Rutile TiO 2 Nanorods / F-doped anatase TiO 2 Nanosheet composite material and preparation method and application thereof

Abstract

The present invention relates to the technical field of electrochromic thin film materials, and provides a rutile-phase TiO2 nanorod / fluorine-doped anatase-phase TiO2 nanosheet composite material, a preparation method and an application thereof. The composite material of the present invention is composed of an FTO conductive glass substrate and rutile-phase TiO2 nanorods and fluorine-doped anatase-phase TiO2 nanosheets that are sequentially grown on one side of the FTO conductive glass substrate. It is prepared by hydrothermal method to induce the growth of one-dimensional single-crystal rutile-phase TiO2 nanorods on the surface of a pretreated FTO conductive glass substrate in precursor solution A, and then the solvothermal method is used to induce the in-situ epitaxial growth of anatase-phase TiO2 nanosheets on the one-dimensional single-crystal rutile-phase TiO2 nanorods in precursor solution B, and the surface of the anatase-phase TiO2 nanosheets is fluorinated with a NaF solution. The present invention can improve the cycle stability of the composite material and the electron transfer efficiency between the conductive substrate and the TiO2 nanosheets, and achieve independent and selective optical transmittance modulation of visible light and near-infrared light.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochromic thin film materials, and particularly relates to a rutile phase TiO 2 nanorod / fluorine-doped anatase phase TiO 2 nanosheet composite material, a preparation method thereof, and an application thereof. Background Art

[0002] Electrochromic devices can optimize the utilization of solar energy by adjusting the light transmittance and absorption rate, improve the comfort of life, and reduce energy consumption, thus becoming one of the research hotspots in the field of building energy conservation. As is well known, the solar radiation reaching the earth's surface contains almost equal proportions of visible light and infrared radiation in addition to ultraviolet light. Visible light can achieve indoor space lighting, while infrared radiation generates a thermal effect. Ideally, if independent control of solar heat radiation and daylighting can be achieved through smart windows, it is expected to have a significant impact on the energy efficiency of buildings and the comfort of occupants. Currently, many electrochromic materials can only transmit or block visible light and near-infrared rays simultaneously under a specific applied voltage, without spectral selectivity. Therefore, how to construct an electrochromic material with dual-band independent modulation ability is a very urgent task.

[0003] TiO 2 Due to its excellent thermal stability, weather resistance, non-toxicity and other characteristics, it is widely regarded as a promising electrochromic candidate material. In order to obtain the required dual-band modulation ability, TiO 2 is usually doped with hetero-valent metal atoms such as Nb and Ta to induce an increase in its free electron density and an improvement in near-infrared selective modulation ability. The introduction of Nb element can induce the improvement of the dual-band modulation ability of TiO 2 nanosheets. However, Nb doping will simultaneously introduce lattice strain and lattice distortion. When ions are embedded / extracted in the TiO 2 lattice, structural distortion and lattice collapse are likely to occur, which has an adverse effect on the structural stability of the matrix and the ion diffusion in the matrix lattice, resulting in its cycle stability not reaching the ideal durability. After 500 cycles, the dual-band selective modulation ability is almost lost, which seriously hinders its development and application in the electrochromic field (see "Niobium and Fluorine Dually-Doped Titanium Oxide Nanosheet Arrays for Selective Dual-Band Electrochromic Applications" published in Volume 6, Issue 12 of "ACS Applied Nano Materials", and the article DOI number is 10.1021 / acsanm.3c01160).

[0004] Cycling stability is an important indicator for evaluating the comprehensive performance of electrochromic devices and cannot be ignored. Since there is a contradiction between it and other performance indicators such as optical contrast and response time, how to introduce defects through doping to improve the dual-band selective modulation ability while constructing TiO with high contrast, fast response time and excellent cyclic stability 2 Based electrochromic materials have become a technical problem that needs to be solved urgently. SUMMARY OF THE INVENTION

[0005] In view of this, in order to overcome the shortcomings of the prior art, the present invention provides a rutile phase TiO 2 Nanorods / Fluorine-doped anatase TiO 2 Nanosheet composite materials and their preparation methods and applications.

[0006] According to a first aspect of the present invention, the present invention provides a rutile phase TiO 2 Nanorods / Fluorine-doped anatase TiO 2 Nanosheet composite material, the rutile phase TiO 2 Nanorods / Fluorine-doped anatase TiO 2 The nanosheet composite material is composed of a FTO conductive glass substrate and a rutile phase TiO2 grown on one side of the FTO conductive glass substrate. 2 Nanorods and fluorine-doped anatase TiO 2 Nanosheets, the rutile phase TiO 2 Nanorods / Fluorine-doped anatase TiO 2 The nanosheet composite material is prepared by inducing a one-dimensional single crystal rutile phase TiO in the precursor solution A by a hydrothermal method 2 The nanorods were grown on the surface of the pretreated FTO conductive glass substrate, and then the anatase phase TiO was induced in the precursor solution B by solvothermal method 2 Nanosheets in one-dimensional single crystal rutile phase TiO 2 In-situ epitaxial growth of nanorods and the use of NaF solution to precipitate anatase TiO 2 The nanosheets were prepared by surface fluorination treatment, wherein the precursor solution A was prepared by 2-3 mL tetrabutyl titanate, 10-15 mL concentrated hydrochloric acid and 15 ml deionized water, and the precursor solution B was prepared by 160-320 μL tetrabutyl titanate, 5-15 mL triethanolamine, 160-320 μL hydrofluoric acid and 15 mL n-butanol. The concentration of the NaF solution used for surface treatment was 0.5x10 -2 -1x10 -2 mol / L.

[0007] Preferably, the rutile phase TiO 2 ​​​​Nanorod / Fluorine-doped Anatase TiO 2 nanosheet composite material, which is prepared according to the following steps:

[0008] Step 1. Pretreatment of FTO conductive glass substrate

[0009] Place the FTO conductive glass substrate in acetone, ethanol, and deionized water in sequence, perform ultrasonic cleaning for 15 minutes respectively, and then dry it with nitrogen to obtain the pretreated FTO conductive glass substrate;

[0010] Step 2. Preparation of precursor solution A

[0011] Add tetrabutyl titanate and 12 mol / L concentrated hydrochloric acid to deionized water according to the ratio. Among them, the volumes of tetrabutyl titanate, concentrated hydrochloric acid, and deionized water are 2 - 3 mL, 10 - 15 mL, and 15 mL respectively. After stirring, obtain precursor solution A;

[0012] Step 3. Preparation of rutile TiO 2 nanorods

[0013] Fix the conductive surface of the pretreated FTO conductive glass substrate obtained in Step 1 downward at 45° in the precursor solution A prepared in Step 2 for hydrothermal reaction. The hydrothermal reaction temperature is 140 - 150 °C, and the hydrothermal reaction time is 3 - 4 h. After naturally cooling to room temperature, rinse with deionized water and dry in air at 80 °C for 12 h. Finally, anneal in air at 450 °C for 0.5 - 1 h to obtain rutile TiO 2 nanorods on the FTO conductive glass substrate;

[0014] Step 4. Preparation of precursor solution B

[0015] Add tetrabutyl titanate, triethanolamine, and hydrofluoric acid to n-butanol according to the ratio. Among them, the contents of tetrabutyl titanate, triethanolamine, hydrofluoric acid, and n-butanol are 160 - 320 μL, 5 - 15 mL, 160 - 320 μL, and 15 mL respectively. After stirring, obtain precursor solution B;

[0016] Step 5. Preparation of anatase TiO 2 nanosheets

[0017] Fix the conductive surface of the FTO conductive glass substrate with rutile TiO 2 nanorods prepared in Step 3 downward at 45° in the precursor solution B prepared in Step 4. After mixing, place it in a reaction kettle and carry out solvothermal reaction under nitrogen protection. The solvothermal reaction temperature is 150 - 200 °C, and the solvothermal reaction time is 12 - 20 h. After naturally cooling to room temperature, rinse with deionized water and dry at a temperature of 80 - 100 °C for 12 - 16 h. In the rutile TiO-containing2 Anatase TiO was prepared on the FTO conductive glass substrate of the nanorods 2 nanosheets;

[0018] Step Six, surface fluorination treatment

[0019] The anatase TiO prepared in Step Five 2 nanosheets were immersed in a NaF solution with a concentration of 0.5x10 -2 -1x10 -2 mol / L for 10 - 12 h, then rinsed with deionized water, air-dried naturally, and annealed in air at 300 - 400 °C for 0.5 - 1 h to obtain rutile TiO 2 nanorods / fluorine-doped anatase TiO 2 nanosheet composite material.

