KR20160000664A - Control of Catalytic Activity of Hybrid Nanocatalysts Using Surface Plasmons - Google Patents

Abstract

The present invention relates to a hybrid nanostructure catalytic system using a surface plasmon and, particularly, to a metal-insulation layer-metal nanostructure catalytic system. In addition, the present invention relates to a method for controlling catalytic activities of the nanostructure by using the surface plasmon and, more specifically, to catalytic activities for producing hot carriers (hot positive holes or hot electrons) from surface plasmon phenomena of a metal (2), and being controlled by passing the hot carriers through an insulation body and influencing catalytic activities of a metal (1), when exposing light to the metal (1)-insulation layer-metal (2) nanostructure.

Description

[0001] The present invention relates to a hybrid nanostructure,

The present invention relates to a hybrid nanostructure catalyst system using a surface plasmon, particularly a metal-insulator-metal nanostructure catalyst system, and also relates to a method for controlling the catalytic activity of the nanostructure using surface plasmon (Hot or hot electrons) are generated from the surface plasmon phenomenon of the metal 2 when light is applied to the metal (1) -insulating layer-metal (2) nanostructure, and these hot carriers To the catalytic activity controlled by affecting the catalytic activity of the metal (1) past the insulator.

Surface plasmons (SP) are collective charge density oscillations of electrons occurring on the surface of metal thin films, also called surface plasmon polarizations (SPPs) or plasmon surface polaritons (PSPs). Surface plasmons interact with light waves to excite and enhance the size of the incident light. As the surface plasmon moves away from the interface in the vertical direction, the plasmon resonance Thereby causing a phenomenon. The surface plasmon resonance phenomenon is localized surface localization observed in noble metals of about 10 - 200 nm thickness, noble metal in the form of smooth plate, propagating plasmons observed at the dielectric interface, and noble metal nanoparticles of 10 - 200 nm size. and plasmon resonance (LSPR). Research related to this surface plasmon phenomenon has been actively and widely applied recently with progress of nanoscience technology.

Semiconductor materials such as titanium dioxide have an energy band structure in which the highest energy band occupied by electrons in the semiconductor energy band is called the valence band and the lowest energy band that is not occupied by the electrons The energy gap is called a band gap energy, and the band gap energy has a value unique to each material. When such a semiconductor material is irradiated with light having energy larger than the band gap energy inherent to the semiconductor material, electrons are excited in the valence band to be transferred to the conduction band, and holes are formed in the valence band, The harmful substances in the surrounding are decomposed by the strong oxidation-reduction reaction. The bandgap energy present in the semiconductor material prevents the rapid recombination of electrons and holes induced in the valence band and conduction band, thereby extending the duration of the photochemical oxidation and reduction reaction. However, the semiconductor material (3.2 eV), such as titanium dioxide, which has a large bandgap absorbs light of a short wavelength corresponding to a wavelength of less than 400 nm, and thus has a disadvantage that it can not absorb visible light, have.

In order to overcome such disadvantages, in recent years, studies for hybridizing a material of heterogeneous components to titanium dioxide have been actively conducted. The metal / TiO ₂ hybrid nano-materialization technique of a heterogeneous structure in which a noble metal is introduced is one of the best known methods. Composite materials composed of different metal / semiconductor components such as metal / titanium oxide are known to exhibit improved properties due to their superior physical properties due to the surface plasmon effect of metal components and the like, which do not have single component titanium oxide. Materials, photocatalysts, sensors, and the like.

As described above, by introducing the noble metal nanoparticles into the mono-component titanium dioxide in recent years, and by having the photocatalytic activity further improved owing to the induction effect of the surface plasmon properties of these components (Korean Patent Application Laid-Open No. 10-2010-0022323 , Korean Patent Application Laid-Open No. 10-2014-0036089, Korean Patent Application Laid-Open No. 10-2011-0097253, etc.), attempts have been made to expand the absorbance to the visible light range, but titanium dioxide catalyst Which is difficult to manufacture. In particular, a metal catalyst structure composed of a single metal exhibiting the characteristics of surface plasmons disappears within a short time even though hot carriers (hot holes or hot electrons) generated by the metal surface plasmon phenomenon are generated under the absorption of light, It can not be used effectively in the reaction.

