A titanium-based metal-organic framework and its preparation method and application

Abstract

The present invention belongs to the technical field of optoelectronic material preparation. Specifically disclosed is a titanium-based metal-organic framework and its preparation method and application. The titanium-based metal-organic framework Ti-HHTP disclosed by the present invention has a uniform morphology with a size of about 200 nm. The preparation method of the titanium-based metal-organic framework Ti-HHTP disclosed by the present invention is simple and can be completed within a short time by the solvothermal method. By means of noble metal assistance, regulating the solvent ratio and temperature, the complete conversion of Ti3C2 nanosheets into Ti-HHTP can be achieved under the conditions of DMF:H2O = 4.5:1 and 120 °C. Using the titanium-based metal-organic framework disclosed by the present invention as the active material for preparing an optoelectrode to prepare an optoelectrode, the preparation process is simple, can be completed at normal temperature and pressure, and the prepared optoelectrode has good optoelectronic response in the visible light region.

Description

Technical Field

[0001] The invention belongs to the technical field of photoelectric material preparation, and specifically relates to a titanium-based metal organic framework and a preparation method thereof and application thereof in the photoelectric field. Background Art

[0002] In recent years, with the rapid development of the information age and optoelectronic technology, optoelectronic devices have provided unprecedented advantages for modern society. Equipment such as optoelectronic display, optical communication, photovoltaic cells, lighting, laser technology, and photoelectric detection are constantly increasing with market demand. The research and development of these optoelectronic devices urgently requires the development of optoelectronic materials that are highly compatible with them. Advanced optoelectronic materials are the foundation and forerunner of the development of the entire optoelectronic device, and have developed from bulk materials to new materials such as thin layers, ultra-thin layers, and nano-microstructures. At present, the most commonly used new material for manufacturing optoelectronic devices is mainly graphene, but its low photosensitivity limits the further improvement of optoelectronic devices. In order to solve this problem, it is necessary to design optoelectronic materials with ultra-fast response speed and high photosensitivity in a targeted manner.

[0003] Metal-organic frameworks (MOFs) are a class of crystalline porous materials with periodic network structures formed by organic ligands and metal ions or clusters through coordination bonds. They have the advantages of high porosity, large specific surface area, and adjustable structure and function. They have great application potential in catalysis, gas storage and separation, sensing, drug delivery, bioimaging, and photodetectors. The representative synthesis strategy of MOFs is based on the direct chemical coordination of organic ligand units with conventional soluble metal salts in homogeneous solutions. However, this method still has many disadvantages, such as side reactions and the generation of disordered impurities during the reaction. In addition, it is difficult to achieve controllable release of metal ions in easily hydrolyzed metal salts, resulting in uncontrollable crystallization nucleation and morphology of MOFs. In contrast, insoluble metal precursors (metals, metal oxides, metal hydroxides, and metal carbonates) can slowly release metal ions to achieve controllable preparation of MOFs. This method has the advantages of good cost-effectiveness, environmental friendliness, and controllable crystallization kinetics.

[0004] However, the metal ion release from insoluble metal precursors reported so far is via protons (H + ) etching. +) The limitations of etching, see the open literature [Nguyen NTT, Furukawa H, Gándara, Felipe, et al. Three-Dimensional Metal-Catecholate Frameworks and Their Ultrahigh Proton Conductivity [J]. Journal of the American Chemical Society, 2015: 15394-15397] The reported insoluble metal precursors and organic ligands are mainly concentrated on acid-intolerant metal precursors and carboxylic acid ligands, the synthesis time is long and the prepared MOFs have uneven morphology, which limits the structural and functional expansion of MOFs.