[0020] Preferably, the rutile TiO of the present invention 2 nanorods / fluorine-doped anatase TiO 2 nanosheet composite material can achieve independent and selective optical transmittance modulation of visible light and near-infrared light under a voltage of +1.5 V to -1.5 V.

[0021] Preferably, the rutile TiO of the present invention 2 nanorods / fluorine-doped anatase TiO 2 nanosheet composite material has a contrast ratio of 57.2 - 70% at a wavelength of 700 nm, a contrast ratio of 50.3 - 63.8% at a wavelength of 1300 nm, a coloring time of 22.1 - 31.1 s at a wavelength of 700 nm, and a fading time of 8.0 - 9.3 s.

[0022] Preferably, the rutile TiO of the present invention 2 nanorods / fluorine-doped anatase TiO 2 nanosheet composite material can provide three different sunlight adjustment modes, namely a bright mode that supports the transmission of visible light and near-infrared light, a cool mode that blocks near-infrared light and supports the transmission of visible light, and a dark mode that isolates the transmittance of near-infrared light and visible light.

[0023] Preferably, the rutile TiO of the present invention 2 nanorods / fluorine-doped anatase TiO 2 nanosheet composite material has an unchanged optical modulation amplitude at a wavelength of 700 nm after 2000 coloring and fading cycles, and the optical modulation amplitude at a wavelength of 1300 nm decreases by 16.7%.

[0024] According to the second aspect of the present invention, the present invention also relates to the above rutile TiO 2Nanorod / Fluorine-doped Anatase TiO 2 Application of nanosheet composite material as electrochromic smart window.

[0025] According to the third aspect of the present invention, the present invention provides a rutile TiO 2 Nanorod / Fluorine-doped Anatase TiO 2 Preparation method of nanosheet composite material, including:

[0026] Step 1: Pretreatment of FTO conductive glass substrate

[0027] Place the FTO conductive glass substrate in acetone, ethanol, and deionized water in sequence, perform ultrasonic cleaning for 15 minutes respectively, and then dry it with nitrogen to obtain the pretreated FTO conductive glass substrate;

[0028] Step 2: Preparation of precursor solution A

[0029] Add tetrabutyl titanate and 12 mol / L concentrated hydrochloric acid to deionized water according to the ratio. Among them, the volumes of tetrabutyl titanate, concentrated hydrochloric acid, and deionized water are 2 - 3 mL, 10 - 15 mL, and 15 mL respectively. After stirring, obtain precursor solution A;

[0030] Step 3: Preparation of rutile TiO 2 Nanorods

[0031] Fix the conductive surface of the pretreated FTO conductive glass substrate in step 1 downward at 45° in the precursor solution A prepared in step 2 for hydrothermal reaction. The hydrothermal reaction temperature is 140 - 150 °C, and the hydrothermal reaction time is 3 - 4 h. After natural cooling to room temperature, rinse with deionized water and dry in air at 80 °C for 12 h. Finally, anneal in air at 450 °C for 0.5 - 1 h to obtain rutile TiO 2 Nanorods;

[0032] Step 4: Preparation of precursor solution B

[0033] Add tetrabutyl titanate, triethanolamine, and hydrofluoric acid to n-butanol according to the ratio. Among them, the contents of tetrabutyl titanate, triethanolamine, hydrofluoric acid, and n-butanol are 160 - 320 μL, 5 - 15 mL, 160 - 320 μL, and 15 mL respectively. After stirring, obtain precursor solution B;

[0034] Step 5: Preparation of anatase TiO 2 Nanosheets

[0035] The rutile TiO prepared in step 3 2The conductive surface of the FTO conductive glass substrate with nanorods is fixed downward at 45° in the precursor solution B prepared in Step Four. After mixing, it is placed in a reaction kettle and subjected to a solvothermal reaction under nitrogen protection. The solvothermal reaction temperature is 150 - 200 °C, and the solvothermal reaction time is 12 - 20 h. After natural cooling to room temperature, it is rinsed with deionized water and dried at a temperature of 80 - 100 °C for 12 - 16 h. Anatase TiO 2 nanosheets are prepared on the FTO conductive glass substrate with nanorods; 2

[0036] Step Six: Surface fluorination treatment

[0037] The anatase TiO 2 nanosheets prepared in Step Five are soaked in a NaF solution with a concentration of 0.5x10 -2 -1x10 -2 mol / L for 10 - 12 h, then rinsed with deionized water, and annealed in air at 300 - 400 °C for 0.5 - 1 h after natural air drying to obtain rutile TiO 2 nanorod / fluorine-doped anatase TiO 2 nanosheet composite material.

[0038] According to the fourth aspect of the present invention, the present invention relates to the application of the preparation method of the above rutile TiO 2 nanorod / fluorine-doped anatase TiO 2 nanosheet composite material in the electrochromic smart window industry.

[0039] The rutile TiO 2 nanorod / fluorine-doped anatase TiO 2 nanosheet composite material and its preparation method of the present invention have the following beneficial effects:

[0040] 1. The present invention uses the hydrothermal method to grow rutile TiO 2 nanorods on a pretreated FTO conductive substrate, and then combines the solvothermal method to epitaxially grow anatase TiO 2 nanosheets on the rutile TiO 2 nanorods. The rutile TiO 2 nanorods, as a stable support framework, significantly enhance the bonding force between the TiO 2 nanosheets and the substrate, improving the cyclic stability of the composite material while also enhancing the electron transfer efficiency between the conductive substrate and the TiO 2 nanosheets.

[0041] 2. The present invention performs surface fluorination treatment on the anatase TiO 2 ​The nanosheets are subjected to surface fluorination treatment, and the fluorine-doped anatase TiO after surface fluorination treatment 2 The nanosheets can induce the enhancement of the local surface plasmon resonance effect, thereby realizing independent and selective optical transmittance modulation for visible light and near-infrared light.

[0042] 3. The rutile TiO prepared by the present invention 2 nanorods / fluorine-doped anatase TiO 2 The two-phase interface of the nanosheet composite electrochromic material is approximately a semi-coherent interface, and the lattice misfit is estimated to be 0.1, having good interfacial lattice matching, which can overcome the defects of traditional heterojunctions and alleviate the increase in interfacial resistance caused by high contact barriers and lattice mismatches.

[0043] 4. The rutile TiO of the present invention 2 nanorods / fluorine-doped anatase TiO 2 The preparation method of the nanosheet composite electrochromic material is simple in process, low in cost, and good in repeatability, which is conducive to large-scale industrial production and has good industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0045] Figure 1 For the rutile TiO obtained in Example 1 of the present invention 2 nanorods / fluorine-doped anatase TiO 2 nanosheet composite material, the pure rutile phase TiO prepared in Example 5 2 nanorod material and the fluorine-doped anatase TiO prepared in Example 6 2 XRD characterization diagrams of the nanosheet materials.

[0046] Figure 2 For the rutile TiO obtained in Example 1 of the present invention 2 nanorods / fluorine-doped anatase TiO 2 nanosheet composite material, the pure rutile phase TiO prepared in Example 5 2 nanorod material and the fluorine-doped anatase TiO prepared in Example 6 2 Raman characterization diagrams of the nanosheet materials.

[0047] Figure 3 For the rutile TiO prepared in Example 1 of the present invention 2 nanorods / fluorine-doped anatase TiO 2Nanosheet composite material, pure rutile-phase TiO prepared in Example 5 2 nanorod material and fluorine-doped anatase-phase TiO prepared in Example 6 2 SEM images of the nanosheet materials, where Figure 3 (a), (b) are SEM images of the pure rutile-phase TiO 2 nanorods, Figure 3 (c), (d) are SEM images of the fluorine-doped anatase TiO 2 nanosheets, Figure 3 (e), (f) are SEM images of the rutile TiO 2 nanorod / fluorine-doped anatase TiO 2 nanosheet composite material.

