Preparation and application of a dual-band optical modulation material and its components

Abstract

The present invention relates to the technical field of optical modulation elements, and specifically to the preparation and application of a dual-band optical modulation material and its elements. The specific technical scheme is: a method for preparing a dual-band optical modulation material, mixing and grinding tungsten oxide, molybdenum oxide and sodium tungstate hydrate, annealing at high temperature in an ammonia atmosphere to obtain Mo-doped two-dimensional tungsten nitride, removing tungsten salt, and oxidizing with nitric acid to obtain Mo and N co-doped tungsten oxide. The present invention successfully prepared Mo and N co-doped WO3·xH2O by in-situ oxidation of metal nitrides. An optical modulation element was assembled by using it as an electrochromic layer and FTO as an ion storage layer. Compared with traditional electrochromic elements, independent regulation of visible light and near-infrared light is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical modulation elements, and in particular to the preparation and application of a dual-band optical modulation material and elements thereof. Background Art

[0002] Compared with traditional color-changing elements, electrochromic elements can adjust external sunlight according to people's wishes, and are widely used because of their large optical modulation range, fast response speed and good reversibility. However, traditional electrochromic materials can only adjust visible light and near-infrared light separately, and cannot balance external light and heat. Although some people have achieved the adjustment of visible light and near-infrared light through the combination of materials, such as W 18 O 49 / PB、W 18 O 49 / P8W 48 , WO 3-x / NbO x and WO 3−x / TiO2, but the composite material preparation process is complicated and the two materials require independent regulation voltage, making it difficult to implement. Therefore, the independent regulation of visible light and near-infrared light based on single-component electrochromic materials has great development prospects, but there are great challenges. Summary of the invention

[0003] In view of the shortcomings of the prior art, the present invention provides a dual-band optical modulation material and the preparation and application of its components. By applying the anion-cation co-doping strategy to WO3 material, Mo and N co-doped WO3·xH2O (x=1, 2) was successfully prepared by in-situ oxidation of metal nitrides. By using it as an electrochromic layer and FTO as an ion storage layer, an optical modulation component was assembled. Compared with traditional electrochromic components, independent regulation of visible light and near-infrared light is achieved.

[0004] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0005] The invention discloses a preparation method of a dual-band optical modulation material. Tungsten oxide, molybdenum oxide and hydrated sodium tungstate are mixed and ground, and high-temperature annealing is performed in an ammonia atmosphere to obtain Mo-doped two-dimensional tungsten nitride. After removing the tungsten salt, the material is oxidized by nitric acid to obtain Mo and N co-doped tungsten oxide.

[0006] Preferably, the concentration of the nitric acid is 0.5-2M.

[0007] Preferably, the molar ratio of the tungsten oxide to the hydrated sodium tungstate is 1-3:1-3, and the doping amount of the molybdenum oxide is a molar ratio of Mo:W of 1:15-20.

[0008] Preferably, the high temperature annealing temperature is 600-800° C., the heating rate is 5-10° C. / min, and the holding time is 2 h.

[0009] Preferably, the flow rate of ammonia gas is 100-200 sccm.

[0010] Preferably, during the oxidation of tungsten nitride with nitric acid, heating is performed at 50° C. for 12 to 48 hours, and after the oxidation is completed, drying is performed at 40° C. for 24 hours.

[0011] Correspondingly, a dual-band optical modulation material prepared by the above preparation method is used to prepare optical elements, and the preparation process is: Mo and N co-doped tungsten oxide is sprayed on FTO as an electrochromic layer, and pure FTO is used as a conductive layer; the FTO conductive layer is used as an ion storage layer, and 1M sulfuric acid is used as an electrolyte layer.

[0012] Correspondingly, an application of the above optical element in a smart window.

[0013] The present invention has the following beneficial effects:

[0014] 1. The dual-band optical modulation material prepared by the present invention can be used as an electrochromic layer in an optical modulation element, and the independent regulation of visible light and near-infrared light can be achieved through color changes under different voltage conditions. The use of this element in the field of smart windows also has excellent heat insulation effects, which is expected to reduce indoor air conditioning energy consumption.

[0015] 2. The preparation of Mo-doped tungsten nitride by the molten salt method is simple to operate and can realize the batch preparation of tungsten nitride. On the other hand, the selection of tungsten salt will not introduce unnecessary impurities, so no special impurity removal treatment is required after the nitridation. At the same time, the in-situ oxidation method of nitric acid not only retains the two-dimensional morphology of tungsten nitride, but also can achieve controllable regulation of the amount of crystal water by adjusting the concentration of nitric acid. The presence of crystal water provides a unique expansion space for ion doping and ensures the cyclic stability of the component. Compared with traditional WO3·H2O components, Mo and N co-doping realizes independent regulation of visible light and near-infrared light, which is conducive to more effective management of external light and heat.

