KR101206870B1 - Ring Type Palladium Nano Structure Body And The Palladium Nano Structure Photocatalyst For Photocatalytic Decomposition Of Water Thereof - Google Patents

Abstract

The present invention relates to a cyclic Pd nanostructure and a Pd nanostructure catalyst for water photolysis thereof. More specifically, the present invention relates to a cyclic Pd nanostructure comprising a cyclic Pd nanostructure reassembled cubic Pd nanoparticles by adjusting the pH in the range of 6 to 10 and a Pd nanostructure catalyst for water photolysis thereof.

According to the present invention, the high energy and surface area of the nanostructure itself, the chemical properties of the physical properties can be controlled, and due to the unique action of the nanostructured material, it is a very stable material. Excellent effect in the field. In addition, the nanostructures can be easily formed at room temperature and atmospheric pressure, which is low energy, so that high-purity ultra-precision Pd nanostructures can be produced.

Nano, Catalyst, Hydrogen, Cyclic Pd Nanostructure, Water Photolysis, Oxygen

Description

Ring type Palladium Nano Structure Body And The Palladium Nano Structure Photocatalyst For Photocatalytic Decomposition Of Water Thereof}

The present invention relates to a cyclic Pd nanostructure reassembled cubic Pd nanoparticles by adjusting pH and a Pd nanostructure catalyst for water photolysis thereof.

Research into the application of shape-controlled nanoparticles as a catalyst is still in its infancy and proof of concept.

In addition, the technology to mass-produce high-purity shape-controlled nanoparticles is indispensable, but the synthesis is difficult and the reproducibility is lacking.

Accordingly, the present invention can be used as a photocatalyst capable of producing hydrogen by photolysis of water by mass-producing a cyclic Pd nanostructure in which the shape of high purity is controlled.

The present invention provides a cyclic Pd nanostructure reassembled cubic Pd nanoparticles by adjusting the pH in the range of 6 ~ 10.

The present invention also provides a cyclic Pd nanostructure, characterized in that the cyclic Pd nanostructure is used as a Pd nanostructure catalyst for water photolysis in a water pollution emission suppression or prevention facility.

The present invention also provides a Pd nanostructure catalyst for water photolysis comprising the cyclic Pd nanostructure.

As described above, the cyclic Pd nanostructure has a high energy and surface area of the structure itself, can control chemical properties physically, and is a structurally very stable material. Excellent effect in various fields such as applications.

In addition, the nanostructures can be easily formed at room temperature and atmospheric pressure, which is low energy, so that high-purity ultra-precision Pd nanostructures can be produced.

The present invention is a cyclic Pd nanostructure reassembled cubic Pd nanoparticles by adjusting the pH in the range of 6 ~ 10 as a structure in which the Pd nanoparticles shape-controlled to a particle size of 1 ~ 30nm is reassembled and the distance between the unit particles To form a cyclic Pd nanostructure.

That is, the present invention provides a cyclic Pd nanostructure reassembled cubic Pd nanoparticles by adjusting the pH in the range of 6 ~ 10.

The pH adjustment is a hydrogen ion (H ⁺⁾ and hydroxide ions (OH ^-) to adjust the voltage and current, the pH is adjusted as to control the amount of.

At this time, the current is in the range of 0.01A ~ 10A, the voltage is 2V ~ 40V.

Here, the cyclic Pd nanostructure is formed by reassembling the cubic Pd nanoparticles by adjusting the pH in the range of 6 ~ 10.

At this time, the cubic Pd nanoparticles are those whose shape is controlled to a particle size of 1 ~ 30nm.

Here, the present invention is a technique for forming a cyclic Pd nanostructure by controlling the shape of the Pd nanoparticles during the molecular reassembly process while making the Pd metal nanoparticle-sized Pd nanoparticles. In this method, the cyclic Pd nanostructure is prepared by controlling the rate of reduction by adjusting the direction and rate of crystal growth of Pd nanometal to pH.