[0048] Figure 4 Rutile TiO prepared in Example 1 of the present invention 2 nanorod / fluorine-doped anatase TiO 2 Microstructure and lattice structure diagrams of the transmission electron microscope of the nanosheet composite material of rutile TiO Figure 4 (a) is the TEM morphology diagram at low magnification, Figure 4 (b) is the TEM morphology diagram at high magnification, Figure 4 (c) is Figure 4 The lattice structure diagram at high magnification of region a in (b), Figure 4 (d), (e), (f) are Figure 4 The Fourier transform diagrams of regions b, c, and d in (c).

[0049] Figure 5 Rutile TiO prepared in Example 1 of the present invention 2 nanorod / fluorine-doped anatase TiO 2 Microstructure and lattice structure diagrams of the transmission electron microscope between the two-phase interfaces of the nanosheet composite material of rutile TiO Figure 5 (a) is the TEM morphology diagram of the two-phase interface between the rutile-phase TiO 2 nanorods and the fluorine-doped anatase-phase TiO 2 nanosheets, Figure 5 (b) is the rutile-phase TiO 2 nanorods and the fluorine-doped anatase-phase TiO 2 Calculation of the lattice mismatch degree between the two-phase interfaces of the nanosheets, Figure 5 (c) is the rutile-phase TiO 2 nanorods and the fluorine-doped anatase-phase TiO 2 Schematic diagram of the semi-coherent interface between the two phases of the nanosheets.

[0050] Figure 6 Rutile TiO prepared in Example 1 of the present invention2 Nanorod / Fluorine-doped Anatase TiO 2 Elemental composition analysis diagram of the nanosheet composite material, where Figure 6 (a) is the rutile TiO prepared in Example 1 of the present invention 2 Nanorod / Fluorine-doped Anatase TiO 2 Dark field image of the transmission electron microscope of the nanosheet composite material Figure 6 (b), Figure 6 (c) and Figure 6 (d) are the electron energy spectrum diagrams of Ti atoms, O atoms and F atoms respectively.

[0051] Figure 7 is the rutile TiO prepared in Example 1 of the present invention 2 Nanorod / Fluorine-doped Anatase TiO 2 Nanosheet composite material, the pure rutile phase TiO nanorod material prepared in Example 5 2 and the fluorine-doped anatase phase TiO nanosheet material prepared in Example 6 2 Schematic diagram of the kinetic electrochromic performance at 700 nm.

[0052] Figure 8 is the rutile TiO prepared in Example 1 of the present invention 2 Nanorod / Fluorine-doped Anatase TiO 2 Nanosheet composite material, the pure rutile phase TiO2 nanorod material prepared in Example 5 and the fluorine-doped anatase phase TiO 2 Schematic diagram of the kinetic electrochromic performance at 1300 nm of the nanosheet material.

[0053] Figure 9 is the rutile TiO prepared in Example 1 of the present invention 2 Nanorod / Fluorine-doped Anatase TiO 2 Nanosheet composite material, the pure rutile phase TiO 2 Nanorod material and the fluorine-doped anatase phase TiO 2 Schematic diagram of the visible and near-infrared transmission spectral performance of the nanosheet material under different applied voltages, where Figure 9 (a) is the visible and near-infrared transmission spectral performance schematic diagram of the pure rutile phase TiO 2 nanorod under different applied voltages Figure 9 (b) is the visible and near-infrared transmission spectral performance schematic diagram of the fluorine-doped anatase phase TiO 2 nanosheet under different applied voltages Figure 9 (c) is the rutile TiO 2 Nanorod / Fluorine-doped Anatase TiO 2Schematic diagram of the visible and near-infrared transmission spectral properties of the nanosheet composite under different applied voltages.

[0054] Figure 10 Rutile TiO prepared in Example 1 of the present invention 2 nanorods / fluorine-doped anatase TiO 2 nanosheet composite and fluorine-doped anatase phase TiO prepared in Example 6 2 Kinetic cycle comparison diagram of the nanosheet material, where Figure 10 (a) is the kinetic cycle diagram of the fluorine-doped anatase phase TiO 2 nanosheet material prepared in Example 6, Figure 10 (b) is the kinetic cycle diagram of the rutile TiO 2 nanorods / fluorine-doped anatase TiO 2 nanosheet composite prepared in Example 1.

[0055] Figure 11 Rutile TiO prepared in Example 1 of the present invention 2 nanorods / fluorine-doped anatase TiO 2 Comparison diagram of the visible light and near-infrared region transmission spectra of the rutile TiO

[0056] Figure 12 Rutile TiO prepared in Example 2 of the present invention 2 nanorods / fluorine-doped anatase TiO 2 Schematic diagram of the kinetic electrochromic performance of the rutile TiO

[0057] Figure 13 Rutile TiO prepared in Example 2 of the present invention 2 nanorods / fluorine-doped anatase TiO 2 Schematic diagram of the kinetic electrochromic performance of the rutile TiO

[0058] Figure 14 Rutile TiO prepared in Example 3 of the present invention 2 nanorods / fluorine-doped anatase TiO 2 Schematic diagram of the kinetic electrochromic performance of the rutile TiO

[0059] Figure 15 Rutile TiO prepared in Example 3 of the present invention 2 nanorods / fluorine-doped anatase TiO 2 Schematic diagram of the kinetic electrochromic performance of the rutile TiO

[0060] Figure 16Rutile TiO prepared in Example 4 of the present invention 2 nanorods / fluorine-doped anatase TiO 2 Schematic diagram of the kinetic electrochromic performance of the nanosheet composite at 700 nm.

[0061] Figure 17 Rutile TiO prepared in Example 4 of the present invention 2 nanorods / fluorine-doped anatase TiO 2 Schematic diagram of the kinetic electrochromic performance of the nanosheet composite at 1300 nm. Detailed implementation manners

[0062] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0063] It should be noted that, without conflict, the following embodiments and the features in the embodiments may be combined with each other; and, based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present disclosure.

[0064] It should be noted that the following describes various aspects of the embodiments within the scope of the appended claims. It should be apparent that the aspects described herein may be embodied in a wide variety of forms, and any specific structure and / or function described herein is illustrative only. Based on the present disclosure, those skilled in the art should understand that one aspect described herein may be implemented independently of any other aspect, and two or more of these aspects may be combined in various ways. For example, any number of aspects described herein may be used to implement the device and / or practice the method. In addition, this device and / or practice this method may be implemented using other structures and / or functions in addition to one or more of the aspects described herein.

[0065] Example 1

[0066] Rutile-phase TiO 2 nanorods / fluorine-doped anatase-phase TiO 2 Preparation of the nanosheet composite:

[0067] Step 1. Pretreatment of the FTO conductive glass substrate

[0068] The FTO conductive glass substrate was successively placed in acetone, ethanol, and deionized water, and ultrasonically cleaned for 15 min respectively, and then dried with nitrogen to obtain a pretreated FTO conductive glass substrate;

[0069] Step 2. Preparation of the precursor solution A

[0070] Add tetrabutyl titanate and 12 mol / L concentrated hydrochloric acid to deionized water according to the ratio. Among them, the volumes of tetrabutyl titanate, concentrated hydrochloric acid and deionized water are 2 mL, 10 mL and 15 mL respectively. After stirring, the precursor solution A is obtained;

[0071] Step 3. Preparation of rutile TiO 2 nanorods

[0072] Fix the conductive side of the pretreated FTO conductive glass substrate downward at 45° in the precursor solution A prepared in Step 2 for hydrothermal reaction. The hydrothermal reaction temperature is 140 °C and the hydrothermal reaction time is 3 h. After naturally cooling to room temperature, rinse with deionized water and dry in air at 80 °C for 12 h. Finally, anneal in air at 450 °C for 0.5 h to obtain rutile TiO 2 nanorods;

[0073] Step 4. Preparation of precursor solution B

[0074] Add tetrabutyl titanate, triethanolamine and hydrofluoric acid to n-butanol according to the ratio. Among them, the contents of tetrabutyl titanate, triethanolamine, hydrofluoric acid and n-butanol are 160 μL, 5 mL, 160 μL and 15 mL respectively. After stirring, the precursor solution B is obtained;

[0075] Step 5. Preparation of anatase TiO 2 nanosheets

[0076] Fix the conductive side of the FTO conductive glass substrate with rutile TiO 2 nanorods downward at 45° in the precursor solution B prepared in Step 4. After mixing, place it in a reaction kettle and carry out solvothermal reaction under nitrogen protection. The solvothermal reaction temperature is 150 °C and the solvothermal reaction time is 12 h. After naturally cooling to room temperature, rinse with deionized water and dry at 80 °C for 12 h. On the FTO conductive glass substrate containing rutile TiO 2 nanorods, anatase TiO 2 nanosheets are obtained;

[0077] Step 6. Surface fluorination treatment

[0078] Immerse the anatase TiO 2 nanosheets prepared in Step 5 in a NaF solution with a concentration of 0.5x10 -2 mol / L for 10, then rinse with deionized water, air dry and anneal in air at 300 °C for 0.5 h to obtain rutile TiO 2 nanorods / fluorine-doped anatase TiO 2 nanosheet composite material.