On the other hand, the present inventors have found that hot carriers (hot holes or hot electrons) generated in the metal-insulator-metal nanostructure such as the present invention can survive for a long time due to the insulating layer existing between the metal and the metal , Which has been found to be able to intervene in the catalytic reaction. That is, by introducing an insulating layer between the metal and the metal, the present inventors have been able to maximize the efficiency of the catalytic reaction by overcoming the problem that the hot carriers in the existing catalyst disappear within a short time.

That is, the present inventors have developed a metal-insulator-metal nanostructure catalyst system using a surface plasmon magnified to a visible light range in order to compensate for the disadvantages and maximize solar energy conversion, A method for controlling the catalytic activity of the insulating layer-metal nanostructures has been developed.

It is an object of the present invention to provide a metal-insulator-metal nanostructure catalyst system using surface plasmons and to provide a method of controlling the catalytic activity of the nanostructure using surface plasmons, To maximize the conversion to energy.

In order to achieve the above object, the present invention provides a metal-insulator-metal nanostructure catalyst system using surface plasmon.

The present invention also provides a method of controlling the catalytic activity of a metal-insulator-metal nanostructure using a surface plasmon.

In one embodiment of the present invention, the metal-insulator-metal nanostructure may be a metal-insulator-metal layer deposited on a substrate.

In one embodiment of the present invention, the metal-insulator-metal nanostructure catalyst system is a metal (1) -insulating-metal (2) nanostructure catalyst system, the metal (2) is a plasmon- , The insulating layer is an oxide insulating thin film, and the metal (1) may be a catalytic material.

In one embodiment of the present invention, the plasmon generating nanostructure may be gold (Au), silver (Ag), or aluminum (Al).

In one embodiment of the present invention, the oxide insulator thin film is _{CeO 2, Nb 2 O 5,} TaO 5, SiO 2, Al 2 O 3, Co 3 O 4, MnO 2, Fe 2 O 3 or TiO ₂ days have.

In an embodiment of the present invention, the catalytic material is selected from the group consisting of Au, Ag, Pt, Co, Ni, Pd, Al, Fe) or iridium (Ir).

In one embodiment of the present invention, the plasmon generating nanostructure may be a metal nano-island, a metal nanowire, or a metal nanopatterned structure.

In one embodiment of the present invention, the oxide insulating thin film may be Al ₂ O ₃ or TiO ₂ .

In one embodiment of the present invention, the catalyst material may be platinum (Pt).

In one embodiment of the present invention, the metal-insulator-metal nanostructure catalyst system may be one used for CO oxidation.

The present invention relates to a hybrid nanostructure catalyst system using a surface plasmon, particularly to a metal-insulator-metal nanostructure catalyst system, and also to a method for controlling the catalytic activity of the nanostructure using surface plasmon, (Hot hole or hot electron) is generated from the surface plasmon phenomenon of the metal (2) when light is applied to the nanostructure, and the hot carriers pass through the insulator 1). ≪ / RTI > The great advantage of controlling nanocatalyst activity using these plasmon phenomena is the maximization of solar energy conversion. That is, since the plasmon phenomenon of metal occurs mainly in the visible light region of solar energy, the present invention has an effect of converting the energy corresponding to this region into useful chemical energy.

Since the metal catalyst structure composed of a single metal showing the characteristics of surface plasmons disappears within a short time even though hot carriers (hot holes or hot electrons) generated by the metal surface plasmon phenomenon are generated under the absorption of light, It can not be used effectively. On the other hand, the hot carriers (hot holes or hot electrons) generated in the metal-insulator-metal nanostructure can survive for a long time due to the insulating layer present between the metal and the metal, . That is, by introducing an insulating layer between the metal and the metal, the present inventors have been able to maximize the efficiency of the catalytic reaction by overcoming the problem that the hot carriers in the existing catalyst disappear within a short time.

