Method and structure for forming two-dimensional cadmium sulfide on substrate in large area
阅读说明：本技术 基底上大面积形成二维硫化镉的方法与结构 (Method and structure for forming two-dimensional cadmium sulfide on substrate in large area ) 是由 张阳阳 吴昊 李江宇 于 2019-12-03 设计创作，主要内容包括：本发明涉及一种基底上大面积形成二维硫化镉的方法与结构,方法包括:制备有机镉盐溶液;提供两相体系溶剂,上层为非极性溶剂层,下层为极性溶剂层;有机镉盐溶液的混入使有机镉盐聚集于非极性溶剂层与极性溶剂层的界面处;硫前驱体溶液溶入下层极性溶剂层;蒸发上层非极性溶剂层,使界面处的有机镉盐随非极性溶剂层体积减小而聚集成膜,漂浮于极性溶剂层的液面,并与极性溶剂层中的硫离子反应,以生成二维硫化镉膜层;二维硫化镉膜层沾附于基底的表面上。本发明具有制作超薄纳米级二维硫化镉膜层或/与在任意基底上低成本制备大面积二维硫化镉的效果,具有省时、节能,绿色环保、制备成本低和易于大规模工业化生产等优势。(The invention relates to a method and a structure for forming two-dimensional cadmium sulfide on a substrate in a large area. The method has the effects of manufacturing the ultrathin nanoscale two-dimensional cadmium sulfide film layer or/and preparing large-area two-dimensional cadmium sulfide on any substrate at low cost, and has the advantages of time saving, energy saving, environmental friendliness, low preparation cost, easiness in large-scale industrial production and the like.)
1. A method for forming a two-dimensional cadmium sulfide over a large area on a substrate, comprising:
preparing an organic cadmium salt solution (10);
providing a two-phase system solvent (20), wherein the upper layer of the two-phase system solvent (20) is a non-polar solvent layer (21), and the lower layer is a polar solvent layer (22);
the organic cadmium salt solution (10) is dissolved into the nonpolar solvent layer (21) which is positioned at the upper layer, and the organic cadmium salt of the organic cadmium salt solution (10) is gathered at the interface of the nonpolar solvent layer (21) and the polar solvent layer (22);
a sulphur precursor solution (30) is dissolved into the polar solvent layer (22) located below;
evaporating the nonpolar solvent layer (21) positioned at the upper layer, so that organic cadmium salt at the interface is gathered into a film as the volume of the nonpolar solvent layer (21) is reduced, floats on the liquid surface of the polar solvent layer (22), and reacts with sulfur ions in the polar solvent layer (22) to generate a two-dimensional cadmium sulfide film layer (40);
the two-dimensional cadmium sulfide film layer (40) adheres to the surface of the substrate (50).
2. The method for forming the two-dimensional cadmium sulfide on the substrate in the large area according to claim 1, wherein the thickness of the two-dimensional cadmium sulfide film layer is less than 10 nanometers (nm), preferably the thickness of the two-dimensional cadmium sulfide film layer is 0.5-3.0 nm, and more preferably the thickness of the two-dimensional cadmium sulfide film layer is 1.0-1.2 nm.
3. The method for forming two-dimensional cadmium sulfide on a substrate in a large area according to claim 1, wherein during the evaporation of the nonpolar solvent layer (21) on the upper layer, the current evaporation temperature is equal to or higher than the current atmospheric-pressure boiling point of the nonpolar solvent layer (21) on the upper layer, lower than the current atmospheric-pressure boiling point of the polar solvent layer (22) on the lower layer, and lower than the current atmospheric-pressure boiling point of the organic cadmium salt, and specifically, the current evaporation temperature is between room temperature and 80 ℃.
4. The method for forming two-dimensional cadmium sulfide on a substrate in a large area according to claim 1, wherein the organic cadmium salt solution (10) comprises a fatty acid cadmium salt and a pre-dissolved nonpolar solvent, the carbon chain length of the fatty acid group is 4-30, and the number of unsaturated bonds is 0-28.
5. Method for the large-area formation of two-dimensional cadmium sulfide on a substrate according to claim 4, characterized in that the amount of organic cadmium salt of the organic cadmium salt solution (10) is in a positive relationship with the liquid level area of the polar solvent layer (22), preferably according to: (1～1000) ×1.6 ×10-8kg of cadmium salt of fatty acid dissolved in (20-40) × 10-6 m3Is pre-dissolved in a non-polar solvent, and the volume is nS multiplied by 5 multiplied by 10-10And C1, wherein n = 1-1000, S is the liquid surface area of the polar solvent layer, and c1 is the concentration of the organic cadmium salt solution, and the fatty acid cadmium solution (10) is dissolved into the nonpolar solvent layer (21) positioned at the upper layer.
6. Method for large area formation of two-dimensional cadmium sulfide on a substrate according to claim 5, wherein the sulfur precursor solution (30) comprises (NH)4）2S or/and Na2S soluble sulfur-containing aqueous solution and pre-dissolved polar solvent.
7. Method for the large-area formation of two-dimensional cadmium sulfide on a substrate according to claim 6, wherein the amount of the sulfur precursor in the sulfur precursor solution (30) is in a positive relationship with the amount of the organic cadmium salt in the organic cadmium salt solution (10), preferably according to (1-1000) x 2 x 10-11 m3(NH) at a concentration of 8wt.%4）2S or/and Na2S soluble sulfur-containing aqueous solution is dissolved in (20-40) x 10-6 m3And taking the volume of 2n multiplied by 10-8 m3Is dissolved into the underlying polar solvent layer (22).
8. The method of claim 1, wherein the organic cadmium salt has hydrophobic groups (12) that are embossed in the liquid surface (23) of the polar solvent layer (22) after evaporation of the non-polar solvent layer (21), or/and the organic cadmium salt has hydrophilic groups (13) that float on the liquid surface (23) of the polar solvent layer (22) after evaporation of the non-polar solvent layer (21).
9. The method for forming two-dimensional cadmium sulfide on a substrate in a large area according to claim 1, wherein in the step of adhering the two-dimensional cadmium sulfide film layer (40) on the surface of the substrate (50), the substrate (50) is vertically inserted into the polar solvent layer (22) and then slowly tilted up to obtain the two-dimensional cadmium sulfide film layer (40) adhered on the substrate (50).
10. The method for forming two-dimensional cadmium sulfide on a substrate in a large area according to claim 1, wherein the organic cadmium salt is selected from one of cadmium oleate, cadmium elaeate, cadmium stearate, cadmium palmitoleate, cadmium arachidonic acid, cadmium eicosapentaenoic acid, cadmium docosapentaenoic acid and cadmium laurate, and the nonpolar solvent layer is selected from one of toluene and its homologues, acetone and its homologues, chloroform and its analogues, and n-hexane which has a specific gravity smaller than that of the polar solvent layer; the polar solvent layer is selected from water or amides.
11. The method for forming a large area of two-dimensional cadmium sulfide on a substrate according to any one of claims 1 to 10, further comprising the steps of: after the organic cadmium salt solution (10) is dissolved and before the step of evaporating the nonpolar solvent layer (21) located at the upper layer, the two-phase system solvent (20) is left to stand for clearly separating the nonpolar solvent layer (21) from the polar solvent layer (22), and the step of evaporating the nonpolar solvent layer (21) located at the upper layer includes: completely volatilizing the nonpolar solvent layer (21), providing standing time for film layer generation for 1-36 hours, and performing a step of dissolving a sulfur precursor solution (30) into the polar solvent layer (22) positioned at the lower layer after the step of completely volatilizing the nonpolar solvent layer (21) and before the standing step for film layer generation, or performing a step of dissolving the organic cadmium salt solution (10) into the nonpolar solvent layer (21) positioned at the upper layer and before the step of completely volatilizing the nonpolar solvent layer (21).
