KR101172373B1 - Preparation method of Metal/TiO2 nanostructures - Google Patents

Abstract

The present invention provides a metal / titanium oxide nanostructure using an amphiphilic block copolymer as a template, specifically a method for producing a mesoporous metal / titanium oxide nanostructure, and a metal / titanium oxide nanostructure having improved photocatalytic activity, in particular The present invention relates to a platinum / titanium oxide nanostructure, and exhibits excellent photocatalytic activity, and thus may be usefully used in various fields such as environmentally friendly devices, photovoltaic cells, and optical sensors.

Description

Preparation method of metal-titanium oxide nanostructures {Preparation method of Metal / TiO2 nanostructures}

The present invention provides a metal / titanium oxide nanostructure using an amphiphilic block copolymer as a template, specifically a method for producing a mesoporous metal / titanium oxide nanostructure, and a metal / titanium oxide nanostructure having improved photocatalytic activity, in particular The present invention relates to a platinum / titanium oxide nanostructure.

Titanium oxide (TiO ₂ ) is a semiconducting metal oxide having three crystal structures, such as rutile, anatase, and brookite, and has unique characteristics depending on the crystal structure. Among them, rutile has good refractive index, hardness, and dielectric constant, and is mainly used for industrial, paint, white pigment, cosmetics, and food additives. It is widely used in paints, printing inks, plastics, paper, synthetic fibers, rubber, capacitors, crayons, electrical and electronic devices.

Nanocrystalline titanium oxide has been studied extensively in photocatalytic and photovoltaic applications because of its excellent photophysical and photochemical properties, but its limitation in its relatively large energy band gap (3.2V) limits its wide range of applications in the visible range. have. Metal / titanium oxide of the noble metal is introduced into the well-known method heterostructure to improve these shortcomings (Metal / TiO ₂₎ hybrid nanomaterial screen may be made of techniques, the metal / semiconductor two kinds of components, such as metal / titanium oxide Composite materials are known to express improved properties that single-component titanium oxides do not have due to their excellent physical properties due to the surface plasmon properties of metals, so they can be widely used in multicolored light emitting materials, photocatalysts, sensors, etc. have.

Typical methods of combining titanium oxide and metals include anion doping, platinum modification, and hybridization with noble metal. The noble metal and titanium oxide composites bonded in the above manner interfere with the recombination of photocharged charge carriers, resulting in a titanium oxide photocatalytic reaction with high quantum yield (Hoffmann, MR, Martin, ST, Choi W., Bahnemann, DW, Chem. Rev. (1995) 95, 69). For example, composite materials composed of dissimilar components such as platinum / titanium oxide (Pt / TiO ₂ ), silver / titanium oxide (Ag / TiO ₂ ), and gold / titanium oxide (Au / TiO ₂ ) have good mineral physical properties. It has been reported. In order to ensure the reliable functioning of such composites, the integration of well-formed and controlled multicomponents is an important factor, including photolithography, X-ray lithography, and electron beam lithography. Manufacturing methods have been used to implement hybrid metal / titanium oxide systems. The manufacturing of a composite material using this top-down approach has the advantage of forming a uniform pattern over a large area, but requires expensive lithography equipment and due to the limitation of the light source used in the lithography equipment. Due to this, it is difficult to form a regular pattern of several nanometers to several tens of nanometers. Therefore, in order to manufacture a metal / titanium oxide hybrid nanostructure, it may be advantageous to use a bottom-up approach instead of a top-down method such as lithography.

On the other hand, mesoporous titanium oxide is widely used in the field of light emitting materials, photocatalysts, sensors, etc. based on the characteristics that the accessibility of materials and the surface area are considerably increased due to the generation of pores, compared to the general titanium oxide nanoparticles or crystals. It is a material that is expected to apply. Therefore, if metal / titanium oxide nanostructures are prepared by introducing metal into mesoporous titanium oxide, the mesoporous titanium oxide may be combined with the functions of expressing metal components to be used as an excellent photoactive material. Development of simpler and less expensive processes is essential for a wide range of applications of metal / mesoporous titanium oxide materials.