[0079] Example 2

[0080] Rutile TiO 2 nanorod / doped anatase TiO 2 Preparation of nanosheet composite:

[0081] Step 1. Pretreatment of FTO conductive glass substrate

[0082] Place the FTO conductive glass substrate in acetone, ethanol, and deionized water in sequence, perform ultrasonic cleaning for 15 min respectively, and then dry it with nitrogen to obtain the pretreated FTO conductive glass substrate;

[0083] Step 2. Preparation of precursor solution A

[0084] Add tetrabutyl titanate and 12 mol / L concentrated hydrochloric acid to deionized water according to the ratio. Among them, the volumes of tetrabutyl titanate, concentrated hydrochloric acid, and deionized water are 2.2 mL, 12 mL, and 15 mL respectively. After stirring, precursor solution A is obtained;

[0085] Step 3. Preparation of rutile TiO 2 nanorods

[0086] Fix the conductive surface of the pretreated FTO conductive glass substrate obtained in Step 1 downward at 45° in the precursor solution A prepared in Step 2 for hydrothermal reaction. The hydrothermal reaction temperature is 142 °C, and the hydrothermal reaction time is 3.2 h. After natural cooling to room temperature, rinse with deionized water and dry in air at 80 °C for 12 h. Finally, anneal in air at 450 °C for 0.6 h to obtain rutile TiO 2 nanorods;

[0087] Step 4. Preparation of precursor solution B

[0088] Add tetrabutyl titanate, triethanolamine, and hydrofluoric acid to n-butanol according to the ratio. Among them, the contents of tetrabutyl titanate, triethanolamine, hydrofluoric acid, and n-butanol are 200 μL, 8 mL, 200 μL, and 15 mL respectively. After stirring, precursor solution B is obtained;

[0089] Step 5. Preparation of anatase TiO 2 nanosheets

[0090] The rutile TiO prepared in Step 3 2The conductive surface of the FTO conductive glass substrate with nanorods is fixed downward at 45° in the precursor solution B prepared in Step 4. After mixing, it is placed in a reaction kettle and subjected to a solvothermal reaction under nitrogen protection. The solvothermal reaction temperature is 160 °C, and the solvothermal reaction time is 14 h. After natural cooling to room temperature, it is rinsed with deionized water and dried at 85 °C for 13 h. Anatase TiO 2 nanosheets are prepared on the FTO conductive glass substrate with nanorods; 2

[0091] Step 6. Surface fluorination treatment

[0092] The anatase TiO 2 nanosheets prepared in Step 5 are immersed in a NaF solution with a concentration of 0.6×10 -2 mol / L for 10 h, then rinsed with deionized water, and annealed in air at 320 °C for 0.6 h after natural air drying to obtain rutile TiO 2 nanorod / fluorine-doped anatase TiO 2 nanosheet composite material.

[0093] Example 3

[0094] Preparation of rutile TiO 2 nanorod / fluorine-doped anatase TiO 2 nanosheet composite material:

[0095] Step 1. Pretreatment of FTO conductive glass substrate

[0096] The FTO conductive glass substrate is successively placed in acetone, ethanol, and deionized water, ultrasonically cleaned for 15 min respectively, and then dried with nitrogen to obtain a pretreated FTO conductive glass substrate;

[0097] Step 2. Preparation of precursor solution A

[0098] Tetrabutyl titanate and 12 mol / L concentrated hydrochloric acid are added to deionized water according to the ratio. Among them, the volumes of tetrabutyl titanate, concentrated hydrochloric acid, and deionized water are 2.4 mL, 13 mL, and 15 mL respectively. After stirring, precursor solution A is obtained;

[0099] Step 3. Preparation of rutile TiO 2 nanorods

[0100] ​Fix the conductive surface of the FTO conductive glass substrate pretreated in Step 1 downward at 45° in the precursor solution A prepared in Step 2 for hydrothermal reaction. The hydrothermal reaction temperature is 144 °C and the hydrothermal reaction time is 3.4 h. After natural cooling to room temperature, rinse with deionized water and dry in air at 80 °C for 12 h. Finally, anneal in air at 450 °C for 0.7 h to obtain rutile phase TiO 2 nanorods;

[0101] Step 4: Preparation of precursor solution B

[0102] Add tetrabutyl titanate, triethanolamine, and hydrofluoric acid to n-butanol according to the ratio. Among them, the contents of tetrabutyl titanate, triethanolamine, hydrofluoric acid, and n-butanol are 220 μL, 10 mL, 220 μL, and 15 mL respectively. After stirring, obtain precursor solution B;

[0103] Step 5: Preparation of anatase phase TiO 2 nanosheets

[0104] Fix the conductive surface of the FTO conductive glass substrate with rutile phase TiO 2 nanorods downward at 45° in the precursor solution B prepared in Step 4. After mixing, place it in a reaction kettle and carry out solvothermal reaction under nitrogen protection. The solvothermal reaction temperature is 170 °C and the solvothermal reaction time is 16 h. After natural cooling to room temperature, rinse with deionized water and dry at 90 °C for 14 h. On the FTO conductive glass substrate containing rutile phase TiO 2 nanorods, obtain anatase phase TiO 2 nanosheets;

[0105] Step 6: Surface fluorination treatment

[0106] Immerse the anatase phase TiO 2 nanosheets prepared in Step 5 in a NaF solution with a concentration of 0.8x10 -2 mol / L for 11 h, then rinse with deionized water, air dry, and anneal in air at 340 °C for 0.8 h to obtain rutile phase TiO 2 nanorods / fluorine-doped anatase phase TiO 2 nanosheet composite material.

[0107] Example 4

[0108] Preparation of rutile phase TiO 2 nanorods / fluorine-doped anatase phase TiO 2 nanosheet composite material:

[0109] Step 1: Pretreatment of FTO conductive glass substrate

[0110] The FTO conductive glass substrate was successively placed in acetone, ethanol, and deionized water, ultrasonically cleaned for 15 minutes respectively, and then dried with nitrogen to obtain a pretreated FTO conductive glass substrate;

[0111] Step 2: Preparation of precursor solution A

[0112] Tetrabutyl titanate and 12 mol / L concentrated hydrochloric acid were added to deionized water according to the ratio. Among them, the volumes of tetrabutyl titanate, concentrated hydrochloric acid, and deionized water were 3 mL, 15 mL, and 15 mL respectively. After stirring, precursor solution A was obtained;

[0113] Step 3: Preparation of rutile TiO 2 nanorods

[0114] The conductive surface of the pretreated FTO conductive glass substrate obtained in Step 1 was fixed downward at 45° in the precursor solution A prepared in Step 2 for hydrothermal reaction. The hydrothermal reaction temperature was 150 °C, and the hydrothermal reaction time was 4 h. After natural cooling to room temperature, it was rinsed with deionized water and dried in air at 80 °C for 12 h. Finally, it was annealed in air at 450 °C for 1 h to obtain rutile TiO 2 nanorods on the FTO conductive glass substrate;

[0115] Step 4: Preparation of precursor solution B

[0116] Tetrabutyl titanate, triethanolamine, and hydrofluoric acid were added to n-butanol according to the ratio. Among them, the contents of tetrabutyl titanate, triethanolamine, hydrofluoric acid, and n-butanol were 320 μL, 15 mL, 320 μL, and 15 mL respectively. After stirring, precursor solution B was obtained;

[0117] Step 5: Preparation of anatase TiO 2 nanosheets

[0118] The FTO conductive glass substrate with rutile TiO 2 nanorods prepared in Step 3 was fixed downward at 45° in the precursor solution B prepared in Step 4. After mixing, it was placed in a reaction kettle and subjected to solvothermal reaction under nitrogen protection. The solvothermal reaction temperature was 200 °C, and the solvothermal reaction time was 20 h. After natural cooling to room temperature, it was rinsed with deionized water and dried at 100 °C for 16 h to obtain anatase TiO 2 nanosheets on the FTO conductive glass substrate with rutile TiO 2 nanorods;

[0119] Step 6: Surface fluorination treatment

[0120] The anatase TiO 2The nanosheets were immersed in a NaF solution with a concentration of 1x10 -2 mol / L for 12 h, rinsed with deionized water, air-dried naturally, and then annealed in air at 400 °C for 1 h to obtain rutile-phase TiO 2 nanorods / flourine-doped anatase-phase TiO 2 nanosheet composites.

