阅读说明：本技术 一种利用超临界二氧化碳制备TiO2/COF催化材料的方法 (Method for preparing TiO by using supercritical carbon dioxide2Method for preparing/COF catalytic material ) 是由 刘力菲 张建玲 石金彪 张丙兴 陈刚 杨冠英 于 2019-09-04 设计创作，主要内容包括：本发明公开了一种利用超临界二氧化碳制备TiO_2/COF催化材料的方法。该方法利用超临界二氧化碳极佳的分散性,将TiO_2纳米颗粒均匀地负载在TbBd-COF空心球内外表面。此外,超临界二氧化碳的合理应用促进了TiO_2与COF之间Ti-N键的形成,从而有效构建了TiO_2/COF异质结,促进光生电荷的转移与分离,提高电荷利用效率,实现了高效可见光催化产氢。本发明首次利用超临界二氧化碳实现了TiO_2/COF空心球异质结光催化材料的调控合成,为新型光催化剂的制备提供了一种环境友好的新方法。(The invention discloses a method for preparing TiO by using supercritical carbon dioxide 2 Method of/COF catalytic material. The method utilizes the excellent dispersibility of supercritical carbon dioxide to prepare TiO 2 The nano-particles are uniformly loaded on TbBd-COF hollow sphere inner and outer surfaces. In addition, the rational use of supercritical carbon dioxide promotes TiO 2 And the formation of a Ti-N bond with COF, thereby effectively constructing TiO 2 the/COF heterojunction promotes the transfer and separation of photo-generated charges, improves the charge utilization efficiency and realizes efficient visible light catalytic hydrogen production. The invention realizes the TiO formation by using the supercritical carbon dioxide for the first time 2 The controlled synthesis of the/COF hollow sphere heterojunction photocatalytic material provides a novel environment-friendly method for preparing a novel photocatalyst.)

1. A COF material formed by connecting the repeating structural units shown in the formula I by covalent bonds, namely TbBd-COF,

in the formula I, the compound has the following structure,representing the substituted bit.

2. A method of making the TbBd-COF of claim 1, comprising: and uniformly mixing trimesic aldehyde and biphenyldiamine in a solvent to perform an amine-aldehyde condensation reaction, and obtaining the TbBd-COF after the reaction is finished.

3. The method of claim 2, wherein: the feeding molar ratio of the trimesic aldehyde to the biphenyldiamine is 0.9: 1-1.5; specifically 0.9: 1.35;

the solvent is a mixed solution consisting of dioxane and an acetic acid aqueous solution; the volume ratio of the dioxane to the acetic acid aqueous solution is 50: 9;

the dosage ratio of the trimesic aldehyde to the dioxane is 0.9 mmol: 10 mL;

in the step of amine-aldehyde condensation reaction, the temperature is 100-150 ℃; in particular to 120 ℃; the time period required was 72 hours.

4. Use of the TbBd-COF of claim 1 in the preparation of TiO₂The application of the/COF photocatalysis material;

use of the TbBd-COF of claim 1 in combination with supercritical carbon dioxide in the preparation of TiO₂Application in/COF photocatalytic materials.

5. TiO 2₂/COF photocatalytic material made of TiO₂Nanoparticles and the TbBd-COF of claim 1;

the TiO is₂Nanoparticles are uniformly dispersed on the inner and outer surfaces of the TbBd-COF.

6. A photocatalytic composition comprising the TiO of claim 5₂a/COF photocatalytic material and noble metal nanoparticles.

7. A process for preparing the TiO of claim 5₂A method of/COF photocatalytic material comprising: taking tetrabutyl titanate (TBT), water, ethanol and the TbBd-COF of claim 1 as raw materials, carrying out hydrolysis reaction in the presence of supercritical carbon dioxide, and obtaining the TiO after the reaction is finished₂a/COF photocatalytic material.

8. The method of claim 7, wherein: the mass ratio of the TBT to the TbBd-COF is 1: 1-2;

in the hydrolysis reaction step, the temperature is 100-150 ℃; in particular to 120 ℃;

the pressure of the supercritical carbon dioxide is 0-5.52 MPa;

the time is 12-24 h.

9. The TiO of claim 5₂Use of a/COF photocatalytic material or a photocatalytic composition according to claim 6 as a catalyst in photocatalysis.

10. The photocatalytic composition according to claim 6 or the use according to claim 9, characterized in that: the photocatalysis is photocatalytic water cracking reaction; in particular to a visible light catalytic water cracking reaction; the visible light is visible light with the wavelength of 380nm-780 nm;

the noble metal nanoparticles are Pt or Au nanoparticles;

in the photocatalysis, the reaction time is 4-12 h; the temperature is normal temperature; specifically 25 ℃.

Technical Field

The invention belongs to the field of materials, and relates to a method for preparing TiO by using supercritical carbon dioxide₂Method of/COF catalytic material.

