KR100975655B1 - Nanostructure and synthetic method thereof using bivalve shell - Google Patents

Abstract

The present invention relates to a nanostructure using a shell, which is a representative biomaterial existing in nature, and a method of manufacturing the same. More particularly, a metal oxide is used as a precursor, and a metal is contained in the bivalve shell. The present invention relates to a metal oxide 1D (one-dimensional) nanostructure and a method for manufacturing the same, characterized in that the oxide is supported and heat-treated.

The present invention has a high conversion yield, provides a nanostructure capable of mass production, and is easy to separate and recover the nanostructure, environmentally friendly and low process cost can be utilized as a source technology of 1D nanostructure material industry Has the effect.

Metal oxide, 1D (one-dimensional) nanostructures, nanorods, nanowires, nanodisks, shells

Description

Nanostructure and synthetic method using bivalve shells

The present invention relates to a nanostructure using a shell, which is a representative biomaterial existing in nature, and a method for manufacturing the same. More specifically, the metal oxide is used as a precursor, and the metal oxide is supported inside the bivalve shell. It relates to a metal oxide 1D nanostructure and a method for producing the same, characterized in that the heat treatment.

Nanostructures can be categorized into one-dimensional nanomaterials such as nanorods and nanotubes, nanoparticles of zero dimension, and nanomaterials of two-dimensional nanofilms. They are used in semiconductor, bio, optical, environmental devices, and solar cells. It is used. Among the 1D nanostructures, titanium-based nanorods are used as electrode materials for dye-sensitized solar cells, and tungsten-based nanorods are widely used as sensors for detecting NOx and SOx materials.

Various methods have been studied to control the shape, size, and arrangement of 1D nanostructures. Methods of using inorganic materials or polymers as templates [CaO, Liu, Adv. Colloid Interface Sci., 2008, 136, pp 45-64] and using capping reagents in solution phase [Zhang et al., Angew. Chem. Int. Ed., 2005, 44, pp 3466-3470] and vapor phase method through supersaturation control [Ouyang et al., Adv. Mater., 2006, 18, pp 1437-1440 and methods using the Vapor-Liquid-Solid (VLS) mechanism [Fan et al., Small, 2006, 2, pp 700-717]. However, these methods require relatively expensive precursors and synthesis equipment and are synthesized under a limited atmosphere requiring conditions of high temperature and low vacuum above 1000 ° C. In addition, sodium ions and the like have been reported to be involved in the synthesis of metal oxide nanorods [Teshima et al., Cryst. Grow. Des., 2008, 8, pp 465-469] NaCl and NaCO ₃ were used as source materials of sodium. In this case, however, the process must be carried out at temperatures above the melting point (about 1200 ° C) at which they dissolve in order to obtain the flux of the sodium source material.

The 1D nanostructure is a material that can be used as an environmental gas sensor and a photocatalyst environmental purification material using a large surface area of nanomaterials and is expected to have economic ripple effects. Several attempts have been made to synthesize advanced materials that can control shape and composition using biomaterials commonly found in nature such as shells and diatoms. Shape control was performed using a certain size protein synthesized using bacteriophage as a template or by Sarikaya et al., Nat. Mater., 2003, 2, pp 577-585] The diatoms with micropores at high temperature and high pressure of 1000 ° C. or higher were intended to be converted into metal oxide structures in which pores were not destroyed [Sandhage et al., Adv. Mater., 2002, 14, pp 429-433]. However, in the case of bacteriopage, the synthesis amount and conversion yield are low due to the reaction in the organism, and in the case of diatoms, the conversion to a single component metal oxide is difficult.

An object of the present invention is to improve the conventional nanostructures using expensive raw materials, or process is not easy, and also nanostructures such as nanorods, nanowires, nanodisks having a relatively high conversion rate It is intended to provide a method for preparing the.

To solve the above problems,

The present invention uses a metal oxide as a precursor, but provides a method for producing a metal oxide 1D nanostructure, characterized in that the metal oxide is supported and heat treated inside the bivalve shell.

In another aspect, the present invention provides a metal oxide 1D nanostructure prepared by the above method.

Through the above problem solving means,

The present invention provides a nanostructure having a high conversion yield, mass production is possible, is easy to separate and recover the metal oxide 1D nanostructure, environmentally friendly and low process cost as a source technology of the 1D nanostructure material industry Can be utilized.

