KR101580410B1 - Platinum-nikel alloy core-shell nanopaticles and making method thereof - Google Patents

Abstract

The method of the present invention comprises: a first step for mixing a capping agent, oleic acid, 1-octadecene, and oleylamine under a nitrogen atmosphere to make a capping solution; a second step for mixing platinum acetylacetonate, nickel acetylacetonate 1-octadecene, and oleylamine to manufacture a metallic salt solution; a third step for mixing the capping solution and the metallic salt solution to manufacture a mixed solution; and, a fourth step for performing a pyrolytic reaction to form a nanoparticle with a core-shell structure, to rapidly cool it down, and to obtain a nanoparticle. The specific surface area of a resin phase nanocatalyst is increased more greatly than that of a conventional nanoparticle of the same size, and the activated area of the catalyst is increased. As well, an electrode having higher oxygen reduction ability than when only platinum is used can be manufactured.

Description

Platinum-nickel alloy core-shell nanoparticles and method for manufacturing the same

The present invention relates to a nanoparticle for use in a catalyst such as a fuel cell, and more particularly, to a platinum-nickel alloy core-shell nanoparticle having a controlled nanostructure and a method for manufacturing the same.

Nanoparticles have received widespread attention because of their specific electrochemical, photochemical, biochemical sensors and catalytic properties. Shape controlled noble metal nanoparticles can be classified into two types: nano-structures (cube, octahedron, truncated cube, and tetrahedron, etc.), 1-dimensional nanostructures (nanowire, nanorod, Structures (nanoplate and nanosheet, etc.), and three-dimensional nanostructures (nanostar, nanoflower, etc.) have been studied.

On the other hand, the nanoparticle catalyst used as the redox electrode in the fuel cell has the greatest influence on the performance of the oxidation reaction, and the redox reaction occurring in the air electrode has a complicated mechanism and the reaction rate is considerably slow, Which is the main cause of the decrease. In order to increase the efficiency of the redox reaction, an alloy catalyst such as Pt-Co, Pt-Cu, Pt-Co-Cu and Pt-Pd using Pt or Co or Pd together or Pd @ Pt, Au @ Pt, PdNi @ Studies have been actively made on alloy catalysts of core-shell structures such as Pt and Ni @ Pt, and hollow catalysts.

Korean Patent Laid-Open Publication No. 2009-0049613 discloses a catalyst particle having a core particle diameter of core particles (core + shell) ranging from 20 to 100 nm, preferably 20 to 50 nm, as core-shell type catalyst particles. In particular, catalyst particles containing Pt-based shells exhibit high specific activity. The present invention discloses a method for manufacturing a catalyst particle containing a Pt-based shell by adjusting a thickness of an outer particle shell, wherein a noble metal Pt can be contained in an inner particle core. And a method for producing nanoparticles of a core shell structure containing platinum-nickel differing in the composition ratio of the shell have not been disclosed at all.

The present invention relates to a platinum catalyst which is mainly used as a catalyst for a fuel cell, and exhibits a low oxygen reducing power when only platinum is used, thereby increasing the activity of the oxygen reduction reaction by changing the structure of the nanoparticles, The core-shell nanoparticles are produced through a one-pot process.

The present invention provides a platinum-nickel alloy core shell catalyst comprising a support and core-shell nanoparticles supported on the support, wherein the core-shell nanoparticle comprises 81 to 84 wt% platinum and 16 to 19 wt% Nickel core shell nanoparticles consisting of a core comprising nickel of 66 to 72 weight percent platinum and a nickel shell of 28 to 34 weight percent nickel.

According to another aspect of the present invention, there is provided a process for preparing a capping solution by mixing a capping agent, oleic acid, 1-octadecene and oleylamine under a nitrogen atmosphere, (First step); Preparing a metal salt solution by mixing platinum acetylacetonate, nickel acetylacetonate, 1-octadecene and oleylamine (second step); Mixing 35 vol% of the metal salt solution with 65 vol% of the capping solution to prepare a mixed solution (third step); And a step of subjecting the mixed solution to thermal decomposition to form core-shell nanoparticles and then quenching again to obtain nanoparticles (step 4).

