Flaky tungsten bronze powder and application thereof

Abstract

The invention belongs to the technical field of thermal insulation coatings and photocatalytic degradation agents, and particularly relates to flaky cesium tungsten bronze powder and application thereof. The cesium tungsten bronze nanosheet is prepared by using a hydrothermal method and innovatively adopting alkyl sulfate and / or sulfonate and / or alkyl sulfonate and / or sulfate and / or disulfate as a morphology control agent. According to the method, a proper amount of stabilizer with a proper concentration is introduced, tungstate ions are compelled to be chelated with dissociated carboxyl, a relatively stable tungstate complex is formed in an acid solution, and the yield of the nano-sheet cesium-tungsten bronze can be increased as much as possible by matching with a shape control agent with a proper type and a proper concentration. The preparation process is simple and controllable, and the obtained product can be used for preparing a water-based transparent heat-insulating coating or film or used as a photocatalytic degradation agent. The infrared light shielding rate of the prepared film is greater than 95%. When the product is directly used as a photocatalytic degradation agent, the photocatalytic degradation efficiency and performance of the product are extremely excellent.

Description

Technical Field

[0001] The present invention belongs to the technical field of heat-insulating coatings, and particularly relates to a flaky cesium tungsten bronze powder and its application. Background Art

[0002] Under the background of the development of urbanization in China and "dual carbon", tungsten bronze stands out among many heat-shielding functional materials due to its broad-band near-infrared absorption (780 - 2500 nm), high visible light transmittance, good durability and temperature stability, and low solar heat coefficient. It has excellent application prospects in realizing controllable modulation of sunlight and reducing building power consumption.

[0003] Compared with cesium tungsten bronze of other morphologies, flaky nano-cesium tungsten bronze has a richer energy band structure, so it has higher infrared and ultraviolet absorption properties, and has more important significance and promotion value in practical applications. Although in recent years, cesium tungsten bronze nano-materials with different morphologies, such as nano-rods, nano-particles and nano-fibers, have been successfully synthesized, so far, there is still a lack of reports on effective preparation methods for controllable synthesis of cesium tungsten bronze nano-sheets. On the one hand, due to the incorporation of Cs + the octahedral framework structure of WO 6 is severely distorted; on the other hand, in the crystal structure of tungsten bronze, (002) is a close-packed plane with a high surface energy, so cesium tungsten bronze will grow along the c-axis

[002] direction, and finally rod-shaped crystals are obtained, which all lead to difficulty in controlling the synthesis of flaky tungsten bronze crystals. Liu, G. H. et al. (Materials and Design, 194(2020) 108955) used ammonium paratungstate as the tungsten source and thiourea as the morphology control agent to synthesize nano-particles containing cesium tungsten bronze nano-sheets, but most of the obtained nano-particles are still nano-rods, and the nano-sheets only account for a part. In addition, ammonium paratungstate, thiourea, oleylamine, etc. used in this method are relatively expensive. Moreover, due to the use of thiourea, the reaction process is accompanied by the generation of H 2 S, which is not environmentally friendly. Patent CN106892460B discloses a synthesis method of cesium tungsten bronze. First, a precursor is obtained by high-energy ball milling mechanical chemical reaction method, and then it is mixed with an alkali metal source substance and heat-treated in a reducing atmosphere to obtain cesium tungsten bronze nano-particles, but its flaky morphology is not typical, and it has the disadvantages of high energy consumption and high requirements for instrument equipment. Patent CN115231617B discloses a method for obtaining cesium tungsten bronze nano-sheets by using WO 3 nano-sheets as the tungsten source and adopting a solid-phase method, but it also has the disadvantages of poor retention effect of the WO 3 flaky morphology and unclear flaky morphology of cesium tungsten bronze nano-particles.

[0004] The current preparation methods either cannot well control the morphology of cesium tungsten bronze to obtain nanosheets, or the effects are not satisfactory, the costs are high, and they are not environmentally friendly. Therefore, it is still a challenge to find a method with significant effects and low costs to control the morphology of nanoscale cesium tungsten bronze. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to solve the disadvantages of the existing cesium tungsten bronze nanosheet morphology control solutions, such as few solutions, unsatisfactory effects, high costs, and unfriendly environment, and provides a method with significant effects and low costs for controllably preparing flaky cesium tungsten bronze nanometer powder. This method can also be extended to the preparation of other alkali tungsten bronze nanosheets.

