JP2018184532A - Metallophthalocyanine polymer composite, electrode catalyst using the same and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metallophthalocyanine polymer composite as a production raw material for an electrode catalyst having high oxygen reduction activity.SOLUTION: The metallophthalocyanine polymer composite comprises a metallophthalocyanine polymer having a repeating structural unit in which a tetraamino metallophthalocyanine structural unit and a tetracarboxy metallophthalocyanine structural unit are amide-bonded and a carbon material and has a blending ratio based on the weight of the metallophthalocyanine polymer to the carbon material in the range of 1:1 to 25:1. In the polymer composite, the metals are each a divalent or trivalent metal ion belonging to the third period to the fifth period in the long period type periodic table. In the metallophthalocyanine polymer composite, the central metal is preferably selected from Co, Niand Fe.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a metal phthalocyanine polymer composite, an electrocatalyst using the same, and a method for producing the same, and in particular, to a metal phthalocyanine polymer composite that can be suitably used for an electrode of a fuel cell, an electrocatalyst using the metal phthalocyanine polymer composite and the same. It relates to a manufacturing method.

  Currently we use fossil fuels as our main energy source. However, fossil fuels are finite. Furthermore, the fossil fuel has a problem that carbon dioxide generated during use promotes the greenhouse effect. Therefore, there is a need to develop an energy source that can replace fossil fuels. One of new energy sources is a fuel cell.

  Compared to primary batteries and secondary batteries, fuel cells are power generators that can be used semipermanently by continuously supplying hydrogen or oxygen as fuel. The fuel cell is also attracting attention because the fuel used can be reused. Among them, a polymer electrolyte fuel cell (PEFC) operates at a low temperature and can be reduced in size and weight because the electrolyte is a thin film, so that it can be used for home appliances, portable devices, and automobile batteries. Application to batteries is expected. PEFC has a structure in which an electrolyte membrane is sandwiched between two electrodes, a cathode (positive electrode) and an anode (negative electrode). In PEFC, fuel such as oxygen is supplied to the positive electrode and hydrogen is supplied to the negative electrode, and electric energy can be obtained from a chemical reaction occurring at the electrode.

  The cathode of the fuel cell carries an electrode catalyst and catalyzes the reaction of reducing oxygen to water. Since the oxygen reduction reaction on the cathode side has a relatively slow reaction rate, a catalyst is required to operate it efficiently. Carbon-based materials are known as electrode materials, but platinum-containing catalysts are currently most effective as carbon-based electrode catalysts for efficiently operating fuel cells. However, since platinum is a noble metal, problems in terms of cost have been pointed out. Therefore, creation of a novel catalyst that does not use platinum is expected.

By the way, what is important in the creation of a carbon-based electrode catalyst is to create a highly dispersible carbon material having high conductivity and a large surface area, and finely disperse the metal in the material. As one of such carbon material materials, phthalocyanine is known (see, for example, Patent Document 1). The carbon material described in this document is obtained by firing hyperbranched metal phthalocyanine composed of a specific repeating unit in an inert gas atmosphere. Metal ions constituting the phthalocyanine core of this repeating ^unit, Fe 2+, ^Co 2+, to be selected from the group consisting of Ni ^2+, is characterized in that it is not necessary to use an expensive noble metal such as platinum.

  It is known that phthalocyanine contains a lot of coordinating elements for fixing metals. Phthalocyanine has a huge cyclic structure in which the entire molecule forms a conjugated double bond system, so its structure and bond are extremely stable. At the center of the molecule, it coordinates to a metal ion such as a transition metal. Form a stable metal phthalocyanine complex. An advantage of using metal phthalocyanine as an electrode material is that metal can be stably immobilized, that is, it can be suggested that metal arrangement can be controlled at the nano level. Further, the advantage of using metal phthalocyanine as a precursor of the metal-supporting carbon material is that the carbon content is high. That is, when the phthalocyanine is baked into a carbonized product, the carbon content of the electrode can be increased.

  The present inventors have produced a metal phthalocyanine polymer obtained by condensing a metal aminophthalocyanine compound and a metal carboxyphthalocyanine compound (see, for example, Patent Document 1). According to this conventional metal phthalocyanine polymer, it is suitably used as a precursor of an electrocatalyst material in particular, it is composed of simple structural units, the metals are regularly arranged, and, if necessary, for searching for the cooperative effect of different metals. Can also be suitably used.

  Furthermore, the present inventors have produced an electrode catalyst obtained by calcining the above metal phthalocyanine polymer into a calcined product and then treating with an acid such as aqua regia (see, for example, Patent Document 2). . This conventional electrode catalyst has high oxygen reduction activity and excellent electrode characteristics.

International Publication No. 2014/175077 International Publication No. 2015/146858

  In Patent Document 2, an electrode catalyst having a relatively high oxygen reduction activity is obtained by acid-treating a fired product of a metal phthalocyanine polymer. However, in recent years, the demand for characteristics required for an electrode catalyst has increased, and an electrode catalyst with higher oxygen reduction activity has been demanded.

  An object of the present invention is to provide a metal phthalocyanine polymer composite which is a raw material for producing an electrode catalyst having a high oxygen reduction activity. Another object of the present invention is to provide an electrode catalyst having a high oxygen reduction activity and a method for producing the same.

  In view of the situation as described above, the present inventors have conducted intensive research on an electrode catalyst material. As a result, the present inventors have found that an electrode catalyst obtained by calcining a composite of a metal phthalocyanine polymer and a carbon material has higher oxygen reduction activity than before, and has completed the present invention.

（一般式（１ａ）中、Ｌは長周期型周期表の第３〜第５周期に属する２価又は３価の金属イオンである。）

（一般式（２ａ）中、Ｍは長周期型周期表の第３〜第５周期に属する２価又は３価の金属イオンである。） That is, the present invention contains a metal phthalocyanine polymer having a repeating structural unit in which the structural unit represented by the general formula (1a) and the structural unit represented by the general formula (2a) are amide-bonded, and a carbon material. Further, the present invention relates to a metal phthalocyanine polymer composite characterized in that a compounding ratio of the metal phthalocyanine polymer and the carbon material is in a range of 1: 1 to 25: 1 on a weight basis.

(In general formula (1a), L is a divalent or trivalent metal ion belonging to the third to fifth periods of the long-period periodic table.)

(In general formula (2a), M is a divalent or trivalent metal ion belonging to the third to fifth periods of the long-period periodic table.)

In this case, it is preferable that the L and the M are each independently a metal ion selected from the group consisting of Co ²⁺ , Ni ²⁺ and Fe ²⁺ . Further, the L and the M are preferably Co ²⁺ , the L is Co ²⁺ , the M is Ni ²⁺ , or the L is Co ²⁺ , and the M is Fe ^2+. . Furthermore, in the above case, it is preferable that the carbon material is carbon black.