Therefore, the inventors of the present invention provide a metal / titanium oxide nanostructure using an amphiphilic block copolymer as a template, specifically, a method for producing a mesoporous metal / titanium oxide nanostructure, and a metal / titanium oxide nanostructure having improved photocatalytic activity, In particular, it was found that the platinum / titanium oxide nanostructures exhibited enhanced photocatalytic activity and completed the present invention.

It is an object of the present invention to provide a method for producing a metal / titanium oxide nanostructure, particularly a mesoporous metal / titanium oxide nanostructure, using an amphiphilic block copolymer.

Still another object of the present invention is to provide a metal / titanium oxide nanostructure, in particular a platinum / titanium oxide nanostructure, having improved photocatalytic activity prepared by the above method.

In order to achieve the above object, the present invention comprises the steps of preparing a reverse micelle solution by dissolving the block copolymer in a solvent (step a); Dissolving the metal nanoparticle precursor in a solvent to prepare a colloidal solution (step b); Preparing a titanium oxide sol-gel precursor solution (step c); Mixing the reverse micelle solution prepared in step a, the colloidal solution prepared in step b and the sol-gel precursor solution prepared in step c in different ratios with respect to the reverse micelle solution prepared in step a) Step d) spin-coating the substrate after mixing to produce a metal / titanium oxide / block copolymer thin film from nanoparticle array to mesoporous nanostructures (step e); And post-treating the thin film prepared in step e to remove the block copolymer and reducing the metal precursor to the metal (step f), thereby providing a method for producing a metal / titanium oxide hybrid nanostructure. The metal / titanium oxide nanostructures produced by the process have improved photocatalytic activity.

Metal / titanium oxide nanostructures, in particular mesoporous platinum / titanium oxide nanostructures, using the amphiphilic block copolymers according to the present invention, are easy to manufacture using block copolymers and are sensitive to light oxidation. Since titanium and metal are contained, it shows excellent photocatalytic activity, which can be usefully used in various fields such as environmentally friendly devices, photovoltaic cells, and optical sensors.

1 is a schematic diagram showing a manufacturing process of the platinum / titanium oxide nanostructures according to the present invention.
Figure 2 is a graph showing the absorbance analysis results of Example 1 and Comparative Example 1 thin film according to the present invention.
3 and 4 are atomic force microscope (AFM) photographs showing nanostructures of Example 1 and Comparative Example 1 according to the present invention, respectively (before ultraviolet irradiation: Examples 1 to 3 (a), (b), ( c), Comparative Examples 1-4 (a), (b), (c); after ultraviolet irradiation: Examples 1-3 (d), (e), (f), Comparative Examples 1-4 ( d), (e), (f)).
Figure 5 is a scanning electron microscope (TEM, Figure 5 (a), 5 (b), 5 (c)) photograph showing the internal structure of Example 1 according to the present invention, line scan X-ray spectroscopy (EDS line scan 5 (a) and (a-1), 5 (b) and (b-1), 5 (c) and (c-1)) photographs and X-ray spectroscopy (EDS, FIG. 5 (a-) 2), 5 (b-2), and 5 (c-2)) results.
Figure 6 is a graph showing the light absorption ratio of the absorption peak at 318 nm of the thin film prepared by the production method of Example 1 and Comparative Example 1 according to the present invention.
7 is a schematic representation of a platinum / titanium oxide photocatalytic activity mechanism.

The present invention,

(a) dissolving the self-assembling diblock copolymer in a solvent to prepare a reverse micelle solution;

(b) mixing the metal precursor with an alcohol solvent to prepare a colloidal solution;

(c) mixing the titanium oxide precursor with an alcohol solvent to prepare a sol-gel precursor solution; And

(d) the colloidal solution prepared in step (b) and the sol-gel precursor solution prepared in step (c) are added to the reverse micelle solution prepared in step (a) and mixed to mix the colloidal solution and the sol-gel precursor solution. It provides a method for producing a metal-titanium oxide nanostructure comprising a; preparing a reverse micelle solution containing.

