KR101640212B1 - Composite nanoparticle deposited metal nanocrystal on its surface and method of preparing the same - Google Patents

Abstract

The present invention relates to a composite nanoparticle comprising a metal nanocrystal formed on the surface of a carbon shell, a method for producing the composite nanoparticle, and a battery electrode comprising the composite nanoparticle. More particularly, Metal nano-crystals, and exhibits high activity and durability, and thus can be usefully applied to fuel cells and the like.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite nanoparticle having metal nanocrystals bonded to its surface and a method for producing the composite nanoparticle.

The present invention relates to a composite nanoparticle comprising a metal nanocrystal formed on the surface of a carbon shell, a method for producing the composite nanoparticle, and a battery electrode comprising the composite nanoparticle. More particularly, Metal nano-crystals, and exhibits high activity and durability, and thus can be usefully applied to fuel cells and the like.

In the past, considerable attention was paid to the use of metal nanoparticles to develop effective catalytic materials. The smaller the particle size, the greater the surface exposure of active metal atom parts, and thus the nanoparticles showed improved catalytic activity. On the other hand, the large surface energy of the nanoparticles has resulted in sintering or coalescing, severe degradation of activity during catalysis, and hindering the use of industrial processes.

One effective way to avoid this inactivity problem is to use a suitable support metal to stabilize the dispersion of the nanoparticles in response to the sintering process. Due to its large surface area, its high degree of association with metal species, and its excellent stability to temperature, mechanical and oxidative stimuli, metal oxide nanoparticles have been regarded as candidates as solid supports for nanocatalyst systems.

In addition, the collective effect of metal / metal-oxide heterojunctions has often led to significantly improved catalyst results that could not be achieved with other unsupported catalysts. A polymer electrolyte fuel cell (FEP) is a fuel cell that uses a polymer membrane with hydrogen ion exchange properties as an electrolyte. It is also called a proton exchange membrane fuel cell (PEMPC). Pt / C catalysts have generally been used in the catalyst layers of polymer electrolyte fuel cells. However, since the Pt / C catalyst acts as a factor for increasing the price of a polymer electrolyte fuel cell, the fuel cell technology of the market still requires a catalyst material having high activity and durability.

The present invention aims to provide a composite nanoparticle comprising metal nanocrystals formed on the surface of a carbon shell through galvanic exchange reaction of nanoparticles containing manganese (II) oxide.

The present invention also provides a method for preparing composite nanoparticles comprising metal nanocrystals formed on the surface of a carbon shell through galvanic exchange reaction of nanoparticles containing manganese (II) oxide.

The present invention provides a battery electrode using composite nanoparticles containing metal nanocrystals formed on the surface of a carbon shell, and a battery including the same.

In studying galvanic exchange reaction using manganese oxide, different reaction modes were used in the galvanic exchange reaction of metals according to various oxidation states of manganese oxide. Manganese (II) oxide was easily dissolved in acidic state, In order to solve the problem that it can not participate in the galvanic exchange reaction in the precursor solution, manganese (II) oxide is placed inside the carbon shell to secure the acid stability and participate in the galvanic exchange reaction in the acidic metal precursor solution. Further, the present inventors confirmed that they exhibited different reaction patterns and bound metal nanocrystals selectively catalytically active on the outer or inner peripheral surface of the carbon shell.

Accordingly, the present invention can produce composite nanoparticles in which metal nanocrystals having selective catalytic activity are bonded to an outer peripheral surface and / or an inner peripheral surface of a carbon shell using various oxidation states of manganese oxide. Specifically, when a galvanic exchange reaction is performed after a step of forming a carbon shell on a manganese (II) oxide core, metal nanocrystals having catalytic activity can be bonded to the outer surface of the carbon shell, and manganese oxide (II , III) In the case of forming a carbon shell after bonding the metal nanocrystals having catalytic activity to the surface of the core first, metal nanocrystals having catalytic activity can be bonded to the inner circumferential surface of the carbon shell.

The metal nanocrystals having catalytic activity may be bonded to the outer circumferential surface and the inner circumferential surface of the carbon shell. The metal nanocrystals bonded to the outer circumferential surface and the metal nanocrystals bonded to the inner circumferential surface may be the same or different metals. In the case where different types of metal nanoparticles are respectively bonded to the outer and inner surfaces of the carbon shell, there is an advantage that two kinds of catalytic activities can be performed in one composite nanoparticle. The outer metal nanocrystals or the inner metal nanocrystals may be at least one metal selected from the group consisting of platinum, palladium, rhodium, and iridium.

In Korean Patent Laid-Open Publication No. 2009-0126057, the present inventors conducted a method of binding metal nanoparticles to manganese dioxide (II, III) nanoparticles using a galvanic exchange reaction with metal ions. However, manganese (II) (pH 4.0) and could not be used in acidic conditions. However, in the present invention, when manganese (II) oxide nanoparticles surrounded by a carbon shell are used, not only acid stability is secured but also the metal nanocrystals do not bind to the manganese (II) core and bind to the outer surface of the carbon shell . In addition, when the formation of the carbon shell and the order of the galvanic exchange reaction are changed to perform the galvanic replacement step first, the metal nanocrystals can be bonded to the inner circumferential surface of the carbon shell. Further, the inner circumferential surface and the outer circumferential surface can be bonded So that it is possible to impart catalytic function to each specific surface.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a method for preparing a carbon nanotube, comprising the steps of: preparing particles comprising a manganese (II) oxide core and a carbon shell; and performing a galvanic substitution reaction with a metal salt solution to form on the surface of said carbon shell a diameter of 0.5 to 5, And binding the metal nanocrystals of 1.4 to 2.6 nm to the composite nanoparticles.