[0005] As a class of two-dimensional 2D transition metal carbides, nitrides and carbonitrides, MXene is mainly prepared by etching the Al layer with hydrofluoric acid HF, which gives MXene abundant high electronegativity terminal atoms such as -F, -O and -OH, large specific surface area and atomic layer thickness. At the same time, the electronegativity difference between metal and carbon atoms leads to a higher lattice enthalpy of MXene than oxides and hydroxides, which makes MXene more chemically reactive. Based on this, MXene is expected to become an acid-resistant metal precursor for the preparation of MOFs. However, the use of metal ion-assisted strategies for 2D MXene-derived MOFs with adjustable conversion components has not been achieved so far. Summary of the invention

[0006] The purpose of the present invention is to provide a preparation of a titanium-based metal organic framework Ti-HHTP, and to prepare it into a photoelectrode. The present invention adopts noble metal ions such as [AuCl4]- to assist the conversion of Ti3C2 nanosheets and coordinates with HHTP to synthesize the titanium-based metal organic framework Ti-HHTP; compared with the original method of synthesizing Ti-MOF, the present invention can achieve the conversion of Ti3C2 in a short time by regulating the solvent ratio and temperature of DMF and H2O with the assistance of noble metal ions, and the converted Ti-HHTP has a uniform morphology. The converted Ti-HHTP is constructed into a photoelectrode by spin coating to achieve the preparation of the Ti-HHTP photoelectrode.

[0007] Technical solution:

[0008] In a first aspect, the present invention provides a titanium-based metal organic framework, such as Fig.11 As shown, the titanium-based metal organic framework is prepared by completely converting ultrathin Ti3C2 nanosheets into a titanium-based metal organic framework Ti-HHTP under the auxiliary induction of noble metal ions and controlling the solvent ratio and reaction temperature. The prepared Ti-HHTP has a uniform morphology and a size of about 200 nm.

[0009] The solvent is a mixed solvent of DMF and H2O, wherein the volume ratio of DMF to H2O is 4.5:1;

[0010] The reaction temperature is 120°C;

[0011] The noble metal ion is [AuCl4] - 、Ag + and [PtCl6] 2- Any of the following;

[0012] The ultrathin Ti3C2 nanosheets are two-dimensional sheet structures prepared by solvothermal method and ultrasonic exfoliation method, with a size of 400-500nm;

[0013] The mass ratio of the added amount of the ultra-thin Ti3C2 nanosheets to the added amount of the precious metal is 1:2.

[0014] The present invention also provides a preferred preparation method of the titanium-based metal organic framework, which comprises the following steps:

[0015] Step S1: add 7.5 mg mL -1 The ultrathin Ti3C2 nanosheet solution is centrifuged at a speed of 10000rpm to 12000rpm for 10-15min, the supernatant is discarded, and the bottom precipitate is taken and a mixed solvent is added to form a uniform solution by ultrasound, wherein the volume ratio of the ultrathin Ti3C2 nanosheet solution to the mixed solvent is 2:15; the mixed solvent is a mixture of DMF and H2O and the volume ratio is DMF:H2O=4.5:1;

[0016] Step S2, adding noble metal ions under stirring conditions of the homogeneous solution, stirring evenly, adding HHTP solution, stirring evenly, heating to 120°C and reacting for 4 hours, wherein the noble metal ions include [AuCl4]-, Ag + and [PtCl6] 2- ; The mass ratio of the added amount of the ultra-thin Ti3C2 nanosheets to the added amount of the precious metal is 1:2, and the mass ratio of the added amount of the ultra-thin Ti3C2 nanosheets to the added amount of the HHTP is 1:4;

[0017] Step S3, after cooling to room temperature, washing with ethanol for 3-5 times, then transferring the centrifuge tube to a vacuum drying oven and drying for 12-14 hours to obtain the product titanium-based metal organic framework Ti-HHTP.