[0121] Example 5

[0122] This example was used as Comparative Example 1 for Examples 1 to 4 to prepare pure rutile-phase TiO 2 nanorod materials. The specific steps were as follows:

[0123] Step 1. Pretreatment of the FTO conductive glass substrate

[0124] The FTO conductive glass substrate was successively placed in acetone, ethanol, and deionized water, ultrasonically cleaned for 15 min respectively, and then dried with nitrogen to obtain a pretreated FTO conductive glass substrate;

[0125] Step 2. Preparation of precursor solution A

[0126] Tetrabutyl titanate and concentrated hydrochloric acid with a concentration of 12 mol / L were added to deionized water according to the ratio. Among them, the volumes of tetrabutyl titanate, concentrated hydrochloric acid, and deionized water were 3 mL, 15 mL, and 15 mL respectively. After stirring, precursor solution A was obtained;

[0127] Step 3. Preparation of rutile-phase TiO 2 nanorods

[0128] The conductive surface of the FTO conductive glass substrate pretreated in Step 1 was fixed downward at 45° in the precursor solution A prepared in Step 2 for hydrothermal reaction. The hydrothermal reaction temperature was 150 °C, and the hydrothermal reaction time was 4 h. After natural cooling to room temperature, it was rinsed with deionized water and dried in air at 80 °C for 12 h. Finally, it was annealed in air at 450 °C for 1 h to obtain rutile-phase TiO 2 nanorods on the FTO conductive glass substrate.

[0129] Example 6

[0130] This example was Comparative Example 2 for Examples 1 to 4 to prepare fluorine-doped anatase-phase TiO 2 nanosheet materials. The specific steps were as follows:

[0131] Step 1. Pretreatment of the FTO conductive glass substrate

[0132] The FTO conductive glass substrate was successively placed in acetone, ethanol, and deionized water, ultrasonically cleaned for 15 min respectively, and then dried with nitrogen to obtain the pretreated FTO conductive glass substrate;

[0133] Step 2: Preparation of precursor solution B

[0134] Tetrabutyl titanate, triethanolamine, and hydrofluoric acid were added to n-butanol according to the ratio. Among them, the contents of tetrabutyl titanate, triethanolamine, hydrofluoric acid, and n-butanol were 160 μL, 5 mL, 160 μL, and 15 mL respectively. After stirring, precursor solution B was obtained;

[0135] Step 3: Preparation of anatase TiO 2 nanosheets

[0136] The conductive surface of the pretreated FTO conductive glass substrate prepared in Step 1 was fixed downward at 45° in the precursor solution B prepared in Step 2. After mixing, it was placed in a reaction kettle and subjected to a solvothermal reaction under nitrogen protection. The solvothermal reaction temperature was 150 °C, and the solvothermal reaction time was 12 h. After natural cooling to room temperature, it was rinsed with deionized water and dried at 80 °C for 12 h to obtain anatase TiO 2 nanosheets;

[0137] Step 4: Surface fluorination treatment

[0138] The anatase TiO 2 nanosheets prepared in Step 3 were soaked in a NaF solution with a concentration of 0.5×10 -2 mol / L for 10 h, then rinsed with deionized water, air-dried naturally, and annealed in air at 300 °C for 0.5 h to obtain fluorine-doped anatase TiO 2 nanosheet material.

[0139] Example 7

[0140] An X-ray diffractometer (XRD, Rigaku D / MAX2500V) was used to test and observe the structures of the rutile TiO 2 nanorod / fluorine-doped anatase TiO 2 nanosheet composite material prepared in Example 1, the pure rutile TiO 2 nanorod material prepared in Example 5, and the fluorine-doped anatase TiO 2 nanosheet material prepared in Example 6. The test results are shown in Figure 1 .

[0141] As Figure 1 shown, the fluorine-doped anatase TiO 2 nanosheet material prepared in Example 6 and the rutile TiO prepared in Example 12 Nanorod / Fluorine-doped Anatase TiO 2 nanosheet composite is also of the anatase type TiO 2 . The TiO 2 nanorod film prepared in Example 5 is of the rutile phase TiO 2 . This is because the rutile phase TiO 2 nanorod / fluorine-doped anatase TiO 2 nanosheet composite has a relatively thin rutile phase TiO 2 nanorod layer, so its XRD peaks are not obvious. While the pure rutile TiO 2 nanorod material prepared in Example 5 has a more complete film growth due to the higher hydrothermal temperature and longer time, so it can exhibit the characteristic peaks of the rutile phase TiO 2 .

[0142] The structure of the rutile phase TiO 2 nanorod / fluorine-doped anatase TiO 2 nanosheet composite prepared in Example 1, the pure rutile phase TiO 2 nanorod material prepared in Example 5, and the fluorine-doped anatase TiO 2 nanosheet material prepared in Example 6 was tested and observed using a confocal micro-Raman spectrometer (LabRAM HR Evolution). The test results are shown in Figure 2 .

[0143] As Figure 2 shown, the Raman spectra of the rutile phase TiO 2 nanorod / fluorine-doped anatase TiO 2 nanosheet composite prepared in Example 1 and the fluorine-doped anatase TiO 2 nanosheet film prepared in Example 6 exhibit vibration modes at approximately 148 cm -1 , 375 cm -1 , 510 cm -1 and 625 cm -1 respectively, which are consistent with the E 2 , B g , A 1g +B 1g and E 1g vibration modes of the anatase structure TiO g . While the Raman spectrum of the pure rutile phase TiO 2 nanorod film prepared in Example 5 exhibits vibration modes at approximately 249 cm -1 , 445 cm -1 and 610 cm -1 respectively, which are consistent with the vibration modes of the rutile structure TiO 2The multi-phonon process, E g and A 1g are consistent with the Raman vibration mode. This indicates that TiO 2 nanorods are in the rutile structure, while the fluorine-doped TiO 2 nanosheet film is in the anatase structure.

[0144] The morphology of the rutile-phase TiO 2 nanorods / fluorine-doped anatase-phase TiO 2 nanosheet composites prepared in Example 1, the pure rutile-phase TiO 2 nanorod material prepared in Example 5, and the fluorine-doped anatase-phase TiO 2 nanosheet material prepared in Example 6 was tested and observed. See Figure 3 , among which, the morphology of the pure rutile-phase TiO 2 nanorod material prepared in Example 5 is shown in Figure 3 (a), Figure 3 (b), the morphology of the fluorine-doped anatase TiO 2 nanosheet material prepared in Example 6 is shown in Figure 3 (c), Figure 3 (d), and the morphology of the rutile-phase TiO 2 nanorods / fluorine-doped anatase-phase TiO 2 nanosheet composites prepared in Example 1 is shown in Figure 3 (e), Figure 3 (f).

[0145] As Figure 3 (a) shows, the pure rutile-phase TiO 2 nanorod film grows vertically on the FTO conductive glass. As Figure 3 (b) shows, the fluorine-doped anatase-phase TiO 2 nanosheet film grows with regular cross arrangements of the lamellae. Figure 3 (c) shows that the nanosheets of the rutile-phase TiO 2 nanorods / fluorine-doped anatase-phase TiO 2 nanosheet composites prepared in Example 1 grow between the TiO 2 nanorods, forming a new interpenetrating structure. This hierarchical composite porous structure will be beneficial to the penetration of the electrolyte, help improve the diffusion efficiency of ions and electrochemical behavior, accelerate the reaction kinetics process, and improve the response speed of the electrochromic material. And compared with the FTO conductive substrate, the lattice matching degree between the anatase phase and the rutile phase is higher, which can provide favorable conditions for the nucleation of TiO 2 nanosheets, serve as its growth template, and the TiO 2The nanorods are beneficial to increasing the bonding force between the film and the FTO substrate, thereby improving the electrochromic cycling stability.