Background

The development and utilization of renewable energy is an important issue facing mankind. Solar energy is a novel renewable energy source, and is favored by various social circles due to the characteristics of inexhaustibility, environmental protection and the like. Therefore, the conversion, storage and utilization of solar energy to chemical energy becomes very important. TiO 2₂As the first discovered photocatalytic material, extensive research and report have been made so far. In 1972, Fujishima and Honda first proposed TiO₂The catalyst has the photoelectrocatalysis hydrogen production activity, thus opening the door for direct conversion and utilization from solar energy to hydrogen energy. In recent years, TiO₂The catalyst has the advantages of no toxicity, low price, easy obtainment, chemical stability, high catalytic activity and the like, and is widely concerned. But TiO is due to its broader band (3.0-3.2eV)₂Can only absorb ultraviolet light (<380nm) and hardly responds to the visible region accounting for 43% of the total solar energy. In addition, the rapid recombination of photo-generated electrons and holes and the extremely low quantum efficiency in the visible region hinder the improvement of the conversion efficiency from solar energy to hydrogen energy. Therefore, how to realize the efficient conversion from visible light energy to chemical energy is a problem to be solved in the field of photocatalysis at present. The current solutions focus mainly on shrinking TiO₂The band gap is used for promoting the visible light absorption, and the specific method comprises the following steps: complexing with semiconductors, heteroatom doping, metal deposition and conditioning of TiO₂The microstructure of (a). TiO 2₂The compound with a semiconductor with proper energy level can realize the effective transfer and separation of photo-generated charges, and plays an important role in a plurality of methods for optimizing energy band structures. Relative to the applicationThe application of the inorganic semiconductor material and the organic semiconductor photocatalyst material with proper energy level is greatly limited. g-C most widely used therein₃N₄For example, its further applications are limited primarily by the relatively wide band gap and the single chemical structure.

Covalent Organic Framework (COF) materials are a new type of porous crystalline material formed by covalent bonding of non-metallic light elements. Since the first report by Yaghi in 2005, COF has been rapidly developed in the fields of gas adsorption and separation, energy storage, photoelectrocatalysis and the like. The large pi conjugated structure endows COF with excellent light absorption and electron transfer capacity. The regular crystal structure, the large specific surface area and the uniform pore size distribution all contribute to the transfer of photo-generated charges. In addition, the COF also has good physical and chemical stability. Based on the above advantages, the COF can be used as a substrate of the photocatalyst and further functionalized. Thus, COF was combined with TiO₂The combination of the heterojunction is expected to realize the high-efficiency conversion from solar energy to chemical energy.

Disclosure of Invention

The invention aims to provide a method for preparing TiO by using supercritical carbon dioxide₂The method of the/COF catalytic material is used for realizing high-efficiency visible light catalytic hydrogen production.

The invention claims a COF material formed by connecting the repeating structural units shown in the formula I by covalent bonds, namely TbBd-COF,

in the formula I, the compound has the following structure,representing the substituted bit.

The TbBd-COF is a hollow sphere in apparent form and is a porous crystal material.

The invention also claims a process for preparing the TbBd-COF, comprising: and uniformly mixing trimesic aldehyde and biphenyldiamine in a solvent to perform an amine-aldehyde condensation reaction, and obtaining the TbBd-COF after the reaction is finished.

In the method, the feeding molar ratio of the trimesic aldehyde to the biphenyldiamine is 0.9: 1-1.5; specifically 0.9: 1.35;

the solvent is a mixed solution consisting of dioxane and an acetic acid aqueous solution; the volume ratio of the dioxane to the acetic acid aqueous solution is 50: 9; the concentration of the acetic acid aqueous solution is specifically 3M;

the dosage ratio of the trimesic aldehyde to the dioxane is 0.9 mmol: 10 mL;

in the step of amine-aldehyde condensation reaction, the temperature is 100-150 ℃; in particular to 120 ℃; the time is 72 hours;

the amine-aldehyde condensation reaction is carried out in a reaction kettle; the inner lining of the reaction kettle is made of polytetrafluoroethylene.

In addition, the invention also claims the TbBd-COF in the preparation of TiO₂Application of/COF (polycrystalline cubic boron nitride) photocatalytic material and combination of TbBd-COF and supercritical carbon dioxide in preparation of TiO₂Application in/COF photocatalytic materials.

The TiO is₂/COF photocatalytic material made of TiO₂Nanoparticles and the TbBd-COF;

the TiO is₂Nanoparticles are uniformly dispersed on the inner and outer surfaces of the TbBd-COF.

The TiO is₂The particle size of the nano-particles is 5.6 +/-1.2 nm.

The invention also claims TiO₂/COF photocatalytic material made of TiO₂Nanoparticles and the TbBd-COF;

the TiO is₂Nanoparticles are uniformly dispersed on the inner and outer surfaces of the TbBd-COF.

The invention also claims a photocatalytic composition consisting of said TiO₂a/COF photocatalytic material and noble metal nanoparticles.

