JP5155792B2 - Platinum catalyst and method for producing the same - Google Patents

Description

  The present invention relates to a platinum catalyst suitable for fuel cell applications and the like and a method for producing the same.

  Platinum is widely used as a catalyst material for fuel cells and exhaust gas purification devices. When platinum is used as a catalyst material, it is desired to increase the catalytic activity by increasing the surface area that can contact the target gas as much as possible. By using a catalyst having high activity, it is possible to improve the performance of the apparatus or reduce the required amount of catalyst to reduce the production cost. For this reason, nano particles with a particle size reduced to the nanometer order are particularly suitable for catalyst applications.

In general, platinum nanoparticles are produced by reducing a platinum salt such as chloroplatinic acid (H ₂ PtCl ₆ ) in an aqueous solution (see, for example, Non-Patent Document 1). As the reducing agent, sodium dithionite, sodium borohydride, sodium citrate, methanol, ethanol, formaldehyde and the like are used.

  In addition, when producing platinum nanoparticles such as those described above, by controlling the particle size using a surfactant containing long-chain carbon, platinum nanoparticles are generated on the surface of the carbon particles, and the activity and durability are improved. It has been proposed to obtain a high Pt / C catalyst (see, for example, Non-Patent Document 2).

  In addition, it has been proposed to suppress the aggregation by using a polymer compound such as polyvinyl pyrrolidone (PVP) and reduce the particle diameter to produce highly dispersible platinum nanoparticles on carbon particles (for example, , See Non-Patent Document 3.)

JP 2008-027775 A A. Guha et al., "Surface-modified carbons as platinum catalyst support for PEM fuel cells", Carbon, March 2007, 45, 7, p.1506-1517 X. Yu, S. Ye, "Recent advances in activity and durability enhancement of Pt / C catalytic cathode in PEMFC", Journal of POWER Sources, July 2007, Vol.172, No.1, p.133-144 Chen and Xing, "Polymer-Mediated Synthesis of Highly Dispersed Pt Nanoparticles on Carbon Black", Langmuir, August 31, 2005, 21, 20, p.9334-9338

  By the way, for the spread of fuel cells in the future, how much the initial cost can be reduced is an important issue. Therefore, cost reduction is required for all materials and manufacturing processes, and it is desired to reduce the processing temperature in each process as much as possible, for example, to about room temperature.

  However, in the conventional method for producing platinum nanoparticles as described above, the reduction treatment, the reducing agent removal treatment, and the like are performed at a relatively high temperature. For example, in the method described in Non-Patent Document 1, in order to obtain platinum fine particles having a small particle size, the reduction treatment of the platinum complex precursor is performed in a temperature range of 75 to 85 (° C.) like sodium dithionite. It has been shown to be performed using a mild mild reducing agent and further using ethylene glycol at 140 ° C. Further, in the method of controlling the particle size of the platinum nanoparticle using a surfactant or a polymer compound as described in Patent Documents 2 and 3, for example, 400 nm is used for removing the surfactant or the polymer compound. High-temperature treatment at (° C) or higher is required. Therefore, even if any of these methods is applied, it is difficult to synthesize platinum catalysts at room temperature.

  The present invention has been made against the background of the above circumstances, and an object thereof is to provide a highly active platinum catalyst capable of low-temperature synthesis and a method for producing the same.

In order to achieve such an object, the gist of the first invention is a method for producing a platinum catalyst in which platinum fine particles are supported on a fine carbon base material, comprising (a) a platinum salt and camphor . A dispersion step of dispersing in a solvent containing an organic solvent, (b) a carbon mixing step of mixing the carbon substrate with the dispersion obtained in the dispersion step, and (c) sodium borohydride in the carbon substrate. Is added to the carbon mixture mixed in the dispersion to reduce the platinum salt to produce platinum fine particles on the surface of the carbon substrate in the carbon mixed solution, and (d) the platinum fine particles Separating the platinum catalyst in which the platinum fine particles are supported on the surface of the platinum fine particles and the camphor is attached to the surfaces of the platinum fine particles by filtering the generated carbon mixed liquid. It is in.

Moreover, the place made into the summary of the platinum catalyst for oxygen reduction electrodes of the fuel cell of 2nd invention for achieving the said objective is manufactured by the manufacturing method of any one of Claims 1 thru | or 3. Is characterized by .