FIG. 1 illustrates a basic concept of a novel hybrid nano catalyst for controlling the activity of a nanocatalyst using (a) a surface plasmon; FIG. (B) and (c) illustrate the examples, wherein the nanocatalyst is composed of a metal nanostructure, an oxide insulating thin film, and a catalyst material (thin film or nanomaterial) for plasmon generation.
FIG. 2 is a graph showing the relationship between the surface plasmon and the surface plasmon in a metal-insulator-metal (MIM) nanostructure made of platinum nanoparticle (catalyst) -Al ₂ O ₃ or TiO ₂ (insulating layer) -Al, Ag or Au (surface plasmon mediator) And the catalytic activity is affected by the hot electrons generated by the platinum nanoparticles reaching the platinum nanoparticles.
FIG. 3 shows the fabrication of metal-insulator-metal (MIM) nanostructures comprising (a) platinum nanoparticles (catalyst) -Al ₂ O ₃ or TiO ₂ (insulating layer) -Al, Ag or Au (surface plasmon mediator) process; And (b) EDS mapping results for Pt / 2 nm TiO ₂ / Au nanostructures.
FIG. 4 shows the results of CO oxidation performed to identify the role of hot electrons generated by surface plasmons on surface chemistry in various MIM nanostructures: (a) TiO ₂ as an insulating layer, (b) ) is Al ₂ O ₃ is used as an insulating layer.

The present invention relates to catalytic activity controlled by metal surface plasmon phenomena in a metal-insulator-metal nanostructure, wherein the metal (1), the insulating layer and the metal (2) (Hot holes or hot electrons) are generated from the surface plasmon phenomenon of the metal 1, and these hot carriers influence the catalytic activity of the metal 1 through the insulator. The great advantage of controlling nanocatalyst activity using these plasmon phenomena is the maximization of solar energy conversion. That is, since the plasmon phenomenon of metal occurs mainly in the visible light region of solar energy, the present invention has an effect of converting the energy corresponding to this region into useful chemical energy.

The surface plasmon phenomenon used in the present invention is explained by the following mechanism. That is, there are free electrons in the metal, which is a conductor, and the free electrons are not bound to metal atoms, so they are likely to respond to specific external stimuli. Particularly, when the metal is nano-sized, surface plasmon properties are exhibited by the behavior of free electrons and have unique optical properties. The resonance phenomenon by the surface plasmon is a phenomenon that free electrons on the metal surface are collectively vibrated due to the resonance of the electromagnetic field of the specific energy possessed by light when light is incident between the surface of the metal nano particle as a conductor and the dielectric. Therefore, the metal nanoparticles in which surface plasmons are generated strongly resonate with light of various wavelengths depending on the kind, shape and size of the metal, and amplify light absorption or scattering. Further, in order to absorb the incident light and to amplify the scattering, a strong charge transfer and an energy transfer phenomenon occur internally.

FIG. 1 shows the structure of a novel hybrid catalyst (or hybrid nano catalyst) for controlling the activity of a nanocatalyst using the above-described surface plasmon.

The hybrid catalyst of the present invention comprises a plasmon generating nanostructure, an oxide insulator thin film, and a catalyst material.

According to one embodiment, the hybrid catalyst of the present invention further comprises a substrate, which is composed of a substrate, a plasmon generating nanostructure, an oxide insulating thin film, and a catalytic material, and the plasmon generating nanostructure, the oxide insulating thin film, And catalytic material may be deposited in sequence.

When light is absorbed into the hybrid catalyst of the present invention, a hot carrier (hot hole or hot electron) is generated by the plasmon phenomenon in the plasmon generating nanostructure, and the hot carrier is injected into the catalyst material through the oxide insulator.

The term "hybrid catalyst" according to the present invention is used in combination with "hybrid nanocatalyst", "metal-insulator-metal nanostructure", "metal-insulator-metal nanostructure catalyst system", "MIM nanostructure" .

The term "plasmon generating nanostructure" according to the present invention can be used in combination with "plasmon generating metal nanostructure" or "surface plasmon mediator ".

The "plasmon generating nanostructure" of the present invention includes, but is not limited to, metal nano-islands, metal nanowires, and metal nanopatterned structures.

The metal of the "plasmon generating nanostructure" of the present invention may be selected from gold (Au), silver (Ag), or aluminum (Al), but is not limited thereto.

