KR20210103421A - Hydrogen production reaction catalyst comprising dendrimer-encapsulated nanoparticles - Google Patents

Abstract

An embodiment of the present invention provides a hydrogen production reaction catalyst and a catalyst complex including the same, wherein the hydrogen production reaction catalyst includes a dendrimer and nanoparticles encapsulated inside the dendrimer, and the nanoparticles are made of an alloy of platinum and palladium and reduce the activation energy of a hydrogen production reaction.

Description

Dendrimer-encapsulated nanoparticles containing hydrogen generation reaction catalyst {HYDROGEN PRODUCTION REACTION CATALYST COMPRISING DENDRIMER-ENCAPSULATED NANOPARTICLES}

The present specification relates to a hydrogen production catalyst including dendrimer-encapsulated nanoparticles and a catalyst complex including the same.

As a versatile method for synthesizing nanoparticles of defined size, composition and structure, the use of dendrimer templates is preferred in a variety of nanoparticle systems. The method of synthesizing nanoparticles using a dendrimer template generally has two steps, namely, a step in which metal ions are complexed in the dendrimer to form a complex, and a step in which the complexed ions in the complex are reduced to form nanoparticles (NP). is composed These types of nanoparticles, commonly referred to as dendrimer-encapsulated nanoparticles (DENs), offer significant advantages over other types of nanoparticles, primarily due to the desirable function of dendrimers.

The size and composition of DENs can be precisely controlled by selecting the proportion and type of metal ions complexed to the dendrimer. In addition, the structure of DENs can be controlled by controlling the complexation and reduction processes of metal ions inside the dendrimer. In addition, dendrimers stabilize the encapsulated nanoparticles with minimal passivation of the catalytic nanoparticle surface, as well as control over the solubility and catalyst selectivity of DENs.

DENs can realize unique advantages in a very small range, where their size is less than 2 nm. Nanoparticles rapidly change their physicochemical properties even with changes in sub-nanometer size. Therefore, DENs are attracting attention in various fields including drug delivery, sensors and catalysis.

However, there is a fixed number of complexing sites (sites) in the dendrimer, which limits the number of metal ions that can be complexed inside the dendrimer during the synthesis of DENs. Therefore, the number of metal atoms in DENs is generally limited to less than 250, which narrows the scope of application of DENs. Since the number of complex formation sites depends on the number of generations of dendrimers, the synthesis of large DENs containing more than 250 atoms requires high-generation dendrimers such as 9th-generation polyamidoamine (PAMAM) dendrimers. However, in the case of high-generation dendrimers, their use is limited due to a very large internal volume, high density of end groups, and high cost of high-generation dendrimers.

In this regard, a method for improving catalytic activity by increasing the number of metal atoms of DENs has been studied, but a method for improving catalytic activity while maintaining a similar size by including the same amount of metal atoms or by supporting DENs on a carrier Developing a method to improve activity can lead to better catalysts.

The description of the present specification is intended to solve the problems of the prior art described above, and an object of the present specification is to provide a catalyst for hydrogen production having improved catalytic activity and a catalyst composite including the same.

According to one aspect, it includes a dendrimer and nanoparticles encapsulated inside the dendrimer, wherein the nanoparticles are made of an alloy of platinum and palladium, and reduce the activation energy of the hydrogen generation reaction, there is provided a hydrogen generation reaction catalyst.

In one embodiment, the dendrimer may be a hydroxyl-terminated polyamidoamine dendrimer.

In one embodiment, the total molar equivalent of the nanoparticle constituents may be 16 to 1024 equivalents based on 1 equivalent of the dendrimer.

In one embodiment, the average particle size of the nanoparticles may be 1.0 ~ 3.5 nm.

In one embodiment, the average particle size of the nanoparticles may be a monodisperse of 1.65 ~ 1.75 nm.

In one embodiment, the molar ratio of the platinum and the palladium may be 1-5: 5-1, respectively.

In one embodiment, the molar ratio of the platinum and the palladium may be 1 to 2: 2 to 1, respectively.

In one embodiment, the turnover frequency (TOF) of the hydrogen generation reaction using the catalyst may be 50 mol _H2 mol _atom ^-1 min ^{-1 or} more.

In one embodiment, the catalyst may reduce the activation energy of the hydrogen generation reaction to 57.5 kJ/mol or less.

In one embodiment, the hydrogen generation reaction may be a hydrolysis dehydrogenation reaction of ammonia borane.

According to another aspect, it comprises a carbon-based carrier and a catalyst supported on the carbon-based carrier, wherein the catalyst comprises a dendrimer and nanoparticles encapsulated inside the dendrimer, and the nanoparticles are platinum, palladium, or platinum and It is made of an alloy of palladium, and provides a hydrogen production reaction catalyst composite which reduces the activation energy of the hydrogen production reaction.

In one embodiment, the dendrimer may be an amine-terminated polyamidoamine dendrimer.

In one embodiment, the total molar equivalent of the nanoparticle constituents may be 16 to 1024 equivalents based on 1 equivalent of the dendrimer.

In one embodiment, the average particle size of the nanoparticles may be 1.0 ~ 3.5 nm.

In one embodiment, the carbon-based carrier may be chemically processed graphene (CCGs).

In one embodiment, the carbon-based carrier may be graphene oxide or reduced graphene oxide.

In one embodiment, the molar ratio of platinum and palladium included in the alloy may be 1 to 2: 2 to 1, respectively.

In one embodiment, the turnover frequency (TOF) of the hydrogen generation reaction using the catalyst complex may be 90 mol _H2 mol _atom ^-1 min ^{-1 or} more.

In one embodiment, the catalyst complex may reduce the activation energy of the hydrogen generation reaction to 57.5 kJ/mol or less.

In one embodiment, the hydrogen generation reaction may be a hydrolysis dehydrogenation reaction of ammonia borane.

The hydrogen generation reaction catalyst according to an aspect of the present specification can control or improve the catalytic activity by changing only the nanoparticle composition.

The hydrogen generation reaction catalyst composite according to an aspect of the present specification may improve catalytic activity by supporting the catalyst on a carrier.

The hydrogen generation reaction catalyst and the catalyst composite including the same according to an aspect of the present specification have excellent dehydrogenation reaction catalytic activity, and thus can be applied to the production of hydrogen fuel used in hydrogen vehicles and the like.

The effect of one aspect of the present specification is not limited to the above-described effect, but it should be understood to include all effects that can be inferred from the configuration described in the detailed description or claims of the present specification.

