Self-assembly, and manufacturing method thereof

Abstract

The present embodiment provides a self-assembly and a method for manufacturing the same, wherein two-dimensional nanosheets are joined edge to edge to form a hollow spherical shape.

Description

Technology Field

[0001] The present invention relates to a self-assembly and a method for manufacturing the same, and more specifically, to a hollow spherical 2D silica nanosheet self-assembly catalyst arranged edge-to-edge and a method for manufacturing the same. Background Technology

[0002] Similar to making molecules from atoms, if different nanoparticles are regulated to create distinct ensemble structures, advanced meso-scale materials with unique properties and applications can be produced.

[0003] Accordingly, tunable self-assembly of anisotropic nanoparticles (e.g., nanocubes, nanorods, tetrahedra, etc.) that exhibit arrangements along specific planes depending on the material's intrinsic inter-plane attraction and surface curvature, or charge distribution, is being studied.

[0004] However, most of these strategies utilize large surface areas, which suggests that selective induction between edges of anisotropic 2D nanosheets with edges a thickness of a few nanometers is very difficult.

[0005] Generally, strong van der Waals (vdW) forces between 2D infinite planar surfaces lead to enthalpy-favorable inter-plane stacking, which limits functional applicability based on the available surface area and exhibits characteristics similar to bulk-scale materials.

[0006] In other words, there are problems in that it is not easy to extend the possible 2D surface in self-assemblies, it is difficult to create flat or curved structures (scrolls, fibers, films, flower-shaped structures, etc.), and it is difficult to exhibit mechanical and chemical properties superior to those of individual components. The problem to be solved

[0007] In this embodiment, flat 2D silica nanosheets (2D-SiNS) are joined together in an edge-to-edge manner to obtain the required surface curvature and are intended to provide a self-assembled structure having a uniform size distribution. More specifically, the self-assembled structure is intended to be a hollow micron-sized shell (SA-SiMS) resembling a soccer ball, created through the unique edge-to-edge orientation linkage and self-assembly of 2D silica nanosheets.

[0008] In addition, we aim to provide a method for manufacturing a self-assembled body that can produce a single-layer hollow shell without the influence of additional organic linkers, surfactants, or emulsions and exhibits a high yield. means of solving the problem

[0009] A self-assembly according to one embodiment may be formed in the shape of a hollow sphere by joining two-dimensional nanosheets edge to edge.

[0010] In a self-assembly according to one embodiment, the two-dimensional nanosheet may include an electric double layer in the edge and face regions.

[0011] A self-assembly according to one embodiment may include a silica coating layer on the surface of the two-dimensional nanosheet.

[0012] A self-assembly according to one embodiment may have a silica coating layer comprising a crystal structure of a metal-electric double layer.

[0013] A self-assembly according to one embodiment may have a crystal structure of the metal electric double layer in which a metal hydroxide containing NiCo is encapsulated inside a silica coating layer.

[0014] A self-assembly according to one embodiment may have a thickness of 10.0 to 15.0 nm for the two-dimensional nanosheet.

[0015] A self-assembly according to one embodiment may have a silica coating layer with a thickness of 5 to 20 nm.

[0016] In a self-assembly according to one embodiment, the inner diameter of the self-assembly may be 0.5 to 5.0 μm.

[0017] In a self-assembly according to one embodiment, the surface area of ​​the self-assembly is 1 μm 2 to 10 μm 2 It could be.

[0018] In a self-assembly according to one embodiment, the connection between the edges may include a Si-O-Si covalent bond.

[0019] A self-assembly according to one embodiment may comprise 50 to 500 two-dimensional nanosheets.

[0020] A method for manufacturing a self-assembled body according to another embodiment comprises a step of preparing a two-dimensional nanosheet; and a step of encapsulating the two-dimensional nanosheet; wherein the encapsulation step of the two-dimensional nanosheet may be performed at 21 to 29°C for 5 to 30 hours to encapsulate a plurality of two-dimensional nanosheets.

[0021] A method for manufacturing a self-assembled body according to one embodiment may further include a step of introducing a solution containing a silica salt prior to the encapsulation step of a two-dimensional nanosheet.

[0022] In a method for manufacturing a self-assembly according to one embodiment, the two-dimensional nanosheet may have one or more selected from the group consisting of dodecyl sulfate, Ni metal, Co metal, and hydroxyl groups inserted therein.

[0023] A method for manufacturing a self-assembled body according to one embodiment may involve the encapsulation step of the two-dimensional nanosheet being performed in a pH range of 4.0 to 7.0. Effects of the invention

[0025] According to the present embodiment, the self-assembly exhibits high mechanical stability and can demonstrate a high conversion rate into synthesis gas. More specifically, it exhibits high-temperature mechanical stability compared to other assembly structures, which can facilitate access to the active site through enhanced bulk transport, enabling efficient diffusion of reactants and products during the dry reforming reaction of methane.

[0026] Furthermore, the self-assembly comprising a thin silica coating layer according to the present embodiment provides a restraining effect that effectively prevents the sintering and deactivation of the nano-catalyst. In addition, the microporous structure of the self-assembly promotes excellent heat transfer, thereby maintaining a uniform temperature distribution and preventing the formation of hot spots. Such excellent mechanical stress and high-temperature stability can ultimately lead to an extension of the catalyst lifespan.

[0027] Furthermore, as components of large self-assembled structures, two-dimensional nanosheets can exhibit unique properties such as high aspect ratio, abundant active sites, excellent charge transport, and mass diffusion.

[0028] Meanwhile, the method for manufacturing the above self-assembly can produce a single-layer hollow shell without the influence of additional organic linkers, surfactants, or emulsions, so it is economically superior and can show a high yield. Brief explanation of the drawing