In the present invention, after the step (d),

(e) coating a reverse micelle solution containing a colloidal solution and a sol-gel precursor solution onto a substrate to produce a metal-titanium oxide-block copolymer thin film; And

(f) further treating the thin film to remove the self-assembled copolymer.

The metal-titanium oxide nanostructures prepared through the preparation method of the present invention exhibit excellent photocatalytic activity.

Hereinafter, the present invention will be described in detail step by step.

First, the step (a) according to the present invention is a step of preparing a reverse micelle solution by dissolving the self-assembled diblock copolymer in a solvent, an amphiphilic block copolymer may be used as the self-assembled diblock copolymer.

The block copolymer of step (a) may be selectively dissolved in only one block to form reverse micelles in solution.

In the present invention, the block copolymer is poly (styrene-block-ethylene oxide) which is an amphiphilic diblock copolymer (Poly (styrene-b-ethylene oxide, PS-b-PEO), polystyrene-block-poly (4-vinylpyridine) (PS-b-P4VP), polystyrene-block-poly (2-vinylpyridine) (PS-b-P2VP), poly (styrene-block-methyl methacrylate) (Poly (styrene-b-methyl methacrylate), Poly (styrene-b-acrylic acid), poly (butadiene-block-ethylene oxide) (Poly (butadiene-b-ethylene oxide), and poly (propylene-block-ethylene oxide) ( Poly (propylene-b-ethylene oxide) and the like can be used, but is not limited to the amphiphilic block copolymer.

The solvent is preferably toluene, chloroform, tetrahydrofuran, dimethylformamide (DMF, dimethylformamide), benzene, cyclohexane, hexane or ethyl acetate, which selectively dissolves the polystyrene block in the diblock copolymer. The solvent may be formed as long as it can form reverse micelles.

Furthermore, the reverse micelle solution of step (a) may comprise 0.1 to 1.5% by weight of the block copolymer. If the block copolymer is less than 0.1% by weight, the titanium oxide nanoparticles may not be arranged so that a hybrid nanoparticle array may not be formed. When the block copolymer is more than 1.5% by weight, the block copolymer may be formed in a thin film forming process by spin coating. There is a problem that it is difficult to obtain a molecular micelle array.

Next, step (b) according to the present invention is a step of dissolving the metal nanoparticles in a solvent to prepare a metal precursor solution.

In the present invention, the metal precursor colloidal solution of step (b) may contain 0.1 to 5% by weight of the metal precursor, more specifically 0.1 to 3% by weight. When the concentration is low, the content of alcohol when mixed with reverse micelle solution There is a fear that the problem of poor solubility of the polymer due to the excessive, and when the concentration is high, there is a fear that a problem of failing to obtain a uniform metal precursor solution due to the metal precursor content beyond the solubility of the alcohol solvent.

Platinum, gold, silver, cobalt, iron, palladium, copper, cadmium, ruthenium, nickel, manganese, etc. may be used as the metal of step (b) in the present invention, and any metal precursor may be used as long as the metal salt is soluble in alcohols. It is possible. More specifically, the platinum precursor may be used as a precursor such as platinum chloride, chloroplatinic acid or platinum nanoparticles modified with a hydrophilic ligand. At this time, the hydrophilic ligand is preferably an alcohol group (-OH), a carboxylic acid group (-COOH) or the like.

Propanol, ethanol, methanol, butanol, and the like may be used as the solvent of step (b), and particularly isopropanol may be used. The dissolved metal as described above may be selectively bonded to the hydrophilic block portion of the block copolymer.

In this case, in the case of dissolving the metal nanoparticles in the above-described solvent, the content of the metal nanoparticles can be adjusted within an appropriate range in consideration of the molecular weight of the hydrophilic polymer and the amount of the titanium oxide sol-gel precursor used in the following step (c). have. Preferred content of the metal nanoparticles is described in detail in step (d) below.