[0016] 3. The present invention provides a method for in-situ oxidation of nitrides to prepare Mo and N co-doped tungsten oxide, which is used as an electrochromic layer to achieve dual-band electrochromic control. Batch preparation of tungsten nitride can be achieved through a simple molten salt method; the in-situ oxidation method of nitric acid can better retain the two-dimensional morphology of the nitride and adjust the concentration of nitric acid to achieve controllable regulation of the amount of crystal water; the use of the component in smart windows can not only effectively manage light and heat, but also have excellent thermal insulation effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The X-ray diffraction pattern and scanning electron microscope image of the product prepared in Example 1 at a 0.5M nitric acid concentration;

[0018] Figure 2 The X-ray diffraction pattern and scanning electron microscope image of the product prepared in Example 1 at a nitric acid concentration of 1 M;

[0019] Figure 3 The X-ray diffraction pattern and scanning electron microscope image of the product prepared in Example 1 at a 2M nitric acid concentration;

[0020] Figure 4 The optical transmission spectra of tungsten oxide with different crystal phases prepared in Example 1 under different voltage conditions;

[0021] Figure 5 The color change pictures of the element prepared in Example 2 under different voltage conditions;

[0022] Figure 6 This is a diagram showing the thermal insulation performance test of the element prepared in Example 3 after being used in a smart window;

[0023] Figure 7 This is the transmission spectrum of tungsten oxide with one crystal water prepared in Comparative Example 1. DETAILED DESCRIPTION

[0024] 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.

[0025] Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0026] The present invention discloses a preparation method of a dual-band optical modulation material, wherein tungsten oxide, molybdenum oxide and hydrated sodium tungstate are mixed and ground, and the mixture is placed in a porcelain boat, and high-temperature nitridation is performed in a muffle furnace under an ammonia atmosphere to obtain Mo-doped two-dimensional tungsten nitride, and excess tungsten salts are removed by washing and centrifugation, and then oxidized by nitric acid of different concentrations, and washed, centrifuged and dried to obtain Mo and N co-doped tungsten oxide (WO3·xH2O) with different crystal water. The concentration of the nitric acid is 0.5-2M. In-situ oxidation with nitric acid can retain the Mo-doped WN 1.5Changing the concentration of nitric acid can achieve controllable regulation of the amount of crystalline water, which can provide unique expansion space for ion doping and reduce the impact of lattice distortion on the cyclic stability of the component.

[0027] Furthermore, the molar ratio of the tungsten oxide to the sodium tungstate hydrate is 1-3:1-3, and more preferably 1:1; the molar ratio of the doping amount of the molybdenum oxide is Mo:W (i.e., the molar ratio between Mo atoms and W atoms in tungsten oxide and sodium tungstate hydrate) is 1:15-20. Experimental verification shows that when the ratio of Mo to W is 1:16, the element has the best transmittance and modulation effect.

[0028] Furthermore, the temperature of the high temperature nitriding is 600-800°C, preferably 750°C. When the temperature is too low, tungsten oxide, molybdenum oxide and sodium tungstate hydrate react to form Mo-doped NaWO3. When the temperature rises to 750°C, NaWO3 is converted into Na2WO4 and Mo-doped WN 1.5 , Na2WO4 can be washed away by washing and centrifugation. When the temperature is too high, N atoms diffuse outward from the W lattice, and Mo-doped WN 1.5 The nanosheets will be transformed into W2N nanoparticles. The heating rate is 5-10°C / min, preferably 5°C / min; the holding time is 2h.

[0029] Furthermore, the flow rate of ammonia gas is 100-200 sccm, preferably 100 sccm.

[0030] Furthermore, after high-temperature nitridation, the product is cooled in the furnace; the nitridation product is washed with water and centrifuged twice, and washed with ethanol and centrifuged once.

[0031] Furthermore, tungsten nitride (Mo-doped WN 1.5 ) During the oxidation with nitric acid, water bath heating is performed under continuous stirring; the water bath heating process is heated at 50°C for 12 to 48 hours, preferably 24 hours. Because when the reaction time is too short, tungsten nitride cannot be completely oxidized. When the reaction time is too long, tungsten oxide is easily dehydrated, and controllable adjustment of different crystal water cannot be achieved. After the oxidation is completed, vacuum drying is performed at 40°C for 24 hours.

[0032] Furthermore, the concentration of nitric acid is 0.5-2M, wherein 0.5M nitric acid can be used to oxidize to obtain Mo and N co-doped WO3·2H2O, 1M nitric acid can be used to oxidize to obtain a mixture of Mo and N co-doped WO3·2H2O and WO3·H2O, and 2M nitric acid can be used to oxidize to obtain Mo and N co-doped WO3·H2O.

[0033] The present invention discloses using the prepared dual-band optical modulation material to prepare an optical element. The preparation process is as follows: using a spraying method to spray Mo and N co-doped tungsten oxide on FTO as an electrochromic layer, and using pure FTO as a conductive layer; using the FTO conductive layer as an ion storage layer, and using 1M sulfuric acid as an electrolyte layer. Mo and N co-doped WO3·xH2O used as an electrochromic layer can realize independent regulation of visible light and near-infrared light by the element. It is applied to smart windows and has a certain heat insulation ability.