1 to 30nm cubic Pd nanoparticles and Pd nanostructure manufacturing method of the present invention by using the Pd rod electrolysis in the electrolyte to produce 100% pure Pd nanoparticles of 1 ~ 30nm cubic nanoparticles, Pd nanoparticles produced by adjusting the hydrogen ion concentration is to produce a cyclic Pd structure having a size of 10 ~ 300nm in which a certain shape that is self-assembled, that is, a ring shape is controlled.

Each Pd nanoparticle (1 ~ 30nm) synthesized in this way has a large specific surface area, and the formed nanostructure (10 ~ 300nm) has a high optical activity than the conventional commercial photocatalyst with a special high energy.

In this case, nanomaterials exhibit different properties from the bulk state, and if the chemical properties such as the size, composition, and shape of the material are controlled at a size of 100 nm or less, the physical properties such as optical properties, electrical properties, and magnetic properties of the materials can be freely changed. You can. Nanostructures formed using these nanomaterials have various characteristics. First, they have a very large surface because of their small size. Second, they can control physical properties chemically. Third, they have excellent target binding properties. It is a very stable substance. The extraordinary high energy of these nanostructures themselves and the unique action of the nanostructures can cause a variety of functions in all of you.

The shape of the nanostructures is shown in FIG. 1. 1 is an analysis of the face centered cubic (FCC) of the Pd element.

In the case of FIG. 1, the Pd is a pure Pd metal, and a scanning transmission electron microscopy (STEM) photograph showing the state in which the crystal structure is almost perfectly arranged. These Pd nanoparticles are re-integrated, which may be said to be due to molecular self-assembly, and even after they are integrated, they have an annular hollow shape. Even if this integration continues, it continues to show a ring shape to some extent, and has a tendency like a fractal. In the end, this means that Pd has high crystallization at the atomic level, and it is assumed that it has high reactivity and selectivity.

It is also believed that the high reactivity and selectivity as the catalyst for artificial photosynthesis and the high crystals at the atomic level cause high reactivity and selectivity.

In the present invention, "artificial photosynthesis" refers to a process of generating a hydrocarbon compound by combining with carbon dioxide after decomposition of water in a situation in which light such as visible light or ultraviolet light is irradiated using a catalyst.

The Pd nanostructure has a very high hydrogen adsorption force. In particular, the hydrogen adsorption force is referred to as "normal temperature and pressure in the laboratory" (hereinafter, "normal temperature and pressure", where "normal temperature and pressure" means the temperature and 1 atmosphere of water to maintain a liquid state Of course, it also appears to be very efficient, which is about 100 times larger than the volume. The reaction can be carried out even under 1 atm, and of course, even when the pressure exceeds this.

In addition, the Pd nanostructures act as a catalyst for decomposing water in the process of irradiating water with various light rays including visible light, ultraviolet light, and the like to produce hydrogen and oxygen. This is also commonly called photolysis of water.

The Pd nanostructure is manufactured as follows.

In the nanostructure manufacturing method of the present invention, Pd nanoparticles are 100% pure Pd nanoparticles, which are 1-30 nm cubic nanoparticles by electrolysis in an electrolyte using Pd rods, and Pd nanoparticles are produced by controlling hydrogen ion concentration. It is to mass produce a cyclic Pd structure having a size of 10 ~ 300nm, the shape of which is self-assembled, the shape of which is controlled in a ring shape.

At this time, the electrode and water are electrolyzed in the electrolyte using a Pd rod as an electrode.

Here, the electrolyte may be used in various ways, but the concentration is 0.01% to 5% based on sodium chloride (NaCl), and the current and voltage are alternately adjusted between 0.01A to 10A and 2V to 40V, so that the anode has chloride ion ( Cl ⁻ ) combines with palladium (Pd) to form metal salts of Pd and Cl.

This process is performed in the process of evenly stirring the generated Pd nanoparticles and the electrolyte.