The capping agent is cetyltrimethyl-ammonium chloride, and may be added to the capping solution at 5 to 24% by volume.

The metal salt solution may have a platinum acetylacetonate concentration of 4.3 to 4.5 mM and a nickel acetonate concentration of 5.0 to 5.2 mM.

The fourth step may pyrolyse at 250 DEG C for 10 to 180 minutes.

The platinum-nickel alloy core shell nanoparticles may also comprise a shell comprising 81-84 wt% platinum and 16-19 wt% nickel, 66-72 wt% platinum and 28-34 wt% nickel, .

According to the method for producing a platinum-nickel alloy core-shell nanoparticle according to the present invention, it is possible to prepare dendritic core-shell nanoparticles having platinum rich in the core and controlled in the shape of nanoparticles containing platinum-nickel alloy in the shell . Since the dendritic nanocatalyst has a larger specific surface area than conventional nanoparticles of the same size, the active site of the catalyst is increased, and an electrode having an oxygen reduction ability higher than that of platinum alone can be produced. In addition, the pyrolysis process in which the metal salt solution and the mixed solution are separately prepared and injected at a high temperature can produce the core-shell nanoparticles produced by the conventional processes of at least two steps, do.

1 shows an XRD pattern of a platinum-nickel alloy core shell nanoparticle according to an embodiment of the present invention.
2 is an FE-TEM and HR-TEM image of a platinum-nickel alloy core shell nanoparticle according to an embodiment of the present invention.
Figure 3 illustrates EDX analysis of platinum-nickel alloy core shell nanoparticles according to one embodiment of the present invention.
FIG. 4 shows an EDX analysis of platinum-nickel alloy core shell nanoparticles according to an embodiment of the present invention with addition of 120 mM CTAC.
Figure 5 shows the XRD pattern of platinum-nickel alloy core shell nanoparticles according to one embodiment of the present invention.
6 is a CV curve measured by cyclic voltammetry (CV) of a catalyst comprising platinum-nickel alloy core-shell nanoparticles according to an embodiment of the present invention.
Figure 7 is a constant potential scan curve of a catalyst comprising platinum-nickel alloy core shell nanoparticles according to one embodiment of the present invention.
8 is a graph comparing the oxygen reduction activity of a catalyst comprising platinum-nickel alloy core-shell nanoparticles according to an embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the drawings.

The present invention provides a platinum-nickel alloy core shell catalyst comprising a support and core-shell nanoparticles supported on the support, wherein the core-shell nanoparticle comprises 81 to 84 wt% platinum and 16 to 19 wt% Nickel core shell nanoparticles consisting of a core comprising nickel of 66 to 72 weight percent platinum and a nickel shell of 28 to 34 weight percent nickel.

As the precursor for forming the core and the shell, platinum may be selected from platinum acetylacetonate (Pt (acac) ₂ ), and nickel may be selected from acetylacetonate ((Ni (acac) ₂ ).

The core may contain platinum in an amount of 81 to 84 wt%, and the shell may contain 66 to 72 wt% of platinum and 28 to 34 wt% of nickel in an alloy form.

When the above conditions are exceeded, core shell structure nanoparticles having different composition ratios of the core and shell can not be formed, and the oxygen reduction activity of the prepared core shell structure nanoparticles is not increased.

According to another aspect of the present invention, there is provided a capping composition comprising a capping agent, oleic acid, 1-octadecene and oleylamine in a nitrogen atmosphere, A manufacturing step (first step); Preparing a metal salt solution by mixing platinum acetylacetonate, nickel acetylacetonate, 1-octadecene and oleylamine (second step); Mixing the metal salt solution with the capping solution to prepare a mixed solution (step 3); And a step of subjecting the mixed solution to thermal decomposition to form core-shell nanoparticles and then quenching again to obtain nanoparticles (step 4).

When the components added in the first step are different, the metal salt solution can not be prepared even when platinum acetylacetonate or nickel acetylacetonate is added.

The capping agent is cetyltrimethyl-ammonium chloride (CATC) and may be added to the capping solution at 5 to 24 vol%.