Further, the present invention is an electrode catalyst comprising a fired product of the above metal phthalocyanine polymer composite, and in linear sweep voltammetry using a working electrode in which the electrode catalyst is applied to a disk electrode, the oxygen solution is used as an electrolyte and Using a 0.5 M sulfuric acid aqueous solution at the time of nitrogen saturation, a platinum plate as an auxiliary electrode, and an Ag / AgCl electrode as a reference electrode, the disk electrode for each of the electrolytic solution at the time of oxygen saturation and the electrolytic solution at the time of nitrogen saturation Electrode catalyst having electrode characteristics satisfying the following conditions (a) and (b) when swept from a sweep range of 950 mV to -400 mV at a sweep speed of 1 mV / sec under the condition of a rotational speed of 2000 rpm: About.
<Electrode characteristics>
When the current value of the difference between the current value when measuring the electrolytic solution at the time of oxygen saturation and the current value when measuring the electrolytic solution at the time of nitrogen saturation is the differential current value (I _diff ),
(A) The oxygen reduction starting potential (E ₀ ) at which the differential current value (I _diff ) is −1.0 × 10 ⁻⁶ A is 500 mV or more,
(B) The differential current value (I _diff ) at a potential of 0 mV is −2.0 × 10 ⁻⁴ A or less.

  Furthermore, the present invention relates to an electrode catalyst produced by firing the above metal phthalocyanine polymer composite at 650 to 1500 ° C. in a reducing gas atmosphere or an inert gas atmosphere. In this case, the calcination is preferably performed at 800 to 1000 ° C. in a reducing gas atmosphere.

  Furthermore, it is preferable to further acid-treat the metal phthalocyanine polymer composite after firing. In this case, the acid is preferably at least one selected from the group consisting of diluted hydrochloric acid, concentrated hydrochloric acid, diluted sulfuric acid, concentrated sulfuric acid, diluted nitric acid, concentrated nitric acid, and aqua regia. Furthermore, in this case, the acid is preferably aqua regia.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the metal phthalocyanine polymer composite which is a manufacturing raw material of an electrode catalyst with high oxygen reduction activity. Moreover, according to this invention, it becomes possible to provide an electrode catalyst with high oxygen reduction activity, and its manufacturing method.

It is a graph which shows the result of having tested the electrode produced using the sample of an Example and a comparative example, and the electrode produced with the normal platinum catalyst by the linear sweep voltammetry method. It is IR spectrum figure of tetranitro cobalt phthalocyanine (2). It is IR spectrum figure (a) and ultraviolet absorption spectrum figure (b) of tetraamino cobalt phthalocyanine (M1). It is IR spectrum figure of tetracarboxyamide cobalt phthalocyanine (4). It is IR spectrum figure (a) and ultraviolet absorption spectrum figure (b) of tetracarboxy cobalt phthalocyanine (M2). 2 is an IR spectrum diagram of the carbon black-containing cobalt phthalocyanine complex (P1 [Co—Co] + CB (2: 1)) of Example 1. FIG. 4 is an IR spectrum diagram of a carbon black-containing cobalt phthalocyanine complex (P1 + CB (10: 1)) of Example 2. FIG. 4 is an IR spectrum diagram of a carbon black-containing cobalt phthalocyanine complex (P1 + CB (20: 1)) of Example 3. FIG. 4 is an IR spectrum diagram of a carbon black-containing cobalt phthalocyanine complex (P1 + CB (30: 1)) of Comparative Example 2. FIG. It is a graph which shows the result of having tested with the linear sweep voltammetry method about the electrode produced in Example 1, and the electrode which processed this with aqua regia.

  Hereinafter, the metal phthalocyanine polymer composite, the electrode catalyst, and the production method thereof of the present invention will be described in detail.

1. Metal phthalocyanine polymer composite The metal phthalocyanine polymer composite (hereinafter simply referred to as “metal phthalocyanine polymer composite”) which is a precursor of the electrode catalyst of the present invention contains a metal phthalocyanine polymer and a carbon material. Hereinafter, each component will be described in detail.

(1) Metal phthalocyanine polymer The metal phthalocyanine polymer (hereinafter simply referred to as “metal phthalocyanine polymer”) contained in the metal phthalocyanine polymer composite of the present invention comprises a structural unit represented by the general formula (1a) and a general formula (2a ) And a structural unit represented by amide bond.

（一般式（１ａ）中、Ｌは長周期型周期表の第３〜第５周期に属する２価又は３価の金属イオンである。）

(In general formula (1a), L is a divalent or trivalent metal ion belonging to the third to fifth periods of the long-period periodic table.)

（一般式（２ａ）中、Ｍは長周期型周期表の第３〜第５周期に属する２価又は３価の金属イオンである。）

(In general formula (2a), M is a divalent or trivalent metal ion belonging to the third to fifth periods of the long-period periodic table.)

  As described above, the metal phthalocyanine polymer has a hyperbranch structure in which the repeating units of the general formula (1a) and the repeating units of the general formula (2a) are alternately arranged. Therefore, the metal M and the metal L of the phthalocyanine core contained in each repeating unit are arranged regularly and alternately.

Here, as a bivalent metal ion which comprises L and M, Mg ^<2+> , Ca ^<2+> , Sr <^2+> , Cd <^2+> , Ni < ^{2+ >} , Zn ^<2+> , Cu ^<2+> , Fe ^<2+> , Co ^<2+> , Sn ^<2+> , Mn ^<2+>, etc. Can be mentioned. Examples of the trivalent metal ion include Al ³⁺ , Fe ³⁺ and Cr ³⁺ . As described above, in the present invention, no noble metal such as platinum is used, so that an inexpensive metal phthalocyanine polymer can be provided.

Among these, L and M are each independently a ^Co 2 ^+, Ni 2 ^+, is preferably a metal ion selected from the group consisting of Fe ² +. These three types of metal ions are transition metals, can be complexed with various ligands, are relatively readily available and inexpensive, have low toxicity, and are superior to other metal ions for these reasons. Therefore, it is preferable. In particular, if L and M are Co ² +, or L is M is Ni ² + is Co ² +, L it is preferred Co ² is + M is Fe ² +. Thus, by making L and M different metals, it becomes possible to search for the cooperative effect of different metals when a metal phthalocyanine polymer is baked into a carbon electrode material as described later. In addition, it is preferable to include a dissimilar metal in the electrode catalyst because a mixing effect of dissimilar metals generally found in an organic chemical catalytic reaction can be obtained as compared with a case where only one kind of metal is included.

(2) Carbon Material The carbon material (hereinafter simply referred to as “carbon material”) contained in the metal phthalocyanine polymer composite of the present invention is a material mainly composed of carbon. Examples of the carbon material include carbon black, carbon nanotube, carbon nanofiber, carbon nanocoil, fullerene, carbon fiber, and graphite. As the carbon material, carbon black is preferable, and a conductive material is particularly preferable. There is no restriction | limiting in particular as a kind of carbon black, Furnace black, channel black, acetylene black, thermal black, ketjen black, etc. can be used. The form of carbon black may be either powdered or granular. Moreover, the primary particle diameter of carbon black is usually in the range of 1 to 500 m, preferably in the range of 10 to 50 nm. The BET specific surface area of carbon black is usually in the range of 100 to 5000 m ² / g, and preferably in the range of 500 to 2000 m ² / g. The carbon black preferably has a structure in which the primary particles have a hollow shell-like structure, and the porosity in that case is usually in the range of 30 to 99%, preferably in the range of 50 to 80%. In the present specification, the term “CB” means “carbon black”.

