KR101272318B1 - The method for preparing core/shell nano-structures of shell with Titanium dioxide or Gold-Titanium dioxide and the nano-structures prepared thereby - Google Patents

Abstract

The hybrid nanostructure having a nuclear / shell structure having a titanium dioxide shell or a nuclear / shell structure having a gold-titanium dioxide shell using a direct coating process of the beads prepared according to the present invention is a diblock copolymer or As the prepared sol-gel precursor solution is used as it is, not only the manufacturing process is simple, but also a structure having a mesoporous structure only by controlling the relative ratio thereof when the block copolymer and the titanium dioxide sol-gel precursor solution are mixed. Can be derived easily. In addition, the composite nanostructure including titanium dioxide and its active ingredient and gold nanoparticles that reacts sensitively to light exhibits higher photocatalytic activity due to the synergistic effect of the combination of the materials, thereby decomposing environmentally friendly devices and contaminants. It can be usefully applied to various fields such as.

Description

Method for preparing core / shell nano-structures of shell with Titanium dioxide or Gold-Titanium dioxide and the nano-structures prepared thereby}

The present invention relates to a method for producing a nanostructure having a core / shell structure having titanium dioxide or gold-titanium dioxide as a shell, and a nanostructure manufactured thereby.

Titanium dioxide has three crystal structures such as rutile, anatase, and brookite. Among them, rutile has good refractive index, hardness, and dielectric constant, mainly for industrial, paint, white pigment, cosmetics, and food additives. Anatase has excellent stability at low temperatures and is widely used as a photocatalyst, and brookite is found only in natural minerals. Titanium dioxide is harmless to human body and is widely used in paint, printing ink, plastic, paper, synthetic fiber, rubber, capacitor, crayon, electric and electronic device.

Titanium dioxide is also one of the representative semiconductor materials used as photocatalysts. In general, a photocatalyst refers to a catalyst that plays a role of decomposing surrounding pollutants by oxidizing and reducing a reaction by receiving light energy, that is, a catalyst that increases the photoreaction rate using light. Titanium dioxide is frequently used because it is relatively inexpensive compared to other materials, has excellent durability and abrasion resistance as a photocatalyst, and is a non-toxic material having excellent stability.

On the other hand, semiconductors such as titanium dioxide have an energy band structure. The highest energy band occupied by the electrons in the energy band of the semiconductor is called the valence band, and the lowest energy band not occupied by the electrons is called the conduction band. Their energy difference is called band gap energy, which has a unique value for each material. When irradiated with light of energy greater than the band gap energy inherent in such semiconductor materials, electrons are excited in the valence band and are transferred to the conduction band, and holes are formed in the valence band, and these electron-hole pairs Harmful oxidative and reduction reactions caused by the decompose harmful substances around.

The energy band spacing in the semiconductor material prevents the rapid recombination of electrons and holes induced in the valence band and conduction band, thereby extending the duration of the photochemical oxidation / reduction reaction. However, semiconductors having a large band gap (3.2 eV), such as titanium dioxide, have a property of absorbing only light having a short wavelength corresponding to a range of less than 400 nm, and thus have a disadvantage in that they cannot absorb visible light, which occupies most of solar energy.

In order to make up for such drawbacks, studies have recently been actively conducted to hybridize materials of different components to titanium dioxide. In particular, the surface spacing of these components is due to the introduction of a semiconductor material that can excite electrons by absorbing light in the visible range, such as silica, with a relatively small band gap (1.12 eV) or by hybridizing precious metal nanoparticles such as gold and silver. Due to the inducing effect of the plasmon properties, there is a recent increase in the interest in expressing the improved properties that do not have a single component of titanium dioxide.

Methods of manufacturing such composite nanostructures include ion implantation, sputtering, and photoreduction reaction methods, which are not advantageous in terms of economics because most of them require expensive equipment or adopt complex multi-step processes. In addition, when manufacturing the multi-component particles have a disadvantage in that the uniformity of the components in the particles, and difficult to control in the form of the particles.

On the other hand, the sol-gel process, which is a liquid phase method, is capable of mixing and preparing raw materials at the molecular level, thereby increasing uniformity of the prepared particles, producing particles having a large surface area, and lowering the sintering temperature. It has been widely used in the preparation of multicomponent composites. In particular, the sol-gel process using a high-purity alkoxide hydrolysis has a wide application range, there is an advantage that the final product can be variously controlled in the form of powder, monolith or fiber.

Therefore, the present inventors have prepared a method for producing a nanostructure having a core / shell structure having a titanium dioxide or a gold-titanium dioxide using a self-assembled biblock copolymer and a sol-gel process, and a composite structure manufactured thereby. To study the present invention was completed.

An object of the present invention is to provide a method for producing a nanostructure of the nucleus / shell structure having a titanium dioxide or gold-titanium dioxide as a shell.

Another object of the present invention is to provide a nucleus / shell structure nanostructure having titanium dioxide or gold-titanium dioxide as a shell.

In order to achieve the above object, the present invention provides a method for producing a nanostructure of the nucleus / shell structure having a shell of titanium dioxide or gold-titanium dioxide using a self-assembled diblock copolymer and a sol-gel process.

In addition, the present invention provides a nanostructure having a nuclear / shell structure having titanium dioxide or gold-titanium dioxide manufactured by the method as a shell.