The composite nanoparticle production method of the present invention is a method for producing composite nanoparticles comprising metal nanocrystals having a diameter of 0.5 to 5 nm, for example, 1 to 3 nm or 1.4 to 2.6 nm formed on the surface of a carbon shell, ) Composite nanoparticles comprising metal nanocrystals bonded to the outer surface of a carbon shell, (b) composite nanoparticles comprising metal nanocrystals bonded to the inner circumferential surface of a carbon shell, (c) bonding to both inner and outer surfaces of the carbon shell, And the metal nanocrystals can be provided.

In performing the galvanic exchange reaction with the metal salt solution, the galvanic exchange reaction according to the present invention may be performed at 50 ° C to 100 ° C for 0.5 to 12 hours. The metal salt solution may be a solution of the metal salt PtCl ₄ ^2- , PdCl ₄ ^2- , IrCl ₃ , or RhCl ₃ solution.

The composite nanoparticles according to the present invention may be nanoparticles having a diameter of 20 to 50 nm, for example, 23 to 29 nm. The thickness of the carbon shell may be between 5 and 10 nm, for example between 7.2 and 8.6 nm.

An example of the present invention provides a method for producing composite nanoparticles comprising metal nanocrystals bonded to the outer surface of a carbon shell.

Specifically, a dopamine polymer layer is formed on the surface of manganese (II, III) manganese core and reacted at 400 to 600 ° C, for example 500 ° C, for 1 to 10 hours, for example 5 hours, A process for producing particles comprising a manganese (II) core and a carbon shell,

And performing a galvanic substitution reaction with a metal salt solution to bind metal nanocrystals having a diameter of 0.5 to 5 nm, for example, 1 to 3 nm, on the outer surface of the carbon shell.

The step of reacting in the reducing atmosphere to produce a manganese (II) oxide core and a carbon shell may be carried out by a carbonization reaction in which a carbon shell is formed and a carbon thermal reduction reaction in which manganese dioxide (II, III) .

The composite nanoparticles including the metal nanocrystals bonded to the outer circumferential surfaces of the manganese (II) oxide core, the carbon shell and the carbon shell are removed by removing the manganese (II) oxide core with an acid solution, The composite nanoparticles comprising the metal nanocrystals bonded to the metal nanoparticles can be produced.

Another embodiment of the present invention provides a method for producing composite nanoparticles comprising metal nanocrystals bonded to the inner circumferential surface of a carbon shell.

Specifically, before forming a dopamine polymer layer on the surface of the manganese (II, III) core, a galvanic substitution reaction is performed with a metal salt solution on the surface of the manganese (II, III) III) a diameter of 0.5 to 5 nm, for example 1 to 3 nm, on the outer surface of the core. Or a metal nanocrystal of 1.7 to 2.3 nm is bonded to produce a manganese oxide (II, III) core to which metal nanocrystals are bonded, and

A doping polymer layer is formed on the manganese oxide (II, III) core to which the metal nanocrystals are bonded to form a carbon shell in a reducing atmosphere, and a carbonization reaction in which manganese dioxide (II, III) For example, at 500 ° C for 1 to 10 hours, for example, for 5 hours under a reducing atmosphere to form a carbon shell having a diameter of 0.5 to 5 nm, For example, 1 to 3 nm or 2.2 to 3.4 nm of metal nanocrystals.

The composite nanoparticles comprising the manganese (II) oxide core, the metal nanocrystals, and the carbon shell are subjected to a step of removing the manganese (II) oxide core with an acid solution to form a hollow carbon shell and metal nanocrystals bonded to the inner periphery thereof Can be produced.

In another embodiment of the present invention, there is provided a method for producing composite nanoparticles comprising (c) metal nanocrystals bonded to both inner and outer surfaces of a carbon shell.

Specifically, before forming a dopamine polymer layer on the surface of the manganese (II, III) core, a galvanic substitution reaction is performed with a metal salt solution on the surface of the manganese (II, III) III) a process for producing a manganese oxide (II, III) core to which metal nanocrystals are bonded by bonding metal nanocrystals having a diameter of 0.5 to 5 nm, for example, 1.7 to 2.3 nm,

A dopamine polymer layer is formed on the manganese (II, III) core of manganese oxide to which the metal nanocrystals are bonded and reacted at 400 to 600 ° C, for example 500 ° C, for 1 to 10 hours, A step of binding metal nanocrystals having a diameter of 0.5 to 5 nm, for example, 2 to 3.5 nm, on the inner peripheral surface of the carbon shell,

And a step of binding metal nanocrystals having a diameter of 0.5 to 5 nm, for example, 1 to 3 nm, on the outer circumferential surface of the carbon shell to which the metal nanocrystals are bonded, by performing a galvanic substitution reaction with the metal salt solution.

The composite nanoparticles comprising metal nanocrystals bonded to the inner circumferential surface and the outer circumferential surface of the manganese (II) oxide core, the carbon shell, and the carbon shell are subjected to a step of removing the manganese (II) oxide core with an acid solution, It is possible to produce composite nanoparticles containing metal nanocrystals bonded to the inner peripheral surface and the outer peripheral surface.

The metal nanocrystals (a) bonded to the outer circumferential surface of the carbon shell and (b) the metal nanocrystals bonded to the inner circumferential surface of the carbon shell may be one or more metal nano-crystals. The (c) metal nanocrystals bonded to both the inner circumferential surface and the outer circumferential surface of the carbon shell may be the same or different metal nanocrystals.

The present invention relates to a composite nanoparticle comprising a metal nanocrystal formed on the surface of a carbon shell, a method for producing the composite nanoparticle, and a battery electrode comprising the composite nanoparticle. More particularly, The metal nanocrystals were fabricated and the nanoparticles with high density were stably immobilized on the surface of the nanoparticles uniformly. The proton exchange membrane fuel cell (PEMPC: Proton Exchange Membrane Fuel Cells show high activity and durability compared with existing Pt / C catalysts and can be applied to fuel cells and the like. In addition, the composite nanoparticles according to the present invention can be bonded by dividing metal nanoparticles having two different catalytic activities into an outer peripheral surface and an inner peripheral surface of a carbon layer.

