阅读说明：本技术 一种缺陷富集的TiO2纳米片一维多级结构的制备方法 (Defect-enriched TiO2Preparation method of nanosheet one-dimensional multilevel structure ) 是由 董文钧 董诚 王戈 高鸿毅 苏天琪 张立国 常月琪 周冬雪 于 2019-10-11 设计创作，主要内容包括：本发明公开了一种缺陷富集的TiO_2纳米片一维多级结构的制备方法,属于纳米材料制备技术领域。所述方法包括：取二氧化钛粉末、水、氢氧化钠/氢氧化钾置于反应釜中；超声30min后水热条件下反应,得到缺陷富集的钛酸盐多级纳米片结构；用去离子水将前一步骤得到产物冲洗至溶液PH值等于7,干燥后将该产物放入管式炉中煅烧,得到缺陷富集的TiO_2多级纳米片结构。应用本发明的方法能够廉价、稳定地得到缺陷富集的TiO_2多级纳米片结构。本方法条件温和,重复性极好,工艺简单、可控,制得的产物纯度高。(The invention discloses defect-enriched TiO 2 A preparation method of a one-dimensional multilevel structure of a nano-sheet belongs to the technical field of nano-material preparation. The method comprises the following steps: putting titanium dioxide powder, water and sodium hydroxide/potassium hydroxide into a reaction kettle; carrying out ultrasonic treatment for 30min, and then carrying out reaction under a hydrothermal condition to obtain a defect-enriched titanate multistage nanosheet structure; washing the product obtained in the previous step with deionized water until the pH value of the solution is equal to 7, drying, and calcining the product in a tubular furnace to obtain defect-enriched TiO 2 A multi-stage nanosheet structure. The method of the invention can be used for obtaining the defect-enriched TiO with low cost and stability 2 A multi-stage nanosheet structure. The method has the advantages of mild conditions, excellent repeatability, simple and controllable process and high purity of the prepared product.)

1. Defect-enriched TiO₂The preparation method of the one-dimensional multilevel structure of the nano sheet is characterized by comprising the following steps:

step 1: putting titanium dioxide powder, water and sodium hydroxide/potassium hydroxide into a reaction kettle;

step 2: carrying out ultrasonic treatment for 30min, and then carrying out reaction under a hydrothermal condition to obtain a defect-enriched titanate multistage nanosheet structure;

and step 3: washing the product obtained in the step 2 by using deionized water until the pH value of the solution is equal to 7, drying, and then putting the product into a tubular furnace for calcining to obtain defect-enriched TiO₂The multi-stage nano-sheet structure comprises a plurality of nano-sheets,

wherein the lining material of the reaction kettle is a polytetrafluoroethylene porous material.

2. The method according to claim 1, wherein in step 1, the mass ratio of titanium dioxide powder, water and sodium hydroxide/potassium hydroxide is: 0.05-0.3:30-80:10-40.

3. The method as claimed in claim 1, wherein the hydrothermal reaction is carried out at 250 ℃ for 1 to 7 days in step 2.

4. The method according to claim 1, wherein in step 1, the mass ratio of titanium dioxide powder, water and sodium hydroxide/potassium hydroxide is: 0.1:50:18, the hydrothermal reaction temperature is 220 ℃, and the reaction time is 6 days.

5. The production method according to claim 1, wherein in step 1, 0.1g of titanium dioxide powder, 50mL of water and 18g of sodium hydroxide are reacted, and the reaction vessel is 100 mL.

6. The method as claimed in claim 1, wherein the calcination in step 3 is carried out under conditions of 300-500 ℃ in an air atmosphere for 1-3 h.

7. The method according to claim 6, wherein the calcining is performed under the condition of 350 ℃ for 2 hours in an air atmosphere in the step 3.

8. Defect-enriched TiO₂A nanosheet one-dimensional multilevel structure, characterized in that the defect-enriched TiO₂A nanosheet one-dimensional multilevel structure prepared using the method of preparation of any one of claims 1 to 7, the TiO being₂The one-dimensional multilevel structure of the nano-sheet is formed by TiO₂The nano sheets are mutually cross-linked and wound to form the nano-composite material.

Technical Field

The invention belongs to the technical field of nano material preparation, and particularly relates to defect-enriched TiO₂A preparation method of a nano-sheet one-dimensional multilevel structure.