According to the first invention, in the dispersion step, camphor is dispersed in a solvent containing an organic solvent together with a platinum salt, and in the carbon mixing step, when the carbon substrate is mixed in the dispersion, in the reduction step, The platinum salt is reduced by the reducing action of the sodium borohydride, etc., and platinum fine particles with camphor attached thereto are generated on the surface of the carbon substrate, and further, in the separation step, the generated platinum catalyst is separated from the carbon mixture. And then taken out. At this time, camphor , together with an organic solvent, suitably functions as a dispersing agent for dispersing platinum fine particles, so that it is sufficiently low in temperature, for example, about room temperature, and does not cause aggregation or the like, for example, fine and particle size distribution on the order of nanometers. Narrow platinum fine particles are generated on the surface of the carbon substrate. Further, since the platinum catalyst is separated by filtering the carbon mixture , this separation step can also be performed at a low temperature of about room temperature. Therefore, a highly active platinum catalyst can be obtained at a lower temperature than in the past.

In the above production process, the solvent is separated in the separation process, but the camphor remains attached to the surface of the platinum fine particles even after the separation process. However, when using a platinum catalyst, heating at a temperature of less than 100 (° C) under normal pressure sublimates the camphor and disappears, and a highly active platinum catalyst is obtained. Rather, it can be removed at low temperatures, so the entire process including this removal can be performed at low temperatures. In addition, the platinum catalyst of the first invention before the disappearance of camphor is low in reactivity with solvents such as ethanol and methanol and does not ignite even when mixed with a solvent, so it is safer than commercially available catalysts. There are also advantages. Such an action is considered to be due to the presence of camphor on the surface of the platinum fine particles.

According to the second aspect of the invention, the platinum catalyst is highly active because platinum fine particles are attached to the surface of the carbon base material and camphor is attached to the surface of the platinum fine particles. 1 It is possible to synthesize at a low temperature using the production method of the invention.

In the first and second inventions, camphor is essential. As a material that can be easily removed at a low temperature, a highly volatile solvent can be considered. However, when such a solvent is used, it is volatilized during the dispersion process or during storage, so that dispersibility and storability cannot be obtained. . Moreover, it is essential to mix a carbon base material after mixing camphor and platinum salt. Thus, the dispersibility of platinum is improved by mixing camphor and platinum salt prior to mixing the carbon base material. If the carbon base material is mixed before the platinum and camphor are combined, the carbon base material and the camphor are combined, so that it is difficult to obtain a platinum dispersion effect. Incidentally, the camphor is including synthetic camphor.

Moreover, since camphor can be easily removed when using a platinum catalyst as described above, there is no particular inconvenience even if it is used in a large amount. That is, it is sufficient that an amount sufficient to reduce the total amount of the platinum salt is used, and an excessive amount may be used. However, the amount of camphor is preferably kept at 30: 1 or less in molar ratio with respect to the amount of platinum.

In addition, the said patent document 1 manufactures the membrane electrode assembly for fuel cells using camphor which is 1 type of a sublimable organic material. However, in this technique, in the manufacturing process of a membrane electrode assembly in which a catalyst layer, an electrolyte layer, and a catalyst layer are sequentially formed, the catalyst solution is applied to the surface of the catalyst layer having a large number of pores. For the purpose of suppressing the penetration of the electrolyte into the layer, a substance that easily disappears is filled in the many pores. That is, although the sublimable organic material is applied to the technology related to the catalyst, it is not related to the present invention using camphor when synthesizing the platinum catalyst.

  Moreover, although the said fine carbon base material is carbon microparticles, for example, a shape is not specifically limited. For example, carbon nanotubes, carbon nanohorns, and carbon nanofibers are also included in the carbon substrate of the present application. In addition, the order of a carbon mixing process and a reduction process is not specifically limited. The carbon mixing step may be performed before, during, or after the reduction step, and may be continued in these multiple steps.

Here, in the method for producing a platinum catalyst according to the first aspect of the present invention, preferably, in the carbon mixing step, the carbon base material is dispersed in a solvent and mixed with the dispersion. If it does in this way, it will mix with the dispersion liquid which disperse | distributed platinum salt and camphor in the solvent in the state which disperse | distributed the carbon base material which has hydrophobicity in the solvent. Therefore, even when the dispersion medium of the dispersion is water, there is an advantage that the carbon base material can be suitably dispersed in the dispersion.