FIG. 1 is a schematic view showing a method of attaching metals having catalytic properties to different inside and outside of hollow carbon nanoparticles according to an embodiment of the present invention.
FIG. 2 is a photograph showing an HRTEM photograph of manganese (IV) oxide and a manganese (II) oxide and a result of XRD pattern analysis. (II) @ transmission electron microscope and high quality transmission electron microscope (inside) of carbon and (c) X-ray diffraction analysis pattern of carbon. The line below shows that this material is the same as the tetragonal manganese dioxide (II, III) form (JCPDS Card No. 80-0382) and manganese (II) form (JCPDS Card No. 78-0424) have.
(B) high-quality transmission electron micrographs of (a) a carbon-carbon double bond (284.6 eV) of a carbon-1s electron, (b) X-ray photoelectron spectroscopy, decomposed into four elements, respectively, of carbon-nitrogen single bond (285.5 eV), carbon-nitrogen double bond (286.5 eV) and carbon (benzene) ) Is a x-ray photoelectron spectroscopic curve decomposed into two elements: a carbon-nitrogen double bond (398.5 eV) and a carbon-nitrogen single bond (400.2 eV)
FIG. 4 is a graph showing the results of a reaction between a carbon nanoparticle (manganese (II) oxide) and a sodium chloroplatinate solution at 100 ° C for 5 minutes, (b) 10 minutes, (c) Microscope, a high-resolution transmission electron microscope (inside) photograph, and a histogram showing the size distribution of platinum nanoparticles bound to the carbon skin.
FIG. 5 shows a transmission electron microscope and a high-quality transmission electron microscope of a sample obtained by reacting carbon nano-particles (II) @ carbon nanoparticles with a sodium chloroplatinate solution at 70 ° C., (b) 50 ° C., and (c) ) Picture.
FIG. 6 is a transmission electron microscope image obtained by reacting (a) manganese oxide (II) @ carbon and (b) manganese oxide (II) @ silica nanoparticles in an acidic solution of pH 1.4 at room temperature for 24 hours.
FIG. 7 is a graph showing the results of the oxidation of manganese (II) chloride in a supernatant obtained by dissolving manganese (II) nuclei using hydrochloric acid in a carbon nanoparticle (II) It is a transmission electron micrograph obtained by reacting manganese (II) nucleus with free-standing carbon nanoparticles and chloroplatinic acid sodium.
FIG. 8 is an X-ray diffraction analysis pattern of manganese oxide (II, III) carbon nanoparticles prepared by (a) oxidizing manganese (II) carbon nanoparticles through a hydrothermal synthesis reaction. (c) Manganese (II) oxide Carbon nanoparticles were dissolved in chloroformate (1 mg / ml, pH 2.4) at 70 ° C for 30 minutes (left), 1 Time (middle), 2 hours (right), and then a transmission electron microscope and a high-quality transmission electron microscope (inside) photograph.
FIG. 9 is a graph showing the results of measurement of manganese oxide having a carbon skin thickness of 7.6 (± 0.9) nm, (b) 4.9 (± 0.4) nm and (c) 3.1 Transmission electron microscope, high-quality transmission electron microscope (inside) picture of the specimen obtained by reaction with sodium solution over time.
FIG. 10 is a graph showing the relationship between manganese and platinum by (a) transmission electron microscopy, high quality transmission electron microscopy, scanning transmission electron microscopy, and energy scattering spectroscopic analysis of manganese (II) oxide @ carbon @ platinum oxide and (b) hollow carbon nanoparticles Scanning transmission electron microscope capable of line distribution analysis. The histogram shows the size distribution of attached platinum nanoparticles. (c) Scanning electron microscope illustration of hollow carbon nanoparticles @ platinum. (d) hollow carbon nanoparticles (transmission electron microscope) of hollow carbon nanoparticles obtained by melting platinum nanoparticles attached to the surface of platinum.
FIG. 11 is a graph showing the transmission electron microscope (TEM) of (a) manganese (II) oxide, (b) manganese (II) carbon rhodium, (c) manganese It is an electron microscope (inside) figure.
FIG. 12 shows a transmission electron microscope, scanning electron microscope-energy scattering spectroscopy analysis of iridium (a) hollow carbon nanoparticles, palladium, (b) hollow carbon nanoparticles, Scanning transmission electron microscope capable of line distribution analysis of precious metals The histogram shows the size distribution of the noble metal nanoparticles attached.
13 is a graph showing the transmittance of (a) manganese (II, III) platinum, (b) manganese (II, III) platinum dopamine polymer, (c) manganese Electron microscope and high-quality transmission electron microscope (inside) picture. The histogram shows the size distribution of attached platinum nanoparticles.
FIG. 14 is a graph showing the relationship between the amount of platinum and the amount of free carbon nanoparticles, (b) platinum, (c) platinum, (e) Transmission electron microscope and high-quality transmission electron microscope (inside) picture of platinum @ hollow carbon nanoparticle @ iridium. The histogram shows the size distribution of the bound metal nanoparticles. (c) ~ (e), respectively, are platinum, p-type carbon nanoparticles, palladium, platinum, and carbon nanoparticles, rhodium, platinum, and free carbon nanoparticles, Figures and elemental distributions (platinum: green, palladium: yellow, rhodium, red, iridium: purple)
15 shows (a) the oxygen reduction reaction polarization curve of the three catalysts analyzed at a rotation speed of 1600 rpm and a scanning speed of 10 mV / s in a 0.1 M hypochlorous acid solution saturated with oxygen. (b) A graph of the linear voltage electrode method through an oxygen generating reaction in a 0.1 M hypochlorous acid solution saturated with nitrogen.
FIG. 16 is a graph (scanning speed is 50 mV / s) obtained by cyclic voltammetry measurement using three catalysts in 0.1 M hypochlorous acid solution saturated with nitrogen.