  Specific examples of the carbon black used in the present invention include “Ketjen Black EC-600JD” (manufactured by Lion Corporation), “Ketjen Black ECP-600” (manufactured by Lion Corporation), and “Ketjen Black EC-300J”. "(Made by Lion Corporation)," carbon ECP "(made by Lion Corporation). “Carbon ECP600JD” (manufactured by Lion Corporation), “# 3950B” (manufactured by Mitsubishi Chemical Corporation), “Black Pearls 2000” (manufactured by Cabot Corporation), “Printex XE2B” (manufactured by Degussa Corporation), and the like.

(3) Compounding ratio of metal phthalocyanine polymer and carbon material The compounding ratio of metal phthalocyanine polymer and carbon material in the metal phthalocyanine polymer composite is in the range of 1: 1 to 25: 1 on a weight basis. That is, the compounding ratio of the metal phthalocyanine polymer to the carbon material (weight of the metal phthalocyanine polymer / weight of the carbon material) is in the range of 1 to 25 times. If the blending ratio is less than 1 (that is, the blending ratio is 1: 1), the ratio of the metal phthalocyanine polymer to the carbon material becomes too small, so that the oxygen reduction activity of the obtained electrode catalyst tends to be low. On the other hand, when the blending ratio exceeds 25 times (that is, blending ratio 25: 1), the ratio of the carbon material to the metal phthalocyanine polymer becomes too small, and the oxygen reduction activity of the obtained electrode catalyst tends to be low. The compounding ratio of the metal phthalocyanine polymer and the carbon material is preferably in the range of 10: 1 to 22: 1, more preferably in the range of 15: 1 to 21: 1.

Here, the oxygen reduction activity means an electrode characteristic evaluated by an oxygen reduction start potential (E ₀ ) described later and a differential current value (I _{diff = 0} ) at a potential of 0 mV. The high oxygen reduction activity means that the oxygen reduction start potential (E ₀ ) is high and the value of the differential current value (I _{diff = 0} ) at a potential of 0 mV is negatively large.

(4) Others The metal phthalocyanine polymer composite of the present invention may contain components other than the metal phthalocyanine polymer and the carbon material as long as the effects of the present invention are not inhibited. Examples of such components include a dispersant, a thickener, and a pigment. The content of these components can be appropriately set within a range not inhibiting the effect of the present invention, but is usually 10% by mass or less, preferably 1% by mass with respect to the total amount of the metal phthalocyanine polymer and the carbon material. Or less, more preferably 0.1% by mass or less.

2. Method for producing metal phthalocyanine polymer composite A metal phthalocyanine polymer composite is produced by mixing a metal phthalocyanine polymer and a carbon material so that the blending ratio is within a range of 1: 1 to 25: 1 on a weight basis. Can do. Hereinafter, the manufacturing method of a metal phthalocyanine polymer is demonstrated.

(1) Method for Producing Metal Phthalocyanine Polymer A metal phthalocyanine polymer is synthesized by synthesizing a metal aminophthalocyanine compound represented by the general formula (1) (Step 1) and represented by the general formula (2). It can be produced by synthesizing a metal carboxyphthalocyanine compound (step 2) and condensing the obtained metal aminophthalocyanine compound and metal carboxyphthalocyanine compound (step 3). Hereinafter, each step will be described in detail.

（一般式（１）中、Ｌは長周期型周期表の第３〜第５周期に属する２価又は３価の金属イオンである。）

(In General Formula (1), L is a divalent or trivalent metal ion belonging to the third to fifth periods of the long-period periodic table.)

（一般式（２）中、Ｍは長周期型周期表の第３〜第５周期に属する２価又は３価の金属イオンである。）

(In General Formula (2), M is a divalent or trivalent metal ion belonging to the third to fifth periods of the long-period periodic table.)

(A) Synthesis of metal aminophthalocyanine compound (step 1)
The metal aminophthalocyanine compound represented by the general formula (1) is obtained by synthesizing a metal nitrophthalocyanine compound (step 1-1) and reducing the nitro group of the synthesized metal nitrophthalocyanine compound to an amino group (step 1-2). Can be synthesized. Hereinafter, these steps will be described in detail.

(A-1) Production of metal nitrophthalocyanine compound (step 1-1)
The metal nitrophthalocyanine compound represented by the following general formula (4) is a 4-nitrophthalic acid represented by the following general formula (3), or an acid anhydride or imide thereof, a metal salt containing L, urea, and A catalyst can be manufactured by making it react in presence of a solvent as needed. Examples of the metal salt containing L include cobalt (II) chloride, nickel (II) chloride, and iron (II) chloride. Examples of the catalyst include ammonium molybdate. Examples of the solvent include nitrobenzene, trichlorobenzene, triglyme and the like. Although reaction temperature and reaction time can be set suitably, it can be set as 150-230 degreeC and 4 to 12 hours, for example. As methods for synthesizing metal nitrophthalocyanine, reference can be made to, for example, JP-A-11-56989, JP-A-10-101673, JP-A-53-75223, and the like.

(A-2) Production of metal aminophthalocyanine compound (step 1-2)
The metal aminophthalocyanine represented by the following general formula (1) can be produced by reducing the nitro group of the metal nitrophthalocyanine represented by the following general formula (4). The reduction can be performed using a reducing agent and an appropriate solvent. Examples of the reducing agent include sodium sulfide (Na ₂ S, Na ₂ S _{2 and the} like), sodium hydrosulfide, sodium dithionite, ammonium sulfide, and the like. In this case, water can be mentioned as the solvent, and water also serves as a proton source. Although reaction temperature and reaction time can be set suitably, it can be set, for example as 50-80 degreeC and 4-12 hours. As a method for synthesizing metal aminophthalocyanine, for example, JP-A No. 11-56889, “New Experimental Chemistry Lecture 14 Synthesis and Reaction of Organic Compounds III, pp. 1332-1335, (1978), Maruzen Co., Ltd.” You can refer to it.

(B) Synthesis of metal carboxyphthalocyanine compound (step 2)
The metal carboxyphthalocyanine compound represented by the general formula (2) is synthesized by synthesizing a metal carboxamide phthalocyanine compound (step 2-1) and hydrolyzing the carboxamide group of the synthesized metal carboxamide phthalocyanine compound (step 2-2). can do. Hereinafter, these steps will be described in detail.

(B-1) Production of metal carboxamide phthalocyanine compound (step 2-1)
A metal carboxamide phthalocyanine compound represented by the following general formula (6) is prepared by adding a metal salt containing M, urea, and a catalyst to the trimellitic anhydride represented by the following general formula (5), and, if necessary, a solvent. It can manufacture by making it react in presence. Examples of the metal salt containing M include cobalt (II) chloride, nickel (II) chloride, and iron (II) chloride. Examples of the catalyst include ammonium molybdate. Examples of the solvent include nitrobenzene, trichlorobenzene, triglyme and the like. Although reaction temperature and reaction time can be set suitably, it can be set as 150-230 degreeC and 4 to 12 hours, for example. As methods for synthesizing metal carboxamide phthalocyanine, reference can be made to, for example, JP-A-11-56989, JP-A-10-101673, JP-A-53-75223, and the like.

