JP2005050734A - Manufacturing method of electrode for solid polymer fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a PEFC electrode in which a platinum metal exists mainly in the interface of the surface of carbon particles and ion cluster portion of a cation exchange resin and in which the platinum metal in the PEFC electrode is increased and the utilization factor of the platinum metal is improved by solving a problem that binding force between the surface of the carbon particles and the cation exchange resin is not sufficient. <P>SOLUTION: The manufacturing method of a PEFC electrode includes a process in which a mixture containing carbon particles and a cation exchange resin is heated at a temperature of glass transition temperature or more and decomposition temperature or less of the cation exchange resin, and then, cations containing a platinum metal element are adsorbed to the cation exchange resin contained in the above mixture, and then the cations are reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a polymer electrolyte fuel cell electrode.

  In order to reduce the cost of a polymer electrolyte fuel cell (PEFC), Patent Document 1 discloses an electrode for a fuel cell having high performance with a very small amount of platinum group metal.

JP 2000-12041 A.

  The platinum group metal of this electrode exists mainly on the contact surface between the surface of the carbon particles and the ion cluster portion of the cation exchange resin. The conventional manufacturing method of this electrode is as follows. First, a paste of a solution of carbon particles and a cation exchange resin is applied on an FEP film substrate and then dried to produce a sheet of a mixture of carbon particles and a cation exchange resin on the substrate. .

  Next, the sheet of the mixture is immersed in an aqueous solution of a cation containing a platinum group metal element. In this step, a cation containing a platinum group metal element is adsorbed on the ion cluster portion of the cation exchange resin. This adsorption proceeds by an ion exchange reaction between a counter ion of a cation exchange group constituting an ion cluster portion and a cation containing a platinum group metal element.

  Furthermore, after the sheet having undergone this step is dried, it is allowed to stand in an atmosphere of about 180 ° C. containing hydrogen gas. In this step, among the cations containing platinum group metal elements adsorbed on the ion clusters, those existing in the vicinity of the surface of the carbon particles are preferentially reduced, so that the platinum group metal is separated from the surface of the carbon particles. It is deposited on the contact surface with the ion cluster part of the cation exchange resin. A sheet of the mixture that has undergone this stationary step is used as the catalyst layer of the electrode. By laminating the catalyst layer and the gas diffusion layer, an electrode for a fuel cell can be obtained.

  The conventional manufacturing method for electrodes in which the platinum group metal exists mainly on the contact surface between the surface of the carbon particles and the ion cluster portion of the cation exchange resin has sufficient binding force between the surface of the carbon particles and the cation exchange resin. There was a problem caused by not.

  For example, in the step of immersing a sheet of a mixture of carbon particles and a cation exchange resin in a cation aqueous solution containing a platinum group metal element, the cation exchange resin contained in the mixture sheet is swollen by moisture in the aqueous solution. Therefore, it has been a problem that a part of the cation exchange is separated from the surface of the carbon particles. When this delamination occurs, the total area of the contact surface between the surface of the carbon particles and the ion cluster of the cation exchange resin decreases, and as a result, the amount of platinum group metal deposited on the sheet of the mixture decreases.

  In addition, the following problem was also encountered in the process of leaving a sheet of a mixture of carbon particles and cation exchange resin in an atmosphere of about 180 ° C. containing hydrogen gas. In this step, the cation exchange resin contained in the mixture sheet is heated to about 180 ° C. Since this temperature is higher than the glass transition temperature of the resin, the cation exchange resin expands or contracts during this process. Due to this expansion or contraction, a part of the deposited platinum group metal is covered with the fluorocarbon skeleton portion of the cation exchange resin, and as a result, the utilization rate of the platinum group metal has been problematic.

  The invention of claim 1 is a method for producing an electrode for a polymer electrolyte fuel cell for solving the above-mentioned problems, and the feature of this production method is that a mixture containing carbon particles and a cation exchange resin is used. Then, after heating at a temperature not lower than the glass transition temperature and not higher than the decomposition temperature of the cation exchange resin, the cation exchange resin contained in the mixture is adsorbed with a cation containing a platinum group metal element, and then the cation is absorbed. It includes a step of reducing.

