KR20170054145A - Catalyst, manufacturing method of the same and fuel cell comprising the same - Google Patents

Abstract

The present invention relates to a catalyst, a production method thereof, and a fuel cell including the same. According to the present invention, the catalyst is able to prevent aggregation of metal and corrosion on carbon supports and creates a catalyst activation area, by forming a protective layer which contains nitrogen-doped carbon materials on a metal-supported carbon support, thereby increasing performance of batteries having a catalyst-containing catalytic layer owing to superior durability.

Description

TECHNICAL FIELD The present invention relates to a catalyst, a method for producing the same, and a fuel cell including the catalyst,

The present invention relates to a catalyst, a method for producing the same, and a fuel cell including the same.

Platinum was mainly used as a catalyst for a conventional polymer electrolyte membrane fuel cell. Commercial platinum was used in the form of nano-sized platinum particles deposited on a carbon support such as a carbon material to increase the effective area of the catalyst.

However, as the fuel cell runs, the agglomeration of the platinum particles progresses due to the aggregation of the platinum particles and the agglomeration of the carbon support through the dissolution-redeposition process. This loss is fundamentally explained by the thermodynamic nature of platinum dissolving via oxygen species.

Carbon becomes thermodynamically prone to oxidize to form surface oxides when the potential is above the standard voltage of 0.207V. As a solution to this problem, research is being conducted on a functional support doped with carbon or the like.

The nitrogen-doped carbon support is improved in wettability and hydrophilicity, so that the metal catalyst particles can be more uniformly dispersed and smaller. Furthermore, in an effort to increase the durability of the catalyst, research has recently been conducted to cover a thin protective layer on the catalyst including the metal particles and the support. At this time, since reactants must be supplied to the surface of the metal catalyst, it is an issue to thinly cover the porous material with SiO ₂ as a porous material.

For example, there is a research result of SiO ₂ coating on Pt / CNF in Kyushu region. The performance of the three-electrode system was similar to that of the commercial Pt / C in the half cell test, but was lower than that of the commercial Pt / C in the single cell test.

Therefore, there is a need for research to minimize the performance deterioration while preventing the platinum from being clustered.

U.S. Published Patent Application No. 2015-0196897

The present invention relates to a catalyst, a method for producing the same, and a fuel cell including the same, and aims at improving the existing slow oxygen reduction reaction rate of the battery and realizing excellent durability.

The present invention relates to a catalyst, a method for producing the same, and a fuel cell including the catalyst,

A metal-supported carbon support; And

A catalyst comprising a protective layer comprising a carbon-doped carbonaceous material formed on a metal-supported carbon support can be provided.

In addition, as an example of the method for producing the catalyst,

Preparing a catalyst having a protective layer containing a carbon-doped carbon material on a metal-supported carbon support; And

And a step of heat treating the prepared catalyst.

In addition, the present invention can provide a battery having a catalyst layer containing the catalyst.

The catalyst according to the present invention can form a protective layer containing carbon-doped carbonaceous material on a metal-supported carbonaceous support, thereby preventing the corrosion of the carbonaceous support and the aggregation of metals, thereby realizing a catalytic active area, And the performance of the battery having the catalyst layer formed thereon can be improved.

Figure 1 is a TEM photograph of the catalyst prepared in one embodiment.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

In the present invention, the terms "comprising" or "having ", and the like, specify that the presence of a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

Hereinafter, the present invention will be described in detail.

The present invention relates to a catalyst, a method for producing the same, and a battery including the same,

A metal-supported carbon support; And

A catalyst comprising a protective layer comprising a carbon-doped carbonaceous material formed on a metal-supported carbon support can be provided.

Specifically, by forming a protective layer containing a carbon material doped with nitrogen on a metal-supported carbon support, it is possible to prevent the corrosion of the carbon support and the metal aggregation, thereby realizing a catalytic active area. The performance and durability of the battery in which the catalyst layer including the catalyst layer is formed can be improved.

The carbon support may include at least one of carbon black, ketjen black, graphite, carbon nanotube, carbon nanocage, and carbon fiber. By using the above-mentioned carbon support, degradation of the mechanical properties of the catalyst can be prevented.

