KR101591640B1 - Core containing platinum nanodots assemblies and silica shell nanoparticles and synthetic method thereof - Google Patents

Abstract

Platinum (Pt) nanodots assembly (m-Pt) core-silica shell nanosystems {m-Pt@SiO_2 NPs (spherical nanoparticles) and m-Pt@SiO_2 NChs (nanochains)} are synthesized by a reverse microemulsion (water-in-oil) based method. The morphologies and structural properties of the core-shell nanoparticles are controlled and characterized by means of the transmission electron microscopy (TEM) and the scanning electron microscopy (SEM). Platinum/gold nanodots assembly (m-Au/Pt) core-silica shell nanosystems (m-Au/Pt@SiO_2NPs) are synthesized. Hybridized multiple metal core-silica shell systems are formed by reduction of HAuCl_4 and K_2PtCl_4, dynamically controlled by a surfactant Brij35, and condensation of TEOS in the reverse micelle. The nanoparticles and the nanochains of the present invention can be applied as an effective catalyst or an energy transferring material.

Description

[0001] The present invention relates to nanoparticles formed from a core containing a platinum nano-dot combination and a nanoparticle formed out of silica, and a method for synthesizing the nanoparticles and silica shell nanoparticles.

The present invention relates to a core comprising a platinum nano-dot combination of a single composition or a nano-dot combination of a platinum / gold double composition, nanoparticles formed in a silica outer shape, and a method of synthesizing the same.

Over the last 20 years, many scientific and technical interests have been attracted to nanoparticle assembly studies (Saunders, AE; Korgel, BA ChemPhysChem 2005 , 6 , 61. (b) Redl, FX; Cho, K.-S .; Murray , CB;.. O'Brien, S. Nature 2003, 423, 968. (c) Rogach, AL Angew Chem Int Ed 2004, 43, 148. (d) Kalsin, AM;.. Fialkowski M .; Paszewski, M Russell, TP; Rotello, R., et al., J. Biol., ≪ RTI ID = 0.0 > Smoukov, < / RTI >SK; Bishop, KJM; Grzybowski, BA Science , 2006 , VM Nature , 2000 , 404 , 746. (f) Andres, RP; Bielefeld, JD; Janes, DB; Kolagunta, VR; Kubiak, CP; Mahoney, WJ; Osifchin, RG Science , 1996 , 273 , 1690 (i) Brust, JL Nature, 1996 , 382 , 607. (g) Giersig, M. Mulvaney, P. Langmuir 1993 , 9 , 3408. (h) Mirkin, CA; Letsinger, RL; Mucic, M .; Schiffrin, DJ; Bethell, D .; Kiely, C. J. Adv Mater 1995, 7, 795. (j) Murray, CB;.. Kagan, CR; Bawendi, MG Science 1995, 270, 1335.) . The chemical and physical properties of nanoparticle assemblies are highly dependent on the constituent and structural properties of the nanoparticles and, most of all, on the manner in which the nanoparticles are distributed. The overall properties that individual nanoparticles can represent as a combination are greatly influenced by the distance, arrangement type and interaction between the nanoparticles as a basic element (Petroski, JM; Green, TC; El-Sayed MA, J. Phys . Chem . A , 2001 , 105, No. 23, 5542.). Understanding that size and distribution are related to this type of system change, new materials can be developed with new technologies. Have used the interesting properties of nanoparticles in other technologies such as optoelectronics, diagnostics, catalysts and medical fields ((a) Maier, SA; Kik, PG; Atwater, HA; Meltzer, , BE; Requicha, AAG Nat . Mater . 2003 , 2 , 229. (b) Hoinville, J .; Bewick, A .; Gleeson, D .; Jones, R .; Kasyutich, O .; Mayes, , A .; Warne, B .; Wiggins , J .; Wong, K. J. Appl Phys 2003, 93, 7187. (c) Grunes, J .; Zhu, J .; Anderson, EA;.. Somorjai, GA . J. Phys Chem B 2002, 106 , 11463. (d) Zayats, M .; Kharitonov, AB;. Pogorelova, SP;.. Lioubashevski, O .; Katz, E .; Willner, I. J. Am Chem Soc 2003, 125, 16006.).

Recently, a convenient synthesis method of highly spherical nanoparticles composed of a gold nanodet combination and a silica outer shell was developed by the present inventors' team (9). A gold nanodot with a grain size of 2-5 nm surrounded by silica using reverse microemulsion (water of oil) was successfully synthesized by a controllable method. The silica shell can be further etched with a simple treatment in a water-soluble solvent to produce gold nanodot core-porous silica nanoparticles (10). This is a new and simple synthesis method for preparing functional hybrid gold-silica nanomaterials by wrapping a gold nanoparticle combination in a silica matrix.