  Here, the process of heating the mixture containing the carbon particles and the cation exchange resin at a temperature not lower than the glass transition temperature and not higher than the decomposition temperature of the cation exchange resin is referred to as a “heating process”, and the carbon particles and the cation. The process of adsorbing a cation containing a platinum group metal element to the cation exchange resin contained in the mixture containing the exchange resin is called “adsorption process”, and the process of reducing the cation adsorbed on the cation exchange resin is called “reduction” Process.

  ADVANTAGE OF THE INVENTION According to this invention, the platinum group metal in the electrode for polymer electrolyte fuel cells can be increased, and also the utilization factor of a platinum group metal can be improved. Therefore, the amount of carbon particles, cation exchange resin, and platinum group metal used can be greatly reduced, and a low-cost solid polymer fuel cell can be provided.

  In the method for producing an electrode for a polymer electrolyte fuel cell (PEFC) of the present invention, the mixture containing the carbon particles and the cation exchange resin is at a temperature not lower than the glass transition temperature of the cation exchange resin and not higher than the decomposition temperature. It goes through a “heating process” to be heated. By passing through this heating step, the binding force between the carbon particles and the cation exchange resin increases. This increase in binding force is thought to be due to the improvement in the stability of the crystal structure of the cation exchange resin or / and the improvement in the adhesion between the surface of the carbon particles and the cation exchange resin.

  The mixture containing the carbon particles and the cation exchange resin that has undergone this heating process has a higher binding strength between the carbon particles and the cation exchange resin than the case in which this heating process has not been performed. In the process performed subsequent to the process, the separation of the cation exchange resin from the surface of the carbon particles and the expansion and contraction of the resin are greatly suppressed as compared with the conventional manufacturing method.

  In the electrode manufactured using the manufacturing method of the present invention, the separation of the cation exchange resin from the surface of the carbon particles was suppressed, so that the contact surface between the surface of the carbon particles and the ion cluster of the cation exchange resin was the conventional one. It is larger than that of the electrode when the manufacturing method is used. Since this contact surface is where white metal metal is deposited, the amount of platinum group metal produced using the production method of the present invention is greater than that of the electrode produced using the conventional production method.

  In addition, since the electrode manufactured using the manufacturing method of the present invention suppresses the expansion / contraction of the cation exchange resin, the platinum group metal covered with the fluorocarbon skeleton portion of the cation exchange resin is different from the conventional manufacturing method. Compared to that of the electrode when used, the utilization rate of the platinum group metal in the electrode is improved.

  In the present invention, as a method of heating a mixture containing carbon particles and a cation exchange resin at a temperature not lower than the glass transition temperature and not higher than the decomposition temperature of the cation exchange resin, carbon particles and cation exchange may be used. There is a method in which the temperature of the atmosphere in the furnace is set to the glass transition temperature or more and the decomposition temperature or less after the mixture with the resin is placed in a heating furnace.

  By setting the temperature for heating the mixture to be equal to or lower than the decomposition temperature of the cation exchange resin, the deterioration of the cation exchange resin can be prevented. The inside of the furnace may be an air atmosphere, but in order to prevent deterioration of the cation exchange resin, an atmosphere mainly containing an inert gas such as nitrogen gas, helium gas, neon gas or argon gas is preferable.

  Moreover, in this invention, in order to prevent the fall of the ion exchange capacity of a cation exchange resin, you may heat the mixture containing a carbon particle and a cation exchange resin in the liquid atmosphere containing water. Furthermore, in the present invention, in order to prevent a decrease in the moisture content of the cation exchange resin, after replacing the counter ion of the cation exchange resin in the mixture with a cation other than protons, the carbon particles and the cation exchange resin It is preferable to heat the mixture containing.

  Although any cation can be used here, the effect of the present invention is obtained, but since the effect of preventing a decrease in moisture content is high or easy to handle, lithium ion, sodium ion, calcium Ions, magnesium ions, potassium ions and ammonium ions are preferred.