(B-2) Production of metal carboxyphthalocyanine compound (step 2-2)
The metal carboxyphthalocyanine compound represented by the following general formula (2) can be produced by hydrolyzing the carboxamide group of the metal carboxamide phthalocyanine represented by the following general formula (6). Hydrolysis can be carried out by methods commonly used by those skilled in the art. Hydrolysis can be performed using an aqueous alkali solution such as an aqueous potassium hydroxide solution or an aqueous sodium hydroxide solution. Although reaction temperature and reaction time can be set suitably, they can be 80-120 degreeC and 20-30 hours, for example. As a method for synthesizing metal carboxyphthalocyanine, for example, JP-A No. 11-56889, “New Experimental Chemistry Course 14 Synthesis and Reaction II of Organic Compounds, 943-947, (1977), Maruzen Co., Ltd.” You can refer to it.

(C) Production of metal phthalocyanine polymer (Step 3)
The metal phthalocyanine polymer represented by the following general formula (7) has an amino group of the metal aminophthalocyanine compound represented by the following general formula (1) and a carboxyl group of the metal carboxyphthalocyanine compound represented by the following general formula (2). It can be produced by forming an amide bond. The condensation reaction is preferably performed in the presence of a condensing agent. Examples of the condensing agent include, but are not limited to, triphenyl phosphite. When triphenyl phosphite is used as the condensing agent, it is preferable to use pyridine. Furthermore, when triphenyl phosphite is used as the condensing agent, a metal salt such as lithium chloride or calcium chloride can be added. The condensation reaction can be carried out in the presence of a solvent. Examples of the solvent used in the condensation reaction include dimethylformamide (DMF) and N-methylpyrrolidone (NMP).

  The ratio of the metal aminophthalocyanine compound represented by the following general formula (1) and the metal carboxyphthalocyanine compound represented by the following general formula (2) can be appropriately set. For example, the ratio (a) / (b) of the number of moles (a) of the metal aminophthalocyanine compound used and the number of moles (b) of the metal carboxyphthalocyanine compound used is 0.8 to 1. .2, preferably 0.9 to 1.1, more preferably 1. When triphenyl phosphite is used as the condensing agent, the amount of triphenyl phosphite used can be set as appropriate. The amount used is 2 to 40 mol, preferably 4 to 30 mol, more preferably 10 to 30 mol, and still more preferably 15 to 25 mol, with respect to 1 mol of the metal aminophthalocyanine compound represented by the following general formula (1). It can be illustrated. When triphenyl phosphite is used as the condensing agent, the amount of pyridine used can be appropriately set. The amount used is 6 to 120 mol, preferably 12 to 90 mol, more preferably 30 to 90 mol, and still more preferably 45 to 75 mol with respect to 1 mol of the metal aminophthalocyanine compound represented by the following general formula (1). It can be illustrated. Moreover, pyridine can be used also as a solvent irrespective of the usage-amount illustrated here. When triphenyl phosphite is used as the condensing agent, the amount of metal salt such as lithium chloride or calcium chloride can be appropriately set. As the usage-amount, the range of 0-50 mol with respect to 1 mol of metal aminophthalocyanine compounds shown by following General formula (1), Preferably it is 10-40 mol, More preferably, the range of 20-30 mol can be illustrated.

  Although the usage-amount of a solvent can be set suitably, as a usage-amount of a solvent, it is 0.5-100L (liter) with respect to 1 mol of metal aminophthalocyanine compounds shown by following General formula (1), Preferably it is 5 The range of -50L, More preferably, 10-30L can be illustrated. Although reaction temperature can be set suitably, as reaction temperature, it is 50-180 degreeC, for example, Preferably it is 80-150 degreeC, More preferably, it can be set as the range of 80-120 degreeC. Although reaction time can be set suitably, as reaction time, it can be set as 1 to 48 hours, for example, Preferably it is 1 to 24 hours, More preferably, it is 1 to 12 hours, More preferably, it can be 2 to 5 hours. . Examples of the condensation reaction include “Journal of Organic Chemistry Vol. 71, (2006) p. 2874-2877”, “Organic Letters Vol. 7, No. 9, (2005) p. 1737-1739”, “New Experiment”. Chemistry Lecture 14 Synthesis and Reaction of Organic Compounds II, pages 1136-1141 (1977), Maruzen Co., Ltd. ”can be referred to.

  The metal phthalocyanine polymer thus obtained has a repeating structural unit in which the structural unit represented by the general formula (1a) and the structural unit represented by the general formula (2a) are amide-bonded as described above. It is presumed to have a structure as shown in the general formula (7), that is, an amide structure.

(2) Manufacturing method of metal phthalocyanine polymer composite The metal phthalocyanine polymer composite can be manufactured by mixing a metal phthalocyanine polymer and a carbon material. The mixing step of the metal phthalocyanine polymer and the carbon material can include a method of mixing the carbon material into the synthesis system at any stage of the synthesis reaction in the above-described method for producing the metal phthalocyanine polymer. In the step of mixing the carbon material in the synthesis reaction, the metal phthalocyanine polymer of the general formula (7) is condensed from the metal aminophthalocyanine compound represented by the general formula (1) and the metal carboxyphthalocyanine compound represented by the general formula (2). The step of synthesis by reaction is particularly preferred. The mixing step can be performed using a known stirring device. The stirring temperature is not particularly limited as long as the condensation reaction proceeds, and is usually in the range of 50 to 150 ° C, and preferably in the range of 80 to 120 ° C. Further, the stirring time is not particularly limited as long as the condensation reaction proceeds, and is usually in the range of 1 to 100 hours, and preferably in the range of 10 to 50 hours.

  After completion of the condensation reaction, the product is transferred to a solvent such as dimethylformamide (DMF) or N-methylpyrrolidone (NMP), and stirred and filtered with suction within a range of 1 to 10 hours. After repeating this step a plurality of times, the product is extracted using a solvent by a known method and dried to obtain a metal phthalocyanine polymer composite.

  Further, the mixing step of the metal phthalocyanine polymer and the carbon material may be performed by separately manufacturing the metal phthalocyanine polymer (the compound of the general formula (7) above) and the carbon material, and then mixing both. This mixing step can also be performed using a known stirring device. The stirring temperature is usually in the range of 10 to 100 ° C, preferably in the range of 30 to 50 ° C. The stirring time is usually in the range of 10 minutes to 10 hours, preferably in the range of 1 to 5 hours.

3. Electrode Catalyst The electrode catalyst of the present invention (hereinafter simply referred to as “electrode catalyst”) can be obtained by using the metal phthalocyanine polymer composite as a precursor (manufacturing raw material) and calcining it by calcination. That is, the electrode catalyst is a fired product of the above metal phthalocyanine polymer composite. The electrode catalyst exhibits high oxygen reduction activity and can be suitably used as an electrode material for a fuel cell. Since the metal phthalocyanine polymer composite does not use platinum, an electrode catalyst obtained by carbonizing the metal phthalocyanine polymer composite does not contain platinum and is inexpensive. In addition, since the metal phthalocyanine polymer composite has a high carbon content and the phthalocyanine skeleton is regularly bonded, the resulting electrode catalyst also has a high carbon content and excellent metal dispersibility. Furthermore, since one metal L and the other metal M of the metal phthalocyanine polymer composite are different metals, it is possible to diversify the characteristics of the electrode catalyst by containing two kinds of metals in the electrode catalyst. This is useful when searching for an electrode catalyst having better characteristics.

