阅读说明：本技术 一种三元过渡金属氧化物的二维晶体材料及其制备方法 (Two-dimensional crystal material of ternary transition metal oxide and preparation method thereof ) 是由 朱景川 周飞 刘勇 来忠红 周易 于 2020-05-28 设计创作，主要内容包括：本发明公开了一种三元过渡金属氧化物的二维晶体材料及其制备方法,属于过渡金属氧化物光电子材料技术领域。本发明解决现有氧化物的二维材料制备方法制备三元过渡金属氧化物存在的问题。本发明采用水热辅助法和过饱和析出两步法以纯液相的方法析出二维KNbO<Sub>2</Sub>·xH<Sub>2</Sub>O二维晶体,通过控制过饱和度和生长时间,实现了KNbO<Sub>2</Sub>·xH<Sub>2</Sub>O二维晶体的厚度及横向尺寸可控生长,再通过简易的退火脱去结晶水,制备出了具有层状结构的KNbO<Sub>2</Sub>三元过渡金属氧化物的二维晶体材料。本申请进一步拓展了三元氧化物二维材料的制备方法,并且该方法有效避免传统水热法需要在密闭反应容器中固态原材料通过水热反应获得固态氧化物纳米材料。(The invention discloses a two-dimensional crystal material of ternary transition metal oxide and a preparation method thereof, belonging to the technical field of transition metal oxide photoelectron materials. The invention solves the problem of preparing the ternary transition metal oxide by the existing two-dimensional material preparation method of the oxide. The invention adopts a hydrothermal auxiliary method and a supersaturation precipitation two-step method to precipitate the two-dimensional KNbO by a pure liquid phase method 2 ·xH 2 The two-dimensional crystal O realizes KNbO by controlling the supersaturation degree and the growth time 2 ·xH 2 The thickness and the transverse dimension of the O two-dimensional crystal can be controlled to grow, and then the crystal water is removed by simple annealing, thus preparing the KNbO with the layered structure 2 Three-element processA two-dimensional crystalline material of a transition metal oxide. The preparation method of the ternary oxide two-dimensional material is further expanded, and the method effectively avoids the problem that the traditional hydrothermal method needs solid raw materials in a closed reaction container to obtain the solid oxide nano material through hydrothermal reaction.)

1. A two-dimensional crystal material of a ternary transition metal oxide, characterized in thatThe ternary transition metal oxide is KNbO₂The thickness of the ternary transition metal oxide two-dimensional crystal material is 0.7-100 nm, and the transverse dimension is 20-100 μm.

2. A method for producing a ternary transition metal oxide two-dimensional crystal material according to claim 1, characterized by comprising the steps of:

step one, preparing two-dimensional KNbO₂Precursor: mixing Nb with₂O₅Adding the powder into a KOH solution, uniformly mixing, and then preserving heat for 6-12 h at the temperature of 100-180 ℃ to obtain clear K⁺/Nb(OH)₄ ^-An ionic solution, namely the two-dimensional KNbO₂A precursor;

step two, the two-dimensional KNbO obtained in the step one is used₂Evaporating and dehydrating the precursor to obtain supersaturated K⁺/Nb(OH)₄ ^-Ionic solution, then supersaturated K⁺/Nb(OH)₄ ^-Transferring the ionic solution out of the heating equipment, cooling to room temperature to obtain KNbO₂·xH₂An ionic solution of O two-dimensional crystals;

step three, precipitating KNbO₂·xH₂Filtering and separating the ion solution of the O two-dimensional crystal to obtain solid KNbO₂·xH₂Transferring the O two-dimensional crystal to a high-temperature-resistant substrate, annealing to remove crystal water to obtain KNbO₂A two-dimensional crystalline material.

3. The method of claim 2, wherein Nb is added in the first step₂O₅The ratio of the powder to the KOH solution is (0.00005-0.0005) mol: 40ml, wherein the concentration of the KOH solution is 4-10 mol/L.