[0029] Figure 1 shows a schematic diagram of the process of interlocking and self-assembling 2D-SiNS in an edge-to-edge orientation with a hollow micron-sized shell (SA-SiMS) such as a soccer ball. Figure 2 shows an image of M@SA-SiMS demonstrating high performance in a bed reactor for DRM response. FIG. 3 shows a low-field Scanning Electron Microscope (SEM) image of SA-SiMS and an Atomic Force Microscope (AFM) image (bottom left) of a single unit (2D-SiNS) for estimating the thickness of SA-SiMS in a self-assembled structure according to one embodiment. FIG. 4 shows a high-field SEM image of SA-SiMS in a self-assembled body according to one embodiment. FIG. 5 shows a low-field Transmission Electron Microscope (TEM) image of SA-SiMS and a single unit (2D-SiNS) image (bottom left) for visualizing individual thin 2D-SiNSs in a self-assembled structure according to one embodiment. FIG. 6 is a HAADF (High-angle annular dark field)-STEM (scanning transmission electron microscopy) image superimposed with SA-SiMS EDX line profiling showing the coexistence of Si, Ni, and Co elements in a hollow interior in a self-assembled structure according to one embodiment. Figure 7 shows SEM images and AFM images (top row) (i) and TEM images (bottom row) (ii) of 2D-SiNS for thickness estimation in a self-assembled body according to Comparative Example 1. FIG. 8 shows SEM images and AFM images (top row) (i) and TEM images (bottom row) (ii) of 2D-SiNS for thickness estimation in a self-assembled body according to Comparative Example 2. FIG. 9 shows SEM images and AFM images (top row) (i) and TEM images (bottom row) (ii) of 2D-SiNS for thickness estimation in a self-assembled body according to Comparative Example 3. FIG. 10 shows a graph of the thickness and side dimensions of a 2D-SiNS building unit according to the reaction temperature in a self-assembled structure according to one embodiment and a comparative example. Figure 11 shows a graph of surface charge measurements of 2D-SiNS synthesized in water at various temperatures. FIG. 12 shows an image investigating the mechanism of morphological evolution of SA-SiMS in a self-assembled body according to one embodiment. Figure 13 shows a graph of titration performed on 2D-SiNS. Figure 14 shows TEM images illustrating the assembly between 2D-SiNS and oppositely charged [(+)-AuNP] spherical nanoparticles at various pH values ​​in 2D-SiNS. Figure 15 shows a separation and deformation test graph measured at the center of the suspended portion of 2D-SiNS for each 2D-SiNS of different thicknesses synthesized at 23°C and 30°C. FIG. 16 shows an SEM image of SA-SiMS showing the reversible shrinkage of the entire structure in a water / ethanol system in a self-assembled structure according to one embodiment. FIG. 17 shows a differential volume graph with respect to pore size and a volume graph with respect to relative pressure for deriving the BET (Brunauer-Emmett-Teller) surface area of ​​SA-SiMS in a self-assembled body according to one embodiment. FIG. 18 shows an XRD graph of a self-assembled body according to one embodiment. FIG. 19 shows TEM and HAADF-STEM images of SA-SiMS after heat treatment at 500°C in an air atmosphere for a self-assembled body according to one embodiment. FIG. 20 shows TEM and HAADF-STEM images of SA-SiMS and elemental line profiling based on energy dispersive X-ray spectroscopy (EDX) after heat treatment at 500°C in an H2 / Ar atmosphere in a self-assembled body according to one embodiment. Figure 21 shows an image illustrating the DRM performance and morphological analysis of the catalyst after use through M@SA-SiMS. Specific details for implementing the invention

[0030] The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. As used in the specification, the meaning of "comprising" specifies certain characteristics, areas, integers, steps, actions, elements, and / or components, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and / or components.

[0031] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined.

[0032] Also, unless otherwise specified, % refers to weight %.

[0033] In this specification, the term “combination(s) of these” described in the Markush-type expression means one or more mixtures or combinations selected from the group consisting of the components described in the Markush-type expression, and means including any one or more selected from the group consisting of said components.

[0034] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below.

[0036] Self-assembly

[0037] To solve the aforementioned problems, it is necessary to develop advanced meso-scale materials with specific structures, hierarchical functions, and enhanced properties by precisely arranging nanoparticles and controlling their interactions to assemble them into distinct assembly structures.

[0038] In this embodiment, the aforementioned problems are solved by inventing a self-assembly that combines the edges of two-dimensional nanosheets. Specifically, the present invention can provide a self-assembly in which two-dimensional nanosheets are combined edge to edge to form a hollow spherical shape.

[0039] The above two-dimensional nanosheet may include an electric double layer in the edge and face regions.

[0040] More specifically, edge-to-edge coupling may be achieved through an electric double layer formed between two-dimensional nanosheets. The electric double layer can create electrical deflection in the edge and face regions and provide physical flexibility to individual 2D-SiNS.

[0041] The surface of the above two-dimensional nanosheet may include a silica coating layer.

[0042] The above silica coating layer can provide a restraining effect that effectively prevents the sintering and deactivation of the nano-catalyst.

[0043] The above silica coating layer may include a crystal structure of a metal-electric double layer.

[0044] The crystal structure of the above metal electric double layer may be such that a metal hydroxide containing NiCo is encapsulated inside a silica coating layer.

[0045] At this time, the surface electric double layer, i.e., the surface charge, can be determined according to the balance of the two materials (metal hydroxide and silica layer). Additionally, the NiCo-hydroxide may have a Brucite structure, and the surface silica layer may have an Amorphous structure.

[0046] By including the crystal structure of the above metal-electric double layer, high performance can be demonstrated in a reactor for dry reforming of methane reactions. Specifically, it can withstand high temperatures of 500 to 900°C for a long period of time of more than 100 hours and can show a high conversion rate into synthesis gas.

[0047] The thickness of the above two-dimensional nanosheet may be 10.0 to 15.0 nm, more specifically 11.0 nm to 13.0 nm.

[0048] By satisfying the above thickness range, the edges can meet well, allowing it to be formed into a hollow spherical self-assembly.

[0050] The thickness of the silica coating layer may be 0.1 to 10 nm, more specifically 0.5 nm to 5 nm.

[0051] By satisfying the above thickness range, a hollow spherical self-assembly can be formed. More specifically, it is possible to prevent the aggregation of small nanocrystals with catalytic activity, prevent coke formation, and ensure durability, thereby facilitating enhanced material transport. Furthermore, the physical flexibility depending on the thickness of the silica coating layer can play an important role in imparting the curvature required for the assembly process and completion.

[0053] The inner diameter of the self-assembly above may be 0.5 to 5.0 μm, more specifically 0.5 to 3.0 μm.

[0054] By satisfying the above internal diameter range, functional applicability can be enhanced based on the usable surface area. In other words, the possible 2D surface can be expanded, and unique and excellent mechanical and chemical properties can be exhibited. Furthermore, the hollow spherical self-assembly exhibits high mechanical stability even at high temperatures and can demonstrate excellent performance as a catalyst support for the dry reforming reaction of methane.

[0056] The surface area of ​​the above self-assembly is 1 μm 2 to 10 μm 2 , more specifically 3 μm 2 to 7 μm 2 It could be.

[0057] By satisfying the above surface area range, functional applicability can be enhanced based on the available surface area. In other words, the possible 2D surface can be expanded, and unique and excellent mechanical and chemical properties can be exhibited. Furthermore, the hollow spherical self-assembly exhibits high mechanical stability even at high temperatures and can demonstrate excellent performance as a catalyst support for the dry reforming reaction of methane.