1 is a TEM image and a particle size distribution histogram of a dendrimer-encapsulated nanoparticle according to an embodiment of the present specification.
Figure 2 is a dendrimer-encapsulated nanoparticles according to an embodiment of the present specification HAADF-STEM image and elemental analysis results.
Figure 3 shows the XPS spectrum of the dendrimer-encapsulated nanoparticles according to an embodiment of the present specification.
Figure 4 shows the XPS spectrum in the Pt (4f) region and the Pd (3d) region of the dendrimer-encapsulated nanoparticles according to an embodiment of the present specification.
5 is a dendrimer-encapsulated platinum-palladium nanoparticle according to an embodiment of the present specification, measured using ICP-AES, showing the content ratio of platinum and palladium.
6 is a dendrimer-encapsulated nanoparticle according to an embodiment of the present specification, and is an apparatus for evaluating catalytic activity for hydrogen production.
7 shows time-dependent hydrogen generation of dendrimer-encapsulated nanoparticles according to an embodiment of the present specification.
8 is a dendrimer according to an embodiment of the present specification-shows a change in the TOF value according to the composition ratio of the encapsulated nanoparticles.
9 is a dendrimer-encapsulated nanoparticle according to an embodiment of the present specification showing a change in activation energy and an Arrhenius diagram for a hydrogen production reaction.
10 is an HRTEM image of a dendrimer-encapsulated nanoparticle according to an embodiment of the present specification.
11 is a UV-Vis spectrum of the dendrimer-encapsulated nanoparticles-graphene oxide complex synthesis process according to an embodiment of the present specification.
12 is a TEM image of a dendrimer-encapsulated nanoparticles-graphene oxide complex and a histogram of particle size distribution of dendrimer-encapsulated nanoparticles on graphene oxide according to an embodiment of the present specification.
13 shows a time-dependent hydrogen generation before and after graphene oxide loading of dendrimer-encapsulated nanoparticles according to an embodiment of the present specification.
14 is a dendrimer-encapsulated nanoparticle according to an embodiment of the present specification showing a change in TOF value before and after graphene oxide loading.
15 is a TEM image and a particle size distribution histogram before and after carbon black loading of dendrimer-encapsulated nanoparticles according to an embodiment of the present specification.
16 is a dendrimer-encapsulated nanoparticle according to an embodiment of the present specification, showing time-dependent hydrogen production and changes in TOF values according to types of catalyst carriers.
17 is a dendrimer-encapsulated nanoparticle-graphene oxide composite according to an embodiment of the present specification, showing thermal stability test results.
18 is a TEM image and particle size distribution histogram after heat treatment of a dendrimer-encapsulated nanoparticle-graphene oxide composite according to an embodiment of the present specification.

Hereinafter, one aspect of the present specification will be described with reference to the accompanying drawings. However, the description of the present specification may be implemented in several different forms, and thus is not limited to the embodiments described herein. And in order to clearly explain one aspect of the present specification in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a part is "connected" with another part, this includes not only the case where it is "directly connected" but also the case where it is "indirectly connected" with another member interposed therebetween. . In addition, when a part "includes" a certain component, this means that other components may be further provided without excluding other components unless otherwise stated.

When a range of numerical values is recited herein, the values have the precision of the significant figures provided in accordance with the standard rules in chemistry for significant figures, unless the specific range is otherwise stated. For example, 10 includes the range of 5.0 to 14.9 and the number 10.0 includes the range of 9.50 to 10.49.

Hereinafter, an embodiment of the present specification will be described in detail with reference to the accompanying drawings.

hydrogen production reaction catalyst

The hydrogen generation reaction catalyst according to an aspect of the present specification includes a dendrimer and nanoparticles encapsulated inside the dendrimer, and the nanoparticles are made of an alloy of platinum and palladium, and may be to reduce the activation energy of the hydrogen generation reaction have.

The encapsulation means that the nanoparticles are surrounded by branches of the dendrimer having a regular branching structure.

The dendrimer may be a hydroxyl-terminated polyamidoamine dendrimer. For example, it may be a 2nd generation, 3rd generation, 4th generation, 5th generation, 6th generation, 7th generation, or 8th generation polyamidoamine dendrimer, but is not limited thereto. Generation n dendrimers may have 2 ⁿ⁺² end groups. Older dendrimers contain a higher number of end groups, but have very large internal volumes and high end group density and can be uneconomical.

The total molar equivalent of the nanoparticle component may be 16 to 1024 equivalents based on 1 equivalent of the dendrimer. For example, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330, 360, 390, 420, 450, 480, 510, 550, 600, 650, 700, per mole of dendrimer. 750, 800, 850, 900, 950 or 1000 moles of the component may be encapsulated, but is not limited thereto. The nanoparticle component may mean a concept including all of a platinum atom, a platinum ion, a palladium atom, and a palladium ion.

The nanoparticles may have an average particle size of 1.0 to 3.5 nm, or a monodisperse having an average particle size of 1.65 to 1.75 nm. As the number of components of the dendrimer-encapsulated nanoparticles increases, the average particle size may increase, and if the particle size of the dendrimer-encapsulated nanoparticles has a monodisperse form with precisely controlled particle size, the nanoparticles may be more stabilized.

The molar ratio of the platinum and the palladium may be 1-5: 5-1, respectively. For example, the molar ratio of the platinum and the palladium may be 1 to 2: 2 to 1, respectively. Since the platinum and the palladium form a bimetallic structure, the activity of the catalyst can be precisely controlled by controlling the molar ratio of the platinum and the palladium constituting the nanoparticles regardless of the size effect. For example, the molar ratio of platinum and palladium may be 30: 150, 60: 120, 90: 90, 120: 60, or 150: 30, but is not limited thereto.

A turnover frequency (TOF) of the hydrogen generation reaction using the catalyst may be 50 mol _H2 mol _atom ^-1 min ^{-1 or} more. For example, 50 mol _H2 mol _atom ^-1 min ^-1 , 60 mol _H2 mol _atom ^-1 min ^-1 , 70 mol _H2 mol _atom ^-1 min ^-1 , 80 mol _H2 mol _atom ^-1 min ^-1 , 90 mol _{It may be H2} mol _atom ^-1 min ^-1 100 mol _H2 mol _atom ^-1 min ^-1 , 110 mol _H2 mol _atom ^-1 min ^{-1 ,} or 120 mol _H2 mol _atom ^-1 min ^-1 , but is not limited thereto.

The catalyst may reduce the activation energy of the hydrogen generation reaction to 57.5 kJ/mol or less. For example, it may be 55 kJ/mol, 52.5 kJ/mol, 50 kJ/mol, or 47.5 kJ/mol, but is not limited thereto.

The hydrogen generation reaction refers to a reaction for generating _{hydrogen (H 2} ) through dehydrogenation of a chemical hydrogen storage material. Chemical hydrogen storage materials include solid or liquid organic compounds containing hydrogen, organic-inorganic complexes, etc. For example, hydrogenated materials such as methyl-cyclohexane (MCH), N-methylcarbazole, dibenzyltoluene, and ammonia borane It may be a compound, but is not limited thereto.

