JP6993640B2 - Nitrogen-containing polycyclic compound - Google Patents

Description

The present invention relates to nitrogen-containing polycyclic compounds. More specifically, the present invention relates to a nitrogen-containing polycyclic compound that can be suitably used as an oxygen reduction catalyst, a fired body thereof, and an oxygen reduction catalyst composed of the nitrogen-containing polycyclic compound or a fired body.

Graphene nanoribbon (GNR) has a graphene-like structure in which carbon atoms bonded by sp ² bonds are arranged on a plane, but it is not a two-dimensional plane, but a linear type like a ribbon or an armchair type. Has a shape. Due to its unique structure and physical properties, GNR has been studied extensively and is expected to be used in various applications. For example, unlike planar graphene, GNR has a finite minor axis direction and has a band gap, so that it is expected to be used as a semiconductor.

There are roughly two methods for synthesizing such GNR. The first is a method of opening carbon nanotubes in the axial direction, and for example, a method of opening a ring of carbon nanotubes with an oxidizing agent is disclosed (see, for example, Non-Patent Document 1). The second is a method using a method of organic synthesis. As for the method using the organic synthesis method, the precursor can be obtained by using the organic synthesis method, and the GNR conversion of the precursor uses the thermal (physical) action, and all the organic synthesis methods up to GNR can be used. There is something to be gained by using it. As the former, for example, up to the bromo form as a precursor is synthesized by an organic synthesis method, and polymerization and GNR formation are performed by heating on a substrate to obtain a linear GNR and an armchair type GNR, and scanning is performed. Those identified using a type tunneling microscope are disclosed (see, for example, Non-Patent Document 2). As the latter, for example, an armchair-type nitrogen-containing GNR obtained by an organic synthesis method is disclosed (see, for example, Non-Patent Document 3).

By the way, an example in which a nitrogen-containing nanocarbon material and a metal such as iron are mixed and used as an oxygen reduction catalyst is disclosed (see, for example, Non-Patent Document 4).

Dmitry V. Kosynkin, 6 others, Nature 458, 872-876 (2009) Jinming Cai, 11 others, Nature 466, 470-473 (2010) Timothy H. Vo, 6 others, Chem. Commun., 2014, 50, 4172-4174 Zimmermann G, 2 others, Top Curr. Chem., 1976, 61, 133-181

As mentioned above, it is considered to use GNR for various purposes, but GNR has various widths such as different widths, linear type, armchair type, and doped with other elements. It can be said that the structure of the above is considered, and it cannot be said that the study has been sufficiently advanced, and there is room for further development of GNR. It is preferable to develop a GNR having a new structure in order to consider the development into various applications in the future.

The present invention has been made in view of the above situation, and an object of the present invention is to provide a novel GNR.

The present inventors have studied various novel GNRs and synthesized nitrogen-containing polycyclic compounds having a nitrogen-containing GNR in which the position of nitrogen was specified. The present inventors have found that a product obtained by calcining and supporting a metal with this nitrogen-containing polycyclic compound has excellent oxygen reduction reaction activity and is useful as a raw material for an oxygen reduction catalyst, and solves the above-mentioned problems brilliantly. I came up with the idea of being able to do this, and arrived at the present invention.

That is, the present invention is a nitrogen-containing polycyclic compound characterized by having a structural unit containing a structure represented by the following general formula (1).

(In the formula, X ¹ and X ² are hydrogen atom, halogen atom, OTf group, OTs group, respectively, or a structure other than the structure represented by the general formula (1) in the structural unit or another structure. Tf represents a trifluoromethylsulfonyl group and Ts represents a tosyl group. Y1, Y2, ^Y7 , and ^{Y8 are each} bonded to a hydrogen atom. Represents a carbon atom or a carbon atom bonded to a structure other than the structure represented by the general formula ^{( 1} ) in the structural unit or another structural unit. Y3 and Y4, ^Y5 and ^Y6 are , One represents a nitrogen atom and the other represents a carbon atom bonded to a hydrogen atom. The dotted line indicates that the bond may or may not be formed.)
The present invention will be described in detail below.