[0146] The rutile TiO₂ nanorods / flour-doped anatase TiO₂ nanosheet composites prepared in Example 1 were tested and observed for their microstructure and lattice structure by using a field emission transmission electron microscope (JEM-2100F). See 2 rutile TiO₂ 2 nanorods / flour-doped anatase TiO₂ Figure 4 , wherein the morphology of the rutile TiO₂ 2 nanorods / flour-doped anatase TiO₂ 2 nanosheet composites prepared in Example 1 at low magnification is shown in Figure 4 (a), and the morphology and lattice structure diagrams of the rutile TiO₂ 2 nanorods / flour-doped anatase TiO₂ 2 nanosheet composites prepared in Example 1 at high magnification are shown in Figure 4 (b) and Figure 4 (c) respectively. The Fourier transform diagrams of different interface regions of the rutile TiO₂ 2 nanorods / flour-doped anatase TiO₂ 2 nanosheet composites prepared in Example 1 are shown in Figure 4 (d), Figure 4 (e) and Figure 4 (f).

[0147] As shown in Figure 4 (a) and Figure 4 (b), there is a close interfacial contact between the rutile TiO₂ 2 nanorods and the flour-doped anatase TiO₂ 2 nanosheets in the rutile TiO₂ 2 nanorods / flour-doped anatase TiO₂ 2 nanosheet composites prepared in Example 1. As shown in Figure 4 (c), Figure 4 (d), Figure 4 (e) and Figure 4 (f), the flour-doped anatase TiO₂ nanosheets preferentially nucleate on the surface of the rutile nanorods and epitaxially grow along their (111) plane in the rutile TiO₂ 2 nanorods / flour-doped anatase TiO₂ 2 nanosheet composites prepared in Example 1, and the main exposed surface of the flour-doped anatase TiO₂ 2 nanosheets is the (001) plane. The exposure of the (001) active plane can reduce the embedding barrier of metal ions, which is beneficial to the embedding of lithium ions and thus improves the ion diffusion rate.

[0148] The rutile phase TiO prepared in Example 1 was observed by field emission transmission electron microscopy (JEM-2100F). 2 Nanorods / Fluorine-doped anatase TiO 2 The organization and lattice structure between the two phase interfaces of the nanosheet composite material were tested and observed, see Figure 5 , wherein the rutile phase TiO prepared in Example 1 under high magnification 2 Nanorods / Fluorine-doped anatase TiO 2 For the morphology and lattice structure of the two-phase interface of the nanosheet composite material, see Figure 5 (a), rutile phase TiO prepared in Example 1 2 Nanorods / Fluorine-doped anatase TiO 2 Rutile phase TiO nanosheet composites 2 Nanorods and fluorine-doped anatase TiO 2 For the calculation of lattice mismatch between the two phase interfaces of nanosheets, see Figure 5 (b), rutile phase TiO prepared in Example 1 2 Nanorods / Fluorine-doped anatase TiO 2 Rutile phase TiO nanosheet composites 2 Nanorods and fluorine-doped anatase TiO 2 Schematic diagram of semi-coherent interface between two phases of nanosheets, see Figure 5 (c).

[0149] If Figure 5 (a) shows the rutile phase TiO prepared in Example 1 2 Nanorods / Fluorine-doped anatase TiO 2 A clear isomorphous phase connection is formed at the interface between rutile and anatase phases in the nanosheet composite. Figure 5 (b) and Figure 5 (c) shows the rutile phase TiO prepared in Example 1 2 Nanorods / Fluorine-doped anatase TiO 2 Rutile TiO in Nanosheet Composites 2 Nanorods and fluorine-doped anatase TiO 2 The lattice mismatch between the nanosheets is about 0.1, indicating that a semi-coherent interface region with a high lattice matching degree is formed between the rutile and anatase phases.

[0150] Field emission transmission electron microscopy (JEM-2100F) was used to examine the rutile phase TiO prepared in Example 1 2 Nanorods / Fluorine-doped anatase TiO 2 Analysis of the elemental composition of nanosheet composites, see Figure 6 , where dark field images of transmission electron microscope refer to​​​​Figure 6 (a), the electronic energy spectra of Ti atoms, O atoms and F atoms are shown in Figure 6 (b), 6(c) and 6(d).

[0151] Rutile phase TiO prepared in Example 1 2 Nanorods / Fluorine-doped anatase TiO 2 Transmission electron microscope dark field image of nanosheet composite material is as follows Figure 6 (a) shows that the electronic energy spectra of Ti atoms, O atoms and F atoms are shown in Figure 6 (b), 6(c) and 6(d). It can be observed that titanium, oxygen and fluorine atoms are evenly distributed without other impurities. The successful incorporation of fluorine ions can induce anatase TiO 2 The increase in oxygen defect concentration in nanosheets and the improvement in carrier concentration are expected to achieve independent modulation of the near-infrared band.

[0152] The rutile phase TiO obtained in Example 1, Example 2, Example 3 and Example 4 was tested as follows. 2 Nanorods / Fluorine-doped anatase TiO 2 Dynamics, visible and near-infrared transmission spectra of nanosheet composites:

[0153] Using an electrochemical workstation (CHI760E) and a UV-visible-near infrared spectrophotometer (UV-3600, Japan), in a three-electrode system (the electrochromic film on the FTO substrate was the working electrode, Ag / AgCl was the reference electrode, platinum wire was the counter electrode, and 1.0 M LiClO 4 / PC solution as electrolyte) to record the electrochemical and electrochromic properties of the samples. To ensure that the light path is unobstructed, the reference electrode and the counter electrode are placed on one side of the working electrode, and the reference electrode and the counter electrode are placed on one side. The transmission spectrum was recorded in the wavelength range of 250 to 1650nm at a voltage of -1.5V to +1.5V. By applying a square wave voltage of -1.5V (60 seconds) and +1.5V (60 seconds) at 700nm, and a square wave voltage of -1V (30 seconds) and +1.5V (30 seconds) at 1300nm, the dynamic optical transmittance changes at 700nm and 1300nm were recorded.

[0154] Figure 7 Rutile phase TiO prepared in Example 1 of the present invention 2 Nanorods / Fluorine-doped anatase TiO 2 Nanosheet composite material, pure rutile phase TiO prepared in Example 5 2 Nanorod material and fluorine-doped anatase phase TiO prepared in Example 6 2 Schematic diagram of the kinetic electrochromic performance of nanosheet materials at 700nm.​​

[0155] Figure 8 For the rutile TiO₂ prepared in Example 1 of the present invention 2 nanorods / fluorine-doped anatase TiO₂ 2 nanosheet composite material, the pure rutile TiO₂ prepared in Example 5 2 nanorod material and the fluorine-doped anatase TiO₂ prepared in Example 6 2 Schematic diagram of the kinetic electrochromic performance at 1300 nm of the nanosheet material.

[0156] Figure 9 For the rutile TiO₂ prepared in Example 1 of the present invention 2 nanorods / fluorine-doped anatase TiO₂ 2 nanosheet composite material, the pure rutile TiO₂ prepared in Example 5 2 nanorod material and the fluorine-doped anatase TiO₂ prepared in Example 6 2 Schematic diagram of the visible and near-infrared transmission spectral performance of the nanosheet material under different applied voltages. Among them, for the pure rutile TiO₂ 2 Schematic diagram of the visible and near-infrared transmission spectral performance of the nanorod material under different applied voltages, see Figure 9 (a), for the fluorine-doped anatase TiO₂ prepared in Example 6 2 Schematic diagram of the visible and near-infrared transmission spectral performance of the nanosheet material under different applied voltages, see Figure 9 (b), for the rutile TiO₂ prepared in Example 1 2 nanorods / fluorine-doped anatase TiO₂ 2 Schematic diagram of the visible and near-infrared transmission spectral performance of the nanosheet composite material under different applied voltages, see Figure 9 (c).