[0059] The connection between the above edges may include Si-O-Si covalent bonds.

[0060] The edge-to-edge self-assembly process may involve connecting 2D-SiNS to the edges and cross-linking them by forming highly stable Si-O-Si covalent bonds between adjacent edges. This can play a pivotal role in maintaining stability and withstanding various stress and temperature changes.

[0061] The self-assembly may comprise 50 to 500, more specifically 70 to 400, 100 to 200, or 130 to 175 two-dimensional nanosheets.

[0062] By including two-dimensional nanosheets in the above range, a self-assembly can be formed on a scale suitable for the intended purpose depending on the application.

[0064] Method for manufacturing a self-assembled body

[0065] In another embodiment, a method for manufacturing the self-assembly is provided. It comprises a step of preparing a two-dimensional nanosheet; and a step of encapsulating the two-dimensional nanosheet; and

[0066] The encapsulation step of the above two-dimensional nanosheet may be performed at 21 to 29°C for 5 to 30 hours to encapsulate a plurality of two-dimensional nanosheets.

[0067] At this time, the characteristics of the manufactured self-assembled body are the same as those previously described. Therefore, a detailed description of the self-assembled body will be omitted.

[0069] Specifically, the preparation step of the two-dimensional nanosheet may involve dispersing an aqueous suspension of a two-dimensional nanoreactor in an organic solvent while stirring it within the temperature range for 5 to 60 minutes, and then adding a basic solution.

[0070] A basic solution can be added after 10 to 60 minutes, more specifically 10 to 20 minutes, after dispersion in the above organic solvent.

[0071] The above organic solvent may be cyclohexane.

[0072] The above basic solution may be ammonia.

[0073] The temperature at which the above encapsulation step is performed may be more specifically 21 to 27°C or 22 to 25°C, and the time at which it is performed may be more specifically 7 to 25 hours or 12 to 24 hours.

[0074] By satisfying the above range, it is possible to manufacture a highly organized self-assembled structure, such as a soccer ball, surrounded by a two-dimensional nanosheet monolayer that is self-assembled in an edge-to-edge orientation.

[0075] In particular, when the temperature exceeds the above range, it can be formed as a single-layer planar structure, and when it falls below, it can be formed as a randomly stacked or bowl-shaped structure.

[0076] The encapsulation step of the above two-dimensional nanosheet may be performed in a pH range of 4.0 to 7.0. More specifically, it may be performed in a pH range of 4.0 to 6.0, 4.0 to 5.5, or 4.2 to 5.0.

[0077] As the encapsulation step is performed within the above pH range, the volume charge density of adjacent solutions in a basic solvent system can be much higher around flat surfaces than around edges with very positive curvature of a radius of 12 nm or less. Therefore, this differential potential in the interfacial bilayer near the corner and face surfaces can have the effect of providing a unique possibility for the electrostatic assembly of two-dimensional nanosheets, involving the correct balance of corner-corner van der Waals attraction and face-face electrostatic repulsion, to perform corner-corner connections while avoiding inter-face stacking. More specifically, if the range is below, all surface silanol groups may be protonated, and if it is above, indiscriminate deprotonation of corner and face silanols may occur, creating an even surface charge distribution regardless of distinct regions.

[0079] The method for manufacturing the above self-assembly may further include the step of introducing a solution containing a silica salt prior to the encapsulation step of the two-dimensional nanosheet.

[0080] As described above, a solution containing silica salt can be introduced into the prepared two-dimensional nanosheet at intervals of 5 to 30 minutes. Subsequently, methanol can be added to break down the micelle system. At this time, methanol is introduced to precipitate the generated silica-encapsulated NiCo hydroxide.

[0081] The solution containing the above silica salt may be tetraethyl orthosilicate (TEOS), cyclohexane, Igepal CO-520, NiCo metal hydroxide, ammonia, or a combination thereof.

[0082] The above two-dimensional nanosheet may have one or more selected from the group consisting of dodecyl sulfate, Ni metal, Co metal, and hydroxyl groups inserted therein. In this case, the hydroxyl group refers to a hydroxyl group (-OH) and may refer to a compound containing a hydroxyl group.

[0083] Preferably, one or more selected from the group consisting of dodecyl sulfate, Ni metal, and Co metal may be inserted, and more preferably, dodecyl sulfate may be inserted.

[0084] As described above, the surface charge of the metal hydroxide can be positively charged as it is inserted, and complete peeling can occur when dispersed in a suitable solvent.

[0086] Preferred embodiments and comparative examples of the present invention are described below. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited to the following examples.

[0088] Examples and Comparative Examples

[0089] Example 1

[0090] First, layered NiCo-LDH (NiCo-layered double hydroxide) with inserted dodecyl sulfate (DS) was synthesized and then completely exfoliated into single-layer (SL)-NiCo-LDH. Subsequently, silica encapsulation of the SL-NiCo-LDH was performed. Specifically, the following process was carried out.

[0092] (1) Silica encapsulation of SL-NiCo-LDH (synthesis of 2D-SiNS)

[0093] A reaction solution was prepared by dispersing 200 μL of IGEPAL-CO-520 (poly(oxyethylene)nonylphenyl ether) solution in 6.6 mL of cyclohexane with shaking for 15 minutes at a reaction temperature (Tr) of 23°C. Subsequently, 400 μL of SL-NiCo-LDH suspension (12.5 mg / mL, ca. 250 nm in size and ca. 1 nm in thickness) was added to the reaction solution and shaken again for 15 minutes. After 15 minutes, 33.3 μL of ammonia solution (28.0 vol%) was added to the solution, followed by the addition of 66.6 μL of TEOS (Tetra-ethyl-ortho-silicate) at 15-minute intervals. After maintaining shaking at the above reaction temperature (Tr = 23°C) for 16 hours, methanol was added to the reaction solution to disrupt the micelle system and produce the product. The product was subsequently used in the assembly process.

[0095] (2) Synthesis of SA-SiMS

[0096] 2D-SiNS 23℃ SL-NiCo-LDH encapsulated by a SiO2 shell represented by was precipitated, and the precipitated product was subjected to multiple ethanol washing steps (5 mL, at least 5 times) (@25℃). During these ethanol washing processes, 2D-SiNS 23℃It undergoes a self-assembly process to form SA-SiMS. Afterward, it is dried in an oven at 60°C for more than 12 hours for application to subsequent processes.