The metal may be a transition metal. For example, the transition metal may include Pt, V, Ti, Cr, Mn, Fe, Co, Ni, Cu, Sn, Nb, Mo, Pd and Ag. Specifically, the metal may be platinum (Pt). By depositing platinum on the carbon support, the active area of the catalyst can be increased.

The protective layer comprising the nitrogen-doped carbonaceous material may comprise at least one selected from the group consisting of dicyandiamide (DCDA), tetrazole, aminotetrazole, methylamine, guanidine, methylhydrazine methyl hydrazine, acetonitrile, triazole, dimethylamine, ethylamine, dimethyl hydrazine, ethylenediamine, triazine, acrylonitrile, And may be formed using at least one of acrylonitrile, pyrazole, melamine, pyrrole, and pyridine.

Specifically, the protective layer may be formed using ethylenediamine.

By forming a protective layer containing carbon-doped carbonaceous material on the metal-supported carbonaceous support using ethylenediamine, the wettability and the hydrophilicity of the carbonaceous support are improved so that the catalyst particles are more uniformly dispersed to widen the catalytic active area And furthermore, the durability of the catalyst can be improved by preventing the corrosion of carbon.

The average diameter of the catalyst may be between 1 and 500 mu m. For example, the average diameter of the catalyst may range from 1 to 400 mu m, from 10 to 400 mu m, or from 100 to 300 mu m. The catalyst according to the present invention satisfies the average diameter within the above range, so that when the catalyst layer is formed using the catalyst, excellent coating properties can be realized.

The average thickness of the protective layer may be 0.1 to 5 nm. For example, the thickness of the protective layer may range from 0.1 to 4 nm, from 0.5 to 4 nm, or from 1 to 3 nm. The thickness of the protective layer may vary depending on the content of the protective layer forming material. For example, . By forming the protective layer thin on the metal-supported carbon support as described above, the durability can be improved without lowering the activity of the catalyst.

As one example of the method for producing the catalyst according to the present invention,

Preparing a catalyst having a protective layer containing a carbon-doped carbon material on a metal-supported carbon support; And

And a step of heat treating the prepared catalyst.

The step of preparing a catalyst in which a protective layer containing carbon-doped carbon material is formed on the metal-

Preparing a suspension by refluxing an aqueous solution containing a metal-supported carbon support and a protective layer-forming material;

Filtering the suspension; And

And drying the filtered catalyst.

For example, in the step of preparing a suspension by refluxing an aqueous solution containing a metal-supported carbon support and a protective layer-forming material, the metal-supported carbon support is a commercially available 20 wt% Pt / C (HISPEC, A Johnson Matthey Company) can be used. As an aqueous solution containing a protective layer forming material, an aqueous solution of ethylenediamine can be used.

As an example, a suspension in which a catalyst in which Pt / C and an aqueous solution of ethylenediamine are mixed and refluxed and stirred to form a protective layer containing a carbon material doped with nitrogen on Pt / C is dispersed, The filtrate can be washed with distilled water and ethanol using a vacuum filtration apparatus. The thus-filtered catalyst can be dried in an oven at a temperature of 40 to 80 DEG C for 5 to 10 hours to obtain a powdery catalyst.

The catalyst thus prepared can be heat-treated at a temperature of 400 to 700 ° C. For example, the heat treatment temperature may be performed at a temperature of 400 to 700 ° C or 400 to 500 ° C.

The heat treatment may be performed in an inert gas atmosphere. The inert gas may be at least one of nitrogen, helium, argon, neon, krypton, xenon, and radon. For example, the heat treatment step may be performed under an argon atmosphere. Further, the heat treatment step may be performed for 1 to 3 hours. Through the heat treatment step, a protective layer including a carbon material doped with nitrogen on the catalyst can be formed with strong bonding force.

The Pt / C catalyst (ED treated 20% Pt / C) having a protective layer formed of nitrogen-doped carbonaceous material according to the present invention manufactured through the above process is excellent in preventing corrosion of a superior carbon support and aggregation of metals Thereby realizing a catalytic active area, and excellent durability.

The present invention can provide a fuel cell in which a catalyst layer containing the catalyst is formed. At this time, the type and structure of the fuel cell are not particularly limited.

For example, the fuel cell may be a membrane electrode assembly formed with a catalyst layer using the catalyst according to the present invention. The membrane electrode assembly may include a polymer electrolyte membrane; And an anode electrode and a cathode electrode. At least one of the anode electrode and the cathode electrode may be formed with a catalyst layer using the catalyst according to the present invention.

