JP6287344B2 - Method for producing carbon nitride film - Google Patents

Description

  The present invention relates to a carbon nitride precursor composition, a method for producing carbon nitride, and an electrode material.

  Since carbon nitride is excellent in hardness, electrical conductivity, thermal conductivity, corrosion resistance and the like, it is considered useful as an electrical element material including a power device. In particular, porous carbon nitride is expected to be applied to various uses such as carriers, adsorbents, and electrode materials.

  As a method for producing carbon nitride, a thermal decomposition method, a beam evaporation method, a high-pressure shock wave synthesis method, a laser ablation method, a molten salt electrolysis method, and the like are known (see, for example, Patent Documents 1 and 2). In addition, a method is known in which an oligomer or a polymer of a first compound serving as a carbon source and a second compound serving as a nitrogen source is baked in an inert atmosphere (see, for example, Patent Documents 3 and 4). ).

JP 2009-120861 A JP-A-9-227298 JP-A-2-206619 International Publication WO2008 / 126799 Thermal decomposition method, beam evaporation method, high-pressure shock wave synthesis method, laser ablation method, and molten salt electrolysis method each have problems in terms of production efficiency, cost, or energy consumption. On the other hand, the methods described in Patent Documents 3 and 4 have partially solved the above problems, but are not sufficient in terms of carbonization yield.

  The present invention provides a carbon nitride precursor composition that is excellent in terms of production efficiency, cost, and energy consumption, and that provides a high carbonization yield, and a method for producing carbon nitride. The carbon nitride obtained by the present invention is suitable for an electrode material, for example.

  The carbon nitride precursor composition according to the present invention includes a polymer of a compound represented by the following formula (1) and a solvent.

(Ar represents an aromatic hydrocarbon group having 6 to 18 carbon atoms or a group in which a part of carbon on the aromatic ring is substituted with a nitrogen atom. The hydrogen atom on the aromatic hydrocarbon group is a part or All may be substituted by a halogen atom, an amino group, a cyano group, an aliphatic hydrocarbon group having 1 to 8 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms, and P ¹ represents a polymerizable group. P ² represents a hydrogen atom or an organic group having a carbon-carbon unsaturated bond which forms a conjugated system together with the carbon-nitrogen double bond in the above formula, R ¹ is a hydrogen atom, a C 1-8 fat. Represents an aromatic hydrocarbon group or an aromatic hydrocarbon group having 6 to 10 carbon atoms, and m represents 0 or an integer of 1 or more.)
The method for producing carbon nitride according to the present invention includes a step of applying a composition containing a polymer of a compound represented by the following formula (1) and a solvent on a support,

(Ar represents an aromatic hydrocarbon group having 6 to 18 carbon atoms or a group in which a part of carbon on the aromatic ring is substituted with a nitrogen atom. The hydrogen atom on the aromatic hydrocarbon group is a part or All may be substituted by a halogen atom, an amino group, a cyano group, an aliphatic hydrocarbon group having 1 to 8 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms, and P ¹ represents a polymerizable group. P ² represents a hydrogen atom or an organic group having a carbon-carbon unsaturated bond which forms a conjugated system together with the carbon-nitrogen double bond in the above formula, R ¹ is a hydrogen atom, a C 1-8 fat. Represents an aromatic hydrocarbon group or an aromatic hydrocarbon group having 6 to 10 carbon atoms, and m represents 0 or an integer of 1 or more.)
Heating the support coated with the composition in an inert gas;
Is provided.

  The electrode material according to the present invention is obtained using the carbon nitride precursor composition according to the present invention as a raw material.

  The carbon nitride precursor composition and the method for producing carbon nitride according to the present invention are excellent in terms of production efficiency, cost, and energy consumption, and give a high carbonization yield.

<Carbon nitride precursor composition>
The carbon nitride precursor composition according to the present invention contains a polymer of a compound represented by the following formula (1) and a solvent.

