KR101522071B1 - Method of fabricating bimetallic particles and bimetallic particles fabricated by the method - Google Patents

Abstract

The present invention provides a method for forming a precursor solution, comprising: forming a precursor solution by adding a first metal salt comprising a first metal, a second metal salt comprising a second metal and a non-ionic surfactant to a solvent, Forming a composite metal particle comprising a first metal contained in the first metal salt and a second metal contained in the second metal salt by adding a reducing agent to the solution, There is provided a process for producing composite metal particles which are polyoxyethylene, polyoxyethylene sorbitan monolaurate or polyoxyethylene oleyl ether, and the composite metal particles produced thereby.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a method for producing composite metal particles and a composite metal particle produced by the method.

The present invention relates to a process for producing composite metal particles and to composite metal particles produced thereby.

Nanoparticles are particles with nanoscale particle size. Due to the quantum confinement effect and the large specific surface area, the energy required for electronic transfer varies depending on the size of the material. , Electrical and magnetic properties. Therefore, much attention has been focused on the availability in the catalytic field, the electromagnetics field, the optical field, the medical field, etc. due to this property. Nanoparticles are intermediates of bulk and molecules, and nanoparticles can be synthesized in terms of two approaches: the "top-down" approach and the "bottom-up" approach.

Methods for synthesizing metal nanoparticles include a method of reducing metal ions in a solution in a solution, a method using a gamma ray, an electrochemical method, and the like. However, in the conventional methods, it is difficult to synthesize nanoparticles having a uniform size and shape, It has been difficult to economically mass-produce high-quality nanoparticles for various reasons such as environmental pollution, high cost, and the like.

Korean Patent Laid-Open Publication No. 10-2006-0069491 discloses that metal nanoparticles are formed by mixing a metal complex of an organic metal compound and an amine in an organic solvent, but it is difficult to solve the problems of environmental pollution, A method for producing the composite metal particles which can be produced by the method has not been proposed.

Korean Patent Publication No. 10-2006-0069491

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to provide a method for producing composite metal particles which is free from environmental pollution and can be mass-produced easily at a relatively low cost.

Another problem to be solved by the present invention is to provide a composite metal particle produced by the above production method.

The problems to be solved by the present invention are not limited to the above-mentioned technical problems, and other technical problems which are not mentioned can be clearly understood by those skilled in the art from the following description.

According to another aspect of the present invention, there is provided a method of fabricating a composite metal particle, including: forming a first metal salt including a first metal, a second metal salt including a second metal, ionic surfactant to a solvent to form a precursor solution; Adding a reducing agent to the precursor solution; A first metal included in the first metal salt; And forming a composite metal particle comprising a second metal contained in the second metal salt, wherein the surfactant is selected from the group consisting of polyoxyethylene, polyoxyethylene sorbitan monolaurate or polyoxyethylene sorbitan monolaurate Polyoxyethylene oleyl ether.

According to another embodiment of the present invention, there is provided a composite metal particle according to the present invention.

The details of other embodiments are included in the detailed description and drawings.

According to the present invention, there is provided a process for producing a composite metal particle which is free from environmental pollution and can be easily mass-produced at a relatively low cost, and a composite metal particle produced thereby.

FIG. 1 is a flowchart illustrating a method of manufacturing a composite metal particle according to an embodiment of the present invention. Referring to FIG.
2 is a TEM photograph of composite metal particles produced according to Example 1 of the present invention.
FIG. 3 is a graph showing the results of measurement of mass activity per mass of the composite metal particles prepared in Examples 1 and 2 and Comparative Example 1. FIG.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. The dimensions and relative sizes of the components shown in the figures may be exaggerated for clarity of description.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. In addition, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

Hereinafter, a method for producing metal composite particles according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG.

FIG. 1 is a flow chart showing a method for producing composite metal particles according to an embodiment of the present invention, FIG. 2 is a TEM photograph of composite metal particles produced according to Example 1 of the present invention, and FIG. And graphs showing the results of measurement of the mass activity per mass of the composite metal particles prepared in Examples 1 and 2 and Comparative Example 1. FIG.

