Titanium oxide solid solution material with strong absorption and wide range of regulation LSPR effect and preparation method and application thereof

Abstract

The application discloses a core-shell structure titanium oxide solid solution material with strong absorption and wide range regulation LSPR effect and a preparation method and application thereof. The solid solution material is a core-shell structure with a fluorine-tungsten titanium oxide solid solution as a core and a fluorine-niobium titanium oxide solid solution as a shell. The fluorine-tungsten titanium oxide solid solution in the core is synthesized by an ammonia reaction of a core precursor and a tungsten source. The shell precursor and the niobium source are injected into the fluorine-tungsten titanium oxide solid solution, and after reaction at 280 DEG C-330 DEG C, the synthesis of the fluorine-niobium titanium oxide solid solution shell is realized and the shell is wrapped on the surface of the fluorine-tungsten titanium oxide solid solution core nanoparticles. The application utilizes the influence of the radial distribution of the dopant on the plasma performance, and the fluorine-tungsten titanium oxide solid solution and the fluorine-niobium titanium oxide solid solution with LSPR effect in the near-infrared and the mid-infrared are compounded, so that the solid solution has strong near-infrared absorption and wide range regulation function of the peak position, and has application value in the fields of preparation of transparent heat insulation coating, biological fluorescence imaging and the like.

Description

Technical Field

[0001] This invention relates to a core-shell structured titanium dioxide solid solution, specifically to a core-shell structured titanium dioxide solid solution material with strong absorption in the near-infrared II region and tunable LSPR energy in the near-infrared II region, and its preparation method, belonging to the fields of building energy conservation and fluorescence imaging. Background Technology

[0002] Localized surface plasmon resonance (LSPR) is a phenomenon caused by coherent electron oscillations. Nanoparticles with LSPR properties can produce important optical characteristics such as strong light absorption, near-field enhancement, and high sensitivity to the external environment. Therefore, they have important application value in fields such as smart windows, photothermal therapy, catalysis, and sensing.

[0003] Glass, due to its weak solar radiation blocking properties, is one of the main channels for buildings to gain and release heat. However, with the increasing demands of modern buildings for outdoor views and indoor lighting, large-area glass windows or glass curtain wall structures are often used. Therefore, the development of a membrane that can be coated onto ordinary glass will result in a new type of energy-saving material with good light transmission and high heat insulation performance, which will be of great significance for building energy conservation. Researchers have discovered that semiconductors can introduce LSPR (Laser-Lasting Resonance Propagation) through antimony doping, interstitial doping, and substitution doping, and the peak position can be controlled by different shapes, sizes, and dopant concentrations. Common LSPR semiconductors include antimony or indium-doped tin oxide, tungsten bronze, and copper sulfide. However, the LSPR absorption of tin oxide appears above 1500nm, and the application of tungsten bronze and copper sulfide is affected by high cost and instability, respectively. Therefore, finding alternative semiconductors based on abundant Earth resources and non-toxicity is of great significance. The wide-bandgap semiconductor TiO2 has attracted the attention of researchers due to its green and non-toxic properties, chemical stability, and simple preparation method. Studies have shown that TiO2... 4+ Site and O 2- Introducing substitutes of different valences, such as Nb, at the site. 5+ W 6+ Mo 5+ Ta 5+ Free carriers are generated in the conduction band of TiO2 and exhibit LSPR properties. It can absorb light to a certain extent in some near-infrared bands, thus having near-infrared shielding heat insulation properties.

[0004] Chinese invention patent application 202210577452.0 discloses a transparent heat-insulating material of fluorotungsten titanium dioxide and its preparation method. The material uses octadecyl alcohol or hexadecyl alcohol as a solvent, octadecene or n-tetradecene as a surfactant, and oleic acid and oleylamine as morphology control agents. These are mixed in a titanium source, a fluorine source, and a tungsten source substrate. The mixture is stirred and heated uniformly under a nitrogen atmosphere until the solid particles in the raw material dissolve, followed by degassing. The temperature is then raised to 300-330℃ and held for 1-2 hours, followed by cooling, washing, drying, and grinding to obtain the final product. This invention utilizes fluorotungsten ion doping of titanium dioxide, because W... 6+ High price state for Ti 4+ With the substitution of , the fluorotungsten nano-titanium dioxide sample showed local surface plasmon resonance absorption at 1200 nm in the near-infrared region. However, since the absorbance at the peak position was about 0.4-0.5, the near-infrared absorption effect was not significant, resulting in poor near-infrared shielding effect. Moreover, since the LSPR peak position in fluorotungsten titanium dioxide was basically fixed, it was difficult to achieve peak position control.

[0005] Early diagnosis of diseases is crucial for timely treatment and improving patient survival rates. Fluorescence imaging, due to its absence of ionizing radiation, lack of radiotoxicity, and superior imaging characteristics, has attracted widespread attention and is a rapidly developing in vivo imaging modality. Academician Hongjie Dai of Stanford University discovered that the optical biological tissue window in the near-infrared II region (1000-1700nm) is superior to the traditional near-infrared I region (700-900nm). Firstly, water absorption is greater in this band, which can reduce background noise from scattered signal photons in wide-field imaging techniques. Secondly, light scattering is less in this band, allowing for greater penetration depth within the organism, enabling the acquisition of images of deeper layers within the body. Fluorescence bioimaging above 1300 nm is superior to fluorescence bioimaging in the 900-1300 nm range (short wavelength region of NIR-II). The redshift-induced scattering suppression and absorption surge after 1300 nm contribute to background attenuation, with less absorption and scattering of excitation and emission light, resulting in better in vivo imaging. Among these, vascular imaging at 1425–1475 nm has the lowest imaging background, and 1550–1700 nm is the region with the lowest photon scattering. Therefore, optical signals in the near-infrared II region can greatly improve the penetration depth, resolution, and signal-to-noise ratio of in vivo imaging, making it highly practical in biological and medical sciences.

[0006] Chinese invention patent application 202310850917.X discloses a fluorescent emitter, preparation method, and imaging system for HeLa cell imaging. It modulates the LSPR peak position by changing the size of silver particles and coats fluorescent dyes on the outside of the silver nanoparticles. Through LSPR and strong coupling effects, a fluorescent emitter with precisely tunable emission wavelength and the ability to eliminate external interference factors is prepared. However, the corresponding wavelength of silver is in the NIR-I region, where the internal fixation of high charge carriers makes further modulation difficult. Huang Zhongyu synthesized gold nanoneedles with LSPR absorption peaks in the NIR-II region using a one-step method to enhance the signal intensity during cell imaging. Studies show that gold nanoneedles with peaks at 1104 nm and in the 1425-1475 nm band both obtained cell images with high SBR. Water absorption is significant in this band, which is rarely used for biofluorescence imaging. However, under the enhancement effect of the LSPR effect, better imaging results can be obtained in this band, compensating for the shortcomings of fluorescence imaging in bioimaging. Gold materials are expensive, and their internal carrier concentration is basically fixed, making it difficult to control the peak position of LSPR. Therefore, titanium oxide materials that can achieve wide-range control of the LSPR effect in the near-infrared II region have great application prospects. Summary of the Invention

[0007] The purpose of this invention is to provide a core-shell structured titanium dioxide solid solution material that combines strong absorption with a wide range of tunable LSPR effect, thereby overcoming the limitations of current technologies where doping introduces localized surface plasmon resonance absorption, resulting in weak absorption intensity in the near-infrared region and difficulty in controlling the peak position in the near-infrared II region.