Platinum-based nanoparticle assemblies have been highly emphasized due to their ability to enhance the unique properties of pure platinum nanomaterials (11-18). It is also known that some of the properties of metal nanoparticles are significantly affected when other nanoparticles such as platinum, gold, and silver are in close proximity (19-21). Therefore, there is a growing interest in research into the effective combination of single component platinum nanoparticles and multi-component platinum and gold nanoparticles. In addition, surrounding materials such as silica can improve the stability of platinum nanoparticles. The outer shell isolates the catalytically active nanoparticle core and inhibits the sinterability of the core particles during the catalytic reaction at high temperatures. The synergistic effect of metal-support interface appears to be maximized when such interface is important in the performance of catalysis (13).

9. Pak, J .; Yoo, H. J. Mater. Chem. A. 2013, 1, 5408. 10. Pak J .; Yoo, H. Microporous Mesoporous Mat. 2014, 185, 107. 11. Ingle, N.J.C .; Sode, A .; Martens, I. Langmuir 2014, 30, 1871. 12. Cho, J. H .; Kim, J. M .; Prabhuram, J .; Hwang, S. Y .; Ahn, D. J .; Ha, H. Y .; Kim, S.-K. J. Power Sources 2009, 187, 378. 13. Song, Y .; Garcia, R .; Dorin, R .; Wang, H .; Qiu, Y .; Coker, E .; Steen, W .; Miller, J .; Shelnutt, J. Nano Lett. 2007, 7, 3650. 14. Xia, Y .; Xiong, Y .; Lim, B .; Skrabalak, S. Angew. Chem. 2009, 48, 60. 15. Xia, B. Y .; Wu, H. B .; Yan, Y .; Lou, X. W. D .; Wang, X. J. Am. Chem. Soc. 2013, 135, 9480. 16. Zhang, W .; Yang, S. Acc. Chem. Res. 2009, 42, 1617. 17. Chen, J .; Cheng, F. Acc. Chem. Res. 2009, 42, 713. 18. Guo, S .; Wang, E. Acc. Chem. Res. 2011, 44, 491. 19. Huang, H. Y .; Chen, W. F .; Kuo, P. L. J. Phys. Chem. B 2005,109, 24288. 20. Hu, H .; Duan, H .; Yang, J. K. W .; Shen, Z. X. ACS Nano 2012, 6, 10147. 21. Osberg, K. D .; Rycenga, M., Harris, N .; Schmucker, A. L .; Langille, M. R .; Schatz, G. C .; Mirkin, C. A. Nano Lett. 2012, 12, 3828. 22. Zhang, Q .; Lee,; Joo, J. B .; Zaera, F .; Yin, Y. Acc. Chem. Res. 2013, 46, 1816. 23. Yoo, H .; Sharma, J .; Kim, J. K .; Shreve, A.P .; Martinez, J. S. Adv. Mater. 2011, 23, 4431. 24. Jang, M. H.; Kim, J. K .; Tak, H .; Yoo, H. J. Mater. Chem. 2011, 21, 17606. 25. Jang, M. H.; Kim, J. K .; Yoo, H. Journal of Nanoscience and Nanotechnology 2012, 12, 4088. 26. Yoo, H .; Pak, J. J. Nanopart. Res. 2013, 15, 1609. 27. Han, Y .; Wang, Y .; Wang, Y .; Jiao, L .; Yuan, H. International Journal of hydrogen energy 2010,35, 8177.

The present invention aims at providing spherical nanoparticles of silica outer shell containing several platinum nanodate combinations in a simple process and a method of synthesizing the same.

It is another object of the present invention to provide silica outer nanoparticles containing a nano dot combination core of a platinum / gold double composition and a method of synthesizing the same.

It is another object of the present invention to provide a one-dimensional nanochain of silica outer shell containing several platinum nanodots and a method of synthesizing the one-dimensional nanochain.

We have found that platinum multi-nanodate combination (m-Pt) core-silica outer nano system (m-Pt @ SiO ₂ NPs (spherical nanoparticles) and m-Pt @ SiO2 NChs (nanochains)). Inverse microemulsion was used and gold nanoparticles and silica layer were grown simultaneously in the modified microemulsion. In addition, a nano-dot combination (m-Au / Pt) core-silica outer nano system (m-Au / Pt @ SiO2 NPs) with a platinum / gold double composition was also successfully synthesized. Reduction of kinetic controlled HAuCl4 and K2PtCl4 by Brij35 surfactant in reversed micelles and condensation of TEOS formed a hybrid multimetallic core-silica shell system.

In the present invention, "nanodot" is a term generally referred to as a "nanoparticle ", that is, a particle having a particle diameter of nanometer units. In particular, the nanoparticles arranged in the central portion of the silica particle, It also emphasizes the small size and also. The term "nanodot" was used to distinguish it from the spherical "nanoparticles" made of the multi-nanodot core of the present invention and the silica shell.

The present invention relates to a method for synthesizing platinum nanoparticles having a particle size of 3 to 5 nm by reducing the Pt ^{2 +} precursor exhibiting a relatively lower reducing power than the Au ^{3 +} precursor by using the nonionic surfactant without adding a special reducing agent will be.

