Method for producing nanoparticle catalyst and electrochemical catalyst produced thereby

Abstract

The present invention relates to a method for producing a nanoparticle catalyst and an electrochemical catalyst produced thereby and, more specifically, to a method for producing a nanoparticle catalyst and an electrochemical catalyst produced thereby, wherein an inorganic oxide precursor and a catalyst precursor are simultaneously synthesized in a single reactor by using water (H2O)) in order to produce a nanoparticle catalyst in which a noble metal is dispersed and supported in the form of atomic clusters on an inorganic oxide as a support, so that efficiency improvement and an increase in dispersion of the catalyst supported on the support can be achieved due to a single producing process, and the catalyst can be used as an electrochemical catalyst, such as a catalyst for generating hypochlorous acid or oxygen through water electrolysis.

Description

Method for manufacturing nanoparticle catalyst and electrochemical catalyst produced thereby

[0001] The present invention relates to a method for producing a nanoparticle catalyst and an electrochemical catalyst therefor, and more particularly, to a method for producing a nanoparticle catalyst in which a noble metal is dispersed and supported in the form of atomic clusters on an inorganic oxide as a support, by simultaneously synthesizing an inorganic oxide precursor and a noble metal catalyst precursor in a single reactor using water (H2O), thereby improving efficiency according to a single production process and increasing the degree of dispersion of the catalyst supported on the support, and which can be used as an electrochemical catalyst, such as a catalyst for producing hypochlorous acid or oxygen through water electrolysis, and an electrochemical catalyst therefor.

[0002]

[0003] Conventional hypochlorous acid and oxygen generation catalysts through electrolysis require overvoltage for slow oxygen generation reactions, and for high stability and activity, precious metal-based catalysts such as Ir and Ru are essential to be used with high loading (>30 wt.%). However, when the amount of precious metal is increased for high loading, it is difficult to uniformly control the particle size of the precious metal, and there is a disadvantage that the catalytic efficiency decreases due to particle size growth.

[0004] In the past, precious metals were synthesized by dispersing them on a support using an impregnation method, but since a pre-synthesized support had to be added to a catalyst precursor solution and then impregnated using a reducing agent, the process had the disadvantage of being complicated.

[0005] In addition, in the case of TiO2 particles, which are widely used as a support, the production of TiO2 raw material powder particles using conventional metal alkoxides and water has been difficult due to the high cost of the starting materials and the rapid hydrolysis reaction caused by the sensitive reaction with moisture in the air.

[0006]

[0007] In order to solve the above problems, the present invention aims to provide a method for manufacturing a nanoparticle catalyst and an electrochemical catalyst resulting therefrom, which can improve efficiency and increase the dispersion of a catalyst supported on a support by simultaneously synthesizing an inorganic oxide precursor as a support and a noble metal catalyst precursor using water (H2O) in a single reactor, and which can be used as an electrochemical catalyst such as a catalyst for producing hypochlorous acid and oxygen through water electrolysis.

[0008]

[0009] To this end, the present invention relates to a method for manufacturing a nanoparticle catalyst,

[0010] A method for producing a nanoparticle catalyst, comprising: a step of introducing a mixture of an inorganic oxide precursor and a noble metal catalyst precursor into an alcohol solvent in a single reactor; a step of adding water as an oxidizing agent to the reactor to precipitate inorganic oxide particles by a hydrolysis reaction of the inorganic oxide precursor, and a step of forming an atomic cluster catalyst hydrate in which the noble metal catalyst precursor is supported on the inorganic oxide particles in a hydrated form; and a step of calcining the atomic cluster catalyst hydrate to produce a nanoparticle catalyst in which the noble metal atomic cluster catalyst particles are supported on the inorganic oxide particles.

[0011] The above inorganic oxide precursor may be selected from the group consisting of titanium(III) chloride, titanium(IV) isopropoxide and titanium(IV) butoxide, and may also include aluminum and zirconium precursors having a similar chemical composition.