According to the present invention, a method for producing a nanostructure having a shell of titanium dioxide or gold-titanium dioxide as a shell is not only a simple manufacturing process but also has a higher photocatalytic activity due to the combination of gold and titanium dioxide. It can be usefully applied to various fields such as device and contaminant decomposition.

1 is a conceptual diagram showing a manufacturing step of the present invention;
2 is a surface SEM photograph of a nanostructure having a nucleus / shell structure according to the present invention;
3 is an absorbance spectrum of an ultraviolet-visible spectrophotometer for the optical properties of a nanostructure having a nucleus / shell structure according to the present invention;
Figure 4 is a graph showing the photocatalytic activity of the nanostructure having a nuclear / shell structure according to the present invention.

Hereinafter, the present invention will be described in detail.

The present invention

Dissolving the amphiphilic diblock copolymer to prepare a reverse micelle solution (step 1);

Dissolving the titanium dioxide precursor in ethanol or isopropanol solvent and adding hydrochloric acid or acetic acid to prepare a sol-gel precursor solution (step 2);

Preparing a titanium dioxide-diblock copolymer nanostructure by mixing the reverse micelle solution prepared in step 1 and the sol-gel precursor solution prepared in step 2 (step 3);

Coating the titanium dioxide-diblock copolymer nanostructures prepared in step 3 on the beads (step 4);

Cleaning and drying the beads coated in step 4 (step 5); And

Nano-nuclear shell structure having titanium dioxide as a shell comprising the step of removing the diblock copolymer by heating the beads coated with the titanium dioxide-diblock copolymer coated in step 5 by high temperature heat treatment (step 6). It provides a method for producing a structure.

First, step 1 is a step of preparing a reverse micelle solution by dissolving an amphiphilic diblock copolymer using 1,4-dioxane as a solvent. Reverse micelles mean that when the surfactant is dissolved in an organic solvent, the surface of the hydrophilic portion forms a nucleus and the lipophilic portion contacts the organic solvent, as opposed to water. It is preferable to introduce | transduce poly (styrene-block-ethylene oxide) in 0.1-1 weight% as an amphiphilic copolymer into a 1, 4- dioxane solvent, and it is more preferable that it is 0.5 weight%. If the content is less than 0.1% by weight, there is a problem that the titanium dioxide nanoparticles are not arranged, if it exceeds 1% by weight it is difficult to form a single molecule micelle arrangement in the process of forming a thin film by coating.

Step 2 is a step of dissolving the titanium dioxide precursor in ethanol or isopropanol solvent and adding hydrochloric acid or acetic acid to prepare a sol-gel precursor solution. Titanium tetra-isopropoxide (TTIP), titanium tetrabutoxide, titanium alkoxide, etc. may be used as a titanium dioxide precursor, and ethanol, isopropanol, etc. may be used as a solvent. The solvent may be used to prepare the titanium precursor solution, but is not limited thereto. It is more preferable to use concentrated hydrochloric acid as an acid, titanium tetraisopropoxide as a titanium dioxide precursor, and isopropanol as a solvent.

The acid opens or recesses the polyethylene oxide block portion of the copolymer of step 1, and simultaneously hydrolyzes the titanium dioxide precursor so that dense titanium dioxide nanoparticles can be formed in the open or recessed polyethylene oxide portion.

Step 3 is a step of preparing a titanium dioxide-diblock copolymer nanostructure by mixing the reverse micelle solution prepared in step 1 and the sol-gel precursor solution prepared in step 2. The ratio of reverse micelle solution and titanium dioxide sol-gel precursor solution is directly related to the degree of order of the titanium dioxide nanoparticle array produced. The titanium dioxide sol-gel solution is preferably mixed to 30 to 50% by volume of the reverse micelle solution, more preferably 40% by volume. When the titanium dioxide sol-gel solution is mixed at less than 30% by volume with respect to the reverse micelle solution, there is a problem in that the titanium dioxide nanoparticles are not formed in a regular arrangement, and when mixed in excess of 50% by volume, the titanium dioxide aggregates. There is a problem.

Step 4 is a step of coating the beads with the titanium dioxide-diblock copolymer nanostructure prepared in step 3. The coating is preferably carried out by treating the beads in a titanium dioxide-diblock copolymer nanostructure solution by treating them for 8 to 12 minutes in an ultrasonic apparatus, and more preferably for 10 minutes. If the treatment time is less than 8 minutes, there is a problem that the titanium dioxide particles may not be uniformly coated, if the treatment is more than 12 minutes there is a problem that the overall coating surface of a constant thickness can not be obtained because excessive energy is applied. .

In this case, the beads used may be any one selected from the group consisting of silica, alumina and metal oxides, and the present invention is not limited thereto, provided that the nanostructure having a nucleus / shell structure can be formed by coating titanium dioxide particles on the beads. .

Step 5 is a step of washing and drying the beads coated in step 4. This step removes the remaining solution of the coated beads and dries.

Step 6 is a step of removing the diblock copolymer by high temperature heat treatment of the beads coated with the titanium dioxide-diblock copolymer washed and dried in step 5. In the step 5, the nanostructures washed and dried in the furnace (furnace) is preferably carried out for 3 to 5 hours at 400 ~ 600 ℃ under conditions that the air is injected, it is preferably carried out at 500 ℃ for 4 hours More preferred. If the temperature of the calcining furnace is less than 400 ℃ there is a problem that the block copolymer is not removed well, if the temperature exceeds 600 ℃ there is a problem that the beads can be easily broken by heat shock. In addition, if the treatment time in the calcination furnace is less than 3 hours, there is a problem that the block copolymer is not removed well, if more than 5 hours there is a problem that waste time is continued in the state that the reduction is already completed. This step removes the polymer coating film comprising the biblock copolymers prepared in steps 3, 4 and 5 using heat to calcination.