[0008] Another objective of this invention is to provide a core-shell structured titanium dioxide solid solution material with both strong absorption and wide-range tunable LSPR effect for the preparation of transparent heat-insulating coatings and for replacing Au and Ag in the preparation of NIR-II nanoprobes; to improve the performance of titanium dioxide materials in heat-insulating glass; and to enhance the tunability of the peak position of NIR-II nanoprobes in the near-infrared II region for application in the field of biofluorescence imaging.

[0009] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0010] A core-shell structured titanium dioxide solid solution material exhibiting both strong absorption and wide-range tunable LSPR effect is characterized by: a core-shell structure with fluorotungsten titanium dioxide solid solution nanoparticles as the core and fluoroniobium titanium dioxide solid solution as the shell; the fluorotungsten titanium dioxide solid solution is synthesized by ammonolysis reaction after degassing the core precursor and tungsten source; the core-shell structure is obtained by injecting the shell precursor and niobium source into the fluorotungsten titanium dioxide solid solution, degassing, and then reacting at 280℃-330℃ to synthesize the outer shell fluoroniobium titanium dioxide solid solution, which is then coated onto the surface of the fluorotungsten titanium dioxide solid solution core nanoparticles, cooled to room temperature, centrifuged, washed, and dried; the raw materials for the core or shell precursor consist of an alcohol source, a reaction solvent, a morphology control agent, a titanium source, and a fluorine source.

[0011] To further achieve the objectives of this invention, preferably, the alcohol source is one or more of octadecyl alcohol, hexadecyl alcohol, and dodecanol; the morphology control agent is one or more of oleic acid and oleylamine; and the reaction solvent is one or more of octadecene and tetradecene.

[0012] Preferably, the titanium source is one or more of tetraethyl titanate, isopropyl titanate, titanium tetrachloride, and titanium n-butoxide; the tungsten source is one or more of tungsten hexachloride, tungsten pentachloride, ammonium tungstate, and sodium tungstate; the niobium source is niobium pentachloride; and the fluorine source is one or more of sodium fluoride, potassium fluoride, ammonium fluoride, and hydrofluoric acid.

[0013] Preferably, the molar ratio of alcohol source: fluorine source: titanium source is (150-300):(2-10):20; and the volume ratio of morphology control agent, reaction solvent and titanium source is (2-15):(20-200):1.

[0014] Preferably, the molar ratio of the tungsten source to the titanium source is (1-4):10.

[0015] Preferably, the molar ratio of niobium source to titanium source is (1-5):10.

[0016] Preferably, the molar ratio of tungsten source to niobium source is (1-1):(1-5).

[0017] Preferably, the ammonolysis reaction is carried out under a nitrogen atmosphere at a temperature of 280℃-300℃ for 60-90 minutes; the reaction time at 280℃-330℃ is 60-90 minutes; the degassing in the degassing of the nuclear precursor and tungsten source, or the degassing in the reaction at 280℃-330℃ after degassing, is carried out in a vacuum at 100℃-140℃ for 20-40 minutes.

[0018] The cooling described is natural cooling to room temperature;

[0019] The centrifugal washing process involves dissolving the product in hexane and cooling it to room temperature, then reprecipitating the dissolved product with acetone and ethanol, wherein the volume ratio of hexane, acetone and ethanol is (1-2):5:4. The product is then heated to 50-60°C and held for 5-15 minutes, and centrifuged at 5000-12000 r / min. This process is repeated 4-6 times.

[0020] The drying process involves drying in a vacuum drying chamber at 60-80℃ for 12-24 hours.

[0021] The preparation method of the core-shell structured titanium dioxide solid solution material with both strong absorption and wide-range tunable LSPR effect includes the following steps:

[0022] 1) Fluorotungsten titanium oxide solid solution nanoparticles were synthesized by degassing the nuclear precursor and tungsten source and then reacting them with ammonolysis.

[0023] 2) The shell precursor and niobium source were injected into the fluorotungsten titanium oxide solid solution. After degassing, the outer shell fluoroniobium titanium oxide solid solution was synthesized at 280℃-330℃ and coated on the surface of the core nanoparticles to form a core-shell structure with fluorotungsten titanium oxide solid solution as the core and fluoroniobium titanium oxide solid solution as the shell.

[0024] 3) Cool the core-shell structure to room temperature, centrifuge, wash, and dry to obtain a core-shell structured titanium dioxide solid solution material with both strong absorption and wide-range tunable LSPR effect.

[0025] The core-shell structured titanium dioxide solid solution material, which combines strong absorption and wide-range tunable LSPR effect, is used in the preparation of transparent heat-insulating coatings and in the preparation of NIR-II nanoprobes as a substitute for Au and Ag.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1) The core-shell structure prepared by this invention can improve near-infrared absorption absorbance and broaden the absorption range. Compared with the prior art, it further enhances the near-infrared blocking rate and improves the heat insulation effect.

[0028] 2) The core-shell structure prepared by this invention combines the near-infrared absorption of the core and the far-infrared absorption of the shell. By utilizing the concentration and distribution of dopants to regulate the local surface plasmons, the limitation of the LSPR peak position being difficult to control is solved, which greatly enhances the near-infrared response band of the core-shell titanium dioxide solid solution and is expected to be applied in fields such as biological fluorescence imaging.

[0029] 3) The preparation process of the core-shell structure of the present invention is simple. The shell material is quickly poured into the fluorotungsten titanium oxide solid solution of the core and reacted fully at high temperature. No complicated equipment or extreme reaction conditions are required. Attached Figure Description

[0030] Figure 1 The X-ray diffraction patterns are of the products obtained in Comparative Example 1, Example 1, Example 2, Example 3, Example 4, and Example 5.

[0031] Figure 2 The X-ray photoelectron spectra of the products obtained in Comparative Example 1 and Example 3 are shown.

[0032] Figure 3 These are X-ray photoelectron spectra of samples etched to different depths obtained in Example 3.

[0033] Figure 4(a) shows the UV-Vis-NIR absorption spectra of Example 1 in different solvents; Figure 4(b) shows the relationship between the LSPR absorption peaks in different solvents in Figure 4(a) and the dielectric constant of the solvent.

