Ti-doped CsWO nanocrystal material for automobile heat insulation and ultraviolet protection and preparation method of Ti-doped CsWO nanocrystal material

Abstract

The invention discloses a preparation method of a Ti-doped CsWO nanocrystal material for automobile heat insulation and ultraviolet protection, all Ti-doped CsWO nanocrystal systems are successfully prepared through a solid phase method, the Ti doping concentration of 1.354 at.% is innovatively introduced, and breakthrough improvement of the material performance is achieved. According to the technical scheme, a crystal structure is regulated and controlled through Ti doping, the carrier concentration is promoted to be increased to 3.2 * 10 cm < 3 >, meanwhile, oxygen vacancy formation and W < 5 + > proportion are induced to be increased to 18.6%, and the local surface plasmon resonance effect is effectively enhanced. Through testing, the transmittance of the optimized material in the visible light wave band of 380-780 nm reaches 86%, the near-infrared shielding rate exceeds 93%, the ultraviolet blocking efficiency reaches 99.2%, and the comprehensive optical performance of the material is improved by 35% compared with that of an undoped sample. The film is particularly suitable for the field of automobile glass film pasting, and active heat radiation shielding can be achieved while high light transmittance is guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of automotive intelligent thermal management materials technology, and specifically relates to a Ti-doped CsWO nanocrystal material for automotive heat insulation and ultraviolet protection and its preparation method. Background Technology

[0002] Research on the background of automotive intelligent thermal management materials technology shows that traditional thermal management materials face significant technical bottlenecks in addressing the energy efficiency challenges of new energy vehicles. Existing thermal insulation materials all have different defects: metal oxide coatings (72%-78% visible light transmittance) cause performance degradation of vehicle communication systems due to electromagnetic shielding effects; the brittle fracture problem of ITO nanocoatings results in a less than 65% compatibility rate with curved glass; and VO2 phase change films exhibit a 14.7% degradation in infrared modulation performance under extreme temperature cycling.

[0003] Therefore, there is an urgent need to provide a novel Ti-doped CsWO nanocrystal material for automotive heat insulation and ultraviolet protection, as well as its preparation method, to solve the above problems. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a Ti-doped CsWO nanocrystal material for automotive heat insulation and ultraviolet protection, and its preparation method, which can achieve active thermal radiation shielding while ensuring high light transmittance.

[0005] To solve the above-mentioned technical problems, the first technical solution adopted by the present invention is: to provide a method for preparing Ti-doped CsWO nanocrystalline materials for automotive heat insulation and ultraviolet protection, comprising the following steps: Step S1: Preparation of Cs x Ti y W 1-y O3 powder, where x is 0.3-0.33 and y is 0-0.03, includes the following steps: S101: Add tetrabutyl titanate to HCl and stir until a colorless and transparent Ti ion precursor solution is formed; S102: Add Ti ion precursor solution and hydrogen peroxide to tungstic acid in sequence, and stir at 45℃-55℃ until the reaction is complete; S103: Add cesium chloride to the solution prepared in step S102 by molar ratio Cs / W = 0.3-0.33, stir and then dry; S104: The dried sample is reduced under a reducing gas until the temperature drops to room temperature to obtain titanium-doped cesium tungsten bronze powder. Step S2: Preparation of Cs x Ti y W 1-y O3 thin film, including the following steps: S201: Restore the Cs x Ti y W 1-y O3 powder was mixed with ethanol and then ball-milled to obtain Cs. x Ti y W 1-y O3 solution; S202: Cs x Ti y W 1-y O3 solution and silica sol are mixed at a mass ratio of (0.8-1.5):5, and then coated on glass after thorough mixing.

[0006] In a preferred embodiment of the present invention, in step S104, the reducing gas is H2 with a N2 content of 5%-25%, and the reduction treatment conditions are 500℃ / 1h-650℃ / 1h.

[0007] In a preferred embodiment of the present invention, in step S202, the silica sol is prepared by a hydrothermal method using a mixture of tetraethyl orthosilicate, hydrochloric acid and methanol.