The term "oxide insulating thin film " according to the present invention can be used in combination with" oxide thin film "," oxide thin film "," thin film "," insulating layer "," insulating layer thin film "or" insulator thin film "

The "oxide insulating thin film" of the present invention is at least one oxide selected from the group consisting of CeO ₂ , Nb ₂ O ₅ , TaO ₅ , SiO ₂ , Al ₂ O ₃ , Co ₃ O ₄ , MnO ₂ , Fe ₂ O ₃ and TiO ₂ may be selected, preferably, Al ₂ O ₃ or TiO ₂ or, and the like.

The thickness of the "oxide insulating thin film" of the present invention should be very thin for electrons to pass through, preferably 0.5 nm to 10 nm in thickness.

The "catalytic material" of the present invention includes at least one of gold (Au), silver (Ag), platinum (Pt), cobalt (Co), nickel (Ni), palladium (Pd), aluminum (Al) Ir), preferably platinum (Pt), but not limited thereto.

The "catalytic material" of the present invention may be in the form of various catalyst nanoparticles or thin films.

The nanocatalyst of the present invention is preferably particles having a size of 1 to 20 nm. When the size of the metal particles is less than 1 nm, there is a problem that the metal particle layer is not formed well. When the size of the metal particles is more than 20 nm, the surface area of the metal particles is decreased. The nanocatalyst of the present invention is more preferably 2 to 10 nm, even more preferably 2.5 to 5 nm.

"Substrate" which may be included in the present invention including, SiO _2, but is not limited to this.

The "hybrid catalyst" of the present invention can be used for CO oxidation, H ₂ oxidation, ethylene hydrogenation and water gas shift reaction, .

2 is more specifically "platinum nano-particles (catalyst) -Al ₂ O ₃ or TiO ₂ (insulating layer) -Al, Ag or Au (surface plasmon medium)" in the Metal-Insulator-Metal (MIM) nanostructure consisting of A conceptual diagram of a process in which hot electrons generated by surface plasmons reach the platinum nanoparticles and affect the catalytic activity. In this conceptual diagram, noble metals such as Al, Ag, or Au were used as the surface plasmon source, TiO ₂ or Al ₂ O ₃ was used as the insulating layer, and platinum nanoparticles were used as the catalytic material. The key element of the MIM structure is an insulating layer which forms a barrier between the metal and the metal while efficiently moving the hot electrons generated from the metal by the metal surface plasmons to the platinum particles and back to the metal surface It plays a role of making it disappear.

The hot electrons generated in the MIM structure and the surface chemical reaction mechanism of the hot electrons will be described in detail. First, hot electrons are generated by the surface plasmon from the metal when the light energy is given. The generated hot electrons are first tunneled, Mechanism, and second, through the schottky emission mechanism, to the various reactions occurring on the surface of the platinum nanoparticles, especially the CO oxidation, reaching the platinum nanoparticles.

A detailed description of the tunneling mechanism and the Schottky discharge mechanism is as follows: First, from the viewpoint of classical mechanics, particles (electrons or holes) can not exceed energy barriers having higher energy than their own. However, from the viewpoint of quantum mechanics, when an insulator or a vacuum is present between two metals or semiconductors, an energy barrier exists. When the thickness of the energy barrier is small, particles (electrons or holes) do. This is often referred to as the tunneling effect. When the hot carriers generated by the metal plasmon phenomenon in the metal-insulator-metal nanostructure of the present invention have an energy level lower than the energy barrier existing between the two metals, the hot carriers can pass through the tunneling mechanism, As shown in FIG. When a metal and a semiconductor are brought into contact with each other, a schottky barrier, which is an energy barrier, is formed. Hot carriers generated by the metal surface plasmon phenomenon to cross this energy barrier must have a high energy level and only hot carriers having energy levels higher than this energy barrier can reach the metal catalyst material through the Schottky exhaust mechanism .

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these examples are for illustrative purposes only and that the scope of the present invention is not construed as being limited by these examples.

Example

[Example 1] "Platinum nanoparticle (catalyst) -Al ₂ O ₃  Or TiO ₂ (Insulator-Metal) Insulator-Metal (MIM) nanostructure consisting of Al, Ag or Au (surface plasmon mediator)

FIG. 3 shows a manufacturing process of a metal-insulator-metal (MIM) nanostructure composed of "platinum nanoparticle (catalyst) -Al ₂ O ₃ or TiO ₂ (insulating layer) -Al, Ag or Au (surface plasmon mediator) .

