JP2007007745A - Method for manufacturing metal nanostructure and metal nanostructure manufactured by the manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a metal nanostructure in a rod form, tube form or the like having no defect or variation in size, and to provide a metal nanostructure manufactured by the method. <P>SOLUTION: The method for manufacturing a metal nanostructure comprises steps of supplying a solution phase containing a metal precursor through one side of a porous film and supplying a solution phase containing an oxidation-reduction reagent of the metal precursor through the other side to pores 3aa, 3ab, 3ac to 3ba, 3bb, 3bc to precipitate a metal on the inner wall of each pore by the oxidation reduction in each pore, and eliminating the solution phase when each metal reaches a predetermined thickness to terminate the oxidation reduction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention manufactures metal nanostructures useful in a wide range of fields such as sensors for biochemical analysis and microanalysis, catalysts for polymer synthesis and catalytic reactions, materials for optoelectronics, energy conversion and storage, and electrolyte membranes. The present invention relates to a method and a metal nanostructure manufactured by the manufacturing method.

  Various techniques have been developed for the formation of metal nanostructures, such as synthesis using chemical oxidation / reduction reactions in solution systems or synthesis using photooxidation / photoreduction. The technology for forming metal nanostructures in a solution system enables mass production of inexpensive and simple metal nanostructures, as represented by metal nanoparticle.

  However, with the conventional solution-based metal nanostructure formation technology, the size of the metal nanostructure can be controlled to some extent, but the generally obtained structure is spherical, rod-shaped, ribbon-shaped, wire-shaped. Alternatively, it is difficult to form a metal nanostructure having a tube shape (see, for example, Non-Patent Document 1 and Patent Document 1).

  Under such circumstances, mesoporous silica, which is an aggregate of silica nanochannels formed using a surfactant as a template, has a uniform channel diameter (see, for example, Non-Patent Documents 2 and 3), and thus silica nanochannels are used as templates. Thus, studies have been made on the technology for forming the metal nanostructures or semiconductor nanostructures of the above-mentioned versatile forms (for example, see Non-Patent Documents 4, 5, and 6).

  In these methods using mesoporous silica as a template, generally, metal ions or metal complexes (hereinafter referred to as metal nanostructure precursors) that become precursors of metal nanostructures are introduced into silica nanochannels, and then calcined or oxidized / reduced. Metal nanostructures are formed using

  In the creation of a metal nanostructure using such a conventional silica nanochannel aggregate, the nanostructure to be formed is a metal to perform a nanostructure formation reaction after introducing a metal nanostructure precursor into the silica nanochannel. Depending on the amount of nanostructure precursor introduced, the resulting nanostructures had variations in defects and sizes.

This problem is that the silica nanochannel aggregate is in powder form, the orientation of each nanochannel is random, and the entrance / exit is not secured stably. This is because it is impossible to introduce it.
JP-A-2005-97718 MA Hayat ed. "Colloidal Gold: Principles, Methods, and Applications", Academic Press, San Diego, 1989. Hong Yang et al., Nature, Vol. 379, pp. 703-705 (1996) Yun Feng et al., Nature, Vol. 389, pp. 364-368 (1997) Haifeng Yang et al., Journal of Materials Chemistry, Vol. 15, pp1217-1321 (2005) KS Napolsky et al., Materials Science and Engineering C, Vol. 23, pp. 151-154 (2003) Yi Meng Wang et al., Advanced Materials, Vol. 17, pp. 323-327 (2005)

  As described above, the conventional technology has a problem in that the metal nanostructures such as rods, ribbons, wires, and tubes have defects and variations in size.

  The present invention solves these problems and provides a method for producing a rod-like, ribbon-like, or tube-like metal nanostructure having no defect or size variation, and a metal nanostructure produced by the method. The purpose is that.

  According to the present invention, a solution phase containing a metal precursor is supplied to each pore from one side of the porous membrane, and a solution phase containing an oxidation / reduction reagent for the metal precursor is supplied to each pore from the other side of the porous membrane. And a process for depositing a metal body on the inner wall of each hole by oxidation / reduction reaction in each hole is obtained.