Furthermore, the present invention provides a nanostructure of the nuclear / shell structure having a titanium dioxide prepared by the above method as a shell.

The nanostructure of the core / shell structure having titanium dioxide as a shell according to the present invention is capable of mixing and preparing raw materials at the molecular level due to the sol-gel process, which is a liquid phase method, thereby increasing the uniformity of the prepared particles and having a large surface area. There is an advantage that can produce particles of.

In addition,

Preparing a titanium dioxide sol-gel precursor solution by adding hydrochloric acid while dissolving the titanium dioxide precursor in ethanol or isopropanol solvent (step 1);

Supporting the beads on an aqueous potassium hydroxide solution to charge the beads (step 2);

Coating titanium dioxide on the beads by mixing the titanium dioxide sol-gel precursor solution and the beads prepared in steps 1 and 2 (step 3); And

It provides a method for producing a nanostructure of the nucleus / shell structure having a titanium dioxide shell including the step (step 4) of washing and drying the coated beads in step 3.

First, step 1 is a step of preparing a sol-gel precursor solution by dissolving the titanium dioxide precursor in ethanol or isopropanol solvent and adding hydrochloric acid or acetic acid. Titanium tetra-isopropoxide (TTIP), titanium tetrabutoxide, titanium alkoxide, etc. may be used as a titanium dioxide precursor, and ethanol, isopropanol, etc. may be used as a solvent. However, if the titanium precursor solution can be prepared is not limited thereto. It is more preferable to use concentrated hydrochloric acid as an acid, titanium tetraisopropoxide as a titanium dioxide precursor, and isopropanol as a solvent.

In the sol-gel precursor solution of titanium dioxide, it is preferable to adjust the pH to 1 to 3 by adding hydrochloric acid, and more preferably to adjust the pH to 2. If the pH is less than 1, there is a problem of excessively promoting the hydrolysis of the titanium precursor solution to cause the aggregation of titanium dioxide particles, and if the pH is exceeded 3, the difference in charge with the surface of the beads is small, so that the adsorption of titanium dioxide is reduced. have.

Step 2 is a step of supporting the beads on the surface of the beads by supporting the beads in an aqueous potassium hydroxide solution. At this time, the pH of the aqueous potassium hydroxide solution is preferably 7 to 8. If the pH of the beads is less than 7, there is a problem that the difference in the amount of charge decreases because the difference in hydrogen ion concentration becomes smaller, so that the degree of adsorption of the titanium dioxide sol-gel precursor solution to the beads decreases. There is a problem that local aggregation of titanium dioxide may occur due to excessive increase.

Step 3 is a step of coating the titanium dioxide on the beads by mixing the titanium dioxide sol-gel precursor solution and the beads prepared in Step 1 and Step 2. Titanium dioxide sol-gel precursor solution prepared in step 1 by using the difference in the charge amount of the hydrogen ion concentration of the titanium dioxide sol-gel precursor solution prepared in step 1 and the surface-charged beads in step 2, And the beads prepared in step 2 are directly coated by mixing.

In this case, the beads used may be any one selected from the group consisting of silica, alumina and metal oxides, and the present invention is not limited thereto, provided that the nanostructure having a nucleus / shell structure can be formed by coating titanium dioxide particles on the beads. .

Step 4 is a step of washing and drying the beads coated in step 3. This step removes the remaining solution of the coated beads and dries.

Furthermore, the present invention provides a nanostructure of the nuclear / shell structure having a titanium dioxide prepared by the above method as a shell.

The nanostructure of the core / shell structure having titanium dioxide as a shell according to the present invention is capable of mixing and preparing raw materials at the molecular level due to the sol-gel process, which is a liquid phase method, thereby increasing the uniformity of the prepared particles and having a large surface area. There is an advantage that can produce particles of.

Also,

Dissolving the amphiphilic diblock copolymer to prepare a reverse micelle solution (step 1);

Dissolving the titanium dioxide precursor in ethanol or isopropanol solvent and adding hydrochloric acid or acetic acid to prepare a sol-gel precursor solution (step 2);

Preparing a colloid by dissolving a gold nanoparticle precursor having hydrophilicity in one solvent selected from the group consisting of isopropanol, ethanol and methanol (step 3);

Preparing a titanium dioxide-diblock copolymer nanostructure by mixing the reverse micelle solution prepared in step 1 and the sol-gel precursor solution prepared in step 2 (step 4);

Preparing a gold-titanium dioxide-diblock copolymer nanostructure by mixing the gold nanoparticle precursor solution prepared in step 3 to the titanium dioxide-diblock copolymer nanostructure prepared in step 4 (step 5);

Coating the gold-titanium dioxide-diblock copolymer nanostructures prepared in step 5 on the beads (step 6);

Washing and drying the nanostructure coated with the gold-titanium dioxide-diblock copolymer prepared in step 6 (step 7); And

The core having the gold-titanium dioxide as a shell, which comprises the step of removing the double block copolymer by heating the nanostructure coated with the gold-titanium dioxide-diblock copolymer cleaned and dried in step 7 (step 8). It provides a method for producing a hybrid nanostructure of the shell structure.

