Preparation method and application of niobium tungsten oxide electrochromic film
The electrochromic film of niobium tungsten oxide is directly grown on the conductive glass by solvent-thermal method, which solves the problems of complex and high cost in the existing preparation process, and achieves efficient optical modulation effect and good cycle stability.
Patent Information
- Application Number
- CN202510098051.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-22
- Publication Date
- 2025-04-15
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
The preparation process of existing niobium tungsten oxide electrochromic films is complex, has high consumption costs, and has insufficient optical modulation capability in the entire solar spectrum.
The electrochromic film of niobium tungsten oxide was prepared by solvothermal method. The preparation process was simplified by mixing anhydrous ethanol, deionized water, oxalic acid, niobium source and tungsten source, stirring at room temperature, and then solvothermal reaction was carried out. The film was directly grown on the conductive glass, simplifying the preparation process.
The preparation process is simplified and the cost is reduced. The film has a light modulation amplitude of up to 97.93% in the wavelength range of 300-900nm, and it has good cycling stability without further annealing.
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Figure CN119822648A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of functional thin film materials, and in particular to a preparation method of a niobium tungsten oxide electrochromic thin film and application thereof. Background Art
[0002] Electrochromism is a phenomenon in which the optical properties of a material (reflectivity, transmittance, absorptivity, etc.) undergo stable and reversible color changes under the action of an external electric field, which manifests itself in reversible changes in color and transparency. Materials with electrochromic properties are called electrochromic materials, and devices made of electrochromic materials are called electrochromic devices. Electrochromic materials have attracted much attention because they can achieve photothermal modulation and reduce energy consumption. Niobium tungsten oxide bimetallic materials perform well in electrochromic materials due to the synergistic effect of niobium and tungsten active sites. Niobium tungsten oxide films have a good modulation range, higher coloring efficiency, fast switching response and good cycle stability, and have broad application potential.
[0003] In recent years, the methods of synthesizing niobium tungsten oxide thin films by solution such as hydrothermal method and solvothermal method have attracted wide attention due to their advantages such as low energy consumption, simple preparation equipment and no need for special environment. Sun et al. prepared tungsten niobium bimetallic oxide films with nanowire cluster structure by solvothermal method using ammonium metatungstate and ammonium niobium oxalate as raw materials, reaching a maximum light modulation amplitude of more than 80%, but the cyclic stability was not demonstrated (Advanced Materials Interfaces, 2022, 9, 2101355). Liu et al. prepared niobium tungsten oxide thin films by spin coating using ammonium metatungstate and niobium oxalate as raw materials (ACS Nano, 2022, 16(2): 2621-2628). Cai et al. used electrospray aerosol deposition pyrolysis method to form films (Advanced Energy Materials, 2021, 12(5): 2103106). Liu et al. used spin coating to prepare thin films, but still needed annealing treatment (ACS Nano, 2022, 16(2): 2621-2628). The process of preparing these films is relatively complicated, the cost is high, and the atomic utilization rate is low. Therefore, the current research focus is to use mild solvent thermal to simply prepare niobium tungsten oxide films with a large modulation range, while further improving the optical modulation ability of niobium tungsten oxide films in the entire solar spectrum, so as to expand the market for the practical application of electrochromic glass. Summary of the invention
[0004] In view of the deficiencies in the prior art, the present invention provides a method for preparing a niobium tungsten oxide electrochromic film and its application, which solves the problem that the preparation process of the traditional film is relatively complicated and the consumption cost is high.
[0005] To achieve the above objectives, the present invention is implemented by the following technical scheme: A method for preparing a niobium tungsten oxide electrochromic film, comprising the following steps:
[0006] S1. Preparation of precursor solution
[0007] Firstly, anhydrous ethanol and deionized water are mixed in a beaker to prepare a mixed solution, then dihydrated oxalic acid is added to the mixed solution, and then a niobium source and a tungsten source are added to the mixed solution, and the mixture is stirred at room temperature to obtain a precursor solution;
[0008] S2. Preparation of color-changing films
[0009] The conductive glass is inserted into the precursor solution to carry out a solvothermal reaction. After the reaction is completed, the solution is cooled to room temperature. The conductive glass is washed and dried to obtain an electrochromic film.