[0008] To solve the above-mentioned technical problems, the second technical solution adopted by the present invention is: to provide a Ti-doped CsWO nanocrystal material prepared by the preparation method of Ti-doped CsWO nanocrystal material for automotive heat insulation and ultraviolet protection as described in any of the above claims.

[0009] To solve the above-mentioned technical problems, the second technical solution adopted by the present invention is to provide an application of Ti-doped CsWO nanocrystal material as described in any of the above claims in automotive heat insulation and ultraviolet protection.

[0010] In a preferred embodiment of the present invention, under the condition that Ti / (Ti+W) is 3%, the prepared film has a visible light transmittance T of 86.55%. vis The near-infrared shielding efficiency S NIR It reached 93.68%.

[0011] The beneficial effects of this invention are: (1) This invention successfully prepared a Ti-doped CsWO nanocrystal system via a solid-state method, innovatively introducing a Ti doping concentration of 1.354 at.% to achieve a breakthrough improvement in material properties. This technical solution regulates the crystal structure through Ti doping, thereby increasing the carrier concentration to 3.2 × 10 cm⁻¹. 3 Simultaneously induces oxygen vacancy formation and W 5+ The proportion increased to 18.6%, effectively enhancing the local surface plasmon resonance (LSPR) effect; (2) The Ti-doped CsWO3 composite structure innovatively developed in this invention achieves synergistic optimization of 86.55% visible light transmittance and 93.68% infrared blocking rate through a dual plasmon resonance mechanism (LSPR band 1100-2500nm, small polaron absorption 780-1100nm). (3) According to the test, the optimized material has a transmittance of 86% in the visible light band of 380-780nm, a shielding rate of more than 93% in the near infrared (780-2500nm) band, and an ultraviolet blocking efficiency of 99.2%. Its comprehensive optical performance is 35% higher than that of the undoped sample. (4) This invention is particularly applicable to the field of automotive glass film, which can achieve active heat radiation shielding while ensuring high light transmittance, reduce the use of automotive air conditioning, and has anti-aging properties.

[0012] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 Scanning electron microscope images of four samples, CT-0, CT-3, CT-7 and CT-10, from embodiments of the present invention are shown. Figure 2 A schematic diagram illustrating the near-infrared shielding mechanism of the cesium tungsten bronze is shown. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Please see Figure 1 and Figure 2 The embodiments of the present invention include: A method for preparing Ti-doped CsWO nanocrystal materials for automotive heat insulation and ultraviolet protection includes the following steps: Step S1: Preparation of Cs x Ti y W 1-y O3 powder, i.e., for preparing Ti-doped Cs x WO3 precursor powder. Includes the following steps: S101: Add 4M tetrabutyl titanate to 2M HCl and stir until a colorless and transparent Ti ion precursor solution is formed. S102: Add the Ti ion precursor solution and 44 ml of hydrogen peroxide to 0.05 mol of tungstic acid in sequence, and stir at 50 °C until the reaction is complete; S103: Cesium chloride was added to the solution prepared in step S102 at a molar ratio of Cs / W=0.33, stirred for 3 hours, and then dried at 120°C. S104: The dried sample was subjected to reduction treatment at 600℃ for 1h under reducing gas (H2 / N2=20 / 180) until the temperature dropped to room temperature to obtain titanium-doped cesium tungsten bronze powder. Cs with Ti / (Ti+W)(mol) = 0, 0.03, 0.07 and 0.1 were synthesized using the above method. x Ti y W 1-y O3 powders were named CT-0, CT-3, CT-7 and CT-10, respectively. The preparation methods of each powder were the same, except that the solution content of the added Ti ion precursor was different. The corresponding solution contents of the added Ti ion precursor were 0g, 3g, 5g and 10g, respectively.

[0017] Step S2: Preparation of Cs x Ti y W 1-y O3 thin film, including the following steps: S201: Restore the Cs x Ti y W 1-y O3 powder was mixed with ethanol and ball-milled for 7 hours to obtain well-dispersed Cs. x Ti y W 1-y O3 solution; S202: Cs x Ti y W 1-y O3 solution and self-made silica sol were mixed at a mass ratio of 0.9:5, and after thorough mixing, a film was applied to glass. The silica sol was prepared by a hydrothermal method using a mixture of tetraethyl orthosilicate, hydrochloric acid, and methanol.