  In the present invention, the adsorption step of adsorbing a cation containing a platinum group metal element on a cation exchange resin of a mixture containing carbon particles and a cation exchange resin that has undergone a heating step is, for example, a carbon particle and a cation exchange resin. It is carried out by immersing the mixture with the ion exchange resin in an aqueous solution of a cation containing a platinum group metal element.

  The adsorption of the cation containing the platinum group metal element in this adsorption process is based on the use of an ion exchange reaction between the cation and the counter ion of the ion exchange group constituting the ion cluster of the cation exchange resin. preferable. The cation of the platinum group metal element that can be used in the present invention is a cation that can be a catalyst of a white metal metal produced by reducing the cation. Examples of such a cation include a cation containing a metal element such as platinum, rhodium, ruthenium, iridium, palladium, and osnium.

  In particular, since a catalytic metal having high catalytic activity for electrochemical oxygen reduction reaction or hydrogen oxidation reaction is obtained, a cation containing a platinum group metal element is adsorbed, and magnesium, aluminum, vanadium, chromium, Cations containing manganese, iron, cobalt, nickel, copper, zinc, silver or tungsten may be adsorbed.

Furthermore, it is preferable that the cation of the catalytic metal element used in the production method of the present invention is adsorbed on the ion exchange group of the cation exchange resin in the mixture by an ion exchange reaction. As a cation containing a platinum group metal element having such adsorption characteristics, a complex cation of a platinum group metal element, for example, [Pt (NH ₃ ) ₄ ] ²⁺ or [Pt (NH ₃ ) ₆ ] ⁴⁺ can be expressed. There is an ammine complex cation of platinum that can be produced, or an ammine complex cation of ruthenium that can be represented by [Ru (NH ₃ ) ₄ ] ²⁺ or [Ru (NH ₃ ) ₆ ] ³⁺ .

  In the present invention, two or more kinds of complex cations can be used simultaneously. For example, by using a platinum ammine complex cation and a ruthenium ammine complex cation at the same time, a platinum-ruthenium binary alloy having a CO poisoning resistance can be obtained.

  In the reduction step of reducing a cation containing a platinum group metal element adsorbed on the cation exchange resin of the present invention, it is preferable to reduce the cation using a reducing agent. It is preferable to preferentially reduce cations present in the vicinity of the surface of the carbon particles in the mixture by adjusting the concentration and the pressure, time, and temperature at which the reduction is performed.

  For example, when this step is performed using hydrogen as a reducing agent at a reduction temperature of 180 ° C., cations adsorbed on the cation exchange resin near the carbon particle surface can be selectively reduced. This selective reduction utilizes the fact that the carbon particles have catalytic activity for the reduction reaction of the cation of the platinum group metal element.

  In the reduction step of the present invention, the amount of platinum group metal formed on the surface of the carbon particles in the mixture and the ion cluster of the cation exchange resin is 50 parts by weight with respect to 100 parts by weight of the total platinum group metal. It is preferable to exceed 80, more preferably 80 parts by weight.

  The contact surface between the carbon particle surface and the ion cluster of the cation exchange resin is a place where electrons and protons can be exchanged at the same time. Therefore, the ratio of the amount of platinum group metal supported on the contact surface is increased. Thus, the amount of platinum group metal used for the PEFC electrode can be reduced, and the cost of PEFC can be reduced.

  Reducing agents that can be used in this reduction process include hydrogen, hydrogen sulfide, hydrogen iodide, non-metallic ions such as iodine ions, lower oxides such as carbon monoxide and sulfur dioxide, sodium phosphinate, sodium thiosulfate, hydrogenation Examples include hydrides such as sodium boron and lithium tetrahydroaluminate, hydrazine, diimide, formic acid, aldehyde, and saccharides.

  In particular, a gas containing hydrogen gas or hydrazine is preferable because it is suitable for mass production. The hydrogen gas is preferably used as a mixed gas (hydrogen mixed gas) with an inert gas such as nitrogen, helium or argon, and the hydrogen gas content of the hydrogen mixed gas is 10 vol% or more. Is preferred.