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not intended to be limited by these examples.

Example  One:

Example  1-1: Manganese oxide ( II , III ) @ Dopamine polymer nanoparticles

To prepare manganese (II) oxide nanoparticles, first prepare manganese dioxide (II, III) @ dopamine polymer nanoparticles.

Manganese dioxide (II, III) nanoparticles without a surfactant were polymerized in a Tris buffer solution (pH 8.5) by the basic action of dopamine molecules on the nanoparticles to form nanoparticles surrounded by dopamine polymer films II, III) @ dopamine polymer nanoparticles) were prepared. (II, III) @ dopamine polymer nanoparticles obtained through reaction in an air atmosphere for 24 hours were subjected to a transmission electron microscope (TEM), a high-resolution transmission electron microscope (HR-TEM), and X- And observed using diffraction (XRD), which is shown in Fig. Transmission electron microscopy (TEM) analysis was performed with JEOL JEM-2010, and the X-ray diffraction pattern was obtained using an X-ray diffractometer (18 kW) (Mac Science, Japan).

As shown in FIG. 2 (a), a dopamine polymer film having a thickness of 7.6 (± 0.9) nm was found to surround the manganese oxide (II, III) nanoparticles having a diameter of 19 (± 3) nm .

Example  1-2: Manganese oxide ( II ) @ Carbon nanoparticles

The doped manganese (II, III) @ dopamine polymer nanoparticles prepared in Example 1-1 was reacted at 500 ° C for 5 hours while flowing Ar and 4% H ₂ , and the dopamine polymer film was changed into a carbon skin Manganese (II) oxide carbon nanoparticles were prepared. At a high temperature of 500 ° C, the hydrogen film of the polymer film is flushed with carbon, and the dopamine polymer film is replaced with a carbon shell. At the same time, the substituted carbon shells reduce manganese oxide to manganese oxide through a carbon thermal reduction reaction that reacts with manganese dioxide (II, III) in the core as follows. Mn ₃ O ₄ + C - > 3MnO + CO. The carbonization reaction and the carbon thermal reduction reaction occurred simultaneously at 500 ° C.

 The manganese (II) oxide nanoparticles were observed using a transmission electron microscope (TEM), a high-resolution transmission electron microscope (HR-TEM), and X-ray diffraction (XRD). Raman spectra, high-resolution transmission electron microscopy (HR-TEM) and nuclear magnetic resonance spectroscopy of the manganese (II) oxide nanocomposites were determined. The results are shown in FIG.

(B) high-quality transmission electron micrographs of (a) a carbon-carbon double bond (284.6 eV) of a carbon-1s electron, (b) X-ray photoelectron spectroscopy, decomposed into four elements, respectively, of carbon-nitrogen single bond (285.5 eV), carbon-nitrogen double bond (286.5 eV) and carbon (benzene) ) Shows an x-ray photoelectron spectroscopy curve decomposed into two elements: a carbon-nitrogen double bond (398.5 eV) and a carbon-nitrogen single bond (400.2 eV).

As shown in FIG. 2 and FIG. 3, it was found that the carbon skin was composed of amorphous carbon mainly composed of sp2-bond and 13% was composed of nitrogen atoms. X-ray diffraction analysis (XRD) showed that the dopamine polymer shell changed to carbon and manganese dioxide (II, III) became a more reduced form of manganese oxide (II). The size of manganese oxide is 19 (± 0.3) nm, and the thickness of carbon skin is 7.9 (± 0.7) nm. The change of manganese dioxide (II, III) to manganese oxide (II) is only possible when the temperature is higher than 1300 ℃. The reaction between manganese dioxide and manganese oxide (II, III) It was found by the reaction.

Example  1-3: Manganese oxide ( II ) @ Carbon nanoparticles Galvanic  reaction

Manganese (II) oxide nanoparticles (1.0 mg / ml) were dissolved in sodium chloride platinate solution (Na2PtCl4, 5.0 mg / ml, pH 3.2) and reacted at 100 ℃.

Specifically, manganese (II) oxide nanoparticles were reacted at 100 ° C for 5 minutes, (b) for 10 minutes, (c) for 20 minutes, and (d) for 30 minutes, After cooling at room temperature, the resulting solution was separated using a centrifuge and purified by dispersion in suspension and centrifugation three times. The purified nanoparticles were analyzed by a transmission electron microscope (TEM) and a high-resolution transmission electron microscope (HR-TEM), and a histogram showing the particle size distribution was displayed. The results of the analysis are shown in Fig. The histogram showed the size distribution of the platinum nanoparticles bound to the carbon shell

As shown in FIGS. 4 (a) to 4 (d), the reaction suspension was slightly taken at different times and analyzed by a transmission electron microscope (TEM). As a result, It was not long after the start (from 5 minutes), as shown in Fig. 4 (a). As the reaction progresses, the number of platinum nanoparticles on the outer surface of the manganese (II) oxide nanocomposite increases between 5 and 30 minutes and increases in size from 1.5 (± 0.3) to 1.9 (± 0.3) nm .

This galvanic exchange reaction was confirmed by the high-frequency inductively coupled plasma atomic emission spectrometry (ICP-AES) analysis as the reaction progressed and the MnO nuclei slowly melted and platinum grew (Table 1). Table 1 shows the concentrations of manganese and platinum measured by separating the supernatant after centrifuging and taking 0.5 ml of the suspension over time while progressing the reaction to grow platinum nanoparticles on the manganese (II) oxide nanocomposite. All concentrations were measured by high frequency inductively coupled plasma atomic emission spectrometry.