The fuel cell supplies 100 sccm of hydrogen and 150 sccm of oxygen to the electrode, and when operated under the conditions of a temperature of 75 캜, a relative humidity of 100% and 1 atm,

The current density (0.6 V) may be 1400 mA / cm ^{2 or} more.

For example, the current density is 1400 to 2000 mA / cm ^2, 1400 to 1900 mA / cm ² or 1500 to 1850 mA / cm ² . As a result, it can be confirmed that the catalyst according to the present invention exhibits excellent catalytic activity.

In the fuel cell, 150 sccm of nitrogen was supplied to the electrode, and 10000 cycles were performed through potential sweeping in the range of 0.6 to 1 V under conditions of a temperature of 75 캜 and a relative humidity of 100%

The rate of change of the chemically active area may be less than 50%.

Specifically, when 10,000 cycles are carried out in a high-temperature and high-humidity environment, the rate of change of the chemically active area may be in the range of, for example, 10 to 50%, 35 to 50%, or 40 to 50%.

The fuel cell according to the present invention satisfies relatively low chemical activity area change ratio within the above-mentioned range, and thus it can be confirmed that the fuel cell has excellent durability even in a high temperature and high humidity environment.

Hereinafter, the present invention will be described in more detail with reference to the following Examples. However, the scope of the present invention is not limited by the following Examples.

Example  1 to 4: catalyst preparation

0.1 g of a 20 wt% Pt / C (HISPEC, A Johnson Matthey company) catalyst was mixed with 100 ml of an aqueous solution of ethylenediamine, and the mixture was refluxed at 75 ° C for 8 hours. Then, the suspension containing the catalyst and the aqueous solution of ethylenediamine was rinsed with distilled water and ethanol using a reduced pressure filtration apparatus, filtered, and then dried in an oven at 60 ° C for 8 hours. Then, the powdery catalyst was recovered. The dried catalyst was heat-treated for 2 hours in a heating furnace in an argon gas atmosphere to obtain a Pt / C catalyst (ED treated 20% Pt / C) formed with a 1 nm thick protective layer containing nitrogen- .

At this time, the heat treatment temperature was adjusted as shown in Table 1 below.

Heat treatment temperature (캜) Example 1 400 Example 2 500 Example 3 600 Example 4 700

A TEM photograph of the catalyst prepared in Example 1 is shown in FIG. 1, it is confirmed that a protective layer is formed of ethylenediamine on 20 wt% Pt / C.

Comparative Example

A commercially available 20 wt% Pt / C (HISPEC, A Johnson Matthey Company) was used as the catalyst.

Experimental Example  1: Measurement of catalytic properties

One) CHNS  Analysis experiment

Elemental analysis experiments for carbon, hydrogen and nitrogen were carried out using the catalysts prepared in Examples 1 to 4 and Comparative Examples. The results are shown in Table 2 below.

C (%) H (%) N (%) Total (%) Example 1 73.71 0.29 0.23 74.23 Example 2 72.68 0.12 0.18 72.98 Example 3 76.68 0.11 0.16 76.95 Example 4 74.19 0.00 0.09 74.28 Comparative Example 74.31 0.51 0.00 74.82

Referring to Table 2, it can be seen that the catalyst prepared in the example according to the present invention is formed of ethylenediamine containing nitrogen as a protective layer, thereby confirming nitrogen element.

2) XPS  Analysis experiment Pt )

XPS analysis experiments on platinum were performed using the catalysts prepared in Examples 1 to 4 and Comparative Examples. The results are shown in Table 3 below.

Pt metal (%) Pt oxide (%) Example 1 78.66 21.34 Example 2 79.75 20.25 Example 3 77.17 22.83 Example 4 78.57 21.43 Comparative Example 75.47 24.53

Referring to Table 3, it can be seen that the catalyst prepared in the example according to the present invention has a higher proportion of platinum metal than platinum oxide as compared with the comparative example. As a result, it can be seen that the catalyst according to the present invention can reduce the amount of platinum to be used, thereby ensuring price competitiveness.

3) XPS  Analysis (N)

XPS analysis experiments for nitrogen were carried out using the catalysts prepared in Examples 1 to 4 above. The results are shown in Table 4 below.