The capping agent can supply chlorine atoms as a halogen agonist. When the chlorine atoms can not be supplied, the core shell nanoparticles having different composition ratios of platinum and nickel contained in the core and the shell can not be prepared. The critical concentration of CTAC for preparing platinum-nickel alloy core shell nanoparticles can not be met.

The chlorine atoms of the CTAC can form two platinum complexes ( P t ^{2 +} = 1.18 V PtCl ^{x y-} = 0.68 V) having different reduction potentials due to the bonding with platinum, and due to the reduction rate of two different platinum It is possible to produce nanoparticles having an inner and outer composition different from each other, a single particle of an alloy, and a core shell structure.

The platinum acetylacetonate and nickel acetylacetonate are precursors for producing a metal salt, and a metal salt solution can be prepared by mixing 1-octadecene and oleylamine, The concentration of acetylacetonate may be 4.0 to 4.5 mM and the concentration of nickel acetonate may be 1.0 to 1.5 mM.

In the step of preparing the mixed solution, it is possible to mix 35 vol% of the metal salt solution with respect to 65 vol% of the capping solution. When the concentration exceeds the above range, the concentration of the CTAC contained in the capping solution becomes too low, Particles can not be produced.

In addition, when the above conditions are exceeded, the metal salt solution is not formed, and the core shell nanoparticles are not formed in a dendritic state during the following pyrolysis reaction.

On the other hand, if the step of preparing the capping solution and the step of preparing the metal salt solution are not separately performed, rapid nucleation of platinum and nickel can not be induced and the entire reaction time can not be shortened in a pyrolysis reaction.

In the fourth step, the mixed solution may be subjected to a thermal decomposition reaction at 250 ° C for 100 to 180 minutes. When the reaction conditions are out of the above range, it is impossible to induce nucleation by the one-pot process, and the shell can not have a platinum-nickel alloy structure.

 The mixed solution in which the nanoparticles are formed after the pyrolysis reaction can be quenched, and the thermodynamically unstable structure can be maintained when quenching is performed.

The platinum-nickel alloy core shell nanoparticles may also comprise a core comprising 81-84 wt.% Platinum and 16-19 wt.% Nickel, 66-72 wt.% Platinum and 28-34 wt.% Nickel have.

The prepared platinum-nickel alloy core-shell nanoparticles can produce nanoparticles in which the core contains abundant platinum and the shell contains platinum-nickel alloy and the composition ratio of the core and the shell is different.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited to the following examples.

< Example  1> Platinum-nickel alloy Core shell  Nanoparticle manufacturing

 10 ml of 1-octadecene (90%, Aldrich), 2 ml of oleic acid, and 60 mM cetyltrimethyl-ammonium chloride (hereinafter referred to as &quot; 'CTAC') were mixed to prepare a capping solution (Step 1).

0.044 g of platinum acetylacetonate (97%, Aldrich) and 0.035 g of nickel acetylacetonate (95%, Aldrich) were mixed with 5 ml of 1-octadecene as a metal precursor, 4 ml of oleylamine was added thereto to prepare a metal salt solution (second step).

The metal salt solution was added to the capping solution and subjected to a thermal decomposition reaction at 250 ° C for 180 minutes to prepare a colloidal solution mixture solution (Step 3).

The mixed solution was poured into 100 mL of n-hexane (95%, SAMCHUN), quenched, and washed several times with ethanol (95%, SAMCHUN) in a centrifuge to obtain nanoparticles as a resultant product Step 4).

In order to remove residues such as surfactants from the nanoparticles, the suspension was added to 30 mL of acetic acid (99.7%, SAMCHUN) and carried at 80 DEG C for 12 hours, washed several times with ethanol and dried to obtain a final product, platinum- Alloy core shell nanoparticles.

< Example  2> Capping agent  Concentration change

A sample was prepared by changing the capping agent CTAC added to the pyrolysis process of Example 1 from 90 to 120 mM. The reaction conditions were carried out at 250 DEG C for 180 minutes.

< Example  3> reaction time change

A sample was prepared by changing the thermal decomposition time of Example 1. The capping agent CTAC was adjusted to 60 mM at 250 &lt; 0 &gt; C for 10 to 60 minutes.