12. A structure for forming two-dimensional cadmium sulfide on a substrate in a large area, which is obtained by the method for forming two-dimensional cadmium sulfide on a substrate in a large area according to any one of claims 1 to 11.
13. A nano plate-like structure for preparing hydrogen by photocatalytic hydrolysis is characterized by comprising: a substrate having a large area formed thereon a two-dimensional cadmium sulfide structure as claimed in claim 12.
Technical Field
The invention relates to the technical field of preparation of cadmium sulfide, in particular to a method for forming two-dimensional cadmium sulfide on a substrate in a large area, and the method can be particularly applied to a nano plate-shaped structure for hydrogen production through photocatalytic hydrolysis.
Background
Along with the increasing exhaustion of fossil energy and ecological environmentThe rapid deterioration of the environment, and the search for new renewable green energy becomes one of effective means for relieving the energy crisis. The hydrogen energy has the advantages of no pollution, high heat value, rich reserves and the like, is an ideal pollution-free green energy in the new century, and is highly valued by various countries. First reported TiO in 1972 by Tokyo university of Japan2The electrode can generate hydrogen by photocatalytic water decomposition, thereby opening up a research road for hydrogen production by solar water decomposition.
In the prior art, cadmium sulfide is known to belong to a two-dimensional transition metal chalcogenide, is a direct band gap semiconductor material, has a bulk band gap of 2.42eV, has good response capability to visible light, and has attracted extensive attention in the fields of photocatalytic degradation, hydrogen production and the like due to the narrow forbidden band width and the proper energy band position of CdS. CdS (nano-particles, quantum dots, nano-fibers, nano-rods, nano-plates, nano-sheets and the like) with various structures are prepared and show extremely high catalytic activity on photocatalytic hydrolysis hydrogen production, and compared with zero-dimensional or one-dimensional CdS, the two-dimensional CdS nano-sheets can provide more exposed surface atoms for light collection due to a plurality of active centers exposed at the edges; the two-dimensional sheet structure shortens the migration distance of a photon-generated carrier from the inside to the surface, has high electron mobility, and promotes the separation and transfer of photon-generated electron-hole pairs, thereby occupying the most advantage in the photocatalytic hydrolysis hydrogen production.
At present, various methods are tried to prepare the CdS nano-material, and a hydrothermal method, a solvothermal method, a chemical water bath deposition method, an atomic layer deposition method, a chemical reduction method and the like are commonly used, but most of the obtained nano-materials are still one-dimensional nanowires or small-area quasi-two-dimensional nanosheets or thicker nano-plate-shaped structures, and a two-dimensional CdS preparation process with a thickness of a few nanometers in a large area is not mature in a real sense (for example, the actual film thickness is difficult to reach less than or equal to 10 nm). For example, a hydrothermal method and other liquid phase methods for preparing CdS often need heating, and a surfactant or a template and the like are added, so that the cost is high, the process is complex, and the conditions are harsh; therefore, a new preparation method with low cost and simplicity and convenience is urgently needed to obtain a large-area ultrathin two-dimensional CdS nano material. Several known hydrothermal liquid phase CdS formation techniques are exemplified below.
The invention patent application publication No. CN1819127A discloses a process for producing a single-phase reaction cadmium sulfide film, which comprises the steps of preparing and injecting a raw material solution, dissolving cadmium salt, ammonium salt, a water-soluble sulfur-containing organic compound, ammonia water and zinc chloride in purified water, adding hot water into the prepared raw material solution, keeping the water temperature constant between 70 ℃ and 95 ℃, introducing ultrasonic waves, pouring out the reaction solution, adding distilled water at the same temperature, oscillating and cleaning, pouring out a cleaning solution, adding 1wt% -5wt% of an ammonia nitrate solution, carrying out ultrasonic cleaning at the same temperature, pulling out rough particles on the surface, and finally forming a uniform cadmium sulfide film. The film thickness was on the order of centimeters.
The invention patent application publication No. CN103643225A discloses a method for preparing a large-size cadmium sulfide film by a chemical water bath method of single-phase reaction, wherein one surface of a substrate which does not need to be coated is fixed in a reaction vessel in a closed manner; injecting a reaction solution containing cadmium salt, a sulfur source, ammonia water and deionized water into the reaction container, and then sealing the reaction container; horizontally immersing a sealed reaction container into a constant-temperature water bath oscillator, heating the water bath, and ceaselessly and uniformly mixing reaction solution in a mode of rotating and reciprocating in the horizontal direction or swinging up and down by taking a central shaft as an axis so as to deposit a uniform cadmium sulfide film on the unclosed surface of the substrate; and (4) after the cadmium sulfide film is deposited to the required thickness, taking out, cleaning and drying to obtain the large-size cadmium sulfide film. The film thickness of the cadmium sulfide film is 50-80 nm.
The invention patent application publication No. CN104701413A discloses a preparation method of a large-area cadmium sulfide film, wherein a substrate is composed of an MO and CIGS composite substrate prepared on a glass substrate, and a water bath kettle is a large-caliber water bath kettle with a magnetic rotor to improve temperature gradient. A CdS film with the area of 10cm multiplied by 10cm is prepared by a chemical water bath method with ammonia water with high concentration and without a buffering agent. The CdS film is prepared on the substrate of the copper indium gallium selenide solar cell under the condition of high ammonia by using a chemical water bath method. The method has special requirements on the material of the substrate, is applied to the copper indium gallium selenide solar cell, and does not disclose that the film thickness reaches the ultrathin design.
Disclosure of Invention
One of the main objects of the present invention is to provide a method for forming two-dimensional cadmium sulfide on a substrate in a large area, so as to achieve the technical problem of how to manufacture an ultra-thin nanoscale two-dimensional cadmium sulfide film layer or/and to prepare large-area two-dimensional cadmium sulfide on any substrate at low cost.
The invention also aims to provide a structure for forming the two-dimensional cadmium sulfide on the substrate in a large area, which can form a nanoscale two-dimensional cadmium sulfide film layer on a plate in a large area and is used for realizing the application in the field of hydrogen production by photocatalytic hydrolysis.
One of the main objects of the present invention is achieved by the following technical solutions:
a method for forming two-dimensional cadmium sulfide on a substrate in a large area is provided, which comprises the following steps: the method comprises the steps of preparing an organic cadmium salt solution, providing a two-phase system solvent, dissolving the organic cadmium salt solution into the nonpolar solvent layer positioned on the upper layer, enabling the organic cadmium salt of the organic cadmium salt solution to be gathered at the interface of the nonpolar solvent layer and the polar solvent layer, dissolving a sulfur precursor solution into the polar solvent layer positioned on the lower layer, evaporating the nonpolar solvent layer positioned on the upper layer, enabling the organic cadmium salt at the interface to be gathered into a film along with the reduction of the volume of the nonpolar solvent layer, enabling the film to float on the liquid surface of the polar solvent layer and react with sulfur ions in the polar solvent layer, and attaching the two-dimensional cadmium sulfide film layer to the surface of a substrate.