The present invention also provides a method for producing a metal nanostructure, wherein the porous film is a metal oxide film having pores formed by anodic oxidation of a metal film.
Furthermore, the present invention provides a method for producing a metal nanostructure, wherein the porous film is a metal oxide film having silica nanochannels in the pores formed by anodic oxidation of a metal film.

Further, the present invention includes a step of forming a thin film on one surface of the porous film and connecting one end of the deposited metal body of each hole by the thin film after the step of depositing the metal body. A method for producing a nanostructure is provided.
Furthermore, the present invention provides a nano metal structure manufactured by the manufacturing method.

  According to the present invention, since all the holes of the porous film have a length that follows the film thickness, are supported at a fixed position, and both ends of each hole are stably opened, the solution phase containing the metal precursor and A solution phase containing a metal precursor oxidation / reduction reagent is stably supplied to all the pores. Therefore, the oxidation / reduction reaction in all the holes proceeds continuously and uniformly, and the metal body deposited on the inner wall of each hole has no defect and has a uniform size and shape.

For example, when a metal precursor such as platinum chloride, nickel chloride, or chloroplatinic acid is used as the metal precursor solution, a metal nanostructure that follows the hole shape such as gold, nickel, platinum rods, ribbons, or tubes It is possible to form a body.
Further, when the porous film is a metal oxide film having pores formed by anodic oxidation of a metal film, the film thickness is set to several nm to several hundred μm, and the film is oriented perpendicularly to the film surface, and the length follows it. A pore having a diameter of 10 nm to several hundreds nm is arbitrarily obtained. As the metal oxide film, an anodized alumina film is preferable.

Further, if the porous film is formed by forming silica nanochannels in pores formed by anodic oxidation of a metal film, the porous film is oriented perpendicularly to the metal oxide film surface, the inner diameter is narrower to several to 40 nm, and the length is approximately Many desired silica pores that follow the thickness of the metal oxide film can be obtained. Accordingly, a metal nanostructure having a uniform size and shape can be obtained using these pores as templates.
In addition, after the step of depositing the metal body, a thin film is formed on one surface of the porous film, and when one end of the deposited metal body of each hole is connected by the thin film, an array of metal bodies is a sword-like metal planted on the thin film surface. Nanostructures are obtained. The thin film is preferably a metal or carbon thin film.

  Furthermore, since the metal nanostructure manufactured by the manufacturing method has a rod shape, a ribbon shape, or a tube shape with no variation in size and size, a high-quality and high-performance sensor can be realized. It can also be used in a wide range of high-quality, high-performance catalysts, optoelectronics and other materials or electrolyte membranes.

If the tubular metal nanostructure is held in a porous membrane, it is effective as a catalyst, an electrolyte membrane, etc. because it has a large contact surface area when used as a partition wall for a solution phase.
A sword-like metal nanostructure in which an array of metal bodies is implanted on a thin film surface is well dispersed in a solution and has a large contact surface area.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory diagram of a porous film used in the method for producing a metal nanostructure according to an embodiment of the present invention. The porous film 1 has a circular shape as shown in FIG. 1 and is obtained by anodic oxidation. Silica nanochannels are formed in the pores 2a, 2b, 2c, or 2n of the alumina film 2 thus obtained.

The alumina film 2 is generally commercially available, and for example, a film having a diameter Φ1 of 2 cm to 4 cm, a film thickness t1 of 60 μm, and a pore diameter Φ2 of several tens to several hundreds of nm is used.
Inside the pores 2a, 2b, 2c, or 2n of the alumina film 2, silica bodies 3a, 3b, 3c, or 3n are formed inside the pores 2a, 2b, 2c, or 2n of the porous film 1 shown in FIG. Silica nanochannels 3aa, 3ab, 3ac or silica nanochannels 3ba, 3bb, 3bc, etc., having an inner diameter Φ3 of 2 nm to 40 nm and a length t2 slightly shorter than the film thickness t1 of the alumina film 2 are arranged.