First, step 1 is to prepare a reverse micelle solution by dissolving the amphiphilic diblock copolymer. It is preferable to introduce | transduce poly (styrene-block-ethylene oxide) in 0.1-1 weight% as an amphiphilic copolymer into a 1, 4- dioxane solvent, and it is more preferable that it is 0.5 weight%. If the content is less than 0.1% by weight, the titanium dioxide nanoparticles are not arranged, there is a problem that the hybrid nanoparticle array is not formed, if the content exceeds 1% by weight to obtain a single molecule micelle arrangement in the process of forming a thin film by coating There is a problem that is difficult.

Step 2 is a step of dissolving the titanium dioxide precursor in ethanol or isopropanol solvent and adding hydrochloric acid or acetic acid to prepare a sol-gel precursor solution. Titanium tetra-isopropoxide (TTIP), titanium tetrabutoxide, titanium alkoxide, etc. may be used as a titanium dioxide precursor, and ethanol, isopropanol, etc. may be used as a solvent. However, if the titanium precursor solution can be prepared is not limited thereto. It is more preferable to use concentrated hydrochloric acid as an acid, titanium tetraisopropoxide as a titanium dioxide precursor, and isopropanol as a solvent.

The acid opens or recesses the polyethylene oxide block portion of the copolymer of step 1, and simultaneously hydrolyzes the titanium dioxide precursor so that dense titanium dioxide nanoparticles can be formed on the opened or recessed polyethylene oxide portion. The titanium dioxide precursor is more preferably titanium tetraisopropoxide and isopropanol as a solvent.

Step 3 is a step of preparing a gold nanoparticle precursor solution by dissolving the hydrophilic gold nanoparticle precursor solution in one solvent selected from the group consisting of isopropanol, ethanol and methanol. As a gold nanoparticle precursor having hydrophilicity, it is preferable to use gold tetrachloride tetrachloride (HA (Cl) chloride trihydrate, HAuCl4.3H2O), but it is not limited thereto as long as it is a solvent and a gold precursor capable of preparing the gold nanoparticle precursor.

Step 4 is a step of preparing a titanium dioxide-diblock copolymer by mixing the reverse micelle solution prepared in step 1 and the sol-gel precursor solution prepared in step 2. The ratio of reverse micelle solution and titanium dioxide sol-gel precursor solution is directly related to the degree of order of the titanium dioxide nanoparticle array produced. The titanium dioxide sol-gel solution is preferably mixed to 30 to 50% by volume of the reverse micelle solution, more preferably 40% by volume. When the titanium dioxide sol-gel solution is mixed at less than 30% by volume with respect to the reverse micelle solution, there is a problem in that the titanium dioxide nanoparticles are not formed in a regular arrangement, and when mixed in excess of 50% by volume, the titanium dioxide aggregates. There is a problem.

Step 5 is a step of preparing a gold-titanium dioxide-diblock copolymer nanostructure by mixing the gold nanoparticle precursor solution prepared in step 3 to the titanium dioxide-diblock copolymer nanostructure prepared in step 4. The gold nanoparticle precursor solution is preferably mixed and adjusted so that the molar ratio (Au / EO) is 0.1 to 0.5 with respect to ethylene oxide (EO) in the reverse micelle solution, and more preferably 0.4. If the gold nanoparticle precursor solution has a molar ratio (Au / EO) of less than 0.1 to ethylene oxide (EO) in the reverse micelle solution, there is a problem that gold particles are not uniformly dispersed in each reverse micelle. There is a problem in that the particles are not included in the reverse micelles and gold particles are combined to form agglomerates.

Step 6 is to coat the gold-titanium dioxide-diblock copolymer nanostructures prepared in step 5 to the beads. The coating is preferably carried out by 8 to 12 minutes treatment in an ultrasonic apparatus by supporting the beads on the titanium dioxide-diblock copolymer nanostructure, and more preferably 10 minutes. If the treatment time is less than 8 minutes, there is a problem that the gold nanoparticles may not be uniformly coated, if the treatment for more than 12 minutes there is a problem that the overall coating surface of a constant thickness can not be obtained because excessive energy is applied.

In this case, the beads used may be any one selected from the group consisting of silica, alumina and metal oxide, and the gold-titanium dioxide particles may be coated on the beads to form a nanostructure having a nucleus / shell structure. Do not.

Step 7 is a step of washing and drying the beads coated in step 6. This step removes the remaining solution of beads and dries.

Step 8 is a step of removing the diblock copolymer by subjecting the nanostructure coated with the gold-titanium dioxide-diblock copolymer coated in step 7 to a high temperature to be heat-treated. The nuclear / shell structured nanostructure having the titanium dioxide-diblock copolymer nanostructure washed and dried in step 7 was introduced into a calcination furnace and heated at 400 to 600 ° C. under conditions in which air was injected. It is preferably carried out for 5 hours, more preferably at 500 ° C. for 4 hours. If the temperature of the calcination furnace is less than 400 ℃ there is a problem that the gold nanoparticle precursor is not reduced, if the temperature exceeds 600 ℃ there is a problem that the beads can be easily broken by heat shock. In addition, if the treatment time in the calcination furnace is less than 3 hours, only a portion of the gold nano precursors can be reduced, and if more than 5 hours, there is a problem that waste time is continued in the state that the reduction is already completed. This step is used to remove the polymer coating film comprising the biblock copolymer prepared in the steps 4, 5 and 6 using heat to calcination and gold nanoparticles in the form of precursors contained in the polymer coating film comprising the biblock copolymer Is reduced.