The noble metal nanoparticles are Pt or Au nanoparticles. The noble metal nanoparticles function as co-catalysts in the composition.

The invention also claims to prepare the TiO₂A method of/COF photocatalytic material, the method comprising: with tetrabutyl titanate (TBT), water, ethanol and the TbBd-COF are taken as raw materials, hydrolysis reaction is carried out in the presence of supercritical carbon dioxide, and the TiO is obtained after the reaction is finished₂a/COF photocatalytic material.

In the method, the mass ratio of the TBT to the TbBd-COF is 1: 1-2;

in the hydrolysis reaction step, the temperature is 100-150 ℃; in particular to 120 ℃;

the pressure of the supercritical carbon dioxide is 0-5.52 MPa;

the time is 12-24 h.

The method may further comprise: after the reaction is finished, cooling the reaction system to room temperature, slowly discharging gas, centrifugally separating the product, washing the product with ethanol for three times, and carrying out vacuum drying at 80 ℃ for 12 hours to obtain a yellow solid, namely the target product.

Further, the above TiO according to the present invention₂Application of/COF (chip on film) photocatalytic material as catalyst in photocatalysis and TiO₂The application of the composition consisting of the/COF photocatalytic material and the noble metal nano-particles as a catalyst in photocatalysis also belongs to the protection scope of the invention. Wherein the photocatalysis is photocatalytic water splitting reaction; in particular to a visible light catalytic water cracking reaction; the visible light is visible light with wavelength of 380nm-780 nm. The noble metal nanoparticles are Pt or Au nanoparticles. The noble metal nanoparticles function as co-catalysts in the composition.

In the photocatalysis, the reaction time is 4-12 h; the temperature is normal temperature; specifically 25 ℃.

Since energy problems have penetrated the aspects of human society, efficient conversion and utilization of solar energy are imminent. The invention utilizes the excellent dispersibility of the supercritical carbon dioxide to prepare TiO₂The nano-particles are uniformly loaded on the inner surface and the outer surface of the TbBd-COF hollow sphere. In addition, the rational use of supercritical carbon dioxide promotes TiO₂And the formation of a Ti-N bond with COF, thereby effectively constructing TiO₂the/COF heterojunction promotes the transfer and separation of photo-generated charges, improves the charge utilization efficiency and realizes efficient visible light catalytic hydrogen production. The invention provides the use of supercritical dioxygen for the first timeCarbon conversion to produce TiO₂The method of the/COF heterojunction photocatalyst realizes high-efficiency visible light catalytic hydrogen production. The method is mild in condition, simple and feasible, has a great development prospect when being applied to the preparation of other heterojunction photocatalysts, and is beneficial to the further development of the field of photocatalysis.

Drawings

FIG. 1 is TiO₂/TbBd-1、TiO₂@TbBd、TiO₂And the X-ray diffraction pattern of TbBd-COF.

FIG. 2 is TiO₂/TbBd-1、TiO₂@TbBd、TiO₂And the IR spectrum of TbBd-COF.

FIG. 3 is TiO₂/TbBd-1、TiO₂@TbBd、TiO₂And an X-ray photoelectron spectrum of TbBd-COF.

FIG. 4 is TiO₂/TbBd-1、TiO₂@TbBd、TiO₂And the ultraviolet-visible diffuse reflection spectrogram of TbBd-COF.

FIG. 5 is TiO₂(Black), TiO₂@ TbBd (blue) with TiO₂The total amount of hydrogen produced by the photocatalysis of the/TbBd-1 (red) at different reaction times.

FIG. 6 is TiO₂(Black), TiO₂@ TbBd (blue) with TiO₂The TOF value of hydrogen produced by photocatalysis at different reaction times by/TbBd-1 (red).

FIG. 7 is TiO₂After 12h of photocatalytic reaction of/TbBd-1 (Red) with simulated TiO₂XRD pattern of (black).

FIG. 8 is TiO₂TEM image after 12h of a/TbBd-1 photocatalytic reaction.

FIG. 9 is TiO₂/TbBd-1 (Red), TiO₂@ TbBd (blue), TiO₂Electrochemical impedance spectra of (black) and TbBd-COF (green).

FIG. 10 is TiO₂/TbBd-1 (Red), TiO₂@ TbBd (blue), TiO₂Photocurrent test curves for (black) and TbBd-COF (green).

FIG. 11 is TiO₂/TbBd-1 (Red), TiO₂@ TbBd (blue), TiO₂Photoluminescence emission spectra of (black) and TbBd-COF (green).

FIG. 12 is a schematic diagram of the preparation of TbBd-COF.

FIG. 13 is a diagram showing the energy level changes before and after the synthesis of TbBd-COF.

Detailed Description

The present invention will be further illustrated with reference to the following specific examples, but the present invention is not limited to the following examples. The method is a conventional method unless otherwise specified. The starting materials are commercially available from the open literature unless otherwise specified.