in modern buildings. It dynamically adjusts the transmittance of solar radiation based on external lighting conditions and human comfort needs, significantly reducing the load on building lighting, heating, ventilation, and air conditioning. Compared to static energy-saving glass (such as insulated glass or low-emissivity glass), it offers superior energy-saving performance and adaptive adjustment capabilities, making it highly favored by the market. Tungsten trioxide (WO3) has received widespread attention and extensive research for many years due to its excellent color-changing properties, wide availability of raw materials, simple preparation methods, and low cost, and has successfully entered industrial applications. Although tungsten trioxide has broad application prospects in the field of electrochromic glass, the current preparation methods are mainly based on magnetron sputtering. The high cost of equipment and the high-vacuum coating environment increase production costs, which to some extent limits its application and promotion. Furthermore, the limited variety of electrochromic materials, the difficulty in controlling the structure, and the need for further improvement in electrochromic performance severely restrict the application and development of the electrochromic field.
[0003] Tungstates, as an important class of multifunctional inorganic materials, have shown great application value and research interest in the field of electrochromic technology. Their unique self-activated luminescence effect, gas-sensitive properties, and optical and microwave properties enable their wide application in fields such as smart dimming, display technology, microwave ceramics, and catalysis. Furthermore, tungstates are relatively simple to synthesize, abundant in reserves, low in cost, and low in toxicity, meeting the current demand for environmentally friendly materials. By controlling the voltage, tungstates can achieve color changes from transparent to blue, purple, and other colors while maintaining a stable chemical structure and good cycling stability. This wide-range, efficient light modulation capability facilitates dynamic adjustment of light intensity and broadens the application prospects of tungstates in novel low-energy smart windows, display technology, and energy-related fields.
[0004] Bismuth tungstate (Bi₂WO₆), a typical bismuth layered tungstate, is a narrow-bandgap n-type semiconductor composed of alternating bismuth-oxygen layers and tungsten-oxygen layers. [Bi₂O₂] 2+Covalent meshes, located between two-dimensional perovskite plates, with layered structures bridged by shared oxygen atoms, are widely used in environmental pollution control, photocatalysis, and optoelectronic materials. In the field of electrochromism, by soft chemically treating the layered structure of Bi₂WO₆, the bismuth oxide layer is selectively leached, allowing smaller protons and metal ions to penetrate the interlayer. This preserves the loose, layered structure of the precursor, facilitating uniform charge distribution on the material's surface and within, while simultaneously increasing the specific surface area. This provides more channels and reaction sites for ions, promoting rapid ion insertion and extraction, thereby enhancing electrochromic performance.
[0005] Currently, research on tungstate compounds as electrochromic building blocks for the preparation of chromatic materials and thin films is increasing. Existing literature (Kishimoto.F, Takanabe, K. Electron Storage in Monolayer Tungstate Nanosheets Produced via a Scalable Exfoliation Method[J].The Journal of Physical Chemistry Letters,2024,15:3509-3515.) has shown that monolayer WO3 nanosheets were prepared by exfoliating the bismuth layered tungstate H2W2O7. The crystalline WO3 nanosheets exhibited electron enrichment, and the colloidal nanosheets generated by exfoliation provide a convenient way to prepare tungsten-based thin films and nanostructured materials. Another study (Wang R, Sun Y, Brady A, et al. Fast proton insertion in layered H2W2O7 via selective etching of anaurivillius phase[J]. Advanced Energy Materials, 2021, 11(1): 2003335.) synthesized H2W2O7 from bismuth layered tungstate Bi2W2O9, and the results showed that H2W2O7 exhibited reversible multicolor electrochromic effects with changes in proton content. However, the above studies only focused on the synthesis of H2W2O7 from the Bi2W2O9 precursor phase, and there are currently no reports on biionic modification of Bi2WO6, nor are there any reports on the application of modified tungsten-based nanostructures in the field of electrochromism. Summary of the Invention
[0006] To address the shortcomings of existing technologies, this invention aims to provide a dual-ion modified Bi2WO6 electrochromic thin film material and its preparation method. The method is simple to operate, safe and controllable, and low in cost. By modifying the Bi2WO6 lattice structure through a dual-ion substitution reaction of hydrogen ions and alkali metal ions, the technical problem of small optical modulation amplitude in existing Bi2WO6 electrochromic thin films is solved, resulting in a dual-ion modified Bi2WO6 electrochromic thin film exhibiting excellent electrochromic performance in the near-infrared band.