By adopting the basic technical scheme, the two-dimensional cadmium sulfide film layer is formed by evaporating the nonpolar solvent layer to gradually enable the organic cadmium salt to be polymerized into the film, float on the liquid surface of the polar solvent layer and react with sulfur ions of the polar solvent layer, the obtained two-dimensional cadmium sulfide film layer can be attached to the surface of the substrate in a large area and can also reach the thickness of a nanometer grade film, the process temperature of the main steps is the upper limit of the boiling point of the polar solvent layer, the low-temperature manufacture can be achieved, and the qualified state of the process can be easily identified.
The present invention in a preferred example may be further configured to: the thickness of the two-dimensional cadmium sulfide film layer is less than 10 nanometers (nm), preferably, the thickness of the two-dimensional cadmium sulfide film layer is 0.5-3.0 nanometers, and more preferably, the thickness of the two-dimensional cadmium sulfide film layer is 1.0-1.2 nanometers.
By adopting the preferable technical scheme, the organic cadmium salt gradually gathers into the film and floats on the liquid surface of the polar solvent layer when the nonpolar solvent layer is evaporated and reacts with the sulfur ions moving towards the liquid surface, the thickness of the two-dimensional cadmium sulfide film layer can be controlled by the interface of the two-phase system solvent, and the two-dimensional cadmium sulfide film layer with the nano-grade film thickness can be manufactured by breaking through the process capability of the prior art.
The present invention in a preferred example may be further configured to: in the process of evaporating the nonpolar solvent layer positioned on the upper layer, the current evaporation temperature is more than or equal to the boiling point of the nonpolar solvent layer positioned on the upper layer under the current air pressure, less than the boiling point of the polar solvent layer positioned on the lower layer under the current air pressure and less than the boiling point of the organic cadmium salt under the current air pressure, and specifically, the current evaporation temperature is between room temperature and 80 ℃.
By adopting the above preferred technical scheme, with the differential selection of the boiling point and the evaporation temperature under the current air pressure of the non-polar solvent layer, the evaporation of the non-polar solvent layer does not affect the evaporation of the polar solvent layer, the polar solvent layer can select pure water or other relatively low-temperature polar solvents, and the whole evaporation operation can meet the mass production category with low industrial cost.
The present invention in a preferred example may be further configured to: the organic cadmium salt solution comprises fatty acid cadmium salt and a pre-dissolved nonpolar solvent, the length of a carbon chain of a fatty acid group is 4-30, and the number of unsaturated bonds is 0-28.
By adopting the preferred technical scheme, two-stage operation of mixing the organic cadmium salt in the nonpolar solvent layer from pre-dissolving to complete dissolving is established by utilizing the specific composition selection of the organic cadmium salt solution, so that the organic cadmium salt can be pre-dissolved in the pre-dissolved nonpolar solvent to facilitate the mixing of the organic cadmium salt in the nonpolar solvent layer, the carbon chain length of the fatty acid group can establish a larger hydrophobic group and limit the upper limit of an unsaturated bond, and the proper carbon chain length of the fatty acid group can avoid the organic cadmium salt from being evaporated in the process of evaporating the nonpolar solvent layer and is favorable for orderly arranging the organic cadmium salt on the liquid surface of the polar solvent layer to form a film.
The present invention in a preferred example may be further configured to: the dosage of the organic cadmium salt solution is in positive relation with the liquid surface area of the polar solvent layer, and preferably meets (1-1000) multiplied by 1.6 multiplied by 10-8kg of cadmium salt of fatty acid dissolved in (20-40) × 10-6 m3Is pre-dissolved in a nonpolar solvent, and the volume is taken as nS multiplied by 5 multiplied by 10-10And C1, wherein n = 1-1000, S is the liquid surface area of the polar solvent layer, and c1 is the concentration of the organic cadmium salt solution.
By adopting the above preferred technical solution, the concentration and volume of the organic cadmium salt solution are defined by using the specific relation between the concentration and volume of the organic cadmium salt solution, and the concentration and volume of the organic cadmium salt solution do not depend on the volume in the non-polar solvent layer but depend on the liquid surface area of the non-polar solvent layer, so that the used volume in the non-polar solvent layer can be more flexibly increased to ensure the complete dissolution of the organic cadmium salt in the parameter setting before the preparation.
The present invention in a preferred example may be further configured to: the sulfur precursor solution comprises (NH)4）2S or/and Na2S soluble sulfur-containing aqueous solution and pre-dissolved polar solvent.
By adopting the preferable technical scheme, two-stage operation of pre-dissolving the sulfur precursor to completely dissolving and mixing the sulfur precursor in the polar solvent layer is established by utilizing the specific composition selection of the sulfur precursor solution, so that the sulfur precursor can be pre-dissolved in the pre-dissolved polar solvent, and the sulfur precursor can be conveniently mixed into the polar solvent layer.
The present invention in a preferred example may be further configured to: the dosage of the sulfur precursor solution and the dosage of the organic cadmium salt solution are in a positive relationship, and preferably meet (1-1000) multiplied by 2 multiplied by 10-11 m3(NH) at a concentration of 8wt.%4）2S or/and Na2S soluble sulfur-containing aqueous solution is dissolved in (20-40) x 10-6 m3And taking the volume of 2n multiplied by 10-8 m3The sulfur precursor solution of (a) is dissolved into the polar solvent layer located at the lower layer.
By adopting the above preferred technical solution, the concentration and volume of the sulfur precursor solution may not depend on the volume in the polar solvent layer but on the usage amount of the organic cadmium salt in the organic cadmium salt solution by utilizing the specific relationship ratio of the concentration and volume of the sulfur precursor solution, so that the usage volume in the polar solvent layer may be more flexibly increased to ensure complete dissolution of the sulfur precursor in the parameter setting before manufacturing.
The present invention in a preferred example may be further configured to: the organic cadmium salt has a hydrophobic group and is embossed on the liquid surface of the polar solvent layer after the non-polar solvent layer is evaporated, or/and the organic cadmium salt has a hydrophilic group and is floated on the liquid surface of the polar solvent layer after the non-polar solvent layer is evaporated.
By adopting the preferable technical scheme, the organic cadmium salt is provided with the hydrophobic group or/and the hydrophilic group, so that the organic cadmium salt is gathered into the film and floats on the liquid level of the polar solvent layer, and cadmium ions at the bottom of the organic cadmium salt can attract sulfur ions in the polar solvent layer to enrich the liquid level, thereby facilitating the generation of the nano-grade CdS film layer.
The present invention in a preferred example may be further configured to: in the step of adhering the two-dimensional cadmium sulfide film layer on the surface of the substrate, the substrate is vertically inserted into the polar solvent layer and then slowly tilted and lifted up, so that the two-dimensional cadmium sulfide film layer adhered on the substrate is obtained.
By adopting the above preferred technical scheme, a specific implementation scheme that the two-dimensional cadmium sulfide film layer is attached to the substrate can be provided by utilizing the vertical insertion of the substrate and then slowly inclining and lifting.