[0018] Preferably, the preparation steps of the ultrathin Ti3C2 nanosheets are as follows: 9M hydrochloric acid is added to the reactor, LiF is added to the reactor under stirring, Ti3AlC2 is added under stirring, and stirred for 20 to 30 minutes, and then the reactor is transferred to a blast drying oven at 60°C for reaction for 24 hours; wherein the volume mass ratio of hydrochloric acid to LiF is 10mL:0.5g; the mass ratio of LiF to Ti3AlC2 is 1:1; after the reaction is completed, the product in the reactor is washed with deionized water for 5 to 7 times and ethanol for 1 time. The multilayer Ti3C2 nanosheets were dissolved in H2O and dispersed evenly, and Ar was exhausted for 15 to 20 minutes. The product was ultrasonically treated for 1 hour and transferred to a 50 mL centrifuge tube at a speed of 3500 rpm for 1 hour. The bottom precipitate was discarded and the upper solution was reserved for later use to obtain the prepared ultrathin Ti3C2 nanosheets u-Ti3C2. The mass volume ratio of the multilayer Ti3C2 nanosheets to H2O was 75 mg:10 mL.

[0019] In a second aspect, the present invention provides the use of the titanium-based metal organic framework Ti-HHTP as a photoelectric electrode active material, that is, provides a photoelectric electrode based on Ti-HHTP.

[0020] The preparation method of the photoelectrode based on Ti-HHTP comprises the following steps: taking the above Ti-HHTP as an active material, adding ethanol and Nafion solution, ultrasonically dispersing it uniformly as an electrode solution, taking the electrode solution and spin coating it on ITO glass and standing it to dry, the spin coating thickness ranges from 50nm to 100nm;

[0021] Preferably, the mass volume ratio of the Ti-HHTP active material to ethanol is 2 mg:1 mL;

[0022] Preferably, the volume ratio of the ethanol to the Nafion solution is 100:1.

[0023] Beneficial effects:

[0024] The present application adopts precious metal ions to assist the conversion of two-dimensional Ti3C2 nanosheets into titanium-based metal organic framework Ti-HHTP. Compared with the original method of synthesizing Ti-MOF in the prior art, the present invention can achieve the conversion of Ti3C2 in a short time by regulating the ratio of DMF and H2O in the mixed solvent and the reaction temperature with the assistance of precious metal ions, and the converted Ti-HHTP has a uniform morphology.

[0025] The converted titanium-based metal organic framework Ti-HHTP was constructed into a photoelectrode by spin coating. The preparation process of Ti-HHTP photoelectrode is simple and can be completed at room temperature and pressure. It has been verified by assembling three electrodes and the power density is 300mW cm in the visible light region. -2 , 200mW cm -2 and 100 mW cm -2 The photoelectric response test was carried out under the conditions of , and the test results showed that the photoelectric electrode made based on the titanium-based metal organic framework of the present invention has a good photoelectric response in the visible light region and can be used as a detection part of a visible light photoelectric device. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a SEM photo of the multilayer Ti3C2 nanosheet prepared in Example 1;

[0027] Figure 2 XRD spectrum of multilayer Ti3C2 nanosheets prepared in Example 1;

[0028] Figure 3 TEM image of the ultrathin Ti3C2 nanosheet prepared in Example 2;

[0029] Figure 4 This is a SEM image of the titanium-based metal organic framework Ti-HHTP prepared in Example 3;

[0030] Figure 5 This is a TEM image of the titanium-based metal organic framework Ti-HHTP prepared in Example 3;

[0031] Figure 6 XRD spectrum of the titanium-based metal organic framework Ti-HHTP prepared in Example 3;

[0032] Figure 7 The full XPS spectrum of the titanium-based metal organic framework Ti-HHTP prepared in Example 3;

[0033] Figure 8 XPS Ti 2p spectrum of the titanium-based metal-organic framework Ti-HHTP prepared in Example 3;

[0034] Fig. 9 This is the UV-visible absorption spectrum of the titanium-based metal organic framework Ti-HHTP prepared in Example 3;

[0035] Fig.10 Photoelectric response spectrum in Test Example 3;

[0036] Fig.11 This is a schematic diagram of the preparation process of the titanium-based metal organic framework of the present invention. DETAILED DESCRIPTION

[0037] The following examples further illustrate the content of the present invention, but should not be construed as limiting the present invention. Without departing from the essence of the present invention, modifications and substitutions made to the methods, steps or conditions of the present invention all fall within the scope of the present invention.