The electrode catalyst used was a working electrode obtained by applying an electrode catalyst to a disk electrode, and the results obtained by performing linear sweep voltammetry under the following measurement conditions (same conditions as in Examples described later) were as follows (a) and (b). It is possible to have electrode characteristics that satisfy the following conditions.
<Measurement conditions>
-Electrolyte solution: 0.5 M sulfuric acid aqueous solution at oxygen saturation and nitrogen saturation-Auxiliary electrode: platinum plate-Reference electrode: Ag / AgCl electrode-Disk electrode rotation speed: 2000 rpm
-Sweep range: 950 mV to -400 mV
・ Sweep speed: 1mV / sec <electrode characteristics>
(A) Oxygen reduction starting potential (E ₀ ) at which the differential current value (I _diff ) is −1.0 × 10 ⁻⁶ A is 500 mV or more (b) The differential current value (I _{diff = 0} ) at a potential of 0 mV is − 2.0 × 10 ⁻⁴ A or less (here, the differential current value (I _diff ) is the current value (I _o2 ) when the electrolyte solution at oxygen saturation is measured and the electrolyte solution (I _N2 ) at nitrogen saturation) The difference (I _o2 −I _N2 ) from the current value when measuring

Here, in the present invention, the higher the value of the oxygen reduction start potential (E ₀ ) of the electrode characteristic (a) and the larger the value of the differential current value (I _{diff = 0} ) of the electrode characteristic (b) becomes negative. (In other words, the larger the absolute value), the higher the oxygen reduction activity. The oxygen reduction start potential (E ₀ ) indicates the potential when the oxygen reduction reaction starts, and the larger this value, the lower the reaction overvoltage of the electrode catalyst and the higher the activity as the electrode catalyst. Moreover, the value of the differential current value (I _{diff = 0} ) reflects the current density at a potential of 0 mV. The larger this value is, the faster the electron transfer rate per unit volume of the electrode catalyst, Means high activity.

As described above, the oxygen reduction starting potential (E ₀ ) of the electrode catalyst is 500 mV or more, preferably 550 mV, and more preferably 600 mV. Further, the differential current value (I _{diff = 0} ) of the electrode catalyst is −2.0 × 10 ⁻⁴ A or less, preferably −2.5 × 10 ⁻⁴ A or less, more preferably as described above. Is −3.0 × 10 ⁻⁴ A or less.

4). Method for Producing Electrocatalyst The method for producing the electrode catalyst of the present invention can be obtained by a step (firing step) in which the metal phthalocyanine polymer composite is fired to obtain a fired body. Furthermore, you may perform the process (acid treatment process) of acid-treating the obtained sintered body as needed.

(1) Firing step The fired body can be produced by firing a metal phthalocyanine polymer composite. The heating temperature at the time of firing is usually in the range of 650 to 1500 ° C, preferably in the range of 800 to 1000 ° C, more preferably in the range of 850 to 950 ° C. When the firing temperature is lower than 650 ° C., firing is insufficient and oxygen reduction activity is less likely to be exhibited. On the other hand, if the firing temperature is higher than 1500 ° C., the firing temperature is too high, so that the carbon structure is destroyed and the oxygen reduction activity is hardly exhibited, and the yield tends to decrease. The firing time is usually in the range of 0.1 to 12 hours, preferably in the range of 0.5 to 6 hours, more preferably in the range of 1 to 5 hours, and particularly preferably 2 Within the range of ~ 4 hours.

  Firing is preferably performed in a reducing gas atmosphere or an inert gas atmosphere. In particular, it is preferably performed in a reducing gas atmosphere because the metal can be reduced during the firing. Examples of the reducing gas include hydrogen, carbon monoxide, and hydrogen sulfide. Moreover, nitrogen, argon, etc. can be mentioned as an inert gas. The oxygen concentration in these gases is preferably 100 ppm or less, more preferably 20 ppm or less, and particularly preferably 10 ppm or less on a volume basis. Regarding firing, reference can be made to JP 2011-6283 A, JP 2009-57314 A, and the like.

(2) Acid treatment step After the above firing step (1), the fired product obtained as necessary is subjected to an acid treatment, so that at least a part of the metal contained in the fired product is eluted and the fired product. Remove from. By performing such an acid treatment step, at least a part of the metal contained in the fired body can be removed. Thereby, compared with the sintered body which does not remove a metal, there exists a tendency for the oxygen reduction activity of the obtained electrode catalyst to become high.

  In the acid treatment step, it is preferable to remove 0.01 to 100% by weight of metal by acid treatment. It is more preferable to remove 0.1 to 50% by weight of metal by acid treatment. More preferably, 1 to 25% by weight of metal is removed by acid treatment. More preferably, 3 to 20% by weight of metal is removed by acid treatment. It is particularly preferred to remove 5-15% by weight of metal by acid treatment. Therefore, the total amount of metals in the electrode catalyst is preferably in the range of 0 to 99.99% by weight, more preferably 50%, based on the total amount of metals contained in the metal phthalocyanine polymer composite before firing. Within the range of ˜99.9% by weight.

  The acid used in the acid treatment step is not particularly limited as long as it can elute metals and has low reactivity with carbon. For example, diluted hydrochloric acid, concentrated hydrochloric acid, diluted sulfuric acid, concentrated sulfuric acid, diluted nitric acid, concentrated nitric acid and At least one selected from the group consisting of aqua regia is preferred. These acids can be appropriately selected depending on the ionization tendency of the eluted metal. Of the above acids, aqua regia (concentrated nitric acid: concentrated hydrochloric acid = 1: 3 (volume ratio)) that has strong oxidizing power and ionizes by reacting with various metals is particularly preferable.

  When performing the acid treatment, it is preferable to pulverize the fired body. Further, during the acid treatment, it is preferable that ultrasonic treatment or the like is continuously performed so that the fired body is pulverized or dispersed in a solution. By performing treatment such as pulverization in this manner, elution of the metal by the acid is promoted, which is preferable.

  The acid treatment temperature is usually in the range of 0 to 80 ° C, preferably in the range of 2 to 70 ° C. The acid treatment time is usually in the range of 1 minute to 5 hours, preferably in the range of 10 minutes to 3 hours. Although the usage-amount of the acid of an acid treatment can be set suitably, as a usage-amount of an acid, it is 0.5-100L (liter) with respect to 1 kg of baked bodies, Preferably it exists in the range of 1-50L. For details of the acid treatment step, International Publication No. 2015/146858 can be referred to.