The hydrogen production reaction may be a hydrolysis dehydrogenation reaction of ammonia borane (ammonia borane, AB, NH ₃ BH _{3 ).} The hydrolysis and dehydrogenation reaction of ammonia borane using the catalyst may be to produce 3 moles of hydrogen per 1 mole of ammonia borane. The ammonia borane is attracting attention as a hydrogen storage material due to its high hydrogen capacity of 19.6% by weight, non-toxicity and excellent stability. It presents conditions with high hydrogen selectivity in practical applications, including

Hydrogen production reaction catalyst complex

The hydrogen generation reaction catalyst composite according to another aspect of the present specification includes a carbon-based support and a catalyst supported on the carbon-based support, wherein the catalyst includes a dendrimer and nanoparticles encapsulated in the dendrimer, and the nanoparticles is made of platinum, palladium, or an alloy of platinum and palladium, and may reduce the activation energy of the hydrogen production reaction.

The encapsulation means that the nanoparticles are surrounded by branches of the dendrimer having a regular branching structure.

The dendrimer may be an amine-terminated polyamidoamine dendrimer. For example, it may be a 2nd generation, 3rd generation, 4th generation, 5th generation, 6th generation, 7th generation, or 8th generation polyamidoamine dendrimer, but is not limited thereto. Generation n dendrimers may have 2 ⁿ⁺² end groups. Older dendrimers contain a higher number of end groups, but have very large internal volumes and high end group density and can be uneconomical.

The total molar equivalent of the nanoparticle component may be 16 to 1024 equivalents based on 1 equivalent of the dendrimer. For example, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330, 360, 390, 420, 450, 480, 510, 550, 600, 650, 700, per mole of dendrimer. 750, 800, 850, 900, 950 or 1000 moles of the component may be encapsulated, but is not limited thereto. The nanoparticle component may mean a concept including all of a platinum atom, a platinum ion, a palladium atom, and a palladium ion.

The nanoparticles may have an average particle size of 1.0 to 3.5 nm. As the number of components of the dendrimer-encapsulated nanoparticles increases, the average particle size may increase, and if the particle size of the dendrimer-encapsulated nanoparticles has a monodisperse form with precisely controlled particle size, the nanoparticles may be more stabilized.

The difference in particle size of the nanoparticles before and after the catalyst is supported on the carbon-based carrier is 1.0 nm or less, 0.9 nm or less, 0.8 nm or less, 0.7 nm or less, 0.6 nm or less, 0.5 nm or less, 0.4 nm or less, 0.3 nm or less Or it may be 0.2 nm or less, but is not limited thereto.

The carbon-based carrier may be chemically converted graphene (CCGs). For example, the carbon-based carrier may be graphene oxide or reduced graphene oxide, but is not limited thereto.

The chemically processed graphene (CCGs) is graphene prepared by a chemical synthesis method, and the graphene produced by the chemical synthesis method can be synthesized in a large amount and has the advantage that it can be synthesized at a relatively low cost.

The catalyst complex is formed by covalently bonding the amine group at the end of the dendrimer and the epoxy group of the carbon-based carrier, for example, graphene oxide, so that the dendrimer-encapsulated nanoparticles are uniformly dispersed and fixed on the surface of the carbon-based carrier. can

The molar ratio of platinum and palladium included in the alloy may be 1 to 2: 2 to 1, respectively. For example, a molar ratio of platinum and palladium included in the alloy may be 60: 120, 90: 90, or 120: 60, but is not limited thereto.

A turnover frequency (TOF) of the hydrogen generation reaction using the catalyst complex may be 90 mol _H2 mol _atom ^-1 min ^{-1 or} more. For example, 90 mol _H2 mol _atom ^-1 min ^-1 , 100 mol _H2 mol _atom ^-1 min ^-1 , 110 mol _H2 mol _atom ^-1 min ^-1 , 120 mol _H2 mol _atom ^-1 min ^-1 , 130 mol _H2 mol _atom ^-1 min ^-1 140 mol _H2 mol _atom ^-1 min ^-1 , 150 mol _H2 mol _atom ^-1 min ^-1 , 160 mol _H2 mol _atom ^-1 min ^-1 , 170 mol _H2 mol _atom ^-1 min ^{- It may be 1} or 180 mol _H2 mol _atom ^-1 min ^-1 , but is not limited thereto.

The catalyst complex may reduce the activation energy of the hydrogen generation reaction to 57.5 kJ/mol or less. For example, it may be 55 kJ/mol, 52.5 kJ/mol, 50 kJ/mol, or 47.5 kJ/mol, but is not limited thereto.

Since the catalyst composite has excellent thermal stability, catalyst activity may be maintained or improved without a change in the particle size of the nanoparticles even after heat treatment.

The hydrogen generation reaction refers to a reaction for generating _{hydrogen (H 2} ) through dehydrogenation of a chemical hydrogen storage material. Chemical hydrogen storage materials include solid or liquid organic compounds containing hydrogen, organic-inorganic complexes, etc. For example, hydrogenated materials such as methyl-cyclohexane (MCH), N-methylcarbazole, dibenzyltoluene, and ammonia borane It may be a compound, but is not limited thereto.

The hydrogen generation reaction may be a hydrolysis dehydrogenation reaction of ammonia borane. The hydrolysis and dehydrogenation reaction of ammonia borane using the catalyst complex may generate 3 moles of hydrogen per 1 mole of ammonia borane.

Hereinafter, embodiments of the present specification will be described in more detail. However, the following experimental results describe only representative experimental results among the above examples, and the scope and content of the present specification may not be construed as reduced or limited by the examples. Each effect of the various embodiments of the present specification not explicitly presented below will be specifically described in the corresponding section.

Examples 1-5: Synthesis of hydrogen production reaction catalyst

A hydrogen production catalyst G6-OH(Pt) _n (Pd) _180-n was synthesized as follows.

30:150, 60:120, 90:90, 120:60 or 150:30 aqueous solution of 100 mM K ₂ PtCl ₄ and 100 mM K _{2 PdCl 4} aqueous solution, respectively (Example 1, Example 2, Example 3, Example, respectively) (corresponding to Example 4 or Example 5) was added to an aqueous solution of 2 μM hydroxyl terminated 6th generation polyamidoamine dendrimer (G6-OH). The solution was stirred at room temperature for 72 hours ^{to complex Pt 2+} precursor ions and Pd ²⁺ precursor ions to the internal tertiary amine of G6-OH. Then, in a solution of Pt ²⁺ -Pd ²⁺ /G6-OH complex (ie, G6-OH(Pt ²⁺ ) _n (Pd ²⁺ ) _180-n ), the total molar equivalents of ^{Pt 2+} and Pd ²⁺ 10 times was added to an excess of 2 M NaBH ₄ solution and by keeping the solution under agitation for 24 hours in a sealed vial BH ₄ ^- the dendrimers reduced-encapsulated platinum-palladium nanoparticles _{(G6-OH (Pt) n} (Pd) _180-n ) solution. The resulting solution was dialyzed in distilled water for 24 hours using a nylon membrane filter (MWCO 12,000) to remove impurities, and dendrimer-encapsulated platinum-palladium nanoparticles (G6-OH(Pt) _n (Pd) _180-n ) were obtained.