The nitrogen-containing polycyclic compound of the present invention has the above-mentioned structure, and a highly active oxygen reduction catalyst using the nitrogen-containing polycyclic compound of the present invention can be obtained.

The results of measuring MALDI-TOFMS for the nitrogen-containing polycyclic compound of the present invention are shown. The results of measuring ICP-AES (inductively coupled plasma emission spectroscopic analysis) and elemental analysis on the nitrogen-containing polycyclic compound and the calcined product of the present invention are shown. The results of thermogravimetric measurement of the nitrogen-containing polycyclic compound of the present invention are shown. The result of performing X-ray photoelectron spectroscopy on the nitrogen-containing polycyclic compound of this invention is shown. The result of performing X-ray photoelectron spectroscopy on the fired body of this invention is shown. The result of having analyzed the X-ray absorption fine structure about the fired body of this invention is shown. The result of having analyzed the X-ray absorption fine structure about the fired body of this invention is shown. The oxygen reduction reaction activity of the fired body of the present invention is shown. The oxygen reduction reaction activity of the fired body of the present invention and the fired body of the comparative example is shown.

The present invention will be described in detail below.
It should be noted that a combination of two or more of the individual preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.

<Nitrogen-containing polycyclic compound>
The nitrogen-containing polycyclic compound of the present invention has a structural unit containing the structure represented by the above general formula (1). The nitrogen-containing polycyclic compound of the present invention has a structural unit containing the structure represented by the general formula (1), even if the structural unit has a structure represented by the general formula (1). Often, the structure represented by the general formula (1) may be added with another structure other than the structure represented by the general formula (1).
The structure other than the structure represented by the general formula (1) is an atom or an atomic group bonded to the structure represented by the general formula (1), and is represented by the general formula (1). The above-mentioned structural unit is configured together with the structure to be formed. As the atom or atomic group bonded to the structure represented by the general formula (1), a carbon atom bonded by an sp ² bond constituting a structure arranged on a plane is preferable, but nitrogen, oxygen, sulfur, and the like. It may be doped with a different element such as silicon or phosphorus.

The number of the above-mentioned structural units contained in the nitrogen-containing polycyclic compound of the present invention may be one, or two or more may be linked. That is, the nitrogen-containing polycyclic compound of the present invention may be a nitrogen-containing GNR or a monomer or a polymer which is a raw material of the nitrogen-containing GNR.
The nitrogen-containing polycyclic compound of the present invention can freely extend the conjugated system by GNR conversion, thereby expanding the conductive path and making the oxygen reduction reaction activity more excellent. Conceivable. Further, the GNR and the monomer or polymer which is a raw material thereof have an edge basically composed of a so-called armchair edge and are stable to oxygen.

In the above general formula (1), Y ³ and Y ⁴ , Y ⁵ and Y ⁶ each represent a nitrogen atom and the other represents a carbon atom bonded to a hydrogen atom. In other words, one of Y ³ and Y ⁴ represents a nitrogen atom and the other represents a carbon atom bonded to a hydrogen atom, and one of Y ⁵ and Y ⁶ represents a nitrogen atom and the other represents a hydrogen atom. Represents a carbon atom.
Of these, it is preferable that Y ³ and Y ⁶ each represent a carbon atom bonded to a hydrogen atom, and Y ⁴ and Y ⁵ each represent a nitrogen atom. This makes it possible to chelate the metal element, and the oxygen reduction reaction activity becomes more excellent in the oxygen reduction catalyst.
When a nitrogen-containing polycyclic compound of the present invention is obtained by forming a bond on at least the upper three dotted lines in the general formula (1), Y ³ and Y ⁴ , Y ⁵ and Y ⁶ are obtained between the constituent units. In some cases, a mixture of monomers or a polymer in which the above is reversed can be obtained. In such a form as well, a part of the structural unit represents a carbon atom in which Y ³ and Y ⁶ are bonded to a hydrogen atom, respectively, and Y ⁴ and Y ⁵ represent a nitrogen atom, respectively. Therefore, in the present invention. It is one of the preferred forms.