Pd and Cl metal salts of palladium chloride (PdCl ₂ ) are formed by the palladium (Pd) atom, which is a cubic Pd nanoparticle of 1 to 30 nm, with the chloride ion (Cl ⁻ ) dropping by hydrogen ions (H ⁺ ) generated around the cathode. Is generated. The resulting palladium (Pd) atoms undergo molecular self-assembly (aggregation) to form Pd nanostructures and settle to the bottom of the production vessel. In the precipitated Pd, palladium chloride and Pd nanostructures are mixed. Here, the Pd nanostructure precipitated to the bottom or the Pd nanostructure gradually precipitated to the bottom is separated from the sodium chloride solution to obtain a pure Pd nanostructure. At this time, the chloride ion (Cl ⁻ ) is a chlorine gas (Cl ₂ ) to fly or re-enter the sodium chloride (NaCl) solution, the hydrogen ion (H ⁺ ) receives the electron becomes a hydrogen gas (H ₂ ). Here, the pH control of the solution is very important because the pH is related to the aggregation form of the Pd nanostructure. It can be seen that smooth aggregation usually occurs at pH 6-10. In this case, pH adjustment of the solution has a hydrogen ion (H ⁺⁾ and hydroxide ions (OH ^-) to adjust the voltage and current, the pH is adjusted as to control the amount of.

Another achievement of the present invention is that the method of obtaining the Pd nanostructures is again greatly improved.

When the Pd rod (pure Pd metal mass) used as an electrode in the process was occluded (absorbed and stored) before use as an electrode, the production efficiency of Pd nanostructures could be dramatically increased. Here, occlusion refers to the injection of hydrogen between the Pd lattice.

The method of occluding hydrogen in Pd metal is widely known, and any method may be used. One of the hydrogen occlusion methods is that hydrogen is occluded in Pd when the Pd metal is raised in pressure and temperature in a hydrogen gas atmosphere. At this time, the hydrogen storage amount is proportional to the pressure, temperature and time.

In addition, since the storage amount of hydrogen is important to continuously discharge hydrogen in water, it is necessary to occlude as much hydrogen as possible.

The subsequent process is similar to using Pd without occluding hydrogen, as follows.

Electrodes and water are electrolyzed in electrolyte using Pd absorbed hydrogen.

In this case, various electrolytes may be used, but the concentration is 0.01% to 5% based on sodium chloride (NaCl), and the current and voltage are alternately controlled between 0.01A to 10A and 2V to 40V to allow chloride ion ( Cl ⁻ ) combines with palladium (Pd) to form metal salts of Pd and Cl.

This process is performed in the process of evenly stirring the resulting nanoparticles and the electrolyte.

Pd and Cl metal salts of palladium chloride (PdCl ₂ ) are formed by the hydrogen ions (H ⁺ ) generated around the cathode, and the chloride ions (Cl ⁻ ) are dropped. However, most of the stored hydrogen is released and the chloride ions (Cl ⁻ ) the separation to produce a metal salt palladium chloride of Pd and Cl (PdCl ₂₎ is a chloride ion (Cl by the hydrogen ion (H ⁺⁾ generated by the surrounding ^anode-in cubic Pd nanoparticles of 1 ~ 30nm) the falling palladium (Pd) Atoms are generated. The resulting palladium (Pd) atoms undergo molecular self-assembly (aggregation) to form Pd nanostructures and settle to the bottom of the production vessel. In the precipitated Pd, palladium chloride and Pd nanostructures are mixed. Here, the Pd nanostructure precipitated to the bottom or the Pd nanostructure gradually precipitated to the bottom is separated from the sodium chloride solution to obtain a pure Pd nanostructure. At this time, the chloride ion (Cl ⁻ ) is a chlorine gas (Cl ₂ ) to fly or re-enter the sodium chloride (NaCl) solution, the hydrogen ion (H ⁺ ) receives the electron becomes a hydrogen gas (H ₂ ). Here, the pH control of the solution is very important because the pH is related to the aggregation form of the Pd nanostructure. It can be seen that smooth aggregation usually occurs at pH 6-10. In this case, pH adjustment of the solution has a hydrogen ion (H ⁺⁾ and hydroxide ions (OH ^-) to adjust the voltage and current, the pH is adjusted as to control the amount of.