[0010] Preferably, in step S1, the niobium source is niobium pentachloride, the tungsten source is ammonium metatungstate, and the atomic ratio of niobium element to tungsten element in the niobium source and the tungsten source is (1-10): (10-1).
[0011] Preferably, in step S2, the conductive glass is indium tin coated glass or fluorine-doped tin oxide glass.
[0012] Preferably, in the step S2, the temperature of the solvent thermal reaction is 120-190° C. and the time is 4-10 h.
[0013] Preferably, in the step S2, the film does not need further annealing treatment and can be used directly after drying.
[0014] The present invention also provides a niobium tungsten oxide electrochromic film prepared by the above preparation method. The niobium tungsten oxide film obtained by the above preparation method is directly grown on conductive glass. The obtained niobium tungsten oxide film has strong adhesion to the conductive glass and exhibits excellent electrochromic performance and cycle stability. The optimal light modulation amplitude of the film in the wavelength range of 300-900nm is as high as 97.93%.
[0015] The present invention provides a method for preparing a niobium tungsten oxide electrochromic film and its application, which has the following beneficial effects:
[0016] 1. The present invention provides a method for thermally preparing a niobium tungsten oxide electrochromic film with a solvent having a simple preparation process and a mild reaction, which has no complex requirements on preparation conditions and is conducive to commercial production.
[0017] 2. The niobium tungsten oxide film of the present invention does not require the preparation of a seed layer. The niobium tungsten oxide film layer grows in close contact with the conductive glass, which is beneficial to electron transmission, thereby achieving a fast electrochromic response speed and excellent cycle efficiency, and is suitable for use in electrochromic devices and related fields.
[0018] 3. The niobium tungsten oxide film prepared by the present invention has a wider optical modulation range and a higher light modulation amplitude than common electrochromic materials, and can block solar radiation in the colored state, thus meeting the demand for electrochromic materials in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is a schematic structural diagram of the electrochromic device of the present invention;
[0020] Figure 2 The XRD spectra of the niobium tungsten oxide electrochromic film and FTO glass prepared in Example 1;
[0021] Figure 3 The CV curve of the niobium tungsten oxide electrochromic film prepared in Example 1 from -2V to 1V;
[0022] Figure 4 The transmittance curves of the niobium tungsten oxide electrochromic film prepared in Example 1 in the colored and faded states respectively;
[0023] Figure 5 The solar radiation transmittance curves of the niobium tungsten oxide electrochromic film prepared in Example 1 in the colored and faded states respectively;
[0024] Figure 6 This is a diagram of the coloring efficiency of the niobium tungsten oxide electrochromic film prepared in Example 1;
[0025] Figure 7 This is a kinetic curve diagram of the niobium tungsten oxide electrochromic film prepared in Example 1;
[0026] Figure 8 This is a SEM image of the niobium tungsten oxide electrochromic film prepared in Example 1;
[0027] Fig. 9 This is a SEM image of the niobium tungsten oxide electrochromic film prepared in Example 2;
[0028] Fig.10 This is a SEM image of the niobium tungsten oxide electrochromic film prepared in Example 3;
[0029] Fig.11 This is a SEM image of the niobium tungsten oxide electrochromic film prepared in Example 4. DETAILED DESCRIPTION
[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0031] Embodiment 1:
[0032] The embodiment of the present invention provides a method for preparing a niobium tungsten oxide electrochromic film, comprising the following steps:
[0033] S1. Preparation of precursor solution
[0034] 14 mL of anhydrous ethanol and 21 mL of deionized water were mixed in a beaker at room temperature to prepare a mixed solution, and then 5.0135 g of oxalic acid dihydrate was added to the mixed solution, and then 0.0535 g of niobium pentachloride and 0.1002 g of ammonium metatungstate were added to the mixed solution, and the mixture was stirred at room temperature for 45 minutes to obtain a precursor solution;
[0035] S2. Preparation of color-changing films
[0036] The precursor solution is transferred to the inner lining of a polytetrafluoroethylene high-pressure hydrothermal autoclave, and then the fluorine-doped tin oxide glass is inserted into the precursor solution. The inner lining of the hydrothermal autoclave is placed in the steel shell of the high-pressure hydrothermal autoclave, and the autoclave is placed in an oven and kept at 180°C for 4 hours for a solvent thermal reaction. After the reaction is completed, it is cooled to room temperature, the conductive glass is taken out, washed with water and ethanol in turn, and dried at room temperature to obtain a niobium tungsten oxide electrochromic film.
