JP4802484B2 - Catalyst-supported mixed conductor - Google Patents

Description

  The present invention relates to a catalyst-supported mixed conductor.

Conventionally, as shown in FIG. 18, for example, a membrane electrode assembly (MEA) 90 of a fuel cell system is known. The membrane electrode assembly 90 is Nafion (registered trademark, Nafion (Dupon t Corporation)) cathode and an electrolyte membrane 91 made of such a solid polymer membrane, this is bonded to one surface of the electrolyte membrane 91 is air supplied It has an electrode 93 and an anode electrode 92 joined to the other surface of the electrolyte membrane 91 and supplied with a fuel such as hydrogen.

  The cathode electrode 93 is formed of a gas permeable base material such as carbon cloth, carbon paper, or carbon felt, and a cathode catalyst layer formed on the base material on the side of the electrolyte membrane 91 and carrying a catalyst such as platinum (Pt). 93a. A portion of the cathode electrode 93 other than the cathode catalyst layer 93a is formed of a base material, which is a cathode diffusion layer 93b that diffuses air to the cathode catalyst layer 93a on the non-electrolyte side.

  The anode 92 also includes the base material and an anode catalyst layer 92a that is formed on the base material on the side of the electrolyte membrane 91 and carries a catalyst. The portion other than the anode catalyst layer 92a in the anode electrode 92 is also formed of a base material, and this is an anode diffusion layer 92b that diffuses air to the anode catalyst layer 92a on the non-electrolyte side.

  The membrane electrode assembly 90 is sandwiched between unillustrated separators to form a fuel cell as a minimum power generation unit, and a large number of these cells are stacked to form a fuel cell stack. Air is supplied to the cathode catalyst layer 93a by air supply means, and fuel is supplied to the anode catalyst layer 92a by fuel supply means or the like. Thus, the fuel cell system is configured.

In the membrane electrode assembly 90, hydrogen ions (H ⁺ ; protons) and electrons are generated from the fuel by an electrochemical reaction in the anode catalyst layer 92a. Protons move in the electrolyte membrane 91 toward the cathode catalyst layer 93a in the form of H ₃ O ⁺ accompanied by water molecules. The electrons flow through the load connected to the fuel cell system and flow into the cathode catalyst layer 93a. On the other hand, in the cathode catalyst layer 93a, water is generated from oxygen, protons and electrons contained in the air. The fuel cell system can continuously generate an electromotive force by continuously performing such an electrochemical reaction.

  Further, the anode catalyst layer 92a needs to have both electron conductivity, which is a property of conducting electrons, and ion conductivity, which is a property of conducting ions, in order to improve transmission loss of electrons and protons. The cathode catalyst layer 93a also needs to have both electron conductivity and ion conductivity in order to improve transmission loss of electrons and oxygen ions. Therefore, in a general fuel cell system, as shown in FIG. 19, an infinite number of catalyst-supporting carbons 83 formed by supporting a catalyst 82 on a substantially spherical carbon powder 81 and each catalyst-supporting carbon 83 are coupled to each other and illustrated. A polyelectrolyte 84 that binds to a substrate that does not. As the polymer electrolyte 84, the same one as the electrolyte membrane 91 can be used.

  However, it is difficult to completely uniformly mix the carbon powder 81 that is an electron conductor capable of conducting electrons and the polymer electrolyte 84 that is an ion conductor capable of conducting ions. Therefore, in the fuel cell system, electrons and protons or electrons and oxygen ions cannot be evenly transmitted to all the catalysts 82, and some of the catalysts 82 are wasted. It will occur.

  Therefore, mixed conductive carriers having both electron conductivity and ion conductivity have been proposed (for example, Patent Documents 1 to 8). Patent Documents 1 to 4 disclose organic mixed conductive carriers. Patent Documents 5 to 8 disclose inorganic mixed conductive carriers. FIG. 20 shows a catalyst-supporting mixed conductor 86 using these mixed conductive carriers 85. These mixed conductive carriers 85 have both electron conductivity and ionic conductivity. In the conventional catalyst-supported mixed conductor 86 in which the catalyst 82 is supported on the mixed conductive carrier 85, electrons and protons or electrons and Since oxygen ions are suitably transmitted and electrons and protons or electrons and oxygen ions can be transmitted almost uniformly to all the catalysts 82, it is considered that high reaction efficiency can be realized without wasting the catalyst 82. It is done.

JP 2001-202971 A JP 2001-110428 A JP 2003-68321 A Special Table 2002-536787 JP-A-10-255832 JP-A-11-335165 JP 2000-251533 A JP 2000-188117 A

By the way, in the fuel cell system, for example, protons generated in the anode catalyst layer 92a of the membrane electrode assembly 90 move in the electrolyte membrane 91 toward the cathode catalyst layer 93a with water molecules. On the anode catalyst layer 92a side of the 92a and the electrolyte membrane 91, the moisture content tends to decrease and the powder tends to dry, proton transfer is hindered, and the output of the fuel cell system tends to decrease. Further, in the cathode catalyst layer 93a, water is excessive due to the water that has moved with the protons and the generated water generated by the electrochemical reaction, thereby inhibiting the diffusion of air (hereinafter referred to as “flooding”). However, the output of the fuel cell system tends to decrease.