[0012] The inorganic oxide particles of the above nanoparticle catalyst may be TiO2, Al2O3, ZrO2, and preferably TiO2.

[0013] The above noble metal catalyst precursor may be selected from the group consisting of iridium chloride, iridium chloride, iridium acetate, iridium nitrate, and hydrates thereof, or may be selected from the group consisting of ruthenic acid, ruthenium chloride, ruthenium acetate, ruthenium nitrate, and hydrates thereof.

[0014] The atomic cluster catalyst particles supported on the above nanoparticle catalyst may be selected from the group consisting of iridium (Ir), ruthenium (Ru), oxides thereof, and mixtures thereof.

[0015] The inorganic oxide particles of the above nanoparticle catalyst may be 10 to 1,000 nm,

[0016] The atomic cluster catalyst particles supported on the above nanoparticle catalyst may exist in the form of clusters having a size of 0.2 to 5 nm.

[0017] The above alcohol solvent may be n-butanol or ethanol.

[0018] The calcination temperature of the above atomic cluster catalyst hydrate may be 250 to 650°C.

[0019] In another invention, an electrochemical catalyst manufactured by the above method is characterized in that noble metal atom cluster catalyst particles are supported on inorganic oxide particles in the form of atomic clusters having a size of 0.2 to 5 nm, the noble metal atom cluster catalyst particles are selected from the group consisting of iridium (Ir), ruthenium (Ru), oxides thereof, and mixtures thereof, and the inorganic particles are TiO2 having a size of 10 to 1,000 nm.

[0020] Another invention relates to a hypochlorous acid water generating electrode, a catalyst electrode for water electrolysis oxygen generation, or a membrane-electrode assembly for water electrolysis oxygen generation, comprising the electrochemical catalyst.

[0021]

[0022] According to the present invention, the present invention has a structure in which catalyst particles in the form of atomic clusters having a size of 0.2 to 5 nm are uniformly supported on an inorganic oxide as a support, and unlike conventional manufacturing methods, it has the advantage of being able to manufacture a nanoparticle catalyst in which noble metal atomic cluster catalyst particles are highly dispersed on an inorganic oxide support through a heat treatment process after a single-step one-pot reaction, using only water without using an oxidizing agent or reducing agent.

[0023] This is because, in the conventional case where a catalyst, a precious metal oxide, is dispersed and supported on an inorganic oxide by adding a particle-shaped support, the particles are dispersed on the surface of the support, so that the higher the content of the precious metal oxide, the more difficult it is to control the size of the catalyst particles. In addition, the dispersion of the catalyst is affected depending on the surface state and functional groups of the support, so that the stability and catalytic activity of the catalyst are reduced. However, according to the present invention, a highly dispersed catalyst can be synthesized through simultaneous synthesis, so that even under tap water conditions with a very low concentration of chloride ions, it can have high hypochlorous acid production efficiency and high durability through electrolysis, and can be used as a catalyst that can efficiently react in an oxygen production reaction through electrolysis under acidic conditions.

[0024]

[0025] Figure 1 is a conceptual diagram briefly schematically illustrating the manufacturing process of the present invention.

[0026] Figure 2 is a SEM image of TiO2 manufactured according to a manufacturing example of the present invention.

[0027] Figure 3(a) is a SEM image of IrO2 / TiO2 manufactured according to an embodiment of the present invention.

[0028] Figure 3(b) is a SEM image of a nanoparticle catalyst manufactured according to an embodiment of the present invention.

[0029] Figure 3(c) is a diffraction pattern image of a nanoparticle catalyst manufactured according to an embodiment of the present invention.

[0030] FIG. 4 is a TEM and STEM HADDF image of an atomic cluster catalyst formed after heat treatment and sintering according to an embodiment of the present invention.

[0031] Figure 5 is an image of the XRD analysis results of an atomic cluster catalyst formed after heat treatment and sintering according to an embodiment of the present invention.

[0032] Figure 6 is a graph showing the results of oxygen generation electrochemical evaluation of examples and comparative examples of the present invention.