Example 6: Synthesis of Hydrogen Generation Reaction Catalyst Complex

Hydrogen generation reaction catalyst complex G6-NH ₂ (Pt) ₉₀ (Pd) ₉₀ /GO was synthesized as follows.

HCl was added to 5 μM of an amine-terminated 6th generation polyamidoamine dendrimer (G6-NH ₂ ) aqueous solution to set the pH to 5.0 or less. After the G6-NH ₂ aqueous solution of pH 5.0 or less was added to _{100 mM K 2 PtCl 4 (Pt} 2+) and _{100 mM K 2 PdCl 4 (Pd} 2+) solution for each 90 equivalents of G6-NH _2, 76 It was stirred at room temperature for hours. _{A 2 M aqueous NaBH 4} solution corresponding to 20 equivalents of the total molar equivalents of Pt ²⁺ and Pd ²⁺ was added, and the pH was set to 7 or less using an aqueous HCl solution. Thereafter, Pt ²⁺ and Pd ²⁺ were reduced for 24 hours to generate a dendrimer-encapsulated platinum-palladium nanoparticle (G6-NH ₂ (Pt) ₉₀ (Pd) ₉₀ ) solution. The resulting solution was dialyzed (MWCO 12,000) in distilled water for 24 hours to remove impurities, and dendrimer-encapsulated platinum-palladium nanoparticles (G6-NH ₂ (Pt) ₉₀ (Pd) ₉₀ ) were obtained.

10 mL of an aqueous solution of 1 μM dendrimer-encapsulated platinum-palladium nanoparticles (G6-NH ₂ (Pt) ₉₀ (Pd) ₉₀ ) and 1.0 mg/mL of graphene oxide (Graphene Oxide, GO) containing 20 mM KOH After mixing 10 mL of aqueous solution, the mixture was stirred at 40 °C for 12 hours. Thereafter, the unreacted nanoparticles were removed by centrifugation at 12,000 rpm (14,811 x g) for 30 minutes, and the precipitated dendrimer-encapsulated platinum-palladium nanoparticles-graphene oxide complex (G6-NH ₂ (Pt) ₉₀ (Pd) ) ₉₀ /GO) was obtained and redispersed in 20 mL of distilled water.

Example 7: Synthesis of hydrogen production reaction catalyst complex

Hydrogen generation reaction catalyst complex G6-NH ₂ (Pt) ₅₅₀ /GO was synthesized by the following method.

HCl was added to an aqueous solution of 1 μM of an amine-terminated sixth-generation polyamidoamine dendrimer (G6-NH _{2 ) to set the pH to 5.0.} At this time, N ₂ purging was performed together, and N ₂ purging was continued until the reaction was finished. 10 mM Cu (NO ₃₎ equal to 50 equivalents of G6-NH ₂ in G6-NH ₂ aqueous solution of pH 5.0 was added to the _second aqueous solution, stirring and for 30 min N ₂ purging at room temperature for the copper ions inside the dendritic polymer ignited. A galvanic exchange reaction was induced by adding _{100 mM K 2} PtCl ₄ aqueous solution corresponding to 550 equivalents of G6-NH _{2 and immediately after adding 100 mM NaBH 4} aqueous solution, a reducing agent having the same equivalent as Pt. Thereafter, further stirring for 10 minutes resulted in a solution of dendrimer-encapsulated platinum nanoparticles (G6-NH ₂ (Pt) ₅₅₀ ). The resulting solution was dialyzed (MWCO 12,000) in a pH 3.0 solution to remove impurities, and dendrimer-encapsulated platinum nanoparticles (G6-NH ₂ (Pt) ₅₅₀ ) were obtained.

10 mL of acidic 1 μM aqueous solution of dendrimer-encapsulated platinum nanoparticles (G6-NH ₂ (Pt) ₅₅₀ ) and 1.0 mg/mL of aqueous solution of Graphene Oxide (GO) containing 20 mM KOH 10 After mixing mL, the mixture was stirred at 40 °C for 12 hours. Thereafter, the unreacted nanoparticles were removed by centrifugation at 12,000 rpm (14,811 x g) for 30 minutes, and the precipitated dendrimer-encapsulated platinum nanoparticles-graphene oxide complex (G6-NH ₂ (Pt) ₅₅₀ /GO) was It was obtained and redispersed in 20 mL of distilled water.

Comparative Examples 1-2

G6-OH(Pt) ₁₈₀ and G6-OH(Pd) ₁₈₀ were synthesized as follows.

180 molar equivalents of 100 mM K ₂ PtCl ₄ aqueous solution (Comparative Example 1) or 180 molar equivalents of 100 mM K ₂ PdCl ₄ aqueous solution (Comparative Example 2) were added to 2 μM 6th generation polyamidoamine dendrimer (G6-OH) aqueous solution. ^{The solution was stirred for 72 hours to complex Pt 2+} precursor ions or Pd ²⁺ precursor ions to the internal tertiary amine of G6-OH. Then, in a solution of Pt ²⁺ /G6-OH complex (G6-OH(Pt ²⁺ ) ₁₈₀ ) or Pd ²⁺ /G6-OH complex (G6-OH(Pd ²⁺ ) ₁₈₀ ) solution, a 10-fold excess of NaBH ₄ and was added and kept under stirring the solution 24 hours in a sealed vial BH ₄ ^- reduced dendritic polymer-encapsulated platinum nanoparticles _{(G6-OH (Pt) 180} ) or a dendritic polymer-encapsulated palladium nanoparticles (G6-OH (Pd ) ₁₈₀ ) solution. The resulting solution was dialyzed for 2 days using a nylon membrane filter to remove impurities, and dendrimer-encapsulated platinum nanoparticles (G6-OH(Pt) ₁₈₀ ) or dendrimer-encapsulated palladium nanoparticles (G6-OH(Pd) ₁₈₀ ) was obtained.

Comparative Example 3

A mixture of G6-OH(Pt) ₁₈₀ and G6-OH(Pd) ₁₈₀ was prepared as follows.

90 molar equivalents of each of K ₂ PtCl ₄ aqueous solution and K ₂ PdCl ₄ aqueous solution were mixed with an aqueous polyamidoamine dendrimer (G6-OH) solution _{, reduced with excess NaBH 4} , and dialyzed to dendrimer-encapsulated platinum nanoparticles (G6-OH (G6-OH) Pt) ₁₈₀ ) and dendrimer-encapsulated palladium nanoparticles (G6-OH(Pd) ₁₈₀ ) were obtained. Then, they were physically mixed to obtain a mixture of dendrimer-encapsulated platinum nanoparticles (G6-OH(Pt) ₁₈₀ ) and or dendrimer-encapsulated palladium nanoparticles (G6-OH(Pd) ₁₈₀ ).

