阅读说明：本技术 窄禁带低价带改性TiO2光催化剂的制备方法 (Narrow forbidden band low valence band modified TiO2Method for preparing photocatalyst ) 是由 刘聚明 庞少华 程琳 马惠言 张前程 于 2020-07-30 设计创作，主要内容包括：本发明公开了窄禁带低价带改性TiO<Sub>2</Sub>光催化剂的制备方法,在TiO<Sub>2</Sub>合成过程中或在TiO<Sub>2</Sub>合成后,加入含具有吸电子特性的配体的前驱物,利用具有吸电子特性的配体与TiO<Sub>2</Sub>进行表面、界面和/或晶格间隙的配合,从微观上改变TiO<Sub>2</Sub>晶格中Ti和O周围的电子环境,诱导O p轨道能级和Ti d轨道能级同步降低,构建窄禁带低价带改性TiO<Sub>2</Sub>光催化剂。一方面达到缩减TiO<Sub>2</Sub>禁带宽度的目的,以扩展光催化剂的可见光响应范围,提高光催化效率；另一方面,在缩减禁带宽度的同时保持或者降低TiO<Sub>2</Sub>价带位置,使光生空穴具有较强的氧化能力,增强光催化氧化性能。(The invention discloses a narrow forbidden band low valence band modified TiO 2 Method for preparing photocatalyst on TiO 2 During synthesis or in TiO 2 After synthesis, a precursor containing a ligand with electron-withdrawing property is added, and the ligand with electron-withdrawing property and TiO are utilized 2 The surface, interface and/or lattice gap matching is carried out to change the TiO from the micro 2 The electronic environment around Ti and O in the crystal lattice induces O p orbital energy level and Ti d orbital energy level to be synchronously reduced, and the narrow forbidden band low-valence band modified TiO is constructed 2 A photocatalyst. On the one hand, the reduction of TiO is achieved 2 The purpose of forbidden bandwidth is to expand the visible light response range of the photocatalyst and improve the photocatalytic efficiency; on the other hand, the forbidden band width is reduced while the TiO is kept or reduced 2 Valence band position, photohole generating toolHas stronger oxidizing power and enhances the photocatalytic oxidizing performance.)

1. Narrow forbidden band low valence band modified TiO₂The preparation method of the photocatalyst is characterized in that the photocatalyst is prepared from TiO₂During synthesis or in TiO₂After synthesis, a precursor containing a ligand with electron-withdrawing property is added, and the ligand with electron-withdrawing property and TiO are utilized₂The surface, interface and/or lattice gap matching is carried out to change the TiO from the micro₂The electronic environment around Ti and O in the crystal lattice induces O p orbital energy level and Ti d orbital energy level to be synchronously reduced, and the narrow forbidden band low-valence band modified TiO is constructed₂A photocatalyst.

2. The narrow forbidden band low valence band modified TiO of claim 1₂The preparation method of the photocatalyst is characterized in that the TiO is₂The synthesis method of (a) is any one of a sol-gel method, a hydrothermal method or a solvothermal method.

3. The narrow forbidden band low valence band modified TiO of claim 2₂The preparation method of the photocatalyst is characterized in that the ligand with the electron withdrawing characteristic is an electron withdrawing atom or an electron withdrawing group.

4. The narrow forbidden band low valence band modified TiO of claim 3₂The preparation method of the photocatalyst is characterized in that the electron-withdrawing atom is any one or the combination of more than one of fluorine atom, chlorine atom or bromine atom.

5. The narrow forbidden band low valence band modified TiO of claim 4₂A method for producing a photocatalyst, characterized in that the electron-withdrawing atom is a fluorine atom and is present in TiO₂When the method is introduced in the synthesis process, the method comprises the following steps:

(1) mixing tetrabutyl titanate, 40 wt% hydrofluoric acid solution and distilled water at room temperature, and continuously stirring for more than 1h to prepare mixed solution; wherein the volume ratio of tetrabutyl titanate to 40 wt% hydrofluoric acid solution to distilled water is as follows: 30: 3.83: 5;

(2) transferring the mixed solution into a reaction kettle with a polytetrafluoroethylene lining, and carrying out hydrothermal reaction for 12-24h at the temperature of 150-;

(3) after the hydrothermal reaction is finished, separating the solid product, fully washing the solid product with distilled water and absolute ethyl alcohol, and drying the solid product at the temperature of 80 ℃ for more than 12 hours to prepare a solid material;

(4) carrying out heat treatment on the solid material at 300 ℃ for 2-4h to obtain the fluorine-containing narrow forbidden band low-valence band modified TiO₂And (5) obtaining a finished product of the photocatalyst.