[0006] A kind of flaky cesium tungsten bronze powder is prepared by the following steps:

[0007] Step 1,

[0008] According to the molar ratio of cesium to tungsten (n(Cs) / n(W)) of 0.2 - 0.4, a soluble tungsten source and a cesium source are prepared. The soluble tungsten source and the cesium source are dissolved in a solvent and stirred evenly to obtain a standby solution A; the pH value of the standby solution is adjusted to 1 - 2, and then a morphology control agent, a stabilizer, and a reducing agent are added and stirred evenly to obtain a standby solution B; the morphology control agent is selected from alkyl sulfates, sulfonates, alkyl sulfonates, sulfates, and bisulfates; the stabilizer is an organic acid; in the standby solution B, the concentration of W element is 0.05 - 0.15 mol / L, preferably 0.06 - 0.1 mol / L, the concentration of the morphology control agent is 0.3 - 4.5 mol / L, preferably 0.56 - 3.36 mol / L, the concentration of the guiding agent is 0.3 - 1.8 mol / L, preferably 0.66 - 1.32 mol / L, and the concentration of the reducing agent is 0.3 - 2.5 mol / L, preferably 0.5 - 1.5 mol / L;

[0009] Step 2,

[0010] The standby solution B is poured into a hydrothermal autoclave for hydrothermal reaction. The hydrothermal temperature is controlled between 200 - 260 °C, and the hydrothermal time is 10 - 24 h. After the hydrothermal reaction is completed, a precipitate is obtained. After solid-liquid separation, the solid is washed and dried to obtain flaky cesium tungsten bronze nanometer powder.

[0011] In Step 1, the molar ratio of cesium to tungsten (n(Cs) / n(W)) is 0.2 - 0.4, and further preferably 0.32 - 0.36.

[0012] For industrial application, a weighing tool including an electronic balance is used to weigh the tungsten source and the cesium source.

[0013] In Step 1, the cesium source is selected from at least one of cesium sulfate, cesium chloride, cesium hydroxide, cesium carbonate, and cesium acetate, preferably cesium sulfate.

[0014] In Step 1, the tungsten source is selected from at least one of sodium tungstate, ammonium metatungstate, and ammonium tungstate, preferably sodium tungstate.

[0015] The solvent includes water, preferably deionized water. For industrial applications, after adding the cesium source and tungsten source to the solvent, stir until completely dissolved. Of course, to improve the dissolution efficiency, warm water or even water at a higher temperature can be used to dissolve the cesium source and tungsten source.

[0016] Adjust the pH of the standby solution A to 1 - 2 with sulfuric acid, preferably 1.5 - 2. In actual applications, during the process of adjusting the pH of the standby solution A to 1 - 2 with sulfuric acid, a pale yellow H 2 WO 4 .

[0017] Preferably, in Step 1, the morphology control agent includes C 12 H 25 SO 4 Na (SDS), Na 2 SO 4 , NaHSO 4 , K 2 SO 4 , KHSO 4 , (NH 4 ) 2 SO 4 , NH 4 HSO 4 or several of them. Further preferably, it is Na 2 SO 4 .

[0018] Preferably, the stabilizer includes one or several of oxalic acid, citric acid, and acetic acid, and further preferably oxalic acid.

[0019] Preferably, the reducing agent includes one or several of L - tartaric acid, oleic acid, and oleylamine. At the same time, after adding the morphology control agent, stabilizer, and reducing agent, the temperature of the solution can also be raised to 50 - 70 °C, preferably 60 - 65 °C. The advantage of such an operation is that it helps the dissolution of the morphology control agent, stabilizer, and reducing agent.