  Further, the reduction temperature in this step is preferably lower than the decomposition temperature of the resin in order to prevent deterioration of the cation exchange resin. For example, when the cation exchange resin is a perfluorocarbon sulfonic acid type cation exchange resin, it is possible to suppress degradation of the resin by reducing it at a temperature lower than the decomposition temperature of 280 ° C.

  When hydrogen gas or a hydrogen mixed gas is used as the reducing agent, the reduction temperature condition is preferably 100 ° C. or higher and 200 ° C. or lower. When the temperature condition is within this range, a mixture in which 80 parts by weight or more of 100 parts by weight of all catalyst metals are supported on the contact surface between the carbon particle surface and the ion cluster of the cation exchange resin is efficiently produced. Can do. This means that the catalytic activity for the cation reduction reaction of the catalytic metal element of the carbon particles is high when the reduction temperature condition is 100 ° C. or higher, and that the cation exchange resin is less deteriorated when it is 200 ° C. or lower. It is due to.

  The mixture containing the carbon particles and the cation exchange resin used in the present invention can be produced by forming a paste of a solution of carbon particles and a cation exchange resin or a dispersion of this resin and then drying the paste. . The solvent contained in the cation exchange resin solution or the resin dispersion is preferably a mixed solution of water and alcohol, and the alcohol preferably has 4 or less carbon atoms. Further, the paste may contain a fluorine-based resin such as PTFE particles or / and a thickener such as carboxymethyl cellulose and glycerin as necessary.

  As a shape of the mixture containing the carbon particles and the cation exchange resin that can be used in the present invention, there are a sheet shape and a powder shape. When the mixture is in sheet form, a catalyst layer is obtained by applying a platinum group metal to the mixture. Therefore, the thickness of the mixture is preferably 3 μm or more and 30 μm or less in order to maintain sufficient strength as the catalyst layer, high electron conductivity, and high gas diffusivity, and is 3 μm or more and 20 μm or less. Is more preferable. On the other hand, when the mixture is in the form of particles, a catalyst layer can be obtained by forming a platinum group metal into the mixture and then forming it into a sheet.

  Therefore, the average particle size of the particulate mixture is preferably 0.10 μm or more and 200 μm or less. The reason for this is as follows. The surface of the catalyst layer produced using a mixture having an average particle size of 200 μm or less is remarkably flat compared to the case where a catalyst layer having a particle size larger than 200 μm is used. Since the current distribution in the electrode surface becomes more uniform as the surface becomes flat, the output performance of the PEFC having a catalyst layer manufactured using a mixture having an average particle size of 200 μm or less is larger than 200 μm. Is significantly higher than.

  A particulate mixture having an average particle size of 0.1 μm or more has a feature such that the scattering property is lower than that of an average particle size smaller than 0.1 μm. Therefore, a mixture having an average particle size of 0.1 μm or more is superior in terms of handling compared to a mixture having an average particle size smaller than 0.1 μm. Furthermore, although the cause is not clear, the output performance of PEFC having a catalyst layer produced using a mixture having an average particle size of 0.1 μm or more is higher than that using an average particle size smaller than 0.1 μm. Remarkably high.

  Examples of a method for controlling the average particle size of the particulate mixture include a method of classifying particles using a sieve or a classifier, and a method of pulverizing or granulating particles using a pulverizer or a granulator. is there. As the classifier, a hydraulic classifier, a mechanical classifier, a wet classifier such as a liquid cyclone, or a pneumatic classifier such as a dry cyclone can be used. As the pulverizer, those of a high-speed rotational impact shear type, a roll rotary type, a ball mill, an airflow pulverization type, and a shear friction type can be used. In particular, when a ball mill is used as a pulverizer, a mixture having a narrow particle size distribution can be easily obtained. Moreover, it can grind | pulverize efficiently by using 2 or more types of grinders. The pulverizer can also be used as a granulator by adjusting the operating conditions. Moreover, when controlling the average particle diameter of a mixture to 10 micrometers or less, wet grinding is preferable.