[0034] Figure 5(a) shows the UV-Vis and near-infrared absorption spectra of the products obtained in Comparative Example 1, Example 1, Example 2, Example 3, Example 4, and Example 5; Figure 5(b) is a smoothed magnified view of the peak positions of the curve in Figure 5(a).

[0035] Figure 6 The transmission spectrum of the powder obtained in Comparative Example 1 and Example 3 after being prepared into a thin film is shown.

[0036] Figure 7 The diagram shows the temperature change inside the heat insulation device after the powders obtained in Comparative Example 1 and Example 3 are used to prepare thin films. Detailed Implementation

[0037] The present invention will be further described below with reference to the embodiments and accompanying drawings. The embodiments are used to illustrate and explain the present invention, but the implementation of the present invention is not limited thereto.

[0038] Although fluorotungsten-titanium oxide solid solutions exhibit significant LSPR absorption in the near-infrared region, enhancing the infrared absorption performance of TiO2 to some extent, their absorbance in the near-infrared region is low, and the peak position is stable within the 1180nm-1230nm range, making tuning difficult. Synthesizing titanium dioxide nanoparticles with controllable LSPR properties remains a challenge. A wide-band tunable LSPR effect in the near-infrared region allows for full utilization of sunlight, which is significant for near-infrared photocatalysis, near-infrared photothermal therapy, near-infrared photodetectors, and energy-saving windows. Therefore, exploring a core-shell structured titanium oxide solid solution with strong absorption in the near-infrared II region and a wide-range tunable LSPR effect is of great importance.

[0039] This invention discovers that if a fluorinated niobium titanium oxide solid solution and a fluorinated tungsten titanium oxide solid solution, which have absorption in the mid-infrared and near-infrared regions respectively, are combined and a core-shell structure is formed by hot injection, a nano-titanium oxide with stronger absorption in the near-infrared region can be obtained due to the superposition of the properties of the two materials and the regulation of carrier concentration by the core-shell structure. This effectively improves the near-infrared absorption performance of the material. In the process of changing the core-shell ratio, the peak position in the near-infrared II region and the absorbance can be adjusted.

[0040] Therefore, this invention provides a core-shell structured titanium dioxide solid solution material with both strong absorption and wide-range LSPR effect regulation. The core-shell structure uses a fluorotungsten titanium dioxide solid solution as the core and a fluoroniobium titanium dioxide solid solution as the shell. The fluorotungsten titanium dioxide solid solution is synthesized by ammonolysis after degassing the core precursor and tungsten source. The core-shell structure is obtained by injecting the shell precursor and niobium source into the fluorotungsten titanium dioxide solid solution, degassing, and then reacting at 280℃-330℃ to synthesize the outer shell fluoroniobium titanium dioxide solid solution, which is then coated onto the surface of the fluorotungsten titanium dioxide solid solution core nanoparticles. The mixture is then cooled to room temperature, centrifuged, washed, and dried. The raw materials for the core or shell precursor consist of an alcohol source, a reaction solvent, a morphology control agent, a titanium source, and a fluorine source. The core of this technical measure is the synthesis of the outer shell fluorine-niobium titanium oxide solid solution and the core-shell structure formed by encapsulating the core nanoparticles of fluorine-tungsten titanium oxide solid solution. As for the preparation of the fluorine-tungsten titanium oxide solid solution itself, as well as the composition of the raw materials of the core precursor or shell precursor, such as the alcohol source, reaction solvent, morphology control agent, titanium source, and fluorine source, the alcohol source, reaction solvent, morphology control agent, titanium source, and fluorine source can be determined based on the existing technology according to the purpose of the invention.

[0041] This invention eliminates the need for purifying the fluorotungsten titanium oxide solid solution. Instead, a degassed and dissolved shell precursor and niobium source are rapidly poured into the fluorotungsten titanium oxide solid solution. Preferably, more than 100 ml of the shell precursor and niobium source are poured into the fluorotungsten titanium oxide solid solution within 60 seconds, resulting in nanocrystals with a more uniform morphology and narrower size distribution. The molar ratio of tungsten source to titanium source is preferably controlled at (1-4):(10), where the core fluorotungsten titanium oxide solid solution exhibits an absorption peak at 1180 nm-1230 nm, with an absorbance of approximately 0.4-0.5. Alternatively, the molar ratio of niobium source to titanium source is preferably controlled at (1-5):(10), where the outer shell fluoroniobium titanium oxide solid solution exhibits absorption in the mid-to-far infrared band, with absorbance gradually increasing from 0.1 to approximately 0.8, and an absorption peak at 3300 nm-3400 nm.

[0042] The LSPR peak position of the core-shell structured titanium dioxide solid solution prepared by this invention can be tuned over a wide range of 1180nm-1725nm in the near-infrared region, which is expected to improve the near-infrared imaging window for disease detection and enhance imaging quality. Thin films prepared using the nano-titanium dioxide solid solution material of this invention, which combines strong absorption and a wide range of LSPR modulation, exhibit excellent transparent and heat-insulating properties, with a near-infrared blocking rate of 74.3%.

[0043] Utilizing the strong absorption characteristics of the core-shell structured titanium dioxide solid solution material in the near-infrared region, which possesses both strong absorption and a wide-range tunable LSPR effect, a transparent heat-insulating coating can be prepared for use in building energy conservation. Furthermore, since the LSPR effect amplifies signals, the core-shell structured titanium dioxide solid solution material, capable of achieving a wide-range tunable LSPR effect from 1185nm to 1725nm in the near-infrared II region, holds promise as a replacement for expensive and difficult-to-control Au materials, becoming a new material for NIR-II nanoprobes. This could improve the penetration depth, resolution, and signal-to-noise ratio of in vivo imaging, broaden the imaging range, and enhance imaging quality.

[0044] The transmittance of the prepared film was tested using a UV-Vis-NIR spectrophotometer. 0.1 g of nano-titanium oxide solid solution was dispersed in 15 g of toluene solution and ultrasonically dispersed for 10-15 min. After stirring for approximately 2-3 min, 0.5 g of ethyl cellulose powder and 1 ml of ethanol solution were added to the dispersion, followed by vigorous stirring for 30-60 min. After stirring, the mixture was allowed to stand for 3-5 min to remove air bubbles generated during stirring. Finally, the mixture was poured into the center of a 10×10 cm glass container using a self-leveling method and allowed to air dry for 10 h. The transmittance of the film was then measured using a UV-Vis-NIR spectrophotometer, and the near-infrared blocking rate was calculated. The near-infrared wavelength was 780-2500 nm.