  Preferably, in the method for producing a platinum catalyst according to the first invention, the dispersion step, the carbon mixing step, the reduction step, and the separation step are performed at room temperature. If it does in this way, since all the processes for manufacturing a platinum catalyst are implemented at normal temperature, manufacturing cost can be reduced further.

Preferably, in the method for producing a platinum catalyst of the first invention, sodium borohydride for reducing the platinum salt is added to the organic solvent in the reduction step. Thus, since sodium borohydride is added in addition to the camphor and the organic solvent, the platinum salt in the organic solvent is more easily reduced to obtain a platinum catalyst . Also, sodium borohydride, be added at the start-stage reduction process, be added during the progress, or may be added at the end.

  Although the platinum salt is not particularly limited, for example, chloroplatinic acid solution, platinum (IV) chloride, platinum (II) hexafluoroacetylacetonato complex, platinum (II) acetylacetonato complex, platinum (II) bromide Platinum (II) iodide, platinum (IV) sulfide, potassium tetrachloroplatinate (II), ammonium tetrachloroplatinate (II), sodium hexachloroplatinate (IV) hexahydrate, and the like. Not limited to these, more complex salts can be used. The platinum salt can be produced, for example, by dissolving a platinum ingot with an appropriate acid such as aqua regia. Moreover, although this invention is applied to a platinum catalyst and its manufacturing method, it can be applied also to the fine particles of silver, gold | metal | money, nickel, copper, and those manufacturing methods. These applications include metal film formation on flexible substrates, catalysts, sensors, electrical contacts, other electronic or optoelectronic applications, medical and biomedical applications, and the like.

  The organic solvent is not particularly limited, and is based on vegetable oil-based solvents such as terpineol and rosemary oil, paraffin hydrocarbons such as hexane, ketones such as acetone, ethylene glycol, diethylene glycol monobutyl ether, ethylene glycol monobutyl ether, propylene glycol mono Examples include glycol solvents such as butyl ether and propylene glycol dibutyl ether.

Preferably, in the dispersion step, the platinum salt aqueous solution is added to a mixture of the camphor and the organic solvent. That is, it is preferable that an appropriate amount of water is mixed in the dispersion step. However, the mixing of water is preferably performed simultaneously by preparing an aqueous solution of a platinum salt in advance and dispersing it in an organic solvent. If it does in this way, it will become easy to suppress aggregation of platinum salt and to disperse suitably in an organic solvent. The aqueous solution of the platinum salt is prepared to have an appropriate liquidity, for example, acidic, and this can be easily obtained by mixing water when dissolving the ingot with an acid as described above, for example.

Further, since the sodium borohydride is water-soluble, the sodium borohydride is removed together with the solvent and water when the platinum catalyst is recovered by filtering the carbon mixed liquid in which the platinum fine particles are generated in the separation step. The Therefore, it is suppressed that an impurity mixes in a platinum catalyst.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a process diagram for explaining a method for producing a platinum catalyst according to an embodiment of the present invention. In FIG. 1, first, an appropriate solvent such as acetone is prepared (step 1), and camphor (1,7,7-trimethylbicyclo [2.2.1] heptan-2-one, whose structural formula is shown in FIG. 2; C ₁₀ H ₁₆ O) is mixed (step 2) and this is stirred in stirring step 3. The mixing ratio is appropriately determined. For example, 250 (g) of acetone is added to 8.42 (g) of camphor. The stirring time is about 1 minute, for example, and the stirring speed is about 300 rpm, for example. The camphor is, for example, a synthetic camphor having a purity of 99.9 (%) and has a characteristic that it easily sublimes even at room temperature. In this embodiment, camphor is used as a sublimable organic material.

Next, distilled water is prepared (step 4). On the other hand, in the platinum salt dissolution step 5, an appropriate amount of distilled water, for example, a platinum salt such as chloroplatinic acid (H ₂ PtCl ₆ ) is distilled in a suitable container having acid resistance. For example, a platinum salt solution (hereinafter referred to as “10% H ₂ PtCl ₆ ”) containing water at a concentration of about 10 (wt%) is prepared by adding water. This platinum salt solution is mixed with the distilled water and stirred in the stirring step 6. This stirring time may be about 1 minute, for example. In this step, for example, 732 (g) of distilled water is added to 8.09 (g) of a platinum salt solution.