[0098] (3) M@SA-SiNS 23℃ Stack composition

[0099] M@SA-SiNS 23℃ The fabrication of the stack was carried out in the same manner as the synthesis of SA-SiMS. After the silica encapsulation reaction, methanol was added to precipitate the product, and the surfactant was removed by heat treatment at 500°C for 5 hours in air, and then converted into metal nanoparticles by heat treatment again at 500°C for 5 hours under reducing conditions. Specifically, the above reducing conditions refer to the conditions of heat treatment at 500°C for 5 hours using 4% H2 / Ar gas in a tubular electric furnace.

[0101] Comparative Example 1

[0102] It was prepared in the same manner as in Example 1, but with the reaction temperature (Tr) set to 15℃ during the silica encapsulation step of SL-NiCo-LDH.

[0104] Comparative Example 2

[0105] It was prepared in the same manner as in Example 1, but with the reaction temperature (Tr) set to 20℃ during the silica encapsulation step of SL-NiCo-LDH.

[0107] Comparative Example 3

[0108] It was prepared in the same manner as in Example 1, but with the reaction temperature (Tr) set to 30℃ during the silica encapsulation step of SL-NiCo-LDH.

[0110] Experimental Example 1: SEM and TEM image analysis of self-assembled bodies and analysis of thickness, lateral dimensions, and zeta potential of 2D-SiNS

[0111] For SA-SiMS prepared as in the examples and comparative examples, emission scanning electron microscope (FE-SEM) images were analyzed.

[0112] FIG. 3 shows a low-field Scanning Electron Microscope (SEM) image of SA-SiMS and an Atomic Force Microscope (AFM) image (bottom left) of a single unit (2D-SiNS) for estimating the thickness of SA-SiMS in a self-assembled structure according to one embodiment.

[0113] FIG. 4 shows a high-field SEM image of SA-SiMS in a self-assembled body according to one embodiment.

[0114] Referring to FIGS. 3 and 4, instead of the generally expected silica-coated NiCo-LDH core@shell or dispersed or randomly stacked nanoparticles according to the embodiment, the presence of SA-SiMS (total size 1.6 ± 0.2 μm), which resembles a highly organized soccer ball surrounded by an unexpectedly edge-to-edge self-assembled 2D-SiNS monolayer, is confirmed through field-emission scanning electron microscope (FE-SEM) images. Additionally, a hollow interior can be observed through randomly generated gaps.

[0115] FIG. 5 shows a low-field TEM image of SA-SiMS and a single unit (2D-SiNS) image (bottom left) for visualizing individual thin 2D-SiNSs in a self-assembled structure according to one embodiment.

[0116] In Figure 5, the transmission electron microscope (TEM) image visualized thin, wrinkled walls in the form of droplets of SA-SiMS composed of edge-to-edge sharing of each thin 2D-SiNS23°C.

[0117] FIG. 6 is a HAADF-STEM image superimposed with an EDX line profiling of SA-SiMS showing the coexistence of Si, Ni, and Co elements with a hollow interior in a self-assembled structure according to one embodiment.

[0118] FIG. 18 shows an XRD graph of a self-assembled body according to one embodiment.

[0119] In summary, as measured by AFM in Fig. 3, the thickness is confirmed to be approximately 11.9 nm. Additionally, referring to Fig. 5, the HAADF-STEM image of the SA-SiMS reveals a hollow interior with an internal space of 1.6 μm. Meanwhile, through energy-dispersive X-ray spectroscopy (EDX)-based elemental mapping and line profiling shown in Fig. 6, it was found that Si, Ni, and Co elements coexist at the SA-SiMS boundary, indicating that LDH is well encapsulated within the silica thin film.

[0120] In addition, through X-ray diffraction (XRD) analysis of Fig. 18, it can be confirmed that the original in-plane crystal structure of NiCo-LDH is maintained within the ultrathin amorphous silica layer.

[0121] Surprisingly, the soccer ball-like structure of SA-SiMS was well maintained even after drying, which is an exceptional phenomenon for such ultrafine hollow structures with ultrathin walls at the nanoscale.

[0123] FIG. 7 shows SEM images and AFM images (top row) (i) and TEM images (bottom row) (ii) of 2D-SiNS for thickness estimation in a self-assembled body according to Comparative Example 1.

[0124] FIG. 8 shows an SEM image and an AFM image (top row) (i) and a TEM image (bottom row) (ii) of 2D-SiNS for thickness estimation in a self-assembled body according to an embodiment.

[0125] FIG. 9 shows SEM images and AFM images (top row) (i) and TEM images (bottom row) (ii) of 2D-SiNS for thickness estimation in a self-assembled body according to Comparative Example 3.

[0126] Referring to Figures 7 through 9, it can be seen that the silica encapsulation reaction temperature (Tr) has a significant effect on the edge-to-edge self-assembly process, which exhibits various modes of interaction between sheets.

[0127] 2D-SiNS15°C fabricated at a slightly lower temperature (Tr = 15°C) was randomly stacked without exhibiting a distinct preference for edge-to-edge interactions (indicated as SA-Si15°CStack), while 2D-SiNS20°C formed at a slightly higher temperature of 20°C (Tr = 20°C) began sharing edges and formed a bowl-shaped self-assembled structure with curvature (indicated as SA-SiBowl). Crucially, the formation of a soccer ball-like SA-SiMS was observed only through 2D-SiNS23°C prepared at Tr = 23°C. When the temperature was increased further (Tr = 30°C), the edge-to-edge oriented self-assembled 2D-SiNS30°C exhibited a 2D monolayer planar structure without distinct stacking or curvature (indicated as SA-Si30°C Sheet).

[0129] To better understand the critical effect of Tr fluctuations within a narrow range on the formation of different self-assemblies, the thickness, lateral size, and zeta potential of 2D-SiNS synthesized at different temperatures were analyzed.

[0130] Through this, it was confirmed that temperature conditions during the hydrolysis and condensation reactions of TEOS affect the silica layer formation rate, which can lead to changes in thickness and composition, and that this can have a significant impact on physical and chemical properties. More specific details are described below.

[0131] FIG. 10 shows a graph of the thickness and side dimensions of a 2D-SiNS building unit according to the reaction temperature in a self-assembled structure according to one embodiment and a comparative example.

[0132] Referring to FIGS. 3, FIGS. 7 to 9, and FIG. 10, AFM analysis reveals that the 2D-SiNS in the self-assembly according to Comparative Example 1 has a thickness of 7.6 nm, the 2D-SiNS in the self-assembly according to Comparative Example 2 has a thickness of 9.3 nm, the 2D-SiNS in the self-assembly according to Comparative Example 3 has a thickness of 16.1 nm, and the 2D-SiNS in the self-assembly according to the Example has a thickness of 11.9 nm. In other words, while the thickness of the 2D-SiNS increases with increasing Tr, the lateral size of the sheet (measured by TEM) remains almost unchanged.