[0045] Near-infrared light blocking rate R of thin film NIR The calculation formula is:

[0046]

[0047] In the formula, T(λ) is the transmittance measured by the spectrophotometer, and i(λ) is the solar spectral radiation intensity (ASTM standard G173).

[0048] The thermal insulation performance of the prepared film was tested using an insulated chamber. The chamber was constructed by bonding foam material (polystyrene) with adhesive and cutting it into cubes measuring 20×20×20cm. A 10×10cm square slit was made at the top of the chamber, and a digital thermometer was inserted into the right side. The specific testing method involved placing the film sample at the 10×10cm slit and using a 150W infrared lamp to simulate sunlight, positioned 40cm directly above the film sample. Temperature was recorded every 5 minutes for a total of 120 minutes.

[0049] Example 1

[0050] The preparation method of core-shell structured titanium dioxide solid solution materials with both strong absorption and wide-range tunable LSPR effect is as follows:

[0051] Weigh 100 mmol of octadecyl alcohol, 80 ml of octadecene, 5 ml of oleylamine, 5 ml of oleic acid, 10 mmol of isopropyl titanate solution, 3 mmol of ammonium fluoride powder (consisting of a nuclear precursor), and 2 mmol of tungsten hexachloride powder into a 500 ml three-necked flask. Place the three-necked flask in a heated magnetic stirrer and heat it in an oil bath while stirring. Nitrogen gas is introduced during the heating process. When all the solid particles in the three-necked flask have dissolved and the temperature reaches 120 °C, stop the nitrogen gas introduction and maintain the temperature at 120 °C. Perform vacuum degassing treatment in a sealed environment for 20 min, continue to introduce nitrogen gas and heat until the temperature rises to 300 °C and is held for 1 h to obtain a fluorotungsten titanium oxide solid solution.

[0052] Weigh 100 mmol of octadecyl alcohol, 80 ml of octadecene, 5 ml of oleylamine, 5 ml of oleic acid, 10 mmol of tetraethyl titanate solution, 3 mmol of ammonium fluoride powder (comprising a shell precursor), and 2 mmol of niobium pentachloride powder into a 500 ml three-necked flask. Place the three-necked flask in a heated magnetic stirrer and heat it in an oil bath while stirring. Nitrogen gas is introduced during the heating process. When all the solid particles in the three-necked flask have dissolved and the temperature reaches 120 °C, stop the nitrogen gas introduction and maintain the temperature at 120 °C. After vacuum degassing in a sealed environment for 20 min, quickly pour the solution into a 300 °C fluorotungsten titanium oxide solid solution. After the temperature rises back to 300 °C, keep it at that temperature for 1 h to complete the synthesis of the fluoroniobium titanium oxide solid solution and the coating on the core surface, resulting in a core-shell structured titanium oxide solid solution with a fluorotungsten titanium oxide solid solution as the core and a fluoroniobium titanium oxide solid solution as the shell.

[0053] After the reaction was completed, the product was naturally cooled to 50°C, precipitated with an equal volume of acetone solution, and then heated at 60°C for 10 min, followed by centrifugation at 5000 r / min. The precipitate was then dissolved in a mixture of hexane, acetone and ethanol in a volume ratio of 1:5:4, heated at 60°C for 10 min, and centrifuged at 5000 r / min for a second time. This process was repeated four times to obtain a core-shell structured titanium dioxide solid solution material. 0.02 g of the core-shell structured titanium dioxide solid solution material was weighed and dispersed in 10 ml of tetrachloroethylene and subjected to UV-Vis-NIR absorption testing.

[0054] 0.1g of core-shell structured titanium dioxide solid solution was dispersed in 15g of toluene solution. After ultrasonic dispersion for 15min, the mixture was stirred for about 3min. Then, 0.5g of ethyl cellulose powder and 10ml of ethanol solution were added to the dispersion, and stirring was continued for 30min. After stirring, the mixture was allowed to stand for 5min to remove air bubbles generated during stirring. Finally, the mixture was poured into the center of a 10×10cm glass using a self-leveling method. After natural drying for about 60min to further stabilize the film, it was transferred to a 60℃ oven for drying for 35min. After drying, the transmittance of the film was tested using a UV-Vis-NIR spectrophotometer, and the near-infrared blocking rate was calculated. The near-infrared blocking rate of the obtained sample was 64.2%.

[0055] Example 2

[0056] The preparation method of core-shell structured titanium dioxide solid solution materials with both strong absorption and wide-range tunable LSPR effect is as follows:

[0057] Weigh 66.7 mmol of octadecyl alcohol, 53 ml of octadecene, 6.6 ml of oleylamine, 6.67 mmol of isopropyl titanate solution, 2 mmol of ammonium fluoride powder (consisting of a nuclear precursor), and 1.33 mmol of tungsten hexachloride powder into a 500 ml three-necked flask. Place the three-necked flask in a heated magnetic stirrer and heat it in an oil bath while stirring. Nitrogen gas is introduced during the heating process. When all the solid particles in the three-necked flask have dissolved and the temperature reaches 120 °C, stop the nitrogen gas introduction and maintain the temperature at 120 °C. Perform vacuum degassing treatment in a sealed environment for 20 min, continue to introduce nitrogen gas and heat until the temperature rises to 300 °C and is held for 1 h to obtain a fluorotungsten titanium oxide solid solution.

[0058] Weigh 133.3 mmol of octadecyl alcohol, 106.6 ml of octadecene, 13.4 ml of oleylamine, 13.33 mmol of isopropanol titanate solution, 4 mmol of ammonium fluoride powder (comprising a shell precursor), and 2.66 mmol of niobium pentachloride powder into a 500 ml three-necked flask. Place the three-necked flask in a heated magnetic stirrer and heat it in an oil bath while stirring. Nitrogen gas is introduced during the heating process. When all the solid particles in the three-necked flask have dissolved and the temperature reaches 120 °C, stop the nitrogen gas introduction and maintain the temperature at 120 °C. After vacuum degassing in a sealed environment for 20 min, quickly pour the solution into a 300 °C fluorotungsten titanium oxide solid solution. After the temperature rises back to 300 °C, keep it at that temperature for 1 h to complete the synthesis of the fluoroniobium titanium oxide solid solution and the coating on the core surface, resulting in a core-shell structured titanium oxide solid solution with a fluorotungsten titanium oxide solid solution as the core and a fluoroniobium titanium oxide solid solution as the shell.

[0059] After the reaction was completed, the product was naturally cooled to 50°C, precipitated with an equal volume of acetone solution, and then heated at 60°C for 10 min, followed by centrifugation at 5000 r / min. The precipitate was then dissolved in a mixture of hexane, acetone and ethanol in a volume ratio of 1:5:4, heated at 60°C for 10 min, and centrifuged at 5000 r / min for a second time. This process was repeated four times to obtain a core-shell structured titanium dioxide solid solution material. 0.02 g of the core-shell structured titanium dioxide solid solution material was weighed and dispersed in 10 ml of tetrachloroethylene and subjected to UV-Vis-NIR absorption testing.