[0033]

[0034] Hereinafter, the present invention will be described in detail with reference to the drawings.

[0035] Figure 1 is a conceptual diagram schematically illustrating the manufacturing process of the present invention, in which a mixture of an inorganic oxide precursor and a catalyst precursor is introduced into an organic solution, preferably an alcohol solvent, in a single reactor.

[0036] Thereafter, water as an oxidizing agent is added to the reactor to precipitate inorganic oxide particles through a hydrolysis reaction of the inorganic oxide precursor, and an atomic cluster catalyst hydrate in which the precious metal catalyst precursor is supported in a hydrated form on the inorganic oxide particles is formed. Unlike conventional manufacturing methods, this method is more environmentally friendly because it uses only water without using an oxidizing agent or reducing agent, and has an economic advantage because a separate washing process to remove compounds such as oxidizing agents and reducing agents after use can be omitted.

[0037] Afterwards, the catalyst is washed with deionized water to remove the organic solvent, dried, and then the formed atomic cluster catalyst hydrate is calcined to produce a nanoparticle catalyst in which noble metal atomic cluster catalyst particles are supported on the inorganic oxide particles.

[0038] The above calcination temperature can be 250 to 650°C, and the particle size of the catalyst can be controlled depending on the calcination temperature, and in particular, when the support is TiO2, the Anatase or Rutile crystal phase can be controlled.

[0039] The above inorganic oxide precursor may be selected from the group consisting of titanium(III) chloride, titanium(IV) isopropoxide, and titanium(IV) butoxide, and may also include aluminum and zirconium precursors having a similar chemical composition, and the inorganic oxide particles formed therefrom may be TiO2, Al2O3, ZrO2, and preferably TiO2. At this time, the size of the inorganic oxide particles may be 10 to 1,000 nm.

[0040] The atomic cluster catalyst particles supported on the above nanoparticle catalyst may be selected from the group consisting of iridium (Ir), ruthenium (Ru), oxides thereof, and mixtures thereof, and for this purpose, the noble metal catalyst may be selected from the group consisting of iridium chloride, iridium chloride, iridium acetate, iridium nitrate, ruthenic acid chloride, ruthenium chloride, ruthenium acetate, ruthenium nitrate, and hydrates thereof, and may be selected from the group consisting of mixtures thereof.

[0041] The atomic cluster catalyst particles supported on the above nanoparticle catalyst are in the form of clusters with a size of 0.2 to 5 nm. (See Fig. 3(b))

[0042] For reference, in the case of conventionally dispersing and supporting a precious metal oxide as a catalyst in an inorganic oxide by adding a particle-shaped support, the particles are dispersed on the surface of the support, so the higher the content of the precious metal oxide is dispersed, the more difficult it is to control the size of the catalyst particles. In addition, there is a limit to the degree of dispersion of the catalyst depending on the surface condition and functional groups of the support, but according to the present invention, it is possible to synthesize a catalyst in the form of a highly dispersed atomic cluster through simultaneous synthesis.

[0043] Hereinafter, a method for manufacturing an IrO2 / TiO2 nanoparticle catalyst according to one embodiment of the present invention will be described in detail.

[0044] First, Ti was prepared by adding ice water and H2O2 to the TiCl3 precursor solution, which is a support precursor. 4+ It can be manufactured by adding titanium peroxo complex until it forms an oxide and becomes transparent yellow. Any one of titanium chloride (Titanium(III) chloride), titanium isopropoxide (Titanium(IV) isopropoxide), and titanium butoxide can be used as a titanium precursor.

[0045] The precious metal precursor as a catalyst may include either iridium chloride (Iridium(III) chloride) or iridium(IV) chloride, and each precursor may be dissolved in an organic solvent such as butanol (n-butanol) or ethanol and mixed to a concentration of 0.1 M to 0.2 M for use.

[0046] Here, the above mixed precursor ratio may be 1:9 to 9:1 depending on the IrO2:TiO2 composition ratio.