The present invention in a preferred example may be further configured to: the organic cadmium salt is selected from one of cadmium oleate, cadmium elaeate, cadmium stearate, cadmium palmitoleate, cadmium arachidonic acid, cadmium eicosapentaenoic acid, cadmium docosapentaenoic acid and cadmium laurate, and the nonpolar solvent layer is selected from one of toluene and homologues thereof, acetone and homologues thereof, chloroform and analogues thereof and n-hexane which has a specific gravity smaller than that of the polar solvent layer; the polar solvent layer is selected from water or amides.
By adopting the preferable technical scheme, the specific range limitation of the organic cadmium salt, the nonpolar solvent layer and the polar solvent layer is utilized, the two-phase system solvent with the polar solvent layer at the lower layer and the nonpolar solvent layer at the upper layer can be realized, and the specific realization that the organic cadmium salt solution can be dissolved in the nonpolar solvent layer is obtained.
The present invention in a preferred example may be further configured to: the method further comprises the steps of: after the organic cadmium salt solution is dissolved and before the step of evaporating the nonpolar solvent layer positioned on the upper layer, the two-phase system solvent is kept standing for waiting to clearly separate the nonpolar solvent layer and the polar solvent layer, and the step of evaporating the nonpolar solvent layer positioned on the upper layer comprises the following steps: the method comprises the steps of completely volatilizing the nonpolar solvent layer, providing standing time for generating a film layer for 1-36 hours, and carrying out the step of dissolving a sulfur precursor solution into the polar solvent layer positioned on the lower layer after the step of completely volatilizing the nonpolar solvent layer and before the standing step for generating the film layer, or carrying out the step of dissolving the organic cadmium salt solution into the nonpolar solvent layer positioned on the upper layer after the step of completely volatilizing the nonpolar solvent layer.
By adopting the preferable technical scheme, the immiscible interface of the nonpolar solvent layer and the polar solvent layer is clearly separated by using the execution time of the step of standing and waiting the two-phase system solvent, and meanwhile, the sulfur ions of the sulfur precursor solution move and are enriched towards the liquid surface of the polar solvent layer by using the execution time of the step of completely volatilizing the nonpolar solvent layer and dissolving the sulfur precursor solution into the polar solvent layer positioned at the lower layer.
The other main purpose of the invention is realized by the following technical scheme:
the method for forming two-dimensional cadmium sulfide on a substrate in a large area according to any of the above technical schemes.
Other objects of the present invention are to provide a nano-plate structure for photocatalytic hydrolysis hydrogen production, comprising: a two-dimensional cadmium sulfide structure is formed on a substrate in a large area according to any one of the above technical schemes.
In summary, the invention includes at least one of the following beneficial technical effects:
1. preparing a large-area two-dimensional cadmium sulfide film layer on any substrate at low cost;
2. the two-dimensional cadmium sulfide film layer has an ultrathin nanometer grade;
3. the method replaces the conventional hydrothermal method and other liquid phase methods to prepare a large-area ultrathin two-dimensional CdS nano material, and expands the application of the CdS material in the photocatalytic hydrolysis hydrogen production industry;
4. in the generation process of the two-dimensional cadmium sulfide film layer, the nonpolar solvent layer and the polar solvent layer do not participate in the reaction, and can be recycled, so that the manufacturing cost is reduced.
Drawings
FIG. 1 is a schematic flow chart of a method for forming two-dimensional cadmium sulfide on a substrate in a large area according to a preferred embodiment of the invention;
FIGS. 2A-2H are schematic component views illustrating steps in a preferred embodiment of the invention;
FIG. 3 is a partially enlarged view showing the organic cadmium salt integrated film floating on the liquid surface of the polar solvent layer after the evaporation step in accordance with one preferred embodiment of the present invention;
FIG. 4 is one of the results of the morphological characterization of the target product using Atomic Force Microscopy (AFM);
FIG. 5 is one of the results of a Scanning Electron Microscope (SEM) characterization of the target product produced, with the lighter colored upper right portion being two-dimensional hexagonal phase cadmium sulfide;
fig. 6 is a metallographic microscope photograph of the target product, and the darker part of the upper half section is two-dimensional hexagonal cadmium sulfide.
The reference signs are 10, organic cadmium salt solution, 11, organic cadmium salt, 12, hydrophobic group, 13, hydrophilic group, 20, two-phase system solvent, 21, nonpolar solvent layer, 22, polar solvent layer, 23, liquid level, 30, sulfur precursor solution, 40, two-dimensional cadmium sulfide film layer, 50 and substrate.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, other embodiments obtained by persons of ordinary skill in the art with the understanding of the inventive concept of the present invention are within the scope of the present invention.
It should be noted that, if directional indications (such as up, down, left, right, front, and back … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indications are changed accordingly.
In order to facilitate understanding of the technical solution of the present invention, the method and structure for forming two-dimensional cadmium sulfide on a substrate in a large area according to the present invention will be described in further detail below, but the present invention is not limited to the scope of the present invention.
The method and structure for forming two-dimensional cadmium sulfide on a substrate in a large area according to the present invention will be described in further detail below, but should not limit the scope of the present invention. FIG. 1 is a schematic flow chart of a method for forming two-dimensional cadmium sulfide on a substrate in a large area according to a first preferred embodiment of the invention, and FIGS. 2A to 2H are schematic component diagrams of steps according to the first preferred embodiment of the invention.
Referring to fig. 1, a method for forming two-dimensional cadmium sulfide on a substrate in a large area is disclosed in an embodiment of the present invention, which includes the following steps:
step S1 relates to preparing the organic cadmium salt solution, and in one example, referring to fig. 2A, the organic cadmium salt solution 10 is prepared in a smaller container.
Step S2 relates to providing the two-phase system solvent, in an example, please refer to fig. 2B, in a larger container, providing the two-phase system solvent 20, wherein the upper layer of the two-phase system solvent 20 is the non-polar solvent layer 21, and the lower layer is the polar solvent layer 22.
In step S3, regarding the solution of organic cadmium salt dissolving into the non-polar solvent layer on the upper layer, in an example, please refer to fig. 2C, the solution of organic cadmium salt 10 dissolving into the non-polar solvent layer 21 on the upper layer, and the organic cadmium salt of the solution of organic cadmium salt 10 gathering at the interface between the non-polar solvent layer 21 and the polar solvent layer 22.
In step S4, the sulfur precursor solution is dissolved in the non-polar solvent layer located at the lower layer, and in an example, please refer to fig. 2D, the sulfur precursor solution 30 is dissolved in the polar solvent layer 22 located at the lower layer.
Step S5 relates to evaporating the nonpolar solvent layer to generate a two-dimensional cadmium sulfide film on the liquid surface of the polar solvent layer, in an example, please refer to fig. 2E and fig. 2F in combination, the nonpolar solvent layer 21 on the upper layer is evaporated, so that the organic cadmium salt at the interface is gathered into a film as the volume of the nonpolar solvent layer 21 decreases, floats on the liquid surface of the polar solvent layer 22, and reacts with the sulfur ions in the polar solvent layer 22 to generate the two-dimensional cadmium sulfide film 40. A morphology in which the organic cadmium salt 11 coalesces into a film and floats on the surface of the polar solvent layer 22 can be seen in FIG. 3.
In step S6, the two-dimensional cadmium sulfide film layer 40 is adhered to the surface of the substrate 50, in an example, please refer to fig. 2G and fig. 2H in combination.