Comparative Example 4

G6-NH ₂ (Pt) ₁₈₀ /GO was synthesized as follows.

HCl was added to a 10 μM amine-terminated 6th generation polyamidoamine dendrimer (G6-NH ₂ ) aqueous solution to set the pH to 5.0 or less. After adding _{100 mM K 2 PtCl 4 (Pt} 2+) aqueous solution in G6-NH ₂ aqueous solution of pH 5.0 or less for the 180 equivalent weight of G6-NH _2, it was stirred at room temperature for 76 hours. Then, _{2 M NaBH 4} aqueous solution corresponding to 20 equivalents of ^{Pt 2+} was added, and the pH was set to 7 or less using HCl aqueous solution. ^{Pt 2+} was reduced for 24 hours to give a solution of dendrimer-encapsulated platinum nanoparticles (G6-NH ₂ (Pt) ₁₈₀ ). The resulting solution was dialyzed (MWCO 12,000) in distilled water for 24 hours to remove impurities, and dendrimer-encapsulated platinum nanoparticles (G6-NH ₂ (Pt) ₁₈₀ ) were obtained.

10 mL of 1 μM dendrimer-encapsulated platinum nanoparticles (G6-NH ₂ (Pt) ₁₈₀ ) aqueous solution and 10 mL of 1.0 mg/mL graphene oxide (GO) aqueous solution containing 20 mM KOH were mixed. Then, the mixture was stirred at 40 °C for 12 hours. Thereafter, the unreacted dendrimer-encapsulated platinum nanoparticles were removed by centrifugation at 12,000 rpm (14,811 x g) for 30 minutes, and the precipitated dendrimer-encapsulated platinum nanoparticles-graphene oxide complex (G6-NH ₂ (Pt) ₁₈₀ /GO) was obtained and redispersed in 20 mL of distilled water.

Comparative Example 5

G6-NH ₂ (Pt) ₅₅₀ /CB was synthesized as follows.

After synthesizing dendrimer-encapsulated platinum nanoparticles (G6-NH ₂ (Pt) ₅₅₀ ) in the same manner as in Example 7, it was mixed with carbon black (CB, Vulcan®carbon) to dendrimer-encapsulated platinum nanoparticles. A particle-carbon black complex (G6-NH ₂ (Pt) ₅₅₀ /CB) was obtained.

Experimental Example 1: Analysis of the shape and particle size distribution of DENs

Examples 1 to 5 and Comparative Examples 1 to 2 dendrimer-encapsulated nanoparticles (dendrimer-encapsulated nanoparticles, DENs) to observe the shape and measure the size distribution, JEM-3010 driven at 300 kV (JEOL) was used to take a transmission electron microscope (TEM) image.

1 shows a TEM image and a particle size distribution histogram of the dendrimer-encapsulated nanoparticles of Examples 1-5 and Comparative Examples 1-2.

Referring to FIG. 1 , it can be seen that all of the dendrimer-encapsulated nanoparticles of different compositions are spherical and do not aggregate with each other to have a monodispersed average particle size of 1.65 to 1.75 nm.

Experimental Example 2: Analysis of component distribution of DENs

In order to confirm the component distribution of the dendrimer-encapsulated nanoparticles (DENs) of Example 3, elemental analysis was performed using an FEI Titan Themis 300 (Thermo Scientific) equipped with a Super-X EDS system operating at 300 kV. . EDS samples were prepared on 200 mesh nickel grids (Ted Pella Inc.) coated with carbon film.

2A is a high angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) image of the dendrimer-encapsulated nanoparticles of Example 3, and FIGS. 2B and 2C are Pt and Pd elements. STEM-energy dispersive X-ray spectroscopy elemental mapping images (STEM-EDS). FIG. 2D is a line profile analysis result along the line indicated on the single particle of FIG. 2A.

2, the dendrimer-encapsulated platinum-palladium nanoparticles according to an embodiment of the present invention are single particles in which platinum atoms and palladium atoms are uniformly distributed, but palladium has a relatively large tendency to be distributed in the center of the particles. can be checked

Experimental Example 3: Analysis of component ratio of DENs

To analyze the ratio of platinum (Pt) and palladium (Pd), which are components included in the dendrimer-encapsulated nanoparticles (DENs) of Examples 1 to 5 and Comparative Examples 1 to 2, Al Kα radiation (hv = 1486.6 eV) ) using a K-Alpha X-ray photoelectron spectrometer (Thermo Scientific) to obtain an X-ray photoelectron spectroscopy (XPS) spectrum. To correct for sample charging, the XPS peak position was referenced to C 1s at 284.4 eV. XPS samples were obtained by adding a few drops of aqueous DENs solution on a silicon wafer and then drying in air. Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis was performed using Optima 8300 (Perkin Elmer). For ICP-AES measurement, all samples were dissolved in aqua regia solution using TOPEX microwave sampler (PreeKem).

3 shows the XPS spectra of the dendrimer-encapsulated nanoparticles of Examples 1 to 5 and Comparative Examples 1 and 2, and FIG. 4 shows the XPS spectra in the Pt(4f) region and the Pd(3d) region.

5 is a result of measuring the content ratio of platinum and palladium with respect to the dendrimer-encapsulated platinum-palladium nanoparticles of Examples 1 to 5 using ICP-AES.

Table 1 below shows the ratios of Pt and Pd content inside the dendrimer-encapsulated nanoparticles of Examples 1 to 5 and Comparative Examples 1 and 2 calculated from XPS spectra, and compared with the theoretical ratios.

division atomic fraction Theoretical atomic fraction (%) Pt (%) Pd (%) Pt (%) Pd (%) Comparative Example 1: Pt ₁₈₀ 100 0 100 0 Example 1: Pt ₃₀ Pd ₁₅₀ 25.6±10.3 74.4±8.9 16.7 83.3 Example 2: Pt ₆₀ Pd ₁₂₀ 38.4±1.3 61.6±0.9 25 75 Example 3: Pt ₉₀ Pd ₉₀ 58.2±10.9 41.8±7.7 50 50 Example 4: Pt ₁₂₀ Pd ₆₀ 83.8±2.7 16.2±1.9 75 25 Example 5: Pt ₁₅₀ Pd ₃₀ 92.3±1.5 7.7±1.2 83.3 16.7 Comparative Example 2: Pd ₁₈₀ 0 100 0 100

3 and 4, the ratio of Pt and Pd inside each of the dendrimer-encapsulated nanoparticles can be confirmed, and Pt and Pd each show two pairs of peaks, so 6G-OH(Pt) _n (Pd) _180-n It can be seen that each metal atom is partially reduced to have two oxidation states (Pt ⁰ , Pt ²⁺ , Pd ⁰ , Pd ²⁺ ).