[0034] The present invention will be further described below in conjunction with specific embodiments. Example 1

[0035] 2.31g of tungsten oxide, 0.18g of molybdenum oxide and 3.3g of sodium tungstate hydrate were placed in a mortar and ground for 30 minutes. Then 0.4g of the ground mixture was evenly spread in a porcelain boat and placed in a muffle furnace. Under the condition of ammonia, the temperature was raised to 750℃ at a rate of 5℃ / min and kept warm for 2h, and then cooled in the furnace. The ammonia flow rate was 100sccm. After the nitridation was completed, the product was washed with water and centrifuged twice, washed with ethanol and centrifuged once, and finally dried in a vacuum oven at 40℃ for 24h to obtain Mo-doped WN 1.5 Then, three portions of 0.1 g of Mo-doped WN were taken. 1.5 The samples were added into 12 ml of 0.5 M, 1 M and 2 M nitric acid respectively, stirred in a 50 °C water bath for 24 h, then washed with water and centrifuged twice, washed with ethanol and centrifuged once and dried in a vacuum oven at 40 °C for 24 h.

[0036] Figure 1 , 2 3 are the X-ray diffraction patterns and scanning electron microscope images of the products obtained by in-situ oxidation with three concentrations of nitric acid, respectively. From the figures, it can be concluded that tungsten oxide with different crystal water can be obtained by oxidation with different nitric acids, and all of them have a two-dimensional flake morphology.

[0037] Figure 4 The optical transmission spectra of products with different crystalline phases under different voltage conditions show that using Mo and N co-doped WO3·xH2O as the electrochromic layer can achieve independent regulation of visible light and near-infrared light, among which tungsten oxide with one crystal water has the best modulation effect. Example 2

[0038] Mo and N co-doped WO3·xH2O was sprayed on FTO as an electrochromic layer, pure FTO was used as a conductive layer, the FTO conductive layer was used as an ion storage layer, 1M sulfuric acid was used as an electrolyte layer, and 3M double-sided tape was used as a spacer to assemble a 10cm×10cm optical modulation element.

[0039] Figure 5 The electronic photos of the component under different voltages. When a positive voltage (2V) is applied to the component, it allows visible light and near-infrared light to pass through together, which is the bright mode; when a smaller negative voltage (-2V) is applied, the component absorbs near-infrared light and allows visible light to pass through, which is the cold mode; when a larger voltage (-2.8V) is applied, the component absorbs visible light and near-infrared light at the same time, thus achieving the dark mode. Example 3

[0040] Using components with the best modulation effect in the field of smart windows can effectively manage indoor light and heat, and improve people's comfort through controllable adjustment of three modes.

[0041] Figure 6 A thermal insulation performance test was conducted after the component was used in a smart window. The figure shows that the component still has a certain thermal insulation effect after applying different voltages. By reducing heat loss in the room, it is expected to reduce indoor heating energy consumption. Comparative Example 1

[0042] Tungsten oxide with one crystal water was prepared by the following method: 3.3 g Na2WO4·2H2O was dissolved in 50 mL deionized water, 2 M HCl was added and stirred for ten minutes, then 0.64 g H2C2O4 was added to the reaction system, reacted in a water bath at 90°C for 1 hour and centrifuged to obtain.

[0043] Figure 7 : is the transmission spectrum of tungsten oxide with one crystal water. Compared with the transmission spectrum obtained in Example 2, the unmodified tungsten oxide can only achieve the single regulation of near-infrared light.

[0044] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a dual-band optical modulation material, characterized in that: Tungsten oxide, molybdenum oxide and hydrated sodium tungstate are mixed and ground, and annealed at high temperature in an ammonia atmosphere to obtain Mo-doped two-dimensional tungsten nitride. After removing the tungsten salt, Mo and N co-doped tungsten oxide is obtained by oxidation with nitric acid. During the oxidation of tungsten nitride with nitric acid, it is heated at 50°C for 12 to 48 hours; the concentration of the nitric acid is 0.5 to 2M.

2. The preparation method according to claim 1, characterized in that: The molar ratio of the tungsten oxide to the hydrated sodium tungstate is 1-3:1-3, and the doping amount of the molybdenum oxide is a molar ratio of Mo:W of 1:15-20.

3. The preparation method according to claim 1, characterized in that: The high temperature annealing temperature is 600-800° C., the heating rate is 5-10° C. / min, and the heat preservation time is 2 hours.

4. The preparation method according to claim 1, characterized in that: The ammonia flow rate is 100-200 sccm.

5. The preparation method according to claim 1, characterized in that: After oxidation, the mixture was dried at 40 °C for 24 h.

6. An optical element, characterized in that: The preparation process is as follows: Mo and N co-doped tungsten oxide is sprayed on FTO as an electrochromic layer, and pure FTO is used as a conductive layer; the FTO conductive layer is used as an ion storage layer, and 1M sulfuric acid is used as an electrolyte layer; Mo and N co-doped tungsten oxide is prepared by the preparation method described in any one of claims 1 to 5.

7. Use of the optical element according to claim 6 in a smart window.

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