  Next, in the stirring step 7, the above two solutions are mixed and stirred using an appropriate stirring device for 3 hours or more, for example, about 21.5 hours. Thereby, platinum salt is disperse | distributed in a solvent and reduction | restoration of platinum salt advances slowly by the reduction effect | action of camphor. Therefore, this process corresponds to a dispersion process and a reduction process.

  Next, an appropriate solvent such as acetone is prepared (step 8), fine carbon is added thereto (step 9), and the mixture is mixed with an ultrasonic mixer in the ultrasonic mixing step 10. The mixing time is, for example, about 5 to 10 minutes. The solvent is, for example, a mixture of 12 (g) acetone and 8 (g) water, and 0.15 (g) fine carbon is added to this. In the stirring step 11, this is mixed with the above dispersion and subjected to a stirring process. The stirring time is, for example, about 30 minutes to 10 hours, for example, 4 hours. In this embodiment, the stirring step 11 corresponds to a carbon mixing step.

Next, in the reducing agent addition step 12, sodium borohydride (NaBH ₄ ) is added to the above mixture, and in the reduction / precipitation step 13, the mixture is further stirred. Sodium borohydride is added, for example, by dropping, and the stirring time after dropping is, for example, about 4 hours. As a result, the platinum salt is reduced to produce nanometer-order platinum fine particles on the fine carbon surface, and a Pt / C fine particle dispersion is obtained. Next, when the stirring is stopped and the mixture is allowed to stand, the produced Pt / C fine particles are precipitated and separated into a solvent layer and an aqueous layer containing the Pt / C fine particles (step 14). The standing time is, for example, overnight. The above sodium borohydride also has a platinum salt reducing action, and the addition is completed to complete the reduction. That is, sodium borohydride supplements the reducing action of a solution of camphor dissolved in acetone. In the reducing agent addition step 12 described above, another reducing agent may be added instead of sodium borohydride. The above steps are all performed at room temperature, that is, about 25 (° C.). In the present embodiment, in addition to the stirring step 7, the reduction / precipitation step 13 also corresponds to the reduction step.

  Next, in the separation / drying step 15, water is removed from the platinum dispersion separated into two layers as described above, and a drying treatment is further performed at room temperature. Separation of water may be performed using, for example, a well-known separatory funnel, etc.When the collected solvent layer is dried to remove the solvent, Pt / C catalyst powder (platinum-supported carbon catalyst) is obtained. It is done. This separation / drying step 15 corresponds to the separation step. The separation / drying step 15 can be carried out immediately without waiting for the treatment to stand in the step 14, but water can be easily removed by allowing it to stand and separate into two layers. There is an advantage that the filtration time can be shortened.

  According to this example, when camphor sublimated at room temperature is dispersed in an organic solvent together with chloroplatinic acid, the reduction of the chloroplatinic acid starts. Platinum fine particles adhering to the surface are produced on the fine carbon surface. Therefore, when the solvent and water are separated and subjected to a drying process in the separation / drying step, a Pt / C catalyst powder in which platinum fine particles with camphor attached to the surface are present on the finely divided carbon surface is obtained. Since all the above steps are performed at room temperature, a highly active platinum catalyst can be obtained at a lower temperature than in the past. In addition, the catalyst powder obtained in this way is less reactive and does not ignite even when mixed with a solvent until the camphor is removed by drying treatment, so it is safer than commercial catalysts. There is also an advantage in that.

  In addition, according to this example, sodium borohydride is further added as a reducing agent, so that the reduction of chloroplatinic acid can be completed in a relatively short time at room temperature.

Hereinafter, a more specific example in the case of producing the Pt / C catalyst powder according to FIG. 1 will be described. Each manufacturing method of samples 1-4 is as follows.
Sample 1: 0.97 (g) camphor was mixed with 21.5 (g) acetone, and 0.6 (g) 10% H ₂ PtCl ₆ dissolved in 72 (g) water was added thereto. This solution 0.6 (g) contains 0.06 (g) platinum. The mixture was stirred at room temperature for 23 hours, 50 (mg) of fine carbon was added thereto, and the mixture was stirred for 30 minutes. To this, 0.5M (1M NaBH ₄ ) was added and stirred for 3 hours. The produced Pt / C particles were then separated by filtration.