6. The narrow forbidden band low valence band modified TiO of claim 3₂The preparation method of the photocatalyst is characterized in that the electron-withdrawing group is any one or the combination of more than one of carboxyl, carbonyl, nitro or sulfonic acid.

7. The narrow forbidden band low valence band modified TiO of claim 6₂The preparation method of the photocatalyst is characterized in that the electron-withdrawing group is carboxyl and is in TiO₂When the method is introduced in the synthesis process, the method comprises the following steps:

(1) taking absolute ethyl alcohol, glacial acetic acid and distilled water, and uniformly mixing to obtain a solution A, wherein the addition volume ratio of the absolute ethyl alcohol to the glacial acetic acid to the distilled water is as follows: 20: 10: 5; uniformly mixing absolute ethyl alcohol and tetrabutyl titanate to obtain a solution B, wherein the volume ratio of the absolute ethyl alcohol to the tetrabutyl titanate is as follows: 2: 1;

(2) adding the solution A dropwise into the solution B under the condition of continuous magnetic stirring to form transparent sol, wherein the addition volume ratio of the solution B to the solution A is 30: 35; then the sol is moved into a reaction kettle with a polytetrafluoroethylene lining, and hydrothermal reaction is carried out for 5-10h at the temperature of 150-;

(3) after the hydrothermal reaction is finished, cooling the temperature to room temperature, taking out the reaction kettle, fully washing and separating the product to obtain a solid material;

(4) drying the solid material at 100 ℃ for more than 12 h;

(5) grinding the dried material uniformly to obtain the carboxyl-containing narrow forbidden band low-valence band modified TiO₂And (5) obtaining a finished product of the photocatalyst.

8. The narrow forbidden band low valence band modified TiO of claim 6₂The preparation method of the photocatalyst is characterized in that the electron-withdrawing group is carboxyl and is in TiO₂When the compound is introduced after synthesis, the method comprises the following steps:

(1) weighing nano TiO₂Finished granules of nano TiO with excess acetic acid₂Soaking the particles at room temperature for 12-24h in nano TiO₂Constructing a carboxyl chelating structure on the surface of the particle;

(2) after the impregnation is finished, the impregnated material is thermally treated for 10 hours at the temperature of 200 ℃, redundant acetic acid is removed, and the carboxyl-containing narrow forbidden band low-valence band modified TiO is prepared₂And (5) obtaining a finished product of the photocatalyst.

The technical field is as follows:

the present invention relates to TiO₂A preparation method of a photocatalyst, in particular to a narrow forbidden band low-valence band modified TiO₂A preparation method of the photocatalyst.

Background art:

TiO₂the photocatalyst has a wide forbidden band (more than 3.0eV), and the photocatalytic activity of the photocatalyst can be excited only by ultraviolet light. However, only about 3 to 5% of sunlight that reaches the earth's surface through the atmosphere contains ultraviolet components, and most of the visible and infrared components are harmful to the efficient use of solar energy and visible light.