The present invention also relates to a method for preparing a Pt ^{2 +} precursor having a relatively lower reducing power than an Au ^{3 +} precursor using a reversed microemulsion in which a platinum solution is implanted in a reversed micelle emulsion without adding a specific reducing agent to the nonionic surfactant To thereby synthesize platinum nanoparticles having an average particle diameter of 1 to 2 nm.

In addition,

a) mixing a nonionic surfactant and a nonpolar organic solvent to prepare a microemulsion;

b) adding a cationic platinum precursor-containing aqueous solution to the microemulsion and subjecting the microemulsion to ultrasonic treatment to produce a reversed microemulsion containing the platinum solution; And

c) synthesizing nanoparticles composed of polyplatinum nanodots core and silica by sequentially adding a silica precursor and a basic catalyst while stirring the reverse microemulsion containing the platinum solution and stirring the nanoparticles, The present invention relates to a method for synthesizing spherical nanoparticles made of silica.

In addition, the present invention is characterized in that after the step c)

d) destabilizing the microemulsion system by adding acetone to the reaction solution; And

e) c) repeating the washing and purification of the nanoparticles synthesized in step c), and then adding the nanoparticles to the nanoparticles.

The present invention also relates to a method for producing a polylactic acid composition, which is characterized in that the nonionic surfactant is polyoxyethylene glycol dodecyl ether, glycerin fatty acid ester, sucrose fatty acid ester or sorbitan fatty acid ester. To a method for synthesizing spherical nanoparticles.

The present invention also relates to a method for synthesizing spherical nanoparticles composed of polyplatinum nanodots core and silica, wherein the basic catalyst is an ammonia aqueous solution.

The present invention also provides a multi-platinum nano-dot core, characterized in that the silica precursor is at least one selected from tetraethyl orthosilicate, tetramethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl orthosilicate, tetrachlorosilane and sodium silicate. And a method for synthesizing spherical nanoparticles made of silica.

The present invention also relates to a method for synthesizing spherical nanoparticles composed of polyplatinum nanodots core and silica, which further comprises an auxiliary surfactant in step a).

The present invention also relates to a process for preparing a lithium _secondary battery, wherein the cationic platinum precursor in step b) is a platinum divalent transition metal compound (potassium tetrachloroplatinate (II), K ₂ PtCl _4, platinum (II) chloride, ₂ , PtBr ₂ , Wherein _{PtI 2, Platinum (II) acetylacetonate} , Dichloro (ethylenediamine) platinum (II), (acac) 2, potassium bis (oxalato) platinate (II) dihydrate K2Pt (C 2 O 4) 2 · 2H 2 O, etc.) To a method for synthesizing spherical nanoparticles composed of polyplatinum nanodots core and silica.

The present invention also relates to spherical nanoparticles synthesized by the above method and composed of a multi-platinum nanodot core and a silica outer shell in which a plurality of platinum nanodots are encapsulated in a silica outer shell.

In addition,

a) mixing a nonionic surfactant, a nonpolar organic solvent and HCl at a concentration of 1M to 12M to prepare a microemulsion;

b) adding a cationic platinum precursor-containing aqueous solution to the microemulsion and subjecting the microemulsion to ultrasonic treatment to produce a reversed microemulsion containing the platinum solution; And

c) synthesizing nanoparticles composed of polyplatinum nanodots core and silica by sequentially adding a silica precursor and a basic catalyst while stirring the reverse microemulsion containing the platinum solution and stirring the nanoparticles, Dimensional nanochain comprising a silica outer shell.

The present invention also relates to a one-dimensional nanochain prepared by the above method and consisting of a polyplatinum nanodot core and a silica outer shell.

In addition,

a) mixing a nonionic surfactant and a nonpolar organic solvent to prepare a microemulsion;

b) sequentially adding an aqueous solution containing a cationic platinum precursor, an aqueous solution containing ascorbic acid and a cationic gold precursor at a concentration of 0.1 M to 1 M to the microemulsion, and subjecting the microemulsion to ultrasonic treatment to prepare an inverted microemulsion containing the platinum and gold solution; And

c) synthesizing nanoparticles composed of a two-component multiple gold / platinum nano-dot core and a silica matrix by sequentially adding a silica precursor and a basic catalyst while stirring the reverse microemulsion, and stirring the mixture, The present invention relates to a method for synthesizing spherical nanoparticles composed of a dent core and a silica outer shell.

The present invention also relates to a method for preparing a gold-based gold-based gold-based gold-based gold-based gold alloy, wherein the cationic gold precursor in step b) is selected from the group consisting of potassium chloride (KAuCl ₄ ), sodium chloride (NaAuCl ₄ ), sodium chloride (HAuCl ₄ ), sodium bromate (NaAuBr ₄ ) Platinum nano-dots core and silica spherical nanoparticles, characterized in that the gold nanoparticles are selected from the group consisting of gold (III) chloride (AuCl ₃ ) and gold bromide (AuBr ₃ ).

