KR100747182B1 - Method for preparing catalyst materials for solid electrolyte fuel cell - Google Patents

Abstract

The present invention relates to a method for producing a catalyst material for a solid electrolyte fuel cell, comprising adding sulfur element and carbon black to a solvent, followed by heat treatment, and adding an appropriate amount of ruthenium precursor to the reaction, followed by washing and drying to form a powder-supported sulfide material. And a process of obtaining the final sulfide material crystallized by heat-treating the synthesized powder thereafter, which can be used as both an anode and a cathode electrode catalyst material for a solid electrolyte fuel cell, without ruthenium element The present invention relates to a method for preparing a catalyst material for a solid electrolyte fuel cell, by which a highly dispersed and crystallized sulfide catalyst material having a uniform nanoparticle size of 5 nm can be obtained.

Automotive, solid electrolytes, fuel cells, electrodes, catalysts, sulfides, ruthenium, carbon, high dispersion, crystallization, nanoparticles

Description

Method for preparing catalyst materials for solid electrolyte fuel cell {Method for preparing catalyst materials for solid electrolyte fuel cell}

1 is a diagram of the XRD results obtained when the same heat treatment of the compound of each Example with different Ru / S precursor ratio;

2 is a TEM image showing the structure of a catalyst material according to the present invention,

3 is a catalytic activity analysis result showing the hydrogen oxidation characteristics of the catalyst material according to the present invention.

The present invention relates to a method for preparing a catalyst material for a solid electrolyte fuel cell, and more particularly, by adding elemental sulfur and carbon black to a solvent, followed by heat treatment, and adding an appropriate amount of ruthenium precursor to the reaction, followed by washing and drying to form a powder state. It is composed of a process of synthesizing the supported sulfide material and then the heat treatment of the synthesized powder to obtain the final sulfide material crystallized, it can be used as both the electrode catalyst material of the anode and the cathode for a solid electrolyte fuel cell, platinum The present invention relates to a method for preparing a catalyst material for a solid electrolyte fuel cell, which is capable of obtaining a highly dispersed and crystallized sulfide catalyst material having a uniform nanoparticle size of 5 nm based on ruthenium element without addition.

In general, a fuel cell is a device that converts chemical energy of a fuel into electrochemical energy directly in a cell without being converted into heat by combustion, and is a pollution-free power generation device that has been recently studied with interest. In fuel cells, fuel and oxygen react electrochemically to produce electrical energy. Such fuel cells can be applied not only to supply power for industrial, domestic and vehicle driving, but also for power supply of small electric / electronic products, especially portable devices. The type of fuel cell includes a solid electrolyte fuel cell, a phosphate fuel cell, a molten carbonate fuel cell, and the like depending on the type of electrolyte used. The temperature used and the material used are determined by the characteristics of the electrolyte. Currently, as the power supply for driving a vehicle, the type of solid electrolyte fuel cell has been studied the most, and in the solid electrolyte fuel cell, hydrogen is supplied from the anode and oxygen is supplied from the cathode. Is formed.

Pole oxidation ^{_{reaction: 2H 2 → 4H + + 4e}} -

Reduction electrode ^{_{reaction: O 2 + 4e - + 4H}} + → 2H 2 O

Total reaction: 2H ₂ + O ₂ → 2H ₂ O

As shown in the above reaction scheme, in the anode, hydrogen molecules are decomposed to generate four hydrogen ions and four electrons. The electrons generated here move through an external circuit to form a current, and the generated hydrogen ions move to a cathode through an electrolyte to undergo a cathode reaction. Therefore, since the efficiency of the fuel cell depends largely on the speed of the electrode reaction, a catalyst is used as the electrode material. However, as the catalyst material used in fuel cells is mainly made of platinum (Pt) -based precious metals, the economic burden is bound to increase. It is reported that in order to commercialize fuel cell vehicles, the amount of platinum used per kW should be reduced to 0.2g or less. To this end, a lot of technical difficulties occur, and therefore, many studies have been conducted to overcome the economic difficulties of electrode materials by developing non-platinum materials. Currently, Mo, W-based carbrides (CJ Barnett et al., 1997), RuS ₂ (Hua Zhang et al., 2003), etc. are developed as non-platinum-based anode catalysts, and the cathode material is Perovskite It is a binary sulfide system composed of an oxide system having a structure and Mo and Ru. As such, the material applicable to both the anode and the cathode can be determined as a sulfide system, but there is no example of a uniform and highly dispersed sulfide material having a size of 5 nm.