At present, TiO is developed₂The effective approach of the photoresponse range is non-metal ion doping and self-structure modification. The basic principle of both methods is to TiO₂The valence band is modified, namely diffused impurity energy level is introduced near the top of the valence band in the forbidden band, so that the position of the top of the valence band is improved, and the width of the forbidden band is reduced. For example: patent cn201911015430.x discloses a preparation method of a divalent nickel ion doped modified titanium dioxide (nickel-titanium dioxide) visible-light-induced photocatalyst; the patent CN201810969987.6 discloses a preparation method of lanthanum-carbon co-doped modified titanium dioxide for degrading automobile exhaust; the patent CN201610464931.6 discloses a metal modified titanium dioxide hydrosol with high visible light activity, and synthesis and application thereof; patent CN201710425057.X discloses a method for preparing copper-nitrogen co-doped titanium dioxide nano powder based on a xerogel-hydrothermal method; patent CN201511024454.3 discloses a green titanium dioxide and its preparation method, modification method and application; and so on. The technical scheme disclosed by the patent mainly utilizes metal, non-metal ions and lattice defects to TiO₂The energy level of the doped silicon dioxide is introduced into the forbidden band, so that the forbidden band width is reduced. These methods have disadvantages, and metal ion doping tends to result in the TiO being prepared₂The thermal stability of the material is poor, and simultaneously, the doping of metal ions introduces oxygen vacancies which easily cause the increase of the recombination rate of photon-generated carriers, thereby causing the reduction of quantum efficiency; the doping of non-metal ions and lattice defects is carried out at the cost of increasing the position of a valence band, the forbidden band width is reduced, the loss of the oxidation capability of a photoproduction cavity is directly caused, and the photocatalysis is causedThe energy is reduced. These problems are described in the literature: chem.rev.2014,114, 9824-9852; analysis and discussion of the system among chem.rev.2014,114, 9890-9918.

The invention content is as follows:

to solve the above technical problems, the present invention provides a method for reducing TiO content₂The forbidden band width, the photocatalytic efficiency and the photocatalytic performance are improved, and the narrow forbidden band and the low-valence band are used for modifying TiO₂A preparation method of the photocatalyst.

The purpose of the invention is implemented by the following technical scheme: narrow forbidden band low valence band modified TiO₂Method for preparing photocatalyst on TiO₂During synthesis or in TiO₂After synthesis, a precursor containing a ligand with electron-withdrawing property is added, and the ligand with electron-withdrawing property and TiO are utilized₂The surface, interface and/or lattice gap matching is carried out to change the TiO from the micro₂The electronic environment around Ti and O in the crystal lattice induces O p orbital energy level and Ti d orbital energy level to be synchronously reduced, and the narrow forbidden band low-valence band modified TiO is constructed₂A photocatalyst.

Further, the TiO₂The synthesis method of (a) is any one of a sol-gel method, a hydrothermal method or a solvothermal method.

Further, the ligand having an electron withdrawing property is an electron withdrawing atom or an electron withdrawing group.

Further, the electron-withdrawing atom is any one or a combination of more than one of fluorine atom, chlorine atom or bromine atom.

Further, the electron-withdrawing atom is a fluorine atom and is present in TiO₂When the method is introduced in the synthesis process, the method comprises the following steps:

(1) mixing tetrabutyl titanate, 40 wt% hydrofluoric acid solution and distilled water at room temperature, and continuously stirring for more than 1h to prepare mixed solution; wherein the volume ratio of tetrabutyl titanate to 40 wt% hydrofluoric acid solution to distilled water is as follows: 30: 3.83: 5;

(2) transferring the mixed solution into a reaction kettle with a polytetrafluoroethylene lining, and carrying out hydrothermal reaction for 12-24h at the temperature of 150-;

(3) after the hydrothermal reaction is finished, separating the solid product, fully washing the solid product with distilled water and absolute ethyl alcohol, and drying the solid product at the temperature of 80 ℃ for more than 12 hours to prepare a solid material;

(4) carrying out heat treatment on the solid material at 300 ℃ for 2-4h to obtain the fluorine-containing narrow forbidden band low-valence band modified TiO₂And (5) obtaining a finished product of the photocatalyst.

Further, the electron-withdrawing group is any one or a combination of more than one of carboxyl, carbonyl, nitro or sulfonic acid group.