[0020] In the present invention, the concentrations of the respective raw materials in the standby solution B are controlled; because only when the concentrations of the respective raw materials are appropriate can they play a synergistic role, effectively control the growth of cesium tungsten bronze nanosheets, and improve the yield of cesium tungsten bronze nanosheets. If the molar ratio of cesium to tungsten (n(Cs) / n(W)) is too high, CsW 1.6 O 6miscellaneous phases. If the molar ratio of cesium to tungsten (n(Cs) / n(W)) is too low, it will cause Cs + to be unable to be effectively incorporated. If the concentration of the morphology control agent is too high, it will lead to low yield, introduction of impurities, and poor morphology control effect. If it is too low, it will cause ineffective morphology control. If the concentration of the stabilizer is too high, it will cause problems such as reduced yield. If it is too low, it will cause problems such as a decrease in the reaction system. In the present invention, the relationship between the reducing agent and the tungsten source used is: H + ions react with WO 4 2- to generate H 2 WO 4 precursor. Under high temperature and high pressure conditions, the precursor decomposes to generate [WO 6 octahedrons; under the reduction of the reducing agent, the [WO 6 octahedrons gradually grow by bridging. Finally, Cs + is incorporated into the hexagonal channels between the [WO 6 octahedrons to obtain cesium tungsten bronze nanosheets

[0021] Preferably, in step 2, the hydrothermal temperature is 220~230 °C.

[0022] Preferably, in step 2, the hydrothermal time is 12~16 h.

[0023] In actual application, after the hydrothermal reaction is completed, the blue precipitate is washed successively with deionized water and ethanol, and dried in vacuum to obtain blue cesium tungsten bronze nano powder.

[0024] The blue cesium tungsten bronze powder obtained by the present invention includes nano-sheet blue cesium tungsten bronze powder.

[0025] As one of the optimal solutions, for a flaky cesium tungsten bronze powder, the concentration of Na 2 SO 4 in the standby solution B is 2~2.5 mol / L, the concentration of oxalic acid is 0.7~0.85 mol / L, and the concentration of L-tartaric acid is 0.8~1.2 mol / L.

[0026] The application of a flaky cesium tungsten bronze powder of the present invention includes using it as a photocatalytic degradation agent to degrade pollutants, and the pollutants are preferably organic pollutants.

[0027] The flaky cesium tungsten bronze powder developed by the present invention has a strong adsorption and degradation ability for organic pollutants. For example, when the cesium tungsten bronze nanosheets are added to a solution with a rhodamine B concentration of 10 mg / L at a ratio of 1 mg / mL, under darkroom conditions, the adsorption rate of rhodamine B is greater than 80% within 30 min; under the irradiation of a 300W xenon lamp, the degradation rate of rhodamine B is greater than 91% within 120 min. By increasing the dosage of the cesium tungsten bronze nanosheets, the effect can be further improved.

[0028] The application of a flaky cesium tungsten bronze powder of the present invention includes making it into an aqueous transparent heat-insulating coating or film.

[0029] Preferably, for the application of a flaky cesium tungsten bronze powder of the present invention, the cesium tungsten bronze aqueous transparent heat-insulating coating mainly comprises the following components in parts by mass: 50 - 70 parts of aqueous polyurethane, 15 - 30 parts of a dispersion liquid of flaky blue cesium tungsten bronze powder. After mixing evenly, it is stirred at a high speed at a stirring rate of 1000 - 2000 r / min for 45 - 90 min to obtain a uniformly and stably dispersed cesium tungsten bronze aqueous transparent heat-insulating coating.

[0030] In the dispersion liquid of flaky blue cesium tungsten bronze powder, the mass percentage content of the flaky blue cesium tungsten bronze powder is 10% - 30%, and the liquid used is deionized water.

[0031] For the application of a flaky cesium tungsten bronze powder of the present invention, after obtaining the cesium tungsten bronze aqueous transparent heat-insulating coating,

[0032] it is coated on a carrier, and after being fully dried, a blue transparent film is finally obtained. The carrier is selected from one of a glass sheet, an acrylic board, a PET board, a PVC board, and a PC board.

[0033] Preferably, the mass percentage content of the aqueous polyurethane is 30% - 50%.

[0034] Preferably, in the dispersion liquid of flaky blue cesium tungsten bronze powder, the mass percentage content of the flaky blue cesium tungsten bronze powder is 20% - 30%.