5 minutes 10 minutes 20 minutes 30 minutes 1 hours 4 hours Mn (ug) 52 110 187 231 281 370 Pt (ug) 1.39 1.27 952 723 464 65

Example  2

Manganese (II) oxide carbon nanoparticles were prepared in substantially the same manner as in Examples 1-1 and 1-2. Then, the galvanic reaction of manganese (II) oxide nanoparticles was carried out in substantially the same manner as in Example 1-3, except that the reaction temperature of Example 1-3 was changed from 70 ° C to 50 ° C to room temperature And the resulting sample was analyzed by a transmission electron microscope and a high-quality transmission electron microscope (inside), and the results are shown in FIG. 5 shows a transmission electron microscope and a high-quality transmission electron micrograph of a sample obtained by (a) reacting at 70 ° C, (b) 50 ° C, and (c) room temperature.

As shown in FIG. 5, the manganese oxide @ carbon nanoparticles show a slower reaction rate at 70 ° C and 50 ° C, and a smaller amount of platinum sticks at the same time. At room temperature, platinum does not grow at all.

Example  3: Evaluation of acid stability

The manganese oxide (II) @ carbon nanoparticles obtained in Example 1-2 When it was left in diluted hydrochloric acid solution (pH 3.2) and 100 ° C for 12 hours, it was confirmed that nothing was dissolved. This can be explained as a significant increase in the resistance to acids of manganese (II) nuclei surrounded by carbon shells containing large amounts of nitrogen atoms. The stability to the acid solution was demonstrated by surviving in a stronger acid solution (pH 1.4).

(II) @ carbon and manganese oxide (II) @ silica of Example 1-2 (J. Mater. Chem. 2010,20, 10615-10621), manganese oxide (II) @ silica nanoparticles of silica shell Manganese (II) oxide (II, III), which is prepared by dissolving in 3M sodium hydroxide solution, manganese (II) oxide (II, III) The nanoparticles were reacted for 24 hours at pH 1.4 in an acidic solution and at room temperature, and analyzed by transmission electron microscopy. The results are shown in FIG. As shown in FIG. 6, the manganese (II) oxide core of the manganese (II) oxide is still present (FIG. 6A), whereas the manganese (II) (Fig. 6 (b)). Furthermore, the manganese (II) oxide manganese oxide (II, III) nanoparticles completely melted and could not be separated by centrifugation.

Example  4: Pervasive  Manufacture of carbon nanoparticles

Manganese (II) oxides Manganese (II) oxide from carbon nanoparticles Free radical carbon nano-particles and platinum chloride are removed from manganese (II) solution or manganese oxide (II) No platinum metal particles could be observed when reacted with a solution of hydrochloric acid of pH 3.2 dissolved in water for 12 hours (FIG. 7). FIG. 7 (a) is a result of reacting the hollow carbon nanoparticles prepared by removing the manganese (II) nucleus from the carbon nanoparticles and the platinum chloride with the manganese (II) chloride solution, Is the result of the reaction of inert and carbon nanoparticles from which manganese (II) oxide nanoparticles have been removed from carbon nanoparticles and a solution of manganese (II) oxide nanoparticles dissolved in hydrochloric acid.

As shown in Fig. 7, it is proved that the manganese (II) oxide nucleus having increased stability by the carbon shell is the cause of binding of platinum to the surface of manganese (II) oxide nanocomposite. The binding of platinum nanoparticles to the surface of manganese (II) oxide is due to a galvanic exchange reaction in which platinum chloride ions are reduced to platinum metal and manganese (II) oxide is oxidized to manganese ions (II). The above Galvanic exchange reaction is shown in the following Reaction Scheme 1.

[Reaction Scheme 1]

^{PtCl4 2- + 2MnO (s) +} 4H + → Pt (s) + 2Mn 3+ + 4Cl- + 2H 2 O (1)

Comparative Example  One: Manganese oxide ( II , III ) @ Carbon nanoparticles Galvanic  reaction

The XRD pattern of manganese oxide (II, III) carbon nanoparticles made by oxidizing manganese (II) carbon nanoparticles through a hydrothermal synthesis reaction is shown in 9a. (Manganese (II) oxide) carbon nanoparticles were dissolved in distilled water and reacted in an air atmosphere autoclave at 200 ° C for 24 hours.

Carbon nanoparticles prepared from the prepared manganese dioxide (II, II) carbon shell and the manganese (II) oxide prepared in Example 1-2 were dissolved in a solution of sodium chloride platinate (1 mg / ml, pH 2.4) (Left side in Figs. 8B and 8C), 1 hour (in the middle of Figs. 8B and 8C), 2 hours (right side in Figs. 8B and 8C), and a transmission electron microscope and a high- FIG. 8 (b) shows the result of galvanic reaction of manganese (II, III) carbon, and FIG. 8 (c) shows the result of galvanic reaction of manganese (II) carbon nanoparticles.

As shown in FIG. 8, in contrast to the fact that the growth of platinum in manganese (II) carbon nanoparticles is made on the outermost surface of the carbon skin rather than in the manganese (II) core, In the galvanic exchange reaction of manganese (II, III) carbon nanoparticles with platinum ions, it was found that platinum nanoparticles grow very slowly and only in manganese dioxide (II, III) nuclei. The fact that platinum nanoparticles grow at a fast rate only on the outermost surface of the carbon shell in the case of manganese (II) oxide nanoparticles can be attributed to the fact that the manganese (II) / manganese (II) ) / Manganese ion (II) pair (reduction potential difference: ΔEred ° = -0.406 V). This difference is due to the fact that manganese oxide (II, III) (II), the surface becomes more positively charged in the galvanic exchange reaction with the platinum chloride ion. This large redox potential is obtained by the redox reaction through the galvanic exchange reaction, in which the chlorine platinum ion receives electrons from the manganese (II) nucleus inside the carbon shell through the carbon nano shell as a conductor and is reduced to platinum, Lt; / RTI > This is because when the carbon shell of carbon nanoparticles has a high electrical conductivity and has many defects and galvanic exchange reaction occurs, the electrons and manganese ions (II) are released out of the carbon shell while the platinum ions are oxidized Manganese (II) nucleus.