Particularly, when Pd containing hydrogen is used, a large amount of Pd nanostructures can be produced over several hours. When Pd without hydrogen is used, production of Pd nanostructures can be inferior compared to stopping production within minutes. .

In addition, when using Pd rods that do not occlude hydrogen, palladium chloride and Pd nanostructures are mixed in the precipitated Pd. However, when Pd rods that occupy hydrogen are used, pure Pd nanostructures can be obtained. have.

Here, the hydrogen-containing Pd rod produces 100% purity Pd nanoparticles, which are 1-30 nm cubic nanoparticles in electrolysis, and the Pd nanoparticles produced are self-assembled by occluding hydrogen. It has a cyclic Pd structure having a size of 10 to 300 nm whose shape is cyclically controlled.

In addition, the process of fixing the Pd nanostructure to minimize the change in shape can be performed.

The cyclic Pd nanostructure is characterized in that the shape of the structure is fixed by treatment in an atmosphere from which oxygen is removed for 60 minutes to 120 minutes at a pressure of 10 to 100 atmospheres while maintaining the temperature 10 ℃ ~ 200 ℃.

At this time, after removing oxygen to prevent oxidation of Pd into PdO, argon and nitrogen, which are inert gases, are added, and the pressure is applied to fix the shape of the cyclic Pd nanostructure.

In other words, in order to fix the resulting nanostructures, the temperature is maintained at 10 ° C. to 200 ° C. and treated in an atmosphere from which oxygen is removed for 60 minutes to 120 minutes at a pressure of 10 to 100 atmospheres.

The treated Pd is mainly formed of a cyclic Pd nanostructure.

The cyclic Pd nanostructure was found to have an excellent effect as a photosensitivity catalyst.

The structure of this catalyst generally has a structure capable of amplifying more than about 1.23 eV of energy, which is the principle energy required to oxidize or reduce water, to sunlight in the visible range, and is actually higher than many studies obtained on single crystal surfaces. It can be seen that it is a catalyst having reactivity and selectivity.

The unique catalytic properties of the shape-controlled nanoparticles can control the optical properties by varying the distance between the nanoparticles, and show not only the large surface response of the nanoparticles, but also the quantum dot energy of the nanostructures. .

The general redox equation for water is

reduction ^{_{(reduction) 2H 2 O + 2e - ---}} > H 2 + 2OH -

oxidation _{(oxidation) 2H 2 O ---> O 2} + 4H + + 4e -

net 2H ₂ O ---> O ₂ + 2H ₂

.

In other words, the development of this technology means the invention of the core technology of the artifical photosystem that the world intends to do.

According to the present invention, it is possible to produce a Pd nanostructure that can amplify a large energy by a simple method, and demonstrated the excellent performance by performing a photolysis experiment of water with the nanostructures thus produced.

The present invention also provides a Pd nanostructure catalyst for water photolysis comprising the cyclic Pd nanostructure.

The present invention also provides a cyclic Pd nanostructure, characterized in that the cyclic Pd nanostructure is used as a Pd nanostructure catalyst for water photolysis in a water pollution emission suppression or prevention facility.

The water pollution emission suppression or prevention facilities include petroleum refining facilities, petrochemical products, manufacturing facilities, refineries, gas stations or laundry facilities.

Most of the catalysts used in the conventional water decomposition reaction can decompose water only in the ultraviolet region, but the cyclic Pd nanostructure catalyst of the present invention widens the range of light to visible light, so that it is several hundred times higher than conventional photocatalysts in general sunlight. It is a breakthrough catalyst that can photolyze water.