[0035] As a further preference, the flaky blue cesium tungsten bronze powder is a nanosheet blue cesium tungsten bronze powder.

[0036] Principle and advantages:

[0037] Benefiting from the quantum confinement in the vertical two-dimensional plane direction, the freely moving carriers in the cesium tungsten bronze nanosheets are confined in a two-dimensional space, forcing them to occupy a restricted area, thereby leading to the tuning of the light response characteristics. In addition, due to its large specific surface area, unsaturated surface coordination, and high aspect ratio, the cesium tungsten bronze nanosheets have distinct physical, chemical, electrical, and optical properties and excellent transparent heat-insulating ability.

[0038] The cesium tungsten bronze nanosheets developed and prepared by the present invention have far better full-spectrum absorption performance than ordinary tungsten bronze, and their photocatalytic degradation performance is far better than that of existing tungsten bronze. At the same time, in the cesium tungsten bronze nanosheets developed and prepared by the present invention, W 5+ acts as x a trap center for photo-generated electrons in Cs 3 WO

[0039] The present invention uses the hydrothermal method and innovatively uses alkyl sulfates and / or sulfonates and / or alkyl sulfonates and / or sulfates and / or bisulfates (preferably sulfates with alkali metals as cations, such as Na 2 SO 4 、K 2 SO 4 etc.) as morphology control agents to prepare cesium tungsten bronze nanosheets. The morphology control agents selected by the present invention can not only promote the formation of the metastable hexagonal phase, but also act as structure-directing agents to assist in the construction of nanosheets by controlling the growth rate of different crystal planes through selective adsorption and desorption, and finally realize the controllable preparation of cesium tungsten bronze nanosheets.

[0040] The present invention introduces an appropriate concentration and amount of stabilizer to force tungstate ions to chelate with dissociated carboxyl groups to form a relatively stable tungstate complex in an acidic solution. Combining with an appropriate type and concentration of morphology control agent can improve the yield of nanosheet-like cesium tungsten bronze as much as possible.

[0041] Beneficial effects

[0042] The present invention prepares cesium tungsten bronze nanosheets by the hydrothermal method. This process has the advantages of simple control and simple technological process. The prepared nano-powders have excellent dispersibility and can be widely used in infrared-blocking energy-saving coatings or films and photocatalytic degradation agents.

[0043] The morphology control agents used in the present invention have the advantages of environmental friendliness, superior morphology control effect, low price, etc., and the tungsten source used is also convenient for high-efficiency and low-cost industrial application. This preparation method is convenient for controlling the product phase, has a simple process, a high product yield, and a low production cost. The prepared nano-powders have the outstanding advantages of high chemical stability and strong near-infrared shielding ability. The cesium tungsten bronze nano-powders synthesized by the present invention can be widely used in the preparation of infrared-blocking and heat-insulating coatings or films.

[0044] The cesium tungsten bronze nanosheets developed and prepared by the present invention have excellent photocatalytic activity and can achieve efficient and rapid degradation of organic substances. The cesium tungsten bronze nanosheets developed and prepared by the present invention can be used to develop glass films with functions of transparent heat insulation, self-cleaning, and environmental protection, which is of great significance for alleviating current building energy consumption and pollutant emissions. Description of the Drawings

[0045] Figure 1 It is the XRD pattern of the cesium tungsten bronze nanosheets in Example 1 of the present invention.

[0046] Figure 2 It is the scanning electron microscope image of the cesium tungsten bronze nanosheets in Example 1 of the present invention.

[0047] Figure 3 It is the UV-Vis-NIR spectrum of the cesium tungsten bronze nanosheets in Example 1 of the present invention.

[0048] Figure 4 It is the adsorption / photocatalysis curve of the cesium tungsten bronze nanosheets in Example 1 of the present invention to Rhodamine B. Figure 5 It is the XRD pattern of the tungsten oxide nanoparticles in Comparative Example 1 of the present invention.

[0049] Figure 6 It is the scanning electron microscope image of the cesium tungsten bronze nanosheets in Comparative Example 2 of the present invention.

[0050] Figure 7 It is the scanning electron microscope image of the cesium tungsten bronze nanosheets in Comparative Example 3 of the present invention.