Example  5: Effect according to various carbon skin thickness

(A) 7.6 (± 0.9) nm, (b) 4.9 (± 0.4) nm and (c) 3.1 (± 0.3 nm) carbon bark in substantially the same manner as in Examples 1-1 and 1-2. Manganese oxide @ carbon nanoparticles having a thickness of 30 nm were prepared. The above-mentioned manganese oxide (Manganese oxide) was reacted with a sodium chloroplatinic acid solution at 70 ° C to obtain a sample at reaction times of 0, 10, 20 and 30 minutes. Each sample was observed under a transmission electron microscope and a high-quality transmission electron microscope ). The results are shown in Fig. In FIG. 9, (a) represents manganese oxide having carbon shell thickness of 7.6 (± 0.9) nm, (b) 4.9 (± 0.4) nm and (c) 3.1 (± 0.3 nm).

When the thickness of the carbon shell is 4.9 (± 0.4) nm and 7.6 (± 0.9) nm, it is possible to produce platinum Nanoparticles grow on the outermost surface of the carbon skin. When the thickness of the carbon shell is 3.1 (± 0.3) nm, the platinum nanoparticles first attach to the inner surface of the manganese oxide (II) within about 10 minutes from the start of the reaction. As the reaction progresses, II). The transmission electron microscope images were observed by measuring the reaction time. It was found that the thickness of the carbon skin should be 3 nm or more in order for the galvanic exchange reaction to occur only on the outer surface of the carbon shell by inhibiting the entry of the platinum ion into the carbon shell through this phenomenon. As a result, manganese oxide (II) having a carbon skin thickness of 7.9 (± 0.7) nm @ carbon nanoparticles was reacted in a sodium chloride platinate solution for 12 hours to obtain small platinum nanoparticles having a size of 2.1 (± 0.3) (II) @ carbon @ platinum nanocomposite with a core of 4.3% manganese (II) nucleus clustering tightly on the outer surface of the carbon nano-shell and surrounded by a carbon nano-shell 9 (a)).

Example  6: Inner bin Of carbon nanoparticles  On the outer surface Combined  Nanoparticle

It has been confirmed that it is possible to attach catalytic nanoparticles to specific surfaces of hollow carbon nanoparticles using manganese (II) oxide @ carbon @ platinum nanoparticles.

When the manganese oxide (II, III) @ carbon @ platinum nanoparticles prepared in Example 4 were immersed in a nitric acid solution having a pH of 1.0, only the manganese (II) nucleus remaining unaffected by the platinum nanoparticles was completely dissolved and 17 (± 3) Only the inner empty space of nm was left. As a result, hollow carbon nanoparticles (platinum nanoparticles), in which very small platinum nanoparticles are tightly bound only on the outer surface, were prepared, which can be applied as an electrochemical catalyst. Platinum was attached to the outermost surface to characterize the specific surface of the hollow nanoparticles. Transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), energy scattering spectroscopy (EDX) line element analysis method, and the results are shown in Figs. 10 (b) to (d).

10 (a) shows a transmission electron microscope, a high-quality transmission electron microscope, a scanning transmission electron microscope-energy scattering spectroscopic analysis of platinum of manganese (II) oxide @ carbon @ platinum, The histograms of (a) and (b) show the size distribution of the bound platinum nanoparticles. The results are shown by transmission electron microscope of particles, platinum, high-quality transmission electron microscope, scanning transmission electron microscope-energy scattering spectroscopy.

Example  7: Coupling of palladium, rhodium and iridium

Example  7-1: Manganese oxide ( II ) @ Carbon @ metal nanoparticles

Using the same method as in Example 1, manganese (II) oxide nanoparticles immersed in sodium chloride palladium chloride, rhodium chloride, and iridium chloride solution as well as platinum were subjected to a galvanic exchange reaction to obtain 2.2 ( (± 0.4), 2.0 (± 0.3), and 1.6 (± 0.2) nm of palladium, rhodium, and iridium nanoparticles. 11 shows the transmission electron microscope and high-quality transmission of (a) manganese (II) oxide, (b) manganese (II) oxide and (c) manganese (II) Electron micrograph (inside) photograph, and each figure shows the histogram showing the particle size of the combined metal particles.

Example  7-2: Pervasive  Manganese oxide ( II ) @ Carbon @ metal nanoparticles

When the manganese (II) oxide is dissolved in the produced manganese (II) oxide nanocomposite, various noble metals having catalytic properties are attached to the outer surface of the hollow nanoparticle metal (metal = palladium, rhodium , Iridium) nanoparticles were obtained. Specifically, if the prepared manganese oxide (II) @ carbon @ metal nanoparticles are immersed in a nitric acid solution having a pH of 1.0, only the core of the manganese (II) oxide remaining unaffected by the platinum nanoparticles is completely dissolved, .

In FIG. 12, a transmission electron microscope, a scanning transmission electron microscope, and an energy scattering spectroscopy analysis image of (a) hollow carbon nanoparticles, (b) hollow carbon nanoparticles, (rhodium) and (c) hollow carbon nanoparticles, The histogram shows the size distribution of the noble metal nanoparticles attached.

Example  8: Pervasive Of carbon nanoparticles  Inside and On the outer side  Metal particle bonding

Example  8-1: Of carbon nanoparticles  Metal particle bonding inside

This method attaches nanoparticles with catalytic properties to the inner surface of hollow nanoparticles. First, platinum nanoparticles (manganese oxide (II, III) @ platinum) of 2.0 (± 0.3) nm in size were attached to the outer surface of manganese oxide (II, III) nanoparticles without surfactant using a galvanic exchange reaction Respectively.