Furthermore, the present invention provides a hybrid nanostructure having a nucleus / shell structure having a gold-titanium dioxide prepared by the above method. The hybrid nanostructure of the nucleus / shell structure having a gold-titanium dioxide shell according to the present invention hybridizes titanium dioxide and gold nanoparticles and thus does not have a single titanium dioxide according to the induction effect of surface plasmon properties of these components. The advantage is that it can absorb visible light.

Also,

Preparing a titanium dioxide sol-gel precursor solution by adding hydrochloric acid while dissolving the titanium dioxide precursor in ethanol or isopropanol solvent (step 1);

Supporting the beads on an aqueous potassium hydroxide solution to charge the beads (step 2);

Coating titanium dioxide on the beads by mixing the titanium dioxide sol-gel precursor solution and the beads prepared in steps 1 and 2 (step 3);

Cleaning and drying the beads coated in step 3 (step 4);

Preparing a colloid by dissolving the gold nanoparticle precursor having hydrophilicity in one solvent selected from the group consisting of isopropanol, ethanol and methanol (step 5);

Supporting the titanium dioxide coated beads washed and dried in step 4 in the gold nanoparticle precursor solution prepared in step 5, and coating the gold particles using an ultrasonic generator (step 6);

Washing and drying the beads coated with the gold-titanium dioxide nanoparticles prepared in step 6 (step 7);

Reducing the gold nanoparticle precursor on the beads coated with the gold-titanium dioxide nanoparticles cleaned and dried in step 7 to gold nanoparticles (step 8); And

It provides a method for producing a hybrid nanostructure of the nucleus / shell structure having a shell of gold-titanium dioxide comprising the step of washing and drying the nanostructures prepared in step 8 (step 9).

First, step 1 is a step of preparing a sol-gel precursor solution by dissolving the titanium dioxide precursor in ethanol or isopropanol solvent and adding hydrochloric acid or acetic acid. Titanium tetra-isopropoxide (TTIP), titanium tetrabutoxide, titanium alkoxide, etc. may be used as a titanium dioxide precursor, and ethanol, isopropanol, etc. may be used as a solvent. However, if the titanium precursor solution can be prepared is not limited thereto. It is more preferable to use concentrated hydrochloric acid as an acid, titanium tetraisopropoxide as a titanium dioxide precursor, and isopropanol as a solvent.

As for the titanium dioxide precursor solution, it is preferable to adjust pH to 1-3 by adding hydrochloric acid, and it is more preferable to adjust pH to 2. If the pH is less than 1, there is a problem of excessively promoting the hydrolysis of the titanium precursor solution to cause agglomeration of titanium dioxide particles, and if more than 3, the charge difference with the surface of the beads is small, thereby reducing the adsorption of titanium dioxide. .

Step 2 is a step of supporting the beads on the surface of the beads by supporting the beads in an aqueous potassium hydroxide solution. At this time, the pH of the potassium hydroxide aqueous solution is preferably 7 to 8. When the pH of the potassium hydroxide solution is less than 7, there is a problem that the degree of adsorption of the titanium dioxide sol-gel precursor solution to the beads decreases because the difference in the hydrogen ion concentration on the surface of the beads decreases and the amount of charge decreases. There is a problem that local aggregation of titanium dioxide may occur due to excessive increase in the difference in charge amount. When the pH of the potassium hydroxide solution is less than 7, there is a problem that the degree of adsorption of the titanium dioxide sol-gel precursor solution to the beads decreases because the difference in the hydrogen ion concentration on the surface of the beads decreases and the amount of charge decreases. In this case, there is a problem that local aggregation of titanium dioxide may occur due to excessive increase of the difference in charge amount.

In this case, the bead may be any one selected from the group consisting of silica, alumina, and metal oxide, and the titanium dioxide particles may be coated on the beads to form nanostructures having a nucleus / shell structure.

Step 3 is a step of coating the titanium dioxide sol-gel precursor solution prepared in step 1 to the beads prepared in step 2. By using the difference in the charge amount of the titanium dioxide sol-gel precursor solution prepared in step 1 and the surface-charged beads in step 2, the titanium dioxide sol-gel precursor solution prepared in step 1 and the step 2 The beads prepared in the above were directly coated by mixing.

Step 4 is a step of washing and drying the beads coated in step 3. This step removes the remaining solution of the coated beads and dries.

Step 5 is a step of preparing a colloid by dissolving the gold nanoparticle precursor having hydrophilicity in one solvent selected from the group consisting of isopropanol, ethanol and methanol. As a gold nanoparticle precursor having hydrophilicity, it is preferable to use gold tetrachloride tetrachloride (HA (Cl) chloride trihydrate, HAuCl4.3H2O), but it is not limited thereto as long as it is a solvent and a gold precursor capable of preparing the gold nanoparticle precursor.

Step 6 is a step of coating the gold particles by supporting the titanium dioxide-coated beads washed and dried in step 4 in the gold nanoparticle precursor solution prepared in step 5. It is preferable to process for 8 to 13 minutes using an ultrasonic wave generator, and it is more preferable to process for 10 minutes. If the treatment time is less than 8 minutes, there is a problem that the gold nanoparticles may not be uniformly coated, if the treatment for more than 12 minutes there is a problem that the coating surface of a certain thickness can not be obtained because excessive energy is applied.

Step 7 is a step of washing and drying the beads coated in step 6. This step removes the remaining solution of beads and dries.