Next, step (c) according to the present invention is to prepare a titanium oxide sol-gel precursor solution. The sol-gel precursor solution may be prepared by dissolving the titanium oxide precursor in a solvent, followed by dilution and stirring with a strong acid. Titanium alkoxide may be used as the titanium oxide precursor, and more specifically, titanium methoxide, titanium ethoxide, titanium tetra-isopropoxide (TTIP), and titanium butoxide (titanium). butoxide) and titanium tert-butoxide may be used, and ethanol, isopropanol, or the like may be used as the solvent.

The acid opens or recesses the hydrophilic block portion of the block copolymer of step (a) and simultaneously hydrolyzes the titanium oxide precursor to form a dense titanium oxide nanostructure in the open or recessed hydrophilic block portion. . At this time, the acid may be concentrated hydrochloric acid, glacial acetic acid, nitric acid, formic acid, and the like, and may be used by mixing two or more of them, but is not limited thereto.

Step (e) according to the present invention is the reverse micelle solution prepared in step (a), the metal nanoparticle precursor solution prepared in step (b) and the titanium oxide sol-gel precursor prepared in step (c) After the step (d) of mixing the solution, spin coating the substrate to prepare a metal / titanium oxide / block copolymer thin film.

In the present invention, a variety of substrates may be used as the substrate, such as a silicon wafer, glass, quartz, a metal substrate such as aluminum or copper, or a plastic substrate such as PET film.

In step (e), the reverse micelle solution, the metal nanoparticle precursor solution and the titanium oxide sol-gel precursor solution have a constant content of metal nanoparticles in view of the orderedness of the metal / titanium oxide hybrid nanostructures to be produced. It is preferable to mix to have a ratio. For example, first, the molar ratio (Pt / EO) of the metal nanoparticles to ethylene oxide, which is a hydrophilic block in the poly (styrene-block-ethylene oxide) reverse micelle solution, is preferably mixed so as to be 0.1 to 0.5, and the step (d ), The titanium oxide sol-gel precursor solution of step (c) may be mixed in a volume ratio of 10 to 80%, more specifically 40 to 80% relative to the reverse micelle solution of step (a).

If the molar ratio (Pt / EO) is less than 0.1, there is a problem in that the dispersion of metal particles in each reverse micelle is not uniform. If the molar ratio (Pt / EO) is more than 0.5, the particles are not included in the reverse micelle and bound together to form agglomerates. There is.

Furthermore, as the ratio of the titanium oxide sol-gel precursor solution to the reverse micelle solution of step (a) increases, the content of titanium oxide selectively binding to the hydrophilic block portion of the block copolymer is changed, and thus the nanostructure. Modifications of the polymers lead to the production of various metal / titanium oxide / block copolymer thin films, ranging from nanoparticle arrays to mesoporous nanostructures. However, as the ratio of the titanium oxide sol-gel precursor solution to the reverse micelle solution increases, the content of the titanium oxide precursor is increased because the metal / titanium oxide hybrid structure leaves the block copolymer template and aggregates with neighboring composite precursors to form agglomerates. It is preferable to mix so that it may have a fixed ratio with respect to this block copolymer amount.

Step (f) is a step of post-treatment of the thin film prepared in step (e) to remove the block copolymer and at the same time reducing the metal precursor to metal, wherein the post-treatment is any one of oxygen plasma exposure, heat treatment or ultraviolet irradiation. Can be.

The present invention also provides a metal / titanium oxide nanostructure having improved photocatalytic activity prepared by the above-described manufacturing method. The nanostructures can be, for example, metal / titanium oxide nanoparticle arrays, mesoporous metal / titanium oxide nanostructures, more specifically platinum / titanium oxide nanoparticle arrays, mesoporous platinum / titanium oxide nanostructures And the like.

The metal / titanium oxide hybrid nanostructures according to the present invention have excellent photocatalytic activity, in particular by hybridization of platinum. In order to examine the photocatalytic activity of the hybrid nanostructures, a comparison of experiments in which the platinum / titanium oxide thin films prepared in Example 1 and Comparative Example 1 of the present invention and the measurement of the decomposition of paranitrophenols of the titanium oxide thin films was started, the photocatalyst experiment was started. After 5 hours, it can be seen that in Example 1, the photocatalytic activity was almost the same or increased significantly compared to Comparative Example 1.