In addition, the present invention step b) platinum divalent transition metal compound in Step is titanium tetrachloride acid (Ⅱ), potassium (potassium tetrachloroplatinate (II), K 2 PtCl 4, platinum (II) chloride, a halogenated platinum PtCl _2, PtBr ₂ , Selected from _{PtI 2, Platinum (II) acetylacetonate} , Dichloro (ethylenediamine) platinum (II), (acac) 2, potassium bis (oxalato) platinate (II) dihydrate K2Pt (C 2 O 4) 2 · 2H 2 O, etc.) The present invention relates to a method for synthesizing spherical nanoparticles composed of a two-component multiple gold / platinum nano-dot core and a silica shell.

The present invention also relates to spherical nanoparticles composed of a gold / platinum dual composition combination nano dots core and silica outer shell, which are synthesized by the above method and contain a plurality of gold nanodots and platinum nanodots in a silica outer shell.

In general, when metallic nanoparticles are arranged at intervals of nanometers or subnanometers, the intrinsic properties of the nanoparticles are mutually influenced and exhibit a unique change that is different from that of the enhancement or appearance of one nanoparticle . In the case of platinum nanoparticles, optical properties based on plasmon phenomena are expected to show such changes. However, it is technically not easy to arrange several metallic nanoparticles very close together at intervals, because nearby metallic nanoparticles stick together to form an aggregation. Therefore, the technique of arranging one or more platinum nanoparticles very closely spaced apart from each other is a very difficult but important technique.

In addition, it is important to make the silica nanoparticles containing metallic nanoparticles into a spherical shape. Generally, particles synthesized by incorporating multiple metals into silica are difficult to form a spherical shape because they are likely to form a snowman shape rather than a spherical shape, Therefore, it is meaningful in terms of a certain type of controllable expression, which is one of the important part of nanotechnology. Also, when using the gold nano dot-containing silica nanoparticles manufactured for the purpose of sensing, it is important to make the nanoparticles have a uniform size, When the shape of the nanoparticles is spherical, it is advantageous in that the size can be easily controlled.

The inventors of the present invention have found that a plurality of platinum nanodots can form highly spherical nanoparticles that form a core with intervals of sub-nanometers and are surrounded by silica, Thereby providing outer nanoparticles.

According to the method of the present invention, nanoparticles containing a plurality of platinum nanodots in a spaced-apart relationship with each other within a silica shell can be synthesized by a simple method.

Further, according to the method of the present invention, it is possible to synthesize a two-component nanoparticle containing a plurality of gold and platinum nanodots in an outer portion of the silica at an interval from each other.

Further, according to the method of the present invention, it is possible to synthesize a nano-chain containing several platinum nanodots at an interval from each other in an outer portion of the silica.

These nanomaterials synthesized by the present invention can be applied as an efficient catalyst or energy transfer material.

1 (a) is a transmission electron microscope (TEM) photograph of platinum nanoparticles synthesized in Brij 35 ( aq . ) Solution. (b) is the size (particle diameter) distribution of synthesized platinum nanoparticles.
2 (a) is a scanning electron microscope (SEM) photograph of m-Pt @ SiO ₂ nanoparticles. (b) is the size distribution of m-Pt @ SiO ₂ nanoparticles. (c) is a transmission electron micrograph of m-Pt @ SiO ₂ nanoparticles.
FIG. 3 is a transmission electron micrograph of m-Pt @ SiO ₂ nanoparticles grown by adding (a) ascorbic acid or (b) glucose without changing the original synthesis conditions. In order to synthesize m-Pt @ SiO ₂ NPs by the addition of a reducing agent, the same procedure as in the synthesis of m-Pt @ SiO ₂ nanoparticles was carried out. K ₂ PtCl ₄ (aqueous solution) was added to the reverse microemulsion and then ascorbic acid mL, 0.1 M) or glucose (0.1 mL, 0.1 M) was added.
4 is a TEM photograph of the grown m-Pt @ SiO ₂ silica nanochain. The arrows in (c) indicate platinum nanodots located in the silica nanocycles.
5 is m-Au / Pt @ SiO ₂ Fig. 3 is a schematic diagram showing a method for synthesizing nanoparticles. Fig.
6 (a) and 6 (b) show the growth of m-Au / Pt @ SiO ₂ TEM photograph of nanoparticles. (c) is the result of EDX (Elemental analysis).