Since the solar energy is about 4-12 times higher than the photoreactor with 20,000 to 100,000 Lux, when the water is decomposed with the Pd nanostructure catalyst of the present invention, the production of hydrogen (H ₂ ) and oxygen (O ₂ ) is proportional to that. It can be seen that the increase.

In addition, the photodegradation of water using the cyclic Pd nanostructure of the present invention is to decompose water into ordinary sunlight without electrical energy or chemical action. The cyclic Pd nanostructure catalyst of the present invention acts as a catalyst when water decomposes to produce hydrogen (H ₂ ), dissociate into H ⁺ and e ⁻ , and then combine with carbon dioxide (CO ₂ ) to produce a hydrocarbonate. It is a groundbreaking catalyst that enables the complete treatment of carbon dioxide (CO ₂ ), which is the main culprit of global warming, and furthermore, the technology of recycling carbon dioxide (CO ₂ ). At this time, the carbon dioxide (CO ₂ ) reduction capacity was 50 ~ 50cc distilled water in a 200cc quartz (Quartz) Erlenmeyer flask at 80,000Lux sunlight, and 1g of cyclic Pd nanostructures were irradiated for 1 hour.

In addition, cyclic Pd nanostructures containing hydrogen (H ₂ ) generated by the application of water photolysis catalyst can be used to separate hydrogen at a constant temperature or pressure, and hydrocarbons can be combined with continuous hydrogen separation and carbon dioxide (CO ₂ ). Can produce 50cc of distilled water was added to 200cc quartz (Quartz) Erlenmeyer flask at 80,000 lux of general sunlight, and 1g of cyclic Pd nanostructure was irradiated for 1 hour to produce 50 ~ 60cc of hydrogen. This result is far superior to other existing hydrogen storage experiments.

The photolysis experiment of water is as follows.

The cyclic Pd nanostructure catalyst is supported on the photoreactor in distilled water and irradiated with light to perform water decomposition of the cyclic Pd nanostructure catalyst.

           ↓ light

H ₂ O → H ₂ + 1/2 O ₂

Here, hydrogen (H ₂₎ generated from the water and oxygen (O ₂₎ of hydrogen (H ₂₎ is absorbed in the nanostructure Pd catalyst and bubbles of oxygen (O ₂₎ generated from the catalyst surface and is formed with air bubbles.

At this time, the generation amount of oxygen (O ₂ ) can be measured by gas chromatography (GC), and the generation amount of hydrogen (H ₂ ) can also be measured by gas chromatography (GC).

Lzc-Vislamps are Lzc-VA lamps used for the photolysis experiment of water, which is a lamp for generating visible light, and an Lzc-uVA lamp is a lamp for generating ultraviolet light.

Lzc-Vislamps are 8760Lux with 49mW / cm ² and wavelength of 380 ~ 750nm.

Lzc-uVA lamps are 16300Lux with 83mW / cm ² and 300 ~ 400nm wavelength.

At this time, there is almost no temperature change in the photoreactor.

In addition, the cyclic Pd nanostructure analysis may be performed using a transmission electron microscope (TEM), a high-resolution transmission electron microscopy (HREM), and a scanning transmission electron microscope (STEM). Analyzed.

Figure 2 shows the results of TEM analysis of the metal powder specimen of the cyclic Pd nanostructures.

As shown in FIG. 2, the size of the cyclic Pd nanostructure to which the Pd nanoparticles are attached to form a ring is about 10 nm, and the A region (most regions) is almost composed of Pd elements.

3 shows the results of STEM analysis of the metal powder specimen of the cyclic Pd nanostructure.

3 shows that the Pd nanoparticles form a complete structure with a cyclic Pd nanostructure. That is, Figure 3 is a face centered cubic (FCC) analysis of the Pd nanoparticles, the Pd nanoparticles are pure Pd metal scanning electron microscope showing the state that the crystal structure is almost perfectly arranged (scanning transmission electron microscopy; STEM). Here, the ringing of the light shows that every single nanoparticle is exactly a crystal.