Therefore, the hybrid nanostructure according to the present invention is a photocatalyst, and can be usefully used in fields such as environmentally friendly devices, photovoltaic cells, and optical sensors.

Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are merely to illustrate the invention, the content of the present invention is not limited by the following examples.

Example 1 Preparation of Platinum / Titanium Oxide Hybrid Nanostructure

Step 1. Amity Block copolymer  Containing Reverse mice  Solution preparation

Polystyrene-block-polyethylene oxide (PS-b-PEO, Mn, _PS = 20000, Mn, _PEO = 6500 g / mol, Polymer Source, Inc.) was dissolved in toluene at a concentration of 1.0% by weight of reverse micelles The solution was prepared.

Step 2. Preparation of Platinum Precursor Nanoparticle Solution

A platinum chloride solution was prepared by dissolving the platinum chloride salt in isopropanol at a concentration of 1.0% by weight.

Step 3. Preparation of titanium oxide sol-gel precursor solution

To 1.903 g of isopropanol dissolved in 0.2 g of titanium tetra-isopropoxide (Aldrich), 0.254 g of glacial acetic acid was added and stirred for 6 hours, followed by addition of 0.242 ml of isopropanol. Stirring for more than a time to prepare a titanium oxide precursor solution.

Step 4. Platinum / Titanium Oxide / Block copolymer  Manufacture of thin film

The molar ratio (Pt / EO) of the platinum nanoparticles is 0.3 to the ethylene oxide of the reverse micelle solution of step 1, and the titanium oxide sol-gel precursor solution is 10% to the reverse micelle solution, respectively. Mix at a volume ratio of 80%. The reverse micelle solution, the platinum chloride solution and the titanium oxide sol-gel precursor solution were mixed and stirred for one week, and then added to a silicon substrate and spin-coated at 2500 rpm for 120 seconds to prepare a platinum / titanium oxide / block copolymer thin film. It was.

Step 5. Platinum / Titanium Oxide by Ultraviolet Irradiation hybrid  Nanostructure Manufacturing

A platinum / titanium oxide nanostructure was prepared by irradiating the thin film of step 4 with ultraviolet rays of 254 nm wavelength at 25 J / cm 2 for 7 hours to remove the block copolymer and reducing the platinum precursor to platinum (FIG. 1).

Comparative Example 1 Preparation of Titanium Oxide Nanostructure

Titanium oxide nanostructures containing no platinum nanoparticles were prepared in the same manner as in Example 1, except that step 2 of preparing the platinum nanoparticle solution of Example 1 was omitted.

Experimental Example 1 Analysis of Absorbance of Platinum / Titanium Oxide / Block Copolymer Thin Film and Titanium Oxide / Block Copolymer Thin Film

In order to determine the absorbance by irradiating ultraviolet-visible lines to the thin films of Example 1 and Comparative Example 1 according to the present invention, the absorbance was measured using an ultraviolet-visible spectrophotometer (Vrospectometer, Varian, Cary 500), and the results 2 is shown.

Referring to the ultraviolet-visible absorption spectrum of FIG. 2, the absorption of titanium oxide increases as the amount of the titanium oxide sol-gel precursor solution is increased from 40% to 80% at 10% by volume for the reverse micelle solution. In Comparative Example 1, the thin film of Comparative Example 1 exhibited a very weak absorption of light in the wavelength range of 350 nm or more, that is, in the visible range, whereas the characteristic absorption peak of the ash ash titanium was apparent in the 250-300 nm wavelength range, that is, in the ultraviolet region. As can be seen, as a result of comparative analysis of the spectral results of the thin films of Comparative Example 1 and Example 1, it can be seen that the absorption of titanium oxide significantly increased not only in the ultraviolet region but also in the visible range of 350 nm or more due to the addition of platinum.

Experimental Example 2 Arrangement Analysis of Nanostructures with or without Platinum or Titanium Oxide Content

The nanostructures of Example 1 and Comparative Example 1 according to the present invention were photographed by using an atomic force microscope (AFM, DI / Veeco, USA), and the results are shown in FIGS. 3 and 4.