Hereinafter, the configuration of the present invention will be described in more detail with reference to specific embodiments. However, it is apparent to those skilled in the art that the scope of the present invention is not limited to the description of the embodiments.

material

Polyoxyethylene glycol dodecyl ether, (C ₂ H ₄ O) ₂₃ C ₁₂ H ₂₅ OH, Brij 35, Acros Organics}, TEOS (traethylorthosilicate, 99%, Sigma-Aldrich), chloroplatinic acid (II), potassium tetrachloroplatinate (II), K ₂ PtCl ₄ , Sigma-Aldrich), chloride (III) chloride trihydrate, HAuCl ₄ .H ₂ O, 99.9%, Sigma-Aldrich) ammonium hydroxide _{(ammonium hydroxide, NH 4 OH,} 28-30 wt% ammonia, Sigma-Aldrich), cyclohexane _{(cyclohexane, C 6 H 12,} 99%, Sigma-Aldrich), n- hexanol (n-hexanol, C _{6 H 5 OH, 98%,} Sigma-Aldrich), L- ascorbic acid _{(L-ascorbic acid, C 6} H 8 O 6, 99 +%, Sigma-Aldrich), D - (+) - glucose (C ₆ H ₁₂ O ₆ , = 99.5%, Sigma-Aldrich), HCl, HNO ₃ , acetone and ethyl alcohol were used as received. All stock solutions were prepared before the reaction. All glass containers prior to use aqua regia:;: washing with (HCl HNO ₃ in a volume ratio of 3 with 1 mixture) and rinsed with ultra-pure water.

Two types of platinum Nano dot  The combination (m- Pt ) Core-silica outer nanoparticles m-Pt @ SiO ₂ NPs And m-Pt @ SiO 2 NChs  synthesis

For the synthesis of m-Pt @ SiO ₂ NPs, the synthesis method used for the synthesis of multi-nano dots core-silica nanoparticles (multi-Au @ SiO ₂ NPs) was modified (9). The reverse microemulsion was prepared by mixing Brij 35 (2.0 g), cyclohexane (7.7 ml) and cosurfactant (n-hexanol, 1.6 ml) and sonicating to dissolve completely. 0.1 ml of 0.1 MK ₂ PtCl ₄ (aqueous solution) was added to the reverse microemulsion and the mixture was sonicated at room temperature for 30 minutes. Then, while stirring for 30 minutes, 50 μl of TEOS and 500 μl of ammonium hydroxide (aqueous solution) (14.8 M) were added sequentially to the reverse microemulsion, and the reaction mixture was further stirred at room temperature for 12 hours. After completion of the reaction, the microemulsion system was destabilized by adding acetone (20 ml), followed by centrifugation at 2000 rpm for 5 minutes to obtain synthesized nanoparticles (m-Pt @ SiO ₂ NPs) Washed and centrifuged (13350 rpm, 5 minutes).

For the experiment of synthesizing m-Pt @ SiO ₂ NPs by adding a reducing agent, the same procedure as above was carried out for comparison except for the above experiment. After K ₂ PtCl ₄ (aqueous solution) was added to the reverse microemulsion, (0.1 mL, 0.1 M) or hyperglucose (0.1 mL, 0.1 M) was added to the reaction mixture. (The procedure below is the same as above.)

Brij 35 (2.0 g), cyclohexane (7.7 ml), cosurfactant (n-hexanol, 1.6 ml) and 0.5 ml of HCl (aqueous solution) (1 ml) for the synthesis of m-Pt @ SiO ₂ NChs M) were ultrasonicated and mixed. 0.1 ml of K ₂ PtCl ₄ (aqueous solution) (0.1 M) was added to the reaction mixture and ultrasonicated at room temperature for 30 minutes. Then, while stirring for 30 minutes, 50 μl of TEOS and 500 μl of ammonium hydroxide (aqueous solution) (14.8 M) were added sequentially to the reverse microemulsion, and the reaction mixture was further stirred at room temperature for 6 hours. After completion of the reaction, the microemulsion system was destabilized by adding acetone (20 ml), washed repeatedly with ethanol three times, and centrifuged (13350 rpm, 5 minutes) to obtain synthesized nanoparticles ((m-Pt @ SiO ₂ NChs) Lt; / RTI >

Two components  Gold / platinum Nano dot  The combination (m- Au / Pt ) Core-silica outer nano system (m-Au / Pt < RTI ID = 0.0 > ₂ NPs ) synthesis

The reverse microemulsion was prepared by mixing Brij 35 (2.0 g), cyclohexane (7.7 ml) and cosurfactant (n-hexanol, 1.6 ml) and sonicating to dissolve completely. 0.1 MK ₂ PtCl ₄ (aqueous solution), ascorbic acid (0.1 mL, 0.1 M) and 0.03 mL HAuCl ₄ (aqueous solution) (0.1 M) were sequentially added to the reverse microemulsion and the mixture was sonicated for 30 minutes at room temperature Respectively. Then, while stirring for 30 minutes, 50 μl of TEOS and 500 μl of ammonium hydroxide (aqueous solution) (14.8 M) were added sequentially to the reverse microemulsion, and the reaction mixture was further stirred at room temperature for 12 hours. After completion of the reaction, the microemulsion system was destabilized by adding acetone (20 mL) and centrifuged at 2000 rpm for 5 minutes. The prepared m-Au / Pt @ SiO ₂ NPs were washed three times with ethanol and centrifuged (13350 rpm, 5 minutes).