The implementation principle of the embodiment is as follows: as shown in fig. 3, the two-dimensional cadmium sulfide film layer 40 is formed by evaporating the nonpolar solvent layer 21 to gradually make the organic cadmium salt 11 gather into a film and float on the liquid surface 23 of the polar solvent layer 22 and react with the sulfur ions in the polar solvent layer 22, the two-dimensional cadmium sulfide film layer 40 can be attached to the surface of the substrate 50 in a large area and can also reach a nano-scale (below ten nano-scale) film thickness, the process temperature of the main steps is the upper limit of the boiling point of the polar solvent layer 22, the low-temperature manufacturing can be achieved, and the process qualification state can be easily identified.
It is particularly noted that the present invention is not limited to the execution sequence of the dissolving step S4 of the sulfur precursor solution 30, and may be executed between the steps S3 and S5, before the step S3, or in the step S5.
Regarding the possible thickness of the two-dimensional cadmium sulfide film layer 40 of step S5, in a preferred example, the thickness of the two-dimensional cadmium sulfide film layer 40 is less than 10 nanometers (nm), preferably, the thickness of the two-dimensional cadmium sulfide film layer 40 is between 0.5 and 3.0 nanometers, and more preferably, the thickness of the two-dimensional cadmium sulfide film layer 40 is between 1.0 and 1.2 nanometers. It is understood that the formation reaction of the two-dimensional cadmium sulfide film layer 40 is at the liquid level 23 of the polar solvent layer 22, and an ultra-thin film thickness morphology can be achieved. Therefore, by gradually aggregating the organic cadmium salt 11 into a film when the non-polar solvent layer 21 evaporates, floating on the liquid surface 23 of the polar solvent layer 22, and reacting with the sulfur ions moving toward the liquid surface 23, the thickness of the two-dimensional cadmium sulfide film layer 40 can be controlled by the interface of the two-phase system solvent 20, and the two-dimensional cadmium sulfide film layer 40 with a nano-scale film thickness can be manufactured by breaking through the process capability of the prior art.
Regarding possible compositions of the organic cadmium salt solution 10 in step S1, in a preferred example, the organic cadmium salt solution 10 includes a fatty acid cadmium salt and a pre-dissolved nonpolar solvent, the carbon chain length of the fatty acid group is 4-30, and the number of unsaturated bonds is 0-28. Therefore, by selecting the specific composition of the organic cadmium salt solution 10, a two-stage operation of mixing the organic cadmium salt 11 in the non-polar solvent layer 21 from pre-dissolution to complete dissolution is established, so that the organic cadmium salt 11 can be pre-dissolved in the pre-dissolved non-polar solvent to facilitate the mixing of the organic cadmium salt 11 in the non-polar solvent layer 21, and the carbon chain length of the fatty acid group can establish a larger hydrophobic group 12 and limit the upper limit of unsaturated bonds, and the proper carbon chain length of the fatty acid group can avoid the organic cadmium salt 11 from being evaporated during the evaporation of the non-polar solvent layer 21 and facilitate the ordered arrangement of the organic cadmium salt 11 on the liquid surface 23 of the polar solvent layer 22 to form a film.
Regarding possible material choices of the organic cadmium salt solution 11 and the two-phase system solvent 20 in steps S1 and S2, in a preferred example, the organic cadmium salt solution 11 includes one of cadmium oleate, cadmium elaeate, cadmium stearate, cadmium palmitoleate, cadmium arachidonic acid, cadmium eicosapentaenoic acid, cadmium docosapentaenoic acid and cadmium laurate, and the non-polar solvent layer 21 includes one or more of toluene and its homologues, acetone and its homologues, chloroform and its analogues, and a combination of non-polar solvents having a specific gravity smaller than that of the polar solvent layer 22; the polar solvent layer 22 is selected from water or amides. Therefore, with the specific range limitations of the organic cadmium salt 11, the nonpolar solvent layer 21, and the polar solvent layer 22, the two-phase system solvent 20 with the polar solvent layer 22 at the lower layer and the nonpolar solvent layer 21 at the upper layer can be realized, and a specific realization that the organic cadmium salt solution 10 can be dissolved into the nonpolar solvent layer 21 is obtained.
Regarding the possible addition amount of the organic cadmium salt solution 10 in step S3, in a preferred example, the amount of the organic cadmium salt 11 in the organic cadmium salt solution 10 is in a positive relationship with the area of the liquid surface 23 of the polar solvent layer 22, and preferably satisfies (1-1000). times.1.6.10 times-8kg of cadmium salt of fatty acid dissolved in (20-40) × 10-6 m3Is pre-dissolved in a nonpolar solvent, and the volume is taken as nS multiplied by 5 multiplied by 10-10And C1, wherein n = 1-1000, S is the area of the liquid surface 23 of the polar solvent layer 22, and c1 is the concentration of the organic cadmium salt solution 10. Therefore, the concentration and volume of the organic cadmium salt solution 10 are not determined by the volume in the non-polar solvent layer 21 but by the area of the liquid surface 23 of the non-polar solvent layer 21, which is defined by the specific relationship between the concentration and volume of the organic cadmium salt solution 10, so that the used volume in the non-polar solvent layer 21 can be more flexibly increased to ensure the complete dissolution of the organic cadmium salt 11 in the pre-manufacturing parameter setting.
Regarding possible compositions of the sulfur precursor solution 30 in step S4, in a preferred example, the sulfur precursor solution 30 includes (NH)4）2S or-With Na2S soluble sulfur-containing aqueous solution and pre-dissolved polar solvent. Therefore, by selecting a specific composition of the sulfur precursor solution 30, a two-stage operation of pre-dissolving the sulfur precursor into the polar solvent layer 22 to completely dissolve the sulfur precursor is established, so that the sulfur precursor can be pre-dissolved in the pre-dissolved polar solvent to facilitate the sulfur precursor to be mixed into the polar solvent layer 22.
Regarding the possible addition amount of the sulfur precursor solution 30 in the step S4, in a preferred example, the usage amount of the sulfur precursor solution 30 is in a positive relationship with the usage amount of the organic cadmium salt 11 of the organic cadmium salt solution 10, and preferably satisfies (1-1000). times.2 × 10-11 m3(NH) at a concentration of 8wt.%4）2S or/and Na2S soluble sulfur-containing aqueous solution is dissolved in (20-40) x 10-6 m3And taking the volume of 2n multiplied by 10-8 m3The sulfur precursor solution 30 is dissolved into the polar solvent layer 22 located below. Therefore, with the specific relationship between the concentration and the volume of the sulfur precursor solution 30, the concentration and the volume of the sulfur precursor solution 30 may not depend on the volume of the polar solvent layer 22 but on the amount of the organic cadmium salt 11 of the organic cadmium salt solution 10, so that the volume of the polar solvent layer 22 can be more flexibly increased to ensure the complete dissolution of the sulfur precursor in the pre-fabrication parameter setting.
Regarding one possible evaporation condition of step S5, in a preferred example, during the evaporation of the nonpolar solvent layer 21 located on the upper layer, the current evaporation temperature is greater than or equal to the boiling point of the nonpolar solvent layer 21 located on the upper layer under the current atmospheric pressure, less than the boiling point of the polar solvent layer 22 located on the lower layer under the current atmospheric pressure, and less than the boiling point of the organic cadmium salt 11 under the current atmospheric pressure, and specifically, the current evaporation temperature is between room temperature and 80 ℃. Therefore, by using the difference between the boiling point and the evaporation temperature of the non-polar solvent layer 21 under the current atmospheric pressure, the evaporation of the non-polar solvent layer 21 does not affect the evaporation of the polar solvent layer 22, and the polar solvent layer 22 can be pure water or other relatively low-temperature polar solvents, so that the whole evaporation operation can be suitable for the mass production category with low industrial cost.