3 (a), (b), (c) is a photograph taken before the ultraviolet irradiation of the platinum / titanium oxide hybrid nanostructure of Example 1, Figures 3 (a), (b), (c) Appearance of platinum / titanium oxide / block copolymer nanostructures when the amount of titanium oxide sol-gel precursor solution is added in 10%, 40%, and 80% volume ratios to the reverse micelle solution together with the same amount of platinum colloid solution 4 (a), (b) and (c) are photographs of comparative examples thereof. In these photographs, the lighter part represents the polystyrene block and the darker part represents the polyethylene oxide block. As the amount of titanium oxide sol-gel precursor solution added to the reverse micelle solution increased, the matrix of the thin film was inverted from the polystyrene block to the polyethylene oxide block, and the amount of the titanium oxide sol-gel precursor solution was observed. By increasing, it was confirmed that a titanium oxide / block copolymer thin film or a platinum / titanium oxide / block copolymer thin film forming a reverse structure can be obtained. This phenomenon is a phenomenon in which the alcohol component contained in the titanium oxide sol-gel precursor is induced by reconstructing the polyethylene oxide block to open reverse micelles, and the alcohol component contained in the titanium oxide precursor plays an important role in the arrangement of the titanium oxide structure. It can be seen that.

3 (d), (e) and (f) are photographs showing the arrangement of Example 1 in which the block copolymer was removed by irradiating ultraviolet rays to the thin films of FIGS. 3 (a), (b) and (c) for 7 hours, respectively. 4 (d), (e) and (f) are photographs of comparative examples thereof. In these photographs, only the polystyrene block portion of the titanium oxide / block copolymer thin film or the platinum / titanium oxide / block copolymer thin film is removed and the polyethylene oxide block portion remains as it is. It can be seen that the precursor is located in the polyethylene oxide block.

In addition, when the amount of the titanium oxide sol-gel precursor solution was added in a volume ratio of 10%, 40%, and 80% with respect to the reverse micelle solution, the nanoparticle arrays (Fig. 3 (d) and Fig. 4 (d)) after ultraviolet irradiation, respectively. ), Along with the disordered nanowire structures, some mesoporous nanostructures (FIG. 3 (e), 4 (e)), mesoporous nanostructures (FIG. 3 (f), 4 (f)) It was confirmed that the formation, from which it can be seen that the shape and arrangement of the titanium oxide structure can be controlled by changing the relative concentration of the titanium oxide precursor.

Furthermore, when comparing FIG. 3 and FIG. 4, FIG. 3 shows a case where all other experimental conditions except platinum are present, for example, the amount of reverse micelle solution, the amount of titanium oxide precursor solution, and the alcohol content are the same. In comparison with 4, it shows a hexagonal array with a relatively uniform domain size, indicating that the addition of platinum affects the uniform hexagonal alignment of the platinum / titanium oxide hybrid nanostructures.

Experimental Example 3 Analysis of Internal Structure of Platinum / Titanium Oxide Hybrid Nanostructure

The internal structure of Example 1 according to the present invention was analyzed using a transmission electron microscope (TEM, JEOL JSM2100-F) equipped with an X-ray spectroscopy (EDS), and the results are shown in FIG. 5.

In order to use the transmission electron microscope, platinum / titanium oxide thin film was coated on a platinum / titanium oxide thin film, and 35% by weight of poly acrylic acid was dropped, followed by heat treatment at 70 ° C. for 12 hours. After removing the thin film and polyacrylic acid together, the specimen was prepared by coating a platinum / titanium oxide thin film obtained by dissolving polyacrylic acid in water and coating it on a copper grid.

As a result of transmission electron microscopy, when the titanium oxide precursor solution was added in 10% by volume to the reverse micelle solution, the domain was composed of hexagonal system, and particles which appeared to be inorganic materials were located in this domain (FIG. 5). When the titanium oxide precursor solution is added in 40% by volume, a structure is formed in which the domains are connected and some mesopores are formed, and the inside of the domain or the periphery of the mesopores in which the particles appear to be inorganic materials are connected. It can be seen that the position (see Fig. 5 (b)), when the titanium oxide precursor solution is increased by 80% by volume, the mesoporous structure is formed and the particles appear to be mainly located around the mesopore (See FIG. 5 (c)). The photograph of such a platinum / titanium oxide thin film structure is a result consistent with those of FIGS. 3 (d), (e), and (f).