In the above general formula (1), the halogen atom represented by X ¹ and X ² is preferably a chlorine atom or a bromine atom, and more preferably a bromine atom.

In the general formula (1), X ¹ and X ² each represent a structure other than the structure represented by the general formula (1) in the above structural unit or a binding site with another structural unit, and are Y. ¹ , Y ² , Y ⁷ and Y ⁸ may each represent a carbon atom bonded to another structure or other structural unit other than the structure represented by the general formula (1) in the above structural units. It is one of the preferred forms in the present invention. As a result, the nitrogen-containing polycyclic compound becomes an armchair-type nitrogen-containing GNR.

When the nitrogen-containing polycyclic compound of the present invention is a monomer which is a raw material of nitrogen-containing GNR, for example, the monomer represented by the following general formula (2) is preferable.

In the above general formula (2), X ¹ and X ² represent a hydrogen atom, a halogen atom, an OTf group, an OTs group, an alkyl group, or an aryl group, respectively, and Tf represents a trifluoromethylsulfonyl group. Ts represents a tosyl group. Y ³ and Y ⁴ , Y ⁵ and Y ⁶ each represent a nitrogen atom and the other a carbon atom bonded to a hydrogen atom. The dotted line indicates that the bond may or may not be formed.

When X ¹ and X ² are leaving groups such as a halogen atom, an OTf group, or an OTs group, an alkyl group or an aryl group is added to these by a reaction such as Suzuki coupling, Negishi coupling, or still coupling. It is also possible to introduce it. These forms are also preferred forms of the present invention.

When the nitrogen-containing polycyclic compound of the present invention is a polymer which is a raw material of nitrogen-containing GNR, for example, the polymer represented by the following general formula (3) is preferable.

In the above general formula (3), X ¹ and X ² represent a hydrogen atom, a halogen atom, an OTf group, an OTs group, an alkyl group, or an aryl group, respectively, and Tf represents a trifluoromethylsulfonyl group. Ts represents a tosyl group. Y ³ and Y ⁴ , Y ⁵ and Y ⁶ each represent a nitrogen atom and the other a carbon atom bonded to a hydrogen atom. The dotted line indicates that the bond may or may not be formed. n is a number of 1 or more, and is usually 1000 or less.

When X ¹ and X ² are leaving groups such as a halogen atom, an OTf group, or an OTs group, an alkyl group or an aryl group is added to these by a reaction such as Suzuki coupling, Negishi coupling, or still coupling. It is also possible to introduce it. By introducing these functional groups, the influence of the terminal functional groups on the physical characteristics can be reduced. These forms are also preferred forms of the present invention.

When the nitrogen-containing polycyclic compound of the present invention is a nitrogen-containing GNR, the nitrogen-containing GNR is preferably an armchair type, for example, a nitrogen-containing GNR having a skeleton represented by the following general formula (4). It is preferable to have.

In the general formula (4), Y ³ and Y ⁴ , Y ⁵ and Y ⁶ are the same as those described above in the formula (3), respectively. n is a number of 1 or more, and is usually 1000 or less.
In the present specification, the nitrogen-containing GNR having a skeleton represented by the above general formula (4) may be simplified and expressed by the following general formula (5).

In the above general formula (5), n is a number of 1 or more, and is usually 1000 or less.
The above-mentioned nitrogen-containing GNR, its raw material monomer, and raw material polymer can be obtained by using, for example, a reaction represented by the following reaction formula.

In the above reaction formula, X represents a hydrogen atom or a halogen atom. The halogen atom is preferably, for example, a bromine atom. The obtained product is a raw material monomer of nitrogen-containing GNR, and the one in which X represents a hydrogen atom is also referred to as PPyTP (1,4-diPhenyl-2,3-diPyridylTriPhenyllene) in the present specification.