< Example  4> Adding chlorine to form nanoparticles

In the formation of nanoparticles, 0.5 M HCl was used as a halogen source instead of the capping agent CTAC in order to confirm the effect of chlorine, which is a halogen agent, and the reaction conditions were carried out at 250 ° C. for 180 minutes.

< Example  5> Core shell  Addition of metal salts in the generation of nanoparticles

Pure platinum nanoparticles were prepared in the same thermal decomposition reaction procedure as in Example 1 in the presence of CTAC except for the nickel salt. The metal salt solution contained 0.0442 g of platinum acetylacetonate (97%, Aldrich) and 0.035 g of nickel acetylacetonate (97%, alfrich) as metal precursors and 1-octadecene 5 ml of oleylamine and 4 ml of oleylamine.

< Example  6> Preparation of catalyst for oxygen reduction electrode

Nickel alloy core-shell nanoparticles prepared in Example 1 were used as a catalyst and a binder (Nafion perfluorinated resin solition, Aldrich) was used as a catalyst to confirm the effect of the prepared platinum-nickel alloy core- , And a dispersant (2-propanol, Aldrich) were coated on a glacier carbon electrode as a working electrode. A platinum rod electrode was selected as a counter electrode and a silver / silver chloride electrode was selected as a reference electrode. The electrochemical active area (EASA, electrochemically active area) of the catalyst was determined by measuring the cyclic voltametry (CV) under the condition of perchloric acid under the argon saturation with a scan rate of 50 mV / s through a configured half cell system. surface area) were measured.

Oxygen reduction was also confirmed by linear sweep voltametry (LSV) at 5 mV / s scan rate, 1600 rpm, oxygen saturation and perchloric acid.

< Experimental Example  1> Platinum-nickel alloy Core shell  Properties of nanoparticles

In order to analyze the shape of the sample, a field-emission transmission electron microscope (FE-TEM) and a high-angle annular dark field (HAADF) equipped with a Tecnai G2 F30 system at 300 kV transmission electron microscopy). Energy dispersive X-ray (EDX) was performed on the FE-TEM, and the sample for the TEM sample was platinum-nickel dispersed in ethanol on a carbon-coated copper grid A TEM sample was prepared by adding a catalyst suspension to the alloy core shell nanoparticles.

X-ray diffraction (XRD) was performed with a Bruker D2 PHASE system and proceeded with Cu Kα (λ = 0.15406 nm) at 30 kV and 10 mA.

One. Capping agent  Platinum-nickel alloy according to concentration Core shell  Changes in composition of nanoparticles

The sample was prepared by pyrolysis at 250 DEG C for 180 minutes by varying the concentration of CTAC by the method prepared in Example 1.

1 shows an XRD pattern of a platinum-nickel alloy core shell nanoparticle according to an embodiment of the present invention.

Fig. 1 (a) shows a wide-angle XRD pattern, Fig. 2 (b) shows a pattern of narrow-angle XRD, and the bars of red and blue correspond to the reference peaks of platinum and nickel.

Referring to the drawings, the measured data were compared with the reference data of platinum (JCPDS No. 04-0802) and the reference data of nickel (JCDPDS No. 04-0850). In pure platinum, the XRD peaks corresponded to (111), (200) and (220) at 39.67, 46.15 and 67.48, respectively, indicating a face-centered cubic (fcc).

The addition of CTAC-free samples and 30 mM CTAC showed a higher XRD peak shift at 2θ values compared to typical platinum amorphous structures. When considered as a substitutional solid solution between platinum and nickel, the higher angular movements of the diffraction peak position represented a single platinum phase rich between the metal phases. And as the concentration of CTAC increased from 60 to 120 mM, the product was found to have overlapping XRD peaks associated with platinum-based alloy phases in the entire diffraction range. In particular, the peak at (200) of the product was clearly separated into two peaks and included two platinum-nickel alloy phases when produced at a relatively low CTAC content or at a relatively high CTAC content compared to no CTAC added .

2 is an FE-TEM and HR-TEM image of a platinum-nickel alloy core shell nanoparticle according to an embodiment of the present invention.

60 mM of CTAC was added and pyrolyzed and synthesized at 250 DEG C for 180 minutes to prepare platinum-nickel alloy core shell nanoparticles.