Sample 2: 9.52 (g) camphor was mixed with 197.5 (g) acetone and stirred at a rotational speed of 300 rpm. To this was added 6.13 (g) of 10% H ₂ PtCl ₆ dissolved in 707 (g) of water. The mixture was stirred at room temperature for 16 hours, 0.49 (g) of finely divided carbon was added thereto, and the mixture was stirred for 3 hours. To this, 5M (1 ml) of 1M NaBH ₄ was added and stirred for 3 hours. The produced Pt / C particles were then separated by filtration. Since the amount of camphor added in Sample 2 is larger than that in Sample 1, reduction can be performed in a shorter stirring time. The amount of NaBH ₄ higher than that of sample 1 corresponds to the increased amount of camphor added. Thus, the stirring time and the amount of NaBH ₄ added may be determined as appropriate according to the amount of camphor.

Sample 3: 16.5 (g) camphor was mixed with 551.84 (g) acetone and stirred at a rotational speed of 300 rpm. To this was added 15.47 (g) of 10% H ₂ PtCl ₆ dissolved in 1415 (g) of water. The mixture was stirred at room temperature for 16 hours, 0.59 (g) of finely divided carbon was added thereto, and the mixture was stirred for 6.5 hours. To this was added 25 (ml) of 1M NaBH ₄ and stirred for 7 hours. The produced Pt / C particles were then separated by filtration.

Sample 4: 8.42 (g) camphor was mixed with 252 (g) acetone and stirred at a rotational speed of 300 rpm. To this was added 8.09 (g) of 10% H ₂ PtCl ₆ dissolved in 732.5 (g) of water. The mixture was stirred at room temperature for 21.5 hours, 0.15 (g) of finely divided carbon was added thereto, and the mixture was stirred for 4 hours. To this, 13 (ml) of 1M NaBH ₄ was added and stirred for 4 hours. The produced Pt / C particles were then separated by filtration.

  Each sample produced as described above was dispersed in a solvent and subjected to oxygen reduction current density, XRD measurement, TGA measurement and the like. An appropriate solvent may be used depending on the dispersibility of the sample. For example, sample 1 was dispersed in acetone and sample 2 was dispersed in an acetone / ethanol / water mixture. The current density was measured by rotating electrode cyclic voltammetry using the dispersion. Moreover, XRD produced the thin film by dripping a dispersion liquid on a slide glass and drying at room temperature, and made it the measurement sample.

The formulation specifications and evaluation results are shown in Table 1 together with the evaluation results of other Examples NC-1 to NC-5 and commercial products 1 and 2. The commercial products 1 and 2 are generally used as catalysts for fuel cells, but the amounts of platinum are different from each other. In Table 1, 1-4 correspond to the samples 1-4 described above. In the “Camphor” column, the amount of the substance calculated with a molecular weight of 152 was written instead of the above-mentioned mixing amount. The “NaBH ₄ / Pt” column is the molar ratio of the mixed NaBH ₄ and Pt. The “carbon surface area” column is the surface area (SA) per mass of the finely divided carbon used, and only NC-4 and NC-5 have SA of 950 (m ² / g). m ² / g) was used. “Temperature” column is the treatment temperature at the time of catalyst synthesis, and all are 25 (° C.).

  Below the horizontal line at the center of Table 1, the characteristics of the Pt / C catalyst to be evaluated are shown. The "Platinum amount" column shows the proportion of the platinum amount contained in each sample, and is the platinum content obtained from the TGA measurement. In the TGA measurement of the Pt / C catalyst, all the carbon and organic components are burned out and only Pt remains, so the proportion of the remaining mass should be equal to the platinum content.

Further, in the “platinum size” column, the platinum size obtained from the measurement results of TEM (transmission electron microscope) and XRD is shown. The TEM was analyzed by dispersing the Pt / C catalyst in a solvent such as hexane and covering the dispersion with a carbon film. Although the TEM measurement is limited to some samples, it is in good agreement with the value calculated from the XRD measurement result (half width of (111) peak). The “active surface area” is a platinum surface area that can function effectively as a catalyst, and was calculated by the following equation (1) from an IV curve measured by rotating electrode cyclic voltammetry. In the following equation (1), Q is the integral area of the IV curve (ie, hydrogen adsorption charge, unit: μC), “210” is the charge amount per unit active surface area of platinum (unit: μC / cm ² ), and W is Platinum weight (unit: g). The numerical value in the “Platinum utilization rate” column is a value obtained by dividing the active surface area by the surface area per unit area calculated from the particle size of platinum, and represents the proportion of all platinum that functions effectively. . Only the exposed part of the platinum surface can contribute to the reaction, and the more the part that is covered with other objects such as the part that is in contact with carbon and the part where platinum is overlapped with each other, the more this value is Get smaller. The “current density” column is an oxygen reduction current density measured at 0.36 (V) and was obtained from the IV curve.
Active surface area = Q / 210W (1)