4. The method for preparing a ternary transition metal oxide two-dimensional crystal material according to claim 2, wherein Nb is added in the first step₂O₅Uniformly mixing the powder with a KOH solution, and then preserving the heat at 140-160 DEG C10h。

5. The method for preparing a ternary transition metal oxide two-dimensional crystal material according to claim 2, wherein said two-dimensional KNbO in the second step₂The evaporation dehydration temperature of the precursor ion solution is 50-70 ℃, and the evaporation dehydration time is 10 min-1 h.

6. The method for preparing a ternary transition metal oxide two-dimensional crystal material according to claim 2, wherein the filtration and separation treatment in the third step is a suction filtration method or a filter paper suction method.

7. The method for preparing a ternary transition metal oxide two-dimensional crystal material according to claim 2, wherein the annealing temperature in the third step is 300 to 400 ℃.

8. The method for producing a ternary transition metal oxide two-dimensional crystal material according to claim 7, wherein the annealing temperature in the third step is 350 ℃.

9. The method for preparing a ternary transition metal oxide two-dimensional crystal material according to claim 2, wherein the refractory substrate in step three is SiO₂a/Si substrate.

Technical Field

The invention relates to a two-dimensional crystal material of ternary transition metal oxide and a preparation method thereof, belonging to the technical field of transition metal oxide photoelectron materials.

Background

Transition metal oxides are widely used in the fields of electronics, optics and catalysis as an important functional material. As the dimensions of the material decrease, oxide two-dimensional materials exhibit many novel physical properties not possessed by bulk materials. However, the preparation of oxide two-dimensional materials has been a difficult point of research in the field of oxide functional materials for a long time, and the existing methods for preparing oxide two-dimensional materials include: (1) the epitaxial growth method obtains the oxide superlattice film with the nanometer scale by the mode of molecular beam epitaxial growth (MBE) or Pulsed Laser Deposition (PLD), but the condition for growing ternary oxidation is very harsh and cannot get rid of the limitation of substrate lattice matching, so that researchers have great limitation on the research of two-dimensional oxide, and particularly, the method has huge challenge on the preparation of a volatile alkali metal niobate system at high temperature, is expensive, has strict and complex process control, and is difficult to realize large-scale industrial production. (2) Hydrothermal method, which is a mature oxide synthesis method, is widely used in the preparation of oxide nanostructures. However, the method is limited by a closed reaction process, and the reaction process cannot be controlled except for changing the mass-solubility ratio and using a surfactant, so that the prepared two-dimensional oxide exists in the form of nano-flakes, and the two-dimensional size of the two-dimensional oxide is limited to dozens of nanometers to hundreds of nanometers. Therefore, the two-dimensional nano-flake prepared by the method is limited to the research and application in the field of catalysis. (3) The liquid surface reaction method is used for preparing an oxide two-dimensional material by controlling the surface reaction of liquid metal or ionic liquid, but the method is only limited to the preparation of a two-dimensional material of a binary oxide at present and cannot be expanded to the preparation of a ternary oxide.

Disclosure of Invention

The invention provides a novel preparation method of a ternary transition metal oxide two-dimensional crystal material and a two-dimensional crystal material prepared by the method, aiming at solving the problems of the existing preparation method of the ternary oxide two-dimensional crystal material.

The technical scheme of the invention is as follows:

a two-dimensional crystal material of ternary transition metal oxide, the ternary transition metal oxide is KNbO₂The thickness of the ternary transition metal oxide two-dimensional crystal material is 0.7-100 nm, and the transverse dimension is 20-100 μm.