[0007] The objective of this invention is achieved through the following technical solution: a method for preparing a dual-ion modified Bi2WO6 electrochromic thin film material, comprising the following steps:
[0008] (1) Bi2WO6 was prepared by a one-step hydrothermal method. After the reaction was completed, deionized water and ethanol were added respectively, centrifuged, washed and dried to obtain Bi2WO6 nanopowder.
[0009] (2) The Bi2WO6 nanopowder prepared in step (1) is mixed with nitrate and hydrochloric acid solution at a molar ratio of 1:1 to 1:4. The mixture is stirred at 60 to 120°C for 24 to 96 hours. After the reaction is completed, deionized water and ethanol are added and centrifuged to wash the powder sample. The washing liquid is removed and the powder sample is dried to obtain the bi-ion modified Bi2WO6 nanopowder.
[0010] (3) The nanoparticles of Bi2WO6 modified by dual ions prepared in step (2) are dispersed in isopropanol and ultrasonically dispersed to obtain a dispersion. The dispersion is then spin-coated onto the surface of a conductive substrate and annealed at 350°C to obtain an electrochromic film.
[0011] Furthermore, in step (1), the hydrothermal reaction conditions are 140–200°C for 12–24 hours.
[0012] Further, in step (2), the nitrate powder includes one or more of aluminum nitrate, zinc nitrate, copper nitrate, nickel nitrate, iron nitrate, manganese nitrate, lithium nitrate, sodium nitrate, and potassium nitrate.
[0013] Furthermore, in step (2), the concentration of the hydrochloric acid solution is 6–12 mol / L.
[0014] Furthermore, in step (2), when the hydrochloric acid solution is replaced with a nitric acid solution, the concentration of the nitric acid solution is 8-16 mol / L.
[0015] Furthermore, in step (2), the pH of the washing solution is less than 7.
[0016] Furthermore, in step (3), the ratio of isopropanol to Bi2WO6 powder is 5mL:0.25~0.5g.
[0017] Furthermore, in step (3), the conductive substrate is FTO or ITO conductive glass, or other transparent conductive substrate material.
[0018] Furthermore, in step (3), the method of preparing the film is replaced by spraying, scraping or inkjet printing.
[0019] The present invention also provides a bi-ion modified Bi2WO6 electrochromic thin film material prepared according to the above-described method for preparing bi-ion modified Bi2WO6 electrochromic thin film material.
[0020] Compared to the unmodified Bi2WO6 electrochromic film, the Bi2WO6 electrochromic film obtained through dual-ion modification retains the original layered crystal structure of Bi2WO6. By replacing the bismuth-oxygen layer structural units with smaller-radius hydrogen ions and alkali metal ions, while preserving the tungsten-oxygen layer structural units, the resulting film exhibits a loose and porous surface structure. This increases the specific surface area of the film, shortens the ion diffusion path, and facilitates rapid ion insertion / extraction reactions, thereby improving the electrochromic performance of the dual-ion modified Bi2WO6 electrochromic film.
[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0022] (1) The present invention can controllably prepare Bi2WO6 nanoparticles by hydrothermal method, and then modify the Bi2WO6 lattice structure by hydrogen ions and alkali metal ions to perform a double ion replacement reaction on the Bi2WO6 nanoparticles. Finally, the Bi2WO6 nanoparticles are dispersed and ultrasonically spin-coated on a transparent conductive substrate to obtain an electrochromic thin film material. The obtained double ion modified Bi2WO6 electrochromic thin film exhibits excellent electrochromic performance in the near-infrared band and the optical modulation amplitude is greatly increased.
[0023] (2) Compared with the unmodified Bi2WO6 electrochromic film material, the electrochromic film material of the present invention retains the key structural features of the precursor phase through soft chemical modification, solves the defects such as small light modulation amplitude of Bi2WO6 electrochromic film, exhibits excellent electrochromic behavior, and broadens the application field.
[0024] (3) The electrochromic thin film prepared by the present invention is simple to prepare, has low preparation cost, low equipment requirements, is safe and controllable, and the product is easy to be promoted on a large scale. Attached Figure Description
[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, 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.