  As shown in the above measurement results, in any of Samples 1 to 4 and NC-1 to NC-5, a fine platinum powder of 2.5 to 4 (nm) could be reduced and produced by a treatment process only at room temperature. Moreover, the platinum content of the Pt / C catalyst particles was different depending on the production conditions, and a result of 16.5 to 75 (wt%) was obtained in the evaluated range. The TGA measurement results of Samples 1 to 4 are shown in FIGS. In either case, a large weight loss was observed, but in Samples 1 and 2, a residual mass of about 20 (wt%), that is, a platinum content of about 40 (wt%) was obtained.

  FIG. 6 shows XRD analysis results of Samples 1 to 4 and commercial products 1 and 2. The peaks (111), (200), (220), and (311) appearing in FIG. 6 are all obtained in the case of a crystal having a face-centered cubic structure. FIG. 7 shows an enlarged view of the vicinity of the (111) peak in the XRD result. According to these analysis results, it can be seen that the platinum nanoparticles constituting the Pt / C catalyst are all crystallized. That is, a difference in peak height and a slight shift in the peak position are recognized, but Samples 1 to 4 contain Pt having high crystallinity as in the case of a commercially available product.

  FIG. 8 shows the result of measuring the current density of Sample 1 by rotating electrode cyclic voltammetry, that is, the IV curve. The open circuit voltage is about 0.65 (V) and the short circuit current is about 0.19 (A). As shown in Table 1, according to Examples 1 and 2, the current density is about 2 to 3 times that of the commercial product. can get. In addition, in Samples NC-3 to NC-5, the current density equivalent to that of the commercial products 1 and 2 is obtained, and it can be seen that the same characteristics as those of the commercial products processed at high temperature by low temperature synthesis can be obtained. In addition, when NC-5 with a large amount of platinum and the commercial product 2 are compared in terms of activity per unit catalyst, NC-5 is 0.27, commercial product 2 is 0.258, and NC-5 is superior. It was. That is, even when the amount of platinum is large, the Pt / C catalysts of the examples are superior to the commercially available products as compared with those having the same amount of platinum.

  As mentioned above, although this invention was demonstrated in detail with reference to drawings, this invention can be implemented also in another aspect, A various change can be added in the range which does not deviate from the main point.

It is process drawing explaining an example of the manufacturing method of the platinum catalyst of this invention. It is a figure which shows the structural formula of camphor of an example of the sublimable organic material used in the manufacturing process of FIG. It is a TGA measurement result of samples 1 and 2. It is a TGA measurement result of sample 3. It is a TGA measurement result of sample 4. It is a XRD chart of samples 1 to 4 and commercial products 1 and 2. It is a figure which is a part of XRD chart of FIG. 6, and shows the part corresponded to the (111) peak of platinum. It is IV curve of the sample 1 measured by the rotating electrode cyclic voltammetry.

Claims (4)

A method for producing a platinum catalyst in which platinum fine particles are supported on a fine carbon substrate,
A dispersion step of dispersing a platinum salt and camphor in a solvent containing an organic solvent;
A carbon mixing step of mixing the carbon substrate with the dispersion obtained in the dispersion step;
A reduction step of reducing the platinum salt by adding sodium borohydride to a carbon mixed liquid in which the carbon base material is mixed with the dispersion to generate platinum fine particles on the surface of the carbon base material in the carbon mixed liquid. When,
A separation step of filtering the carbon mixed liquid in which the platinum fine particles are generated and separating the platinum catalyst in which the platinum fine particles are supported on the surface of the carbon base material and the camphor is attached to the surface of the platinum fine particles; A process for producing a platinum catalyst, comprising:   The method for producing a platinum catalyst according to claim 1, wherein in the carbon mixing step, the carbon base material is dispersed in a solvent and mixed with the dispersion.   The method for producing a platinum catalyst according to claim 1 or 2, wherein the dispersion step, the carbon mixing step, the reduction step, and the separation step are performed at room temperature. A platinum catalyst for an oxygen reduction electrode of a fuel cell, produced by the production method according to any one of claims 1 to 3 .

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