Therefore, the present invention has been invented to solve the above problems, by adding sulfur element and carbon black to the solvent to heat treatment and adding an appropriate amount of ruthenium precursor to the reaction and then washing and drying to support the powder state It is composed of a process of synthesizing the sulfide material, and then obtaining a final sulfide material crystallized by heat treatment of the synthesized powder, it can be used as both the electrode catalyst material of the anode and the cathode for a solid electrolyte fuel cell, without the addition of platinum It is an object of the present invention to provide a method for preparing a catalyst material for a solid electrolyte fuel cell, which is capable of obtaining a highly dispersed and crystallized sulfide catalyst material having a uniform nanoparticle size of 5 nm based on ruthenium elements.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The present invention provides a method for producing an electrode catalyst material for a solid electrolyte fuel cell,

(a) adding a predetermined amount of elemental sulfur and carbon black to a solvent and heat-treating in nitrogen atmosphere;

(b) Then, a predetermined amount of Ru precursor (Ru ₃ (CO) ₁₂ ) is added in a state of cooling to room temperature, followed by reaction in a nitrogen atmosphere, followed by washing and drying to synthesize a powdered sulfide based on ruthenium element. Obtaining a material;

(c) heat-treating the dried powdery composite to obtain a nanoparticle-sized crystallized final sulfide material as the electrode catalyst material;

Characterized in that comprises a.

In the step (a), xylene (xylene) is used as the solvent.

In the step (a), the elemental sulfur and carbon black are added to the xylene as the solvent, and the heat treatment is performed at 120 ° C. to 140 ° C. for 1 hour in a nitrogen atmosphere.

The sulfur element may be added in such a manner that the amount of sulfur is Ru: S = 1: 1 to 12 in a molar ratio with respect to the amount of ruthenium element.

Then, in the step (b), after the addition of Ru ₃ (CO) ₁₂ characterized in that the reaction for 15 hours to 25 hours at 140 ℃ nitrogen atmosphere.

And, the step (c) is a heat treatment for 30 minutes to 1 hour at 350 ℃ ~ 450 ℃ dried powdered composite after the additional heat treatment for 2 hours to 6 hours at 500 ℃ ~ 800 ℃ It characterized in that to proceed to the two-step heat treatment process.

And, in the step (a), the ratio of carbon black and xylene is characterized in that it is added so that the carbon black per 0.05ml ~ 0.05g ~ 0.25g.

And, in the step (b), the ratio of the Ru precursor and xylene is characterized in that the addition so as to be about 0.05g ~ 0.25g Ru precursor per 100ml xylene.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

The present invention relates to a method for producing a catalyst material for a solid electrolyte fuel cell, and can be applied to both a catalyst of a hydrogen anode and an oxygen reduction electrode for a solid electrolyte fuel cell, and does not add platinum (Pt) to ruthenium (Ru) elements. An object of the present invention is to provide a sulfide catalyst material for a solid electrolyte fuel cell.

Sulfide materials are known as materials having electrical conductivity and catalytic activity.

The present invention is to provide a material of the electrode catalyst for a solid electrolyte fuel cell by controlling the nano-sulfide-based material of the sulfide system based on ruthenium, which does not contain platinum material, to high particle size and control the nanoparticle size.

That is, the present invention provides a highly dispersed and crystallized nano particle size sulfide material as an electrode catalyst material.

This manufacturing method of the present invention will be described in more detail.