In the above reaction formula, X represents a halogen atom. The halogen atom is preferably, for example, a bromine atom. One of Y ³ and Y ⁴ represents a nitrogen atom, and the other represents a carbon atom bonded to a hydrogen atom. One of Y ⁵ and Y ⁶ represents a nitrogen atom, and the other represents a carbon atom bonded to a hydrogen atom. n and p are numbers of 1 or more, respectively, and are usually 1000 or less. [PPyTP] _n is a raw material polymer of nitrogen-containing GNR, and BPy-GNR is nitrogen-containing GNR.
In the reaction represented by the above reaction formula, the reaction temperature and the reaction time can be appropriately set.

The nitrogen-containing polycyclic compound of the present invention preferably further contains at least one element selected from the metal elements belonging to the 7th to 11th groups of the periodic table, which are carried on the above-mentioned structural units. A nitrogen-containing polycyclic compound carrying a metal element in this way can also be referred to as a metal complex. Thereby, the oxygen reduction reaction activity as an oxygen reduction catalyst can be made more excellent. The element may be in the atomic state or may be a cation. It may also be in the form of clusters or particles.
Among the metal elements belonging to the 7th to 11th groups in the periodic table, the metal elements belonging to the 8th to 11th groups are preferable, and Fe, Co, Ni and Cu are more preferable.
Further, it is preferable that the metal element is coordinated with the nitrogen atom in the structure represented by the general formula (1) described above, and among them, Y ⁴ and Y ⁵ in the formula (1) each represent a nitrogen atom. It is more preferable that a metal element is coordinated with the nitrogen atom. As a result, the metal element is chelated and stabilized, and the effect of the present invention becomes more remarkable.
The coordination of the metal element to the nitrogen atom can be measured by the method of the example using X-ray photoelectron spectroscopy and wide area X-ray absorption fine structure analysis method (EXAFS method).

The content of the metal element is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and 0.5% by mass in 100% by mass of the nitrogen-containing polycyclic compound of the present invention. % Or more is more preferable. The content is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 3% by mass or less.
The content of the metal element can be measured by the method of Examples by inductively coupled plasma emission spectroscopy (ICP-AES method).

By mixing the above-mentioned nitrogen-containing GNR, its raw material monomer, and raw material polymer with a compound having a metal element and heating or the like, the nitrogen-containing polycycle of the present invention having the above-mentioned metal element is carried in the above-mentioned structural unit. The formula compound can be obtained. Preferred conditions such as heating temperature and time for supporting the metal are the same as preferable conditions for firing described later. Further, as described later, metal support and firing may be performed at the same time.
As the compound having a metal element used for mixing, for example, a halide of the metal element is preferable.

(Fired body)
The present invention is also a calcined product of the nitrogen-containing polycyclic compound of the present invention.
The fired body of the present invention is obtained by firing a nitrogen-containing GNR, a raw material monomer or a raw material polymer thereof, or a metal carrier (metal composite) thereof, which is a nitrogen-containing polycyclic compound of the present invention. Above all, it is preferably obtained by firing together with a carbon material. In the present specification, firing the nitrogen-containing polycyclic compound of the present invention together with a carbon material is also referred to as carbonization.
In order to obtain the calcined product of the present invention on which the metal element is supported and carbonized, the support of the metal element and the carbonization may or may not be simultaneous. When the support of the metal element and the carbonization are not performed at the same time, the period before and after the metal element is not particularly limited, and the carbonization may be performed after the metal element is supported, or the metal element may be supported after the carbonization. ..
Above all, from the viewpoint of convenience, it is particularly preferable that the support of the metal element and the carbonization are performed at the same time. That is, it is particularly preferable to calcin the above-mentioned nitrogen-containing GNR or its raw material monomer or raw material polymer together with a compound having a carbon material and a metal element.
The nitrogen-containing polycyclic compound and calcined product of the present invention have more excellent activity as an oxygen reduction catalyst by supporting the above metal element.

The carbon material is not particularly limited, but activated carbon, carbon black and the like can be used, and for example, conductive carbon black such as Vulcan XC-72R (manufactured by Cabot Corporation) can be preferably used.
The amount of the carbon material used is, for example, preferably 1 to 1000% by mass, more preferably 5 to 500% by mass, and 10 to 300% with respect to 100% by mass of the nitrogen-containing polycyclic compound of the present invention. It is more preferably mass%, and particularly preferably 30 to 200 mass%.