  Examples of the cation exchange resin that can be used in the present invention include perfluorocarbon sulfonic acid type or styrene-divinylbenzene sulfonic acid type cation exchange resins, and cation exchange resins having carboxyl groups as ion exchange groups. Further, as the carbon particles, carbon black exhibiting high activity with respect to the reduction reaction of a cation containing a platinum group metal element is preferable. For example, carbon black such as Denka Black, Vulcan XC-72, Black Pearl 2000 and the like are particularly preferable. preferable.

[Example 1]
The present invention will be described below with reference to preferred embodiments.

  Nafion was used as the cation exchange resin. The glass transition temperature of Nafion used here was 116 ° C., and the decomposition temperature was 280 ° C.

  A paste was prepared by stirring a cation exchange resin solution (Nafion 5 wt% solution, Aldrich) and carbon particles (Vulcan XC-72, Cabot). The mixing ratio of the cation exchange resin solution and the carbon particles was 11: 1. Next, this paste was applied to carbon paper to a thickness of 100 μm and then dried at room temperature, thereby forming a mixture containing carbon particles and a cation exchange resin on carbon paper. The thickness of this mixture was 25 μm.

  Subsequently, in the heating step, carbon paper having a mixture containing carbon particles and a cation exchange resin formed on the surface was heated at 150 ° C. for 1 hour in a nitrogen atmosphere. This temperature is not lower than the glass transition temperature of the cation exchange resin and not higher than the decomposition temperature.

Further, in the adsorption step, carbon paper having a mixture of carbon particles and cation exchange resin formed on its surface is immersed in an aqueous solution of [Pt (NH ₃ ) ₄ ] Cl ₂ and then washed with deionized water. And drying in air at 60 ° C. In the subsequent reduction step, the PEFC electrode of Example 1 was prepared by allowing a carbon paper having a mixture containing carbon particles and a cation exchange resin on the surface to stand in a hydrogen atmosphere at 200 ° C. for 7 hours. did.

[Example 2]
A PEFC electrode of Example 2 was produced in the same manner as Example 1 except that the heating time in the heating step was 30 minutes.

[Example 3]
A PEFC electrode of Example 3 was produced in the same manner as in Example 1 except that the heating time in the heating step was 2 hours.

[Example 4]
A PEFC electrode of Example 4 was produced in the same manner as in Example 1 except that the heating time in the heating step was 5 hours.

[Example 5]
A PEFC electrode of Example 5 was produced in the same manner as in Example 1 except that the heating temperature in the heating step was 130 ° C.

[Example 6]
A PEFC electrode of Example 6 was produced in the same manner as in Example 1 except that the heating temperature in the heating step was 180 ° C.

[Example 7]
A PEFC electrode of Example 7 was produced in the same manner as in Example 1 except that the heating temperature in the heating step was 250 ° C.

[Comparative Example 1]
A PEFC electrode of Comparative Example 1 was produced in the same manner as in Example 1 except that the heating step was not performed.

[Comparative Example 2]
A PEFC electrode of Comparative Example 2 was produced in the same manner as in Example 1 except that the heating temperature in the heating step was 100 ° C.

[Comparative Example 3]
A PEFC electrode of Comparative Example 3 was produced in the same manner as in Example 1 except that the heating temperature in the heating step was 300 ° C.

  Table 1 shows the contents of the electrodes for PEFC of Examples 1 to 7 and Comparative Examples 1 to 3 manufactured here.

  Next, for the PEFC electrodes of Examples 1 to 7 and Comparative Examples 1 to 3, the amount of platinum supported on the PEFC electrode, the active surface area of the supported platinum, and the active surface area per 1 mg of platinum were determined.

The amount of platinum supported on the PEFC electrode was determined by extracting platinum contained in the PEFC electrode with aqua regia and quantifying the platinum in the extract by ICP emission spectrometry. The active surface area of platinum supported on the electrode for PEFC works by voltammetry using a solid polymer membrane (Nafion 115, DuPont) as the electrolyte, the PEFC electrode as the working electrode, and the same electrode as the working electrode as the counter electrode. The amount of electricity resulting from the elimination reaction of hydrogen at the electrode was determined, and the value obtained by dividing this amount of electricity by 210 (μC / cm ² ) was defined as the active surface area of platinum. Furthermore, the active surface area per 1 mg of platinum in the PEFC electrode was obtained by dividing this active surface area by the amount of platinum supported. The measurement results are shown in Table 2.