Characterization

The obtained nanoparticles were photographed using a Hitachi S-4800 scanning electron microscope (SEM) and a LEO-912AB OMEGA (Carl ZeisGerman) transmission cell microscope (TEM). EDX (energy dispersive X-ray) analysis was performed using a JEOL JEM-2100F (Japan) microscope.

Samples for TEM analysis were obtained by centrifuging the nanoparticle mixture at 13500 rpm for 5 minutes twice and concentrating. The particles were then resuspended in 100 μl of ultrapure water and fixed with 10 μl of solution on a Formvar coated copper electrode. UV-visible spectra were recorded with a UV Spectrophotometer (UV-1800 Shimadzu).

result

Water soluble K ₂ PtCl ₄ and HAuCl ₄ solutions were used to grow nanoparticles of silica matrix shells in a platinum nano-dot combination (m Pt Pt) core and a two-component gold / platinum nano-dot combination (m-Au / Pt) core . In general, HAuCl ₄ (aqueous solution) is easily reduced in Brij 35 aqueous solution without any reducing agent, and a pair of anisotropic gold nanoparticles can be synthesized by using Brij surfactant as a reducing agent and shape indicator (9, 10, 23 , 24,25). In addition, gold nanodots could successfully synthesize and aggregate with Brij35 aqueous solution in silica (9). On the other hand, K ₂ PtCl ₄ denotes a lower reducing power (reference:. Bard, AJ et al Standard Potentials in Aqueous Solution, Marcel Dekker, New York, 1985.), therefore in order to reduce the K ₂ PtCl ₄ (aqueous solution) is generally A stronger reducing agent or other kind of reaction conditions (e.g., a high reaction temperature) are required. In the present invention, it has been found that K ₂ PtCl ₄ (aqueous solution) can be reduced by Brij 35, and thus, platinum nanoparticles having a particle diameter of 1 to 2 nm can be produced. Figure 1 shows that Brij35 alone can be used as a reducing agent effective for the synthesis of platinum nanoparticles without any other adjuvant.

In order to synthesize multi-platinum nano-dot core-silica external nanoparticles (m-Pt @ SiO ₂ NPs), an inverted microemulsion system was employed. The microemulsions were prepared by thoroughly mixing and dissolving Brij 35, n-hexanol and cyclohexane by ultrasonication. K ₂ PtCl ₄ (aqueous solution), TEOS and NH ₄ OH were added sequentially to the reverse microemulsion and the reaction mixture was stirred at room temperature for 12 hours. After completion of the reaction, acetone was added to destabilize the microemulsion system, and the synthesized m-Pt @ SiO ₂ NPs were repeatedly washed with ethanol and centrifuged. FIG. 2A is a SEM image of m-Pt @ SiO ₂ NPs showing clearly that the reverse microemulsion system is very well suited to the formation of spherical silica forms with a narrow size distribution. The average particle size of the individual silica nanoparticles was 43.3 5.48 nm (the result of evaluating 100 or more silica nanoparticles (FIG. 2b)), which is a multiple gold nanodot core- silica outer nanoparticle -Au @ SiO ₂ NPs). TEM photographs of m-Pt @ SiO ₂ NPs (FIGS. 2c and 2d) show that there are several platinum nanodots within each silica particle. Platinum nanodots are not strictly limited in location. Most platinum nanodots in m-Pt @ SiO ₂ NPs are concentrated at the center of the silica matrix with narrow nano spacing, but several platinum nanodots are also observed near the surface of the silica. The average particle diameter of platinum nanodots was 5.2 ± 3.3 nm (the result of evaluating 100 or more silica nanoparticles (FIG. 2c)). This value is very similar to the average particle size of platinum nanoparticles grown in Brij 35 (aqueous solution) without silica formation (Fig. 1).

In order to investigate the growth mechanism of platinum nano-dot combinations in m-Pt @ SiO ₂ NPs, we have adjusted the reaction temperature (up to 50 ° C), NH ₄ OH, concentration and TEOS. However, the basic shape of m-Pt @ SiO ₂ NPs and the size and number of platinum nanodots in each silica nanoparticle did not change significantly. The present inventors have also observed the use of ascorbic acid and glucose as auxiliary reducing agents, but little change was observed in the structure of m-Pt @ SiO ₂ NPs (FIG. 3). The average particle size of platinum nano dot was 3.6 2.3 nm in FIG. 3A and 3.1 2.1 2.1 nm in FIG. 3B, which was similar to the value measured in FIG. It was observed that the shape of m-Pt @ SiO ₂ NPs hardly changed. The photograph shows clearly spherical nanoparticles in both systems, and that oval m-Pt @ SiO ₂ NPs are also present. To emphasize, although these photographs are observed, platinum nanodots are mostly located in the center of the silica matrix. Despite the addition of a reductant, there was no significant change in the system, and nanoparticles with well controlled morphology were still obtained.