  The electrode catalyst of the present invention can be used for various applications as long as the characteristics can be exhibited. In particular, the electrode catalyst of the present invention can be used particularly suitably as a cathode of a fuel cell as described above. An electrode catalyst can be used as a catalyst-carrying electrode by coating on the surface of an electrode material such as glassy carbon. The electrode catalyst is preferably applied after being dispersed with ultrasonic waves in the presence of a solvent or a dispersant. The concentration of the dispersant is usually about 0.5 to 20% by weight, preferably about 1 to 10% by weight. The application method may be a method using a known apparatus such as a screen printing machine, a roll coater, or a gravure coater in addition to a method of simply dropping the dispersion solution. After coating, it is dried for several hours to several days at room temperature or high temperature.

  The reason why the electrode catalyst obtained by calcining the metal phthalocyanine polymer composite of the present invention has high oxygen reduction activity is not clear, but is presumed as follows. The oxygen reduction activity of the electrode catalyst depends on the carbon content and the metal dispersibility, and the higher the both, the higher the oxygen reduction activity. An electrode catalyst obtained by firing a metal phthalocyanine polymer originally has a high carbon content and excellent metal dispersibility. In addition, in the present invention, a carbon material containing carbon is blended in the metal phthalocyanine polymer. As a result, the electrode catalyst obtained by firing the metal phthalocyanine polymer composite has a higher carbon content and excellent oxygen reduction activity.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, these do not limit the objective of this invention.

1. Synthesis of tetranitrocobalt phthalocyanine (2) 4-nitrophthalic acid 5.02 g (23.7 mmol), ammonium heptamolybdate tetrahydrate 0.508 g (0.411 mmol), urea 15.0 g (0.250 mol), chloride Cobalt (II) 2.05 g (15.8 mmol) and nitrobenzene 75 mL were mixed, and this was stirred at 180 ° C. for 6 hours. The mixture after stirring was allowed to cool at room temperature and then filtered with suction, and the resulting solid was stirred overnight with methanol to obtain a reaction product. Thereafter, 360 mL of 1M hydrochloric acid prepared by adding saturated brine to hydrochloric acid was added to the reaction product, boiled, and filtered with suction. This operation was repeated twice. Thereafter, 350 mL of pure water was added to the obtained reaction product, boiled, and suction filtered. This operation was also repeated twice as described above. The obtained solid was dried under reduced pressure at 80 ° C. to obtain a black solid tetranitrocobalt phthalocyanine (2) in a yield of 3.62 g and a yield of 70%. The structure was confirmed by FT-IR.

<Structure confirmation by FT-IR>
FIG. 2 shows the IR spectrum of tetranitrocobalt phthalocyanine (2). Peaks attributed to nitro groups were observed in the vicinity of 1520 cm ⁻¹ and 1330 cm ⁻¹ .

2. Synthesis of tetraaminocobalt phthalocyanine (M1) In an argon atmosphere, 3.74 g (4.27 mmol) of tetranitrocobalt phthalocyanine (2) and 55 mL of pure water were added, stirred for 1 hour at room temperature, and then sodium sulfide dissolved in 51 mL of pure water. 20.5 g (0.263 mol) of nonahydrate was mixed and further stirred for 1 hour. Thereafter, the stirred mixture was further stirred at 65 ° C. for 8 hours to obtain a reaction product. The resulting reaction product was allowed to cool at room temperature and then filtered with suction. Next, the filtered reaction product was washed with pure water and methanol, and then filtered with suction, and the resulting solid was once dried under reduced pressure. Thereafter, 400 mL of 0.1 M dilute hydrochloric acid prepared by adding pure water to hydrochloric acid was prepared, and the resulting solid was dissolved, and the solution was neutralized with an aqueous KOH solution until pH = 8, and boiled. . The solution after boiling was allowed to cool at room temperature, and the precipitated solid was filtered with suction. The collected solid was dried under reduced pressure at 80 ° C. to obtain a black solid tetraaminocobalt phthalocyanine (M1) in a yield of 1.34 g and a yield of 41%. The structure was confirmed by FT-IR and UV-vis.

<Structure confirmation by FT-IR>
FIG. 3A shows an IR spectrum of tetraaminocobalt phthalocyanine (M1). 1520 cm ^-1, disappeared peaks derived from the nitro group was observed in the vicinity of 1330cm ^-1, 3330cm ^-1, observed peaks due to a cyano group and an amino group near 3200 cm ^-1 amino group, in the vicinity of 1600 cm ^-1 did.

<Structure confirmation by UV-vis>
FIG. 3B shows an ultraviolet absorption spectrum of tetraaminocobalt phthalocyanine (M1). A peak due to the phthalocyanine skeleton was observed in the vicinity of 650 to 700 nm. Table 1 shows the maximum absorption amount and the wavelength at the shoulder peak of the ultraviolet absorption spectrum.

Table: UV-vis of Tetraaminocobalt(II) phthalocyanine

Table: UV-vis of Tetraaminocobalt (II) phthalocyanine

3. Synthesis of tetracarboxyamido cobalt phthalocyanine (4) 10.2 g (52.8 mmol) trimellitic anhydride, 1.05 g (0.850 mmol) ammonium molybdate, 15.0 g (0.250 mol) urea, cobalt (II) chloride 4.44 g (34.2 mmol) and 75 mL of nitrobenzene were mixed, and this was stirred at 180 ° C. for 6 hours. The mixture after stirring was allowed to cool, then filtered with suction and washed with methanol. To the solid obtained by suction filtration, 360 mL of 1M hydrochloric acid prepared by adding saturated brine to hydrochloric acid was boiled, and filtered with suction using pure water and methanol. This operation was repeated twice. Then, the solid obtained by suction filtration was boiled using 350 mL of pure water, and suction filtered with pure water. This operation was also performed twice as described above. The obtained solid was dried at 80 ° C. under reduced pressure to obtain a dark blue solid tetracarboxyamido cobalt phthalocyanine (4) in a yield of 9.12 g and a yield of 79%. The structure was confirmed by FT-IR.

<Structure confirmation by FT-IR>
FIG. 4 shows an IR spectrum of tetracarboxyamido cobalt phthalocyanine (4). 3350 cm ^-1, 3200 cm ^-1-amino group near were observed peaks attributed to carbonyl group and carboxamide group near 1650 cm ^-1.

4). Synthesis of tetracarboxycobalt phthalocyanine (M2) 3.61 g (4.14 mmol) of tetracarboxyamido cobalt phthalocyanine (4), 38.3 g (0.682 mol) of potassium hydroxide, and 38 mL of pure water were mixed, and this was mixed at 100 ° C. Stir for 24 hours. The mixture after stirring was allowed to cool at room temperature, hydrochloric acid was added to 100 mL of pure water to adjust to pH = 2, and the mixture was left to crystallize for 3 days. The crystals were filtered by suction and washed with pure water, ethanol and diethyl ether, and then the remaining solid was dried at 80 ° C. under reduced pressure to give 3.33 g, 92% yield of tetracarboxycobalt phthalocyanine (M2) as a dark purple solid. I got it. The structure was confirmed by FT-IR and UV-vis.

<Structure confirmation by FT-IR>
FIG. 5A shows the IR spectrum of tetracarboxycobalt phthalocyanine (M2). The peaks attributed to the carboxamide group observed in the vicinity of 3350 cm ⁻¹ , 3200 cm ⁻¹ , and 1650 cm ⁻¹ disappeared, and the peak attributed to the carboxy group was observed in the vicinity of 1700 cm ⁻¹ .