More specifically, as shown in FIG. 3 (a), silica (SiO ₂ ) nanoparticles are first arrayed into a single layer by the Langmuir-Blodgett technique. The Langmuir-Blotting technique is based on the property that molecules are arranged in a specific direction in water and organic layer by making one molecule organic and water soluble on the other. It has the advantage of being able to make thin films of organic molecules of several nm thickness.

Thereafter, a surface plasmon mediator, a metal, is deposited thereon by electron beam evaporation (E-beam evaporation). Thereafter, the silica nanoparticles are removed to obtain a single layer of metal having a pattern, and an insulating layer is deposited on the single metal layer through atomic layer deposition (ALD). Finally, platinum nanoparticles are deposited on the structure as a catalytic material by the Langmuir-Blodgett technique.

The metal-insulator-metal nanostructure fabricated through this procedure has a triangular and rectangular nano-islands shape having a roughly patterned shape, and these nano-islands have a size distribution of approximately 20 nm to 100 nm.

Hereinafter, a method for producing a metal-insulator-metal (MIM) nanostructure made of "platinum nanoparticle (catalyst) -Al ₂ O ₃ or TiO ₂ (insulating layer) -Al, Ag or Au (surface plasmon mediator) And more specifically.

<Example 1-1> Synthesis of silica nanoparticles and preparation of single molecule layer of silica nanoparticles

Chemicals. Tetraethyl orthosilicate (TEOS, 99.0 +%) and sodium dodecyl sulfate (SDS, 99.0 +%) were purchased from Sigma-Aldrich. Ammonium hydroxide (NH ₄ OH, 25.0 - 28.0%) was purchased from Daejung chemicals and Chloroform (min. 99.0%) was purchased from Junsei and was dissolved in absolute ethanol (EtOH) ) Was purchased from Merck. All the above-mentioned chemicals were used without further purification.

Silica spheres were synthesized by the modified Stover method. Briefly, 0.55 ml of NH ₄ OH in 3.5 ml of deionized water was mixed with 10 ml of EtOH to synthesize 200 nm size silica, and the mixture was maintained under magnetic stirring. 2.3 ml of TEOS in 10 ml of EtOH solution was added dropwise to the reaction mixture. After stirring the mixture for 8 hours, the reaction mixture was centrifuged at 3000 rpm for 10 minutes and washed with ethanol to obtain the silica spheres. The washing process was performed three times, and the spheres were further dispersed in methanol. By considering 3.29 ml of deionized water and keeping the concentration of all other reagents the same, we have obtained silica spheres with an average size of 200 nm. A single layer of the prepared silica spheres was deposited at room temperature using a Langmuir-Blodgett (LB) technique (Nima Technology 311D). Considering the diffusion of the Langmuir-Blodgett (LB trough) of silica spheres into the water subphase, 3 mg of SDS was added to the silacar dispersed in 2 ml of MeOH. After 45 minutes of ultra-sonication with heating, 3 ml of chloroform was mixed and sonicated for another 30 minutes. The prepared sample was then diffused onto the water surface and the surface pressure was monitored by the Wilhelmy plate method. The target surface pressure was maintained at 15 mN / m, and the spheres close to each other were moved onto the dipped silicon substrate by slowly raising the substrate at a rate of 1 mm / min.

Example 1-2: Deposition of plasmon metal by electron beam evaporation technique

Electron beam evaporation was used to deposit a fine metal film with a controlled thickness. As a first step in the fabrication of the metal (M1) -insulating layer-metal (M2) structure, three different metals 50 nm thick, aluminum (Al), silver (Ag), and gold (Au) Lt; / RTI &gt; The deposition was carried out at a temperature of 30 ± 2 ℃ to 10 KV DC voltage, the start pressure is 2.0 x 10 ^-6 Torr was last pressure was 1 ~ 3 x 10 ^-5 Torr. Typical deposition rates achievable with typical parameters are 1 Å / sec. While metal deposition is evident on the prepared silica monolayer substrate, the silica nanospheres act as masks. Following the metal deposition, the silica mask was removed by ultrasonication of the sample for a few minutes (1-2 minutes) to obtain a metal triangle.