[0047] Depending on the pH control of the above solution, the phase of TiO2 can be controlled to anatase, rutile, and brookite, and rutile can be formed when the pH is in the range of 0 to 2. (See Fig. 2)

[0048] Afterwards, water, which is an oxidizing agent, is added to precipitate amorphous TiO2 through a hydrolysis reaction. Finally, an annealing process in the range of 250 to 650°C is performed to crystallize TiO2 and form IrO2, thereby producing a catalyst in the form of IrO2 supported on TiO2. The final manufactured TiO2 forms nanoparticles with a size of 10-1000 nm, and the catalyst IrO2 atomic cluster particles form nanoparticles with a size of 0.2-5 nm or less.

[0049]

[0050] The electrochemical catalyst according to the present invention manufactured by the above manufacturing method is characterized in that the catalyst particles are supported on inorganic oxide particles in the form of atomic clusters having a size of 0.2 to 5 nm, the catalyst particles are selected from the group consisting of iridium (Ir), ruthenium (Ru), oxides thereof, and mixtures thereof, and the inorganic particles are TiO2 having a size of 10 to 1,000 nm.

[0051] The above electrochemical catalyst can be included and used in a hypochlorous acid water generating electrode, a catalyst electrode for water electrolysis oxygen generating, or a membrane-electrode assembly for water electrolysis oxygen generating.

[0052] Preferably, in the case of the hypochlorous acid generating electrode according to the present invention, the electrolyte is Cl - It is a solution containing ions, Cl - The concentration of ions is preferably 1 mM to 600 mM or less.

[0053] In addition, when used in a catalyst electrode for producing oxygen by electrolysis according to the present invention, <pH 3인 전해질 용액인 것이 바람직하다.

[0054]

[0055] [Example]

[0056] 1. IrO2 / TiO2 catalyst manufacturing

[0057] Iridium trichloride, an iridium precursor, was dissolved in butanol to prepare a 0.2 M solution. Titanium trichloride, a titanium precursor, was dissolved in butanol, and hydrogen peroxide was added until the solution became transparent yellow to prepare a 0.2 M solution. 9.1 ml of the prepared 0.2 M iridium precursor and 28.2 ml of the 0.2 M titanium precursor were mixed, and 7.08 ml of butanol was added and stirred. 4 ml of deionized water was added to the mixture while stirring, and the mixture was reacted overnight at room temperature. Afterwards, the mixture was heated and dried at 90 degrees while stirring, and then the residual solvent was removed by drying at 90 degrees in a box oven. Finally, the formed product was calcined at 350 degrees in air in a box oven for 1 hour.

[0058] As a result, as shown in the TEM image of Fig. 3, it was confirmed that TiO2 was formed as a support simply by adding deionized water.

[0059] In addition, as shown in Fig. 4, it was confirmed that IrO2 with a size of 0.2 nm to 2 nm was evenly dispersed on TiO2 after sintering by heat treatment at 350 degrees. In addition, it was confirmed through XRD analysis in Fig. 5 that the final TiO2 crystal phase was synthesized in a mixed state of Rutile and Anatase.

[0060]

[0061] 2. Production of TiO2 using conventional methods

[0062] Titanium trichloride was dissolved in butanol solvent and prepared to 0.2 M by adding hydrogen peroxide until it became transparent yellow. 28.2 ml of 0.2 M titanium precursor was mixed, and 7.08 ml of butanol solvent was added and stirred. 4 ml of deionized water was added to the mixture solution while stirring and the mixture was reacted at room temperature. Afterwards, the mixture solution was heated and dried at 90 degrees while stirring and the residual solvent was removed by drying at 90 degrees in a box oven. Finally, the formed product was calcined in air at 340 degrees in a box oven for 1 hour. As a result, rutile phase TiO2 as shown in Fig. 2 was synthesized.

[0063]

[0064] 3. Oxygen generation evaluation

[0065] Table 1 and Fig. 6 below are graphs showing the results of evaluating oxygen evolution using a linear sweep voltammogram in a 0.1 M HClO4 electrolyte using the IrO2 / TiO2 catalyst manufactured above and, as a comparative example, a commercial catalyst, Elyst Ir75 0480 (Umicore). Through this, it was confirmed that the catalyst manufactured according to the present invention exhibited a high oxygen evolution current density at a lower overvoltage.

[0066] Parameter implementation Preliminary comparison Budget Oxygen generation onset voltage [V] 1.41 1.48 1.8 V (vs RHE) Current density (A / g) 550 4160 5

[0067] Although the present invention has been described with examples, this is only one example among various embodiments including the gist of the present invention, and the purpose is to enable a person of ordinary skill in the art to easily practice it, and it is clear that the present invention is not limited to the above-described examples. Therefore, the protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope by modification, substitution, replacement, etc. within the scope that does not depart from the gist of the present invention will be included in the scope of the rights of the present invention.

Claims

1. A step of introducing a mixture of an inorganic oxide precursor and a precious metal catalyst precursor into an alcohol solvent in a single reactor; A step of adding water as an oxidizing agent to the reactor to precipitate inorganic oxide particles through a hydrolysis reaction of the inorganic oxide precursor, and forming an atomic cluster catalyst hydrate in which the noble metal catalyst precursor is supported in a hydrated form on the inorganic oxide particles; and A method for producing a nanoparticle catalyst, comprising: a step of calcining the above-mentioned atomic cluster catalyst hydrate to produce a nanoparticle catalyst in which noble metal atomic cluster catalyst particles are supported on the above-mentioned inorganic oxide particles; 2. In paragraph 1, A method for producing a nanoparticle catalyst, wherein the inorganic oxide precursor is at least one selected from the group consisting of titanium(III) chloride, titanium(IV) isopropoxide, and titanium(IV) butoxide.

3. In paragraph 1, A method for manufacturing a nanoparticle catalyst, wherein the inorganic oxide particles of the above nanoparticle catalyst are TiO2.

4. In paragraph 1, A method for producing a nanoparticle catalyst, wherein the inorganic oxide particles of the above nanoparticle catalyst have a size of 10 to 1,000 nm.

5. In paragraph 1, A method for producing a nanoparticle catalyst, wherein the above noble metal catalyst precursor is at least one selected from the group consisting of iridium chloride (IrCl3), ruthenium chloride (RuCl3), and mixtures thereof.

6. In paragraph 1, A method for producing a nanoparticle catalyst, wherein the above noble metal atom cluster catalyst particle is selected from the group consisting of iridium (Ir), ruthenium (Ru), oxides thereof, and mixtures thereof.

7. In paragraph 1, A method for manufacturing a nanoparticle catalyst, wherein the above noble metal atomic cluster catalyst particles exist in the form of clusters having a size of 0.2 to 5 nm.

8. In paragraph 1, A method for producing a nanoparticle catalyst, wherein the alcohol solvent is n-butanol or ethanol.

9. In paragraph 1, A method for producing a nanoparticle catalyst, wherein the calcination temperature of the above atomic cluster catalyst hydrate is 250 to 650°C.

10. The noble metal atomic cluster catalyst particles manufactured according to paragraph 1 are supported on inorganic oxide particles in the form of atomic clusters having a size of 0.2 to 5 nm, The above noble metal atom cluster catalyst particle is selected from the group consisting of iridium (Ir), ruthenium (Ru), oxides thereof, and mixtures thereof, The above inorganic particles are TiO2 having a size of 10 to 1,000 nm, and are an electrochemical catalyst.

11. A hypochlorous acid generating electrode comprising an electrochemical catalyst according to Article 10.

12. A catalyst electrode for producing oxygen by electrolysis of water, comprising an electrochemical catalyst according to Article 10.

13. A membrane-electrode assembly for producing oxygen by electrolysis of water, comprising an electrochemical catalyst according to Article 10.

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