Background

Due to the wide application of the nanosheet material in the fields of catalysis, energy environments and the like, researches on the preparation and application of the nanosheet material are more and more. In addition, it has been a hot point of research to make the nanoplate have high activity, wherein, manufacturing the nanoplate with enriched defects is an important method for improving the activity of the nanoplate. However, the defect-enriched nanosheets have ultrahigh surface free energy, so that the nanosheets are extremely easy to agglomerate in the preparation and use processes, and the development of the defect-enriched nanosheet material in the practical application process is severely restricted. Therefore, how to orderly assemble the defect-enriched nanosheets to meet the ever-increasing demands of people is the direction of efforts of researchers.

At present, methods for loading nano sheets on carbon fiber, metal sheets and other templates are widely researched, and particularly materials composed of high-activity functional nano sheets such as titanium oxide, zinc oxide, molybdenum oxide and the like are hot spots of research. However, the methods all need to introduce templates before and after or during the reaction, so that the preparation process is more complicated and the cost is higher, the introduced templates can influence the relevant performance of the material, and a template-free one-dimensional multilevel structure assembled by defect-enriched nanosheets is not reported at present. Therefore, creating a method which is simple to prepare, low in cost and free from introducing a template, and the preparation of the one-dimensional multilevel structure assembled by the defect-enriched nanosheets becomes a problem which needs to be solved urgently.

Disclosure of Invention

To solve the above problems, it is an object of the present invention to prepare defect-enriched TiO by adjusting the conditions of temperature, solution concentration, etc. in the hydrothermal reaction process₂A multi-stage nanosheet structure.

According to a first aspect of the present invention there is provided a defect-enriched TiO₂The preparation method of the one-dimensional multilevel nano-sheet structure comprises the following steps:

step 1: putting titanium dioxide powder, water and sodium hydroxide/potassium hydroxide into a reaction kettle;

step 2: carrying out ultrasonic treatment for 30min, and then carrying out reaction under a hydrothermal condition to obtain a defect-enriched titanate multistage nanosheet structure;

and step 3: washing the product obtained in the step 2 by using deionized water until the pH value of the solution is equal to 7, drying, and then putting the product into a tubular furnace for calcining to obtain defect-enriched TiO₂A multi-stage nanosheet structure.

Further, in step 1, the mass ratio of titanium dioxide powder, water and sodium hydroxide/potassium hydroxide is: 0.05-0.3:30-80:10-40.

Further, in step 2, the hydrothermal reaction is carried out at 210 ℃ and 250 ℃ for 1-7 days.

Further, in step 1, the mass ratio of titanium dioxide powder, water and sodium hydroxide/potassium hydroxide is: 0.1:50:18, the hydrothermal reaction temperature is 220 ℃, and the reaction time is 6 days.

Further, in step 1, 0.1g of titanium dioxide powder, 50mL of water and 18g of sodium hydroxide were reacted in a reaction vessel of 100 mL.

Further, in the step 3, the calcination condition is that calcination is carried out for 1-3h at the temperature of 300-500 ℃ under the air atmosphere.

Further, in step 3, the calcination condition is calcination at 350 ℃ for 2h under an air atmosphere.

According to a second aspect of the present invention, there is provided a defect-enriched TiO₂Nanosheet one-dimensional multilevel structure, wherein the defect-enriched TiO₂The one-dimensional multilevel structure of the nanosheet is prepared by the method according to any one of the above aspects.

The invention has the beneficial effects that: the method of the invention can be used for obtaining the defect-enriched TiO with low cost and stability₂A multi-stage nanosheet structure. The method has the advantages of mild conditions, excellent repeatability, simple and controllable process and high purity of the prepared product. TiO enriched by defects₂The one-dimensional nanowire formed by the mutual cross-linking and winding of the nanosheets can stabilize the defect of high activity in a multilevel structure, avoid the agglomeration of a high-activity surface in the use process and enable the high-activity surface to have wide application prospects in the fields of energy storage, catalysis and the like.

Drawings

FIG. 1 shows defect enriched TiO according to the invention₂A flow chart of a preparation method of the nano sheet one-dimensional multilevel structure;

FIG. 2(a) is an SEM photograph of the hydrothermal reaction for 2 hours;

FIG. 2(b) is a schematic view showing the reaction state after the reaction has proceeded for 3 hours;

FIG. 3(a) is a schematic view showing the reaction state after the reaction has proceeded for 4 hours;

FIG. 3(b) is a schematic view showing the state of the reaction when the reaction is continued;

FIG. 4 is a defect enriched TiO of the present invention₂SEM pictures of the multilevel nanosheet structure;

FIG. 5 is a defect enriched TiO of the present invention₂TEM pictures of the multilevel nanosheet structure;

FIGS. 6 and 7 show defect-enriched TiO compounds according to the present invention₂HR-TEM pictures of the multilevel nanosheet structure;

FIG. 8 is defect-enriched TiO prepared in example 1₂Electron Paramagnetic Resonance (EPR) spectra of multilevel nanosheet structures;

FIG. 9 is defect-enriched TiO prepared in example 2₂Electron Paramagnetic Resonance (EPR) spectra of multilevel nanosheet structures;

FIG. 10 is defect-enriched TiO prepared in example 3₂Electron Paramagnetic Resonance (EPR) spectra of multilevel nanosheet structures.