[0060] 0.1g of core-shell structured titanium dioxide solid solution was dispersed in 15g of toluene solution. After ultrasonic dispersion for 15min, the mixture was stirred for about 3min. Then, 0.5g of ethyl cellulose powder and 10ml of ethanol solution were added to the dispersion, and stirring was continued for 30min. After stirring, the mixture was allowed to stand for 5min to remove air bubbles generated during stirring. Finally, the mixture was poured into the center of a 10×10cm glass using a self-leveling method. After natural drying for about 60min to further stabilize the film, it was transferred to a 60℃ oven for drying for 35min. After drying, the transmittance of the film was tested using a UV-Vis-NIR spectrophotometer, and the near-infrared blocking rate was calculated. The near-infrared blocking rate of the obtained sample was 68.3%.

[0061] Example 3

[0062] The preparation method of core-shell structured titanium dioxide solid solution materials with both strong absorption and wide-range tunable LSPR effect is as follows:

[0063] Weigh out 57 mmol of octadecyl alcohol, 45.7 ml of octadecene, 2.86 ml of oleylamine and 2.86 ml of oleic acid, 5.71 mmol of isopropyl titanate solution, 1.71 mmol of ammonium fluoride powder (consisting of a nuclear precursor), and 1.14 mmol of tungsten hexachloride powder, and add them to a 500 ml three-necked flask. Place the three-necked flask in a heated magnetic stirrer and heat it in an oil bath while stirring. Nitrogen gas is introduced during the heating process. When all the solid particles in the three-necked flask have dissolved and the temperature reaches 120 °C, stop the nitrogen gas introduction and maintain the temperature at 120 °C. Perform vacuum degassing treatment in a sealed environment for 20 min, continue to introduce nitrogen gas and heat, and hold the temperature at 300 °C for 1 h to obtain fluorotungsten titanium oxide solid solution.

[0064] Weigh 143 mmol of octadecyl alcohol, 114.3 ml of octadecene, 7.14 ml of oleylamine and 7.14 ml of oleic acid, 14.29 mmol of isopropyl titanate solution, and 4.28 mmol of ammonium fluoride powder (forming a shell precursor) and 2.86 mmol of niobium pentachloride powder into a 500 ml three-necked flask. Place the three-necked flask in a heated magnetic stirrer and heat it in an oil bath while stirring. Nitrogen gas is introduced during the heating process. When all the solid particles in the three-necked flask have dissolved and the temperature reaches 120 °C, stop the nitrogen gas introduction and maintain the temperature at 120 °C. After vacuum degassing in a sealed environment for 20 min, quickly pour the solution into a 300 °C fluorotungsten titanium oxide solid solution. After the temperature rises back to 300 °C, keep it at that temperature for 1 h to complete the synthesis of the fluoroniobium titanium oxide solid solution and the coating on the core surface, resulting in a core-shell structured titanium oxide solid solution with a fluorotungsten titanium oxide solid solution as the core and a fluoroniobium titanium oxide solid solution as the shell.

[0065] After the reaction was completed, the product was naturally cooled to 50°C, precipitated with an equal volume of acetone solution, and then heated at 60°C for 10 min, followed by centrifugation at 5000 r / min. The precipitate was then dissolved in a mixture of hexane, acetone and ethanol in a volume ratio of 1:5:4, heated at 60°C for 10 min, and centrifuged at 5000 r / min for a second time. This process was repeated four times to obtain a core-shell structured titanium dioxide solid solution material. 0.02 g of the core-shell structured titanium dioxide solid solution material was weighed and dispersed in 10 ml of tetrachloroethylene and subjected to UV-Vis-NIR absorption testing.

[0066] 0.1g of core-shell structured titanium dioxide solid solution was dispersed in 15g of toluene solution. After ultrasonic dispersion for 15min, the mixture was stirred for about 3min. Then, 0.5g of ethyl cellulose powder and 10ml of ethanol solution were added to the dispersion, and stirring was continued for 30min. After stirring, the mixture was allowed to stand for 5min to remove air bubbles generated during stirring. Finally, the mixture was poured into the center of a 10×10cm glass using a self-leveling method. After natural drying for about 60min to further stabilize the film, it was transferred to a 60℃ oven for drying for 35min. After drying, the transmittance of the film was tested using a UV-Vis-NIR spectrophotometer, and the near-infrared blocking rate was calculated. The near-infrared blocking rate of the obtained sample was 74.3%.

[0067] Example 4

[0068] The preparation method of core-shell structured titanium dioxide solid solution materials with both strong absorption and wide-range tunable LSPR effect is as follows:

[0069] Weigh out 50 mmol of cetyl alcohol, 40 ml of tetradecene, 2.5 ml of oleylamine and 2.5 ml of oleic acid, 5 mmol of tetraethyl titanate solution, a nucleus precursor composed of 1.5 mmol of sodium fluoride powder, and 1 mmol of ammonium tungstate powder, and add them to a 500 ml three-necked flask. Place the three-necked flask in a heated magnetic stirrer and heat it in an oil bath while stirring. Nitrogen gas is introduced during the heating process. When all the solid particles in the three-necked flask have dissolved and the temperature reaches 120 °C, stop the nitrogen gas introduction and maintain the temperature at 120 °C. Perform vacuum degassing in a sealed environment for 20 min, then continue to introduce nitrogen gas and heat until the temperature rises to 300 °C and is held for 1 h to obtain a fluorotungsten titanium oxide solid solution.

[0070] Weigh 150 mmol cetyl alcohol, 120 ml tetradecene, 7.5 ml oleylamine, 7.5 ml oleic acid, 15 mmol tetraethyl titanate solution, and 4.5 mmol ammonium fluoride powder (forming a shell precursor) and 3 mmol niobium pentachloride powder into a 500 ml three-necked flask. Place the three-necked flask in a heat-collecting constant-temperature magnetic stirrer for oil bath heating and stirring, with nitrogen gas introduced during heating. When all the solid particles in the three-necked flask have dissolved and the temperature reaches 120 °C, stop the nitrogen gas introduction and maintain the temperature at 120 °C. After vacuum degassing in a sealed environment for 20 min, quickly pour the solution into a 300 °C fluorotungsten titanium oxide solid solution. After the temperature rises back to 300 °C, maintain the temperature for 1 h to complete the synthesis of the fluoroniobium titanium oxide solid solution and the coating on the core surface, obtaining a core-shell structured titanium oxide solid solution with a fluorotungsten titanium oxide solid solution as the core and a fluoroniobium titanium oxide solid solution as the shell.