The firing temperature is, for example, preferably 200 to 3000 ° C, more preferably 350 to 2500 ° C, and even more preferably 500 to 2000 ° C.
The firing time is preferably, for example, 10 minutes to 24 hours, more preferably 30 minutes to 18 hours, and even more preferably 2 to 12 hours.
The calcination can be carried out, for example, in the air or in an atmosphere of an inert gas such as nitrogen, helium or argon. Further, the pressure conditions in firing are not particularly limited, and the firing can be performed under pressurized conditions, normal pressure conditions, and reduced pressure conditions.
Before firing, pre-baking may be performed at a temperature equal to or lower than the firing temperature. After firing, pickling, washing with water, drying and the like can be appropriately performed.

(Oxygen reduction catalyst)
The present invention is also an oxygen reduction catalyst comprising the nitrogen-containing polycyclic compound of the present invention or the calcined product of the present invention.

The oxygen reduction catalyst of the present invention may contain the nitrogen-containing polycyclic compound of the present invention or other components other than the calcined product of the present invention. The content ratio of other components is preferably 30% by mass or less, more preferably 10% by mass or less, still more preferably 1% by mass or less, based on 100% by mass of the oxygen reduction catalyst of the present invention. Further, it is particularly preferable that the component is not substantially contained.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "part" means "part by mass" and "%" means "% by mass".
In addition, COD means 1,5-cyclooctadiene.

In the following examples and comparative examples, analysis and evaluation were performed as follows.
<Measurement method by MALDI-TOF MS (matrix-assisted laser desorption / ionization time-of-flight mass spectrometry)>
The sample and matrix (dislanol) were each dissolved in THF (tetrahydrofuran) and mixed. The mixed solution was dropped onto a plate, dried, and measured using Bruker autoflex III (manufactured by Bruker).

<Inductively coupled plasma emission spectroscopic analysis (ICP-AES method)>
A sample (about 0.5 mg) was dispersed in concentrated nitric acid (1 ml) and heated at 105 ° C. for 3 hours. After the heating was completed, the mixture was allowed to cool to 40 ° C., and then 2 drops of hydrogen peroxide was added. After adding ultrapure water (2 ml), the carbon material was removed by filtration to obtain a measurement sample solution containing a metal. The S sample solution was made up to 25 mL, and the iron content was evaluated by a calibration curve method using SHIMADZU ICPS-8100 (manufactured by Shimadzu Corporation). The measurement was performed 3 times for each sample, and the average value was shown as the mass concentration of iron.

<Elemental analysis method>
The mass concentration of CHN was measured using a vario EL cube CHNS (manufactured by elementer).
<Thermogravimetric analysis>
Using ThemoPlusEVOII (manufactured by Rigaku Co., Ltd.), the temperature was raised to 10 ° C./min under a nitrogen stream.
<X-ray photoelectron spectroscopy>
The procedure was performed using SHIMADZU KRAROSAXIS-165x (manufactured by Shimadzu Corporation) under the conditions of an X-ray source Mg-Kα and a path energy of 40 kV.

<Structural analysis method near the X-ray absorption edge (XANES method)>
Since the metal content was about 1-5 wt% and all except the metal component were light elements of CHNO, pellets whose thickness was calculated were prepared and measured by a normal permeation method under room temperature atmosphere. The measurement data was XFS data near the Fe-K absorption edge (pre-edge peak intensity, absorption edge position, White Line intensity, EXAFS vibration, measurement range: 6800 to 8200 eV. SAGA-LS BL12 was used for measurement.

<Wide area X-ray absorption fine structure analysis method (EXAFS method)>
Since the metal content was about 1-5 wt% and all except the metal component were light elements of CHNO, pellets whose thickness was calculated were prepared and measured by a normal permeation method under room temperature atmosphere. The measurement data was measured with XFS data (EXAFS vibration, measurement range: 6800 to 8200 eV. SAGA-LS BL12 near the Fe-K absorption end.