Inverse microemulsion (water / water) -based strategies for synthesizing multi-platinum nanodet combinations (m-Pt) core-silica outer nanoparticles can be extended to the production of one-dimensional nanostructures applicable to energy materials. In order to combine platinum nanoparticles within a one-dimensional silica matrix, the present inventors have attempted to grow platinum nanoparticles in situ while the silica material is grown one-dimensionally in a modified microemulsion system. By simply changing the pH of the reaction medium, we were able to successfully synthesize silica nanocycles (m-Pt @ SiO ₂ NChs) with platinum nanoparticles interposed, with an average width of 20.3 ± 5.5 nm (more than 100 nanoseconds (Fig. 4) (26). More importantly, platinum nanodots are located within the silica nanocycles (FIG. 4c). The average particle size of platinum nano dot is 5.3 ± 2.2 nm, which is very large when compared with the particle size of platinum nano dot in m-Pt @ SiO ₂ . It is believed that the pre-fabricated platinum nano dot is partly aggregated during the growth of the silica nanocycle structure. This m-Pt @ SiO ₂ NChs is applicable to hydrogen storage composites or energy materials (27).

The emphasis is not only on dimensional aspects, but also on the impact of the surrounding environment. The nature of the metal nanoparticles can be changed by the surrounding environment, such as the presence of other particles, and as a result some new important properties may appear. In order to study the properties of platinum nanodots surrounded by gold nanodots at intervals of nanometers, the present inventors have attempted to fabricate a system in which a binary gold / platinum nanodot core is contained within the silica outer shell. K ₂ PtCl ₄ , ascorbic acid, and HAuCl ₄ were sequentially added to the reverse microemulsion to prepare a two-component Au / Pt nanodot The combination (m-Au / Pt) core-silica outer nano system (m-Au / Pt @ SiO ₂ NPs) (Fig. 5).

SEM and TEM images (Figs. 6A and 6B) of m-Au / Pt @ SiO ₂ NPs show that most of the metal nanodots are clustered and are closely clustered within the silica nanoparticles. No metal nanoparticles were found outside the silica matrix, indicating that the reverse microemulsion using Brij35 is effective for a two-component Au / Pt nanodat combination in the silica shell. It is not easy to distinguish between gold and platinum nanodots in these photographs, but in conclusion, X-ray energy dispersive spectroscopy (EDS) revealed the presence of gold and platinum in the silica matrix ). Both gold and platinum were observed from the spot A located at the center of the silica nanoparticles, which indicates that most of the gold and platinum are combined to form a central portion of the silica nanosphere. In addition, some smaller nanodots were found on the side of silica nanoparticles (Spot B, Spot C in Figure 6b), and these particles were platinum. Based on these results, the present inventors have found that the location of the multiple gold nano-dot combinations is confined to the center of the silica, while the platinum nano dot is relatively broadly distributed. The different distribution of nanodots appears to be derived from the growth kinetics of gold nanoparticles and platinum nanoparticles, respectively, because the reduction rates of Au ^{3 +} and Pt ^{2 +} in reverse micelles are different and are competitive with each other. In the synthesis, K ₂ PtCl ₄ was first added to the reaction mixture, and then HAuCl ₄ was added, and this sequential addition balances the procedure of the K ₂ PtCl ₄ and HAuCl ₄ reduction processes. In the reaction, HAuCl ₄ was added prior to K ₂ PtCl ₄ to synthesize each single-component core-silica outer nanoparticle (m-Au @ SiO ₂ NPs and m-Pt @ SiO ₂ NPs) @ SiO ₂ NPs were not synthesized. This shows that careful control of the reaction rate is essential for the successful synthesis of m-Au / Pt @ SiO ₂ NPs.

In FIG. 6, almost all of the silica nanoparticles have a spherical shape, and the average particle size of the individual silica nanoparticles is 52.8. 6.7 nm (more than one hundred nanoparticles were measured). The average particle size of platinum nanodots was 2.5 ± 1.8 nm and the average particle size of gold nanodots was 5.6 ± 3.5 nm (more than 100 silica nanoparticles were measured). In particular, the average particle size of individual silica nanoparticles was 52.8 ± 6.7 nm (more than 100 silica nanoparticles were measured), and gold nanodots were much larger. As a result, the different distributions of nanodots can be explained by the different rates of the platinum and gold ions during the synthesis process.

The present inventors successfully synthesized spherical nanoparticles and one-dimensional nano chains surrounded by platinum multi-nano dot silica. Platinum nano dot multiple combination (m-Pt) core-silica outer nanosystems _{(m-Pt @ SiO 2 NPs} ( spherical nanoparticles) and m-Pt @ SiO ₂ NChs (nanochain)) were synthesized by reverse microemulsion (water - in - oil) - based method. In essence, K ₂ PtCl ₄ was effectively reduced by Brij 35 in the silica shell to form platinum nanodots. A nano-dot combination (m-Au / Pt) core-silica outer nano system (m-Au / Pt @ SiO ₂ NPs) with a platinum / gold double composition was also synthesized. Reduction of kinetic controlled HAuCl ₄ and K ₂ PtCl ₄ by Brij 35 surfactant in reverse micelles and condensation of TEOS formed a hybrid multimetallic core-silica shell system. This can be applied as an efficient catalyst or energy transfer material.