In addition, as a result of a line scan by X-ray spectroscopy, when a titanium oxide precursor solution was added in a 10% volume ratio to a reverse micelle solution, platinum (blue line) and titanium oxide (titanium-red line, oxygen-light green line) ) Is observed in the domain consisting of hexagonal systems (see FIGS. 5 (a) and 5 (a-1)), but when the titanium oxide precursor solution is added in a 40% volume ratio, the peaks of platinum and titanium oxide When the domains are joined (see Figures 5 (b) and 5 (b-1)), the peaks of platinum and titanium oxide are mainly observed around mesopores when the titanium oxide precursor solution is increased to 80% by volume. (See FIG. 5 (c) and FIG. 5 (c-1)). This is a result consistent with the AFM photo analysis, and it can be seen that the thin film prepared from the measurement results by the X-ray spectroscopy apparatus with platinum and titanium oxide in the thin film manufactured (Fig. 5 (a- 2), 5 (b-2) and 5 (c-2)).

Experimental Example 4 Analysis of Photocatalytic Activity

In order to determine the degree of photocatalytic activity of the nanostructures of Example 1 and Comparative Example 1 according to the present invention, ultraviolet rays were irradiated to Example 1 and Comparative Example 1, and a reduction degree of p -nitrophenol was measured. The photocatalytic activity of the thin film was measured through.

An ultraviolet cuvette containing 10 ppm paranitrophenol was immersed in the thin films of Example 1 and Comparative Example 1 and irradiated with ultraviolet rays at a wavelength of 254 nm for a predetermined time, and the intensity ratio of the absorption peak at 318 nm (I / I ₀ ) is analyzed and shown in FIG. 6.

When the titanium oxide precursor solution was added at a volume ratio of 10% and 40% with respect to the reverse micelle solution, it was confirmed that the decomposition effect of paranitrophenol was significantly increased by the addition of platinum, even when 10% of the titanium oxide precursor solution was added. It can be seen that the decomposition rate of paranitrophenol in the titanium oxide thin film when the platinum / titanium oxide thin film and the titanium oxide precursor solution were added 40%.

In addition, when 80% of the titanium oxide precursor solution was added, the decomposition of paranitrophenol by the titanium oxide thin film or the platinum / titanium oxide thin film tended to increase rapidly compared to when 10% or 40% was added. The thin film completely degraded about 75% of the paranitrophenol solution. In this case, an exceptional tendency of increasing photocatalytic activity due to the addition of platinum was not clearly observed, which is considered to be a result due to the characteristics of the mesoporous titanium oxide structure.

The mechanism for the photocatalytic activity can be seen in the energy band diagram (see FIG. 7). The reason why the photocatalytic property of the thin film of Example 1 is increased is that the photoelectron moves from titanium oxide to platinum and thus the photoelectron ( This is because it prevents recombination between electron-hole pairs. Holes are required to recombine with electrons, and the concentration of holes is so low that they are more likely to combine with the reduction reactions that form active materials such as superoxide anion radicals. The superoxide anion radical is a very strong oxidizing material and can decompose organic materials very efficiently.

Claims (20)