Regarding the possible manner of making the organic cadmium salt 11 gather into a film and float in step S5, in a preferred example, referring to fig. 3 again, the organic cadmium salt 11 has hydrophobic groups 12 that are embossed on the liquid surface 23 of the polar solvent layer 22 after evaporating the non-polar solvent layer 21, or/and the organic cadmium salt 11 has hydrophilic groups 13 that float on the liquid surface 23 of the polar solvent layer 22 after evaporating the non-polar solvent layer 21. Therefore, the organic cadmium salt 11 having the hydrophobic group 12 or/and the hydrophilic group 13 can float on the liquid surface 23 of the polar solvent layer 22, and the cadmium ions at the bottom can attract the sulfur ions in the polar solvent layer 22 to enrich the liquid surface 23, so as to facilitate the generation of the nano-grade CdS film layer.
Regarding one possible adhering manner of the two-dimensional cadmium sulfide film layer 40 in step S6, in a preferred example, in the step of adhering the two-dimensional cadmium sulfide film layer 40 on the surface of the substrate 50, the substrate 50 is vertically inserted into the polar solvent layer 22 and then slowly tilted up to obtain the two-dimensional cadmium sulfide film layer 40 adhered on the substrate 50. Thus, using a vertical insertion of the substrate 50 followed by a slow tilt lift can provide a specific implementation of the two-dimensional cadmium sulfide film layer 40 attached to the substrate 50.
With regard to the possible order of the additional steps and the main steps of the present invention, in a particularly preferred example, the forming method further comprises the steps of: after the step S3 of dissolving the organic cadmium salt solution and before the step S5 of evaporating the nonpolar solvent layer 21 located at the upper layer, the two-phase system solvent 20 is left to stand for clearly separating the nonpolar solvent layer 21 from the polar solvent layer 22, and in the step S5 of evaporating the nonpolar solvent layer 21 located at the upper layer, the method includes: the method comprises the steps of completely volatilizing the nonpolar solvent layer 21, providing a standing time for film layer generation of 1-36 hours, and dissolving the sulfur precursor solution 30 into the polar solvent layer 22 at the lower layer in step S4 after the next step of completely volatilizing the nonpolar solvent layer 21 at the front stage of step S5 and before the next step of film layer generation at the rear stage of step S5, or step S4 can be performed after the step S3 of dissolving the organic cadmium salt solution 10 into the nonpolar solvent layer 21 at the upper layer and before the next step of completely volatilizing the nonpolar solvent layer 21 at the front stage of step S5. Therefore, the execution timing of the step of standing and waiting for the two-phase system solvent 20 is utilized to clearly separate the immiscible interface between the nonpolar solvent layer 21 and the polar solvent layer 22, and meanwhile, the execution timing of the step of completely volatilizing the nonpolar solvent layer 21 and dissolving the sulfur precursor solution 30 into the polar solvent layer 22 positioned at the lower layer is utilized to realize the moving and enrichment of the sulfur ions of the sulfur precursor solution 30 to the liquid surface 23 of the polar solvent layer 22.
In addition, the second embodiment of the present invention also provides a method for forming two-dimensional cadmium sulfide on a substrate in a large area according to any of the above-mentioned technical solutions. The third embodiment of the invention discloses a nano plate-shaped structure for preparing hydrogen by photocatalytic hydrolysis, which comprises: a two-dimensional cadmium sulfide structure is formed on a substrate in a large area according to any one of the above technical schemes.
A fourth embodiment of the invention provides a low-cost method for preparing hexagonal-phase two-dimensional cadmium sulfide on an arbitrary substrate, comprising a wet chemical method, in particular the main steps of:
step 1, weighing (1-1000) × 1.6 × 10-8kg of cadmium salt of fatty acid dissolved in (20-40) × 10-6 m3To obtain a solution of a cadmium salt of fatty acid having a concentration of c 1. The carbon chain length of the fatty acid is 4-30, and the number of unsaturated bonds is 0-28;
step 2, adding a polar solvent with a volume of V (polar) to the bottom area of S (unit: m)2) A vessel with a volume V, then a less dense and volatile non-polar solvent with a volume V (non) is added above the solvent. The upper layer of the obtained two-phase system is a non-polar solvent, and the lower layer is a polar solvent, wherein V (polar) < V, V (non) < V, and V (polar) + V (non) < V;
step 3, adding a volume of 2n multiplied by 10 into the nonpolar solvent above the two-phase system-8 m3The prepared fatty acid cadmium solution is characterized in that n = 1-1000;
step 4, multiplying (1-1000) x 2 x 10-11 m3Soluble aqueous sulfur-containing solution ((NH)4)2S, 8 wt.%) is dissolved in (20-40). times.10-6 m3In the polar solvent of (2), a sulfur precursor solution is prepared. After 1 hour from step 3, 2 n.times.10 was added-8 m3(n = 1-1000) injecting the prepared sulfur precursor solution into the lower-layer polar solvent of the two-phase system in the step 2. Then placing the obtained two-phase solution system in an oven with the temperature of T for evaporation, wherein T = room temperature-80 ℃;
and 5, after 1-36 hours, after the nonpolar solvent on the upper layer of the two-phase solution system in the step 3 is completely volatilized, vertically inserting the substrate into the water surface, and slowly and obliquely lifting to obtain the two-dimensional cadmium sulfide attached to the substrate.
The uniqueness of the low-cost preparation method of large-area two-dimensional cadmium sulfide on any substrate is that:
the ratio of (1 to 1000) × 1.6 × 10-8kg of cadmium salt of fatty acid dissolved in (20-40) × 10-6 m3To obtain a solution of a cadmium salt of fatty acid having a concentration of c 1. The carbon chain length of the fatty acid is 4-30, and the number of unsaturated bonds is 0-28; the concentration of the precursor is controlled, and the target product is a single-layer or few-layer two-dimensional material.
In an area of S (unit: m)2) Adding a polar solvent with the volume of V (polar) into a container with the volume of V, adding a non-polar solvent with the volume of V (non) which is relatively low in density and volatile above the polar solvent to obtain a two-phase system with an upper layer of the non-polar solvent and a lower layer of the polar solvent, wherein V (polar) is less than V, V (non) is less than V, and V (polar) + V (non) is less than or equal to V; not only the non-polar solvent is easy to volatilize, but also the preparation process is easier to implement and flexible.
Adding a volume of 2n × 10 into the nonpolar solvent above the two-phase system-8 m3The prepared fatty acid cadmium solution is characterized in that n = 1-1000; the amount of the precursor is controlled, and the target product is a single-layer or few-layer two-dimensional material.
Putting the obtained two-phase solution system in an oven with the temperature of T for evaporation, wherein T = room temperature-80 ℃; the temperature is increased, so that the preparation time is shortened, and the method is suitable for industrial production.
The ratio of (1 to 1000) × 2 × 10-11 m3Soluble sulfur-containing aqueous solution ((NH 4) 2S, 8 wt.%) is dissolved in (20-40). times.10-6 m3In the polar solvent of (2), a sulfur precursor solution is prepared. After 1 hour from step 3, 2 n.times.10 was added-8m3 (n = 1-1000), and injecting the prepared sulfur precursor solution into the lower-layer polar solvent of the two-phase system in the step 2; also, the concentration of the precursor is controlled, ensuring that the target product is a single layer or few layers of two-dimensional material.