(II, III) nanoparticles in which platinum nanoparticles were bonded to the outer surface were coated with carbon using a dopamine polymer (FIGS. 13 (a) and 13 (b)). Specifically, in a similar manner to Example 1-1, manganese (II, III) nanoparticles of manganese oxide (II, III) having platinum nanoparticles bonded to its outer surface were polymerized in a Tris buffer solution (pH 8.5) The reaction was carried out to prepare nanoparticles (manganese dioxide (II, III) @ platinum @ dopamine polymer) surrounded by a dopamine polymer film. Further, a manganese (II, III) platinum (Pt) dopamine polymer was reacted at 500 ° C. for 5 hours while flowing Ar and 4% H ₂ in substantially the same manner as in Example 1-2 to obtain a dopamine polymer film (II) < / RTI > platinum < / RTI > carbon nanoparticles were prepared. The above-mentioned manganese (II) oxide platinum nanoparticles were observed using a transmission electron microscope (TEM), a high-resolution transmission electron microscope (HR-TEM), and X-ray diffraction (XRD) .

13 is a graph showing the transmittance of (a) manganese (II, III) platinum, (b) manganese (II, III) platinum dopamine polymer, (c) manganese The electron microscope, high-resolution transmission electron microscope (inside) photograph, and histogram show the size distribution of attached platinum nanoparticles. Platinum nanoparticles of 2.8 (± 0.6) nm in size, slightly increased in size during the bending process through the transmission electron microscope image of the manganese (II) oxide (platinum) carbon nanoparticles, are attached between the manganese (II) oxide core and the carbon skin (Fig. 13C).

Example  8-2: Pervasive Of carbon nanoparticles  Metal particle bonding inside

Removal of manganese (II) oxide (Pt) @ carbon nanoparticles from manganese (II) oxide using a nitric acid solution results in the formation of an internal void and the formation of platinum nanocarbon nanoparticles with platinum nanoparticles attached only to the inner surface of the hollow carbon nanoparticles 14 (a)). With this method, the inner and outer surfaces of the hollow carbon nanoparticles can be decorated with nanoparticles having the same or different catalytic properties, respectively.

Example  8-3: Of carbon nanoparticles  Combine the same metal particles inside and outside

When the manganese (II) oxide platinum (Pt) carbon nanoparticles obtained in Example 8-2 were reacted in a sodium chloride platinate solution solution, additional platinum nanoparticles adhered to the outer surface of the carbon skin. In this process, the inner manganese oxide (II ) Is completely dissolved. As a result, platinum (hollow carbon nanoparticles) platinum nanoparticles having both inner and outer surfaces decorated with platinum nanoparticles were obtained (FIG. 14B).

Example  8-4: Of carbon nanoparticles  Combination of different metal particles inside and outside

When the hollow manganese (II) oxide platinum (Pt) carbon nanoparticles obtained in Example 8-3 were reacted with sodium chloride palladium chloride solution, rhodium chloride solution and iridium chloride solution, respectively, in substantially the same manner as in Example 7, (Metal = palladium, rhodium, iridium) nanocomposites, each of which was decorated with nanoparticles of platinum and other catalytic properties, respectively. (Fig. 14C-e)

FIG. 14 is a graph showing the results of the measurement of (a) platinum particle, (b) platinum particle, (c) platinum particle, e) platinum @ hollow carbon nanoparticle @ transmission electron microscope and high-quality transmission electron microscope (inside) of iridium, and the histogram shows the size distribution of the attached metal nanoparticles. 4 (c) to 4 (e) are the transmission electron micrographs of elemental platinum (spontaneous carbon nanoparticles), palladium (platinum), free carbon nanoparticles (rhodium) and platinum (Platinum: green, palladium: yellow, rhodium, red, iridium: purple).

Example  9: Platinum @ Pervasive Carbon nanoparticles @ Double Electrochemical Catalytic Reaction Evaluation of Iridium Nanoparticles

Example  9-1: Pervasive Of carbon nanoparticles  Inside and On the outer side  Different metal particles Combined  particle

In order to demonstrate the usefulness of the metal nanoparticles of the present invention, which have different catalytic functions on the inner and outer surfaces of the hollow carbon nanoparticles prepared in Example 8-4, We confirmed the catalytic activity of two functions of oxygen reduction reaction (ORR) and oxygen generation reaction (OER) of carbon nanoparticles @ iridium nanoparticles. The electrochemical catalytic activity for this reaction is important in the secondary fuel cell field.

Specifically, the oxygen reduction reaction polarization curve of the three catalysts analyzed at a rotation speed of 1600 rpm and a scanning speed of 10 mV / s in a 0.1 M hypochlorous acid solution saturated with oxygen was shown in FIG. 15 (a). In FIG. 15 (a), three catalysts were placed on a glassy carbon rotation plate electrode (RDE) in a 0.1 M hypochlorous acid solution saturated with oxygen by a linear voltage-current method to measure the catalytic activity for the oxygen reduction reaction (ORR). Through this oxygen reduction (ORR) polarization curves, it was found that the reactivity of the electrochemical catalytic reaction of platinum @ sparse carbon nanoparticles @ iridium catalyst was better than that of commercially available platinum / carbon catalysts, It was found that the platinum catalyst bonded to the inner surface had reactivity as an electrochemical catalyst in an oxygen reduction reaction (ORR).

When the electrochemically active surface area (ESCA) of the platinum was measured by measuring the hydrogen adsorption potential by the cyclic voltammetry method (FIG. 16), it was confirmed that the platinum / inert carbon nanoparticles Able to know.

Example  9-2: Pervasive Of carbon nanoparticles On the outer side  Different metal particles Combined  particle

In contrast, the polarization curves of the spontaneous carbon nanoparticles, iridium / platinum nanoparticles, in which both iridium and platinum are bonded to the outer surface of the free carbon nanoparticles, show that the platinum @ free carbon nanoparticles @ iridium nanoparticles and platinum / carbon The potential was lowered by about 70 mV. The reason why the activity of the oxygen reduction reaction (ORR) is low when the platinum and the iridium are attached together on the carbon surface is that the oxygen adsorption energy of the platinum is increased by the interaction of the platinum and the iridium, . The platinum nanoparticles of the hollow carbon nanoparticles (platinum / iridium nanoparticles) strongly adsorb oxygen on the surface, so that oxygen desorption at a higher voltage is achieved in the cyclic voltammetry measurement (FIG. 15).