[0071] After the reaction was completed, the product was naturally cooled to 50°C, precipitated with an equal volume of acetone solution, and then heated at 60°C for 10 min, followed by centrifugation at 5000 r / min. The precipitate was then dissolved in a mixture of hexane, acetone and ethanol in a volume ratio of 1:5:4, heated at 60°C for 10 min, and centrifuged at 5000 r / min for a second time. This process was repeated four times to obtain a core-shell structured titanium dioxide solid solution material. 0.02 g of the core-shell structured titanium dioxide solid solution material was weighed and dispersed in 10 ml of tetrachloroethylene and subjected to UV-Vis-NIR absorption testing.

[0072] 0.1g of core-shell structured titanium dioxide solid solution was dispersed in 15g of toluene solution. After ultrasonic dispersion for 15min, the mixture was stirred for about 3min. Then, 0.5g of ethyl cellulose powder and 10ml of ethanol solution were added to the dispersion, and stirring was continued for 30min. After stirring, the mixture was allowed to stand for 5min to remove air bubbles generated during stirring. Finally, the mixture was poured into the center of a 10×10cm glass using a self-leveling method. After natural drying for about 60min to further stabilize the film, it was transferred to a 60℃ oven for drying for 35min. After drying, the transmittance of the film was tested using a UV-Vis-NIR spectrophotometer, and the near-infrared blocking rate was calculated. The near-infrared blocking rate of the obtained sample was 70.8%.

[0073] Example 5

[0074] The preparation method of core-shell structured titanium dioxide solid solution materials with both strong absorption and wide-range tunable LSPR effect is as follows:

[0075] Weigh 44.5 mmol of octadecyl alcohol, 35.6 ml of octadecene, 2.22 ml of oleylamine and 2.22 ml of oleic acid, 4.44 mmol of tetraethyl titanate solution, 1.33 mmol of sodium fluoride powder (consisting of a nuclear precursor), and 0.89 mmol of tungsten hexachloride powder into a 500 ml three-necked flask. Place the three-necked flask in a heated magnetic stirrer and heat it in an oil bath while stirring. Nitrogen gas is introduced during the heating process. When all the solid particles in the three-necked flask have dissolved and the temperature reaches 120 °C, stop the nitrogen gas introduction and maintain the temperature at 120 °C. Perform vacuum degassing treatment in a sealed environment for 20 min, continue to introduce nitrogen gas and heat until the temperature rises to 300 °C and is held for 1 h to obtain a fluorotungsten titanium oxide solid solution.

[0076] Weigh 155.5 mmol of octadecyl alcohol, 124.4 ml of octadecene, 7.78 ml of oleylamine and 7.78 ml of oleic acid, 15.56 mmol of tetraethyl titanate solution, and 4.67 mmol of sodium fluoride powder (forming a shell precursor) and 3.11 mmol of niobium pentachloride powder into a 500 ml three-necked flask. Place the three-necked flask in a heated magnetic stirrer and heat it in an oil bath while stirring. Nitrogen gas is introduced during the heating process. When all the solid particles in the three-necked flask have dissolved and the temperature reaches 120 °C, stop the nitrogen gas introduction and maintain the temperature at 120 °C. After vacuum degassing in a sealed environment for 20 min, quickly pour the solution into a 300 °C fluorotungsten titanium oxide solid solution. After the temperature rises back to 300 °C, keep it at that temperature for 1 h to complete the synthesis of the fluoroniobium titanium oxide solid solution and the coating on the core surface, resulting in a core-shell structured titanium oxide solid solution with a fluorotungsten titanium oxide solid solution as the core and a fluoroniobium titanium oxide solid solution as the shell.

[0077] After the reaction was completed, the product was naturally cooled to 50°C, precipitated with an equal volume of acetone solution, and then heated at 60°C for 10 min, followed by centrifugation at 5000 r / min. The precipitate was then dissolved in a mixture of hexane, acetone and ethanol in a volume ratio of 1:5:4, heated at 60°C for 10 min, and centrifuged at 5000 r / min for a second time. This process was repeated four times to obtain a core-shell structured titanium dioxide solid solution material. 0.02 g of the core-shell structured titanium dioxide solid solution material was weighed and dispersed in 10 ml of tetrachloroethylene and subjected to UV-Vis-NIR absorption testing.

[0078] 0.1g of core-shell structured titanium dioxide solid solution was dispersed in 15g of toluene solution. After ultrasonic dispersion for 15min, the mixture was stirred for about 3min. Then, 0.5g of ethyl cellulose powder and 10ml of ethanol solution were added to the dispersion, and stirring was continued for 30min. After stirring, the mixture was allowed to stand for 5min to remove air bubbles generated during stirring. Finally, the mixture was poured into the center of a 10×10cm glass using a self-leveling method. After natural drying for about 60min to further stabilize the film, it was transferred to a 60℃ oven for drying for 35min. After drying, the transmittance of the film was tested using a UV-Vis-NIR spectrophotometer, and the near-infrared blocking rate was calculated. The near-infrared blocking rate of the obtained sample was 66%.

[0079] Comparative Example 1

[0080] A method for preparing a fluorotungsten-titanium oxide solid solution with absorption in the near-infrared II region, comprising the following steps:

[0081] 1) Weigh 100 mmol octadecyl alcohol, 80 ml octadecene, 5 ml oleylamine and 5 ml oleic acid and add them to a 250 ml three-necked flask. Then add 10 mmol tetraethyl titanate solution, 3 mmol ammonium fluoride powder and 2 mmol tungsten hexachloride powder to the three-necked flask in sequence.

[0082] 2) Place the three-necked flask into a heat-collecting, constant-temperature magnetic stirrer for oil bath heating and stirring, and introduce nitrogen gas during the heating process;

[0083] 3) After all the solid particles in the three-necked flask have dissolved and the temperature has reached 120°C, stop the nitrogen flow and maintain the temperature at 120°C for 20 minutes of vacuum degassing in a sealed environment.

[0084] 4) After the previous step is completed, continue to purge with nitrogen and heat until the temperature reaches 300℃, then keep it at that temperature for 1 hour. After the reaction is complete, allow the product to cool naturally to 50℃, dissolve it in an equal volume of acetone solution, then heat it at 60℃ for 10 minutes, followed by centrifugation at 5000 r / min for the first time; the resulting precipitate is then dissolved in a mixture of n-hexane, acetone and ethanol in a volume ratio of 1:3:3, heated at 60℃ for 10 minutes, and centrifuged a second time at 5000 r / min. Repeat this process 4 times to obtain the fluorotungsten titanium oxide solid solution material. Weigh 0.02 g of the powder, disperse it in 10 ml of tetrachloroethylene, and perform ultraviolet-visible-near-infrared absorption tests.