[0026] Figure 1 This is a schematic diagram of the preparation process in Example 1 of the present invention;
[0027] Figure 2 The XRD patterns are of the products of Embodiment 1, Embodiment 2, Comparative Example 1, and Comparative Example 2 of the present invention;
[0028] Figure 3 The images shown are SEM images of the products from Embodiment 1, Embodiment 2, Comparative Example 1, and Comparative Example 2 of the present invention; wherein, Figure 3 Image (A) in the image is a SEM image of the Bi2WO6 nanoparticles prepared in Comparative Example 1. Figure 3 Image (B) in the image is a SEM image of the hydrogen ion-modified Bi2WO6 nanoparticles prepared in Comparative Example 2. Figure 3 Image (C) in the image is a SEM image of the hydrogen ion and aluminum ion modified Bi2WO6 nanoparticles prepared in Example 1. Figure 3 (D) in the image is a SEM image of the hydrogen ion and zinc ion modified Bi2WO6 nanoparticles prepared in Example 2;
[0029] Figure 4 These are HRTEM images of the products of Embodiment 1 and Comparative Example 1 of the present invention; wherein, Figure 4 Image (A) in the image is an HRTEM image of Bi2WO6 nanoparticles prepared in Comparative Example 1. Figure 4 (B) is the HRTEM image of the hydrogen ion and aluminum ion modified Bi2WO6 nanoparticles prepared in Example 1;
[0030] Figure 5 This is a graph showing the transmittance variation of the product of Comparative Example 1 under different voltages.
[0031] Figure 6 This is a graph showing the transmittance variation of the product of Comparative Example 2 under different voltages.
[0032] Figure 7 This is a graph showing the transmittance variation of the product of Embodiment 1 of the present invention under different voltages;
[0033] Figure 8 This is a graph showing the transmittance variation of the product in Embodiment 2 of the present invention under different voltages;
[0034] Figure 9The cyclic voltammetry curves are for the products of Embodiment 1, Embodiment 2, Comparative Example 1, and Comparative Example 2 of the present invention. Detailed Implementation
[0035] To enable those skilled in the art to better understand the technical solutions of the present invention, and to make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the manufacturer. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.
[0036] Example 1:
[0037] (1) Preparation of Bi2WO6 nanopowder;
[0038] See Figure 1 1.98 g of sodium tungstate dihydrate and 2.91 g of bismuth nitrate pentahydrate were mixed and dissolved in 200 mL of deionized water. The mixture was placed in an ultrasonic bath for 30 min to complete the precipitate reaction. The supernatant was removed, and the precipitate was washed three times with deionized water. The washing solution was then added to a 50 mL high-pressure reactor lined with polytetrafluoroethylene to carry out a hydrothermal reaction at 180 °C for 20 h. The reaction product was centrifuged, washed with deionized water and ethanol, and dried to obtain Bi2WO6 nanoparticles.
[0039] (2) The prepared Bi2WO6 nanopowder was modified with hydrogen ions and aluminum ions;
[0040] 872.5 mg of Bi2WO6 nanoparticles prepared in step (1) were weighed, and 469 mg of aluminum nitrate nonahydrate was dissolved in 50 mL of 6 mol / L HCl solution. The mixture was heated and stirred at 120 °C for 72 h at a speed of 900 rpm to modify the Bi2WO6 nanoparticles with hydrogen ions and aluminum ions. After stirring, deionized water and ethanol were added and centrifuged to wash the mixture, and the precipitate was obtained. The precipitate was then dried in a 60 °C oven for 12 h to obtain Bi2WO6 nanoparticles modified with hydrogen ions and aluminum ions.
[0041] (3) 0.375 g of Bi2WO6 nanoparticles modified with hydrogen ions and aluminum ions were dispersed in 5 mL of isopropanol and sonicated for 60 min to obtain a dispersion. FTO conductive glass (30 mm × 30 mm × 2.2 mm) was ultrasonically cleaned with deionized water and ethanol and then placed in an oven to dry. After drying, it was placed in a surface plasma cleaner and cleaned under the conditions of working power of 60 W, working pressure of 100 kPa and working time of 2 min. The electrochromic solution prepared in step (2) was continuously spin-coated on the surface of FTO glass in three steps. The first step was spin-coated at 800 r / s for 30 s, the second step was spin-coated at 1600 r / s for 30 s, and the third step was spin-coated at 2000 r / s for 30 s. After that, it was annealed at 350 °C for 30 min to obtain the double ion modified Bi2WO6 electrochromic film.