FIG. 4 is a high-resolution transmission electron microscopy (HREM) photograph of a metal powder specimen of a cyclic Pd nanostructure, showing analysis of a contrast image by a transmitted electron beam.

As shown in FIG. 4, the Pd nanostructure of the present invention is cyclic.

FIG. 5 is a Scanning Transmission Electron Microscopy (STEM) picture of the metal powder specimen of the cyclic Pd nanostructure, the left picture is BF, that is, the Z-contrast of STEM, and the right picture is HAADF, The picture shows the z-contrast of STEM.

As shown in FIG. 5, the Pd nanostructure of the present invention is cyclic.

Hereinafter, the present invention will be described in detail by way of examples.

However, the following examples are illustrative of the present invention, and the contents of the present invention are not limited by the following examples.

Example 1

The electrode and water were electrolyzed in 500 g of 3% sodium chloride electrolyte using 300 g of Pd rod as an electrode, thereby producing 100 g of 100% pure Pd nanoparticles, which are 1-30 nm cubic nanoparticles. At this time, the current and voltage is 0.01A ~ 10A, 2V ~ In adjusted to pH 8 by controlling alternately between 40V anode chloride ions (Cl ^-) palladium chloride and palladium Pd metal salts in combination with Cl (Pd) ( 280 g of PdCl ₂ ) were produced. The palladium chloride (PdCl ₂ ) is ions (Cl ⁻ ) drop by the hydrogen ions (H ⁺ ) generated around the cathode and a palladium (Pd) atom, a cubic Pd nanoparticle of 1 to 30nm was produced. The resulting palladium (Pd) atoms were molecularly assembled (aggregated) to form Pd nanostructures and settled to the bottom of the production vessel. The Pd nanostructures precipitated to the bottom or Pd nanostructures gradually settled to the bottom are separated from the sodium chloride solution to control the hydrogen ion concentration, and the Pd nanoparticles produced by self-assembly are uniformly shaped, that is, the shape is controlled. 50 g of a cyclic Pd structure having a size of 10 to 300 nm was produced.

Example 2

Photolysis of water was performed using the Pd nanostructure produced in Example 1. First, 50 cc of distilled water was put into a 200 cc quartz conical flask, and 0.1 g of a cyclic Pd nanostructure was added thereto.

Then, Lzc-uVA lamps; 83mW / cm ² (= 16300Lux); wavelength 300-400nm) or visible light lamps (Lzc-Vislamps; 49mW / cm ² (= 8760Lux); wavelength 380-750nm) A triangular flask containing the cyclic Pd nanostructure was placed in a photoreactor (Luzchem LZC-5) attached to each of the four sides.

Thereafter, the photoreactor was exposed to visible light or ultraviolet light for several ten minutes to several hours to measure the degree of photolysis of water, thereby obtaining Graph 1 or Graph 2 below.

Experimental Example 1

Analysis of photolysis experiment of water

Agilent GC-TCD 6890 (column C-9197-2) was used for oxygen analysis and hydrogen analysis of the photolysis experiment of water of Example 2.

Experiment result

Graph 1 (cyclic Pd nanostructure; visible light lamp)

50 cc of distilled water was added to a 200 cc quartz conical flask, and 0.1 g of cyclic Pd nanostructure was added thereto, and visible light was irradiated for 1 hour, resulting in 2.7 cc of oxygen.

Hydrogen was generated in 5.4cc and the generated hydrogen was absorbed by the cyclic Pd nanostructure.

Graph 2 (cyclic Pd nanostructure; UV lamp)

50 cc of distilled water was added to a 200 cc quartz conical flask, and 0.1 g of cyclic Pd nanostructure was added thereto.

Hydrogen was generated at 9.8 cc and hydrogen was absorbed by the cyclic Pd nanostructure.

Example 3

Photolysis of water was performed using the Pd nanostructure produced in Example 1. First, 50cc of distilled water was put into a 200cc quartz conical flask and 0.1g, 0.12g, 0.15g, and 0.2g of cyclic Pd nanostructures were put therein.