Step 8 is a step of reducing the gold nanoparticle precursor on the beads coated with the gold-titanium dioxide nanoparticles cleaned and dried in step 7 to gold nanoparticles. The step is preferably carried out by supporting the dried titanium dioxide-coated beads in ethanol dissolved in sodium borohydride to 0.005 ~ 0.015 molar concentration, the concentration of sodium borohydride is more preferably 0.01 mol. When the concentration of sodium borohydride is less than 0.005 mole, there is a problem that only a portion of the titanium dioxide precursor is reduced, and when it exceeds 0.015 mole, there is a problem that the gold nanoparticles are aggregated due to the too fast reduction rate.

Step 9 is a step of cleaning and drying the gold-titanium dioxide nanostructures prepared in step 8. Through this step, the remaining solution of the coated beads is removed and dried.

Furthermore, the present invention provides a hybrid nanostructure having a nucleus / shell structure having a gold-titanium dioxide prepared by the above method. The hybrid nanostructure of the nucleus / shell structure having a gold-titanium dioxide shell according to the present invention hybridizes titanium dioxide and gold nanoparticles and thus does not have a single titanium dioxide according to the induction effect of surface plasmon properties of these components. The advantage is that it can absorb visible light.

Hereinafter, the present invention will be described in more detail by way of examples. It should be noted, however, that the following examples are illustrative of the invention and are not intended to limit the scope of the invention.

Example 1 Preparation of Nanostructures Having Nucleus / Shell Structure I

Step 1. Amphibian  By dissolving the diblock copolymer Reverse mice  Step of preparing a solution

0.5 weight of poly (styrene-block-ethylene oxide) (PS-b-PEO, Mn, PS = 20,000 g / mol, Mn, PEO = 6,500 g / mol) in 1,4-dioxane (1,4-dioxane) Reverse micelle solutions were prepared by dissolving to a concentration of%.

Step 2. Preparing a Titanium Dioxide Sol-Gel Precursor Solution

Titanium dioxide precursor solution was prepared by adding 0.25 g of hydrochloric acid (37%) to 5 ml of isopropanol containing 0.71 g of titanium tetra-isopropoxide and stirring for 2 hours.

Step 3. Preparing a Titanium Dioxide-Diblock Copolymer Nanostructure

The titanium dioxide sol-gel precursor solution prepared in step 2 was mixed to 40 vol% with respect to the reverse micelle solution prepared in step 1 to prepare a titanium dioxide-diblock copolymer nanostructure.

Step 4. Titanium Dioxide-Diblock Copolymer Nanostructures On the bead  Coating step

1 mL of the titanium dioxide-diblock copolymer nanostructure prepared in step 3 was loaded with 0.1 g of silica beads having a diameter of 50 μm and subjected to an ultrasonic generator for 10 minutes, and the titanium dioxide-diblock copolymer nanostructures were silica beads. Coated on.

Step 5. Cleaning and Drying

In step 4, the remaining solution of the titanium dioxide-diblock copolymer nanostructure coated on the silica beads was removed using ultrapure water and dried in a 60 ° C. dry oven for 24 hours to carry out the nucleus / shell structure nanostructure having titanium dioxide as a shell. Was prepared.

Step 6. High Temperature Heat Treatment of the Cleaned and Dry Nanostructures

The silica / titanium dioxide-diblock copolymer nanostructure cleaned and dried in step 5 was introduced into a calcination furnace and heated at 500 ° C. for 4 hours under the condition of injecting air, and the core / shell structure having titanium dioxide as a shell. The nanostructure of was prepared.

Example 2 Preparation of Nanostructures Having Nucleus / Shell Structure II

Step 1.Preparing Titanium Dioxide Sol-Gel Precursor Solution

To 5 ml of isopropanol containing 0.71 g of titanium tetra-isopropoxide, 0.25 g of hydrochloric acid (37%) is added and stirred for 2 hours, followed by addition of concentrated hydrochloric acid to pH 2. A controlled titanium dioxide precursor solution was prepared.

Step 2. Charge the Bead Surface

0.1 g of silica beads having a diameter of 50 µm were loaded on 1 mL of an aqueous potassium hydroxide solution having a pH of 7 to 8 to charge the surface.

Step 3. On the bead  Coating titanium dioxide

The titanium dioxide sol-gel precursor was coated on the silica beads by mixing 1 mL of the titanium dioxide sol-gel precursor solution prepared in step 1 and 0.1 g of the silica beads having the surface-controlled charge in step 2 above.

Step 4. Cleaning and Drying

The remaining solution of the titanium dioxide coated silica beads prepared in step 3 was removed using ultrapure water and dried in a 60 ° C. dry oven for 24 hours to prepare a nucleus / shell structured nanostructure having titanium dioxide as a shell.

Example 3 Fabrication of Hybrid Nanostructure Having Nucleus / Shell Structure I

Step 1.Step of preparing reverse micelle solution

0.5 weight of poly (styrene-block-ethylene oxide) (PS-b-PEO, Mn, PS = 20,000 g / mol, Mn, PEO = 6,500 g / mol) in 1,4-dioxane (1,4-dioxane) Reverse micelle solutions were prepared by dissolving to a concentration of%.

Step 2. Preparing a Titanium Dioxide Sol-Gel Precursor Solution

Titanium dioxide precursor solution was prepared by adding 0.25 g of hydrochloric acid (37%) to 5 ml of isopropanol containing 0.71 g of titanium tetra-isopropoxide and stirring for 2 hours.