In the manufacturing process of the electrode catalyst material for a solid electrolyte fuel cell according to the present invention, a process of synthesizing a supported sulfide material using a support material which can be used for a fuel cell is large, and then heat-treating the synthesized powder to uniform the average particle size of 5 nm. The process proceeds to obtain the final sulfide material with a nanoparticle size and highly dispersed and crystallized.

First, the sulfide material synthesis process will be described, but xylene (xylene) is used as a solvent, but xylene is used to remove the gas dissolved in the solvent using a vacuum pump before use.

Subsequently, elemental sulfur and carbon black are added to xylene and heat treated at 120 ° C. to 140 ° C. for 1 hour in a nitrogen atmosphere. This heat treatment dissolves sulfur in a solvent and carbon in a solvent. Implement to disperse well.

At this time, the ratio of carbon black and xylene is preferably added so as to be about 0.05 g to 0.25 g of carbon black per 100 ml of xylene.

Here, when the carbon black is less than 0.05g per 100 ml of xylene, there is a problem that the economic efficiency is lowered due to the use of excess solvent, and when the carbon black is added in excess of 0.25g, the carbon black may not be well dispersed in the solvent. Not.

In addition, carbon black and sulfur are preferably heat-treated in xylene at 120 ° C to 140 ° C. If the temperature is less than 120 ° C, sulfur may not be completely dissolved in the solvent. Due to the high temperature, there is a problem of low economic efficiency, which is not preferable.

Subsequently, after cooling to room temperature, Ru ₃ (CO) ₁₂ , which is a Ru precursor, was added thereto, followed by reaction for 15 hours to 25 hours at 140 ° C. in a nitrogen atmosphere, and then washed with acetone, followed by drying at 70 ° C.

At this time, the ratio of the Ru precursor and the xylene is preferably added so that the Ru precursor is about 0.05g ~ 0.25g per 100ml of xylene.

Here, when the Ru precursor is less than 0.05g per 100 ml of xylene, there is a problem in that the economical efficiency is lowered due to the use of excess solvent, and when added in excess of 0.25g, the physical properties of the final powder are changed due to the high concentration of the Ru precursor. There is a problem, which is undesirable.

In addition, the reaction time after the addition of the Ru precursor is preferably 15 hours to 25 hours, if less than 15 hours, there is a problem that carbon black and sulfur does not form a compound with the Ru precursor, exceeding 25 hours In this case, there is a problem that the efficiency is lowered due to a long reaction time, which is not preferable.

At this time, the elemental sulfur is preferably added so that the amount of Ru: S = 1: 2 to 12 in a molar ratio with respect to the amount of ruthenium element used.

Here, when the sulfur element is added less than 2 times the amount of ruthenium element used, there is a problem in that the molar ratio is not corrected due to the loss of sulfur during the heat treatment process. There is a problem that sulfur cannot be removed, which is not preferable.

Next, the powdered composite compound dried as described above is heat treated to obtain a sulfide material having a uniform nano particle size that is highly dispersed and crystallized.

In the present invention, the heat treatment process for crystallization proceeds to a two-step heat treatment process, first heat treatment of the first step for 30 minutes to 1 hour at 350 ℃ ~ 450 ℃, then 2 hours ~ 6 at 500 ℃ ~ 800 ℃ The second stage of heat treatment is performed during the time.

In the first step of the heat treatment process, the heat treatment temperature is preferably 350 ℃ ~ 450 ℃.

If the temperature is 350 ° C., sulfur may not form a Ru precursor and a compound well. If the temperature is higher than 450 ° C., sulfur may evaporate and be lost, which is not preferable.

In the first step of heat treatment, the heat treatment time is preferably 30 minutes to 1 hour.

If it is less than 30 minutes, there is a problem that sulfur does not form a compound well with Ru precursor, and if it exceeds 1 hour, there is a problem that the efficiency decreases with a long reaction time, which is not preferable.

In the second step of heat treatment, the heat treatment temperature is preferably 500 ° C. to 800 ° C.

If the temperature is less than 500 ° C, there is a problem in that the sulfide is not crystallized well. If the temperature is higher than 800 ° C, the sulfide crystals become large, which is not preferable.