FIG. 2 (a) is an FE-TEM image of a platinum-nickel alloy core shell nanoparticle, FIG. 2 (b) is an HR-TEM image of a platinum-nickel alloy core shell nanoparticle, Of a platinum-nickel alloy core shell nanoparticle XRD pattern having a platinum-rich core and a shell comprising platinum and nickel produced by adding CTAC at 250 &lt; 0 &gt; C for 180 minutes and FIG. 2 2 (h) and 2 (i) show the mapping profile and HAADF-STEM image of a single platinum-nickel alloy core shell nanoparticle element, Lt; / RTI &gt;

Referring to the figures, the platinum-nickel alloy core shell nanoparticles have a very dark contrast at the center of the nanodendrites, indicating that the platinum-nickel alloy core shell nanoparticles are three-dimensional in structure. As shown in FIG. 2 (c), the XRD peak of the platinum-nickel alloy core shell nanoparticles was clearly fit by the two peaks.

[Formula 1]

d _{Pt - Ni} = xd _Pt + (1-x) d _Ni

According to the criteria of the Baeguard rule shown in the above formula 1, the diffraction peaks of A and B of platinum: nickel atomic ratios were observed at 94: 6 and 74:26, respectively. XRD analysis showed that the platinum-nickel nanoparticles had two phases with distinct compositions of platinum and nickel. The HAADF-STEM image and the element mapping image of the single nanoparticles were observed and shown in FIGS. 2 (d) to 2 (g). The platinum and element mapping obtained by HAADF-STEM-EDX indicated that the platinum-nickel alloy core shell nanoparticles had two different platinum: nickel ratios on the inner and outer regions, respectively. 2 (h) and 2 (i), the point EDX analysis of single nanoparticles revealed that platinum: nickel was present in the inner and outer regions, respectively, as (96: 4) and (71: 29).

The EDX data showed that the platinum-nickel nanoparticles were in two distinct phases with different platinum and nickel elemental compositions, which agreed well with the XRD analysis.

HAADF-STEM and EDX analysis of platinum-nickel alloy core-shell nanoparticles prepared in the presence of 90 and 120 mM CTAC for 180 min at 250 ^° C. When 90 mM CTAC was added, the XRD diffraction peaks of A and B were measured at 88:12 and 64:36, respectively, to confirm the atomic ratio of platinum: nickel.

Figure 3 illustrates EDX analysis of platinum-nickel alloy core shell nanoparticles according to one embodiment of the present invention. 3 (a) shows XRD patterns of nanoparticles of a platinum-rich core and a platinum-nickel alloy shell structure obtained by adding 90 mM CTAC and reacting at 250 ° C for 180 minutes, and FIGS. 3 (b) 3 (f) and 3 (g) show the HAADF-STEM image and element mapping profile of a single platinum-nickel alloy core shell nanoparticle, EDX spectrum.

As a result of the EDX measurement, the atomic composition of platinum: nickel corresponding to the inside and outside of the shell was (84:16) and (66:34) in the inside and outside areas, respectively. Figure 4 shows an EDX analysis of platinum-nickel alloy core shell nanoparticles according to one embodiment of the present invention. 4 (a) shows XRD patterns of nanoparticles of a platinum-rich core and a platinum-nickel shell structure added with 120 mM CTAC and reacted at 250 ° C for 180 minutes, and FIGS. 4 (b) FIG. 4 (f) and FIG. 4 (g) show the HAADF-STEM image and element mapping profile of a single platinum-nickel alloy core shell nanoparticle and the EDX of the core and shell of the platinum- Lt; / RTI &gt;

Referring to the figure, when the reaction was carried out by adding 120 mM of CTAC, the atomic ratios of platinum and nickel were found to be 87:13 and 73:27, respectively. As a result of the EDX measurement, the compositions of elements of platinum and nickel corresponding to the inside and outside Were 81: 19 and 71: 28, respectively.

 Comparing XRD and EDX data, it was confirmed that the prepared nanoparticles were encapsulated with a platinum-nickel alloy shell with a platinum-rich core and could be produced in a one-pot process at high CTAC concentrations.