  For this reason, the problem of drying of the anode catalyst layer 92a and the electrolyte membrane 91 can be solved by humidifying hydrogen with a humidifier. However, in the cathode catalyst layer 93a, water generated by the cell reaction and the anode 92 to the cathode 93 Flooding is likely to occur due to the water accompanying the movement of protons, and the output may be reduced.

  The above problems are not unique to the fuel cell system, but occur in all electrochemical devices such as sensors that require conduction of electrons and ions.

  The present invention has been made in view of the above-described conventional situation, and it is a problem to be solved to realize an electrochemical device capable of exhibiting high reaction efficiency and output while realizing prevention of flooding. It is said.

The catalyst-carrying mixed conductor of the present invention includes an electron conductor that can conduct electrons, an ion conductor that is integral with the electron conductor and capable of conducting ions , and a mixed conduction carrier. A catalyst-supported mixed conductor including a magnetic body that is a magnetic catalyst that is supported and has both a catalytic action and a magnetic action ;
The ion conductor is at least one of a compound containing a phosphorus element, a compound containing a sulfur element, and an inorganic solid acid .

  The catalyst-supported mixed conductor of the present invention includes a mixed conductive carrier and a magnetic body.

  Since the mixed conductive carrier has both electron conductivity and ionic conductivity, as in Patent Documents 1 to 8, electrons and protons or oxygen ions are suitably transmitted, and electrons, protons or oxygen ions are transmitted to all catalysts. Since it can be transmitted almost evenly, high reaction efficiency can be realized without wasting the catalyst.

  In particular, in this catalyst-carrying mixed conductor, as shown in FIG. 1, a magnetic body 5 having a magnetic action is carried on the mixed conduction carrier 85. For this reason, for example, in a fuel cell system using this catalyst-supporting mixed conductor, the following effects occur when (1) hydrogen is used as the fuel and (2) when fuel such as methanol is used directly.

(1) When using hydrogen as a fuel In the region of several nanometers near the magnetic body 5, when the distance is R, a large magnetic field gradient is generated in an order of magnitude proportional to 1 / R, and as a result, proportional to the magnetic force. The product of a magnetic field with a magnetic field gradient is very large. For this reason, oxygen receives a very large attractive force of about 10 ⁵ N / m ³ corresponding to about 10 ³ times the gravity from the magnetic body 5 as a paramagnetic material. On the other hand, the water generated on the surface of the catalyst after the electrochemical reaction is about 10 ⁶ N / m ³ corresponding to about 10 ³ times the gravity from the magnetic body as a diamagnetic body due to the magnetic force generated by the magnetic body 5. Receives a very large exclusion force.

  For this reason, when this electrode is used as the cathode electrode of a fuel cell system using hydrogen as a fuel, water can be discharged as a diamagnetic material while oxygen is attracted as a paramagnetic material. For this reason, water as an obstacle is drained from the active point of the catalyst that performs an electrochemical reaction, and oxygen can be quickly supplied thereto, so that flooding is suppressed and the output of the fuel cell system can be improved. .

(2) In the case of directly using fuel such as methanol Unreacted fuel is also subjected to a large displacement force as a diamagnetic material by the magnetic action of the magnetic material 5 carried on the anode pole. For this reason, the unreacted fuel is reliably decomposed by hydrogen ions, electrons, etc. by the anode electrode catalyst. In other words, the crossover phenomenon of unreacted fuel is suppressed.

  The unreacted fuel is also subjected to a large displacement force as a diamagnetic material due to the magnetic action of the magnetic body 5 carried on the cathode pole. For this reason, unreacted fuel is returned to the electrolyte layer side from the vicinity of the interface with the electrolyte layer, and the crossover phenomenon is also suppressed by this. The fuel returned to the electrolyte layer side passes through the gaps between the skeletons in the electrolyte layer, reaches the anode electrode, and reliably generates hydrogen ions, electrons, and carbon dioxide.

  Furthermore, the fuel cannot approach the cathode catalyst and the fuel is not oxidized at the cathode. For this reason, electrons are not generated at the cathode electrode, and positive charges formed at the cathode electrode effectively appear in the output.

  It is also possible to attract oxygen as a paramagnetic substance to the cathode electrode. In addition, free water that is about to move from the electrolyte layer to the cathode electrode and generated water that is generated on the surface of the catalyst in the cathode electrode can be eliminated as a diamagnetic material. Further, the fuel does not become an obstacle on the active point of the catalyst at the cathode. For this reason, oxygen can be quickly supplied thereto, and flooding is suppressed. Also in this respect, the output of the direct fuel cell system is increased.

  Thus, for example, in a fuel cell system, flooding can be prevented and high reaction efficiency and output can be exhibited.

  Therefore, if this catalyst-supported mixed conductor is employed in an electrochemical device, the electrochemical device can exhibit high reaction efficiency and output while realizing prevention of flooding.

  Further, even when a polymer electrolyte is used, the mixed conductive carrier 85 is high enough to bond the catalyst-supported mixed conductor 30 formed by supporting the catalyst 82 and the magnetic body 5 or the magnetic catalyst 6 described later to the substrate. A molecular electrolyte may be used, and it is difficult to hinder gas supply, and performance degradation can be prevented as much as possible. Furthermore, an electrochemical device using this catalyst-supported mixed conductor is unlikely to be accompanied by a dimensional change due to the polymer electrolyte, and thus the supported catalyst is difficult to drop off.