[0038] Meanwhile, the raw materials or reagents mentioned below that are not described in detail are all commercially available products, and the process steps or methods that are not described in detail are all process steps or methods known to those skilled in the art.

[0039] The sources of some raw materials and reagents involved in the following embodiments and test examples are as follows:

[0040] Drugs and reagents Specification supplier Carbon Aluminum Titanium 99.99％ Jilin Yiyi Technology Co., Ltd. Lithium fluoride 98％ Shanghai Aladdin Biochemical Technology Co., Ltd. Concentrated hydrochloric acid AR Shanghai Lingfeng Chemical Reagent Co., Ltd. Chloroauric acid Tianjin Guangfu Fine Chemical Research Institute Hexahydroxytriphenylene 98％ Shanghai Tengqian Biotechnology Co., Ltd. N,N-Dimethylformamide AR Sinopharm Chemical Reagent Co., Ltd. Ethanol AR Wuxi Yasheng Chemical Co., Ltd. Concentrated sulfuric acid AR Shanghai Lingfeng Chemical Reagent Co., Ltd. Potassium chloride AR Sinopharm Chemical Reagent Co., Ltd.

[0041] Example 1: Preparation of multilayer Ti3C2 nanosheets

[0042] Add 10mL 9M hydrochloric acid to the reactor, add 0.5g LiF to the reactor under stirring, add 0.5g Ti3AlC2 under stirring, stir for 20-30min, and then transfer the reactor to a forced air drying oven for reaction at 60°C for 24h. After the reaction, transfer the product in the reactor to a 50mL centrifuge tube, wash with deionized water 5-7 times, wash with ethanol once, and then transfer the centrifuge tube to a vacuum drying oven for drying for 12-14h to obtain the prepared multilayer Ti3C2 nanosheets.

[0043] like Figure 1 As shown in Figure 2, the multilayer Ti3C2 nanosheets obtained by etching the Al layer with HF generated by LiF and HCl exhibit an accordion structure with a size of about 4-5 μm. Figure 2 As shown, the multilayer Ti3C2 nanosheets have a characteristic diffraction peak corresponding to the (002) crystal plane at 2θ=6.22°, which is consistent with that reported in the literature, indicating that the multilayer Ti3C2 nanosheets were successfully prepared.

[0044] Example 2: Preparation of ultrathin Ti3C2 nanosheets

[0045] Weigh 75 mg of multilayer Ti3C2 nanosheets and dissolve them in 10 mL of H2O to disperse them evenly. Exhaust Ar for 15-20 min, ultrasonically treat for 1 h, transfer them to a 50 mL centrifuge tube, rotate at 3500 rpm, centrifuge for 1 h, discard the bottom precipitate, and keep the upper solution for use, which is the prepared ultrathin Ti3C2 nanosheets.

[0046] like Figure 3 As shown, the ultrathin Ti3C2 nanosheets exhibit a two-dimensional sheet structure with a size of about 400-500nm.

[0047] Example 3: Preparation of titanium-based metal organic framework Ti-HHTP

[0048] Prepare [AuCl4]- solution: weigh 0.31 g HAuCl44H2O and dissolve it in 0.25 mL H2O, and ultrasonicate to form a uniform solution; prepare HHTP solution: weigh 65 mg HHTP and dissolve it in 4 mL DMF solution, and ultrasonicate to form a uniform solution.