[0037] Figure 2 The GIXRD spectrum of the niobium tungsten oxide film of Example 1. In addition to the diffraction peak of FTO conductive glass, the positions and relative intensities of the two diffraction peaks marked in curve a of Example 1 are consistent with the JPCDS card (75-0561), indicating that the material of the film is Nb 18 W 16 O 93 ;from Figure 3 This is the CV curve of the niobium tungsten oxide film from -2 to 1V in Example 1. Figure 4 The color-fading curve of the film of Example 1 at 300-900nm shows that the light modulation range reaches a maximum value of 97.93% at 888nm; Figure 5 The solar radiation transmittance curve corresponding to the wavelength range of 300-900nm of Example 1; Figure 6 is a coloring efficiency diagram of Example 1; Figure 7 The kinetic curve of Example 1 at 888 nm; Figure 8 This is a SEM image of the surface of the niobium tungsten oxide film prepared in Example 1.
[0038] Embodiment 2:
[0039] The present embodiment prepares a niobium tungsten oxide film according to the method of Example 1, except that the atomic ratio of niobium to tungsten in the precursor solution is 1:4, the amount of niobium pentachloride weighed is 0.0535 g, and the amount of ammonium metatungstate weighed is 0.1981 g.
[0040] Fig. 9 This is a SEM image of the surface of the niobium tungsten oxide film prepared in Example 2.
[0041] Embodiment three:
[0042] The present embodiment prepares a niobium tungsten oxide film according to the method of Example 1, except that the atomic ratio of niobium to tungsten in the precursor solution is 1:10, the amount of niobium pentachloride weighed is 0.0538 g, and the amount of ammonium metatungstate weighed is 0.5025 g.
[0043] Fig.10 This is a SEM image of the surface of the niobium tungsten oxide film prepared in Example 3.
[0044] Embodiment 4:
[0045] The present embodiment prepares a niobium tungsten oxide film according to the method of the first embodiment, except that the atomic ratio of niobium to tungsten in the precursor solution is 10:1, the amount of niobium pentachloride weighed is 0.5350 g, and the amount of ammonium metatungstate weighed is 0.1012 g.
[0046] Fig.11 This is a SEM image of the surface of the niobium tungsten oxide film prepared in Example 4.
[0047] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A method for preparing a niobium tungsten oxide electrochromic film, characterized in that: The following steps are involved: S1. Preparation of precursor solution Firstly, anhydrous ethanol and deionized water are mixed in a beaker to prepare a mixed solution, then dihydrated oxalic acid is added to the mixed solution, and then a niobium source and a tungsten source are added to the mixed solution, and the mixture is stirred at room temperature to obtain a precursor solution; S2. Preparation of color-changing films The conductive glass is inserted into the precursor solution to carry out a solvothermal reaction. After the reaction is completed, the solution is cooled to room temperature. The conductive glass is washed and dried to obtain an electrochromic film.
2. The method for preparing a niobium tungsten oxide electrochromic film according to claim 1, characterized in that: In the step S1, the niobium source is niobium pentachloride, and the tungsten source is ammonium metatungstate. The atomic ratio of niobium element to tungsten element in the niobium source and the tungsten source is (1-10): (10-1).
3. The method for preparing a niobium tungsten oxide electrochromic film and its application according to claim 1, characterized in that: In the step S2, the conductive glass is indium tin coated glass (ITO) or fluorine doped tin oxide glass (FTO).
4. The method for preparing a niobium tungsten oxide electrochromic film and its application according to claim 1, characterized in that: In the step S2, the temperature of the solvent thermal reaction is 120-190° C. and the time is 4-10 h.
5. The niobium tungsten oxide electrochromic film prepared according to the method for preparing a niobium tungsten oxide electrochromic film according to any one of claims 1 to 5.
6. Use of the niobium tungsten oxide electrochromic film according to claim 5 in the preparation of electrochromic devices.