First, referring to FIG. 1, a precursor solution is formed by adding a first metal salt, a second metal salt, and a non-ionic surfactant to a solvent (S1010).

In one embodiment of the present invention, the first metal salt is not particularly limited as long as it can ionize the solution to provide a metal ion. The first metal salt, for example, nitrogen oxides (Nitrate, NO ₃ ^-), chloride, halides (Halide), such as (Chloride, Cl ^-), bromide (Bomide, Br ^{- -),} iodide (Iodide, I) , Hydroxides (OH ^- ) or sulfurates (SO ₄ ^- ), but are not limited thereto.

In one embodiment of the present invention, the first metal salt may comprise a first metal. Here, the first metal may be platinum (Pt) or palladium (Pd). Accordingly, the first metal salt may be at least one selected from the group consisting of platinum (Pt) -nitrate, platinum-halide, platinum-hydroxide, platinum- Pd) -nitrate, palladium (Pd) -halide, palladium (Pd) -hydroxide, and palladium (Pd) -sulfate.

In an embodiment of the present invention, the second metal salt is not particularly limited as long as it can ionize the solution to provide a metal ion. This second metal may, for example, nitrogen oxides (Nitrate, NO ₃ ^-), chloride, halides (Halide), such as (Chloride, Cl ^-), bromide (Bomide, Br ^{- -),} iodide (Iodide, I) , Hydroxides (OH ^- ) or sulfurates (SO ₄ ^- ), but are not limited thereto.

In one embodiment of the present invention, the first metal salt may comprise a first metal. Here, the second metal may be at least one selected from the group consisting of nickel (Ni), iron (Fe), cobalt (Co), and copper (Cu) Thus, the second metal salt can be selected from the group consisting of nickel (Ni) -nitrate, nickel-halide, nickel-hydroxide, nickel- Fe-nitrate, iron-halide, iron-hydroxide, iron-sulfate, cobalt-nitrate, Cobalt (Co) - halide, cobalt - hydroxide, cobalt - sulfate, copper - nitrate, copper - halide, , Copper (Cu) -hydroxide, and copper (Cu) -sulfate.

In one embodiment of the present invention, the surfactant may be non-ionic. A nonionic surfactant is preferable because it does not contain a metal component which becomes an impurity. In addition, the nonionic surfactant has an advantage that the hydrophilic lipophilic balance (HLB) can be relatively freely controlled. This makes it possible to control the hydrophilic and lipophilic balance values, such as increasing the hydrophilicity, decreasing the lipophilicity, decreasing the hydrophilicity and increasing the lipophilicity depending on the physical properties of the solvent, and maximizing the utilization of the surfactant.

In one embodiment of the present invention, the surfactant can form a micelle containing a hydrophilic branch in a solvent. The first and second metal salts may be entrapped in the hydrophilic branch of the micelle. Whereby the first metal salt and the second metal salt dissolved in the solvent can be bound in solution. A composite in which the first metal salt and the second metal salt are bonded to each other by a surfactant can be formed. On the other hand, the surface of the composite can also be adsorbed by the surfactant, whereby the composite can be uniformly dispersed in the solution. Thereby, metal complex particles of uniform size can be formed in the solution.

In one embodiment of the present invention, the surfactant may be, for example, polyoxyethylene, polyoxyethylene sorbitan monolaurate or polyoxyethylene oleyl ether . Here, the number of repeating oxyethylene units contained in polyoxyethylene, polyoxyethylene sorbitan monolaurate or polyoxyethylene oleyl ether may be 10 to 25. If the number of repeating oxyethylene is less than 10, the dispersibility of the composite due to the binding of the first metal salt and the second metal salt in the solution becomes weak, so that it is difficult to uniformly disperse the composite, and the possibility of aggregation of the particles is high. On the other hand, if the number of repeating oxyethylene exceeds 25, the dispersion of the complex in the solution can be achieved, but it may not be preferable from an economical point of view.