(Ar represents an aromatic hydrocarbon group having 6 to 18 carbon atoms or a group in which a part of carbon on the aromatic ring is substituted with a nitrogen atom. The hydrogen atom on the aromatic hydrocarbon group is a part or All may be substituted by a halogen atom, an amino group, a cyano group, an aliphatic hydrocarbon group having 1 to 8 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms, and P ¹ represents a polymerizable group. P ² represents a hydrogen atom or an organic group having a carbon-carbon unsaturated bond which forms a conjugated system together with the carbon-nitrogen double bond in the above formula, R ¹ is a hydrogen atom, a C 1-8 fat. Represents an aromatic hydrocarbon group or an aromatic hydrocarbon group having 6 to 10 carbon atoms, and m represents 0 or an integer of 1 or more.)
The compound represented by formula (1) is an aromatic ring Ar, carbon - nitrogen double bond and an organic group P ² form a conjugated system. The conjugated system maintains a carbon-nitrogen atom network and contributes to an improvement in carbonization yield. Examples of the aromatic hydrocarbon group Ar include an aromatic hydrocarbon group such as a benzene ring, a naphthalene ring, an anthracene ring or a pyrene ring, or a pyridine ring in which a part of carbon atoms constituting the aromatic ring is substituted with a nitrogen atom And nitrogen-containing aromatic hydrocarbon groups such as a triazine ring.

  The compound represented by formula (1) is preferably used after polymerization. By polymerizing the compound, the coating film can be easily formed, and a uniform carbon nitride film can be easily formed. Moreover, volatilization of a compound and its decomposition product is suppressed and it contributes to the further improvement of a carbonization yield.

Polymerization of the compound represented by the formula (1) can be carried out using a carbon-nitrogen unsaturated bond or a carbon-carbon unsaturated bond of the organic group P ² as a reaction point, but the polymerizable group P ¹ is reacted. It is preferable to carry out as a point. By carrying out the polymerization using the polymerizable group P ¹ as a reaction point, a conjugated system containing an unsaturated bond between carbon and nitrogen is maintained even after the polymerization, which contributes to further improvement of the carbonization yield. For this reason, in Formula (1), m is preferably 1 or more.
<Solvent>
The composition according to the present invention contains a solvent. A solvent that can dissolve the polymer of the compound represented by the formula (1) can be arbitrarily selected. Examples of the solvent that can be selected include alcohol solvents, ketone solvents, amide solvents, ether solvents, ester solvents, and the like. A solvent can be used individually by 1 type or in combination of 2 or more types. Examples of the alcohol solvent include methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, iso-butyl alcohol, sec-butyl alcohol, t-butyl alcohol, n-pentyl alcohol, iso- Monoalcohol solvents such as pentyl alcohol, sec-pentyl alcohol, t-pentyl alcohol; ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4 -Polyhydric alcohol solvents such as pentanediol, 2,5-hexanediol, and 2,4-heptanediol.

  Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, methyl-n-pentyl ketone, ethyl-n-butyl ketone, methyl- aliphatic ketone solvents such as n-hexyl ketone, di-iso-butyl ketone and trimethylnonanone; cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone and methylcyclohexanone; 2,4-pentane Examples include dione, acetonyl acetone, diacetone alcohol, acetophenone, methyl n-amyl ketone, and the like.

  Examples of the amide solvent include cyclic amide solvents such as 1,3-dimethyl-2-imidazolidinone and N-methyl-2-pyrrolidone; formamide, N-methylformamide, N, N-dimethylformamide, N , N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropionamide and other chain amide solvents.

  Examples of the ether solvent include polyhydric alcohol partial ether solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol dimethyl ether; ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether Polyhydric alcohol partial ether acetate solvents such as acetate (PGMEA) and propylene glycol monoethyl ether acetate; Dialiphatic ethers such as diethyl ether, dipropyl ether, dibutyl ether, butyl methyl ether, butyl ethyl ether, diisoamyl ether Solvent; aliphatic-aromatic ether solvent such as anisole and phenylethyl ether; tetrahydride Furan, tetrahydropyran, and cyclic ether solvents dioxane.