Detailed Description

The invention will be further elucidated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention will occur to those skilled in the art after reading the present disclosure, and such equivalents will fall within the scope of the appended claims.

The invention relates to defect-enriched TiO₂A preparation method of a nano-sheet one-dimensional multilevel structure. As shown in fig. 1, the method specifically comprises:

step 101: putting P25, water and sodium hydroxide/potassium hydroxide into a reaction kettle, wherein the mass ratio of P25 to water to sodium hydroxide/potassium hydroxide is as follows: 0.05-0.3:30-80: 10-40;

step 102: reacting for 1-7 days under the hydrothermal condition of 210-250 ℃ after ultrasonic treatment for 30min to obtain a defect-enriched titanate multistage nanosheet structure;

step 103: then repeatedly washing the product with deionized water until the pH value of the solution is equal to 7, drying, then putting the product into a tubular furnace, calcining for 1-3h at the temperature of 500 ℃ in the air atmosphere to obtain defect-enriched TiO₂A multi-stage nanosheet structure.

The mass ratio of the titanium dioxide powder to the water to the sodium hydroxide/potassium hydroxide is as follows: 0.1:50:18, the hydrothermal reaction temperature is 220 ℃, and the reaction time is 6 days. The calcining temperature of the tubular furnace is 350 ℃, and the calcining time is 2 h. 0.1g P25, 50mL water and 18g sodium hydroxide, 100mL reactor.

Said defect-enriched TiO₂One-dimensional multilevel nano-wire of multilevel nano-sheet structure made of TiO₂The nano sheets are mutually cross-linked and wound to form the nano-composite material.

The polytetrafluoroethylene is a porous material and is a commonly used lining material of a reaction kettle in a hydrothermal reaction. However, the prior art has not studied and utilized its porous properties. The invention firstly utilizes the porous performance of the polytetrafluoroethylene to nucleate and grow the nanowire in the pores of the polytetrafluoroethylene. After the reactants are put into the polytetrafluoroethylene lining, the container is put into an ultrasonic machine for 30min of ultrasonic treatment, so that titanium dioxide powder can enter the holes of the polytetrafluoroethylene lining, and the reaction can be preferentially carried out in the holes of the inner wall after heating. FIG. 2(a) is an SEM photograph of hydrothermal reaction for 2h, from which it can be seen that nanorods grew from the pores in the inner wall of the reaction vessel. After the reaction is carried out for 3 hours, as shown in FIG. 2(b), the nanorods continuously grow into a nanowire structure. Because the nanowires are fixed on the side wall of the reaction kettle instead of sinking to the bottom of the reaction kettle, the material exchange can be more sufficient, and unique conditions are provided for the next structural change.

After the reaction is carried out for 4h, the titanate nanowires still have a solid structure, as shown in fig. 3 (a). When the reaction continues, the surface of the nanowire reaches dynamic balance, and the splitting and dissolving processes are continuously generated on the surface, as shown in fig. 3(b), after the reaction occurs for 6 hours, the splitting and dissolving processes of the nanowire and the generation of the nanosheet can be observed. The dissolved raw materials promote the continuous recrystallization in the solution, and the recrystallization process is easier to occur on the existing material interface rather than independent nucleation, thus finally realizing the epitaxial growth of the nano-sheets on the nano-wires. In addition, the condition that the product is always suspended in the solution rather than settled enables the process to be carried out rapidly, and simultaneously accelerates the material flow and exchange of a reaction system, so that the growth of the nano-sheets is not sufficient and incomplete, and a large number of defects are generated. Finally, the invention utilizes the dissolution-recrystallization process which continuously occurs in the hydrothermal process, and utilizes the process and the amplification process to realize the self-assembly of the growth of the nano-sheets, so that the original one-dimensional nanowire structure is continuously split and dissolved, and the nano-sheets gradually recrystallize and grow on the nanowires to obtain the one-dimensional multilevel structure completely composed of the nano-sheets. Because the dissolving-recrystallizing process is a dynamic equilibrium process, the dissolving of the nano-wires provides raw materials required by the growth of the nano-sheets, and the insufficient raw materials cause the generation of a large amount of defects in the nano-sheets, thereby further obtaining the defect-enriched TiO₂A multi-stage nanosheet structure.