Example 1 Example 2 Example 3 Example 4 Pyridinic-N 53.40 54.06 32.91 32.34 Pyrrolic-N 25.12 18.86 32.56 28.74 Graphitic-N 14.84 24.50 28.07 31.66 Oxidized-N 6.64 2.58 6.46 7.26

Referring to Table 4, it can be seen that the catalyst prepared in the example according to the present invention changes the nitrogen bond structure according to the heat treatment temperature.

Experimental Example  2: Evaluation of fuel cell characteristics

A membrane electrode assembly of a polymer electrolyte fuel cell (PEMFC) having a catalyst layer formed using the catalysts prepared in Examples 1 to 4 and Comparative Examples was prepared. Specifically, a cell was fabricated by forming a structure in which a protective layer containing a carbon material doped with nitrogen was laminated on both sides of a polymer electrolyte membrane, and a gas diffusion layer (Fas diffusion layer) was bonded to both sides of the protective layer.

The characteristics of each of the fuel cells thus manufactured were evaluated, which is specifically described below.

1) Current density measurement

The current density was measured when each of the fuel cells was operated under the conditions of supplying 100 sccm of hydrogen and 150 sccm of oxygen to the electrode and operating under the conditions of a temperature of 75 캜, a relative humidity of 100% and 1 atm. The results are shown in Table 5 below.

Current density (mA / cm ² ) Example 1 1804 Example 2 1788 Example 3 1555 Example 4 1521 Comparative Example 1280

Referring to Table 5, it can be seen that the current density of the fuel cell according to the comparative example is about 1280 mA / cm ² , and that the battery according to the present invention has a current density of 1500 mA / cm ² or more. mA / cm < ² >, respectively.

As a result, it can be seen that the fuel cell according to the present invention exhibits a catalytic activity of about 40% or more even in a high temperature and high humidity environment, compared with the comparative example.

2) Cycle performance measurement

Using each of the fuel cells thus prepared, 15000 sccm of nitrogen was supplied to the electrode, and 10,000 cycles were performed through potential sweeping in the range of 0.6 to 1 V at a temperature of 75 캜 and a relative humidity of 100%. At this time, the rate of change of the catalytic active area before and after the cycle was measured. The results are shown in Table 6 below.

Change in Catalytic Active Area (%) Example 1 48.8 Example 2 46.5 Example 3 43.2 Example 4 40.7 Comparative Example 78.39

Referring to Table 6, it was confirmed that the catalyst according to the present invention was 50% or less as compared with the catalyst active area change ratio of the fuel cell according to the comparative example being 78.39%.

As a result, it was found that the fuel cell according to the present invention exhibited less decrease in catalytic active area even when it was used for a long time in a high temperature and high humidity environment, as compared with the comparative example. This is directly related to the performance of the fuel cell, which means that the durability of the battery is excellent.

Claims (10)

A metal-supported carbon support; And
A catalyst comprising a protective layer comprising a carbon-doped carbonaceous material formed on a metal-supported carbon support.
The method according to claim 1,
Wherein the carbon support comprises at least one of carbon black, ketjen black, graphite, carbon nanotube, carbon nanocage and carbon fiber.
The method according to claim 1,
Wherein the metal is a transition metal.
The method according to claim 1,
Wherein the catalyst has an average diameter of 1 to 500 mu m.
The method according to claim 1,
Wherein the average thickness of the protective layer is 0.1 to 5 nm.
Preparing a catalyst having a protective layer containing a carbon-doped carbon material on a metal-supported carbon support; And
And heat treating the prepared catalyst.
The method according to claim 6,
And the heat treatment temperature is 400 to 700 占 폚.
A fuel cell comprising a catalyst layer comprising the catalyst according to claim 1.
9. The method of claim 8,
When the electrode is supplied with 100 sccm of hydrogen and 150 sccm of oxygen and operating under the conditions of a temperature of 75 캜, a relative humidity of 100% and 1 atm,
A fuel cell having a current density (0.6 V) of 1400 mA / cm ² or more.
9. The method of claim 8,
150 sccm of nitrogen was supplied to the electrode and 10000 cycles were performed through potential sweeping in the range of 0.6 to 1 V at a temperature of 75 캜 and a relative humidity of 100%
Wherein the rate of change of the chemical active area is 50% or less.

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