  The silica nanochannels 3aa, 3ab, 3ac, silica nanochannels 3ba, 3bb, 3bc, etc. of the pores 2a, 2b, 2c, or 2n of the alumina film 2 are the nanochannels that the present inventors have developed so far. It was formed using a method of forming a film in which aggregates are integrated (Non-patent Document 7, Patent Document 2).

  For example, the nanochannels that form are cetyltrimethylammonium bromide (CTAB), a surfactant, and a silica source. A solution containing tetraethoxysilane (TEOS) was introduced into the pores of the anodized alumina and dried. The nanochannel bodies are arranged and accumulated perpendicular to the surface of the alumina film 2.

In such a nanochannel integrated film in which the nanochannel bodies are arranged and integrated perpendicularly to the surface of the alumina film 2, different substances can be introduced into the nanochannel body from both sides of the nanochannel integrated film.
Japanese Patent Application Laid-Open No. 2004-261779 A kira Yamaguchi et al., Nature Materials, Vol. 3, pp337-341 (2004) Next, a manufacturing apparatus used in the method for manufacturing a metal nanostructure according to an embodiment of the present invention will be described. FIG. 2 is a perspective view of a main part of a manufacturing apparatus using the porous membrane 1. As shown in FIG. 3, the manufacturing apparatus has a U-shaped configuration in which a glass tube 4 and a glass tube 5 are connected to each other at the center. The porous film 1 is sandwiched and fixed between the glass tube 4 and the glass tube 5 at the boundary of the connecting portion.

  In addition, regarding the shape of the glass tube, a U-shaped configuration is used here, but there is no restriction on the shape of the glass tube, and any shape may be used. As shown in FIG. 4, a solution phase 6 containing a metal precursor is introduced into one glass tube 4 sandwiching the porous membrane 1, and an oxidation / reduction reagent for the metal precursor is introduced into the other glass tube 5. A containing solution phase 7 is introduced.

  For example, chloroauric acid can be used for the metal precursor of the solution phase 6, and aniline can be used for the oxidizing / reducing agent of the metal precursor of the solution phase 7, for example. In addition, heavy metal ions such as platinum, nickel and iron or complexes thereof can be used for the metal precursor of the solution phase 6, and pyridine, imidazole can be used as the oxidizing / reducing agent for the metal precursor of the solution phase 7. It is possible to use an organic reagent such as citric acid, or an inorganic reagent such as hydrogen or sodium boron or sodium sulfite, which is usually used as an oxidizing / reducing agent for a metal precursor.

  4 to 8 are main process diagrams showing a method for manufacturing a metal nanostructure using such a manufacturing apparatus. As shown in FIG. 4, the solution phase 6 and the solution phase 7 pass through the porous film 1. The silica nanochannels 3aa, 3ab, 3ac or the silica nanochannels 3ba, 3bb, 3bc of the porous membrane 1 have a solution phase 6 as shown in FIG. Phase 7 is fed simultaneously along arrow b.

  As a result, for example, as shown in FIG. 6, the oxidation / reduction reaction of the metal precursor proceeds in the silica nanochannel 3aa, and the metal body 8aa is deposited on the inner wall of the silica nanochannel 3aa. When chloroauric acid is used for the metal precursor of the solution phase 6 and aniline is used for the oxidizing / reducing agent of the metal precursor of the solution phase 7, gold is deposited.

  This oxidation / reduction reaction of the metal precursor proceeds simultaneously in all silica nanochannels 3aa, 3ab, 3ac or silica nanochannels 3ba, 3bb, 3bc. Therefore, although not shown, metal bodies 8ab, 8ac, 8ba, 8bb, and 8bc are simultaneously deposited on the inner walls of the other silica nanochannels 3ab and 3ac or the silica nanochannels 3ba, 3bb, and 3bc.

  When the thickness of each metal body 8aa, 8ab, 8ac, 8ba, 8bb, 8bc reaches a predetermined thickness t4, the solution phase 6 and the solution phase 7 are removed from the glass tube 4 and the glass tube 5, and the metal precursor is removed. End the body's oxidation / reduction reactions. Thereafter, the porous film 1 on which the metal bodies 8aa, 8ab, 8ac, 8ba, 8bb, and 8bc are deposited is separated from the glass tube 4 and the glass tube 5 and washed appropriately. The reaction time is about several minutes to several hours at room temperature and normal pressure, and depends on the types of the solution phase 6 and the solution phase 7.