Mixed conductive carrier, similar to the Patent Document 1 to 8, an electron capable conduction electron conductors, electronic conductor and form an integral, ing from the conduction possible ionic conductor ions.

  The electron conductor and ionic conductor are preferably inorganic. Such a mixed conductive carrier exhibits heat resistance and water resistance.

  According to the inventors' tests, the electron conductor can be carbon-based. More particularly, the carbon system can have a continuous bond of carbons including double or triple bonds. In other words, in addition to the type in which the main chain has a carbon double bond or triple bond and both, and the main chain contributes to the electron conduction function, a carbon system that conducts electrons through the side chain is adopted. Can do.

  Such a carbon system is preferably a carbonized organic compound having a π bond. As the organic compound having a π bond, aliphatic hydrocarbons, aromatic hydrocarbons, and derivatives thereof can be employed. As typical examples of these organic compounds, it is possible to use at least one of polyacetylene, resorcinol, phenol, 2-phenylphenol, polyaniline, polypyrrole, polythiophene, phenylphosphonic acid, phenylsilane alkoxides, pyrogallol and dihydroxybiphenyl. it can.

  The electron conductor may also include a carbon system such as graphite and carbon nanotubes, and a metal system including metals such as gold, palladium, platinum, magnesium, lithium, and titanium, and alloys thereof.

Ion conductor, a compound containing phosphorus element can be at least one compound Mono及 beauty inorganic solid acids containing sulfur. In particular, compounds containing phosphorus, phosphoric acid, phosphoric acid esters can be used sulfuric acid, ester sulfate, at least one sulfonic acid and tungstophosphoric acid.

  Covalent bonding, intercalation, and inclusion are possible as fixing modes of the electron conductor and the ionic conductor. However, these modes may be mixed depending on the manufacturing process conditions. Further, depending on the types of materials of the electron conductor and the ionic conductor, whether the immobilization state is covalent bonding, inclusion, or intercalation also changes. For example, when an electron conductor made of an inorganic compound by carbonizing an organic compound is used, it is considered that a covalent bond is mainly used. As another example, when a metal system is selected as the electron conductor, if an inorganic system, particularly an oxide, is selected as the ionic conductor, it is possible to fix it by covalent bonding or inclusion.

  The state in which the electron conductor and the ionic conductor are fixed by a covalent bond is illustrated in FIGS. In the mixed conductive carrier 85, the electron conductor 1 and the ionic conductor 2 are covalently bonded, and the catalyst 82 or the magnetic body 5 is supported on the mixed conductive carrier 85. When the catalyst 82 is not supported on the mixed conductive carrier 85, the magnetic body 5 is used as the magnetic catalyst 6. Since the electron conductor 1 and the ionic conductor 2 are very close to each other, as shown in the drawing, they can come into contact with the nano-order catalyst 82 or the magnetic body 5 (6). For this reason, it becomes possible to supply the electrons and protons or oxygen ions necessary for the catalytic reaction without excess or deficiency.

  Such a catalyst-supporting mixed conductor 30 can be manufactured as follows. First, a polymer precursor obtained by polymerizing an organic compound having a π bond and an ionic conductor is formed. In this polymer precursor, carbons that form the skeleton of the organic compound are polymerized to form an electron conductive main chain having a π bond, and also form a covalent bond with the ionic conductor. It is considered that this ionic conductor is configured to crosslink the carbon main chain of the electronic conductor. By blending a sufficient amount of ionic conductor, the distance between the ionic conductors covalently bonded to the carbon main chain is reduced, and ionic conductivity is generated therebetween.

Alternatively, a precursor in which an ionic conductor is dispersed in a polymer of an organic compound having a π bond may be prepared. When the degree of polymerization between the organic compound and the ionic conductor is small, the result is a precursor in which the ionic conductor is dispersed in the polymer of the organic compound. Further, if the polymerization degree is insufficient, a precursor and an ion conductor with by now separated from the covalently bound ion conductor in the organic compound constituting the electron conductor to the actual quality dispersed state coexist.

  Such a precursor is fired under an inert atmosphere. An inert atmosphere can be achieved by placing the precursor under argon gas, nitrogen gas or helium gas flow or by evacuation. When the precursor is heated under such an inert atmosphere, the organic component is carbonized to become an inorganic substance. Thereby, electronic conductivity is ensured. When the main chain of the organic component has a π bond, high electron conductivity is obtained. The heating temperature and the heating time are appropriately selected according to the characteristics of the precursor.

  High energy other than heat can be applied simultaneously with heating or after heating. Examples of the high energy include plasma irradiation, microwave irradiation, and ultrasonic irradiation.

  Then, the ionic conductor is stably immobilized on the carbon skeleton having electron conductivity. Thereby, ion conductivity is ensured. The ionic conductivity is considered to be obtained by the proximity of the ionic conductor. As shown in FIGS. 2 to 4, when the ion conductor 2 crosslinks the carbon skeleton, the position of the ion conductor 2 is fixed, so that the ion conductivity is ensured by the interaction between the ion conductors 2. .