The present invention provides a method for producing a metal oxide 1D (one-dimensional) nanostructure using a metal oxide (precursor) as a precursor, supporting the metal oxide inside the bivalve shell and heat treatment. do.

In the present invention, the heat treatment may carry a metal oxide in the bivalve shell and heat treatment at 500-900 ° C. for 4 to 13 hours.

In the present invention, the metal oxide is a group consisting of tantalum (Ta), chromium (Cr), manganese (Mn), zirconium (Zr), arsenic (As), titania (Ti), tungsten (W) and molybdenum (Mo). It may include any one metal selected from, but is not limited thereto.

The present invention provides a metal oxide 1D nanostructure prepared by the above method.

In the present invention, the metal oxide 1D nanostructure may be any one selected from the group consisting of nanorods, nanowires, and nanodisks.

Hereinafter, the metal oxide 1D nanostructure of the present invention and a manufacturing method thereof will be described in detail.

The present invention provides a method for producing a metal oxide 1D nanostructure for producing a nanostructure that is utilized in various fields in a simpler and more economical way. Economical and eco-friendly materials use bivalve shells, and nanostructures can be obtained using metal oxides as precursors. More specifically, 1D nanostructure can be obtained by reacting metal oxide with a certain temperature using sodium present in the bivalve shell.

Specific manufacturing method according to the present invention is easy to obtain from the sea, the step of preparing a bivalve shell shell which is used as food waste remaining; and the step of supporting the metal oxides of titania, tungsten, molybdenum, etc. in the shell; And heat-treating the shell on which the metal oxide is supported in an electric furnace.

In the above specific manufacturing method, the nano-structure can be prepared by supporting a relatively inexpensive metal oxide inside the shell such as oysters and put in an electric furnace for 4 to 13 hours heat treatment at 500 ~ 900 ℃. More preferably, the nanostructure may be prepared at a conversion rate of 95 wt.% Or more by heat treatment at 600 to 800 ° C. for 4 to 8 hours. The heat treatment temperature is lower than that of the conventionally known method for manufacturing nanostructures, and thus, it is possible to reduce the process cost and to quickly commercialize the product.

In addition, in the above specific manufacturing method, the bivalve shell shell may be used, such as oysters, mixed, ramie clam or silk clam.

In the above specific manufacturing method, the metal oxide may be tantalum (Ta), chromium (Cr), manganese (Mn), zirconium (Zr), arsenic (As), titania (Ti), tungsten (W) or molybdenum (Mo). ) May be used, but is not limited thereto.

The present invention provides a metal oxide 1D nanostructure using the above manufacturing method, in particular, the metal oxide 1D nanostructure may be any one selected from the group consisting of nanorods, nanowires and nanodisks. Preferably, the metal oxide 1D nanostructure is any one selected from the group consisting of Na ₂ Ti ₆ O ₁₃ , which is a nanorod including sodium component, Na ₂ W ₄ O ₁₃ , which is a nanowire, and Na ₂ Mo ₄ O ₁₃ , which is a nanodisk. It can be one. In the case of nanorods, titania (Ti), nanowires tungsten (W), and nanodisks may use molybdenum (Mo) as metal oxides, but other metal oxides mentioned above may also be used.

The present invention will be described in more detail with reference to the following examples. However, the following examples do not limit the scope of the present invention.

The bivalve shells commonly used in Examples in the present invention are oysters, mussels, ramie shells, and non-shell shells (see FIG. 1).

Table 1 Composition of inorganic elements in bivalve shells (unit: ppm)

Element Kinds Oyster mussel Clam Silk shell Ca 91271.42 92677.09 93253.01 99145.98 K 1080.70 2535.42 1413.35 916.09 Mg 1945.63 1616.84 99.95 191.71 Mn 44.82 17.20 52.69 2.33 Na 7303.88 3713.89 5727.53 6693.15 Cl ^- 20-30

(As shown in Table 1, shells except mussels contained approximately 5,700 ppm or more of sodium, while chlorine ions contained dozens of ppm.)