<Structure confirmation by FT-IR>
FIG. 5B shows an ultraviolet absorption spectrum of tetracarboxycobalt phthalocyanine (M2). A peak due to the phthalocyanine skeleton was observed in the vicinity of 650 to 700 nm. Table 2 shows the maximum absorption amount and the wavelength at the shoulder peak of the ultraviolet absorption spectrum.

Table: UV-vis of Tetracarboxycobalt(II) phthalocyanine

Table: UV-vis of Tetracarboxycobalt (II) phthalocyanine

5). Synthesis of Cobalt Phthalocyanine Complex (P1 [Co-Co]): Comparative Example 1
Under argon atmosphere, tetraaminocobalt phthalocyanine (M1) 0.632 g (1.00 mmol), tetracarboxycobalt phthalocyanine (M2) 0.744 g (0.995 mmol), DMF 50 mL, pyridine 12.5 mL, triphenyl phosphite 6.5 mL and 1.52 g of lithium chloride were added to obtain a mixture. The mixture was stirred at 100 ° C. for 24 hours for reaction. After completion of the reaction, the product was transferred into DMF, stirred for 3 hours and filtered with suction. This operation was repeated three times. Then, Soxhlet extraction was performed for 24 hours each using methanol and THF. Then, it dried under reduced pressure at 80 degreeC for 6 hours, and obtained P1 [Co-Co] of black powder with a yield of 0.758g and a yield of 56%. The structure was confirmed by FT-IR.

6). Synthesis of Carbon Black-containing Cobalt Phthalocyanine Complex (P1 [Co-Co] + CB (2: 1)): Example 1
Under argon atmosphere, tetraaminocobalt phthalocyanine (M1) 0.694 g (1.10 mmol), tetracarboxycobalt cobalt phthalocyanine (M2) 0.734 g (0.98 mmol), DMF 50 mL, pyridine 12.5 mL, triphenyl phosphite 6.5 mL, 1.52 g of lithium chloride, and 0.714 g of carbon black (Ketjen Black EC600JD: manufactured by Lion Corporation) were added (weight ratio 2: 1 with respect to the total of M1 and M2) to obtain a mixture. The mixture was stirred at 100 ° C. for 24 hours for reaction. After completion of the reaction, the product was transferred into DMF, stirred for 3 hours and filtered with suction. This operation was repeated three times. Then, Soxhlet extraction was performed for 24 hours each using methanol and THF. Then, it dried under reduced pressure at 80 degreeC for 6 hours, and obtained black powder P1 [Co-Co] + CB (2: 1) with a yield of 1.52g and a yield of 92%. The structure was confirmed by FT-IR.

<Structure confirmation by FT-IR>
FIG. 6 shows an IR spectrum of a carbon black-containing cobalt phthalocyanine complex (P1 [Co—Co] + CB (2: 1)). 3400 cm ^-1-amino group near were observed peaks attributed to one substituted amide carbonyl group near 1650 cm ^-1.

7). Synthesis of carbon black-containing cobalt phthalocyanine complex (P1 + CB (10: 1)): Example 2
Under an argon atmosphere, Tetraaminocobalt (II) phthalocyanine (M1) 0.696 g (1.10 mmol), Tetracaboxycobalt (II) phthalocyanine (M2) 0.747 g (1.00 mmol), DMF 60 mL, pyridine 7.5 mL, phosphorous acid Add 6.5 mL of triphenyl, 1.53 g of lithium chloride, and 0.144 g of carbon black (Ketjen Black ECP-600: manufactured by Lion Corporation) (weight ratio 10: 1 with respect to the total of M1 and M2). Obtained. The mixture was stirred at 100 ° C. for 24 hours for reaction. After completion of the reaction, the product was transferred into DMF, stirred for 3 hours and filtered with suction. This operation was repeated three times. Then, Soxhlet extraction was performed for 24 hours each using methanol and THF. Then, it dried under reduced pressure at 80 degreeC for 6 hours, and obtained P1 [Co-Co] + CB (10: 1) of black powder by the yield 1.29g and the yield 76%. The structure was confirmed by FT-IR.

<Structure confirmation by FT-IR>
FIG. 7 shows an IR spectrum of a carbon black-containing cobalt phthalocyanine complex (P1 + CB (10: 1)). 3400 cm ^-1-amino group near were observed peaks attributed to one substituted amide carbonyl group near 1650 cm ^-1.

8). Synthesis of carbon black-containing cobalt phthalocyanine complex (P1 + CB (20: 1)): Example 3
Under argon atmosphere, Tetraaminocobalt (II) Phthalocyanine (M1) 0.701 g (1.10 mmol), Tetracaboxycobalt (II) Phthalocyanine (M2) 0.755 g (1.00 mmol), DMF 60 mL, pyridine 7.5 mL, phosphorous acid 6.5 mL of triphenyl, 1.53 g of lithium chloride, and 0.0728 g of carbon black (Ketjen Black ECP-600: manufactured by Lion Corporation) were added (weight ratio of 20: 1 with respect to the total of M1 and M2). Obtained. The mixture was stirred at 100 ° C. for 24 hours for reaction. After completion of the reaction, the product was transferred into DMF, stirred for 3 hours and filtered with suction. This operation was repeated three times. Then, Soxhlet extraction was performed for 24 hours each using methanol and THF. Then, it dried under reduced pressure at 80 degreeC for 6 hours, and obtained P1 [Co-Co] + CB (20: 1) of black powder with the yield of 0.819g and 59% of the yield. The structure was confirmed by FT-IR.

<Structure confirmation by FT-IR>
FIG. 8 shows an IR spectrum of a carbon black-containing cobalt phthalocyanine complex (P1 + CB (20: 1)). 3400 cm ^-1-amino group near were observed peaks attributed to one substituted amide carbonyl group near 1650 cm ^-1.

9. Synthesis of carbon black-containing cobalt phthalocyanine complex (P1 + CB (30: 1)): Comparative Example 2
Under an argon atmosphere, Tetraaminocobalt (II) phthalocyanine 0.632 g (1.00 mmol), Tetracaboxylate (II) phthalocyanine 0.748 g (1.00 mmol), DMF 50 mL, pyridine 7.5 mL, triphenyl phosphite 4.7 mL, lithium chloride 1.53 g and 0.0460 g of carbon black (Ketjen Black ECP-600: manufactured by Lion Corporation) were added (weight ratio 30: 1 with respect to the total of M1 and M2) to obtain a mixture. This mixture was stirred at 100 ° C. for 24 hours to carry out a reaction. After completion of the reaction, the product was transferred into DMF, stirred for 3 hours and filtered with suction. This operation was repeated three times. Then, Soxhlet extraction was performed for 24 hours each using methanol and THF. Then, it dried under reduced pressure at 80 degreeC for 6 hours, and obtained P1 + CB [Co-Co] (30: 1) of black powder with a yield of 1.33g and a yield of 93%. The structure was confirmed by FT-IR.

<Structure confirmation by FT-IR>
FIG. 9 shows an IR spectrum of a carbon black-containing cobalt phthalocyanine complex (P1 + CB (30: 1)). 3400 cm ^-1-amino group near were observed peaks attributed to one substituted amide carbonyl group near 1650 cm ^-1.