  When the ion conductor is detached from the carbon skeleton and is not bonded to the carbon skeleton from the precursor state, the ionic conductor is intercalated between the carbon main chains or has a network structure formed by the carbon main chains. It is thought that it is included in. Even in these cases, it is considered that ion conductivity can be obtained if the ion conductors are close to each other.

  Further, when the ion conductor contains phosphorus, it is preferable to heat or pressurize the precursor before firing. By heating or pressure heating the precursor, the phosphorus content after firing increases. The method for heating or pressurizing and heating the precursor is not particularly limited, and a general method can be used.

  The reason for using the reflux method is that, when heating in a boiling state, it is desirable to install a cooler in the reaction vessel in order to liquefy the generated steam and return it to the reaction vessel. According to this reflux method, the temperature can be raised without applying any pressure to the atmosphere of the precursor. The temperature and time for heating are appropriately selected according to the characteristics of the precursor.

  The method of pressurizing and heating the precursor is not particularly limited, but it is preferable to use an autoclave from the viewpoint of workability and the like. The atmospheric pressure and temperature of the precursor are appropriately selected according to the characteristics of the precursor.

  The mixed conduction carrier thus obtained has both an electron conduction function and an ion conduction function, and also functions in a low temperature range of about room temperature. In addition, this mixed conductive carrier stably exhibits an electronic conduction function and an ionic conduction function even in the presence of water.

  As shown in FIG. 1, a catalyst-supported mixed conductor 30 is obtained by supporting the catalyst 82 or the magnetic body 5 on the mixed-conducting carrier 85. When the mixed conductive carrier 85 does not carry the catalyst 82, the magnetic body 5 is used as the magnetic catalyst 6. The method of carrying is not particularly limited, and a well-known method is adopted.

  The magnetic body 5 has a magnetic action. As this magnetic body, it is possible to employ a permanent magnet of a single-component metal or a binary or higher multi-component alloy such as iron, cobalt, nickel, iron-cobalt alloy, iron-nickel alloy, and alnico.

In particular, the magnetic body 5 is a magnetic catalyst 6 having both catalytic action and magnetic action . When the permanent magnet is used as the magnetic body 5, the permanent magnet is merely dispersed and arranged. In this case, since the permanent magnet that draws in oxygen and exhausts the fuel and water is not always close to the catalyst that performs the catalytic action, it seems that the output cannot be improved. In this regard, when the magnetic body 5 is the magnetic catalyst 6, the magnetic action allows the fuel and water to be discharged as a diamagnetic body while attracting oxygen as a paramagnetic body. At this time, the magnetic catalyst 6 itself sucks oxygen, expels fuel and water, and promotes a reduction reaction to catalyze an electrochemical reaction. For this reason, the output improvement of a fuel cell system is realizable more reliably.

  In the direct type fuel cell system, the magnetic body 5 of the anode pole eliminates unreacted fuel. Therefore, if the magnetic body 5 also has a catalytic action, the unreacted fuel is converted into hydrogen ions or the like. May be difficult to disassemble. For this reason, it is less necessary for the magnetic body of the anode pole to have a catalytic action than the magnetic body 5 of the cathode pole.

According to the test results of the inventors, a Pt alloy having a fct structure as a main phase can be adopted as the magnetic catalyst 6. As shown in FIG. 5, the Pt alloy having the fct structure is a Pt alloy in which Pt and another alloy metal such as Fe and Co form a layer structure. As shown in FIG. 6, by subjecting a Pt alloy having a cubic face centered cubic lattice (fcc) structure in which Pt and another alloy metal do not form a layer structure to a heat treatment at a high temperature, a Pt alloy having an fct structure is obtained. can get. Generally, a Pt alloy immediately after alloying has an irregular fcc structure which is a metastable phase, which shows soft magnetic properties. However, when this is subjected to a heat treatment at a high temperature, a regular fct structure which is a stable phase is formed, and a high coercive force exhibiting a high uniaxial crystal magnetic anisotropy of Ku to ⁷ × 10 ⁷ erg / cc is obtained. It will have.

  More specifically, a Pt—Fe alloy can be employed as the magnetic catalyst 6. A phase diagram of the Pt—Fe alloy is shown in FIG. As shown in FIG. 7, when the heat treatment temperature is 900 ° C., a Pt—Fe alloy having a main phase of an fct structure that exhibits a magnetic action in a range of Pt / Fe = 35/65 to 54/46 (at%). Is obtained. According to the tests by the inventors, by setting the heat treatment temperature to 1300 ° C., Pt whose main phase is an fct structure exhibiting a magnetic action in the range of Pt / Fe = 41/59 to 74/26 (at%). A -Fe alloy was obtained. Pt / Fe = 38.5 / 61.5 (at%) Pt—Fe alloy heat-treated at 1046 ° C. for 100 hours and quenched with water. As shown in FIG. FIG. 8 shows that the Pt—Fe alloy having the fct structure as a main phase has a high coercive force of −3.8 to 3.8 kOe. According to the inventors' estimation, it is preferable to employ a Pt—Fe alloy having a composition of Pt / Fe = 40/60 to 75/25 (at%). Moreover, it is preferable to employ a Pt—Fe alloy having a coercive force of 2 kOe or more in absolute value. Furthermore, it is preferable to employ a Pt—Fe alloy having a particle size of 1 to 10 nm. This type of Pt—Fe alloy can be obtained by a reverse micelle method based on an aqueous solution reaction, a synthesis method using an organic metal, or the like.