<Measurement of oxygen reduction reaction activity>
After stirring and mixing the carbon catalyst (4 mg) and the 5 wt% Nafion (registered trademark) solution (100 μl), sonication was performed in an ice bath for 30 minutes to obtain a carbon catalyst dispersion. Glassy carbon (diameter 5.0 mm) and platinum ring holder (Pt purity 99.99%, ID 6.5 mm, OD 7.5 mm) were used for the rotating ring disk electrode. A carbon catalyst dispersion (10 μl) was slowly dropped onto the polished disk electrode, combined with a container containing a Nafion solution, covered with a glass container, and allowed to stand to dry. The catalyst-supported electrode prepared above was used as the working electrode, the platinum mesh was used as the counter electrode, and the silver chloride electrode (+0.199V vs NHE) was used as the reference electrode. Using a rotating ring disk electrode (RRDE), measurements were taken under the conditions of oxygen saturated HClO ₄ solution (pH 1), 25 ° C., electrode rotation speed 2000 rpm, recovery efficiency 26%, and ring electrode potential _Ering = 1.2 V. The measurement was performed by sweeping the potential of the disk electrode in an oxygen-saturated electrolytic solution at a potential range of 1.0 to 0.0 V (vs RHE) from negative to positive at a rate of 5 mV / s. The measurement result background under nitrogen saturation conditions was used.

(Manufacturing Examples 1 to 3)
According to the following reaction formula, PPyTP (X = H) which is a nitrogen-containing polycyclic compound (monomer) of Example 1, [PPyTP] _n which is a nitrogen-containing polycyclic compound (polymer) of Example 2, and Example 3 BPy-GNR, which is a nitrogen-containing polycyclic compound (nitrogen-containing GNR), was synthesized.

The reaction for obtaining [PPyTP] _n , which is a nitrogen-containing polycyclic compound (polymer) of Example 2, will be described in detail below.

To a two-necked flask, add Ni (COD) ₂ (304 mg, 0.90 mmol), 2,2'-bipyridyl (140 mg, 0.90 mmol), COD (160 μL, 0.9 mmol), and degassed DMF (5 mL). The reaction was carried out by stirring at 55 ° C. for 30 minutes.
This reaction solution is added dropwise to a mixture of a bromo compound (160 mg, 0.23 mmol) of the nitrogen-containing polycyclic compound of the present invention and degassed toluene (5 mL) in a Schlenk flask, and the mixture is heated at 80 ° C. for 2 days. Stirred.
Precipitated in methanol, filtered and washed with methanol, concentrated hydrochloric acid, water, methanol solution of sodium hydroxide (0.5 M), methanol and acetone to give a yellow powder ([PPyTP] _n , 110 mg).

An armchair-type BPy-GNR (hereinafter, also simply referred to as BPy-GNR), which is a nitrogen-containing polycyclic compound (nitrogen-containing GNR) of Example 3, was obtained by a reaction represented by the following reaction formula.

[PPyTP] _n (500 mg), dichloromethane (250 mL), and FeCl ₃ (2.5 g) in nitromethane were added dropwise to the Schlenk flask, and the mixture was stirred for 24 hours while bubbling nitrogen. The reaction mixture was filtered and washed with methanol, concentrated hydrochloric acid, water, a methanol solution of sodium hydroxide (0.5 M), methanol and acetone to obtain a brown powder (BPy-GNR, 400 mg).

(Baking)
PPyTP, [PPyTP] _n , BPy-GNR (0.1 mmol each) in ethyl acetate, FeCl _{2.4H 2 O} (0.1 mmol) in methanol, and Vulcan XC-72R (manufactured by Cabot), which is a carbon material. , 33.3 mg) in an electric furnace under a nitrogen stream, heated to 300 ° C. in 1 hour, held at 300 ° C. for 2 hours, further heated to 1000 ° C. in 1 hour, and then 1000 ° C. for 2 hours. It was fired in. Then, it was washed with 0.5M sulfuric acid at 80 ° C. for 3 hours, washed with deionized water, and dried. The obtained fired body is also referred to as Fe / PPyTP @ VC (Example 4), Fe / [PPyTP] _n @ VC (Example 5), and Fe / BPy-GNR @ VC (Example 6), respectively.