Referring to FIG. 5 and Table 1, the atomic fraction of Pt was relatively high and the atomic fraction of Pd was relatively low compared to the theoretically predicted values.

Experimental Example 4: Evaluation of catalytic activity of DENs

To investigate the catalytic action of _{ammonia borane (AB, NH 3} BH ₃ ) hydrolytic dehydrogenation, which changes according to the composition of platinum (Pt) and palladium (Pd) among dendrimer-encapsulated nanoparticles (DENs), The catalytic activity of the dendrimer-encapsulated nanoparticles of Examples 1 to 5 and Comparative Examples 1 to 3 was evaluated.

Hydrolytic dehydrogenation of AB was performed at 25 °C using a laboratory built-in dehydrogenation apparatus equipped with an Extech SDL700 manometer (Extech Instruments). 6 shows the dehydrogenation apparatus. The apparatus comprises a 100 mL three-necked round-bottom flask. The first neck of the flask was connected to the _{N 2} tank through a three-way stopcock made of glass. In addition, the second neck of the flask was attached to the dropping funnel used for reagent addition, and the third neck was sealed to a pressure transducer (Extech) so that the pressure of hydrogen gas was recorded in real time. Prior to the hydrolysis dehydrogenation reaction, 2 mL of 2 μM dendrimer-encapsulated nanoparticles prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were placed in a round-bottom flask containing a magnetic stir bar. The catalyst content was adjusted to a total of 400 nM. Then, the reaction system was _{purged with N 2} gas for 3 minutes. After confirming that the reaction temperature was kept constant at 25 °C, using a dropping funnel under vigorous stirring (1,200 rpm), 8 mL of an aqueous AB solution (31.25 mM) was added so that the AB content was 25 mM to hydrolyze AB. Dehydrogenation was initiated. The amount of hydrogen gas produced was measured by monitoring the pressure increase inside the flask between dehydrogenation reactions. The pressure of hydrogen gas was recorded every second in a measurable range up to 30 psi using a manometer connected to a PT30 pressure transducer (Extech Instruments).

Figure 7a shows the time-dependent hydrogen production from the AB aqueous solution of the dendrimer-encapsulated nanoparticles of Examples 1 to 5 and Comparative Examples 1 to 3, and Figure 7b is G6-OH (Pt) ₉₀ (Pd) _{90 of Example 3} and the time-dependent hydrogen generation from an AB aqueous solution of a physical mixture of G6-OH(Pt) ₁₈₀ and G6-OH(Pd) _{180 of Comparative Example 3.}

Referring to FIG. 7 , in the presence of dendrimer-encapsulated nanoparticles, hydrogen generation started immediately upon addition of AB to the experimental vessel, until 3 equivalents of hydrogen were generated per mole of AB (i.e., all of the added AB was removed). consumption) continued almost linearly. These results suggest that the dendrimer-encapsulated nanoparticles have very strong activity for the hydrolysis of AB. For example, catalytic hydrolysis of AB in the presence of G6-OH(Pt) ₉₀ (Pd) ₉₀ was completed within about 10 minutes (molar ratio of Pt+Pd atoms to AB=1.6×10 ⁻⁶ ).

The turnover frequency (TOF) of the hydrogen production reaction using the dendrimer-encapsulated nanoparticle catalyst was calculated from the initial rate of hydrogen production in the initial reaction section (that is, the section in which the conversion rate of AB is 0 to 33%).

8 shows the change in TOF value of the same size dendrimer-encapsulated nanoparticles of Examples 1-5 and Comparative Examples 1-2 as a function of Pt and Pd ratio. The unconnected points in FIG. 8 are data of Comparative Example 3, which is a physical mixture of _{G6-OH(Pt) 180} and G6-OH(Pd) _{180 .} The TOF value showed a strong dependence on the composition of Pt and Pd in nanoparticles of the same size.

Table 2 below shows the TOF values of the dendrimer-encapsulated nanoparticles of Examples 1 to 5 and Comparative Examples 1 to 3.

division Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 2 Comparative Example 3 Cat. Pt ₁₈₀ Pt ₃₀ Pd ₁₅₀ Pt ₆₀ Pd ₁₂₀ Pt ₉₀ Pd ₉₀ Pt ₁₂₀ Pd ₆₀ Pt ₁₅₀ Pd ₃₀ Pd ₁₈₀ Pt ₉₀ + Pd ₉₀ TOF 32.5±7.9 63.5±8.3 90.6±18.0 108.5±15.9 80.2±21.7 57.4±11.5 20.5±2.1 79.0±7.2

8 and Table 2, the catalyst of Example 3 containing nanoparticles of _{Pt 90} Pd ₉₀ showed the highest catalytic activity with a TOF value of _{108.5±15.9 mol H2} mol ^-1 _atom min ^{-1, which} It is an improvement over the catalyst of Comparative Example 3 having a TOF value of 79.0±7.2 mol _H2 mol ^-1 _atom min ^{-1 under the same composition and reaction conditions.} In addition, the catalyst of Comparative Example 1 containing _{Pt 180} as a single metal exhibited higher catalytic activity than the catalyst of Comparative Example 2 containing _{Pd 180 as a single metal, but Pt 60} Pd ₁₂₀ having a higher Pd content compared to Pt was used as a double metal It performed a double metallization, that is, these organic combination of example 2 of the catalyst embodiments comprising a Pt ₁₂₀ Pd ₆₀ is lower Pd content of Pt prepared by double metal exhibits a catalyst compared to a high catalyst activity in example 4, the platinum and the palladium atom, including the It can be seen that the catalytic activity can be improved by interacting with each other.

_{9A and Table 3 below show the calculation of activation energy (E a} ) when using the catalysts of Examples 1 to 5 and Comparative Examples 1 and 2 from the above-described hydrolysis reaction of AB, and FIG. It shows the rate constant K according to the temperature of the catalysts of Examples 1 to 5 and Comparative Examples 1 and 2 according to the Uss equation.

division Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 2 Cat. Pt ₁₈₀ Pt ₃₀ Pd ₁₅₀ Pt ₆₀ Pd ₁₂₀ Pt ₉₀ Pd ₉₀ Pt ₁₂₀ Pd ₆₀ Pt ₁₅₀ Pd ₃₀ Pd ₁₈₀ E _a 58.9±4.4 55.6±5.0 49.1±4.5 47.8±3.0 51.9±1.0 54.0±2.6 60.0±7.6

9 and Table 3, the catalyst of Example 3 shows the lowest activation energy at 47.8±3.0 kJ/mol, and the catalyst of Example 2 shows the next lowest activation energy at 49.1±4.5 kJ/mol. It exhibited a similar aspect to the above-described catalytic activity. However, the catalyst of Example 1 exhibited a higher TOF value compared to the catalyst of Example 5 and thus had excellent catalytic activity, but the activation energy of the catalyst of Example 5 was lower than that of the catalyst of Example 1. This may be because the interaction between Pt and Pd affects the number of contacts between the catalyst and the reactant.