[0133] Figure 11 shows a graph of surface charge measurements of 2D-SiNS synthesized in water at various temperatures.

[0134] As a result of measuring the zeta potential of 2D-SiNS synthesized at various Trs after washing with water, the thinner silica layer of 2D-SiNS at 15°C, where 2D-SiNS is well dispersed and many corners are exposed, showed a zeta potential closer to that of uncoated NiCo-LDH, while the thicker shell (synthesized at high Trs) gradually obtained more negative potential values ​​due to the increased contribution of deprotonated silanol to the silica shell surface.

[0135] However, in the case of 2D-SiNS at 23°C and 2D-SiNS at 30°C, the thick overgrown silica layer had a very large effect on the surface charge (the zeta potential was lowered to a maximum of -37.1 mV), and the NiCo-LDH core covered by the silica shell made no significant contribution, so the zeta potential did not change further even as the temperature increased. The observed zeta potential trend had a significant impact on the control of the 2D-SiNS self-assembly behavior, creating diverse and complex structures.

[0136] In the case of 2D-SiNS15℃, the formation of inter-plane stacked aggregates is due to the insufficient electrostatic repulsion force to push wide flat surfaces together caused by the imperfect thin silica shell, and instead, the van der Waals (vdW) attraction between planes becomes dominant, causing them to stack.

[0137] Thick silica layers grown at high Tr generated stronger electrostatic repulsion between more negatively charged surfaces, preventing broad planar stacking while simultaneously inducing edge-to-edge interactions due to dominant vdW attraction along the edges, thereby creating self-assembly of bowl-shaped SA-SiBowl and spherical SA-SiMS such as soccer balls composed of 2D-SiNS20°C and 2D-SiNS23°C nanosheets.

[0138] On the other hand, the excessive growth of the silica shell thickness in 2D-SiNS30℃ provided strong bending stiffness to the nanosheets and allowed for the formation of a wide and infinite self-assembly of 2D planar nanosheets that were maintained with shared edges in the SA-Si30℃ sheet.

[0140] Experimental Example 2: Analysis of the Mechanism of Morphological Evolution of Self-Assemblies

[0141] To further investigate the interesting assembly process of SA-SiMS from 2D-SiNS23℃, morphological evolution analysis of the early stages was performed on the self-assembled body according to the example using TEM and SEM.

[0142] FIG. 12 shows images investigating the mechanism of morphological evolution of SA-SiMS in a self-assembled body according to one embodiment. Specifically, (a) a diagram of micelle destruction after the addition of MeOH (top row) (i), a TEM image after silica encapsulation (middle row), an image where adjacent sheets are barely visible after the addition of ethanol (ii), and (b) a diagram showing various morphological evolutions of SA-SiMS in ethanol (top row) (i), TEM (middle row), and SEM images (bottom row) (ii).

[0143] TEM images after ending the silica encapsulation reaction time at 23°C and adding methanol to break up the micelles confirm that there is no self-assembled structure (a). However, in TEM images of the solid recovered after sequential washing with ethanol, nanosheets adjacent to the sides begin to appear little by little.

[0144] After washing five times with ethanol, curved concave microstructures begin to appear due to edge-to-edge assembly of monolayer 2D-SiNS23℃ and gradually evolve into closed hollow microstructures composed of 2D-SiNS monolayer walls (b).

[0146] Experimental Example 3: Analysis of Surface Charge Characteristics and Mechanical Strength of 2D-SiNS

[0147] The size of SA-SiMS measured by TEM (1.6 ± 0.2 μm) was in good agreement with the size (1.5 μm) obtained from dynamic light scattering (DLS) analysis. For reference, dynamic light scattering analysis was performed using SA-SiMS dispersed in ethanol.

[0148] Furthermore, the thermogravimetric analysis (TGA) of SA-SiMS, to be discussed later, did not show significant mass loss due to the decomposition of organic components, which provided evidence for the absence of organic surfactants in the self-assembled structure.

[0149] These results suggest that micelle surfactants are effectively removed during methanol / ethanol washing and play no role in the self-assembly mechanism. Essentially, self-assembly occurs due to the inherent surface properties of 2D-SiNS23°C, which possess optimal surface charge and mechanical properties.

[0150] Accordingly, it can be assumed that anisotropic 2D-SiNS facilitates an abnormal self-assembly process because they have different curvature-dependent domains with distinct surface characteristics that maximize inter-plane repulsion and allow attraction between edges.

[0151] To verify this, a titration experiment was performed.

[0152] Figure 13 shows a graph of titration performed on 2D-SiNS.

[0153] Referring to Fig. 13, the titration curve of the 2D-SiNS aqueous solution at 23°C is characterized by two distinct equilibrium points (Eq1 = 8.0 pH, Eq2 = 5.4 pH), whereas the spherical SiO2NP (50 nm) shows only one equilibrium point (Eq1 = 5.1). Unlike the 0D spherical SiO2NP, the 2D-SiNS has two distinct regions: an edge with a positive radius of curvature of a few nm and a plane with a radius of curvature of almost zero.

[0154] To support this, the selective interaction of (+)-AuNP (5.0 nm) with 2D-SiNS23℃ at various pH was further investigated.

[0155] Figure 14 shows TEM images illustrating the assembly between 2D-SiNS and oppositely charged [(+)-AuNP] spherical nanoparticles at various pH values ​​in 2D-SiNS.

[0156] Referring to Fig. 14, at pH 3.78, all surface silanol groups were protonated and no interactions were observed. When the pH was increased above 7.45, (+)-AuNPs interacted indiscriminately on the entire surface at the edges and faces, indicating the indiscriminate deprotonation of edge and face silanols, which creates a uniform surface charge distribution regardless of distinct regions. In other words, under sufficiently high pH conditions or in solvent systems more basic than water (e.g., ethanol), the volume charge density of adjacent solutions will be much higher around flat faces than around edges with very positive curvature of ~12 nm radius.

[0157] Therefore, these differentiated potentials in the interfacial bilayer near the edge and face surfaces provide a unique possibility for the electrostatic assembly of 2D-SiNS, which involves the correct balance of edge-to-edge van der Waals attraction and face-to-face electrostatic repulsion, to perform edge-to-edge connection while avoiding inter-face stacking.

[0158] Nevertheless, the aforementioned synthesis temperature-dependent self-assembly process confirmed that SA-SiMS cannot be constructed using surface charge alone. In other words, it may be necessary to satisfy both temperature and pH conditions. To achieve a self-assembled structure like a soccer ball, it is essential to consider the flexibility of 2D-SiNS, as each nanosheet must be bent to achieve the required micron-scale curvature.