[0051] Figure 8 It is the scanning electron microscope image of the cesium tungsten bronze nanosheets in Example 2 of the present invention.

[0052] Figure 9 It is the scanning electron microscope image of the cesium tungsten bronze nanosheets in Example 3 of the present invention.

[0053] Figure 10 It is the scanning electron microscope image of the cesium tungsten bronze nanosheets in Example 4 of the present invention.

[0054] Figure 11 It is the scanning electron microscope image of the cesium tungsten bronze nanosheets in Example 5 of the present invention.

[0055] Figure 12 It is the scanning electron microscope image of the cesium tungsten bronze nanosheets in Example 6 of the present invention. Detailed Description of the Invention

[0056] Example 1:

[0057] a. Add 4 mmol of Na 2 WO 4 ·H 2O and 0.66 mmol Cs 2 SO 4 was dissolved in 50 mL of deionized water, and the pH was adjusted to 2.0 with dilute H 2 SO 4 Then, 112 mmol of Na 2 SO 4 (morphology control agent), 39 mmol of oxalic acid (stabilizer), and 50 mmol of L-tartaric acid (reductant) were added to the above solution.

[0058] b. The suspension was transferred to a 100 mL hydrothermal autoclave and heated at 220 °C for 12 h for hydrothermal reaction. After the reaction, the precipitate was collected by centrifugation, washed several times with deionized water and absolute ethanol, and dried overnight in a vacuum drying oven at 70 °C to obtain nano-sheet-like cesium tungsten bronze powder.

[0059] c. 60 parts of aqueous polyurethane (the solid content of aqueous polyurethane is 50 wt%), 30 parts of nano-sheet-like cesium tungsten bronze powder dispersion (in the nano-sheet-like cesium tungsten bronze powder dispersion, the mass percentage content of nano-sheet-like cesium tungsten bronze powder is 30% and the solvent is deionized water) were mixed evenly and stirred at a high speed of 1500 r / min for 60 min to obtain a uniformly and stably dispersed cesium tungsten bronze aqueous transparent heat-insulating coating. Then, an appropriate amount of the slurry was applied on a glass sheet by roll coating method, and after sufficient drying, a blue transparent film was finally obtained. The transmittance curve of the film was tested by a U-4100 ultraviolet-visible near-infrared spectrophotometer.

[0060] d. Using a double-layer beaker, the photocatalytic degradation reaction of rhodamine B was carried out under the irradiation of a xenon lamp with a power of 300 W. The initial concentration of rhodamine B was 10 mg / L, and the initial concentration of cesium tungsten bronze nanosheets was 1 mg / mL. First, the powder was added to the rhodamine B solution and left standing in the dark for 30 min to test its effect on the concentration of rhodamine B; then, it was irradiated with a 300 W xenon lamp to test its degradation effect on rhodamine B under this condition. An ultraviolet-visible spectrophotometer was used to measure the absorbance (Abs) of rhodamine B at a wavelength of 554 nm every 15 min to test the photocatalytic effect of the powder. Figure 1 is the XRD pattern of the nano-sheet-like cesium tungsten bronze powder prepared in Example 1. It can be seen that the cesium tungsten bronze nanosheets prepared in Example 1 are in good agreement with the standard pattern of Cs 0.32 WO 3 (PDF#83-1334), no impurity diffraction peaks were detected, and it has a high crystallinity.

[0061] Figure 2It is the SEM image of the cesium tungsten bronze nanosheets prepared in Example 1. It can be seen that the cesium tungsten bronze nanoparticles prepared in Example 1 are flaky and have relatively uniform particle sizes.

[0062] Figure 3 It is the UV-Vis-NIR spectrum of the cesium tungsten bronze nanosheets prepared in Example 1. From Figure 3 it can be seen that the maximum transmittance of the cesium tungsten bronze thin film in the visible light region is 60%, while the maximum shielding rate in the infrared region is 96.3%. Therefore, this thin film has semi-transparency and relatively excellent near-infrared shielding performance.