[0157] As Figure 7 、 Figure 8 and Figure 9 (a) shows that for the pure rutile TiO₂ nanorod material prepared in Example 5, the coloring time and fading time at 700 nm are 38.1 s and 9.0 s respectively, and the contrast ratios at 700 nm and 1300 nm are 5.2% and 4.8% respectively, and it hardly has the visible light and near-infrared modulation functions. As 2 Figure 7 、 Figure 8 Figure 9 and Figure 7 (b) shows that for the fluorine-doped anatase TiO₂ nanosheet material prepared in Example 6, the coloring time and fading time at 700 nm are 28.2 s and 8.7 s respectively, and the contrast ratios at 700 nm and 1300 nm are 65.1% and 60.2% respectively. As​​Figure 7 , Figure 8 and Figure 9 As shown in (c), the coloring time and fading time of the rutile TiO 2 nanorod / fluorine-doped anatase TiO 2 nanosheet composite material at 700 nm are 22.1 s and 8.0 s respectively, and the contrast ratios at 700 nm and 1300 nm are 70% and 63.8% respectively. Its visible light and near-infrared transmittance modulation capabilities are significantly improved, the coloring and fading times are significantly reduced, and it has excellent dual-band selective modulation capabilities.

[0158] Figure 10 This is the kinetic cycle comparison diagram of the rutile TiO 2 nanorod / fluorine-doped anatase TiO 2 nanosheet composite material prepared in Example 1 of the present invention and the fluorine-doped anatase TiO 2 nanosheet material prepared in Example 6. Among them, the kinetic cycle diagram of the fluorine-doped anatase TiO 2 nanosheet material prepared in Example 6 can be seen in Figure 10 (a), and the kinetic cycle diagram of the rutile TiO 2 nanorod / fluorine-doped anatase TiO 2 nanosheet composite material prepared in Example 1 can be seen in Figure 10 (b).

[0159] As Figure 10 (a) shows, if rutile TiO 2 nanorods are not prepared in advance on the FTO substrate, the fluorine-doped anatase TiO 2 nanosheet film directly grown almost loses its electrochromic ability after 100 cycles. As Figure 10 (b) shows, the presence of rutile TiO 2 nanorods enables the rutile TiO 2 nanorod / fluorine-doped anatase TiO 2 nanosheet composite material prepared in Example 1 to still maintain good electrochromic ability after 2000 coloring and fading cycles, and the optical modulation amplitude does not decrease significantly.

[0160] Figure 11 This is the comparison diagram of the visible light and near-infrared region transmission spectra of the rutile TiO 2 nanorod / fluorine-doped anatase TiO 2 nanosheet composite material prepared in Example 1 of the present invention before and after 2000 cycles under different applied voltages.

[0161] As Figure 11As shown, the rutile TiO prepared in Example 1 2 nanorods / fluorine-doped anatase TiO 2 nanosheet composite material can still exhibit visible light and near-infrared independent selective modulation capabilities at different voltages after 2000 coloring and fading cycles, and has excellent cycle stability. Specifically, the rutile TiO prepared in Example 1 2 nanorods / fluorine-doped anatase TiO 2 nanosheet composite material has no decrease in the optical modulation amplitude at 700 nm after 2000 coloring and fading cycles, and the optical modulation amplitude at 1300 nm only decreases by 16.7% (63.8% before cycling and 53.1% after cycling, a decrease of 10.7%, and the decrease ratio is 16.7%), and has good visible light and near-infrared selective independent modulation capabilities.

[0162] The rutile TiO prepared in Example 2 2 nanorods / fluorine-doped anatase TiO 2 Schematic diagram of the kinetic electrochromic performance of the nanosheet composite material at 700 nm is shown in Figure 12 .

[0163] The rutile TiO prepared in Example 2 2 nanorods / fluorine-doped anatase TiO 2 Schematic diagram of the kinetic electrochromic performance of the nanosheet composite material at 1300 nm is shown in Figure 13 .

[0164] As Figure 12 and Figure 13 shown, the rutile TiO prepared in Example 2 2 nanorods / fluorine-doped anatase TiO 2 The coloring time and fading time of the nanosheet composite material at 700 nm are 28.6 s and 8.3 s respectively, and the contrast ratios at 700 nm and 1300 nm are 62.1% and 63.4% respectively.

[0165] The rutile TiO prepared in Example 3 2 nanorods / fluorine-doped anatase TiO 2 Schematic diagram of the kinetic electrochromic performance of the nanosheet composite material at 700 nm is shown in Figure 14 .

[0166] The rutile TiO prepared in Example 3 2 nanorods / fluorine-doped anatase TiO 2 Schematic diagram of the kinetic electrochromic performance of the nanosheet composite material at 1300 nm is shown in Figure 15 .

[0167] As Figure 14 and Figure 15 shown, the coloring time and fading time of the rutile-phase TiO 2 nanorods / flourine-doped anatase-phase TiO 2 nanosheet composite prepared in Example 3 are 27.2 s and 8.5 s respectively at 700 nm, and the contrasts at 700 nm and 1300 nm are 59.8% and 50.3% respectively.

[0168] For the rutile-phase TiO 2 nanorods / flourine-doped anatase-phase TiO 2 nanosheet composite prepared in Example 4, see the schematic diagram of the kinetic electrochromic performance at 700 nm in Figure 16 .

[0169] For the rutile-phase TiO 2 nanorods / flourine-doped anatase-phase TiO 2 nanosheet composite prepared in Example 4, see the schematic diagram of the kinetic electrochromic performance at 1300 nm in Figure 17 .

[0170] As Figure 16 and Figure 17 shown, the coloring time and fading time of the rutile-phase TiO 2 nanorods / flourine-doped anatase-phase TiO 2 nanosheet composite prepared in Example 4 are 31.1 s and 9.3 s respectively at 700 nm, and the contrasts at 700 nm and 1300 nm are 57.2% and 57.6% respectively.

[0171] 1. The present invention uses a hydrothermal method to grow rutile-phase TiO 2 nanorods on a pretreated FTO conductive substrate, and then combines a solvothermal method to epitaxially grow anatase-phase TiO 2 nanosheets on the rutile-phase TiO 2 nanorods. The rutile-phase TiO 2 nanorods, as a stable support framework, significantly enhance the binding force between the TiO 2 nanosheets and the substrate, improve the cycle stability of the composite material, and also improve the electron transfer efficiency between the conductive substrate and the TiO 2 nanosheets.

[0172] 2. The present invention performs a surface fluorination treatment on the anatase-phase TiO 2 nanosheets. The fluorine-doped anatase-phase TiO 2 nanosheets after the surface fluorination treatment can induce an enhancement of the local surface plasmon resonance effect, thereby achieving independent and selective optical transmittance modulation for visible light and near-infrared light.

[0173] 3. The rutile TiO prepared by the present invention 2 nanorods / fluorine-doped anatase TiO 2 The two-phase interface of the nanosheet composite electrochromic material is approximately a semi-coherent interface, and the lattice mismatch degree is estimated to be 0.1, having good interfacial lattice matching, which can overcome the defects of traditional heterojunctions and alleviate the increase in interfacial resistance caused by high contact barriers and lattice mismatches.

[0174] 4. The rutile TiO of the present invention 2 nanorods / fluorine-doped anatase TiO 2 The preparation method of the nanosheet composite electrochromic material of the present invention is simple in process, low in cost, good in repeatability, conducive to large-scale industrial production, and has good industrial application prospects.

[0175] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A rutile phase TiO2 nanorod / fluorine-doped anatase phase TiO2 nanosheet composite material, characterized in that: The rutile phase TiO2 nanorod / fluorine-doped anatase phase TiO2 nanosheet composite material is composed of an FTO conductive glass substrate and rutile phase TiO2 nanorods and fluorine-doped anatase phase TiO2 nanosheets sequentially grown on one side of the FTO conductive glass substrate. The rutile phase TiO2 nanorod / fluorine-doped anatase phase TiO2 nanosheet composite material is prepared by inducing the growth of one-dimensional single crystal rutile phase TiO2 nanorods on the surface of a pretreated FTO conductive glass substrate in a precursor solution A by a hydrothermal method, and then inducing the growth of one-dimensional single crystal rutile phase TiO2 nanorods on the surface of a pretreated FTO conductive glass substrate in a precursor solution B by a solvothermal method. The anatase phase TiO2 nanosheets were in-situ epitaxially grown on one-dimensional single crystal rutile phase TiO2 nanorods, and the anatase phase TiO2 nanosheets were surface fluorinated with NaF solution, wherein the precursor solution A was prepared by 2-3mL tetrabutyl titanate, 10-15mL concentrated hydrochloric acid and 15ml deionized water, and the precursor solution B was prepared by 160-320μL tetrabutyl titanate, 5-15mL triethanolamine, 160-320μL hydrofluoric acid and 15mL n-butanol, and the concentration of the NaF solution used for surface treatment was 0.5x10 -2 -1x10 -2 mol / L.