The cyclic Pd nanostructures were then placed in a photoreactor (Luzchem LZC-5) with four visible light lamps (Lzc-Vislamps; 49 mW / cm ² (= 8760 Lux); four wavelengths of 380 to 750 nm) attached to each side. The contained Erlenmeyer flask was added.

Thereafter, the photoreactor was exposed to visible light for several tens of minutes to several hours to measure the degree of photolysis of water, thereby obtaining Graph 3 below.

Experimental Example 2

Analysis of Photodegradation Test of Water According to Cyclic Pd Nanostructure Content

In the oxygen analysis and hydrogen analysis of the photolysis experiment of water of Example 3, the amount of water reduction was measured.

Experiment result

Graph 3 (cyclic Pd nanostructure; visible light lamp)

50cc of distilled water was added to a 200cc quartz conical flask and 0.1g of cyclic Pd nanostructure was added thereto, and the visible light was irradiated for 1 hour. The water was photocatalyzed in 3.5cc, and 0.12g of cyclic Pd nanostructure was added for 1 hour. After irradiating visible light, water was photocc decomposed 4.4cc, 0.15g of cyclic Pd nanostructure was added and visible light was irradiated with 5.4cc of light and 0.2g of cyclic Pd nanostructure was visible for 1 hour. The water was photolyzed 7.6cc.

As a result of the photolysis of water, the cyclic Pd nanostructure was able to decompose water into hydrogen and oxygen, and the generated hydrogen was occluded in the cyclic Pd nanostructure. From the naked eye, it can be seen that the volume of the hydrogen-containing cyclic Pd nanostructure increases significantly. Hydrogen and oxygen generation decreased in the order of ultraviolet light> visible light.

In addition, since the solar energy is about 4 to 12 times higher than that of the photoreactor with 20,000 to 100,000 Lux, the amount of oxygen and hydrogen is increased in proportion to the photolysis of water. 54 cc of hydrogen was generated as a result of experiment as in Example 2 in 80,000 Lux solar cells.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

1 is a scanning transmission electron microscopy (STEM) photograph of the cyclic Pd nanoparticle structure prepared by the present invention.

Figure 2 is a photograph showing the results of TEM analysis of the metal powder specimen of the cyclic Pd nanostructures.

Figure 3 is a photograph showing the results of STEM analysis showing a state in which the crystal structure of the metal powder specimen of the cyclic Pd nanostructure is almost perfectly arranged.

FIG. 4 is a high-resolution transmission electron microscopy (HREM) photograph of a metal powder specimen of a cyclic Pd nanostructure, showing analysis of a contrast image by a transmitted electron beam.

FIG. 5 is a Scanning Transmission Electron Microscopy (STEM) picture of the metal powder specimen of the cyclic Pd nanostructure, the left picture is BF, that is, the Z-contrast of STEM, and the right picture is HAADF, The picture shows the z-contrast of STEM.

Claims (5)

A cyclic Pd nanostructure formed by agglomerating cubic Pd nanoparticles by self-assembly by adjusting the pH in a range of 6 to 10. The cyclic Pd nanostructure of claim 1, wherein the cubic Pd nanoparticles are shape-controlled to have a particle diameter of 1 to 30 nm. The method of claim 1, wherein the cyclic Pd nano structure is characterized in that the shape of the structure is fixed by treating in an atmosphere from which oxygen is removed for 60 minutes to 120 minutes at a pressure of 10 to 100 atm while maintaining the temperature 10 ℃ ~ 200 ℃ Cyclic Pd nanostructures. The cyclic Pd nanostructure according to any one of claims 1 to 3, wherein the cyclic Pd nanostructure is used as a Pd nanostructure catalyst for water photolysis in a water pollution emission suppression or prevention facility. A Pd nanostructure catalyst for water photolysis, comprising the cyclic Pd nanostructure according to any one of claims 1 to 3.

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