  At this stage, as shown in FIG. 5, the metal bodies 8aa, 8ab, 8ac, 8ba, 8bb, 8bc, etc., each of which is a metal nanostructure, are converted into silica nanochannels 3aa, 3ab, 3ac or silica nanochannels of the porous film 1. The thing stuck to the inner walls of 3ba, 3bb, 3bc, etc. is obtained. The shape of the metal bodies 8aa, 8ab, 8ac, 8ba, 8bb, 8bc is a tube shape whose outer diameter follows the diameter of silica nanochannels 3aa, 3ab, 3ac or silica nanochannels 3ba, 3bb, 3bc, and has a film thickness of t4. The length t3 is slightly shorter than the length t2 of the silica nanochannels 3aa, 3ab, 3ac or the silica nanochannels 3ba, 3bb, 3bc.

  If the reaction time is made sufficiently long, the hollow portions of the metal bodies 8aa, 8ab, 8ac, 8ba, 8bb, 8bc, etc. are filled with the metal bodies and become rod-shaped. Such metal bodies 8aa, 8ab, 8ac, 8ba, 8bb, and 8bc are tube-shaped or rod-shaped metal nanostructures having no defect and uniform sizes.

  Here, when the alumina body 2 of the porous film 1 and silica bodies 3a, 3b, 3c, or 3n such as silica nanochannels 3aa, 3ab, 3ac or silica nanochannels 3ba, 3bb, 3bc are dissolved, the metal bodies 8aa, 8ab, Only 8ac, 8ba, 8bb, 8bc, etc. can be taken out. As an aqueous solution that dissolves the alumina body 2 and silica bodies 3a, 3b, 3c, or 3n such as silica nanochannels 3aa, 3ab, 3ac or silica nanochannels 3ba, 3bb, 3bc, an aqueous NaOH solution, an aqueous HF solution, or the like may be used. it can.

  Further, the metal bodies 8aa, 8ab, 8ac, 8ba, 8bb, 8bc, etc., which are metal nanostructures, are formed on the inner walls of the silica nanochannels 3aa, 3ab, 3ac or silica nanochannels 3ba, 3bb, 3bc, etc. By forming a metal or carbon thin film on one surface of the stuck state, a sword-like metal nanostructure having an array of metal bodies implanted on the thin film surface can be obtained. FIGS. 8-12 is principal part process drawing which shows the manufacturing process of such a metal nanostructure.

  First, as shown in FIG. 8, a thin film 9 is formed on the lower surface of the porous film 1 to a predetermined thickness by sputtering, CVD, or the like, for example. As a result, as shown in FIG. 9, alumina film 2 of porous film 1, silica nanochannels 3aa, 3ab, 3ac or silica nanochannels 3ba, 3bb, 3bc and metal bodies 8aa, 8ab, 8ac, 8ba, 8bb, 8bc, etc. In the state where the lower end of is connected to the thin film 9.

  Thereafter, when the alumina body 2 of the porous film 1 and the silica bodies 3a, 3b, 3c, or 3n such as silica nanochannels 3aa, 3ab, 3ac or silica nanochannels 3ba, 3bb, 3bc are dissolved, As shown in FIG. 11 as a whole perspective view, an arrayed metal nanostructure in which metal bodies 8aa, 8ab, 8ac, 8ba, 8bb, 8bc and the like are vertically connected to the thin film 9 can be taken out.

  As the aqueous solution for dissolving the silica film 3a, 3b, 3c, or 3n such as the alumina film 2 and the silica nanochannels 3aa, 3ab, 3ac or the silica nanochannels 3ba, 3bb, 3bc, as described above, NaOH aqueous solution, HF aqueous solution Etc. can be used. As a material of the thin film 9, gold, platinum, nickel or the like can be used in addition to carbon.