[0159] To gain insight into the physical bending behavior of 2D-SiNS, an AFM-based stiffness measurement study was performed on a single 2D-SiNS suspended over a small hole.

[0160] Figure 15 shows a separation and deformation test graph measured at the center of the suspended portion of 2D-SiNS for each 2D-SiNS of different thicknesses synthesized at 23°C and 30°C.

[0161] Referring to Fig. 15, the AFM tip force versus separation graph shows a steeper slope for the thick 2D-SiNS 30°C (~16.1 nm thickness), indicating greater stiffness compared to the thin 2D-SiNS 23°C (~11.9 nm thickness). For reference, the average Young's modulus of the 2D-SiNS 23°C and 2D-SiNS 30°C was found to be 366.7 MPa and 872.3 MPa, respectively.

[0162] To provide a more visual representation, force versus strain curves were generated using pinpoint nanomechanical mode analysis. 2D-SiNS23℃ showed distinct bending at relatively low applied forces, whereas the curve for 2D-SiNS30℃ appeared as a straight line, indicating the high sensitivity of 2D-SiNS23℃ to force-induced deformation.

[0163] In addition, in an attempt to completely rupture 2D-SiNS, 2D-SiNS 30°C (36 nN) required a greater force than 2D-SiNS 23°C (8 nN).

[0164] In addition, as expected, we attempted to induce self-assembly using relatively hard and thick 7 nm NiCo-LDH silica encapsulation under the same conditions at 23 ℃, but no assembly was observed.

[0165] In addition, during attempts to vary the silica layer thickness by changing the concentration of TEOS while silica encapsulating NiCo-LDH at 23°C, it was observed that stack or bowl-shaped structures of different sizes were formed. Specifically, when the concentration of TEOS was 1 wt% or more or 0.8 wt% or less, hollow spherical self-assemblies were not formed. In other words, it can be seen that it is appropriate to add a solution containing silica salt in a concentration range of 0.8 wt% to 1 wt%.

[0166] In addition, reducing or removing other reaction components (surfactants and ammonia) had an adverse effect on the SA-SiMS yield.

[0167] While using ethanol as a washing solvent was important for providing a very uniform SA-SiMS yield, other solvents such as water, acetone, dimethylformamide, and acetonitrile did not effectively promote the desired edge-to-edge assembly process.

[0168] These results show that not only the optimized surface electric double layer (EDL) charge density but also the physical flexibility of 2D-SiNS is important.

[0169] Based on the detailed results above, a key mechanistic perspective for converting to SA-SiMS through a corner-to-corner self-assembly process of 2D-SiNS23℃ can be proposed as shown in Fig. 1.

[0170] Figure 1 shows a schematic diagram of the process of interlocking and self-assembling 2D-SiNS in an edge-to-edge orientation with a hollow micron-sized shell (SA-SiMS) such as a soccer ball.

[0171] When placed in ethanol, 2D-SiNS23°C undergoes deprotonation of surface silanol groups, generating distinct EDLs near the negatively charged surface and edge surfaces. Thicker EDLs, formed with higher volume charge densities near the surface, lead to strong electrostatic repulsion, which outweighs face-to-face van der Waals attraction. However, the electrostatic repulsion between edge surfaces, where relatively thin EDLs are formed, is not strong enough to overcome van der Waals attraction. Consequently, edge-to-edge interactions prevail, and the nanosheets begin to move sideways through van der Waals interactions. Furthermore, the thin and flexible 2D-SiNS23°C nanosheets bend to achieve the micron-scale curvature required to surround hollow spherical shells within the edge-to-edge connections, exhibiting thermodynamically favored self-assembly that benefits from both enthalpic and entropic effects. Consequently, it becomes possible to finally fabricate self-assembled bodies such as those in the embodiments of the present invention.

[0173] Experimental Example 4: Structural Stability Evaluation

[0174] The self-assembled body (SA-SiMS) according to the example was treated in various solvents to test its structural stability in various aqueous and organic solutions.

[0175] FIG. 16 shows an SEM image of SA-SiMS showing the reversible shrinkage of the entire structure in a water / ethanol system in a self-assembled structure according to one embodiment.

[0176] Referring to Fig. 16, replacing ethanol (the solvent optimized for assembly) with water preserved the edge-edge (EE)-links but led to characteristic shrinkage of the overall structure. The shrunken structure could be restored to its original form by reintroducing ethanol as the solvent. Surprisingly, SA-SiMS demonstrated exceptionally high structural stability even under high-temperature conditions after drying.

[0177] When SA-SiMS powder was heat-treated at 500°C in an air or H2 / Ar atmosphere, there was no significant change in the overall hollow structure. While the overall hollow structure was preserved, heat treatment in air converted the core NiCo-LDH into a thin porous metal oxide layer (MO@SA-SiMS) inside the bilayer silica, whereas heat treatment in H2 / Ar formed metal NCs (2.0 ± 0.4 nm) (M@SA-SiMS) trapped inside the bilayer silica. This was also confirmed by HAADF-STEM, HRTEM, EDX-based elemental line profiling, XRD, and BET surface area and pore size measurements (Figs. 17 to 20).

[0178] The exceptional structural stability of SA-SiMS distinguishes it from conventional self-assembly, which relies on somewhat weak or reversible interactions such as electrostatic forces, hydrogen bonding, vdW forces, or weak metal-ligand coordination, even at high temperatures and under various solvent and dry conditions. The edge-to-edge self-assembly process involves connecting 2D-SiNS at the edges and cross-linking them by forming highly stable Si-O-Si covalent bonds between adjacent edges, which can play a pivotal role in maintaining stability and withstanding various stress and temperature changes.

[0180] Experimental Example 5: Evaluation of Catalytic Activity and Measurement of Active Metal Surface Area of ​​Catalyst

[0181] First, the catalytic activity of the metal nanoparticle catalyst prepared as in the examples and comparative examples, namely M@SA-SiMS (M = NiCo), was evaluated through dry reforming of methane (DRM).

[0182] First, different 2D double-layer silica closed NiCo-NCs (ca. 2 nm), namely SA-Si 15°C Stack prepared by reducing heat treatment (500°C, H2 / Ar), stacked SiNS (SiNS 23°C Stack), and SA-Si 30°C Sheet prepared at 23°C, were prepared. It was confirmed through XRD and ICP that the chemical composition of these synthesized catalysts was nearly similar to M@SA-SiMS.