Further, the electron-withdrawing group is a carboxyl group and is in TiO₂When the method is introduced in the synthesis process, the method comprises the following steps:

(1) taking absolute ethyl alcohol, glacial acetic acid and distilled water, and uniformly mixing to obtain a solution A, wherein the addition volume ratio of the absolute ethyl alcohol to the glacial acetic acid to the distilled water is as follows: 20: 10: 5; uniformly mixing absolute ethyl alcohol and tetrabutyl titanate to obtain a solution B, wherein the volume ratio of the absolute ethyl alcohol to the tetrabutyl titanate is as follows: 2: 1;

(2) adding the solution A dropwise into the solution B under the condition of continuous magnetic stirring to form transparent sol, wherein the addition volume ratio of the solution B to the solution A is 30: 35; then the sol is moved into a reaction kettle with a polytetrafluoroethylene lining, and hydrothermal reaction is carried out for 5-10h at the temperature of 150-;

(3) after the hydrothermal reaction is finished, cooling the temperature to room temperature, taking out the reaction kettle, fully washing and separating the product to obtain a solid material;

(4) drying the solid material at 100 ℃ for more than 12 h;

(5) grinding the dried material uniformly to obtain the carboxyl-containing narrow forbidden band low-valence band modified TiO₂And (5) obtaining a finished product of the photocatalyst.

Further, the electron-withdrawing group is a carboxyl group and is in TiO₂When the compound is introduced after synthesis, the method comprises the following steps:

(1) weighing nano TiO₂Finished granules of nano TiO with excess acetic acid₂Soaking the particles at room temperature for 12-24h in nano TiO₂Constructing a carboxyl chelating structure on the surface of the particle;

(2)after the impregnation is finished, the impregnated material is thermally treated for 10 hours at the temperature of 200 ℃, redundant acetic acid is removed, and the carboxyl-containing narrow forbidden band low-valence band modified TiO is prepared₂And (5) obtaining a finished product of the photocatalyst.

The invention uses electron-withdrawing ligands to regulate TiO₂Energy band structure, modified TiO for constructing narrow forbidden band low-valence band₂The photocatalyst fundamentally avoids various problems caused by metal ion doping on one hand; on the other hand, the problems of valence band position reduction and photogenerated hole oxidation capacity loss caused by doping of non-metal ions and lattice defects are also avoided. The invention emphasizes the utilization of the electron-withdrawing characteristic of the electron-withdrawing ligand to regulate and control TiO₂The position of a valence band and a conduction band is changed due to the local electron environment, and the modified TiO with a narrow forbidden band and a low valence band is constructed₂A photocatalytic system.

The invention has the advantages that: the invention utilizes a ligand (atom or group) with electron-withdrawing property and TiO₂The surface, interface and/or lattice gap matching is carried out to change the TiO from the micro₂The electronic environment around Ti and O in the crystal lattice induces O p orbital level and Ti d orbital level to be synchronously reduced, so as to reduce TiO on one hand₂The purpose of forbidden bandwidth is to expand the visible light response range of the photocatalyst and improve the photocatalytic efficiency; on the other hand, the forbidden band width is reduced while the TiO is kept or reduced₂The valence band position ensures that the photoproduction cavity has stronger oxidation capacity and enhances the photocatalytic oxidation performance.

Drawings

FIG. 1 is a schematic representation of a TiO compound₂A ligand with electron-withdrawing property is introduced in the synthesis to prepare a flow chart.

FIG. 2 is a schematic representation of a TiO compound₂A scheme for preparing a ligand with electron-withdrawing property is introduced after synthesis.

FIG. 3 is a schematic representation of a TiO compound₂Carboxyl-containing and carboxyl-free TiO prepared by introducing carboxyl in synthesis₂UV-Vis DRS, VB-XPS and band structure comparison of samples are shown.

FIG. 4 is a schematic representation of a TiO compound₂UV-Vis DRS spectrum, VB-XPS spectrum and energy band of Ac-P25-200 sample containing carboxyl prepared by introducing carboxyl after synthesis and origin P25 sample containing no carboxylThe structure is compared with a schematic diagram.

FIG. 5 shows a cross-sectional view of a TiO compound₂UV-Vis DRS, VB-XPS and band structure comparison of the fluorine-containing 001TF-300 sample prepared by introducing fluorine during synthesis with the non-fluorine-containing 001T-300 sample are shown.

The specific implementation mode is as follows: