KR100892099B1 - Method of preparing electrocatalysts for fuel cells and electrocatalysts thereof - Google Patents

Abstract

A method of manufacturing electrocatalysts for fuel cells, and the electrocatalysts manufactured thereby are provided to prevent separation of catalyst and a supporter generated in an electrode and to improve performance of the lectrocatalysts. A method of manufacturing electrocatalysts for fuel cells comprises the following steps of: synthesizing a spherical polymer(S11); adding the synthesizing polymer in a mixed solution(S12); forming a spherical titanium dioxide support by mixing a Ti(SO4)2 solution in a polymer-added mixed solution(S13); and forming the electrocatalysts by dipping a platinum catalyst in titanium dioxide supporter(S14).

Description

Method for preparing electrode catalyst for fuel cell and electrode catalyst produced by the same {Method of preparing electrocatalysts for fuel cells and electrocatalysts

The present invention relates to a method for producing an electrode catalyst for a fuel cell, and an electrode catalyst prepared thereby. In particular, an electrode catalyst carrying a platinum catalyst is formed on a titanium dioxide support having a hole, thereby reducing the amount of platinum used and the electrode catalyst. The present invention relates to a method for producing an electrode catalyst for a fuel cell, and an electrode catalyst produced thereby.

A fuel cell is a power generator that directly converts chemical energy of a fuel into electrical energy by an electrochemical reaction. Therefore, since it does not receive the thermodynamic limitations (Carnot efficiency) of the heat engine, the power generation efficiency is higher than that of the existing power generation apparatus, and there are almost no environmental problems with no pollution and noise, and it can be manufactured in various capacities. In addition, the fuel cell is a state-of-the-art technology with high expectations in terms of operation of the power system, such as easily installed in the power demand site to reduce the transmission and transmission facilities.

Fuel cells include Phosphoric Acid Fuel Cell (PAFC), Alkaline Fuel Cell (AFC), Molten Carbonate Fuel Cell (MCFC), Solid Oxide Fuel Cell (Solid Oxide) Fuel Cell, SOFC), and Polymer Electrolyte Membrane Fuel Cell (PEMFC). Among the fuel cells, a polymer electrolyte fuel cell (PEMFC) is a direct ion fuel cell using a hydrogen ion fuel cell (Photon Exchange Membrane Fuel Cell, PEMFC) and a liquid methanol directly. It can be subdivided into fuel cells (Direct Methanol Fuel Cell, DMFC).

In the technology for the ion exchange membrane fuel cell (PEMFC), the electrode catalyst having a very small particle is supported on the conductive carbon, impregnated with a liquid Nafion (perfluorinated membrane) polymer electrolyte, and then dried to dry the Nafion membrane. (nafion membrane) is formed.

An example of a technology for the ion exchange membrane fuel cell (PEMFC) is disclosed in the following document 1 (electrolysis electrode and its manufacturing method).

In the preparation method according to the following document 1, a pre-treatment step of washing and drying a conductive matrix made of titanium with a boiling oxalic acid solution, and dissolving one or two chlorides of noble metals composed of Ru, Sn, Ir, Pt and Pb in a hydrochloric acid solvent Next, the method includes preparing a patch solution by mixing in a dispersion solvent, and supporting the pretreated conductive matrix in the coating solution, followed by drying, followed by sintering in a heating furnace of 300 ° C. or higher. The matrix has a structure in which one or two kinds of chlorides of noble metals composed of Ru, Sn, Ir, Pt, and Pb are coated.

On the other hand, an example of a technique related to an electrode catalyst using silica or aluminum instead of using titanium is disclosed in Document 2 (a method for producing a fuel cell catalyst and a fuel cell catalyst).

The method for preparing a catalyst for a fuel cell and the catalyst for a fuel cell disclosed in Document 2 below produce a catalyst for a fuel cell by carrying a catalyst metal on a nano-frame, and the catalyst metal is regularly and polydispersed to nanoparticle size, thereby making it expensive. It provides a manufacturing method that can improve the price competitiveness by reducing the amount of metal used. In addition, the catalyst disclosed in Document 2 improves the efficiency and performance of the fuel cell due to the electrochemical characteristics of the oxidation-reduction active current density is very high.

[Document 1] Korean Unexamined Patent Publication No. 1998-0009525 (published Apr. 30, 1998)

[Document 2] Republic of Korea Patent Publication No. 10-0489215 (2005.05.17 announcement)

However, in the technique using the electrode catalyst having the Nafion membrane formed there is a problem that the Nafion membrane prevents the micropores of the porous catalyst, the support and the catalyst is separated to reduce the performance of the electrode catalyst.

In addition, in the technique disclosed in Document 1, there is a problem that the process is complicated by performing sintering several times at a relatively low temperature.

In addition, in the technique disclosed in Document 2, there is a problem that the surface area of the carbon spherical support is narrow, which lowers the efficiency of the electrode catalyst.

Accordingly, an object of the present invention is to solve the problems described above, and by replacing carbon as a support with spherical conductive titanium having holes, separation of the support and the catalyst generated in the electrode during long time operation Disclosed is a method of manufacturing an electrode catalyst for a fuel cell that can be prevented, and an electrode catalyst produced thereby.

Another object of the present invention is to reduce the production process of the electrode catalyst by sintering at a relatively high temperature, to reduce the amount of platinum used, and to manufacture a method for producing a fuel cell electrode catalyst for improving the performance of the electrode catalyst and To provide an electrocatalyst.

In order to achieve the above object, a first feature of the present invention is a method for producing an electrode catalyst for a fuel cell, comprising: synthesizing a spherical polymer, adding the polymer to a mixed solution, and a mixed solution to which the polymer is added. Mixing a Ti (SO ₄ ) ₂ solution to form a titanium dioxide support having a hole and supporting a platinum catalyst on the titanium dioxide support to form an electrode catalyst; It is to include.

According to a second aspect of the present invention, the step of synthesizing the spherical polymer comprises the steps of stirring a solution in which potassium persulfate is added to distilled water and styrene and styrene in the solution. It includes the step of reacting by adding methacrylic acid (methacrylic acid).

According to a third aspect of the present invention, in the second aspect, the step of reacting by adding styrene and methacrylic acid to the solution is carried out in a nitrogen atmosphere.

In a fourth aspect of the present invention, in the first aspect, in the step of adding the polymer to the mixed solution, the mixed solution is formed by adding distilled water, hydrochloric acid, and cetytrimethylammonium chloride.

In a fifth aspect of the present invention, the Ti (SO ₄ ) ₂ solution is added dropwise to the mixed solution to form a titanium dioxide support having a hole. And forming a mixed solution in which the (SO ₄ ) ₂ solution is dropped into a solid sample and calcining the solid sample.

A sixth aspect of the present invention is the fifth aspect, wherein the firing of the solid sample is performed in a temperature range of 600 ° C to 800 ° C.

According to a seventh aspect of the present invention, in the first aspect, the electrode catalyst formed in the step of forming an electrode catalyst by supporting a platinum (Pt) catalyst on the titanium dioxide support has a weight ratio of 20 wt% to 60 wt% of platinum. It is

In order to achieve the above object, an eighth feature of the present invention is a titanium dioxide (TiO ₂ ) support having a spherical polymer and titanium dioxide (TiO ₂ ) formed on the spherical polymer in an electrode catalyst for a fuel cell. It includes a platinum (Pt) catalyst supported on a titanium dioxide (TiO ₂ ) support.

A ninth feature of the present invention is the eighth feature, wherein the spherical polymer is formed by reacting potassium persulfate, styrene, and methacrylic acid.

A tenth feature of the present invention is the eighth feature, wherein the weight ratio of the platinum (Pt) catalyst supported on the titanium dioxide (TiO ₂ ) support is 20wt% to 60wt%.

As described above, according to the method for producing an electrode catalyst for a fuel cell according to the present invention and the electrode catalyst prepared thereby, the effect of preventing separation of the support and the catalyst generated in the electrode is obtained.

In addition, according to the method for manufacturing an electrode catalyst for a fuel cell according to the present invention and the electrode catalyst prepared thereby, the manufacturing process of the electrode catalyst can be reduced by sintering at a relatively high temperature, and the amount of platinum used can be reduced. The effect of improving performance is also obtained.

Briefly describing the present invention, the present invention forms an electrode catalyst by supporting a platinum catalyst on a titanium oxide support having holes.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

1 is a flowchart illustrating a method of manufacturing an electrode catalyst for a fuel cell according to the present invention.

As shown in FIG. 1, first, a spherical polymer is synthesized to manufacture an electrode catalyst for a fuel cell according to an embodiment of the present invention (S11). The synthesized polymer is added to a mixed solution of distilled water, hydrochloric acid and cetytrimethylammonium chloride (S12).

Next, a Ti (SO ₄ ) ₂ solution is mixed with the mixed solution to which the polymer is added to form a titanium dioxide (TiO ₂ ) support having holes (S13), and the titanium dioxide (TiO ₂ ) support The platinum catalyst is supported to form an electrode catalyst (S14).

Hereinafter, a method of manufacturing an electrode catalyst for a fuel cell according to an embodiment of the present invention will be described in more detail.

< Production Example  1> Manufacture of spherical polymer

A spherical polymer was first synthesized in order to prepare an electrode catalyst in which a platinum (Pt) catalyst was supported on a hollow spherical titanium dioxide (TiO ₂ ). The spherical polymer is stirred at 300 rpm (revolutions per minute) while maintaining a solution of 0.2 g of potassium persulfate added to 160 ml of distilled water at a temperature of 80 ° C. 54 ml of styrene and 2 ml of methacrylic acid were added to the solution to react for 24 hours in a nitrogen atmosphere.

< Production Example  2> hollow sphere TiO ₂  Catalyst manufacturing

As a precursor of titanium dioxide (TiO ₂ ), a Ti (SO ₄ ) ₂ solution was used. The impregnation method adds 0.07 g of a spherical polymer to a mixed solution of 32 ml of distilled water, 0.8 ml of hydrochloric acid, and 1.98 ml of cetytrimethylammonium chloride, and disperses with ultrasound for about 30 minutes, followed by Ti (SO ₄ ) 0.18 ml of ₂ solution was added dropwise to the solution.

The mixed solution in which the Ti (SO ₄ ) ₂ solution was added dropwise was aged at a temperature of about 70 ° C. for 12 hours, cooled to room temperature, and centrifuged to obtain a solid sample. And, by firing the solid sample in the temperature range of 600 ℃ to 800 ℃ (1 ℃ / min) for about 4 hours, a hollow titanium dioxide (TiO ₂ ) support is prepared.

An electrode catalyst was prepared by supporting a platinum (Pt) catalyst having a weight ratio of 20 wt% to 60 wt% on a hollow spherical titanium dioxide (TiO ₂ ) support prepared above. In this case, the white electrode Pt was formed using the H ₂ PtCl ₆ solution as a precursor.

< Experimental Example  1> hollow sphere TiO ₂  Assay of Support

In order to analyze the external appearance of the electrode catalyst prepared in Preparation Example 2 was carried out using a SEM.

2a and 2b are graphs showing the structure of the titanium dioxide support according to the present invention by firing at a temperature of 600 ℃ and 800 ℃, respectively.

As shown in FIG. 2A and FIG. 2B, the titanium dioxide (TiO ₂ ) support formed in <Production Example 2> has a certain shape, and it can be seen that holes are formed. Therefore, the electrode catalyst supporting the platinum catalyst on the titanium dioxide support has a proton movement in the electrode, and the blockage of holes by a binder such as Nafion is reduced, so that the reaction frequency of the catalyst can be improved. will be. In addition, the amount of platinum Pt used can be reduced.

< Experimental Example  2> hollow sphere Pt Of TiO ₂  Performance Comparison of Electrocatalysts

Data on current-voltage for evaluating the performance of the electrode catalyst in which the platinum (Pt) catalyst was loaded on the hollow spherical titanium dioxide (TiO ₂ ) prepared in Example 2 were measured.

3 is a graph comparing current-voltage performance of electrode catalysts having different weight ratios of platinum loading according to the present invention.

As shown in FIG. 3, each of the data of the reference numeral 31, the reference numeral 32, and the reference numeral 33 is a result of evaluating the performance of the electrode catalyst by changing the weight ratio of platinum (Pt) / titanium dioxide (TiO ₂ ). . Data of reference number 31 is the weight ratio of platinum (Pt) / titanium dioxide (TiO ₂ ) is 20wt% / 80wt%, data of reference number 32 is the weight ratio of platinum (Pt) / titanium dioxide (TiO ₂ ) is 40wt % / 60wt%, the data of reference number 33 shows that the weight ratio of platinum (Pt) / titanium dioxide (TiO ₂ ) 60wt% / 40wt% to be. 60 wt% / 40 wt% of an electrode catalyst having a weight ratio of platinum (Pt) / titanium dioxide (TiO ₂ ) of 20wt% / 80wt% It was found that the current density (peak density cm ^-2 ) was about 1.5 times higher at the peak than the phosphorous electrode catalyst.