  Further, as the magnetic catalyst 6, a Pt—Co alloy can also be adopted. A phase diagram of the Pt—Co alloy is shown in FIG. As shown in FIG. 9, a Pt—Co alloy having an fct structure having a magnetic action in the range of Pt / Co = 40/60 to 73/27 (at%) as a main phase is obtained. Moreover, the magnetization curve figure of 50Pt-50Co alloy is shown in FIG. FIG. 10 shows that this Pt—Co alloy also has a high coercive force. According to the inventors' estimation, it is preferable to employ a Pt—Co alloy having a composition of Pt / Co = 40/60 to 75/25 (at%). Moreover, it is preferable to employ a Pt—Co alloy having a coercive force of 2 kOe or more in absolute value. Furthermore, it is preferable to employ a Pt—Co alloy having a particle size of 1 to 10 nm. This type of Pt—Co alloy is also obtained by a reverse micelle method based on an aqueous solution reaction, a synthesis method using an organic metal, or the like.

  The catalyst-supported mixed conductor 30 thus obtained can be dispersed in water or alcohol to produce a paste in which these are mixed, and this paste can be applied to one side of the substrate. PTFE, a polymer electrolyte solution, or the like can be added to the paste. In this way, an electrode or the like having a catalyst layer containing a mixed conductive carrier and a magnetic body can be manufactured.

  Examples 1 to 11 embodying the present invention in a fuel cell system will be described below with tests 1 to 4 together with comparative examples 1 to 4.

Example 1
"First step"
As an organic compound having a double bond, resorcinol having the chemical formula shown in Chemical Formula 1 was used as the first starting material. Further, as a proton conductor, trimethyl phosphate having a chemical formula in Chemical Formula 2 was used as the second starting material.

Then, as shown in Chemical Formula 3, formaldehyde is subjected to nucleophilic addition reaction with resorcinol to obtain a first compound in which —CH ₂ OH is introduced into resorcinol. The molar ratio of resorcinol to formaldehyde is 1: 2.

  Further, as shown in Chemical formula 4, ethyl alcohol, water and hydrochloric acid are added to trimethyl phosphate to obtain a second compound which is a hydrolyzed solution.

Then, the second compound is added to the first compound. At this time, the molar ratio of resorcinol to trimethyl phosphate is 5: 2. After this, Na ₂ CO ₃ as catalyst is added to the mixture. The mixture is allowed to stand at room temperature for several hours in a sealed state, and further gelled by leaving it at 70 ° C. for 2 days in a sealed state. The gel is left to stand at 90 ° C. for 1 day under sealing, and then left at 120 ° C. for several hours under air release. Thus, dehydration condensation polymerization and drying are performed to obtain a precursor. This precursor is presumed to have the chemical formula: Further, the above reaction and the structure of the precursor are schematically shown in FIG.

"Second step"
The precursor is heat-treated at 500 ° C. for 4 hours in a nitrogen gas atmosphere to obtain the mixed conductive carrier 85 of Example 1. As shown in FIG. 2, the mixed conductive carrier 85 has a configuration in which an electron conductor 1 having a skeleton similar to graphite and a proton conductor 2 having a phosphate group are alternately arranged. The obtained mixed conductive carrier 85 is once pulverized by a ball mill or the like.

(Example 2)
The precursor is heat-treated at 800 ° C. for 4 hours in a nitrogen gas atmosphere to obtain the mixed conductive carrier 85 of Example 2.

(Example 3)
The precursor is heat-treated at 1000 ° C. for 4 hours in a nitrogen gas atmosphere to obtain the mixed conductive carrier 85 of Example 3.

(Test 1)
The mixed conductive carrier 85 of Examples 1 to 3 was processed and molded by a press to obtain a plate-like measurement sample. The electrode compositions of Comparative Examples 1 to 3 to which trimethyl phosphate as a proton conductor was not added were produced in the same manner, and the electrode compositions of Comparative Examples 1 to 3 were also used as plate-shaped measurement samples.

"Electronic conductivity"
The measurement samples of Examples 1 to 3 and Comparative Examples 1 to 3 are sandwiched between current collector plates, and the specific resistance (Ω · cm) is calculated based on the voltage when a direct current of 1A, 3A or 5A is applied thereto. did. The results for n = 1 are shown in Tables 1 and 2. The measurement sample of Comparative Example 1 having a heat treatment temperature of 500 ° C. was an insulator showing an electronic specific resistance of 40 MΩ · cm or more.

  From Table 1 and Table 2, it can be seen that the measurement samples of Examples 1 to 3 have excellent electronic conductivity when the heat treatment temperature is 800 ° C or 1000 ° C.

"Proton conductivity"
As shown in FIG. 12, the measurement samples T of Examples 1 to 3 and Comparative Examples 1 to 3 are sandwiched between ion exchange membranes 11a and 11b made of Nafion (registered trademark). Further, carbon cloths 12 and 13 having catalyst layers 12a and 13a made of Pt on one side are prepared, and the ion exchange membranes 11a and 11b are sandwiched between the catalyst layers 12a and 13a. Then, while blocking electrons with the ion exchange membranes 11a and 11b, a voltage is applied between the carbon cloths 12 and 13 in a nitrogen and hydrogen atmosphere at 60 ° C. in a saturated humidity atmosphere, and the proton conductivity is determined from the response current. (S / cm) was calculated. The results for n = 1 are shown in Tables 3 and 4.