[0085] 0.1g of fluorotungsten-titanium oxide solid solution was dispersed in 15g of toluene solution. After ultrasonic dispersion for 15min, the mixture was stirred for approximately 3min. Then, 0.5g of ethyl cellulose powder and 10ml of ethanol solution were added to the dispersion, and stirring continued for 30min. After stirring, the mixture was allowed to stand for 5min to remove air bubbles generated during stirring. Finally, the mixture was poured into the center of a 10×10cm glass container using a self-leveling method. After natural drying for approximately 60min to further stabilize the film, it was transferred to a 60℃ oven for drying for 35min. After drying, the transmittance of the film was tested using a UV-Vis-NIR spectrophotometer, and the near-infrared blocking rate was calculated. The obtained sample... The near-infrared blocking rate was determined by ultrasonic dispersion for 10-15 minutes followed by stirring. After stirring for about 2-3 minutes, 0.5 g of ethyl cellulose powder and 10 ml of ethanol solution were added to the dispersion, and stirring was continued for 30-40 minutes. After stirring, the mixture was allowed to stand for 3-5 minutes to remove air bubbles generated during stirring. Finally, the mixture was poured into the center of a 10×10 cm glass using a self-leveling method and allowed to air dry for about 60 minutes until the film was further stabilized. Then, it was transferred to a 60℃ oven to dry for 30-40 minutes. After drying, the transmittance of the film was tested using a UV-Vis-NIR spectrophotometer, and the near-infrared blocking rate was calculated. The obtained near-infrared blocking rate was 61%.

[0086] Figure 1 for Figure 1 For the X-ray diffraction patterns of Comparative Example 1 and Examples 1, 2, 3, 4, and 5, the XRD diffraction peak data all correspond to the diffraction peaks of anatase titanium dioxide (JCPDS:21-1272). No new diffraction peaks appeared in the core-shell structure, that is, the phase does not contain rutile phase and brookite phase.

[0087] Figure 2 The X-ray photoelectron spectroscopy of Comparative Example 1 and Example 3 both showed the presence of Ti, O, and C elements, with C being the reference material. The presence of fluorine and tungsten in Comparative Example 1 indicates that a fluorine-tungsten titanium oxide solid solution was obtained. In Example 3, the simultaneous presence of fluorine, tungsten, and niobium indicates that fluorine, tungsten, and niobium elements were successfully incorporated into anatase TiO2.

[0088] Figure 3 The concentrations of tungsten and niobium in Example 3 at different etching depths are shown. As the etching depth increases from 0 to 4 nm, the W concentration gradually increases from 12.7% to 28.4%, while the Nb concentration decreases from 21% to 11%. This indicates that the W dopant is mainly located inside the nanocrystalline titanium dioxide, while the Nb dopant is located in the surface shell of the nanocrystals. Therefore, this result confirms the successful combination of fluorotungsten titanium dioxide and fluoroniobium titanium dioxide, as well as the successful integration of the core / shell structure.

[0089] Figure 4(a) shows the UV-Vis-NIR absorption spectra of Example 1 in four different nonpolar solvents: n-hexane, tetrachloroethylene, carbon tetrachloride, and carbon disulfide. Figure 4(b) shows the relationship between the LSPR absorption peaks of Example 1 in different solvents and the dielectric constant of the solvents in Figure 4(a). Based on the sensitivity of the LSPR effect to the external dielectric environment, and the fact that the absorption peak position shifts depending on the medium, researchers often determine the occurrence of LSPR based on the peak position shift. Since carbon tetrachloride and n-hexane exhibit baseline-inelastic solvent absorption in the 1650nm-1780nm and 2050-2500nm ranges, Example 1, with the shortest absorption peak position, was selected. Figure 4(a) shows that when the sample of Example 1 was dispersed in n-hexane, carbon tetrachloride, tetrachloroethylene, and carbon disulfide, peaks appeared at 1230nm, 1265nm, 1290nm, and 1330nm, respectively, with a certain degree of redshift. Figure 4(b) shows the relationship between the LSPR absorption peaks of Example 1 in different solvents and the dielectric constant of the solvent in Figure 4(a). The figure shows that the dielectric constant of n-hexane is the smallest. When the sample of Example 1 is dispersed in n-hexane, the LSPR peak appears at 1230 nm. As the dielectric constant of the solvent gradually increases, the position of the peak changes to 1265 nm, 1290 nm and 1330 nm respectively. The peak position gradually increases, indicating that the position of the absorption peak of the sample of Example 1 in different solvents has a positive linear relationship with the refractive index of the solvent. This is consistent with the sensitivity of LSPR to the dielectric constant of the environment, thus proving that the absorption in the sample is the LSPR effect caused by doping.

[0090] Figure 5(a) shows the UV-Vis and near-infrared absorption spectra of the products obtained in Comparative Example 1, Example 1, Example 2, Example 3, Example 4, and Example 5. Figure 5(b) is a smoothed magnified view of the peak positions of the curve in Figure 5(a). The figure shows that Comparative Example 1 has a peak at around 1185 nm with an absorbance range of 0.4-0.5. Compared to Comparative Example 1, the absorbance of the peaks in Examples 1, 2, 3, 4, and 5 gradually increases to 0.5-0.65. Figure b is a smoothed magnified version of Figure a, showing that the peak of the Comparative Example is at 1185 nm. By changing the core-shell ratio, i.e., gradually increasing it from 1:1 in Example 1 to 1:5 in Example 5 (1:5), the LSPR of the samples can achieve a wide redshift of the absorption peak from 1185 nm to 1725 nm. The near-infrared absorption region also continuously widens, indicating that the core-shell structure can achieve a wide range of peak position control from 185 nm to 1725 nm by changing the core-shell molar ratio. The stronger peak absorbance and the wider absorption region indicate a more significant infrared absorption effect.

[0091] Figure 6The solar transmittance spectra of AM 1.5G solar spectrum and the products obtained in Comparative Example 1 and Example 3 are shown. The near-infrared blocking efficiencies of Comparative Example 1 and Example 3 are 61% and 74.3%, respectively, indicating that the near-infrared shielding efficiency of the core-shell structured titanium dioxide solid solution film is improved.

[0092] Figure 7 The thermal insulation diagrams of the films prepared from the products obtained in Comparative Example 1 and Example 3 show that the thermal insulation temperature of the films prepared from the products obtained in Example 1 and Example 3 was reduced by 19 and 24.3°C, respectively, compared to the films without the addition of this product. This indicates that Example 3 can achieve a better indoor cooling effect.

[0093] Localized surface plasmon resonance (LSPR) is a phenomenon caused by coherent electron oscillations. The occurrence of LSPR resonance leads to several effects. Firstly, when the resonance effect occurs, particles strongly absorb light energy and convert it into their own energy. Given the increasingly serious energy consumption problem, with buildings accounting for approximately 30% to 40% of total human energy consumption, about half of which is caused by air conditioning (heating or cooling), LSPR absorption of light energy can be an important way to reduce building energy consumption. The absorbed energy can also be used in medical fields such as photocatalysis and photothermal therapy. Secondly, LSPR causes a significant enhancement of the local electromagnetic field around the particles. This near-field enhancement characteristic is widely used in near-field signal amplification, such as in biological fluorescence imaging and SERS.