4 is a graph showing the current generation duration of the electrode catalyst according to the present invention.

As shown in FIG. 4, the change in current density over time of the electrode catalyst having a weight ratio of platinum (Pt) / titanium dioxide (TiO ₂ ) of 60 wt% / 40 wt% was observed. Although the current density was unstable for the first 20 minutes, it was observed to maintain a stable state over time. As a result, by using a spherical titanium dioxide support having holes, the use of platinum can be reduced, and protons can be continuously generated without separating the catalyst in the electrode for a long time.

As mentioned above, although the invention made by this inventor was demonstrated concretely according to the said Example, this invention is not limited to the said Example and can be variously changed in the range which does not deviate from the summary.

The present invention provides a method for producing an electrocatalyst for a fuel cell, and a technique related to the electrocatalyst produced thereby. Its application fields include those that can be used in the power system, such as fuel cells that can reduce environmental problems with no pollution and noise, and can be installed in various capacity. Can be.

1 is a flow chart illustrating a method for manufacturing an electrode catalyst for a fuel cell according to the present invention.

Figure 2a is a photograph showing the structure of the titanium dioxide support according to the invention by firing at a temperature of 600 ℃.

Figure 2b is a photograph showing the structure of the titanium dioxide support according to the invention by firing at a temperature of 800 ℃.

Figure 3 is a graph comparing the current-voltage performance of the electrode catalyst with different weight ratio of the platinum loading according to the present invention.

4 is a graph showing the current generation duration of the electrode catalyst according to the present invention.

Claims (10)

In the method for producing an electrode catalyst for a fuel cell, Synthesizing a spherical polymer; Adding the synthesized polymer to a mixed solution; Mixing a Ti (SO ₄ ) ₂ solution to the mixed solution to which the polymer is added to form a spherical titanium dioxide support; And A method of manufacturing an electrode catalyst for a fuel cell, comprising: forming an electrode catalyst by supporting a platinum (Pt) catalyst on the titanium dioxide support. The method of claim 1, Synthesizing the spherical polymer Stirring the solution of adding potassium persulfate to distilled water; And Method for producing an electrode catalyst for a fuel cell comprising the step of reacting by adding styrene (methacrylic acid) and styrene (methacrylic acid) to the solution. The method of claim 2, Reacting by adding styrene (meth) and methacrylic acid (methacrylic acid) to the solution A method for producing an electrode catalyst for a fuel cell, characterized in that the nitrogen atmosphere. The method of claim 1, In the step of adding the polymer to the mixed solution The mixed solution is a method for producing an electrode catalyst for a fuel cell, characterized in that formed by adding distilled water, hydrochloric acid and cetytrimethylammonium chloride (cetytrimethylammonium chloride). The method of claim 1, Dropping the Ti (SO ₄ ) ₂ solution to the mixed solution to form a titanium dioxide (Titanium Dioxide) support having a hole (Hole) Forming a mixed solution in which the Ti (SO ₄ ) ₂ solution is dropped into a solid sample; And A method of manufacturing an electrode catalyst for a fuel cell comprising the step of firing the solid sample. The method of claim 5, wherein The firing of the solid sample is a method of manufacturing an electrode catalyst for a fuel cell, characterized in that made in a temperature range of 600 ℃ to 800 ℃. The method of claim 1, The electrode catalyst formed in the step of forming an electrode catalyst by supporting a platinum (Pt) catalyst on the titanium dioxide support is A weight ratio of the platinum catalyst is 20wt% to 60wt%, the manufacturing method of the electrode catalyst for fuel cells. In the electrode catalyst for fuel cells, Spherical polymers; Titanium dioxide (TiO ₂₎ support having a titanium dioxide (TiO ₂₎ formed on the spherical polymer; And Electrode catalyst comprising a platinum (Pt) catalyst supported on the titanium dioxide (TiO ₂ ) support. The method of claim 8, The spherical polymer is an electrode catalyst, characterized in that formed by reacting potassium persulfate, styrene and methacrylic acid. The method of claim 8, The weight ratio of the platinum (Pt) catalyst supported on the titanium dioxide (TiO ₂ ) support is an electrode catalyst, characterized in that 20wt% to 60wt%.

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