FIG. 15 (b) shows a graph of the linear voltage-current method for the oxygen generation reaction (OER) of the three catalysts. Dislocations are prominent when platinum / carbon catalysts are compared to those containing iridium, indicating that platinum has low electrochemical catalytic reactivity in the oxygenation reaction (OER). The dislocations of platinum @ sparse carbon nanoparticles @ iridium nanoparticles and hollow carbon nanoparticles @ platinum / iridium nanoparticles were almost similar. However, Fig. 15 (b) shows that the activity of the platinum @ hollow carbon nanoparticles < RTI ID = 0.0 > iridium < / RTI > nanoparticles is better than that of the oxygen generating reaction (OER) activity of platinum / carbon nanoparticles. FIG. 15 shows that iridium, a platinum particle, has a catalytic function for two reactions, an oxygen reduction reaction (ORR) and an oxygen generation reaction (OER). Separating two different catalytically active metal nanoparticles, such as platinum and iridium, through the carbon layer allows their unique electrochemical catalysis to be performed without degrading the activity as seen in the oxygen reduction reaction (ORR). Respectively.

Claims (26)

A doping polymer layer is formed on the surface of a manganese (II, III) oxide core and a carbonization reaction in which a carbon shell is formed in a reducing atmosphere and a carbonization reaction in which manganese dioxide (II, III) Reaction was carried out to prepare particles containing a manganese (II) oxide core and a carbon shell,
And performing a galvanic substitution reaction with a metal salt solution to bind external metal nanocrystals having a diameter of 0.5 to 5 nm to the surface of the carbon shell.
delete delete The method of claim 1, wherein the particles comprising the manganese (II) oxide core and the carbon shell further comprise an inner metal nanocrystal bonded to the inner circumferential surface of the carbon shell.
5. The method of claim 4, wherein, prior to forming the dopamine polymer layer, a galvanic substitution reaction is performed on the manganese (II, III) manganese core with a metal salt solution, 5 nm inner metal nanocrystals were bonded,
A doping polymer layer is formed on the surface of the carbon shell and a carbonation reaction in which a carbon shell is formed in a reducing atmosphere and a carbon thermal reduction reaction in which manganese dioxide (II, III) is manganese oxide (II) To produce particles comprising a manganese (II) oxide core and a carbon shell further comprising 0.5 to 5 nm metal nanocrystals bonded to said metal nanocrystals.
6. The method of claim 5, further comprising performing a step of bonding the outer metal nanocrystals followed by removing the manganese (II) oxide core with an acid solution to produce a hollow carbon shell.
5. The method of claim 4, wherein the outer metal nanocrystals and the inner metal nanocrystals are different kinds of metals.
The method according to any one of claims 1 to 7, wherein the outer metal nanocrystals or the inner metal nanocrystals are at least one metal selected from the group consisting of platinum, palladium, rhodium, and iridium.
8. The method of any one of claims 1 to 7, wherein the metal nanocrystals have a diameter of 0.5 to 5 nm.
8. The method of any one of claims 1 to 7, wherein the composite nanoparticles are nanoparticles having a diameter of from 20 to 50 nm.
8. The method according to any one of claims 1 to 7, wherein the galvanic substitution reaction is performed at 50 DEG C to 100 DEG C.
8. The method according to any one of claims 1 to 7, wherein the galvanic substitution reaction is carried out for 0.5 to 12 hours.
The method of claim 1, wherein the solution of the metal salt is PtCl ₄ ^2- , PdCl ₄ ^2- , IrCl ₃ , or RhCl ₃ solution.
The method of claim 1, wherein the thickness of the carbon shell is between 5 and 10 nm.
A composite nanoparticle prepared by the method according to claim 1 and comprising an outer metal nanocrystal having a diameter of 0.5 to 5 nm formed on the outer surface of the carbon shell.
16. The composite nanoparticle according to claim 15, wherein the composite nanoparticle further comprises an inner metal nanocrystal having a diameter of 0.5 to 5 nm formed on an inner peripheral surface of the carbon shell.
17. The composite nanoparticle of claim 15 or 16, wherein the carbon shell comprises a MnO core therein.
17. The composite nanoparticle of claim 15 or 16, wherein the carbon shell is a hollow carbon shell in the form of an empty space.
16. The composite nanoparticle according to claim 15, wherein the outer metal nanocrystals or the inner metal nanocrystals are at least one metal selected from the group consisting of platinum, palladium, rhodium, and iridium.
The composite nanoparticle according to claim 15 or 16, wherein the metal nanocrystals have a diameter of 1.4 to 3.4 nm.
16. The composite nanoparticle according to claim 15, wherein the carbon shell has a thickness of 5 to 10 nm.
16. The composite nanoparticle of claim 15, having a diameter of from 20 to 50 nm.
An electrode for a battery comprising a composite nanoparticle prepared by the method according to claim 1 and containing external metal nanocrystals having a diameter of 0.5 to 5 nm formed on the outer surface of the carbon shell.
The battery electrode according to claim 23, wherein the composite nanoparticle further comprises an inner metal nanocrystal having a diameter of 0.5 to 5 nm formed on an inner peripheral surface of the carbon shell.
24. A battery electrode according to claim 23, wherein the carbon shell is a hollow carbon shell in the form of an empty space inside.
24. The electrode for a battery according to claim 23, wherein the outer metal nanocrystals or the inner metal nanocrystals are at least one metal selected from the group consisting of platinum, palladium, rhodium, and iridium.

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