Experimental Example 5: Measurement of lattice parameters of DENs

In order to measure the lattice parameters of the dendrimer-encapsulated nanoparticles of Example 3, high-resolution transmission electron microscopy (HRTEM) images were taken.

10 is an HRTEM image of the dendrimer-encapsulated nanoparticles of Example 3.

Referring to FIG. 10 , it can be seen that the lattice parameter of the dendrimer-encapsulated nanoparticles of Example 3 is 0.224 nm.

Experimental Example 6: Analysis of the shape and particle size distribution of DENs/GO

Observing the morphology of the dendrimer-encapsulated nanoparticles-graphene oxide complex (DENs/GO) of Examples 6-7 and Comparative Example 4, and measuring the size distribution of the dendrimer-encapsulated nanoparticles on graphene oxide For this purpose, UV-Vis absorption spectrum was measured, and a transmission electron microscope (TEM) image was taken using a JEM-3010 (JEOL) operated at 300 kV.

11a and 11b show the synthesis of dendrimer-encapsulated platinum nanoparticles (G6-NH ₂ (Pt) ₅₅₀ ) and dendrimer-encapsulated platinum nanoparticles-graphene oxide complex (G6-NH ₂ (Pt) ₅₅₀ /GO) of Example 7; The UV-Vis spectrum of the process is shown.

12A, 12B, and 12C are TEM images of the dendrimer-encapsulated nanoparticles-graphene oxide composites of Examples 6, 7, and Comparative Example 4, respectively, and dendrimer-encapsulated nanoparticles on graphene oxide It shows a histogram of the particle size distribution .

Table 4 below compares the particle size distribution measurement results of the dendrimer-encapsulated nanoparticles on the dendrimer-encapsulated nanoparticles-graphene oxide composite of Examples 6 to 7 and Comparative Example 4 with the theoretical particle size.

division Example 6 Example 7 Comparative Example 4 Particle size distribution measure 1.7 ± 0.2 nm 2.3 ± 0.4 nm 1.8 ± 0.3 nm theoretical granularity 1.7 nm 2.5 nm 1.8 nm

11, 12 and Table 4, the dendrimer-encapsulated nanoparticles are uniformly dispersed and fixed on the surface of the graphene oxide, and the size of the dendrimer-encapsulated nanoparticles even after the dendrimer-encapsulated nanoparticles-graphene oxide complex is formed. does not change and it can be confirmed that there is no difference from the theoretical particle size value.

Experimental Example 7: Evaluation of catalytic activity of DENs/GO

_{To investigate the catalytic action for hydrolysis and dehydrogenation of ammonia borane (ammonia borane, AB, NH 3} BH ₃ ), which changes depending on whether the dendrimer-encapsulated nanoparticles are supported with graphene oxide, the same method as in Experimental Example 4 was carried out Examples 6-7, and the dendrimer-encapsulated nanoparticles-graphene oxide complex of Comparative Example 4 and the dendrimer-encapsulated nanoparticles before the graphene oxide support were evaluated and compared. The molar ratio of Pt atoms to AB is 0.001 (Pt atom : AB = 25 μM : 25 mM).

13a, 13b, and 13c show the time-dependent hydrogen generation from the AB aqueous solution before and after graphene oxide loading of the dendrimer-encapsulated nanoparticles of Examples 6, 7, and Comparative Example 4, respectively, and FIG. 13D is the Example 6 , 7, and the dendrimer-encapsulated nanoparticle-graphene oxide complex of Comparative Example 4 is a graph comparing the time-dependent hydrogen generation from the AB aqueous solution.

13A to 13C, in the presence of the dendrimer-encapsulated nanoparticles-graphene oxide complex, hydrogen generation started immediately upon addition of AB to the experimental vessel, until 3 equivalents of hydrogen were produced per mole of AB ( That is, until all the added AB is consumed), it continued almost linearly. These results mean that the dendrimer-encapsulated nanoparticles-graphene oxide complex has a very strong activity for hydrolysis of AB.

AB hydrolysis in the presence of the dendrimer-encapsulated nanoparticles-graphene oxide complex proceeded at a faster rate than the dendrimer-encapsulated nanoparticles before graphene oxide support. This result means that a stronger catalytic activity is exhibited when the nanoparticles are supported on graphene oxide.

Referring to FIG. 13D , the dendrimer-encapsulated nanoparticles-graphene oxide composites of Examples 6 and 7 exhibited stronger catalytic activity than the dendrimer-encapsulated nanoparticles-graphene oxide composites of Comparative Example 4. These results indicate improved catalytic activity when Pt and Pd atoms are included in a double metal structure compared to the case where Pt is included as a single metal, and the higher the equivalent weight of the included metal nanoparticles, the better the catalytic activity. .

The turnover frequency (TOF) of the hydrogen production reaction using the dendrimer-encapsulated nanoparticle catalyst before and after the graphene oxide support is the initial reaction period (that is, the period in which the conversion rate of AB is 0 to 33%) in the initial stage of hydrogen production was calculated from the speed.

Figure 14 shows the change in turnover frequency (TOF) value of the dendrimer-encapsulated nanoparticles before and after the graphene oxide loading of Examples 6, 7, and Comparative Example 4.

Referring to FIG. 14 , the dendrimer-encapsulated nanoparticles-graphene oxide composite exhibited a higher TOF value than the dendrimer-encapsulated nanoparticles before graphene oxide support. This result means that a stronger catalytic activity is exhibited when the nanoparticles are supported on graphene oxide. In addition, the dendrimer-encapsulated nanoparticles-graphene oxide composites of Examples 6 and 7 exhibited stronger catalytic activity than the dendrimer-encapsulated nanoparticles-graphene oxide composites of Comparative Example 4. These results indicate improved catalytic activity when Pt and Pd atoms are included in a double metal structure compared to the case where Pt is included as a single metal, and the higher the equivalent weight of the included metal nanoparticles, the better the catalytic activity. .

Experimental Example 8: Evaluation of catalytic activity according to the type of carrier

In order to investigate the catalytic action for hydrolysis and dehydrogenation of _{ammonia borane (ammonia borane, AB, NH 3} BH ₃ ), which varies depending on the carrier type of the dendrimer-encapsulated nanoparticles, Example 7 in the same manner as in Experimental Example 4 and the catalytic activity of the dendrimer-encapsulated nanoparticle-carrier complex of Comparative Example 5 was evaluated. The molar ratio of Pt atoms to AB is 0.001 (Pt atom : AB = 25 μM : 25 mM).