[0063] Figure 4 It is the adsorption / photocatalysis curve of rhodamine B by the cesium tungsten bronze nanosheets in Example 1. From Figure 4 it can be seen that the cesium tungsten bronze nanosheets prepared in Example 1 have a strong adsorption capacity for rhodamine B. Under darkroom conditions, the adsorption rate of rhodamine B reached 81.27% within 15 min; after irradiation with a 300 W xenon lamp for 120 min, the adsorption / degradation rate of rhodamine B reached 91.81%. Therefore, this cesium tungsten bronze nanosheet has strong photocatalytic activity and has the potential to develop into a photocatalytic degradation agent to degrade pollutants and achieve photocatalytic performance.

[0064] Comparative Example 1:

[0065] a. Dissolve 4 mmol Na 2 WO 4 ·H 2 O and 0.66 mmol Cs 2 SO 4 in 50 mL of deionized water, and adjust the pH to 0.1 with dilute H 2 SO 4 . Then add 112 mmol Na 2 SO 4 and 39 mmol of oxalic acid as a morphology control agent and stabilizer, and 50 mmol L-tartaric acid as a reducing agent.

[0066] b. Transfer the suspension to a 100 mL hydrothermal autoclave and carry out a hydrothermal reaction at 220 °C for 12 h. After the reaction is completed, centrifuge to collect the precipitate, wash it several times with deionized water and absolute ethanol, and dry it overnight in a 70 °C vacuum drying oven. The XRD pattern of the obtained product is in good agreement with the standard pattern of WO 3 (PDF#75-2187), and no impurity diffraction peaks are detected, as Figure 5 shown. It can be seen from Example 1 and Comparative Example 1 that the pH has a crucial impact on the system developed in the present invention, and it can directly affect whether the product phase is the cesium tungsten bronze phase.

[0067] Comparative Example 2:

[0068] a. Dissolve 4 mmol of Na 2 WO 4 ·H 2 O and 0.66 mmol of Cs 2 SO 4 in 50 mL of deionized water, and adjust the pH to 2.0 with dilute H 2 SO 4 Then add 28 mmol of Na 2 SO 4 and 39 mmol of oxalic acid as a morphology control agent and stabilizer, and 50 mmol L-tartaric acid as a reducing agent.

[0069] b. Transfer the suspension to a 100 mL hydrothermal reactor, heat it at 240 °C for 12 h for hydrothermal reaction. After the reaction, centrifuge to collect the precipitate, wash it several times with deionized water and absolute ethanol, and dry it overnight in a vacuum drying oven at 70 °C. The morphology of the obtained product is nanorods. As Figure 6 shown in Examples 1 and Comparative Example 2, it can be seen that the concentration of the morphology control agent (or the concentration relative to the W and Cs sources) can directly affect whether a flaky product can be obtained. If the concentration is too low, it is difficult to obtain a product with a very high proportion of nanosheets.

[0070] Comparative Example 3:

[0071] a. Dissolve 4 mmol of Na 2 WO 4 ·H 2 O and 0.66 mmol of Cs 2 SO 4 in 50 mL of deionized water, and adjust the pH to 2.0 with dilute H 2 SO 4 Then add 168 mmol of Na 2 SO 4 and 39 mmol of oxalic acid as a morphology control agent and stabilizer, and 50 mmol L-tartaric acid as a reducing agent.

[0072] b. Transfer the suspension to a 100 mL hydrothermal reactor, heat it at 220 °C for 12 h for hydrothermal reaction. After the reaction, centrifuge to collect the precipitate, wash it several times with deionized water and absolute ethanol, and dry it overnight in a vacuum drying oven at 70 °C.

[0073] The morphology of the obtained product is nanoshort rods, as Figure 7As shown. It can be seen from Example 1 and Comparative Example 3 that the concentration of the morphology control agent (or the concentration relative to the W and Cs sources) can directly affect whether a flaky product can be obtained. If the concentration is too high, it is also very difficult to obtain a product with a very high proportion of nanosheets.

[0074] Example 2:

[0075] a. Dissolve 0.33 mmol of ammonium metatungstate and 1.4 mmol of CsOH in 50 mL of deionized water, and adjust the pH to 1.5 with dilute H 2 SO 4 Then add 84 mmol of Na 2 HSO 4 and 40 mmol of acetic acid as a directing agent, and 2 mL of oleylamine as a reducing agent.