Step 3. Preparing a Gold Nanoparticle Precursor Solution

Gold nanoparticle precursor solution was prepared by dissolving gold tetrachloride (gold (III) chloride trihydrate, HAuCl 4 .3H 2 O) in isopropanol at 1.0 wt%.

Step 4. preparing titanium dioxide-diblock copolymer nanostructures

The titanium dioxide sol-gel precursor solution prepared in step 2 was mixed to 40 vol% with respect to the reverse micelle solution prepared in step 1 to prepare a titanium dioxide-diblock copolymer nanostructure.

Step 5. Preparing Gold-Titanium Dioxide-Diblock Copolymer Nanostructures

The gold-titanium dioxide-diblock copolymer nanostructure was mixed by mixing the ethylene oxide in the solution prepared in step 4 such that the molar ratio (Au / EO) of the gold nanoparticle precursor solution prepared in step 3 became 0.4. Prepared.

Step 6. Remove the gold-titanium dioxide-diblock copolymer nanostructures On the bead  Coating step

0.1 g of silica beads were loaded on 1 mL of the titanium dioxide-diblock copolymer nanostructure prepared in step 5, followed by treatment in an ultrasonic wave generator for 10 minutes, thereby treating the gold-titanium dioxide-diblock copolymer nanostructure with silica. The beads were coated.

Step 7. Cleaning and Drying

The remaining solution of the titanium dioxide-diblock copolymer nanostructure coated on the silica beads prepared in step 6 was removed using ultrapure water and dried in a 60 ° C. dry oven for 24 hours.

Step 8. High Temperature Heat Treatment of the Cleaned and Dry Nanostructures

The silica / titanium dioxide-diblock copolymer nanostructures washed and dried in the step 7 was introduced into a calcination furnace and heated at 500 ° C. for 4 hours under the condition of injecting air, thereby nuclei having gold-titanium dioxide as a shell. A hybrid nanostructure of shell structure was prepared.

Example 4 Fabrication of Hybrid Nanostructures Having Nucleus / Shell Structure II

Step 1.Preparing Titanium Dioxide Sol-Gel Precursor Solution

To 5 ml of isopropanol containing 0.71 g of titanium tetra-isopropoxide, 0.25 g of hydrochloric acid (37%) is added and stirred for 2 hours, followed by addition of concentrated hydrochloric acid to pH 2. A controlled titanium dioxide precursor solution was prepared.

Step 2. Bead  To charge the surface

An aqueous potassium hydroxide solution having a pH of 7 to 8 was loaded with silica beads having a diameter of 50 μm to charge the surface.

Step 3. On the bead  Coating titanium dioxide

The titanium dioxide sol-gel precursor solution prepared in step 1 was coated with a method of mixing silica beads having a surface charge controlled in step 2.

Step 4. Cleaning and Drying

The remaining solution of the titanium dioxide coated silica beads prepared in step 3 was removed using ultrapure water and dried.

Step 5. Preparing a Gold Nanoparticle Precursor Solution

Gold tetrachloride acid solution (HAuCl 4 · 3H 2 O) was dissolved in isopropanol at 1.0% by weight to prepare a gold nanoparticle precursor solution.

Step 6. Titanium Dioxide Coated Gold Nanoparticles On the bead  Coating step

1 g of the gold nanoparticle precursor solution prepared in step 5 was loaded with 0.1 g of titanium dioxide coated silica beads washed and dried in step 4, and then coated with gold nanoparticles by treatment in an ultrasonic wave generator for 10 minutes.

Step 7. Cleaning and Drying

The solution on the surface of the silica / gold-titanium dioxide structure prepared in step 6 was removed using ultrapure water and dried in a 60 ° C. dry oven for 24 hours.

Step 8. Reducing the Gold Nanoparticles

0.1 g of the silica / gold-titanium dioxide structure prepared in step 7 was immersed in 1 mL of a solution dissolved in ethanol at a 0.01 molar concentration of sodium borohydride (NaBH 4) for 10 minutes to reduce gold nanoparticles.

Step 9 . Washing and drying steps

The remaining solution on the surface of the silica / gold-titanium dioxide structure prepared in step 8 was washed and dried in a 60 ° C. dry oven for 24 hours to prepare a hybrid nanostructure having a nucleus / shell structure with gold-titanium dioxide as a shell.

Experimental Example 1 Surface Analysis of Nanostructure with Nucleus / Shell Structure

In order to confirm the characteristics of the surface of the nanostructure having a nucleus / shell structure according to the present invention, the nanostructure of the nucleus / shell structure prepared by Examples 1 to 4 was analyzed by field emission scanning microscope (SEM), and The results are shown in FIG.

As can be seen in Figure 2, as a result of the analysis of the enlarged part of the surface of Examples 1 and 3 using the amphiphilic double block copolymer was confirmed that the mesoporous structure is formed on the surface of the silica beads.

Experimental Example 2 Analysis of Optical Properties of Nanostructures with Nucleus / Shell Structure

In order to confirm the optical properties of the nanostructures prepared according to the present invention, for the nanostructures prepared by Examples 1 and 3, the absorbance is measured using a spectrophotometer (UV-Vis spectrometer) and the results 3 is shown.