  Table 2 shows the following. Since the temperature in the heating step of the PEFC electrode of Comparative Example 3 was 300 ° C., which was higher than the decomposition temperature of Nafion, 280 ° C., Nafion was decomposed and platinum was not supported.

  The total amount of carbon particles and cation exchange resin contained in the PEFC electrode was found to be substantially the same in Examples 1 to 7 and Comparative Examples 1 and 2, but the amount of platinum supported on the PEFC electrode It was found that Examples 1-7 were more in comparison with Comparative Examples 1 and 2. Moreover, it turned out that the active surface area of 1 mg of platinum carry | supported by the electrode for PEFC is larger compared with the comparative examples 1 and 2 of Examples 1-7.

  Moreover, it turned out that the heating time of a heating process hardly influences the platinum carrying amount of the electrode for PEFC, and the active surface area of 1 mg of platinum from the comparison of Examples 1-4. Further, from the comparison between Examples 1 and 5 to 7, when the heating temperature in the heating process is not less than 116 ° C. of Nafion glass transition temperature and not more than 280 ° C., the amount of platinum supported on the PEFC electrode and platinum It was found to have little effect on the active surface area of 1 mg.

  The above results indicate that the area of the contact surface between the carbon surface contained in the PEFC electrodes of Examples 1 to 7 and the ion cluster of the cation exchange resin is larger than that of the PEFC electrodes of Comparative Examples 1 and 2. Means. Therefore, a heating process in which a mixture containing carbon particles and a cation exchange resin is heated at a temperature not lower than the glass transition temperature of the cation exchange resin and not higher than the decomposition temperature reduces the contact surface between the carbon particles and the cation exchange resin. It became clear that there was an effect to suppress.

  In addition, the active surface area per 1 mg of platinum was larger in the PEFC electrodes of Examples 1 to 7 than in Examples 1 and 2, and this is the same as in the PEFC electrodes of Examples 1 to 7. This means that the utilization rate of platinum is higher than that of the PEFC electrodes of Comparative Examples 1 and 2. Therefore, the process of heating the mixture containing the carbon particles and the cation exchange resin at a temperature not lower than the glass transition temperature of the cation exchange resin and not higher than the decomposition temperature is a phenomenon in which the skeleton of the cation exchange resin covers platinum. It became clear that there was an inhibitory effect.

[Example 8]
In the reduction step, the carbon paper in which a mixture containing carbon particles and a cation exchange resin was formed was allowed to stand in a mixed gas atmosphere of 150 ° C. hydrogen and argon in a volume ratio of 3: 7 for 7 hours. In the same manner as in Example 1, the PEFC electrode of Example 8 was produced.

[Example 9]
A PEFC electrode of Example 9 was produced in the same manner as in Example 8 except that a gas mixture of hydrogen and helium at 150 ° C. in a volume ratio of 3: 7 was used in the reduction step.

[Example 10]
A PEFC electrode of Example 10 was produced in the same manner as in Example 8 except that hydrazine at 25 ° C. was used in the reduction step.

[Example 11]
A PEFC electrode of Example 11 was produced in the same manner as in Example 8, except that hydrogen sulfide at 25 ° C. was used in the reduction step.

[Example 12]
A PEFC electrode of Example 12 was produced in the same manner as in Example 8, except that a gas mixture of 150 ° C. hydrazine and argon in a volume ratio of 3: 7 was used.

[Example 13]
A PEFC electrode of Example 13 was produced in the same manner as in Example 8, except that in the reduction step, a mixed gas of hydrogen sulfide and argon having a volume ratio of 3: 7 at 25 ° C. was used.

  Table 3 shows the contents of the electrodes for PEFC of Examples 8 to 13 produced here.

For the PEFC electrodes of Examples 8 to 13, in the same manner as in Example 1, the total amount of carbon particles and cation exchange resin, the amount of platinum supported on the PEFC electrode, the active surface area of the supported platinum, per 1 mg of platinum The active surface area was determined. The results are shown in Table 4.