[0042] Example 2:
[0043] (1) Preparation of B i2 WO6 nanoparticles;
[0044] 1.98 g of sodium tungstate dihydrate and 2.91 g of bismuth nitrate pentahydrate were mixed and dissolved in 200 mL of deionized water. The mixture was placed in an ultrasonic bath for 30 min to complete the precipitate reaction. The supernatant was removed, and the precipitate was washed three times with deionized water. The washing solution was then added to a 50 mL high-pressure reactor lined with polytetrafluoroethylene for hydrothermal reaction. The hydrothermal reaction conditions were 180 °C for 20 h. The reaction product was washed and dried by centrifugation with deionized water and ethanol to obtain Bi2WO6 nanoparticles.
[0045] (2) The prepared Bi2WO6 nanopowder was modified with hydrogen ions and zinc ions;
[0046] 872.5 mg of Bi2WO6 nanoparticles prepared in step (1) were weighed, and 371.9 mg of zinc nitrate hexahydrate was dissolved in 50 mL of 6 mol / L HCl solution. The mixture was heated and stirred at 120 °C for 72 h at a speed of 900 rpm to modify the Bi2WO6 nanoparticles with hydrogen ions and zinc ions. After stirring, deionized water and ethanol were added and centrifuged to wash the mixture, and the precipitate was obtained. The precipitate was then dried in a 60 °C oven for 12 h to obtain the Bi2WO6 nanoparticles modified with hydrogen ions and zinc ions.
[0047] (3) 0.375g of Bi2WO6 nanoparticles modified with hydrogen ions and zinc ions were dispersed in 5mL of isopropanol and ultrasonicated for 60min to obtain a dispersion solution; FTO conductive glass (30mm×30mm×2.2mm) was ultrasonically cleaned with deionized water and ethanol and then placed in an oven to dry. After drying, it was placed in a surface plasma cleaner and cleaned under the conditions of working power of 60W, working pressure of 100kPa and working time of 2min; the electrochromic solution prepared in step (2) was continuously spin-coated on the surface of FTO glass in three steps. The first step was spin-coated at 800r / s for 30s, the second step was spin-coated at 1600r / s for 30s, and the third step was spin-coated at 2000r / s for 30s. After that, it was annealed at 350℃ for 30min to obtain the double ion modified Bi2WO6 electrochromic film.
[0048] Comparative Example 1:
[0049] (1) Preparation of Bi2WO6 nanopowder;
[0050] 1.98 g of sodium tungstate dihydrate and 2.91 g of bismuth nitrate pentahydrate were mixed and dissolved in 200 mL of deionized water. The mixture was placed in an ultrasonic bath for 30 min to complete the precipitate reaction. The supernatant was removed, and the precipitate was washed three times with deionized water. The washing solution was then added to a 50 mL high-pressure reactor lined with polytetrafluoroethylene for hydrothermal reaction. The hydrothermal reaction conditions were 180 °C for 20 h. The reaction product was washed and dried by centrifugation with deionized water and ethanol to obtain Bi2WO6 nanoparticles.
[0051] (2) Disperse 0.375g of Bi2WO6 nanoparticles prepared in step (1) in 5mL of isopropanol and sonicate for 60min to obtain a dispersion; clean FTO conductive glass (30mm×30mm×2.2mm) with deionized water and ethanol by ultrasonic cleaning and then place it in an oven to dry. After drying, place it in a surface plasma cleaner and clean it under the conditions of working power of 60W, working pressure of 100kPa and working time of 2min; spin-coat the prepared dispersion onto the surface of FTO glass in three steps. The first step is spin-coating at 800r / s for 30s, the second step is spin-coating at 1600r / s for 30s, and the third step is spin-coating at 2000r / s for 30s. Then anneal at 350℃ for 30min to obtain Bi2WO6 electrochromic film.
[0052] Comparative Example 2:
[0053] (1) Preparation of Bi2WO6 nanopowder;
[0054] 1.98 g of sodium tungstate dihydrate and 2.91 g of bismuth nitrate pentahydrate were mixed and dissolved in 200 mL of deionized water. The mixture was placed in an ultrasonic bath for 30 min to complete the precipitate reaction. The supernatant was removed, and the precipitate was washed three times with deionized water. The washing solution was then added to a 50 mL high-pressure reactor lined with polytetrafluoroethylene for hydrothermal reaction. The hydrothermal reaction conditions were 180 °C for 20 h. The reaction product was washed and dried by centrifugation with deionized water and ethanol to obtain Bi2WO6 nanoparticles.