  Since this result reflects all the resistance and contact resistance of other members such as an ion exchange membrane of the measurement system, the proton conductivity of the measurement samples themselves of Examples 1 to 3 is higher than this result. Obviously. On the other hand, the proton conductivity of the measurement samples of Comparative Examples 1 to 3 is the measurement lower limit.

  Moreover, the relationship between the applied voltage and the time transition of the response current in the measurement sample of Example 1 is shown in FIG. FIG. 13 shows that when a voltage is applied to the measurement sample of Example 1, no current flows in nitrogen, and a current flows when the gas is changed to hydrogen gas. It can be seen that the measurement samples of Examples 1 to 3 have the same proton conductivity. On the other hand, no response current flows in the measurement samples of Comparative Examples 1 to 3.

(Test 2)
"Third step"
On the other hand, a magnetic catalyst 6 is prepared as the magnetic body 5. This magnetic catalyst 6 has a main phase of an fct structure in which a Pt—Fe alloy having an average particle diameter of 5 nm and Pt / Fe = 50/50 (at%) is heat-treated and rapidly cooled with water.

"4th process"
The magnetic catalyst 6 is supported on the outer peripheral surface of the mixed conductive carrier 85 to obtain the catalyst-supported mixed conductor 30 of Example 1. The loading density of the magnetic catalyst 6 is 30% by mass. The loading was performed by a colloid method, an impregnation method, or the like.

  The prepared catalyst-supporting mixed conductor 30 was dispersed in water or the like, and a cathode electrode paste in which these were mixed was prepared. A PTFE or Nafion (registered trademark) solution is added to the cathode electrode paste. As shown in FIG. 14, this cathode electrode paste was applied to one side of a substrate 10 made of carbon cloth and dried to form a cathode catalyst layer 22a. Thus, the cathode electrode 22 of Example 1 was manufactured. The portion other than the cathode catalyst layer 22a in the cathode electrode 22 is constituted by the base material 10, which is a cathode diffusion layer that diffuses air to the cathode catalyst layer 22a on the non-electrolyte side.

  On the other hand, carbon powder carrying platinum at 40 wt% was dispersed in water or the like to prepare an anode electrode paste. A solution of Nafion (registered trademark) is added to the anode electrode paste. This anode electrode paste was applied to one side of a substrate 10 made of carbon cloth and dried to form an anode catalyst layer 21a. Thus, the anode 21 was manufactured. The portion other than the anode catalyst layer 21a in the anode 21 is also constituted by the base material 10, which is an anode diffusion layer that diffuses air to the anode catalyst layer 21a on the non-electrolyte side.

  Then, the electrolyte membrane 23 which consists of Nafion (trademark) was laminated | stacked, and it joined by hot press, and obtained MEA20. The obtained MEA 20 was sandwiched between current collector plates 31 and 32, and cooling plates 33 and 34 were further provided at both ends, and sandwiched between separators 35 and 36. The separators 35 and 36 are formed with cooling water passages 35a, 35b, 36a and 36b and gas passages 35c, 35d, 36c and 36d.

(Test 3)
Using the apparatus shown in FIG. 14, while introducing hydrogen gas into the anode catalyst layer 21a and introducing air at atmospheric pressure into the cathode catalyst layer 22a of Example 1 and Comparative Example 4, characteristics as the MEA 20 at 50 ° C. Was measured. The cathode catalyst layer 22a of Comparative Example 4 uses a cathode electrode paste obtained by supporting Pt on the outer peripheral surface of the mixed conductive carrier 85 used in Example 1. The loading density of Pt is 30% by mass. The results are shown in FIG.

  From FIG. 15, it can be seen that the cell using the cathode catalyst layer 22 a of Example 1 exhibits a desired current-voltage characteristic than the cell using the cathode catalyst layer 22 a of Comparative Example 4. Thereby, since the power generation reaction has occurred, it can be seen that the produced catalyst-supporting mixed conductor 30 has catalytic activity.

(Test 4)
In the apparatus shown in FIG. 14, the magnetic force at room temperature acting on oxygen or air in the vicinity of the catalyst-supporting mixed conductor 30 is simulated. The result is shown in FIG. A solid line indicates a magnetic force acting on air, and a broken line indicates a magnetic force acting on pure oxygen. From FIG. 16, oxygen and air have a very large attractive force of about ^{5 5} N / m ³ from the magnetic body 5 as the magnetic catalyst 6 as a paramagnetic body in the region of several nm in the vicinity of the catalyst-carrying mixed conductor 30. I understand that

In this apparatus, the magnetic force at room temperature acting on water in the vicinity of the catalyst-supporting mixed conductor 30 is simulated. The result is shown in FIG. From FIG. 17, it can be seen that water receives a very large displacement force of about 10 ⁶ N / m ³ from the magnetic catalyst 6 as a diamagnetic material due to the magnetic force generated by the magnetic body 5 as the magnetic catalyst 6. .