Example 1-3: Deposition of an insulating layer by atomic layer deposition

The insulating layer of the MIM nanostructure can be fabricated by different methods including sputter oxidation, vapor deposition, thermal oxidation, anodic oxidation, electron beam evaporation and atomic layer deposition. have. Among these methods, atomic layer deposition is evaluated as the best method of providing a constant, pinhole-free ultrafine oxide layer. This highly adjustable deposition method is a highly compatible method for the fabrication of insulating layers of MIM nanostructures. Here, titanium dioxide (TiO ₂ ) and alumina (Al ₂ O ₃ ) were selected as the insulating layer. Tetrakis-dimethyl-amido titanium (TDMAT, UP chemical) as a titanium precursor and H ₂ O as a second reaction precursor were used for TiO ₂ deposition. 2 nm, 3 nm, 4 nm and 5 nm thick TiO ₂ were deposited at an average deposition rate of 0.7 A / cycle. Similarly, trimethyl aluminum (TMA) and H ₂ O were used as precursors for the deposition of alumina. With an average deposition rate of 1.1 A / cycle, with various thicknesses: 2 nm, 3 nm, 4 nm and 5 nm. With H ₂ and Ar gas mixture as carrier gas, all deposition was carried out at 150 ° C.

Example 1-4 Synthesis of Platinum Nanoparticles as Catalyst Materials and Preparation of Single-Dimensional Two-Dimensional Molecular Layer Using Langmuir-Blotting Technique

The final metal (M1) deposited on the insulator material is platinum nanoparticles ~ 4.3 nm. 4.3 nm Pt nanoparticles were synthesized by Tsung et al. (JACS, 131 (16), 5816-5822 (2009)). Here, the size of the Pt nanocrystals was measured by adjusting the concentration ratio of Pt (II) to Pt (IV) in the initial solution. Because the oxidation state of the metal ion precursor affects the ratio of the Pt precursor and consequently the number of nuclei. 20 mg of ammonium tetrachloroplatinate (II) (NH ₄ ) ₂ PtCl ₆ ), 100 mg of PVP and 120 mg of tetramethylammonium bromide (N ⁺ (CH ₃ ) ₄ Br ^- ) was dissolved in 10 ml of ethylene glycol in a 25 ml round bottom flask at room temperature. The mixed solution was heated to 453 K in a silicone oil bath and kept under argon protection and magnetic stirring for 20 minutes, resulting in a dark brown solution. After the reaction, the solution was cooled to room temperature. Then, the method of depositing Pt nanoparticles by LB is similar to that mentioned above. The diffused solution was prepared by mixing Pt nanoparticles dispersed in chloroform and EtOH in a volume ratio of 1: 2. The target surface pressure was maintained at 15 mN / m.

[Example 2] EDS mapping results of the prepared MIM nanostructures

FIG. 3 (b) shows an EDS mapping result for a Pt / 2 nm TiO ₂ / Au nanostructure. From this, it is possible to directly confirm the position of each constituent element constituting the metal-insulator-metal nano structure. Platinum nanoparticles, the catalytic material, are found at the top of the nanostructure, and Ti and O, which demonstrate the presence of the TiO ₂ layer used as the insulating layer between the platinum nanoparticles and Au at the intermediate location, are clearly identified And the existence of Au as a surface plasmon supply source was confirmed in the innermost part of the nanostructure.

[Example 3] CO oxidation reaction proceeded from the prepared MIM nanostructure

A study of the CO oxidation reaction was carried out in a batch reaction system under 40 Torr CO, 100 Torr O ₂ , and 620 Torr He. The gases were circulated along the reaction line by a Metal Bellows recirculation pump. A gas chromatograph with a thermal conductivity detector and a 6''1 / 8 '' SS molecular sieve 5A were used to separate the constituents for analysis. The measured reaction rates are expressed as turnover frequencies (TOF), which are measured as CO ₂ molecules generated per metal surface site per reaction time per second. At this time, the present inventors obtained all the reaction data by measuring the rate of CO oxidation reaction at a low conversion (i.e., less than ~ 20% conversion) under the kinematically controlled conditions, assuming different reaction conditions . The number of metal sites was calculated geometrically based on the results of scanning electron microscopy (SEM) measurements of the surface area of the patterned MIM nanostructure arrays. A halogen lamp (Dolhan-Janner D150) was used as a light source for measuring the catalytic activity under light irradiation. The light intensity was measured as 49.4 mW / cm ² by an optical power meter (ADCMT 8230) as the distance between the sample and the halogen lamp ~ 8 cm away.