As can be seen in Figure 3, the high peak commonly seen on the left side is believed to be due to the mesoporous titanium dioxide structure formed on each coating film. For Example 3, in which gold nanoparticles were introduced, a new peak was observed between 500 and 700 nm. This is due to the surface plasmon properties commonly observed in the reduced forms of precious metal nanoparticles with zero oxidation number. This shows that the gold nanoparticle precursors were reduced to gold nanoparticles by treating the coated silica beads in a calcination furnace.

Experimental Example 3 Measurement of Photocatalytic Activity of Nanostructure with Nucleus / Shell Structure

In order to determine the degree of photocatalytic activity of the nanostructure having a nucleus / shell structure according to the present invention, nanostructures prepared by Examples 1 and 3 in an ultraviolet cuvette containing 5 ppm methylene blue After immersion, the photocatalytic activity was measured by irradiating ultraviolet rays with a wavelength of 254 nm for 120 minutes and measuring the intensity (C / C0) of the absorption peak near 664 nm, and the results are shown in FIG. 4.

The relative absorbance decrease with respect to the absorbance of the methylene blue solution that changes over time is shown as a percentage in FIG. 4. Using the nanostructures prepared by Examples 1 and 3, which serve as photocatalysts, it could be seen that the decomposition efficiency of the methylene blue solution was remarkably increased in comparison with the case where the nanostructures were not used. In Example 1 it was confirmed that the relative absorbance of methylene blue was reduced from 100% to 40%, in Example 3 from 100% to 35%. From this, the nucleus / shell structure nanostructure having mesoporous titanium dioxide as a shell shows excellent photocatalytic activity, and the hybrid of nucleus / shell structure with gold-titanium dioxide with gold added to titanium dioxide as a shell Nanostructure was found to increase the efficiency even more. This is because electrons and holes generated by the charge transfer from the methylene blue in the excited state toward the catalyst or by irradiation with ultraviolet light promote the production of active materials such as radicals. Radicals generated in the nucleus / shell structure such as superoxide anion radicals are very strong oxidizing materials and can decompose organic materials very efficiently.

1: Bead
2: titanium dioxide (TiO2)
3: titanium dioxide layer (TiO2 layer)
4: hybrid gold-titanium dioxide (Au-TiO2)

Claims (24)

delete delete delete delete delete Preparing a titanium dioxide sol-gel precursor solution by adding hydrochloric acid while dissolving the titanium dioxide precursor in ethanol or isopropanol solvent (step 1);
Supporting the beads on an aqueous potassium hydroxide solution to charge the beads (step 2);
Coating titanium dioxide on the beads by mixing the titanium dioxide sol-gel precursor solution and the beads prepared in steps 1 and 2 (step 3); And
Method for producing a structure of the nucleus / shell structure having a titanium dioxide as a shell comprising the step (step 4) of washing and drying the beads coated in step 3.
7. The method of claim 6, wherein the hydrochloric acid in step 1 is added to adjust the pH of the titanium dioxide sol-gel solution to 1-3.
7. The method of claim 6, wherein the pH of the potassium hydroxide aqueous solution in step 2 is adjusted to 7-8.
7. The method of claim 6, wherein the bead of step 4 is any one selected from the group consisting of silica, alumina and metal oxides.
delete delete delete delete delete delete delete delete delete Preparing a titanium dioxide sol-gel precursor solution by adding hydrochloric acid while dissolving the titanium dioxide precursor in ethanol or isopropanol solvent (step 1);
Supporting the beads on an aqueous potassium hydroxide solution to charge the beads (step 2);
Coating titanium dioxide on the beads by mixing the titanium dioxide sol-gel precursor solution and the beads prepared in steps 1 and 2 (step 3);
Cleaning and drying the beads coated in step 3 (step 4);
Preparing a colloid by dissolving the gold nanoparticle precursor having hydrophilicity in one solvent selected from the group consisting of isopropanol, ethanol and methanol (step 5);
Supporting the titanium dioxide coated beads washed and dried in step 4 in the gold nanoparticle precursor solution prepared in step 5, and coating the gold particles using an ultrasonic generator (step 6);
Washing and drying the beads coated with the gold-titanium dioxide nanoparticles prepared in step 6 (step 7);
Reducing the gold nanoparticle precursor on the beads coated with the gold-titanium dioxide nanoparticles cleaned and dried in step 7 to gold nanoparticles (step 8); And
Method for producing a hybrid structure of the nucleus / shell structure having a gold-titanium dioxide as a shell comprising the step (step 9) of washing and drying the beads after the reduction of the step 8.
20. The method of claim 19, wherein in step 1, hydrochloric acid is added so that the pH of the titanium dioxide sol-gel solution is adjusted to 1 to 3 to prepare a hybrid structure of the nucleus / shell structure having a gold-titanium dioxide as a shell Way.
20. The method of claim 19, wherein the pH of the aqueous potassium hydroxide solution in step 2 is adjusted to 7 ~ 8, characterized in that the method for producing a hybrid structure of nuclear / shell structure having a gold-titanium dioxide as a shell.
20. The method of claim 19, wherein the bead of step 2 is any one selected from the group consisting of silica, alumina and metal oxides. . 20. The nucleus / shell having gold-titanium dioxide as a shell according to claim 19, wherein step 8 is carried out by supporting beads coated with titanium dioxide in ethanol in which sodium borohydride is dissolved in an amount of 0.005 to 0.015 molar concentration. Method for producing a hybrid structure of structure.
20. A hybrid structure of nuclear / shell structure having a gold-titanium dioxide as a shell, which is produced by the method of claim 19.

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