[0183] Dry methane reforming was carried out in a continuous fluidized fixed-bed reactor at atmospheric pressure. 40 mg of catalyst was diluted with 0.5 g of quartz sand using a 40-60 mesh sieve and fed into a 10 mm inner diameter quartz tube serving as the reactor. Pure H2 (50 mL min) was heated at 800°C for 1 hour. -1 After reducing the catalyst with ), the reactor was cooled to 700°C. 22,500 mL g of a gas mixture with a CH4:CO2:N2 ratio of 1 atm:1 atm:1 atm cat -1 h -1 It was injected into the reactor for 20 hours at a weight hour space velocity (WHSV). For catalysts with high activity and reaction stability, additional DRM was performed at 700°C for 100 hours.

[0184] Gas products were analyzed using a YL6500 online GC (Young-In Chromass) equipped with a thermal conductivity detector (Carboxen 1000 column) to detect H2, CH4, CO2, and CO, and N2 was used as an internal standard. CH4(X CH4 ) and CO2(X CO2The conversion and H2 / CO ratio were calculated using the following equation.

[0185]

[0186] F CO2 in , F CO2 out , F CH4 in , F CH4 out , F H2 out , and F CO2 out represents the internal and external volumetric flow rates of CO2, CH4, H2, and CO, respectively.

[0188] In addition, the active metal surface area of ​​the metal nanoparticle catalysts prepared as in the examples and comparative examples was measured.

[0189] H2-pulse chemisorption was performed to determine the active metal surface area of ​​each catalyst, and the catalyst (100 mg) was heated at 800°C for 1 hour with a 10% H2 / Ar flow (30 mL min -1 After in situ reduction under ), Ar flow (30 mL min -1 It was cooled under ) after the temperature stabilized, until the area of ​​the continuous H2 peak stabilized, at a 5% H2 / Ar flow (30 mL min). -1 A pulse of ) was injected. The metal surface area was calculated from the volume of adsorbed H2, assuming the adsorption stoichiometry to be 1.

[0191] FIG. 17 shows a differential volume graph with respect to pore size and a volume graph with respect to relative pressure for deriving the BET surface area of ​​SA-SiMS in a self-assembled body according to one embodiment.

[0192] FIG. 19 shows TEM and HAADF-STEM images of SA-SiMS after heat treatment at 500°C in an air atmosphere for a self-assembled body according to one embodiment.

[0193] FIG. 20 shows TEM and HAADF-STEM images of SA-SiMS and EDX-based elemental line profiling after heat treatment at 500°C in an H2 / Ar atmosphere for a self-assembled body according to one embodiment.

[0194] Figure 21 is an image showing the DRM performance and morphological analysis of the catalyst after use through M@SA-SiMS.

[0195] Specifically, in Fig. 21 (a), WHSV = 22 500 mL gcat -1 h- 1 CH4(i) and CO2(ii) conversion in DRM for various assembly structures including M@SA-SiMS and NiCo NC as catalysts for 20 hours at 700°C, long-term DRM test in M@SA-SiMS for 100 hours (graphs inserted in (i) and (ii)), H2 / CO ratio for M@SA-SiMS and other assembly structures (iii), and H2 / CO ratio for M@SA-SiMS for 100 hours DRM reaction (graph inserted in (iii)).

[0196] Also, in Fig. 21 (b), TEM images and high-magnetic TEM images (inset) of M@SA-SiMS (i), M@SA-Si15℃Stack (ii), M@SiNS23℃Stack (iii) and M@SA-Si30℃Sheet (iv) before pretreatment (fresh) (left row), after pretreatment (middle row), and after 20 hours of DRM (right row) are shown.

[0197] In addition, Figure 21 (c) shows a graph comparing the metal surface area of ​​all catalysts after pretreatment and the metal surface area calculated by H2-Pulse measurement for DRM for 20 hours (i). It also shows a graph comparing the Ni-NC sizes of all catalysts before, after pretreatment, and after DRM (ii), TGA profiles of various catalysts after DRM for 20 hours at 700°C (iii), and enlarged TGA profiles (inset in (iii)).

[0199] Referring to Fig. 21(a), it can be seen that M@SA-SiMS, which has a hollow soccer ball-like shell structure, exhibits the highest initial CH4 and CO2 conversion rates with H2 / CO = 0.8. In addition, high activity was maintained for up to 100 hours at 700 °C (final CH4 and CO2 conversion rates of 70.3% and 74.5%, respectively, with H2 / CO = 0.8).

[0200] The consistently high H2 / CO ratio for M@SA-SiMS suggests smooth adsorption and activation of CH4 and CO2 throughout the entire DRM reaction period. High-magnification TEM images of catalysts pretreated at 800 °C under H2 showed a slight increase in NiCo NC size (max. ca. 5 nm) due to thermal sintering, and the NiCo NCs of all pretreated samples exhibited a consistent XRD pattern corresponding to fcc NiCo NCs, which was also confirmed to remain uniformly dispersed and well protected within the 2D-SiO2 bilayer shell.

[0201] In addition, ICP-AES analysis showed that the Ni / Co ratio of the pre-treated catalyst remained almost unchanged compared to the initial Ni / Co ratio (Ca. 6 wt% Ni and 1.5 wt% Co). However, low-magnification TEM images of the pre-treated M@SA-Si30 ℃Sheet and M@2D-SiNS23 ℃Stack showed the formation of a collapsed and aggregated bulk silica morphology consisting of randomly stacked and mutually fused 2D-SiO2 sheets.

[0202] Significant changes in the macroscopic form of these catalysts are thought to have occurred through interfacial condensation reactions of high-density silanols exposed to flat surfaces, which are further facilitated by the interface stacking of the flat surfaces. This irreversible aggregation results in much denser bulk-sized silica structures that significantly restrict molecular access to embedded metal active sites and cause catalyst deactivation.

[0203] In contrast, the pre-treated M@SA-SiMS and M@SA-Si15°CStack retained their original high-exposure surface characteristics, consisting of several layers and a very thin shell, respectively. The morphological preservation of M@SA-Si15°CStack under pre-treatment conditions may be due to the smaller number of surface silanol functional groups present in the thinner, partially formed silica layer under 15°C sol-gel conditions; consequently, inter-sheet fusion does not occur well, and it exhibits initial catalytic activity equivalent to M@SA-SiMS. The unusually high structural resilience and consistent catalytic activity of M@SA-SiMS are attributed to the minimum interfacial silica surface area among the edge-to-edge assembled 2D-SiNS, which significantly limits face-to-face fusion between adjacent silica sheets during reductive pre-treatment and also contributes to sustained catalytic performance.