  From the above tests 1 to 4, it can be seen that the fuel cell system employing the cathode electrode 22 of Example 1 can prevent flooding and exhibit high reaction efficiency and output. The same applies to the case where the catalyst-supported mixed conductor 30 of Examples 2 and 3 is used.

  Therefore, if the catalyst-supported mixed conductor 30 of Example 1 is employed in an electrochemical device, the electrochemical device can exhibit high reaction efficiency and output while realizing prevention of flooding.

  As said catalyst carrying | support mixed conductor 30, the thing of the following Examples 4-11 can also be employ | adopted.

Example 4
The gel obtained in the first step of Example 1 was pulverized and refluxed in an oil bath at a temperature of 200 ° C. for 4 hours in the second compound. The obtained sample was filtered, dried, and heat-treated (1000 ° C., 4 hours) in an inert gas atmosphere. A catalyst-supported mixed conductor 30 was obtained using the mixed conductive carrier 85 thus obtained. Other conditions are the same as in the first embodiment.

(Example 5)
Sodium carbonate was added to the mixture obtained in the first step of Example 1, and the mixture was stirred at room temperature for 3 hours, and then allowed to stand at 60 ° C. for 24 hours and further at 80 ° C. for 24 hours. Thereafter, the sample was heated at 150 ° C. for 6 hours under a pressure of 3 to 4 MPa in an autoclave. A catalyst-supported mixed conductor 30 was obtained using the mixed conductive carrier 85 thus obtained. Other conditions are the same as in the first embodiment.

(Example 6)
2 g of phenol was dissolved in a mixed solution of 30 cc of pure water and 5 cc of ethanol, and 3.15 cc of a formaldehyde solution was further added. Thereafter, 4.89 cc of a trimethyl phosphate solution was added and stirred for 1 hour, 0.089 g of sodium carbonate was added, and the mixture was stirred overnight at room temperature. The solution was allowed to stand at 70 ° C. for 24 hours under sealing, and then the solvent was removed. The obtained sample was heat-treated at 500 ° C. for 4 hours in a nitrogen gas atmosphere. A catalyst-supported mixed conductor 30 was obtained using the mixed conductive carrier 85 thus obtained. Other conditions are the same as in the first embodiment.

(Example 7)
2 g of pyrogallol was dissolved in 8 cc of pure water, and 2.36 cc of a formaldehyde solution was further added. Thereafter, 3.65 cc of a trimethyl phosphate solution was added and stirred for 1 hour, 0.0167 g of sodium carbonate was added, and the mixture was stirred at room temperature for 3 hours. The mixture was allowed to stand at 50 ° C. for 24 hours under sealing, and further allowed to stand at 80 ° C. for 72 hours. A catalyst-supported mixed conductor 30 was obtained using the mixed conductive carrier 85 thus obtained. Other conditions are the same as in the first embodiment.

(Example 8)
3 g of dihydroxybiphenyl was dissolved in 12 cc of ethanol / water mixed solution with a volume ratio of 1/1, and 4.84 cc of formaldehyde solution was further added. Thereafter, 7.49 cc of a trimethyl phosphate solution was added and stirred for 1 hour, 0.0683 g of sodium carbonate was added, and the mixture was stirred at room temperature for 3 hours. The mixture was allowed to stand at 50 ° C. for 24 hours under sealing, and further allowed to stand at 80 ° C. for 72 hours. The solvent was evaporated, and the obtained sample was subjected to heat treatment at 500 ° C. for 4 hours in a nitrogen gas atmosphere. A catalyst-supported mixed conductor 30 was obtained using the mixed conductive carrier 85 thus obtained. Other conditions are the same as in the first embodiment.

Example 9
3 g of resorcinol was dissolved in 12 cc of pure water, and 4.05 cc of a formaldehyde solution was added. While stirring, 0.736 cc of an aqueous phosphoric acid solution was gradually added. The solution was allowed to stand at 70 ° C. for 24 hours under sealing, and then the solvent was removed. The obtained sample was heat-treated at 1000 ° C. for 4 hours in a nitrogen gas atmosphere. A catalyst-supported mixed conductor 30 was obtained using the mixed conductive carrier 85 thus obtained. Other conditions are the same as in the first embodiment.

(Example 10)
Resorcinol (3 g) was dissolved in 12 cc of pure water, and 4.05 cc of a formaldehyde solution was further added. This was followed by the addition of 0.028 g sodium carbonate. The gel was pulverized after standing at 50 ° C. for 24 hours and at 80 ° C. for 72 hours. The crushed gel was washed with a 0.1N hydrochloric acid aqueous solution, pure water, and ethanol in this order. Then, a solution in which 1.5 g of tungstophosphoric acid was dissolved in 50 cc of ethanol was prepared, and the washed gel was immersed in this solution. The gel soaked at 50 ° C. for 48 hours was subjected to heat treatment at 700 ° C. for 4 hours in a nitrogen gas atmosphere. A catalyst-supported mixed conductor 30 was obtained using the mixed conductive carrier 85 thus obtained. Other conditions are the same as in the first embodiment.