[0076] b. Transfer the suspension to a 100 mL hydrothermal reactor, heat it at 220 °C for 12 h for hydrothermal reaction. After the reaction is completed, centrifuge to collect the precipitate, wash it several times with deionized water and absolute ethanol, and dry it overnight in a vacuum drying oven at 70 °C. The morphology of the obtained product is a mixture of irregular nanosheets and nanorods, as Figure 8 shown.

[0077] Example 3:

[0078] a. Dissolve 4 mmol of Na 2 WO 4 ·H 2 O and 0.6 mmol of Cs 2 SO 4 in 50 mL of deionized water, and adjust the pH to 1 with dilute H 2 SO 4 Then add 90 mmol of NaHSO 4 and 30 mmol of oxalic acid as a morphology control agent and a stabilizer, and 50 mmol of L-tartaric acid as a reducing agent.

[0079] b. Transfer the suspension to a 100 mL hydrothermal reactor, heat it at 220 °C for 24 h for hydrothermal reaction. After the reaction is completed, centrifuge to collect the precipitate, wash it several times with deionized water and absolute ethanol, and dry it overnight in a vacuum drying oven at 70 °C. As Figure 9 shown, the prepared cesium tungsten bronze nanoparticles are a mixture of flakes and rods, and the proportion of flaky particles is relatively high.

[0080] Example 4:

[0081] a. Dissolve 4 mmol of Na 2 WO 4 ·H 2O and 0.72 mmol Cs 2 CO 3 was dissolved in 50 mL of deionized water, and the pH was adjusted to 1.5 with dilute H 2 SO 4 Then, 96 mmol of K 2 SO 4 and 50 mmol of citric acid were added as morphology control agent and stabilizer, and 2 mL of oleylamine was added as reducing agent.

[0082] b. The suspension was transferred to a 100 mL hydrothermal autoclave and heated at 220 °C for 12 h for hydrothermal reaction. After the reaction, the precipitate was collected by centrifugation, washed several times with deionized water and absolute ethanol, and dried overnight in a vacuum drying oven at 70 °C. The morphology of the obtained product was a mixture of irregular nanosheets and nanorods, with a relatively high proportion of sheet-like particles, as Figure 10 shown.

[0083] Example 5:

[0084] a. 4 mmol of (NH 4 ) 2 WO 4 and 0.72 mmol of Cs 2 SO 4 were dissolved in 50 mL of deionized water, and the pH was adjusted to 1 with dilute H 2 SO 4 Then, 96 mmol of C 12 H 25 SO 4 Na (SDS) and 50 mmol of oxalic acid were added as morphology control agent and stabilizer, and 1 mL of oleylamine and 1 mL of oleic acid were added as reducing agents.

[0085] b. The suspension was transferred to a 100 mL hydrothermal autoclave and heated at 220 °C for 12 h for hydrothermal reaction. After the reaction, the precipitate was collected by centrifugation, washed several times with deionized water and absolute ethanol, and dried overnight in a vacuum drying oven at 70 °C. The morphology of the obtained product was a mixture of irregular nanosheets and nanorods, with a relatively high proportion of sheet-like particles, as Figure 11 shown.

[0086] Example 6:

[0087] a. 0.33 mmol of ammonium metatungstate and 1.5 mmol of CsCl were dissolved in 50 mL of deionized water, and the pH was adjusted to 1 with dilute H 2 SO 4 Then, 100 mmol of (NH 4 ) 2 SO4 50 mmol of citric acid was used as the morphology control agent and stabilizer, and 1 mL of oleylamine and 1 mL of oleic acid were used as the reducing agents.

[0088] b. The suspension was transferred to a 100 mL hydrothermal autoclave and heated at 220 °C for 12 h for hydrothermal reaction. After the reaction, the precipitate was collected by centrifugation, washed several times with deionized water and absolute ethanol, and dried overnight in a vacuum drying oven at 70 °C. The morphology of the obtained product was a mixture of irregular nanosheets and nanorods, as Figure 12 shown.