In one embodiment of the present invention, when water is selected as the solvent, the concentration of the surfactant may be 2 to 10 times the critical micelle concentration (CMC) in water in solution.

In one embodiment of the present invention, the solvent dissolves and disperses the first metal salt, the second metal salt and the surfactant, wherein the solvent can be water or a mixture of water and a C ₁ -C ₆ alcohol, have. Water may be selected as a solvent in view of minimizing environmental contamination that can be caused during formation of the composite metal particles and performing the process at a relatively low cost.

In view of the foregoing, when water is selected as a solvent, the concentration of the surfactant may be 2 to 10 times the critical micelle concentration (CMC) for water. The critical micelle concentration refers to the concentration at which the micelle aggregate is formed without further increasing the electrical conductivity even when the concentration of the water-soluble surfactant increases.

In one embodiment of the present invention, if the concentration of the surfactant is less than two times the critical micelle concentration, the concentration of the surfactant adsorbed on the first metal salt and the second metal salt may be relatively small, The possibility that the second metal salt is adsorbed to each other can be reduced and the amount of the complex composed of the first metal salt and the second metal salt can be relatively reduced. Also, even if the first metal salt and the second metal salt are combined, the bonding force can be weakened, and the formed composite can be relatively easily separated into the first metal salt and the second metal salt. Accordingly, the amount of the composite metal particles to be formed can be reduced as a whole. If the concentration of the surfactant is less than 2 times the critical micelle concentration, the size of the metal composite particles formed may be larger than the nano scale. For example, If used, the efficiency of the catalyst may be lowered.

In one embodiment of the present invention, when the concentration of the surfactant exceeds 10 times the critical micelle concentration, the concentration of the surfactant adsorbed on the first metal salt and the second metal salt becomes relatively large, May be sufficient, but the amount of the complex to be formed may become saturated and the formation of the complex may not be made any longer, which may be undesirable from the viewpoint of economic efficiency of the process.

In one embodiment of the invention, the step of forming the solution may be carried out at ambient temperature, specifically at a temperature in the range of 4 ° C to 35 ° C.

Subsequently, a reducing agent is added to the precursor solution (S1020).

In one embodiment of the present invention, the reducing agent is not particularly limited as long as it is a strong reducing agent having a standard reduction potential of -0.23 V or lower and a reducing power capable of reducing dissolved metal ions to precipitate into metal particles.

Such a reducing agent may be any one or a mixture of two or more selected from the group consisting of NaBH ₄ , NH ₂ NH ₂ , LiAlH ₄ and LiBEt ₃ H, for example.

When a weak reducing agent is used, the reaction rate is low and subsequent heating of the solution is required, which makes it difficult to carry out continuous processing. Thus, there is a problem in mass production, and in particular, when ethylene glycol, which is a kind of weak reducing agent, is used, There is a problem that the productivity in the continuous process is low due to the decrease of the flow rate.

Subsequently, composite metal particles containing a first metal contained in the first metal salt and a second metal contained in the second metal salt are formed (S1030).

In one embodiment of the present invention, the precursor solution comprises a complex of a first metal salt and a second metal salt, wherein the reducing agent includes a reducing agent that reduces the first metal of the first metal salt, Reduce the metal. Thereby, the composite is formed of composite metal particles comprising a first metal and a second metal.

More specifically, for example, when the first metal salt is a platinum-halide containing platinum (Pt) as the first metal, the formula is H ₂ PtCl ₆ . At this time, Pt ^{+ 4} can be reduced to Pt ⁰ by the reducing agent. On the other hand, when the second metal salt is a nickel-halide containing nickel (Ni) as the second metal, the formula is NiCl ₂ . At this time, by reducing Ni ⁺² may be reduced to Ni ^0. Thereby, it can be formed of composite metal particles of Pt-Ni. Such a reduction reaction can occur simultaneously in the first metal salt site and the second metal salt site in the precursor solution.