[0049] Preparation steps: Take 2mL 7.5mg mL -1 The Ti3C2 solution was placed in a 15mL centrifuge tube and centrifuged at a speed of 1000-1200rpm for 10-15min. The supernatant was discarded and the bottom precipitate was taken. Then, 11mL DMF / H2O (DMF:H2O=4.5:1) was added to the 15mL centrifuge tube, and ultrasonication was used to form a uniform solution, and the solution was transferred to a 25mL eggplant-shaped bottle; 25μL HAuCl44H2O (30.89mg, 0.075mmol) was added under stirring conditions and stirred evenly. Then, 4mL HHTP solution was added and stirred evenly, and then transferred to an oil pan and heated to 120℃ for reaction for 4h; after cooling to room temperature, it was washed with ethanol 3-5 times, and then the centrifuge tube was transferred to a vacuum drying oven for drying for 12-14h. Figure 4 The SEM image of the titanium-based metal organic framework Ti-HHTP after centrifugal washing is shown. Figure 5 The TEM morphology is shown, and it can be seen that the size of the Ti-HHTP prepared in Example 3 is about 200 nm, the morphology is uniform, and it presents a solid structure.

[0050] like Figure 6 As shown, the XRD spectrum of Ti-HHTP prepared in Example 3 is consistent with the XRD spectrum of Ti-CAT-5 reported in the literature [Nguyen NTT, Furukawa H, Gándara, Felipe, et al. Three-Dimensional Metal-Catecholate Frameworks and Their Ultrahigh Proton Conductivity [J]. Journal of the American Chemical Society, 2015: 15394-15397]. Figure 1 The results show that the titanium-based metal-organic framework Ti-HHTP was prepared by [AuCl4]-induced transformation of Ti3C2 nanosheets.

[0051] Test Example 1: XPS test of titanium-based metal-organic framework Ti-HHTP

[0052] Place Ti-HHTP powder on the conductive glue, stick the conductive glue on the XPS sample stage, and then put the sample stage into the XPS test chamber for testing.

[0053] like Figure 7 As shown, the XPS spectrum of Ti-HHTP shows that it contains C, O and Ti elements.

[0054] like Figure 8 As shown in the Ti 2p spectrum, the Ti 2p 3 / 2 and the characteristic peak of Ti 2p at 464.1 eV 1 / 2 The characteristic peaks are attributed to Ti 4+ This indicates that the Ti atom exists as +4 titanium oxide in the titanium-based metal-organic framework Ti-HHTP, which further indicates that Ti3C2 is completely converted into Ti-HHTP.

[0055] Test Example 2: UV-visible absorption spectrum test of titanium-based metal organic framework Ti-HHTP

[0056] Take the titanium-based metal organic framework Ti-HHTP powder and place it in the center of the BaSO4 powder, flatten it, and put it into the ultraviolet absorption instrument for testing.

[0057] like Fig. 9 As shown, the UV-visible absorption spectrum shows that the titanium-based metal-organic framework Ti-HHTP has good absorption ability in the visible light region.

[0058] Example 4: Preparation of Ti-HHTP photoelectrode

[0059] Weigh 2 mg of Ti-HHTP powder and place it in a 5 mL centrifuge tube. Add 1 mL of ethanol and 10 μL of Nafion solution. Ultrasound (50 W 40 kHz) was applied for 30 min. 160 μL of the above solution was spin-coated on ITO glass and allowed to dry before use for the photoelectric response test of Ti-HHTP.

[0060] Test Example 3: Photoelectric response test of titanium-based metal organic framework Ti-HHTP

[0061] Weigh 2.84g of solid Na2SO4 into a beaker, add deionized water to dissolve it, and then transfer it to a volumetric flask as the electrolyte solution; use the Ag / AgCl electrode as the reference electrode, the Pt sheet electrode (1cm×1cm) as the counter electrode, and the ITO glass electrode as the working electrode. The wavelength range is the visible light region, and the power density is 300, 200, and 100mW cm -2 The photoelectric response test was carried out under the conditions to further study its photoelectric properties.

[0062] like Fig.10As shown, at different intensities of 300 mW cm -2 , 200mW cm -2 and 100 mW cm -2 Under light irradiation, the titanium-based metal organic framework Ti-HHTP has a good photoelectric response in the visible light region, and the photocurrent density can reach 2.25 μA cm -2 .