2. The rutile phase TiO2 nanorod / fluorine-doped anatase phase TiO2 nanosheet composite material according to claim 1, characterized in that: The rutile phase TiO2 nanorods / fluorine-doped anatase phase TiO2 nanosheet composite material is prepared according to the following steps: Step 1: Pretreatment of FTO conductive glass substrate The FTO conductive glass substrate was placed in acetone, ethanol and deionized water in turn, and ultrasonically cleaned for 15 min respectively, and then dried with nitrogen to obtain a pretreated FTO conductive glass substrate; Step 2: Preparation of precursor solution A Tetrabutyl titanate and 12 mol / L concentrated hydrochloric acid are added to deionized water according to a ratio, wherein the volumes of tetrabutyl titanate, concentrated hydrochloric acid and deionized water are 2-3 mL, 10-15 mL and 15 ml, respectively, and a precursor solution A is obtained after stirring; Step 3: Preparation of rutile phase TiO2 nanorods The conductive surface of the FTO conductive glass substrate pretreated in step 1 is fixed at 45° downward in the precursor solution A prepared in step 2 for hydrothermal reaction at a temperature of 140-150°C for 3-4 hours. After naturally cooling to room temperature, the substrate is rinsed with deionized water and dried in air at 80°C for 12 hours. Finally, the substrate is annealed in air at 450°C for 0.5-1 hour to obtain rutile phase TiO2 nanorods on the FTO conductive glass substrate. Step 4: Preparation of precursor solution B Tetrabutyl titanate, triethanolamine and hydrofluoric acid are added to n-butanol according to a ratio, wherein the contents of tetrabutyl titanate, triethanolamine, hydrofluoric acid and n-butanol are 160-320 μL, 5-15 mL, 160-320 μL and 15 mL, respectively, and a precursor solution B is obtained after stirring; Step 5: Preparation of anatase phase TiO2 nanosheets The conductive surface of the FTO conductive glass substrate with rutile phase TiO2 nanorods prepared in step 3 is fixed at 45° downward in the precursor solution B prepared in step 4, and after mixing, it is placed in a reactor and subjected to a solvothermal reaction under nitrogen protection, the solvothermal reaction temperature is 150-200°C, the solvothermal reaction time is 12-20h, and after naturally cooling to room temperature, it is rinsed with deionized water and dried at a temperature of 80-100°C for 12-16h to obtain anatase phase TiO2 nanosheets on the FTO conductive glass substrate containing rutile phase TiO2 nanorods; Step 6: Surface fluorination treatment The anatase TiO2 nanosheets prepared in step 5 were heated to a concentration of 0.5x10 -2 -1x10 -2 After soaking in a mol / L NaF solution for 10-12 hours, the mixture was rinsed with deionized water, naturally air-dried, and then annealed in air at 300-400°C for 0.5-1 hour to obtain a rutile phase TiO2 nanorod / fluorine-doped anatase phase TiO2 nanosheet composite material.

3. The rutile phase TiO2 nanorod / fluorine-doped anatase phase TiO2 nanosheet composite material according to claim 1, characterized in that: The rutile phase TiO2 nanorod / fluorine-doped anatase phase TiO2 nanosheet composite material can achieve independent and selective optical transmittance modulation of visible light and near-infrared light at a voltage of +1.5V to -1.5V.

4. The rutile phase TiO2 nanorod / fluorine-doped anatase phase TiO2 nanosheet composite material according to claim 1, characterized in that: The rutile phase TiO2 nanorod / fluorine-doped anatase phase TiO2 nanosheet composite material has a contrast ratio of 57.2-70% in the 700nm band, a contrast ratio of 50.3-63.8% in the 1300nm band, a coloring time of 22.1-31.1s in the 700nm band, and a fading time of 8.0-9.3s.

5. The rutile phase TiO2 nanorod / fluorine-doped anatase phase TiO2 nanosheet composite material according to claim 1, characterized in that: The rutile phase TiO2 nanorods / fluorine-doped anatase phase TiO2 nanosheets composite material can provide three different sunlight adjustment modes, namely a bright mode that supports the transmission of visible light and near-infrared light, a cool mode that blocks near-infrared light and supports the transmission of visible light, and a dark mode that isolates near-infrared light and visible light transmittance.

6. The rutile phase TiO2 nanorod / fluorine-doped anatase phase TiO2 nanosheet composite material according to claim 1, characterized in that: After 2000 cycles of coloring and fading, the optical modulation amplitude of the rutile phase TiO2 nanorod / fluorine-doped anatase phase TiO2 nanosheet composite material in the 700nm band remains unchanged, and the optical modulation amplitude in the 1300nm band decreases by 16.7%.

7. Use of the rutile phase TiO2 nanorods / fluorine-doped anatase phase TiO2 nanosheet composite material according to any one of claims 1 to 6 as an electrochromic smart window.

8. A method for preparing a rutile phase TiO2 nanorod / fluorine-doped anatase phase TiO2 nanosheet composite material, characterized in that: The method comprises: Step 1: Pretreatment of FTO conductive glass substrate The FTO conductive glass substrate was placed in acetone, ethanol and deionized water in turn, and ultrasonically cleaned for 15 min respectively, and then dried with nitrogen to obtain a pretreated FTO conductive glass substrate; Step 2: Preparation of precursor solution A Tetrabutyl titanate and 12 mol / L concentrated hydrochloric acid are added to deionized water according to a ratio, wherein the volumes of tetrabutyl titanate, concentrated hydrochloric acid and deionized water are 2-3 mL, 10-15 mL and 15 ml, respectively, and a precursor solution A is obtained after stirring; Step 3: Preparation of rutile phase TiO2 nanorods The conductive surface of the FTO conductive glass substrate pretreated in step 1 is fixed at 45° downward in the precursor solution A prepared in step 2 for hydrothermal reaction at a temperature of 140-150°C for 3-4 hours. After naturally cooling to room temperature, the substrate is rinsed with deionized water and dried in air at 80°C for 12 hours. Finally, the substrate is annealed in air at 450°C for 0.5-1 hour to obtain rutile phase TiO2 nanorods on the FTO conductive glass substrate. Step 4: Preparation of precursor solution B Tetrabutyl titanate, triethanolamine and hydrofluoric acid are added to n-butanol according to a ratio, wherein the contents of tetrabutyl titanate, triethanolamine, hydrofluoric acid and n-butanol are 160-320 μL, 5-15 mL, 160-320 μL and 15 mL, respectively, and a precursor solution B is obtained after stirring; Step 5: Preparation of anatase phase TiO2 nanosheets The conductive surface of the FTO conductive glass substrate with rutile phase TiO2 nanorods prepared in step 3 is fixed at 45° downward in the precursor solution B prepared in step 4, and after mixing, it is placed in a reactor and subjected to a solvothermal reaction under nitrogen protection, the solvothermal reaction temperature is 150-200°C, the solvothermal reaction time is 12-20h, and after naturally cooling to room temperature, it is rinsed with deionized water and dried at a temperature of 80-100°C for 12-16h to obtain anatase phase TiO2 nanosheets on the FTO conductive glass substrate containing rutile phase TiO2 nanorods; Step 6: Surface fluorination treatment The anatase TiO2 nanosheets prepared in step 5 were heated to a concentration of 0.5x10 -2 -1x10 -2 After soaking in a mol / L NaF solution for 10-12 hours, the mixture was rinsed with deionized water, naturally air-dried, and then annealed in air at 300-400°C for 0.5-1 hour to obtain a rutile phase TiO2 nanorod / fluorine-doped anatase phase TiO2 nanosheet composite material.

9. Application of the preparation method of the rutile phase TiO2 nanorods / fluorine-doped anatase phase TiO2 nanosheet composite material according to claim 8 in the electrochromic smart window industry.

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