If in one embodiment of the invention, the first and second metal salt is nitrate (nitrate, NO ₃ ^-), a halide ^{(halide, Cl -, Br -} , I -), hydroxide (hydroxide, OH ^-) or Sulfate (SO ₄ ^- ), which can be reduced to form composite metal particles. Accordingly, a reduction reaction can be performed at a relatively lower temperature than when metal acetylacetonate series or metal carbonyl series precursors are reduced to form composite metal particles. In addition, composite metal particles having the same physical properties as those of the composite metal particles formed by reducing the metal acetylacetonate series or metal carbonyl series precursors can be formed. That is, the composite metal particles can be formed under mild conditions, which is advantageous from the viewpoint of economical processing.

In one embodiment of the present invention, the step of forming the composite metal particles is performed by mixing the reducing agent and the complex of the first metal salt and the second metal salt for a predetermined time, specifically 10 minutes to 120 minutes, specifically 20 minutes to 90 minutes And then reacted to form composite metal particles.

In one embodiment of the present invention, the step of forming the composite metal particles may be performed at room temperature, specifically at a temperature in the range of 4 ° C to 35 ° C.

On the other hand, after the composite metal particles are formed, the solution containing the composite metal particles may be centrifuged to precipitate the composite metal particles contained in the solution. Only the separated composite metal particles are recovered after centrifugation. If necessary, the firing process of the composite metal particles can be additionally performed.

One embodiment of the present invention provides the composite metal particles produced by the above-mentioned production method.

One embodiment of the present invention provides a catalyst comprising the composite metal particles.

When used as a catalyst, the composite metal particles can be used by being supported on a carrier. As such a carrier, a carbon-based material or an inorganic fine particle may be used. The carbon-based material may be carbon black, carbon nanotube (CNT), graphite, graphene, activated carbon, mesoporous carbon, carbon fiber and carbon nano wire. , And carbon blacks such as denka black, ketjen black, and acetylene black may be used. As the inorganic fine particles, any one or two or more selected from the group consisting of alumina, silica, titania and zirconia may be used, but a carbonaceous material may be generally used.

One embodiment of the present invention provides a fuel cell comprising the catalyst.

Hereinafter, the present invention will be described in detail with reference to Examples, Comparative Examples and Experimental Examples. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention is not construed as being limited to the embodiments described below. Embodiments of the invention are provided to more fully describe the present invention to those skilled in the art.

< Example  1>

78 mg of H ₂ PtCl ₆ as a first metal salt, 71 mg of a Ni precursor NiCl ₂ as a second metal salt, and 40 mg of polyoxyethylene having a repeating number of oxyethylene units of 20 as a surfactant were dissolved in 20 ml of water (distilled water) And dissolved to form a precursor solution, which was then allowed to stand for 10 minutes. Subsequently, 5 ml of NaBH ₄ 30 mg / H ₂ O, which is a reducing agent, was added to the precursor solution in a temperature atmosphere of 25 ° C, and the mixture was allowed to stand for 30 minutes. After centrifugation at 10,000 rpm for 10 minutes, the supernatant in the upper layer was discarded, and the remaining precipitate was redispersed in 20 ml of water, followed by further centrifugation to form composite metal particles containing Pt-Ni.

FIG. 2 shows a photograph of the structural analysis of Pt-Ni particles using the TEM for the composite metal particles. Referring to FIG. 2, Pt-Ni particles having a uniform size are formed. That is, according to the embodiment of the present invention, overall uniform metal composite particles are formed under a relatively mild condition while minimizing environmental pollution.

< Example  2>

The composite metal particles containing Pt-Co were formed using the same method as in Example 1 except that 70 mg of CoCl ₂ was used as the second metal salt.

< Manufacturing example  1>

The composite metal particles of Pt-Ni prepared in Example 1 were supported on the carrier of the carbon nanotubes to prepare the catalyst body 1.

< Manufacturing example  2>

The composite metal particles of Pt-Co prepared in Example 2 were supported on the carrier of the carbon nanotubes to prepare the catalyst body 2.