After 1-36 hours, vertically inserting the substrate into the water surface, and slowly and obliquely lifting to obtain two-dimensional cadmium sulfide attached to the substrate; this two-dimensional material transfer strategy ensures that two-dimensional material grown on the liquid surface can be transferred for use on any substrate.
The unique effects of the preparation method of the embodiment compared with the prior art are as follows:
firstly, the prepared target product is respectively characterized by using an atomic force microscope and a metallographic microscope, and the result shows that the target product is large-area two-dimensional cadmium sulfide with good uniformity and thickness of 1.0-1.2 nm.
Secondly, the preparation method is simple, convenient, rapid and efficient, and not only is the large-area two-dimensional hexagonal phase cadmium sulfide prepared; the band gap is more suitable; the method also has the characteristics of time saving, energy saving, environmental protection, low preparation cost and easy large-scale industrial production: the required raw materials are all common raw materials for industrial production, namely, the fatty acid cadmium used as the raw material is of industrial grade, and the used polar solvent and the used nonpolar solvent are also of industrial grade, are easy to obtain and have low price; a great deal of profit can be obtained by using a very small amount of industrial raw materials, 1 to 5 grams of industrial fatty acid cadmium can be used for preparing 100 square meters of two-dimensional cadmium sulfide according to the general standard of industrial production, and the method has great economic benefit.
Fig. 4 is one of the results of the morphological characterization of the target product using Atomic Force Microscopy (AFM). AFM results show that the product has obvious tearing phenomenon and less surface impurities, the target product is a uniform two-dimensional material with the thickness of 1.0-1.2nm, FIG. 5 is one of characterization results of a Scanning Electron Microscope (SEM) used for the prepared target product, the part with lighter color at the upper right side is two-dimensional hexagonal cadmium sulfide, FIG. 6 is a metallographic microscope photo of the target product, and the part with darker color at the upper half section is two-dimensional hexagonal cadmium sulfide. From the results, the product has less impurities and the surface of the film is uniform and flat. Fig. 4, 5 and 6 show that the target product is a uniform large-area two-dimensional material.
The following six experimental examples are specifically illustrated, first commercially available or prepared by conventional methods: the cadmium fatty acid used as a cadmium source has a carbon chain length of 4-30 and the number of unsaturated bonds of 0-28; soluble sulfur salts as reactants, polar solvents to provide a reaction interface, and non-polar solvents that are less dense and more volatile than the polar solvents. The raw materials are all industrial grade. As a target substrate for the two-dimensional material after transfer from the liquid surface.
The specific procedure for the preparation of test example 1 was:
step 1, the (1-1000) × 1.6 × 10−8kg of cadmium salt of fatty acid dissolved in (20-40) × 10−6m3To obtain a solution of a cadmium salt of fatty acid having a concentration of c 1. Wherein 1000 is selected from (1-1000), 20 is selected from (20-40), and c1=0.8kg/m3The fatty acid cadmium is cadmium oleate, and the nonpolar solvent is toluene.
Step 2, in the area S (unit: m)2) In a vessel having a volume V, a polar solvent having a volume V (polar) is added. Adding a non-polar solvent with smaller density and volatility and volume V (non) above the polar solvent. The upper layer is a non-polar solvent and the lower layer is a polar solvent. Wherein the polar solvent is water, the nonpolar solvent is toluene, V (polar) =50% V, and V (non) =20% V.
Step 3, adding a volume of 2n multiplied by 10 into the nonpolar solvent of the two-phase upper system−8m3 (n = 1-1000) the prepared fatty acid cadmium solution, wherein n = 2.
Step 4, multiplying (1-1000) x 2 x 10−8m3Soluble aqueous sulfur-containing solution ((NH)4)2S，8wt.%） Dissolved in (20-40) × 10−6m3In the polar solvent of (2), a sulfur precursor solution is prepared. After 1 hour from step 3, 2 n.times.10 was added−8m3(n = 1-1000) injecting the prepared sulfur precursor solution into the lower-layer polar solvent of the two-phase system in the step 2. The resulting biphasic solution system was then placed in an oven at temperature T for evaporation, where T = room temperature. Wherein the polar solvent is water, the nonpolar solvent is toluene, the soluble sulfur salt is an ammonium sulfide aqueous solution, 1 is taken from (1-1000), 20 is taken from (20-40), and n = 2.
And 5, after 1-36 hours, vertically inserting the substrate into the water surface, and slowly and obliquely lifting to obtain the two-dimensional cadmium sulfide attached to the substrate. Wherein 1 to 36 hours is 30 hours. Large-area two-dimensional hexagonal phase cadmium sulfide similar to that shown in fig. 4, 5 and 6 was prepared.
The specific steps for the preparation of test example 2 were:
step 1, weighing (1-1000) × 1.6 × 10−8kg of cadmium salt of fatty acid dissolved in (20-40) × 10−6m3To obtain a solution of a cadmium salt of fatty acid having a concentration of c 1. Wherein 1000 is selected from (1-1000), 20 is selected from (20-40), and c1=0.8kg/m3The fatty acid cadmium is cadmium oleate, and the nonpolar solvent is toluene.
Step 2, in the area S (unit: m)2) In a vessel having a volume V, a polar solvent having a volume V (polar) is added. Adding a non-polar solvent with smaller density and volatility and volume V (non) above the polar solvent. The upper layer is a non-polar solvent and the lower layer is a polar solvent. Wherein the polar solvent is water, the nonpolar solvent is toluene, V (polar) =40% V, and V (non) =40% V.
Step 3, adding a volume of 2n multiplied by 10 into the nonpolar solvent of the two-phase upper system−8m3(n = 1-1000) the prepared fatty acid cadmium solution, wherein n = 1-1000. Where n = 2.
Step 4, multiplying (1-1000) x 2 x 10−8m3Soluble aqueous sulfur-containing solution ((NH)4)2S, 8 wt.%) is dissolved in (20-40). times.10−6m3In a polar solvent of (2), before preparation of sulfurAnd (4) a body-driving solution. After 1 hour from step 3, 2 n.times.10 was added−8m3(n = 1-1000) injecting the prepared sulfur precursor solution into the lower-layer polar solvent of the two-phase system in the step 2. Wherein 1 is selected from (1-1000), 20 is selected from (20-40), and n = 10. The polar solvent was water, the non-polar solvent was toluene, and the soluble sulfur salt was aqueous ammonium sulfide (8 wt.%). The resulting biphasic solution system was then placed in an oven at temperature T for evaporation, where T =60 ℃.
And 5, after 1-36 hours, vertically inserting the substrate into the water surface, and slowly and obliquely lifting to obtain the two-dimensional cadmium sulfide attached to the substrate. Wherein 1 to 36 hours is 6 hours. Large-area two-dimensional hexagonal phase cadmium sulfide similar to that shown in fig. 4, 5 and 6 was prepared.
The specific procedure for the preparation of test example 3 was:
step 1, weighing (1-1000) × 1.6 × 10−8kg of cadmium salt of fatty acid dissolved in (20-40) × 10−6m3To obtain a solution of a cadmium salt of fatty acid having a concentration of c 1. Wherein 1000 is taken from (1-1000), 20 is taken from (20-40), c1=0.8kg/m 3, cadmium stearate is fatty acid cadmium, and chloroform is used as a nonpolar solvent.