In the second step of heat treatment, the heat treatment time is preferably 2 hours to 6 hours.

In the case of less than 2 hours, there is a problem in that the sulfide is not crystallized well, and in the case of more than 6 hours, there is a problem in that the sulfide crystal becomes large, which is not preferable.

The heat treatment of the first step is carried out to form Ru and the compound well at a temperature before the loss of sulfur, and the heat treatment of the second step is carried out to crystallize the sulfide, and thus divided into two steps to proceed the heat treatment The molar ratio of Ru and sulfur can achieve the effect of synthesizing accurate crystallized sulfide.

Thus, according to the production method of the present invention, it can be used as both the electrode catalyst material of the oxidizing electrode and the reducing electrode for a solid electrolyte fuel cell, and has a uniform nanoparticle size of 5 nm based on ruthenium element without adding platinum. A dispersed and crystallized sulfide catalyst material can be obtained.

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

Example  And Comparative example

As an example, a sulfide catalyst material based on ruthenium element was prepared without using platinum according to the production method of the present invention.

As Example 1, 0.15 g of elemental sulfur and 0.12 g of carbon black were first added to 80 ml of xylene in a gas-free state, and then heat-treated at 140 ° C. for 1 hour in a nitrogen atmosphere.

After cooling to room temperature, 0.1 g of Ru ₃ (CO) ₁₂ , a precursor of Ru, was added thereto, and reacted at 140 ° C. for 20 hours in a nitrogen atmosphere, followed by washing with acetone and drying at 70 ° C.

Here, the amount of elemental sulfur used is 10 times (Ru: S = 1: 1) in molar ratio with respect to the amount of elemental ruthenium.

Subsequently, in order to crystallize the dried powdered composite as described above, the first step of heat treatment was performed at 400 ° C. for 30 minutes, and then the second step of heat treatment was performed at 500 ° C. for 4 hours. The sulfide material for producing an electrode catalyst highly dispersed in nanoparticle size was obtained.

Next, as Example 2, Example 3, and Example 4, a sulfide material was manufactured by the same process as in Example 1, except that only sulfide materials were used, thereby obtaining a sulfide material.

That is, in Example 2, the amount of elemental sulfur was 0.06 g, and the amount of the elemental sulfur was four times the molar ratio relative to the amount of ruthenium element. In Example 3, the amount of elemental sulfur was 0.09 g. The molar ratio was 6 times, and in Example 4, the amount of elemental sulfur was 0.12 g, and the amount of elemental sulfur was 8 times the molar ratio.

Next, as Comparative Example 1, 20 wt% Pt / C [E-TEK] commercialized was prepared.

Test Example

As a result of structural analysis on the heat treated sulfide materials of Examples 1 to 4, the higher the amount of sulfur element added, the higher the crystallinity under the same heat treatment conditions. For Example 1, which was 10 times higher, it was confirmed that a highly dispersed and crystallized sulfide material having an average particle of 5 nm was obtained.

FIG. 1 is a diagram of the XRD results obtained when the compounds of the Examples having different Ru / S precursor ratios were subjected to the same heat treatment.

In this XRD result, it is possible to roughly determine whether the material is synthesized and the particle size based on the position of the peak.

Peaks that may appear in these tests are those of Ru, S, and RuSx.

However, the Ru and RuSx peak analysis can also be used to determine whether RuSx is synthesized.In the case of Ru, the highest intensity peak appears at 2θ near 44 degrees, and in the case of RuSx, the 2θ values are 27, 31, Strong peaks appear near 45 and 54 degrees.

In Example 2 ([1-4]), the strongest peak appeared near 44 degrees.

This means that Ru is crystallized, and from Example 3 ([1-6]), a complex peak appears, and it can be seen that the peak of RuSx starts to appear mainly in Example 4 ([1-8]).

In Example 1 ([1-10]), the peak of RuSx appears clearly.

FIG. 2 is a transmission electron microcope (TEM) image for structural analysis of a supported sulfide material, which shows the sulfide material of the embodiment, and in the case of the embodiment, the average particle size of the sulfide material has a uniform size of 5 nm. It was analyzed.