The dendritic platinum-nickel alloy core-shell nanoparticles may have a relatively increased specific surface area as compared to spherical nanoparticles of the same size, thereby greatly increasing the active area.

2 . Change of Composition of Platinum-Nickel Alloy Core Shell Nanoparticles by Reaction Time

In order to confirm the growth of platinum-nickel alloy core shell nanoparticles including a platinum-rich core and a shell containing platinum and nickel according to the reaction time, 60 mM of CTAC was added at 250 ° C., Respectively. The XRD patterns of the nanoparticles grown for 10 to 60 minutes showed a slightly higher angular shift of the diffraction peaks as compared to the polycrystalline platinum having the body-centered cubic structure.

Figure 5 shows the XRD pattern of platinum-nickel alloy core shell nanoparticles according to one embodiment of the present invention. 5 (a) shows the XRD pattern at the wide angle of the nanoparticles prepared by adding 60 mM CTAC and the pyrolysis reaction time at 250 ° C, and FIG. 5 (b) shows the XRD pattern at the narrow angle . The red and blue bars correspond to the reference peaks of platinum and nickel.

 Referring to the drawings, there was shown a single platinum-rich phase having an average composition of platinum: nickel of 93: 7, followed by growth for 100 minutes, and XRD analysis of platinum-nickel alloy core shell nanoparticles revealed platinum and nickel Lt; RTI ID = 0.0 &gt; 2 &lt; / RTI &gt; The atomic ratios of platinum and nickel identified on the left and right sides of the diffraction peaks were 92: 8 and 74: 26, respectively.

After 180 minutes of growth, the platinum-nickel alloy core-shell nanoparticles exhibited two platinum-based phases corresponding to A and B with platinum: nickel of 94: 6 and 72: 28, respectively. As the reaction time increased, the XRD peak corresponding to B was enhanced during the increase of the particle size and confirmed through the TEM image of FIG. This indicates that the platinum-nickel alloy phase grows after the platinum-rich phase first grows.

3. Change of particle composition with presence of chlorine

In order to confirm the effect of chlorine as a halogen agonist in platinum-nickel alloy core shell nanoparticles, 0.5 M HCl was used instead of CTAC as a halogen source and pyrolyzed at 250 ° C for 180 minutes.

As a result of XRD pattern analysis of the prepared nanoparticles, the atomic ratios of platinum: nickel corresponding to the diffraction peaks of A and B were determined to be 93: 7 and 84: 16, respectively. XRD analysis showed that the platinum-nickel nanoparticles had a platinum-nickel alloy phase with two distinct compositions of platinum and nickel.

Analysis of the HAADF-STEM and elemental mapping images of a single platinum-nickel alloy core shell nanoparticle showed that the nanoparticles had two different platinum: nickel ratios in the core and shell portions, and the EDX analysis showed that platinum: nickel Were found to have two different ratios of 92: 8 and 85: 15.

Compared to XRD and EDX, the nanoparticles prepared by adding HCl were found to have a platinum-rich core and a shell of an alloy of platinum-nickel, which is a platinum-nickel alloy prepared by adding CTAC under the same conditions Core shell nanoparticles. The results show that cetyltrimethyl-ammonium chloride and hydrochloric acid play an important role in the formation of platinum-nickel alloy core-shell nanoparticles.

The reduction process of [PtCl _x ] ^y- / Pt ^o (~ 0.7 V vs. SHE) under CTAC atmosphere may be accompanied by Pt ^{2 +} / Pt ^o (1.18 V vs. SHE) Pt nanoparticles could be formed by the reduction process of Pt ^{2 +} / Pt ⁰ with relatively high reduction potential. On the other hand, a completely different reduction process of Pt ^{2 +} / Pt ⁰ and [PtCl _x ] ^y- / Pt ⁰ at relatively high CTAC concentrations showed two platinum-nickel alloy phases in platinum-nickel nanoparticles. In the initial stage of the pyrolysis process, platinum nucleation occurred predominantly in the core of the nanoparticles, and as a result, the platinum-rich nanoparticles produced by the catalytic reaction induce the reduction of nickel to produce [PtCl _x ] ^{y -} / ^o platinum Pt through the reduction of process-nickel alloy shell to form. Considering the concentration of CTAC and the reaction time, it was confirmed that the reaction time of 100 minutes or more and the CTAC concentration of 60 mM or more were critical conditions in the preparation of platinum-nickel alloy core shell nanoparticles composed of a platinum-rich core and a platinum- Pt in the ^{+ 2,} the standard reduction potential of Pt ^o (1.18 V vs. SHE) from the Ni ^{2 +} Ni ^o is extremely higher than the standard reduction potential (-0.257 V vs. SHE) is formed of platinum than the nucleus formation of nickel nuclei More voluntary. Platinum-nickel alloy core shell nanoparticles prepared through the one-pot process have platinum-rich cores and a shell of platinum-nickel alloy. In the initial stage of the pyrolysis reaction, platinum- And platinum-rich nanoparticles formed catalyzed the reduction of nickel to form a platinum-nickel alloy in the shell of nanoparticles.