Claims

1. A titanium-based metal-organic framework, characterized in that: The titanium-based metal organic framework is completely transformed from ultrathin Ti3C2 nanosheets and HHTP under the auxiliary induction of noble metal ions by controlling the solvent ratio and reaction temperature. The solvent is a mixed solvent of DMF and H2O, wherein the volume ratio of DMF to H2O is 4.5:1; the reaction temperature is 120°C; the noble metal ion is [AuCl4] - 、Ag + or [PtCl6] 2- Any one of the above; the ultra-thin Ti3C2 nanosheets are two-dimensional sheet structures prepared by solvothermal method and ultrasonic exfoliation method, with a size of 400-500 nm; the mass ratio of the addition amount of the ultra-thin Ti3C2 nanosheets to the addition amount of the precious metal is 1:

2.

2. The method for preparing the titanium-based metal organic framework according to claim 1, characterized in that: The preparation method comprises the following steps: Step S1: add 7.5 mg mL -1 The ultrathin Ti3C2 nanosheet solution is centrifuged at a speed of 10000 rpm to 12000 rpm for 10-15 min, the supernatant is discarded, and the bottom precipitate is taken and a mixed solvent is added to form a uniform solution by ultrasound, wherein the volume ratio of the ultrathin Ti3C2 nanosheet solution to the mixed solvent is 2:15; Step S2, adding noble metal ions under stirring conditions of the homogeneous solution, adding HHTP solution after stirring, heating to 120° C. and reacting for 4 h; the mass ratio of the added amount of the ultrathin Ti3C2 nanosheets to the added amount of the HHTP is 1:4; Step S3, after cooling to room temperature, washing with ethanol for 3-5 times, then transferring the centrifuge tube to a vacuum drying oven and drying for 12-14 h to obtain the product titanium-based metal organic framework Ti-HHTP.

3. The preparation method according to claim 2, characterized in that: The preparation steps of the ultrathin Ti3C2 nanosheets include: adding 9 M hydrochloric acid to a reactor, adding LiF to the reactor under stirring conditions, adding Ti3AlC2 under stirring conditions, stirring for 20-30 min, and then transferring the reactor to a forced air drying oven for reaction at 60°C for 24 h; wherein the volume mass ratio of hydrochloric acid to LiF is 10 mL:0.5 g; the mass ratio of LiF to Ti3AlC2 is 1:1; after the reaction is completed, the product in the reactor is washed with deionized water for 5-7 times, washed with ethanol once, and then transferred to a vacuum drying oven for drying for 12-14 h, thereby obtaining the prepared multilayer Ti3C2 nanosheets m-Ti3C2; the multilayer Ti3C2 nanosheets are dissolved in H2O and dispersed evenly, Ar is exhausted for 15-20 min, ultrasonic treatment is performed for 1 h, and then transferred to a 50 mL centrifuge tube at a speed of 3500 rpm and centrifuged for 1 h, discard the bottom precipitate, and keep the upper solution for use, which is the prepared ultrathin Ti3C2 nanosheet u-Ti3C2; wherein the mass volume ratio of the multilayer Ti3C2 nanosheet to H2O is 75 mg:10 mL.

4. Use of the titanium-based metal organic framework according to claim 1 as a photoelectric electrode active material.

5. The use according to claim 4, characterized in that: The application comprises the steps of: taking the titanium-based metal organic framework as an active material, adding ethanol and Nafion solution, ultrasonically dispersing it evenly as an electrode solution, taking the electrode solution and spin coating it on ITO glass, standing it to dry, the spin coating thickness range is 50 nm to 100 nm, and preparing a photoelectric electrode based on the titanium-based metal organic framework.

6. The use according to claim 5, characterized in that: The mass volume ratio of the titanium-based metal organic framework to ethanol is 2 mg:1 mL.

7. The use according to claim 5, characterized in that: The volume ratio of the ethanol to the Nafion solution is 100:1.

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