  In the method of manufacturing a metal nanostructure according to the above-described embodiment, the metal nanostructure has been described as having a tube shape or a rod shape. In addition to this, the pore shape of the porous film is changed to a slit or other shape. By doing so, metal nanostructures of ribbon shape or other various shapes can be obtained.

Next, examples of forming the gold nanostructure will be described.
The alumina film 2 to be used is a commercially available one having a diameter of 2 to 4 cm, a film thickness of 60 μm, and a pore diameter of 100 to 200 nm. The pores 2a, 2b, 2c, or 2n of the alumina film 2 have silica nanochannels 3aa, 3ab, 3ac, or silica nanochannels having an inner diameter of 3.4 nm and a length of 5 mm that is shorter than the thickness of the alumina film 2. Tunnels 3ba, 3bb and 3bc were formed.

  The reduction reaction was carried out using chloroauric acid (2 wt%) as the metal precursor of solution phase 6 and aniline as the reducing agent of solution phase 7. The reaction time was several minutes to several hours, and after the reaction, a tubular gold nanostructure was formed on the inner walls of silica nanochannels 3aa, 3ab, 3ac or silica nanochannels 3ba, 3bb, 3b.

  Next, this is immersed in a 2 mol / l NaOH aqueous solution, and all of the alumina film 2 and silica nanochannels 3aa, 3ab, 3ac or silica nanochannels 3ba, 3bb, 3bc, and the silica bodies 3a, 3b, 3c, or 3n. Dissolved. Thereafter, the residue was washed and observed with a transmission electron microscope (TEM). As a result, formation of a tubular gold nanostructure was confirmed as shown in FIG. FIG. 13 is an enlarged view of the tip portion of the gold nanostructure aggregate shown in FIG.

  The diameter of the tubular gold nanostructure is approximately 3 nm, which is almost the same as the diameter of the nanochannel that is the template. The length of the tube-shaped gold nanostructure is slightly shorter than the length of the nanochannel that is the template, which is about 1 mm, but it can be seen that an almost uniform tube-shaped gold nanostructure is formed. . Further, it was confirmed by EDS measurement that the composition of the structure of FIG. 12 was composed of gold. From the above results, it was confirmed that it was possible to easily create tubular gold nanostructures with uniform size using nanochannels as templates.

  Similarly, the reduction reaction was carried out using chloroauric acid (1 wt%) as the metal precursor of solution phase 6 and aniline as the reducing agent of solution phase 7. The reaction time was about several minutes, and after the reaction, ribbon-like gold nanostructures were formed on the inner walls of silica nanochannels 3aa, 3ab, 3ac or silica nanochannels 3ba, 3bb, 3b.

  Next, this is immersed in a 2 mol / l NaOH aqueous solution, and all of the alumina film 2 and silica nanochannels 3aa, 3ab, 3ac or silica nanochannels 3ba, 3bb, 3bc, and the silica bodies 3a, 3b, 3c, or 3n. Dissolved.

  Thereafter, the residue was washed and observed with a transmission electron microscope (TEM), a scanning electron microscope (SEM), and a dispersive X-ray elemental analyzer (EDS) attached to the SEM. Formation was confirmed. Gold nanostructures formed inside silica nanochannels aggregate in the process of dissolving silica film 3a, 3b, 3c, or 3n of alumina film 2 and silica nanochannels 3aa, 3ab, 3ac or silica nanochannels 3ba, 3bb, 3bc. Then, it was observed as a gold nanostructure aggregate shown in the SEM image of FIG.

  Further, from the observation diagram by the dispersive X-ray elemental analyzer (EDS) shown in FIG. 15, it was confirmed that the composition of the structure of FIG. 14 was composed of gold. Furthermore, when the microstructure of the gold nanostructure aggregate was evaluated by TEM observation, it was found that the ribbon-like gold nanostructure was aggregated as shown in FIG.

The width of the ribbon-like gold nanostructure is about 10 nm, and its length is several mm. This is almost the same as the circumference (approximately 11 nm) and length (5 mm) of the nanochannel that is the template. From the above results, we confirmed that ribbon-like gold nanostructures can be created using nanochannels as templates.
Thus, it was confirmed that by controlling the reaction conditions, metal nanostructures of various shapes such as tubes, ribbons, etc. can be obtained.