(a) dissolving the self-assembling diblock copolymer in a solvent to prepare a reverse micelle solution;
(b) mixing the platinum precursor with an alcohol solvent to prepare a colloidal solution;
(c) mixing the titanium oxide precursor with an alcohol solvent to prepare a sol-gel precursor solution; And
(d) mixing the colloidal solution prepared in step (b) and the sol-gel precursor solution prepared in step (c) with the reverse micelle solution prepared in step (a) to contain the colloidal solution and the sol-gel precursor solution. Preparing a reverse micelle solution;
In step (d), mesoporous platinum-oxidation, characterized in that the titanium oxide sol-gel precursor solution of step (c) is mixed in a volume ratio of 40 to 80% with respect to the reverse micelle solution of step (a). Method for producing titanium nanostructures.
The method of claim 1,
(e) coating a reverse micelle solution containing a colloidal solution and a sol-gel precursor solution onto a substrate to produce a metal-titanium oxide-block copolymer thin film; And
(f) post-treating the thin film to remove the self-assembling copolymer, further comprising the step of producing a mesoporous platinum-titanium oxide nanostructure.
The method of claim 1,
Method for producing a mesoporous platinum-titanium oxide nanostructure, characterized in that the self-assembling diblock copolymer of step (a) is an amphiphilic diblock copolymer.
The method of claim 3,
The amphiphilic diblock copolymer is poly (styrene-block-ethylene oxide) (Poly (styrene-b-ethylene oxide, PS-b-PEO), polystyrene-block-poly (4-vinylpyridine) (PS-b- P4VP), polystyrene-block-poly (2-vinylpyridine) (PS-b-P2VP), poly (styrene-block-methyl methacrylate) (Poly (styrene-b-methyl methacrylate), poly (styrene-block- Poly (styrene-b-acrylic acid), poly (butadiene-block-ethylene oxide) (Poly (butadiene-b-ethylene oxide) and poly (propylene-block-ethylene oxide) (Poly (propylene-b-ethylene method of producing a mesoporous platinum-titanium oxide nanostructure, characterized in that it is selected from the group consisting of.
The method of claim 1,
The solvent of step (a) is a method for producing a mesoporous platinum-titanium oxide nanostructure, characterized in that to selectively dissolve only one block of the diblock copolymer.
The method of claim 1,
The solvent is any one selected from the group consisting of toluene, chloroform, tetrahydrofuran (THF), dimethylformamide (DMF, Dimethylformamide), benzene, cyclohexane, hexane and ethyl acetate. Method for producing a mesoporous platinum-titanium oxide nanostructure, characterized in that.
delete The method of claim 1,
Method for producing a mesoporous platinum-titanium oxide nanostructure, characterized in that the reverse micelle solution of step (a) contains 0.1 to 1.5% by weight of the self-assembling diblock copolymer.
The method of claim 1,
Method for producing a mesoporous platinum-titanium oxide nanostructure, characterized in that the platinum precursor colloidal solution of step (b) contains 0.1 to 5% by weight of a metal precursor.
The method of claim 1,
Mesoporous platinum-titanium oxide nanostructures, characterized in that the alcohol solvent used in steps (b) and (c) is at least one solvent selected from the group consisting of propanol, methanol, ethanol and butanol or a mixed solvent thereof. Manufacturing method.
The method of claim 1,
A method for producing a mesoporous platinum-titanium oxide nanostructure, wherein the titanium oxide precursor is titanium alkoxide.
The method of claim 1,
Step (c)
(c1) placing a titanium oxide precursor in an alcohol solvent and adding an acid thereto; And
(c2) further adding, diluting and mixing the alcohol solvent to prepare the mesoporous platinum-titanium oxide nanostructure.
The method of claim 12,
A method for producing a mesoporous platinum-titanium oxide nanostructure, characterized in that the acid is one acid selected from the group consisting of glacial acetic acid, hydrochloric acid, nitric acid and formic acid, or two or more mixed acids selected from the group.
The method of claim 1,
In step (d), the mesoporous platinum-oxidation is characterized in that the molar ratio (Pt / EO) of the metal of step (b) to the ethylene oxide of the reverse micelle solution of step (a) is 0.1 to 0.5. Method for producing titanium nanostructures.
delete delete The method of claim 2,
A method for producing a mesoporous platinum-titanium oxide nanostructure, characterized in that the substrate is selected from the group consisting of silicon wafers, glass, quartz, metal substrates and plastic substrates.
The method of claim 2,
The post-treatment in step (f) is selected from the group consisting of ultraviolet irradiation, oxygen plasma exposure and heat treatment.
delete Mesoporous platinum-titanium oxide nanostructures having improved photocatalytic activity prepared by the method of claim 1.

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