[0055] (2) The prepared Bi2WO6 nanoparticles were modified with hydrogen ions;
[0056] 872.5 mg of Bi2WO6 nanoparticles prepared in step (1) were weighed and dissolved in 50 mL of 6 mol / L HCl solution. The mixture was heated and stirred at 120 °C for 72 h at a speed of 900 rpm to modify the Bi2WO6 nanoparticles with hydrogen ions. After stirring, deionized water and ethanol were added and centrifuged to wash the precipitate, which was then dried in a 60 °C oven for 12 h to obtain the hydrogen-modified Bi2WO6 nanoparticles. i2 WO6 nanoparticles;
[0057] (3) 0.375g of hydrogen ion-modified B i2 WO6 nanoparticles were dispersed in 5 mL of isopropanol and sonicated for 60 min to obtain a dispersion. FTO conductive glass (30 mm × 30 mm × 2.2 mm) was ultrasonically cleaned with deionized water and ethanol, then dried in an oven. After drying, it was placed in a surface plasma cleaner and cleaned under the following conditions: working power 60 W, working pressure 100 kPa, and working time 2 min. The prepared dispersion was then continuously spin-coated onto the FTO glass surface in three steps: first, at 800 r / s for 30 s; second, at 1600 r / s for 30 s; and third, at 2000 r / s for 30 s. Finally, the film was annealed at 350 °C for 30 min to prepare a hydrogen ion-modified Bi2WO6 electrochromic film.
[0058] Sample analysis:
[0059] Figure 2The images show the XRD patterns of Comparative Example 1, Comparative Example 2, Example 1, and Example 2 products of this invention. Comparative Example 1 shows only Bi₂WO₆ with a layered bismuth structure; no other phase peaks were observed, and the presence of numerous sharp peaks indicates that the hydrothermally synthesized Bi₂WO₆ has high crystallinity. Comparative Example 2 shows lower peak intensities, possibly due to hydrogen ion modification disrupting the original Bi₂WO₆ crystal structure, resulting in poorer crystallinity. In Examples 1 and 2, most peaks correspond well to hydrated tungsten oxide, with only a few peaks corresponding to Bi₂WO₆, indicating that the dual-ion modification replaced most of the bismuth element, yielding a tungsten oxide hydrate with a layered structure.
[0060] Figure 3 These are SEM images of the products from Comparative Example 1, Comparative Example 2, Example 1, and Example 2 of the present invention. Figure 3 (A) in the image is a SEM image of Bi2WO6 nanoparticles prepared in Comparative Example 1. Figure 3 (B) in the image is a SEM image of the hydrogen ion modified Bi2WO6 nanoparticles prepared in Comparative Example 2. Figure 3 (C) is a SEM image of the hydrogen ion and aluminum ion modified Bi2WO6 nanopowder prepared in Example 1; Figure 3 Image (D) in Example 2 shows the SEM image of the hydrogen and zinc ion modified Bi₂WO₆ nanoparticles. It can be seen that the hydrothermally prepared Bi₂WO₆ has a lamellar structure with tightly packed sheets and gaps between layers. After hydrogen ion modification, the larger nanosheets are broken down into smaller lamellar structures, although the layers are still quite thick. After modification with hydrogen and alkali metal ions, the size of the lamellar structure is further reduced, and the thickness of the layers decreases. The gaps between the lamellar structures increase significantly, which is more conducive to ion intercalation and deintercalation reactions.
[0061] Figure 4 These are HRTEM images of the products from Comparative Example 1 and Example 1 of the present invention. Figure 4 (A) in the image is an HRTEM image of Bi2WO6 nanoparticles prepared in Comparative Example 1; Figure 4 Image (B) is an HRTEM image of the hydrogen and aluminum ion modified Bi2WO6 nanoparticles prepared in Example 1. It can be seen that the hydrothermally prepared Bi2WO6 is a lamellar structure grown along the (113) crystal plane with a crystal plane spacing of 0.318 nm. After modification of the Bi2WO6 lattice structure with hydrogen and aluminum ions, the crystal plane spacing is 0.359 nm, and a lamellar structure grown along the (111) crystal plane is obtained. This indicates that the Bi2WO6 lattice structure has changed after the double ion replacement reaction, the crystal plane spacing has become larger, the crystal structure has become more porous, and a large number of reaction sites have been provided.
[0062] Figure 5 This is a graph showing the transmittance variation of the product of Comparative Example 1 under different voltages. The unmodified Bi₂WO₆ electrochromic film exhibits almost no modulation effect in the visible light band, while its transmittance changes very little when a negative voltage is applied in the near-infrared band.