[0094] This invention discovers that by combining fluorinated niobium titanium oxide solid solutions and fluorinated tungsten titanium oxide solid solutions, which have absorption in the mid-infrared and near-infrared regions respectively, and forming a core-shell structure through a hot-injection method, a nano-titanium oxide with stronger absorption in the near-infrared region is obtained due to the superposition of the properties of the two materials and the regulation of carrier concentration by the core-shell structure. Compared with the fluorinated tungsten titanium oxide solid solution prepared by the prior art, the absorbance of the peak position of the core-shell titanium oxide solid solution in the near-infrared region gradually increases from 0.5 to 0.8, effectively improving the near-infrared absorption performance of the material. Utilizing the strong absorption characteristic of this material in the near-infrared region, a transparent heat-insulating coating can be prepared for use in the field of building energy conservation. This invention presents a core-shell structured titanium dioxide solid solution material with both strong absorption and wide-range tunable LSPR effect. This material can achieve a wide-range tunable LSPR effect of 1185nm-1725nm in the near-infrared II region. Compared with Au and Ag, this material has a significant price advantage and peak position control advantage. It can replace the expensive and difficult-to-control Au and Ag materials, becoming a new material for NIR-II nanoprobes, improving the penetration depth, resolution, and signal-to-noise ratio of in vivo imaging, broadening the imaging range, and improving imaging quality.

[0095] The above embodiments are not intended to limit the technical solutions of the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solutions of the present invention.

Claims

1. A core-shell structured titanium dioxide solid solution material exhibiting both strong absorption and a wide-range tunable LSPR effect, characterized in that: A core-shell structure is constructed with fluorotungsten titanium oxide solid solution nanoparticles as the core and fluoroniobium titanium oxide solid solution as the shell. The fluorotungsten titanium oxide solid solution is synthesized by ammonolysis after degassing the core precursor and tungsten source. The core-shell structure is prepared by injecting the shell precursor and niobium source into the fluorotungsten titanium oxide solid solution, degassing, and reacting at 280℃-330℃ to synthesize the outer shell fluoroniobium titanium oxide solid solution, which then coats the surface of the fluorotungsten titanium oxide solid solution core nanoparticles. The mixture is then cooled to room temperature, centrifuged, washed, and dried. The raw materials for the core or shell precursor consist of an alcohol source, a reaction solvent, a morphology control agent, a titanium source, and a fluorine source.

2. The core-shell structured titanium dioxide solid solution material with both strong absorption and wide-range tunable LSPR effect as described in claim 1, characterized in that: The alcohol source is one or more of octadecyl alcohol, hexadecyl alcohol, and dodecanol; the morphology control agent is one or more of oleic acid and oleylamine; and the reaction solvent is one or more of octadecene and tetradecene.

3. The core-shell structured titanium dioxide solid solution material with both strong absorption and wide-range tunable LSPR effect as described in claim 1, characterized in that: The titanium source is one or more of tetraethyl titanate, isopropyl titanate, titanium tetrachloride, and titanium n-butoxide; the tungsten source is one or more of tungsten hexachloride, tungsten pentachloride, ammonium tungstate, and sodium tungstate; the niobium source is niobium pentachloride; and the fluorine source is one or more of sodium fluoride, potassium fluoride, ammonium fluoride, and hydrofluoric acid.

4. The core-shell structured titanium dioxide solid solution material with both strong absorption and wide-range tunable LSPR effect as described in claim 1, characterized in that: The molar ratio of alcohol source: fluorine source: titanium source is (150-300):(2-10):20; the volume ratio of morphology control agent, reaction solvent and titanium source is (2-15):(20-200):

1.

5. The core-shell structured titanium dioxide solid solution material with both strong absorption and wide-range tunable LSPR effect according to claim 1, characterized in that: The molar ratio of the tungsten source to the titanium source is (1-4):

10.

6. The core-shell structured titanium dioxide solid solution material with both strong absorption and wide-range tunable LSPR effect according to claim 1, characterized in that... The molar ratio of niobium source to titanium source is (1-5):

10.

7. The core-shell structured titanium dioxide solid solution material with both strong absorption and wide-range tunable LSPR effect according to claim 1, characterized in that: The molar ratio of tungsten source to niobium source is (1-1):(1-5).

8. The core-shell structured titanium dioxide solid solution material with both strong absorption and wide-range tunable LSPR effect according to claim 1, characterized in that: The ammonolysis reaction refers to heating to 280℃-300℃ under a nitrogen atmosphere and reacting for 60-90 minutes; the reaction time at 280℃-330℃ is 60-90 minutes; the degassing in the degassing of the nuclear precursor and tungsten source, or the degassing in the reaction at 280℃-330℃ after degassing, is carried out in a vacuum at 100℃-140℃ for 20-40 minutes; The cooling described is natural cooling to room temperature; The centrifugal washing process involves dissolving the product in hexane after cooling to room temperature, then precipitating the dissolved product again with acetone and ethanol, wherein the volume ratio of hexane, acetone and ethanol is (1-2):5:

4. The product is then heated to 50-60°C and held for 5-15 minutes, and centrifuged at 5000-12000 r / min. This process is repeated 4-6 times. The drying process involves drying in a vacuum drying chamber at 60-80℃ for 12-24 hours.

9. A method for preparing a core-shell structured titanium dioxide solid solution material with both strong absorption and wide-range tunable LSPR effect as described in any one of claims 1-8, characterized in that... Includes the following steps: 1) Fluorotungsten titanium oxide solid solution nanoparticles were synthesized by degassing the nuclear precursor and tungsten source and then reacting them with ammonolysis. 2) The shell precursor and niobium source were injected into the fluorotungsten titanium oxide solid solution. After degassing, the outer shell fluoroniobium titanium oxide solid solution was synthesized at 280℃-330℃ and coated on the surface of the core nanoparticles to form a core-shell structure with fluorotungsten titanium oxide solid solution as the core and fluoroniobium titanium oxide solid solution as the shell. 3) Cool the core-shell structure to room temperature, centrifuge, wash, and dry to obtain a core-shell titanium dioxide solid solution material with both strong absorption and wide-range tunable LSPR effect.

10. The application of the core-shell structured titanium dioxide solid solution material with strong absorption and wide-range tunable LSPR effect as described in any one of claims 1-8 in the preparation of transparent heat-insulating coatings and in the preparation of NIR-II nanoprobes as a substitute for Au and Ag.

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