The above ternary transition metal oxide (KNbO)₂) The method for preparing a two-dimensional crystalline material of (1), which comprises the steps of:

step one, preparing two-dimensional KNbO₂Precursor: mixing Nb with₂O₅Adding the powder into a KOH solution, uniformly mixing, and then preserving heat for 6-12 h at the temperature of 100-180 ℃ to obtain clear K⁺/Nb(OH)₄ ^-An ionic solution, namely the two-dimensional KNbO₂A precursor;

step two, the two-dimensional KNbO obtained in the step one is used₂Evaporating and dehydrating the precursor to obtain supersaturated K⁺/Nb(OH)₄ ^-Ionic solution, then supersaturated K⁺/Nb(OH)₄ ^-Transferring the ionic solution out of the heating device, cooling to room temperature to obtain separated KNbO₂·xH₂An ionic solution of O two-dimensional crystals;

step three, precipitating KNbO₂·xH₂Filtering and separating the ion solution of the O two-dimensional crystal to obtain solid KNbO₂·xH₂Transferring the O two-dimensional crystal to a high-temperature-resistant substrate, annealing to remove crystal water to obtain KNbO₂A two-dimensional crystalline material.

Further defining, Nb in step one₂O₅The ratio of the powder to the KOH solution is (0.00005-0.0005) mol: 40ml, wherein the concentration of the KOH solution is 4-10 mol/L.

Further defining, in step one, Nb₂O₅And uniformly mixing the powder with a KOH solution, and then preserving the heat for 10 hours at the temperature of 140-160 ℃.

Further limiting, in the second step, two-dimensional KNbO₂The evaporation dehydration temperature of the precursor is 50-70 ℃, and the evaporation dehydration time is 10 min-1 h.

Further limiting, the filtration and separation treatment in the third step is a suction filtration method or a filter paper suction method.

Further limiting, the annealing treatment temperature in the third step is 300-400 ℃.

More specifically, the annealing temperature in the third step is 350 ℃.

Further limiting, in the third step, the high temperature resistant substrate is SiO₂a/Si substrate.

The invention has the following beneficial effects: the invention adopts a two-step method of hydrothermal assistance and supersaturation precipitation to precipitate the two-dimensional KNbO by a pure liquid phase method₂·xH₂The two-dimensional crystal O realizes KNbO by controlling the supersaturation degree and the growth time₂·xH₂The thickness and the transverse dimension of the O two-dimensional crystal can be controlled to grow, and then the crystal water is removed by simple annealing, thus preparing the KNbO with the layered structure₂A ternary transition metal oxide two-dimensional crystalline material. The method effectively avoids the problem that the traditional hydrothermal method needs solid raw materials in a closed reaction container to obtain the solid oxide nano material through hydrothermal reaction. Compared with the epitaxial method and the liquid metal surface reaction method in the prior art, the method has the advantages of low raw material and preparation cost, simple process and strong controllability.

Drawings

FIG. 1 is a schematic view of a material preparation process of the present invention;

FIG. 2 shows KNbO₂A schematic diagram of the atomic structure of a two-dimensional material;

FIG. 3 shows KNbO₂A schematic cross-sectional view of a two-dimensional material;

FIG. 4 shows KNbO₂A schematic diagram of a two-dimensional material stack structure;

FIG. 5 shows KNbO₂Schematic representation of a two-dimensional crystal, wherein (d)) Is KNbO₂Two-dimensional crystal is arranged in SiO₂Optical micrograph on/Si substrate, (e) KNbO₂A two-dimensional crystal atomic force microscope scanning image, (f) is a height profile measurement schematic diagram of (e);

FIG. 6 shows KNbO₂X-ray diffraction pattern of two-dimensional crystal, wherein (g) is KNbO₂X-ray diffraction pattern of two-dimensional crystal, (h) KNbO₂An X-ray photoelectron spectroscopy analysis of the two-dimensional crystal;

FIG. 7 shows KNbO₂The energy dispersion spectrum imaging result of the two-dimensional crystal;

FIG. 8 shows KNbO₂A selected area electron diffraction transmission microscope photograph in a two-dimensional crystal plane;

FIG. 9 shows KNbO with different thicknesses₂The two-dimensional crystal nanosheet is in a shape.

Detailed Description

The experimental procedures used in the following examples are conventional unless otherwise specified. The materials, reagents, methods and apparatus used, unless otherwise specified, are conventional in the art and are commercially available to those skilled in the art.