Claims

1. A flaky cesium tungsten bronze powder, characterized in that: Prepared by the following steps: Step 1, A soluble tungsten source and a cesium source are prepared according to a molar ratio of cesium to tungsten (n(Cs) / n(W)) of 0.2-0.4, and the soluble tungsten source and the cesium source are dissolved in a solvent and stirred evenly to obtain a reserve solution A; the pH value of the reserve solution is adjusted to 1-2, and then a morphology control agent, a stabilizer and a reducing agent are added, and stirred evenly to obtain a reserve solution B; the morphology control agent is selected from alkyl sulfates, sulfonates, alkyl sulfonates, sulfates, and hydrogen sulfates; the stabilizer is an organic acid; in the reserve solution B, the concentration of the W element is 0.05-0.15 mol / L, preferably 0.06-0.1 mol / L, the concentration of the morphology control agent is 0.3-4.5 mol / L, preferably 0.56-3.36 mol / L, and the concentration of the stabilizer is 0.3-1.8 mol / L, preferably 0.66-1.32 mol / L, the concentration of the reducing agent is 0.3-2.5 mol / L, preferably 0.5-1.5 mol / L; Step 2, Pour the reserve solution B into the hydrothermal kettle for hydrothermal reaction. The hydrothermal temperature is controlled between 200 and 260 °C and the hydrothermal time is 10 to 24 h. After the hydrothermal reaction, a precipitate is obtained. After solid-liquid separation, the solid is washed and dried to obtain flaky cesium tungsten bronze nanopowder.

2. The flaky cesium tungsten bronze powder according to claim 1, characterized in that: In step 1, the molar ratio of cesium to tungsten (n(Cs) / n(W)) is 0.32-0.

36.

3. The flaky cesium tungsten bronze powder according to claim 1, characterized in that: In step 1, the cesium source is selected from at least one of cesium sulfate, cesium chloride, cesium hydroxide, cesium carbonate, and cesium acetate, preferably cesium sulfate; In step 1, the tungsten source is selected from at least one of sodium tungstate, ammonium metatungstate, and ammonium tungstate, preferably sodium tungstate; In step 1, the solvent includes water, preferably deionized water.

4. The flaky cesium tungsten bronze powder according to claim 1, characterized in that: The pH of the reserve solution A is adjusted to 1-2, preferably 1.5-2, with sulfuric acid.

5. The flaky cesium tungsten bronze powder according to claim 1, characterized in that: In step 1, the morphology control agent includes C 12 H 25 One or more of SO4Na, Na2SO4, NaHSO4, K2SO4, KHSO4, (NH4)2SO4, NH4HSO4, the stabilizer includes one or more of oxalic acid, citric acid, acetic acid, and the reducing agent includes one or more of L-tartaric acid, oleic acid, and oleylamine.

6. The flaky cesium tungsten bronze powder according to claim 1, characterized in that: In step 2, the hydrothermal temperature is 220-230 °C; the hydrothermal time is 12-16 h.

7. An application of flaky cesium tungsten bronze powder, characterized in that: Including using it as a photocatalytic degradation agent.

8. An application of flaky cesium tungsten bronze powder, characterized in that: Including making it into water-based transparent heat-insulating coating or film.

9. The use of a flaky cesium tungsten bronze powder according to claim 8, characterized in that: The cesium tungsten bronze water-based transparent thermal insulation coating mainly includes the following components in parts by weight: 50-70 parts of water-based polyurethane and 15-30 parts of flaky blue cesium tungsten bronze powder dispersion. After mixing evenly, stir at a high speed of 1000-2000 r / min for 45-90 min to obtain a uniformly dispersed and stable cesium tungsten bronze water-based transparent thermal insulation coating.

10. The use of a flaky cesium tungsten bronze powder according to claim 8, characterized in that: In the dispersion of the flaky blue cesium tungsten bronze powder, the mass percentage of the flaky blue cesium tungsten bronze powder is 10% to 30%, and the liquid used is deionized water; The mass percentage of waterborne polyurethane is 30%~50%; After obtaining the cesium tungsten bronze water-based transparent thermal insulation coating, It is applied on a carrier and finally a blue transparent film is obtained after sufficient drying.

Images