  The method for producing a metal nanostructure according to the present invention is capable of obtaining tube-shaped, rod-shaped or other metal nanostructures having no defect and having a uniform size. In order to provide basic technology for device development using electrical / magnetic properties and optical properties, as a sensor for biochemical analysis and trace component analysis using metal nanostructures, which are expected in the future, and even polymers It can be widely used in a wide range of fields such as synthesis, catalytic reaction, optoelectronics, energy conversion and storage, and electrolyte membrane.

It is explanatory drawing of the porous film concerning the manufacturing method of the metal nanostructure of embodiment of this invention. It is explanatory drawing of the porous film concerning the manufacturing method of the metal nanostructure of embodiment of this invention. It is a principal part perspective view of the manufacturing apparatus concerning the manufacturing method of the metal nanostructure of embodiment of this invention. It is a principal part perspective view of the manufacturing apparatus concerning the manufacturing method of the metal nanostructure of embodiment of this invention. It is principal part process drawing which shows the manufacturing method of the metal nanostructure of embodiment of this invention. It is principal part process drawing which shows the manufacturing method of the metal nanostructure of embodiment of this invention. It is principal part process drawing which shows the manufacturing method of the metal nanostructure of embodiment of this invention. It is another principal part process drawing which shows the manufacturing method of the metal nanostructure of embodiment of this invention. It is another principal part process drawing which shows the manufacturing method of the metal nanostructure of embodiment of this invention. It is another principal part process drawing which shows the manufacturing method of the metal nanostructure of embodiment of this invention. It is another principal part process drawing which shows the manufacturing method of the metal nanostructure of embodiment of this invention. It is the observation figure which observed the principal part of the metal nanostructure of the Example of this invention with the transmission electron microscope (TEM). It is the observation figure which observed the principal part of the metal nanostructure of the Example of this invention with the transmission electron microscope (TEM). Observation view of main parts of metal nanostructures of other examples of the present invention observed with a transmission electron microscope (TEM), a scanning electron microscope (SEM), and a dispersive X-ray elemental analyzer (EDS) attached to the SEM It is. Observation view of main parts of metal nanostructures of other examples of the present invention observed with a transmission electron microscope (TEM), a scanning electron microscope (SEM), and a dispersive X-ray elemental analyzer (EDS) attached to the SEM It is. Observation view of main parts of metal nanostructures of other examples of the present invention observed with a transmission electron microscope (TEM), a scanning electron microscope (SEM), and a dispersive X-ray elemental analyzer (EDS) attached to the SEM It is.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Porous film 2 Alumina film | membrane 3a, 3b, 3c thru | or 3n Silica body 3aa, 3ab, 3ac thru | or 3bb, 3bb, 3bc Silica nanochannel 4 5, Glass tube 6 Solution phase containing metal precursor 7 Oxidation of metal precursor Solution phase containing reducing agent 8aa, 8ab, 8ac, 8ba, 8bb, 8bc Metal body 9 Thin film

Claims (5)

A solution phase containing a metal precursor is supplied to each hole from one side of the porous film and a solution phase containing an oxidation / reduction reagent for the metal precursor is supplied to each hole from the other side of the porous film. A method for producing a metal nanostructure, comprising a step of depositing a metal body on an inner wall of each hole by an oxidation / reduction reaction in the hole. 2. The method for producing a metal nanostructure according to claim 1, wherein the porous film is a metal oxide film having pores formed by anodic oxidation of a metal film. The method for producing a metal nanostructure according to claim 2, wherein the porous film is a metal oxide film having silica nanochannels in the pores formed by anodization of a metal film. 2. The metal according to claim 1, further comprising a step of forming a thin film on one surface of the porous film and connecting one end of the deposited metal body of each of the holes by the thin film after the step of depositing the metal body. A method for producing a nanostructure. A metal nanostructure produced by the method for producing a nanometal structure according to claim 1.