Most of these bivalve shells consist of calcium carbonate (CaCO ₃ ), which synthesizes calcium carbonate using carbon dioxide (CO ₂ ) and calcium (Ca) ions present in seawater. In the process of synthesizing these shells, sodium and magnesium ions (Na ⁺ and Mg ^{2 +} ), etc., present in the seawater are partially contained in the shell. In particular, the sodium ions present in the shell are known to be in weak bonds with carbonate ions or in ionic form between layers.

In the present invention, these sodium components present in the shell were intended to be used for the synthesis of nanorods (Na ₂ Ti ₆ O ₁₃ ), nanowires (Na ₂ W ₄ O ₁₃ ), and nanodisks (Na ₂ Mo ₄ O ₁₃ ). The conventional method of using a sodium source material as a flux was to synthesize 1D nanostructures at a high temperature of 1200 ° C. by adding an excess of sodium reagent and sodium carbonate. The weakly bound sodium ions present in the present invention were determined to be able to expect the sodium effect at a relatively low temperature. In addition, the present invention does not need a separation process with the sodium source material after the synthesis of the metal oxide 1D nanostructure, and has the advantage of reducing the process cost.

In particular, the technology of synthesizing nanorods, nanowires, and nanodisks using shells, which are waste resources, has not been studied in Korea and Western countries. It can be evaluated by nanomaterial synthesis technology.

≪ Example 1 >

A nanorod Na ₂ Ti ₆ O ₁₃ , one form of metal oxide 1D nanostructure, was prepared.

The precursor of the metal oxide used in the experiment was P25 of Degussa based on titania (TiO ₂ ). The precursor was placed in an electric furnace while being supported inside the shell of the oyster (see Fig. 1B), and heated for 6 hours at a temperature of 700 ° C.

For the analysis of the shape of the synthesized nanostructures, a scanning electron microscope (PHILIPS XL30SFEG, HITACHI S4800) was analyzed under an acceleration voltage of 10-15 kV, and a transmission electron microscope (Techani F30 S-Twin, FEI) was analyzed at an acceleration voltage of 300 kV. In order to confirm the crystal phase, it was measured under conditions of 40 kV and 45 mA using an X-t diffraction analyzer (D / MAX-IIIC, RIGAKU).

As shown in Figure 2a-b it was confirmed that Na ₂ Ti ₆ O ₁₃ which is a smooth surface and a rounded end portion, the size of the nanorods of about 280nm in diameter, 2nm in length or more. In addition, as can be seen in Figure 2b the TiO ₂ precursor (P25) used in the experiment was found to be converted to the nano rod of the aspect ratio of 50 or more industrial value.

As shown in FIGS. 3A-B, the direction of the crystal plane can be determined by using the transmission electron microscope image (FIG. 3A) and the diffraction pattern (FIG. 3B). The nanorod (Na ₂ Ti ₆ O ₁₃ ) is used to [ 010] was grown in the direction. This means that crystal growth was promoted in the [110] direction, which is relatively excellent in thermal stability, in the crystal plane of Na ₂ Ti ₆ O ₁₃ , which could be confirmed using an electron transmission microscope.

As shown in FIG. 4A, in the 2 Theta value of 27.3 degrees (○ in FIG. 4), the main peak of the rutile phase, which is one of the crystal phases of TiO ₂ , which is a constituent of P25 used as a precursor of early titania, was found, but the amount was 2 It was confirmed that 97 wt.% Or more was synthesized as Na ₂ Ti ₆ O ₁₃ as ˜3 wt.%. In other words, the experimental results show that the conversion rate from the metal oxide precursor to the nanofilm compatibility is very high.

<Example 2>

Another form of metal oxide 1D nanostructure, nanowire Na ₂ W ₄ O _13, was prepared.

Tungsten (WO ₃ is Tungsten (VI) oxide powder (WO ₃ , ˜20um, 99 +% pure, Aldrich)) was used as a precursor of the metal oxide used in the experiment. The precursor was placed in an electric furnace while being supported inside the shell of the oyster (see Fig. 1B), and heated for 6 hours at a temperature of 700 ° C.

For the analysis of the shape of the synthesized nanostructures, a scanning electron microscope (PHILIPS XL30SFEG, HITACHI S4800) was analyzed under an acceleration voltage of 10-15 kV, and a transmission electron microscope (Techani F30 S-Twin, FEI) was analyzed at an acceleration voltage of 300 kV. In order to confirm the crystal phase, it was measured under conditions of 40 kV and 45 mA using an X-t diffraction analyzer (D / MAX-IIIC, RIGAKU).