[0063] Figure 6 This is a graph showing the transmittance variation of the product in Comparative Example 2 under different voltages. The hydrogen-modified Bi2WO6 electrochromic film exhibits a weak modulation effect in the visible light band, but the modulation effect is significantly increased in the near-infrared band. Comparative Example 2 shows a modulation amplitude of 35% at 1600 nm.
[0064] Figure 7 , Figure 8 The graphs show the transmittance variation of the products from Examples 1 and 2 of this invention under different voltages. The Bi₂WO₆ electrochromic film modified with dual ions exhibits a significantly increased modulation effect in the visible light band compared to the film modified with only hydrogen ions, and a significantly increased modulation effect in the near-infrared band. The modulation amplitudes at 1600 nm for Examples 1 and 2 are 53% and 55%, respectively.
[0065] Figure 9 The cyclic voltammograms (CVs) of Comparative Example 1, Comparative Example 2, Example 1, and Example 2 are shown. The CV curves illustrate the oxidation and bleaching processes in the electrochromic reaction. The CV curves of the electrochromic films obtained by dual-ion modification in Example 1 and Example 2 have similar shapes. The area of the CV scan in Comparative Example 1 is almost zero, indicating that the unmodified Bi2WO6 electrochromic film has almost no electrochromic properties. The area of the CV scan in Comparative Example 2, which is modified only with hydrogen ions, is smaller than that in Examples 1 and 2, indicating that the electrochemical performance of the film is improved by the dual-ion substitution reaction. The electrochromic film has a higher charge exchange density, and the insertion / deintercalation reaction of ions in the electrochromic film is more likely to occur at a given voltage.
[0066] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.
Claims
1. A preparation method of a dual-ion modified Bi2WO6 electrochromic thin film material, characterized in that, Includes the following steps: (1) Bi2WO6 was prepared by a one-step hydrothermal method. After the reaction was completed, deionized water and ethanol were added respectively, centrifuged, washed and dried to obtain Bi2WO6 nanopowder. (2) The Bi2WO6 nanopowder prepared in step (1) is mixed with nitrate and hydrochloric acid solution. The molar ratio of Bi2WO6 nanopowder to nitrate is 1:1 to 1:
4. The mixture is stirred at 60 to 120°C for 24 to 96 hours. After the reaction is completed, deionized water and ethanol are added and the mixture is centrifuged and washed. The washing liquid is removed and the powder sample is dried to obtain the powder sample, which is the biion-modified Bi2WO6 nanopowder. The nitrate is one or more of aluminum nitrate, zinc nitrate, copper nitrate, nickel nitrate, iron nitrate, manganese nitrate, lithium nitrate, sodium nitrate, and potassium nitrate. (3) The nanoparticles of Bi2WO6 modified by dual ions prepared in step (2) are dispersed in isopropanol and ultrasonically dispersed to obtain a dispersion. The dispersion is then spin-coated onto the surface of a conductive substrate and annealed at 350°C to obtain an electrochromic film.
2. The method for preparing the dual-ion modified Bi2WO6 electrochromic thin film material according to claim 1, characterized in that, In step (1), the hydrothermal reaction conditions are 140~200℃ for 12~24h.
3. The method of claim 1, wherein the method is characterized by: In step (2), the concentration of the hydrochloric acid solution is 6~12 mol / L.
4. The method for preparing the dual-ion modified Bi₂WO₆ electrochromic thin film material according to claim 1, characterized in that, In step (2), the hydrochloric acid solution is replaced with a nitric acid solution, and the concentration of the nitric acid solution is 8~16 mol / L.
5. The method for preparing the dual-ion modified Bi₂WO₆ electrochromic thin film material according to claim 1, characterized in that, In step (2), the pH of the washing solution is less than 7.
6. The method for preparing the dual-ion modified Bi₂WO₆ electrochromic thin film material according to claim 1, characterized in that, In step (3), the ratio of isopropanol to biionic modified Bi2WO6 nanoparticles is 5 mL: 0.25~0.5 g.
7. The method for preparing the dual-ion modified Bi₂WO₆ electrochromic thin film material according to claim 1, characterized in that, In step (3), the conductive substrate is a transparent conductive substrate material.
8. The method for preparing the dual-ion modified Bi₂WO₆ electrochromic thin film material according to claim 1, characterized in that, In step (3), the method of preparing the film is replaced by spraying, scraping or inkjet printing.
9. A method for preparing a bi-ion modified Bi2WO6 electrochromic thin film material according to any one of claims 1-8.