FIG. 4 shows the results of CO oxidation performed to identify the role of hot electrons generated by surface plasmons on the surface chemistry in the MIM nanostructure of the present invention. As a result, the MIM nanostructures exhibited an increase in catalytic activity of about 50-100% under the condition of incidence of light, though they differ depending on the types of MIM nanostructures. This is because the surface plasmons induced by the absorption of light energy into the metal effectively generate hot carriers and the hot carriers are injected into the platinum nanoparticles through the insulating layer through a tunneling or schottky emission mechanism And it is thought that it affects catalytic activity.

Therefore, based on the above results, it can be concluded that the hot carrier generated by the surface plasmon generated during the incident light affects the catalytic activity of the CO oxidation reaction.

The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

Claims (20)

Metal-Insulator-Metal nanostructure catalyst system using surface plasmon. The method according to claim 1,
Wherein the metal-insulator-metal nanostructure catalyst system is one in which a metal-insulator-metal is sequentially deposited on a substrate. 3. The method according to claim 1 or 2,
Wherein the metal-insulator-metal nanostructure catalyst system is a metal (1) -insulating-metal (2) nanostructure catalyst system, the metal (2) is a plasmonic nanostructure, the insulator layer is an oxide insulator thin film , And the metal (1) is a catalytic material. The method of claim 3,
Wherein the plasmon generating nanostructure is gold (Au), silver (Ag), or aluminum (Al). The method of claim 3,
The oxide insulator thin film is _{CeO 2, Nb 2 O 5,} TaO 5, SiO 2, Al 2 O 3, Co 3 O 4, MnO 2, Fe 2 O 3 or a catalyst system, characterized in that TiO _2. The method of claim 3,
The catalyst material may be one selected from the group consisting of Au, Ag, Pt, Co, Ni, Pd, Al, Fe, Characterized by a catalytic system. The method of claim 3,
Wherein the plasmon generating nanostructure is a metal nano-island, a metal nanowire, or a metal nanopatterned structure. 6. The method of claim 5,
Wherein the oxide insulator thin film is Al ₂ O ₃ or TiO ₂ . The method according to claim 6,
Wherein the catalyst material is platinum (Pt). 3. The method according to claim 1 or 2,
Wherein the catalyst system is used in a CO oxidation reaction. A method for controlling catalytic activity of a metal-insulator-metal nanostructure using surface plasmon. 12. The method of claim 11,
Wherein the metal-insulator-metal nano-structure is formed by sequentially depositing a metal-insulator-metal layer on a substrate. 13. The method according to claim 11 or 12,
Wherein the metal-insulator-metal nano structure is a metal (1) -insulating layer-metal (2) nano structure, the metal (2) is a plasmon generating nano structure, the insulating layer is an oxide insulator thin film, 1) is a catalytic material. 14. The method of claim 13,
Wherein the plasmon generating nanostructure is gold (Au), silver (Ag), or aluminum (Al). 14. The method of claim 13,
The oxide insulator thin film is _{CeO 2, Nb 2 O 5,} TaO 5, SiO 2, Al 2 O 3, Co 3 O 4, MnO 2, Fe 2 O 3 or a method which is characterized in that the TiO _2. 14. The method of claim 13,
The catalyst material may be one selected from the group consisting of Au, Ag, Pt, Co, Ni, Pd, Al, Fe, Lt; / RTI &gt; 14. The method of claim 13,
Wherein the plasmon generating nanostructure is a metal nano-island, a metal nanowire, or a metal nanopatterned structure. 16. The method of claim 15,
Wherein the oxide insulator thin film is Al ₂ O ₃ or TiO ₂ . 17. The method of claim 16,
Wherein the catalytic material is platinum (Pt). 13. The method according to claim 11 or 12,
Wherein the method controls the catalytic activity of the metal-insulator-metal nanostructure in a CO oxidation reaction.

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