As shown in Figure 2c-d it was confirmed that Na ₂ W ₄ O ₁₃ of several millimeters of nanowires. Also, as can be seen in FIG. 2D, the WO ₃ precursor used in the experiment was found to have been converted to nanowires having an aspect ratio of 100 or more industrially useful.

As shown in FIGS. 3c-d, the direction of the crystal plane can be determined by using the transmission electron microscope image (FIG. 3c) and the diffraction pattern (FIG. 3d). Using this, nanowires (Na ₂ W ₄ O ₁₃ ) are [ 001] was grown in the direction. This confirms that the growth of crystals similar to the 100 plane represented by the main crystal growth plane of Na ₂ W ₄ O ₁₃ was promoted.

In FIG. 4B, only the characteristic peaks of Na ₂ W ₄ O ₁₃ are identified, including the main characteristic peaks (948 cm ⁻¹ and 776 cm ⁻¹ ) of the nanowires (Na ₂ W ₄ O ₁₃ ) synthesized using shells. Could. Thus, the synthesis of single phase nanowires (Na ₂ W ₄ O ₁₃ ) could be confirmed. In other words, the experimental results show that the conversion from precursor to nanomembrane is very high.

WO ₃ is currently known to be a suitable material for use in gas sensors such as NOx [Kudo and Kato, Chemistry Letter, 1997, 26, pp421-426]. In order to increase the adsorption area of gas, studies are being conducted to apply porous WO ₃ in the form of a membrane or to synthesize a wire structure.In terms of sensitivity and recovery time, one or more semiconducting nanowires are used for gas detection ( It is reported to be much more efficient for gas sensing.

In the case of the nanowire Na ₂ W ₄ O ₁₃ synthesized through the present invention or the nanorod Na ₂ Ti ₆ O ₁₃ having excellent aspect ratio, it is considered that the crystal surface has a curved micro-twin structure (see FIG. 3D). The increased surface area could be used as a more efficient gas sensor.

The present invention 1D nanostructure and its manufacturing method may be a novel invention useful in the photocatalyst production and related industries, dye-sensitized solar cell precursor production and related industries, as well as industrial applications that can be applied to the plastic, paper filter production industry.

Figure 1 shows the different types of bivalve shells used in the experiment (i: oysters, ii: mussels, iii: clams, iv: clams), (a) the outside of the shells, (b) shells It shows the inside of the.

2 shows metal oxide 1D nanostructures containing sodium synthesized using a shell, wherein (a, b) is Na ₂ Ti ₆ O ₁₃ , which is a nanorod, and (c, d) is Na ₂ W, which is a nanowire. ₄ O ₁₃ , (e, f) represents Na ₂ Mo ₄ O ₁₃ as a nanodisk.

FIG. 3 shows bright images and diffraction patterns of Na ₂ Ti ₆ O ₁₃ (a, b) as nanorods and Na ₂ W ₄ O ₁₃ (c, d) as nanowires.

4 shows XRD analysis of Na ₂ Ti ₆ O _{13 as} a nanorod (a) (○: shows rutile as one of the crystal phases of TiO ₂ ) and Raman of Na ₂ W ₄ O _{13 as} a nanowire. Analysis result (b) is shown.

Claims (5)

A method of manufacturing a metal oxide 1D (one-dimensional) nanostructure, wherein the metal oxide is used as a precursor, but the metal oxide is supported and heat treated in the bivalve shell. The method of claim 1, wherein the heat treatment is performed by supporting a metal oxide in the bivalve shell and performing heat treatment at 500-900 ° C. for 4 to 13 hours. The method of claim 1, wherein the metal oxide is tantalum (Ta), chromium (Cr), manganese (Mn), zirconium (Zr), arsenic (As), titania (Ti), tungsten (W) and molybdenum (Mo). Method for producing a metal oxide 1D nanostructure, characterized in that it comprises any one metal selected from the group consisting of. Metal oxide 1D nanostructure prepared by the method of any one of claims 1 to 3. The metal oxide 1D nanostructure of claim 4, wherein the metal oxide 1D nanostructure is any one selected from the group consisting of nanorods, nanowires, and nanodisks.

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