4. Core shell  Effect of metal salts on the formation of nanoparticles

In order to confirm the easier reduction method of Ni ^{2 +} to Ni ⁰ in the presence of platinum nanoparticles, 60 mM CTAC was added and pyrolyzed at 250 ^° C for 100 min to prepare platinum nanoparticles (Pt (acac) ₂ ) was added with a nickel salt solution mixed with 1-octadecene and oleylamine to prepare a platinum nanoparticle colloid solution. For comparison, platinum nanoparticles were excluded and a nickel salt solution was prepared under the same synthesis conditions. The XRD pattern was analyzed to show that no nickel metal phase (Ni ⁰ ) was formed without the presence of platinum nanoparticles, and the corresponding XRD peak on the platinum-nickel alloy phase was platinum nanoparticles that accelerated the reduction from Ni ²⁺ to Ni ⁰ In the presence of nickel.

5. Oxygen reduction effect of catalyst

FIG. 6 is a CV curve measured by cyclic voltammetry (CV) of a catalyst containing platinum-nickel alloy core-shell nanoparticles according to an embodiment of the present invention, and FIG. FIG. 8 is a graph comparing the oxygen reduction activity of a catalyst comprising platinum-nickel alloy core-shell nanoparticles according to an embodiment of the present invention. FIG. It is a graph.

In the oxygen reduction reaction, the reduction starting voltage and the halfwave potential were improved as compared with the pure platinum catalyst. As the platinum and nickel became alloys, the D-band center was lowered, The oxygen reduction reaction was more easily induced than the pure platinum catalyst by lowering the energy absorbed on the surface of the catalyst.

As described above, according to the present invention, platinum-nickel alloy core shell nanoparticles were prepared by one-pot pyrolysis process by controlling the reaction time in the presence of CTAC. In the initial stage of pyrolysis reaction, It was confirmed that the shell had a platinum-rich core and a shell made of a platinum-nickel alloy. The catalysts prepared by carrying out the prepared platinum - nickel alloy core shell nanoparticles showed much higher reduction starting voltage and halfwave potential than the pure platinum catalyst, and the activity of the oxygen reduction reaction was greatly increased.

While the invention has been described with reference to a limited number of embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (6)

delete Preparing a capping solution by mixing a capping agent, oleic acid, 1-octadecene and oleylamine under a nitrogen atmosphere (first step);
Preparing a metal salt solution by mixing platinum acetylacetonate, nickel acetylacetonate, 1-octadecene and oleylamine (second step);
Mixing the capping solution and the metal salt solution to prepare a mixed solution (Step 3); And
(C) decomposing the mixed solution at 250 ° C for 100 to 180 minutes to form core-shell nanoparticles and quenching again to obtain nanoparticles (Step 4)
The capping agent is cetyltrimethyl-ammonium chloride, added to the capping solution in an amount of 5 to 24% by volume,
Wherein the metal salt solution has a platinum acetylacetonate concentration of 4.0 to 4.5 mM, a nickel acetonate concentration of 1.0 to 1.5 mM,
The nanoparticles of the core shell structure comprise a core comprising 81-84 wt% platinum and 16-19 wt% nickel, a platinum-nickel alloy comprising 66-72 wt% platinum and 28-34 wt% nickel A method for manufacturing core shell nanoparticles.
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