Example 11
Resorcinol (3 g) was dissolved in 12 cc of pure water, and 4.05 cc of a formaldehyde solution was further added. A solution dissolved in ethanol / pure water having a volume ratio of 1/1 was prepared, 2.18 g of phenylphosphonic acid was added to the solution, and 0.114 g of sodium carbonate was further added. After stirring at room temperature for 12 hours, the mixture was allowed to stand for 24 hours at 60 ° C and 48 hours at 80 ° C in a sealed state. The obtained gel was heat-treated at 800 ° C. for 4 hours in a nitrogen gas atmosphere. A catalyst-supported mixed conductor 30 was obtained using the mixed conductive carrier 85 thus obtained. Other conditions are the same as in the first embodiment.

  In the above, the present invention has been described with reference to the first to eleventh embodiments. However, the present invention is not limited to the first to eleventh embodiments, and can be applied with appropriate modifications without departing from the spirit of the present invention. Needless to say. For example, as the mixed conductive carrier 85, those disclosed in Patent Documents 1 to 8 can be adopted. Also by these, the same effect as Example 1 can be produced.

  The present invention can be used for fuel cell systems, sensors, and the like.

It is a conceptual diagram which shows the structure of the catalyst carrying | support mixed conductor of this invention, and the magnetic force to methanol, oxygen, and water. It is a schematic diagram which shows the structure of the catalyst carrying | support mixed conductor of this invention. It is a schematic diagram which shows the structure of the catalyst carrying | support mixed conductor of this invention. It is a schematic diagram which shows the structure of the catalyst carrying | support mixed conductor of this invention. FIG. 3 is a schematic structural diagram of a Pt alloy having an fct structure. It is a schematic structure diagram of a Pt alloy having an fcc structure. It is a phase diagram of a Pt-Fe alloy. FIG. 4 is a magnetization curve diagram of a Pt—Fe alloy having an fct structure as a main phase. It is a phase diagram of a Pt-Co alloy. It is a magnetization curve figure of a Pt-Co alloy. 2 is a schematic diagram showing a reaction for obtaining the precursor of Example 1 and the structure of the precursor. FIG. FIG. 4 is a schematic cross-sectional view of a configuration for measuring proton conductivity of a measurement sample according to Test 1. 4 is a graph showing a relationship between applied voltage and time transition of response current in the measurement sample of Example 1 according to Test 1. It is sectional drawing which shows the apparatus which concerns on the tests 3 and 4 and measures the characteristic of the cell of a fuel cell. 4 is a graph comparing the characteristics of a cell having a cathode catalyst layer of Example 1 and a cell having a cathode catalyst layer of a comparative example according to Test 3. It is a graph which concerns on the test 4 and shows the attraction force which acts on the oxygen or air of the catalyst carrying | support mixed conductor vicinity. It is a graph which shows the exclusion force which concerns on the test 4 and acts on the water of the catalyst carrying | support mixed conductor vicinity. It is related and is a schematic diagram of a membrane electrode assembly. It is a schematic diagram which shows the conventional catalyst carrying | support carbon. It is a schematic diagram which shows the conventional catalyst carrying | support mixed conductor.

Explanation of symbols

85 ... Mixed conductive carrier 5 ... Magnetic body 1 ... Electronic conductor 2 ... Ion conductor (proton conductor)
6 ... Magnetic catalyst

Claims (12)

A mixed conduction carrier composed of an electron conductor capable of conducting electrons and an ion conductor which is integral with the electron conductor and capable of conducting ions , and is supported on the mixed conduction carrier and has both catalytic action and magnetic action. A catalyst-supported mixed conductor comprising a magnetic body, which is a magnetic catalyst ,
The catalyst-supported mixed conductor , wherein the ion conductor is at least one of a compound containing a phosphorus element, a compound containing a sulfur element, and an inorganic solid acid . 2. The catalyst-carrying mixed conductor according to claim 1, wherein the mixed conductive carrier has a configuration in which the electron conductor and the ionic conductor are alternately arranged. 3. The catalyst-supported mixed conductor according to claim 1, wherein the compound containing phosphorus element is at least one of phosphoric acid, phosphoric ester and tungstophosphoric acid. 4. The catalyst-carrying mixed conductor according to claim 3, wherein the compound containing phosphorus element is trimethyl phosphate, phosphoric acid or tungstophosphoric acid. The catalyst-supporting mixed conductor according to any one of claims 1 to 4, wherein the electron conductor and the ionic conductor are inorganic. The catalyst-supported mixed conductor according to claim 5, wherein the electron conductor is carbon-based. The catalyst-supported mixed conductor according to claim 6 , wherein the carbon system has a continuous bond of carbon including a double bond or a triple bond. The catalyst-supported mixed conductor according to claim 7 , wherein the carbon-based material is a carbonized product of at least one of aliphatic hydrocarbons, aromatic hydrocarbons, and derivatives thereof. The carbon system is characterized by carbonizing at least one of polyacetylene, resorcinol, phenol, 2-phenylphenol, polyaniline, polypyrrole, polythiophene, phenylphosphonic acid, phenylsilane alkoxides, pyrogallol and dihydroxybiphenyl. The catalyst-supported mixed conductor according to claim 8 . The magnetic catalyst catalyst supporting mixed conductor of any one of claims 1 to 9, characterized in that a Pt alloy of which main phase fct structure. The catalyst-supported mixed conductor according to claim 10, wherein the magnetic catalyst is a Pt-Fe alloy. The catalyst-supported mixed conductor according to claim 10, wherein the magnetic catalyst is a Pt—Co alloy.

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