[0204] As a result of verification, in the H2-pulse chemisorption study using the pretreated catalyst, M@SA-SiMS and M@SA-Si15℃Sack had active metal surface areas of 1.63 and 1.21 m², respectively. 2 / g cat It was measured as, and the amount of absorbed hydrogen was also 0.93 and 0.69 cm 3 H2·g cat -1 It was measured as.

[0205] This means that the internally open hollow shell structure allows the maximum exposure of the accessible surface area compared to M@SA-Si30℃Sheet and M@2D-SiNS23℃Stack (Fig. 21 a(i)).

[0206] In particular, TEM images of M@SA-SiMS after the DRM reaction showed that the morphology of the hollow micron structure was maintained without significant aggregation or collapse (Fig. 21 b(i)). The resilient catalytic activity of M@SA-SiMS was attributed to its excellent mechanical stability even in a high-temperature reaction gas environment.

[0207] The intact, hollow, high-surface-area structure of the catalyst facilitated the necessary molecular transport and high-temperature gas convection around the enclosed and well-protected metal sites within the bilayer silica, significantly enhancing the sustained probability of the temperature-sensitive DRM reaction. In contrast, referring to Figures 21 b(ii) and b(iii), the M@SA-Si 15°C Stack and M@SiNS 23°C Stack exhibited severe silica structural deformation, showing low DRM performance despite similar chemical compositions of the catalysts. Furthermore, the thermogravimetric analysis (TGA) graph for M@SA-SiNS (Figure 21 c(iii)) showed no weight loss, indicating the absence of carbon deposition.

[0208] Meanwhile, a slight weight increase was observed in the temperature range of 200–400 °C (refer to the inset graph in Fig. 21 c(iii)) due to metal oxidation, which represents the amount of exposed active metal surface area. In particular, the thin SiO2 shell of M@SA-SiMS effectively stabilized the small-sized (~5 nm) NiCo-NCs, which are resistant to coke formation, by preventing the escape of the catalyst to the unbound outer surface and subsequent sintering after the DRM reaction (refer to the inset image in Fig. 21 b(i)).

[0209] On the other hand, in the case of M@SA-Si15℃Stack, M@2D-Si30℃Sheet, and M@SiNS23℃Stack, the absence of carbon deposition on the catalyst surface can be interpreted as a result of the lack of activity in the DRM process.

[0210] In particular, M@SA-SiMS exhibited the highest catalytic activity and stability by continuously maintaining carbon balance throughout the DRM reaction. The sustained high DRM activity of M@SA-SiMS is attributed to its robust hollow support structure and stabilized small catalyst size; furthermore, measurements of the active metal surface area and hydrogen adsorption capacity of the M@SA-SiMS catalyst after use revealed a high active metal surface area (1.52 m²). 2 / gcat ) and large hydrogen adsorption capacity (0.87 cm 3 H2·g cat -1 It was proven that by maintaining ) the M@SA-Si15℃Stack, M@SA-Si30℃Sheet, and M@2D-SiNS23℃Stack catalysts exhibited significantly reduced values, while showing excellent performance (Fig. 21 c(i)).

[0212] That is, the self-assembly according to an embodiment of the present invention can provide a corner-to-corner self-assembly process in which 2D-SiNS evolve into SA-SiMS, which are hollow micron-sized shells, and a self-assembly manufactured through the same.

[0213] This method enables precise and controlled assembly by leveraging electrostatic forces dependent on nanometer-scale extreme anisotropic surface curvature and the mechanical flexibility of 2D-SiNS, overcoming the typically expected inter-plane stacking. The self-assembled structure resulting from this study demonstrates excellent mechanical stability, maintaining its structure even under extreme conditions including high temperatures and various solvents.

[0214] As previously mentioned, remarkable activity was confirmed as a result of the DRM reaction of SA-SiMS, and such characteristics can be highly promising in applications requiring durability, such as catalysts. NiCo-NCs demonstrated excellent thermal durability and activity due to their very small size and limited mobility within the thin double-layer nanospace. Going beyond catalytic activity, it was confirmed that stable and functional materials can be designed using nanoscale self-assemblies.

[0216] The present invention is not limited to the above embodiments and can be manufactured in various different forms, and those skilled in the art will understand that the invention can be implemented in other specific forms without changing the technical concept or essential features of the invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

Claim 1 A self-assembly in which two-dimensional nanosheets are joined edge to edge to form a hollow spherical shape. Claim 2 A self-assembly according to claim 1, wherein the two-dimensional nanosheet comprises an electric double layer in the edge and face regions. Claim 3 A self-assembly according to claim 1, comprising a silica coating layer on the surface of the two-dimensional nanosheet. Claim 4 A self-assembly, wherein the silica coating layer comprises a crystal structure of a metal-electric double layer, in paragraph 3. Claim 5 In paragraph 4, the crystal structure of the metal electric double layer is a self-assembly in which a metal hydroxide containing NiCo is encapsulated inside a silica coating layer. Claim 6 A self-assembled body according to claim 1, wherein the thickness of the two-dimensional nanosheet is 10.0 to 15.0 nm. Claim 7 In paragraph 3, the self-assembly, wherein the thickness of the silica coating layer is 5 to 20 nm. Claim 8 A self-assembly according to claim 1, wherein the inner diameter of the self-assembly is 0.5 to 5.0 μm. Claim 9 In claim 1, the surface area of ​​the self-assembly is 1 μm 2 to 10 μm 2 Person, self-assembly. Claim 10 A self-assembly according to claim 1, wherein the connection between the corners includes a Si-O-Si covalent bond. Claim 11 The self-assembly of claim 1, wherein the self-assembly comprises 50 to 500 two-dimensional nanosheets. Claim 12 A method for manufacturing a self-assembly, comprising: a step of preparing a two-dimensional nanosheet; and a step of encapsulating the two-dimensional nanosheet; wherein the encapsulation step of the two-dimensional nanosheet is performed at 21 to 29°C for 5 to 30 hours to encapsulate a plurality of two-dimensional nanosheets. Claim 13 In claim 12, the method for manufacturing the self-assembly further comprises the step of introducing a solution containing a silica salt prior to the encapsulation step of the two-dimensional nanosheet. Claim 14 A method for manufacturing a self-assembly according to claim 12, wherein the two-dimensional nanosheet has one or more types selected from the group consisting of dodecyl sulfate, Ni metal, Co metal, and hydroxyl groups inserted therein. Claim 15 A method for manufacturing a self-assembly, wherein, in claim 12, the encapsulation step of the two-dimensional nanosheet is performed in the pH range of 4.0 to 7.0.

Images