10. Firing of each synthesized sample In a trifurcated glass tube, quartz wool, P1 [Co-Co], and each P1 [Co-Co] + CB having different carbon black contents are packed into a ceramic electric tubular furnace (ARF-30KC). It was set and left in a nitrogen stream for 1 hour to make it inert. Thereafter, the temperature was raised to 900 ° C., calcination was performed in a hydrogen stream for 3 hours, and carbonized to obtain a catalyst material. After the completion of firing, the mixture was allowed to cool to room temperature in a nitrogen stream, and a black residue was recovered. The firing results for each sample are shown in Table 3 below.

10. LSV Measurement In order to evaluate the oxygen reduction activity of the obtained catalyst material, linear sweep voltammetry measurement (LSV) using a rotating disk voltammetry device (RRDE-3A ver. 1.2 manufactured by BAS Inc.). Measurement). For sample preparation, 5 mg of a catalyst material pulverized to a particle size of 30 μm or less was dispersed in 50 μL of 5% Nafion dispersion solution, 150 μL of ethanol, and 150 μL of pure water to prepare an ink solution.

An ink solution of 1 μL was applied onto a 3 mm inner diameter glassy carbon (GC) disk electrode and dried to obtain an oxygen reduction electrode. A 0.5 M sulfuric acid aqueous solution was used as the electrolytic solution, and an oxygen saturated sulfuric acid aqueous solution saturated by bubbling oxygen in advance and a nitrogen saturated sulfuric acid aqueous solution from which oxygen was removed by bubbling nitrogen were prepared. A platinum plate was used as the auxiliary electrode, and an Ag / AgCl electrode was used as the reference electrode. The LSV measurement was performed using the above electrode and the electrolyte, at an electrode rotation speed of 2000 rpm, a sweep range of 950 mV to -400 mV, and a sweep speed of 1 mV / s. Each of the electrolyte solution at the time of oxygen saturation and the electrolyte solution at the time of nitrogen saturation was measured, and the oxygen reduction activity was evaluated from the difference (I _diff ) between the obtained current values.

FIG. 1 shows a voltammogram of platinum catalyst after calcination of P1 [Co—Co] and P1 [Co—Co] + CB having different carbon black contents. From the results shown in this figure, when carbon black was added so as to have a predetermined content as in Examples 1 to 3, the oxygen reduction starting potential was as high as 500 mV or more, and the differential current value (I _{diff at a} potential of 0 mV). _{= 0} ) is −2.0 × 10 ⁻⁴ A or less, indicating that the oxygen reduction activity is high. On the other hand, in Comparative Example 1 that does not contain carbon black and Comparative Example 2 in which the content of carbon black is low, the oxygen reduction starting potential is lower than in Examples 1 to 3, and the differential current value (I _{diff = 0).} ) Was high, it was found that the oxygen reduction activity was low compared to these Examples.

11. Aqua regia treatment The metal was removed by aqua regia treatment in which 0.3 g of the catalyst material of Example 1 was dissolved in 2.5 mL of aqua regia. After filtration, washing, and drying, an ink solution was similarly prepared, LSV measurement was performed, and the activity of the demetallized catalyst from which the metal was removed was evaluated.

In FIG. 10, the voltammogram after baking of P1 [Co-Co] of Example 1 and after aqua regia treatment is shown. From the result of this figure, the value of the oxygen reduction starting potential was almost the same before and after the aqua regia treatment, but the difference current value (I _{diff = 0} ) at the potential of 0 mV was superior after the aqua regia treatment. From this, it was found that oxygen reduction activity was increased by aqua regia treatment.

Claims (13)

A metal phthalocyanine polymer having a repeating structural unit in which a structural unit represented by the general formula (1a) and a structural unit represented by the general formula (2a) are amide-bonded, and a carbon material, the metal phthalocyanine polymer The metal phthalocyanine polymer composite is characterized in that the blending ratio of the carbon material and the carbon material is in the range of 1: 1 to 25: 1 on a weight basis.

(In general formula (1a), L is a divalent or trivalent metal ion belonging to the third to fifth periods of the long-period periodic table.)

(In general formula (2a), M is a divalent or trivalent metal ion belonging to the third to fifth periods of the long-period periodic table.) 2. The metal phthalocyanine polymer composite according to claim 1, wherein L and M are each independently a metal ion selected from the group consisting of Co ²⁺ , Ni ²⁺ , and Fe ²⁺ . The metal phthalocyanine polymer composite according to claim 1, wherein L and M are Co ²⁺ . The metal phthalocyanine polymer composite according to claim 1, wherein L is Co ²⁺ and M is Ni ²⁺ . The metal phthalocyanine polymer composite according to claim 1, wherein L is Co ²⁺ and M is Fe ²⁺ .   The metal phthalocyanine polymer composite according to claim 1, wherein the carbon material is carbon black. An electrode catalyst comprising a fired product of the metal phthalocyanine polymer composite according to claim 1,
In linear sweep voltammetry using a working electrode in which the electrode catalyst is applied to a disk electrode, 0.5M sulfuric acid aqueous solution at the time of oxygen saturation and nitrogen saturation as an electrolyte, a platinum plate as an auxiliary electrode, and an Ag / AgCl electrode as a reference electrode Used, the electrolyte solution at the time of oxygen saturation and the electrolyte solution at the time of nitrogen saturation were swept from a sweep range of 950 mV to −400 mV at a sweep speed of 1 mV / sec under the condition of a rotational speed of the disk electrode of 2000 rpm. An electrode catalyst characterized by having electrode characteristics that satisfy the following conditions (a) and (b).
<Electrode characteristics>
When the current value of the difference between the current value when measuring the electrolytic solution at the time of oxygen saturation and the current value when measuring the electrolytic solution at the time of nitrogen saturation is the differential current value (I _diff ),
(A) The oxygen reduction starting potential (E ₀ ) at which the differential current value (I _diff ) is −1.0 × 10 ⁻⁶ A is 500 mV or more,
(B) The differential current value (I _{diff = 0} ) at a potential of 0 mV is −2.0 × 10 ⁻⁴ A or less.   An electrode catalyst produced by firing the metal phthalocyanine polymer composite according to claim 1 at 650 to 1500 ° C in a reducing gas atmosphere or an inert gas atmosphere.   A method for producing an electrode catalyst, comprising producing the metal phthalocyanine polymer composite according to claim 1 by firing at 650 to 1500 ° C in a reducing gas atmosphere or in an inert gas atmosphere.   The method for producing an electrode catalyst according to claim 9, wherein the calcination is performed at 800 to 1000 ° C. in a reducing gas atmosphere.   The method for producing an electrode catalyst according to claim 9, wherein the metal phthalocyanine polymer composite after calcination is further acid-treated.   The method for producing an electrode catalyst according to claim 11, wherein the acid is at least one selected from the group consisting of dilute hydrochloric acid, concentrated hydrochloric acid, dilute sulfuric acid, concentrated sulfuric acid, dilute nitric acid, concentrated nitric acid, and aqua regia. .   The method for producing an electrocatalyst according to claim 12, wherein the acid is aqua regia.

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