Step 2, in the area S (unit: m)2) In a vessel having a volume V, a polar solvent having a volume V (polar) is added. Adding a non-polar solvent with smaller density and volatility and volume V (non) above the polar solvent. The upper layer is a non-polar solvent and the lower layer is a polar solvent. Wherein V (polar) =60% V, V (non) =30% V, the polar solvent is water, and the non-polar solvent is chloroform.
Step 3, adding a volume of 2n multiplied by 10 into the nonpolar solvent of the two-phase upper system−8m3(n = 1-1000) the prepared fatty acid cadmium solution, wherein n = 1-1000. Where n = 100.
Step 4, multiplying (1-1000) x 5.7 x 10−6kg soluble sulfur salt dissolved in (20-40) x 10−6m3In the polar solvent of (2), a sulfur precursor solution is prepared. After 1 hour from step 3, 2 n.times.10 was added−8m3(n = 1-1000) injecting the prepared sulfur precursor solution intoIn the lower polar solvent of the two-phase system in the step 2. Wherein the polar solvent is water, the nonpolar solvent is chloroform, the soluble sulfur salt is sodium sulfide nonahydrate, 100 is taken from (1-1000), 20 is taken from (20-40), and n = 10. The resulting biphasic solution system was evaporated in an oven at temperature T, where T =50 ℃.
And 5, after 1-36 hours, vertically inserting the substrate into the water surface, and slowly and obliquely lifting to obtain the two-dimensional cadmium sulfide attached to the substrate. Wherein 1 to 36 hours is 3 hours. Large-area two-dimensional hexagonal phase cadmium sulfide similar to that shown in fig. 4, 5 and 6 was prepared.
The specific procedure for the preparation of test example 4 was: step 1, weighing (1-1000) × 1.6 × 10−8kg of cadmium salt of fatty acid dissolved in (20-40) × 10−6m3To obtain a solution of a cadmium salt of fatty acid having a concentration of c 1. Wherein 1000 is taken as (1-1000), 20 is taken as (20-40), and c1=0.8kg/m3The fatty acid cadmium is cadmium palmitoleate, and the nonpolar solvent is acetone.
Step 2, in the area S (unit: m)2) In a vessel having a volume V, a polar solvent having a volume V (polar) is added. Adding a non-polar solvent with smaller density and volatility and volume V (non) above the polar solvent. The upper layer is a non-polar solvent and the lower layer is a polar solvent. Wherein the polar solvent is water, the nonpolar solvent is acetone, V (polar) =50% V, and V (non) =10% V.
Step 3, adding a volume of 2n multiplied by 10 into the nonpolar solvent of the two-phase upper system−8m3(n = 1-1000) a ready-made cadmium fatty acid solution, wherein n = 10.
Step 4, multiplying (1-1000) x 2 x 10−8m3Soluble aqueous sulfur-containing solution ((NH)4)2S, 8 wt.%) is dissolved in (20-40). times.10−6m3In the polar solvent of (2), a sulfur precursor solution is prepared. After 1 hour from step 3, 2 n.times.10 was added−8m3(n = 1-1000) injecting the prepared sulfur precursor solution into the lower-layer polar solvent of the two-phase system in the step 2. Wherein the polar solvent is water, the nonpolar solvent is chloroform, and the soluble sulfur salt isSodium sulfide nonahydrate, taking 1 from (1-1000), taking 20 from (20-40), and taking n = 100. The resulting biphasic solution system was evaporated in an oven at temperature T, where T =40 ℃.
And 5, after 1-36 hours, vertically inserting the substrate into the water surface, and slowly and obliquely lifting to obtain the two-dimensional cadmium sulfide attached to the substrate. Wherein 1 to 36 hours is 8 hours. Large-area two-dimensional hexagonal phase cadmium sulfide similar to that shown in fig. 4, 5 and 6 was prepared.
The specific procedure for the preparation of test example 5 was:
step 1, weighing (1-1000) × 1.6 × 10−8kg of cadmium salt of fatty acid dissolved in (20-40) × 10−6m3To obtain a solution of a cadmium salt of fatty acid having a concentration of c 1. Wherein 1000 is taken as (1-1000), 20 is taken as (20-40), and c1=0.8kg/m3The fatty acid cadmium is arachidonic acid cadmium, and the nonpolar solvent is n-hexane.
Step 2, in the area S (unit: m)2) In a vessel having a volume V, a polar solvent having a volume V (polar) is added. Adding a non-polar solvent with smaller density and volatility and volume V (non) above the polar solvent. The upper layer is a non-polar solvent and the lower layer is a polar solvent. Wherein the polar solvent is formamide, the nonpolar solvent is n-hexane, V (polar) =70% V, and V (non) =20% V.
Step 3, adding a volume of 2n multiplied by 10 into the nonpolar solvent of the two-phase upper system−8m3(n = 1-1000) a ready-made cadmium fatty acid solution, wherein n = 2.
Step 4, multiplying (1-1000) x 2 x 10−8m3Soluble aqueous sulfur-containing solution ((NH)4)2S, 8 wt.%) is dissolved in (20-40). times.10−6m3In the polar solvent of (2), a sulfur precursor solution is prepared. After 1 hour from step 3, 2 n.times.10 was added−8m3(n = 1-1000) injecting the prepared sulfur precursor solution into the lower-layer polar solvent of the two-phase system in the step 2. Wherein the polar solvent is formamide, the nonpolar solvent is n-hexane, the soluble sulfur salt is an ammonium sulfide aqueous solution, 1 is taken from (1-1000), 20 is taken from (20-40), and n = 1000. Will getThe resulting biphasic solution system was evaporated in an oven at temperature T, where T =60 ℃.
And 5, after 1-36 hours, vertically inserting the substrate into the water surface, and slowly and obliquely lifting to obtain the two-dimensional cadmium sulfide attached to the substrate. Wherein 1 to 36 hours is 2 hours. Large-area two-dimensional hexagonal phase cadmium sulfide similar to that shown in fig. 4, 5 and 6 was prepared.
In other experimental examples, cadmium fatty acid having a carbon chain length of 4 to 30 and a number of unsaturated bonds of 0 to 28, such as: cadmium eicosapentaenoic acid, cadmium docosapentaenoic acid or cadmium laurate as cadmium source, and the concentration c1 of cadmium fatty acid is selected from c1= 0.16kg/m3、c1 = 0.4kg/m3Or c1= 1.6kg/m3The polar solvent is selected from formamide, the nonpolar solvent is selected from n-hexane, the soluble sulfur salt is selected from ammonium sulfide aqueous solution or sodium sulfide and the like, S, V (polar), V (non), n, T, (1-1000) and any value meeting the requirements of actual production and the patent is taken for 1-36 hours, and the conditions of the operation of the test examples 1-5 are repeated, so that the large-area hexagonal-phase two-dimensional cadmium sulfide as shown in or similar to the figure 4, the figure 5 and the figure 6 is prepared.
The embodiments of the present invention are merely preferred embodiments for easy understanding or implementing of the technical solutions of the present invention, and not intended to limit the scope of the present invention, and all equivalent changes in structure, shape and principle of the present invention should be covered by the claims of the present invention.