15a and 15b are TEM images and particle size distribution histograms of dendrimer-encapsulated platinum nanoparticles (G6-NH ₂ (Pt) ₅₅₀ ) before loading, and FIG. 15c is a dendrimer-encapsulated platinum nanoparticle-carbon black composite of Comparative Example 5 ( TEM image of G6-NH ₂ (Pt) ₅₅₀ /CB).

16A and 16B are graphs comparing time-dependent hydrogen production and changes in turnover frequency (TOF) values of the dendrimer-encapsulated nanoparticles-carrier complexes of Example 7 and Comparative Example 5;

Referring to FIG. 16A , the catalytic hydrolysis of AB in the presence of the dendrimer-encapsulated nanoparticles-graphene oxide complex of Example 7 supported on graphene oxide (GO) is the dendrimer-encapsulated nanoparticle of Comparative Example 5 supported on carbon black. Hydrolysis proceeded at a faster rate than hydrolysis in the presence of a particle-carbon black complex. This result means that when the nanoparticles are supported on graphene oxide, stronger catalytic activity is exhibited than when carbon black is used as the catalyst carrier.

Referring to FIG. 16B , the dendrimer-encapsulated nanoparticles-graphene oxide composite of Example 7 showed a higher TOF value than the dendrimer-encapsulated nanoparticle-carbon black composite of Comparative Example 5. This result means that when the nanoparticles are supported on graphene oxide, stronger catalytic activity is exhibited than when carbon black is used as the catalyst carrier.

Experimental Example 9: Thermal stability evaluation of DENs/GO

In order to evaluate the thermal stability of the dendrimer-encapsulated nanoparticles-graphene oxide composite, the dendrimer-encapsulated nanoparticles-graphene oxide composite of Example 7 was treated at 60° C. or 95° C. for 12 hours, respectively, and then ammonia borane (ammonia). The catalytic action of borane, AB, NH ₃ BH ₃ ) on hydrolytic dehydrogenation was evaluated. A dendrimer-encapsulated nanoparticle-graphene oxide complex without heat treatment was used as a control. The molar ratio of Pt atoms to AB is 0.001 (Pt atom : AB = 25 μM : 25 mM).

Figure 17a is a graph comparing the time-dependent hydrogen generation according to the heat treatment of the dendrimer-encapsulated nanoparticles-graphene oxide composite of Example 7, and Figure 17b is the dendrimer-encapsulation nanoparticle-graphene oxide composite of Example 7 It is a graph comparing changes in turnover frequency (TOF) values according to heat treatment.

Referring to FIGS. 17A and 17B , it was confirmed that the catalytic activity of the dehydrogenation reaction of AB was maintained even after heat treatment at 60°C or 95°C. These results indicate that the dendrimer-encapsulated nanoparticles-graphene oxide composite exhibits thermal stability and can act as a catalyst even after heat treatment.

18 is a TEM image and a histogram of particle size distribution of the dendrimer-encapsulated nanoparticles-graphene oxide composite of Example 7 after heat treatment at 60° C. for 12 hours.

Referring to FIG. 18 , no change in the size of the dendrimer-encapsulated nanoparticles was observed even after heat treatment, thereby confirming that a stable structure was maintained.

The description of the present specification described above is for illustration, and those of ordinary skill in the art to which one aspect of the present specification belongs can easily transform it into other specific forms without changing the technical idea or essential features described in this specification. you will be able to understand Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and likewise components described as distributed may be implemented in a combined form.

The scope of the present specification is indicated by the following claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present specification.

Claims (20)

a dendrimer and nanoparticles encapsulated inside the dendrimer,
The nanoparticles are made of an alloy of platinum and palladium,
A hydrogen production reaction catalyst that reduces the activation energy of the hydrogen production reaction. According to claim 1,
The dendrimer is a hydroxyl-terminated polyamidoamine dendrimer, a hydrogen production catalyst. According to claim 1,
The total molar equivalent of the nanoparticle constituents is 16 to 1024 equivalents based on 1 equivalent of the dendrimer, the hydrogen generation reaction catalyst. According to claim 1,
The average particle size of the nanoparticles is 1.0 ~ 3.5 nm, a hydrogen production reaction catalyst. 5. The method of claim 4,
The average particle size of the nanoparticles is a monodisperse of 1.65 ~ 1.75 nm, a hydrogen production reaction catalyst. According to claim 1,
The molar ratio of the platinum and the palladium is 1-5: 5-1, respectively, the hydrogen generation reaction catalyst. 7. The method of claim 6,
The molar ratio of the platinum and the palladium is 1 to 2: 2 to 1, respectively, the hydrogen generation reaction catalyst. According to claim 1,
The turnover frequency (TOF) of the hydrogen generation reaction using the catalyst is 50 mol _H2 mol _atom ^-1 min ^-1 or more, the hydrogen generation reaction catalyst. According to claim 1,
The catalyst reduces the activation energy of the hydrogen production reaction to 57.5 kJ / mol or less, a hydrogen production reaction catalyst. 10. The method according to any one of claims 1 to 9,
The hydrogen production reaction is a hydrolysis dehydrogenation reaction of ammonia borane, a hydrogen production reaction catalyst. A carbon-based carrier and a catalyst supported on the carbon-based carrier,
The catalyst comprises a dendrimer and nanoparticles encapsulated inside the dendrimer,
The nanoparticles are made of platinum, palladium, or an alloy of platinum and palladium,
A hydrogen production catalyst complex that reduces the activation energy of the hydrogen production reaction. 12. The method of claim 11,
The dendrimer is an amine-terminated polyamidoamine dendrimer, the hydrogen generation reaction catalyst complex. 12. The method of claim 11,
The total molar equivalent of the nanoparticle constituents is 16 to 1024 equivalents based on 1 equivalent of the dendrimer, the hydrogen generation reaction catalyst complex. 12. The method of claim 11,
The average particle size of the nanoparticles is 1.0 ~ 3.5 nm, hydrogen production reaction catalyst complex. 12. The method of claim 11,
The carbon-based carrier is chemically processed graphene (CCGs), a hydrogen production reaction catalyst composite. 16. The method of claim 15,
The carbon-based carrier is graphene oxide or reduced graphene oxide, hydrogen production reaction catalyst complex. 12. The method of claim 11,
The molar ratio of platinum and palladium contained in the alloy is 1 to 2: 2 to 1, respectively, the hydrogen generation reaction catalyst composite. 12. The method of claim 11,
The turnover frequency (TOF) of the hydrogen generation reaction using the catalyst complex is 90 mol _H2 mol _atom ^-1 min ^-1 or more, the hydrogen generation reaction catalyst complex. 12. The method of claim 11,
The catalyst composite reduces the activation energy of the hydrogen production reaction to 57.5 kJ/mol or less, the hydrogen production reaction catalyst composite. 20. The method according to any one of claims 11 to 19,
The hydrogen production reaction is a hydrolysis dehydrogenation reaction of ammonia borane, a hydrogen production reaction catalyst complex.

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