[0018] This invention uses W 6+ Ti with similar ionic radii 4+ Cs was successfully synthesized by substituting W ions for W ions. x Ti y W 1- y O3 material. Furthermore, a solid-state method was selected as the preparation process to shorten the preparation cycle and obtain reproducible samples.

[0019] This invention incorporates the intrinsic mechanism of tungsten bronze and systematically studies the effects of different Ti ion doping amounts on the valence state distribution, elemental content, surface morphology, and optical properties of W in the material.

[0020] Figure 1 Scanning electron microscope (SEM) images of four samples are presented. Figure 1 Figure a shows the CT-0 sample, composed of particles and nanoplates with an average size of 50 nm. Samples CT-3 and CT-7 ( Figure 1 b and Figure 1 c) It consists of particles of 20-100 nm and nanobulks of several hundred nanometers, but the CT-3 sample also contains a small amount of nanoplatelets. Sample CT-10 is composed of nanoparticles of approximately 70 nm, such as... Figure 1 As shown in d, the number of nanoplatelets gradually decreases with increasing Ti concentration, which is consistent with the XRD results. Increased Ti concentration inhibits the growth of the (200) crystal plane, while a small amount of Ti can promote the formation of nanobulks, as evidenced by the greater number of nanobulks in the CT-7 sample compared to the CT-3 sample. However, excessive Ti doping produces more TiO2, which surrounds the cesium tungsten bronze, thereby inhibiting its growth and resulting in smaller particles.

[0021] Table 1 Valence ratio, elemental content, and elemental ratio of W in different Ti-doped samples

[0022] Figure 2 The near-infrared shielding mechanism of cesium tungsten bronze was demonstrated, which is mainly achieved through small polaron absorption and localized surface plasmon resonance (LSPR). Figure 2 (a) is the structural framework of CsxTiyW1-yO3 projected onto the ab plane; Figure 2 (b) is a schematic diagram of the growth of four samples (CT-0, CT-3, CT-7 and CT-10); Figure 2 (c) is a schematic diagram of the LSPR effect; Figure 2 (d) is a schematic diagram of small polaron absorption. Small polaron absorption mainly acts in the short-wavelength near-infrared region (780-1100 nm). Small polarons caused by lattice distortion in W 5+ and W6+ The polaron transitions absorb near-infrared light and are as follows: Process І:

[0023] Ephonon represents the energy of a single phonon.

[0024] The LSPR effect mainly acts on the long-wavelength near-infrared region. In the LSPR effect, when free electrons are in a resonant state, they absorb near-infrared light with a frequency close to their vibration frequency. The near-infrared absorption capability of LSPR is closely related to the carrier concentration (specifically the free electron concentration), as shown in formula (2); (2) Where α, λ, N, ɛ0, m*, n, and µ represent the absorption coefficient, incident light wavelength, refractive index of the medium, vacuum permittivity, effective carrier mass, carrier concentration, and permeability, respectively; under the same conditions, the values ​​of N, ɛ0, m*, and µ are fixed. The absorption coefficient is related to the incident wavelength λ. 2 The coefficient is proportional to the carrier concentration n, indicating that increasing the carrier concentration can improve the near-infrared absorption coefficient of the material.

[0025] As the Ti concentration increases, CT-7 and CT-10 samples exhibit better absorption performance in the ultraviolet region. This change can be explained by band gap theory. Therefore, the band gap information of the samples is calculated using formula (3). (3) In the formula, α, ν, h、 Eg and B represent the absorption coefficient, photon energy, Planck's constant, band gap width, and constant, respectively. Table 2 shows the band gaps of the four samples as 2.71 eV, 3.08 eV, 2.91 eV, and 2.89 eV. The sample bandwidth first increases and then decreases with increasing Ti doping content, consistent with the changes in the UV absorption spectrum. This indicates that the increase in band gap leads to a shift of the UV absorption peak towards shorter wavelengths.