Claims (13)

a) preparing a microemulsion by mixing a nonpolar surfactant selected from polyoxyethylene glycol dodecyl ether, glycerin fatty acid ester, sucrose fatty acid ester and sorbitan fatty acid ester as a nonpolar organic solvent and a main reducing agent; ;
b) adding a cationic platinum precursor-containing aqueous solution to the microemulsion and subjecting the microemulsion to ultrasonic treatment to produce a reversed microemulsion containing the platinum solution; And
c) A silica precursor and an aqueous ammonia solution are sequentially added while stirring the reversed microemulsion containing the platinum solution and the mixture is stirred to reduce the Pt ²⁺ precursor with the nonionic surfactant, which is the main reducing agent, and the auxiliary reducing agent, And synthesizing nanoparticles composed of an outer shell of silica, and a method of synthesizing spherical nanoparticles of outer shell of silica.
The method according to claim 1,
Wherein the silica precursor is at least one selected from the group consisting of tetraethyl orthosilicate, tetramethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl ortho silicate, tetrachlorosilane and sodium silicate. Synthesis of spherical nanoparticles.
The method according to claim 1,
Wherein the auxiliary reducing agent is at least one selected from ascorbic acid and glucose. 2. The method of claim 1, wherein the auxiliary reducing agent is at least one selected from the group consisting of ascorbic acid and glucose.
The method according to claim 1,
Wherein b) a cationic platinum precursor of step tetrachloride acid (Ⅱ) potassium {potassium tetrachloroplatinate (Ⅱ), K 2 PtCl 4}, platinum chloride (Ⅱ) {platinum (Ⅱ) chloride}, dichloride platinum (PtCl _2), The platinum bromide (PtBr ₂ ), Am Eau Chemistry platinum (PtI _2), Platinum (Ⅱ) acetylacetonate {Platinum (Ⅱ) acetylacetonate}, dichloro (ethylenediamine) platinum (Ⅱ) (acac) ₂ {Dichloro (ethylenediamine) platinum (Ⅱ) (acac ) ₂ } and a platinum divalent transition metal compound selected from potassium bis (oxalato) platinum (II) dihydrate K ₂ Pt (C ₂ O ₄ ) ₂ .2H ₂ O} Wherein the spherical nanoparticles are composed of polyplatinum nanodots core and silica.
A spherical nanoparticle synthesized by the method of any one of claims 1 to 4 and consisting of a multi-platinum nanodot core and a silica outer shell, wherein a plurality of platinum nanodots are encapsulated in a silica outer shell.
a) mixing a nonionic surfactant, a nonpolar organic solvent and an acid to prepare a microemulsion;
b) adding a cationic platinum precursor-containing aqueous solution to the microemulsion and subjecting the microemulsion to ultrasonic treatment to produce a reversed microemulsion containing the platinum solution; And
c) synthesizing nanoparticles composed of polyplatinum nanodots core and silica by sequentially adding a silica precursor and a basic catalyst while stirring the reverse microemulsion containing the platinum solution and stirring the nanoparticles, A method for synthesizing a one - dimensional nanochain made of silica.
A one-dimensional nano-chain produced by the method of claim 6 and consisting of a multi-platinum nano-dot core and a silica outer shell.
a) mixing a nonionic surfactant and a nonpolar organic solvent to prepare a microemulsion;
b) sequentially adding an aqueous solution containing a cationic platinum precursor, an acid solution and an aqueous solution containing a cationic gold precursor to a microemulsion and subjecting the microemulsion to ultrasonic treatment to prepare an inverted microemulsion containing platinum and gold solutions; And
c) synthesizing a nano-dot combination core of a platinum / gold double composition core and silica nanoparticles by sequentially adding and stirring a silica precursor and a basic catalyst while stirring the reverse microemulsion; Synthesis of spherical nanoparticles composed of nano - dot combination cores and silica shells.
The method of claim 8,
Wherein b) a cationic gold precursor of step is chloroauric acid, potassium (KAuCl _4), chloroauric acid sodium (NaAuCl _4), chloroauric acid (HAuCl _4), brominated Keumsan sodium (NaAuBr _4), yeomhwageum (AuCl), yeomhwageum (Ⅲ) (AuCl ₃ ) and gold bromide (AuBr ₃ ). The method of synthesizing spherical nanoparticles comprising a nanodet combination core of platinum / gold double composition and silica.
A spherical nanoparticle synthesized by the method of any one of claims 8 to 9 and comprising a platinum / gold double-composition nanodet combination core and a silica outer shell, wherein a plurality of gold nanodots and platinum nanodots are encapsulated within the silica outer shell. delete delete delete

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