  From the results of Tables 3 and 4, it was found that the type of reducing gas in the reducing step hardly affects the amount of platinum supported on the PEFC electrode and the active surface area per 1 mg of platinum.

[Example 14]
The same procedure as in Example 1 was used except that an aqueous solution of [Pt (NH ₃ ) ₆ ] Cl ₄ was used as an aqueous solution for immersing the carbon paper formed with a mixture containing carbon particles and a cation exchange resin in the adsorption step. Thus, an electrode for PEFC of Example 14 was produced.

[Example 15]
The same procedure as in Example 1 was used except that an aqueous solution of [Ru (NH ₃ ) ₄ ] Cl ₂ was used as an aqueous solution for immersing the carbon paper formed with a mixture containing carbon particles and a cation exchange resin in the adsorption step. Thus, an electrode for PEFC of Example 15 was produced.

[Example 16]
The same procedure as in Example 1 was used except that an aqueous solution of [Ru (NH ₃ ) ₆ ] Cl ₃ was used as an aqueous solution for immersing the carbon paper formed with a mixture containing carbon particles and a cation exchange resin in the adsorption step. Thus, an electrode for PEFC of Example 16 was produced.

[Example 17]
In the adsorption process, [Pt (NH ₃ ) ₄ ] Cl ₂ and [Ru (NH ₃ ) ₄ ] Cl ₂ are used as an aqueous solution in which a carbon paper formed with a mixture containing carbon particles and a cation exchange resin is immersed. A PEFC electrode of Example 17 was produced in the same manner as in Example 1 except that an aqueous solution containing a molar ratio of 1: 1 was used.

  The contents of the PEFC electrodes of Examples 14 to 17 produced here are shown in Table 5.

The characteristics of the PEFC electrodes of Examples 14 to 17 as the anode were investigated. The survey method is as follows. First, PEFCs each having these PEFC electrodes as anodes were manufactured. The same electrode as the working electrode was used for the cathodes of all PEFCs, and a solid polymer membrane was used for the electrolyte. Next, while supplying hydrogen gas or hydrogen gas containing carbon monoxide to the anode and supplying oxygen to the cathode, the PEFC was operated at a cell temperature of 80 ° C. and a current density of 100 mA / cm ² , and the potential of the anode at that time was measured. did. The results are shown in Table 6. As a comparison, the results of the PEFC electrode of Example 1 are also shown.

From the results of Table 5 and Table 6, it can be seen that the characteristics of the PEFC electrode of Example 14 as the anode are substantially the same as those of the PEFC electrode of Example 1. From this, the PEFC electrode obtained using [Pt (NH ₃ ) ₆ ] Cl ₄ in the adsorption step is the same as the PEFC electrode obtained using [Pt (NH ₃ ) ₄ ] Cl _2. I found out.

  Also, from the results of Tables 5 and 6, the characteristics of the PEFC electrodes of Examples 15 and 16 as anodes are slightly inferior to those of the PEFC electrode of Example 1, but when hydrogen gas is supplied. It can be seen that the potential is extremely low. This means that ruthenium is supported on these electrodes and that these electrodes have sufficient performance as PEFC anodes.

Further, from the results of Table 5 and Table 6, it is understood that the potential when hydrogen gas containing carbon monoxide is supplied to the PEFC electrode of Example 17 is lower than that of the PEFC electrode of Example 1. . From this, the platinum-ruthenium binary having excellent CO poisoning resistance can be obtained by using an aqueous solution containing [Pt (NH ₃ ) ₄ ] Cl ₂ and [Ru (NH ₃ ) ₄ ] Cl ₂ in the adsorption step. It turned out that the electrode for PEFC provided with the alloy was obtained.

Claims (1)

After heating the mixture containing the carbon particles and the cation exchange resin at a temperature not lower than the glass transition temperature and not higher than the decomposition temperature of the cation exchange resin, platinum group metal is added to the cation exchange resin included in the mixture. A method for producing an electrode for a polymer electrolyte fuel cell, comprising a step of adsorbing a cation containing an element and then reducing the cation.