[0026] Table 2 shows the optical properties of the samples in automotive glass. With increasing Ti concentration, the near-infrared shielding efficiency increased from 88.43% for CT-0 to 93.68% for CT-3, while the visible light transmittance reached 86.55%. However, with increasing Ti content, the near-infrared shielding efficiency of samples CT-7 and CT-10 decreased to 88% and 83%, respectively. Although these two samples showed reduced near-infrared shielding effectiveness, they exhibited good performance in ultraviolet absorption.

[0027] Table 2 Optical properties and band gaps of different Ti dopants

[0028] In the table, a It represents the maximum transmittance in the visible light region (380-760 nm). b This indicates the maximum shielding efficiency in the NIR region (760-2500 nm).

[0029] To quantitatively compare the near-infrared shielding capabilities of the four samples, the Solar Energy Transmittance Selectivity (SETS) value was calculated based on the solar transmittance deviation in the visible and near-infrared regions. The SETS value can be calculated using the following formula (4); (4) In the formula, T(λ) represents the transmission spectrum, and E(λ) represents the solar radiation spectrum of 1.5 air masses, corresponding to the sun at 37° above the horizon. SETS values ​​range from 0 to 1; higher SETS values ​​indicate better transmission selectivity, while lower SETS values ​​indicate poorer transmission selectivity. As shown in Table 2, among the four samples prepared by the solid-state method, the SETS value of the CT-3 sample (0.79) is higher than the other samples, indicating that appropriate Ti doping to replace W can improve the optical properties of CsxWO3 material.

[0030] Experimental results show that, under the condition of Ti / (Ti+W) = 3%, the prepared film has excellent visible light transmittance (T). vis The shielding efficiency reached 86.55%, while the near-infrared shielding efficiency (S) was... NIR The rate was as high as 93.68%.

[0031] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing Ti-doped CsWO4 nanocrystal material for automotive heat insulation and ultraviolet protection, characterized in that, The method comprises the following steps: Step S1: Preparation of Cs x Ti y W 1-y O3 powder, wherein x is 0.3-0.33, y is 0-0.03, comprising the following steps: S101: stirring tetrabutyl titanate into HCl until a colorless transparent Ti ion precursor solution is formed; S102: adding the Ti ion precursor solution and hydrogen peroxide into tungstic acid in sequence and stirring at 45-55°C until the reaction is completed; S103: adding cesium chloride into the solution prepared in step S102 at a molar ratio of Cs / W=0.3-0.33, stirring and then drying; S104: reducing the dried sample under a reducing gas, and obtaining a titanium-doped cesium tungsten bronze powder when the temperature drops to room temperature; Step S2: Preparation of Cs x Ti y W 1-y O3 film, comprising the steps of: S201: reduce the Cs x Ti y W 1-y O3 powder is mixed with ethanol and ball milled to obtain Cs x Ti y W 1-y O3 solution; S202: Cs x Ti y W 1-y The O3 solution and the silica sol were mixed in a mass ratio of (0.8-1.5):5, and after uniform mixing, a film was coated on the glass.

2. The method for preparing Ti-doped CsWO4 nanocrystalline material for thermal and ultraviolet shielding of automobiles according to claim 1, characterized in that, In step S104, the reducing gas is H2 with a N2 content of 5-25%, and the reducing treatment is performed at 500-650°C for 1h.

3. The method for preparing Ti-doped CsWO4 nanocrystalline material for heat insulation and ultraviolet protection of automobiles according to claim 1, characterized in that, In step S202, the silica sol is prepared by hydrothermal method using tetraethyl orthosilicate, hydrochloric acid and methanol.

4. A Ti-doped CsWO nanocrystalline material prepared by the method for preparing a Ti-doped CsWO nanocrystalline material for automobile heat insulation and ultraviolet protection according to any one of claims 1 to 3.

5. The Ti-doped CsWO nanocrystalline material according to claim 4 in the application of automobile heat insulation and ultraviolet protection.

6. Use according to claim 5, wherein The prepared thin film has a visible light transmittance T of 86.55% under the condition that Ti / (Ti+W) is 3% vis , and a near-infrared shielding efficiency S NIR reaches 93.68%.

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