< Comparative Example  1>

A commercially available 45 wt% platinum-carbon supported (Pt / C) catalyst was purchased and designated as catalyst 3.

< Experimental Example  1>

Oxygen gas was bubbled into the sulfuric acid solution at a concentration of 0.5 M for 2 hours to prepare a sulfuric acid solution saturated with oxygen. The prepared catalyst bodies 1 and 2 and the catalyst body 3 of Comparative Example 1 were added to the sulfuric acid solution . In addition, a platinum mesh was placed as a counter electrode into the sulfuric acid solution, and a voltage was applied to evaluate the oxygen reduction reaction. The results are shown in Fig.

As shown in FIG. 3, the mass activity of the catalyst 1 (PtNi / C) was about 6.5 (A / g Pt) and the activity of the catalyst 2 (PtCo / C) ) Was approximately 6.0 (A / g Pt). On the other hand, the mass activity of catalyst 3 (Pt / C) was approximately 1.5 (A / g Pt). As can be seen from the above results, it can be seen that the composite metal particles prepared according to the embodiment of the present invention have excellent oxygen reducing power.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It is to be understood that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (17)

Adding a first metal salt comprising a first metal, a second metal salt comprising a second metal, and a non-ionic surfactant to a solvent to form a precursor solution;
Adding a reducing agent to the precursor solution; And
Forming composite metal particles comprising a first metal contained in the first metal salt and a second metal included in the second metal salt,
The surfactant may be polyoxyethylene, polyoxyethylene sorbitan monolaurate or polyoxyethylene oleyl ether, and the polyoxyethylene, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monolaurate, The number of repeating units of oxyethylene units contained in the polyoxyethylene oleyl ether or the polyoxyethylene oleyl ether is 10 to 25,
The solvent is water,
Wherein the concentration of the surfactant is 2 to 10 times the critical micelle concentration (CMC) for the water in the solution. delete The method according to claim 1,
Wherein the first metal is platinum (Pt) or palladium (Pd). The method according to claim 1,
The first metal salt may be at least one selected from the group consisting of platinum (Pt) -nitrate, platinum-halide, platinum-hydroxide, platinum- Wherein the metal complex is any one selected from the group consisting of nitrate, palladium (Pd) -halide, palladium (Pd) -hydroxide and palladium (Pd) -sulfate. &Lt; / RTI &gt; The method according to claim 1,
Wherein the second metal is any one selected from the group consisting of Ni, Fe, Co, and Cu. The method according to claim 1,
Wherein the second metal salt is selected from the group consisting of Ni-nitrate, Ni-halide, Ni-hydroxide, Ni- Nitrate, iron-halide, iron-hydroxide, iron-sulfate, cobalt-nitrate, cobalt Co-halide, cobalt-hydroxide, cobalt-sulfate, copper-nitrate, copper-halide, copper (Cu) -hydroxide, and copper (Cu) -sulfate. The method for producing a composite metal particle according to claim 1, The method according to claim 1,
And the standard reduction potential of the reducing agent is -0.23 V or less. The method according to claim 1,
Wherein the reducing agent is one or a mixture of two or more selected from the group consisting of NaBH ₄ , NH ₂ NH ₂ , LiAlH _4, and LiBEt ₃ H. delete delete A composite metal particle produced by the manufacturing method according to any one of claims 1 and 3 to 8. A catalyst comprising the composite metal particles of claim 11. The method of claim 12,
Wherein the catalyst further comprises a carrier capable of supporting the composite metal particles. 14. The method of claim 13,
Wherein the carrier is a carbon-based material or an inorganic fine particle. 15. The method of claim 14,
The carbon-based material may be carbon black, carbon nanotube (CNT), graphite, graphene, activated carbon, mesoporous carbon, carbon fiber, and carbon nano wire. &Lt; / RTI &gt; 15. The method of claim 14,
Wherein the inorganic fine particles are selected from the group consisting of alumina, silica, titania and zirconia. A fuel cell comprising the catalyst of claim 12.

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