Next, the electrochemical activity evaluation of hydrogen oxidation was performed using the electrode using the material of the said Example 1 and the comparative example 1, The evaluation method is as follows.

In the electrochemical activity evaluation, a hydrogen symmetry cell (H ₂ -symmetry cell) was used, and this method is described in detail. The platinum paper is coated on carbon paper and the material to be evaluated on carbon paper is coated. After the preparation, the MEA was prepared by using electrolyte Nafion, and hydrogen was flowed to both sides, and the Pt material contained was set as the reference electrode, and the side to be evaluated was set as the working electrode. The catalytic activity of the material was evaluated by measuring the current resulting from hydrogen oxidation at the potential.

As a result of the catalytic activity analysis, Figure 3 is a result showing the hydrogen oxidation characteristics, it was found that the pure RuSx material (example) showed 8.92% of the activity compared to the platinum catalyst.

3 is a curve obtained by flowing hydrogen to the reference electrode side and nitrogen instead of hydrogen to the working electrode side in the analytical material of the lowermost part of FIG. 3, and a comparison object is a comparison between two upper lines.

An activity level of 8.92% means that platinum-like performance can be achieved by using 10 times less expensive RuSx / C without Pt.

This activity level is a level suitable for the purpose to achieve a value that can vary from 5% level by the properties of the material adjusted to the synthesis method.

As described above, according to the method for preparing a catalyst material for a solid electrolyte fuel cell according to the present invention, elemental sulfur and carbon black are added to a solvent for heat treatment, and an appropriate amount of ruthenium precursor is added thereto, followed by washing and drying. It is composed of a process of synthesizing the powdered supported sulfide material, and then heat-treating the synthesized powder to obtain the final sulfide material crystallized, so that it can be used as both the electrode catalyst material of the anode and the cathode for a solid electrolyte fuel cell. Without the addition of platinum, it is possible to obtain a highly dispersed and crystallized sulfide catalyst material having a uniform nanoparticle size of 5 nm based on ruthenium element.

Claims (8)

In the method for producing an electrode catalyst material for a solid electrolyte fuel cell, (a) elemental sulfur and carbon black are added to xylene, and the elemental sulfur is added such that the amount of Ru is used in a molar ratio relative to the amount of ruthenium element Ru: S = 1: 2 to 12 , The ratio of the carbon black and xylene is heat-treated in a nitrogen atmosphere by adding 0.05g to 0.25g of carbon black per 100ml of xylene; (b) Then, Ru ₃ (CO) ₁₂ , which is a Ru precursor, is added in a state of cooling to room temperature, and the ratio of the Ru precursor and xylene is reacted in a nitrogen atmosphere after adding 0.05 g to 0.25 g of Ru precursor per 100 ml of xylene. Obtaining a powdered sulfide material based on ruthenium element after washing and drying; (c) heat-treating the dried powdered composite to obtain a nano-sized crystallized final sulfide material as the electrode catalyst material; Method for producing an electrode catalyst material for a solid electrolyte fuel cell, characterized in that comprises a. delete The method according to claim 1, In the step (a), the sulfur element and carbon black is added to the xylene as a solvent and heat treatment at a temperature of 120 ℃ ~ 140 ℃ for 1 hour in a nitrogen atmosphere, characterized in that the manufacturing method of the electrode catalyst material for a solid electrolyte fuel cell . delete The method according to claim 1, In the step (b), after the addition of Ru ₃ (CO) ₁₂ and the reaction method for the electrode catalyst material for a solid electrolyte fuel cell, characterized in that for 15 hours to 25 hours at 140 ℃ nitrogen atmosphere. The method according to claim 1, In step (c), the dried powdered composite is heat treated at 350 ° C. to 450 ° C. for 30 minutes to 1 hour, and then further heat treated at 500 ° C. to 800 ° C. for 2 hours to 6 hours. Method for producing an electrode catalyst material for a solid electrolyte fuel cell, characterized in that the step of heat treatment. delete delete

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