(Identification)
FIG. 1 shows the results of measuring MALDI-TOFMS for [PPyTP] _n and BPy-GNR. FIG. 2 shows inductively coupled plasma emission spectroscopy (ICP-AES) for [PPyTP] _n , BPy-GNR, Fe / PPyTP @ VC, Fe / [PPyTP] _n @ VC, Fe / BPy-GNR @ VC, respectively. The result of measuring the elemental analysis is shown. FIG. 3 shows the results of thermogravimetric measurement of PPyTP, [PPyTP] _n , and BPy-GNR. In addition, the synthesis of each compound was confirmed by ¹ H-NMR and ¹³ C-NMR.

(Confirmation of Fe-N bond between pyridine-type nitrogen and iron)
FIG. 4 shows the results of X-ray photoelectron spectroscopy performed on BPy-GNR and BPy-GNR with iron ions added. In the case where iron ions were added, a peak derived from the Fe—N bond between pyridine-type nitrogen and iron was confirmed at a binding energy of 400.2 eV.
FIG. 5 shows the results of X-ray photoelectron spectroscopy performed on Fe / PPyTP @ VC, Fe / [PPyTP] _n @ VC, and Fe / BPy-GNR @ VC. Peaks derived from the Fe—N bond at a binding energy of 400.2 eV were confirmed to be 11.8%, 35.7%, and 40.7%, respectively, and it was confirmed that iron was coordinated with pyridine-type nitrogen.

6 and 7 show the results of analysis of the X-ray absorption fine structure for Fe / PPyTP @ VC, Fe / [PPyTP] _n @ VC, and Fe / BPy-GNR @ VC. For these fired bodies, peaks derived from the Fe—N bond could be observed. In FIG. 6, FeTPP represents a porphyrin iron complex having an Fe—N bond.

(Oxygen reduction reaction activity)
FIG. 8 shows the oxygen reduction reaction activity for Fe / PPyTP @ VC, Fe / [PPyTP] _n @ VC, and Fe / BPy-GNR @ VC. The respective _Eonset showed high values of 0.87V, 0.88V, and 0.86V. It is considered that such a calcined body can sufficiently reduce the activation energy required for oxygen reduction. In FIG. 8, n = 4.0 indicates that the number of reducing electrons is four.

FIG. 9 shows Fe / PPyTP @ VC of Example 4, Fe / 1 @ VC (Comparative Example 1), Fe / 2 @ VC (Comparative Example 2), and Fe / 3 @ VC (Comparative Example 3), which are comparative examples. ) Shows the oxygen reduction reaction activity. Fe / 1 @ VC, Fe / 2 @ VC, and Fe / 3 @ VC are each obtained by supporting the compound shown in FIG. 9 with iron and firing it by the same method as in this example. It was found that the fired body of the example exhibited extremely excellent oxygen reduction reaction activity because the position and number of nitrogen atoms in the constituent units constituting the graphene nanoribbon as a raw material were specified.

Claims (3)

A nitrogen-containing polycyclic compound having a structural unit containing a structure represented by the following general formula (1).

(In the formula, X ¹ and X ² are each a halogen atom, an OTf group, an OTs group, or a structure other than the structure represented by the general formula (1) in the structural unit or another structural unit. Tf represents a trifluoromethylsulfonyl group, Ts represents a tosyl group, and Y1, Y2, ^Y7 , and ^{Y8 are} carbon atoms bonded to ^a hydrogen atom, respectively. Alternatively, it represents a carbon atom bonded to a structure other than the structure represented by the general formula (1) or another structural unit in the structural unit. Y ³ and Y ⁴ , Y ⁵ and Y ⁶ are respectively. One represents a nitrogen atom and the other represents a carbon atom bonded to a hydrogen atom. A dotted line indicates that a bond may or may not be formed.) The fired body of the nitrogen-containing polycyclic compound according to claim 1 . An oxygen reduction catalyst comprising the nitrogen-containing polycyclic compound according to claim 1 or the calcined product according to claim 2 .

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