Examples of the ester solvent include methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec-butyl acetate, and n-pentyl acetate. Sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, n-nonyl acetate, methyl acetoacetate, ethyl acetoacetate, etc. Examples thereof include carboxylic acid ester solvents; lactone solvents such as γ-butyrolactone and γ-valerolactone; and carbonate ester solvents such as diethyl carbonate and propylene carbonate.
<Compound>
The manufacturing method of the compound represented by Formula (1) is not limited. For example, a compound represented by the formula (1) can be obtained by reacting an aromatic compound having an amino group with a β-unsaturated aldehyde. Specific examples include reactions represented by the following formula. In the following formula, TFA represents trifluoroacetic acid.

  By applying the same technique to the combination of a nitrogen-containing compound and an aldehyde, various carbon nitride precursor compositions can be obtained. Examples of such combinations are shown below.

Many of the compounds represented by formula (1) react easily by heating to give oligomers or polymers. If necessary, a radical generator such as an azo compound or an organic peroxide may be used in combination as a polymerization initiator. The molecular weight of the oligomer or polymer is not limited. For example, an oligomer or polymer having a number average molecular weight of about 400 to 10,000 and a weight average molecular weight of about 500 to 30,000 measured by gel permeation chromatography is used as a carbon nitride precursor composition. It can be used for things.
<Other optional components>
The carbon nitride precursor composition according to the present invention can further contain other components. Examples of other components include surfactants, viscosity modifiers, porogens, and adhesion aids. As used herein, porogen refers to an additive that is dispersed in a carbon nitride precursor composition and that forms pores by decomposition or volatilization during firing. Porous carbon nitride is obtained by blending and dispersing the porogen.
[Surfactant]
The surfactant improves the coating property of the carbon nitride precursor composition. As a result, the uniformity of the formed film is improved and the occurrence of coating spots is suppressed. Surfactant can be used individually by 1 type or in combination of 2 or more types.

  Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene-n-octylphenyl ether, polyoxyethylene-n-nonylphenyl ether, polyethylene glycol dilaurate, Nonionic surfactants such as polyethylene glycol distearate are listed. Commercially available products include KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (manufactured by Kyoeisha Yushi Chemical Co., Ltd.), Ftop EF101, EF204, EF303, EF352 (manufactured by Tochem Products), MegaFuck F171, F172, F173 (manufactured by Dainippon Ink and Chemicals, Inc.) ), FLORARD FC430, FC431, FC135, FC93 (above, manufactured by Sumitomo 3M), Asahi Guard AG710, Surflon S382, SC101, SC102, SC103, SC104, SC105, SC106 (above, manufactured by Asahi Glass) ) And the like.

The compounding amount of the surfactant is preferably more than 0 parts by mass and 10 parts by mass or less, more preferably 0.001 parts by mass to 5 parts by mass, and more preferably 0.005 parts by mass to 100 parts by mass of the compound represented by the formula (1). 1 part by mass or less is more preferable. By making the compounding quantity of surfactant into the said range, the applicability | paintability of the carbon nitride precursor composition composition concerning this invention can further be improved.
[Adhesion aid]
The adhesion assistant improves the adhesion with the support. As a result, the adhesion between the carbon nitride film and the support can be improved. The adhesion assistant can be used singly or in combination of two or more.

  The blending amount of the adhesion assistant is preferably more than 0 parts by mass and less than 10 parts by mass, more preferably 0.01 parts by mass to 10 parts by mass, and more preferably 0.01 parts by mass to 100 parts by mass of the compound represented by the formula (1). 5 parts by mass is more preferable.

The carbon nitride precursor composition according to the present invention can be prepared by mixing a polymer of the compound represented by the formula (1), a solvent, and the other components described above. The solid content concentration of the composition is preferably 0.1% by mass to 50% by mass, more preferably 1% by mass to 30% by mass, further preferably 3% by mass to 20% by mass, and particularly preferably 5% by mass to 15% by mass. preferable.
<Method for producing carbon nitride and method for forming carbon nitride film>
The method for producing carbon nitride according to the present invention includes a step of heating a composition containing a polymer of the compound represented by formula (1) and a solvent under an inert atmosphere. The inert gas is preferably nitrogen. When forming a carbon nitride film, the composition is applied to the support surface, and the solvent is removed to form a coating film. A carbon nitride film is obtained by heating the formed coating film in an inert atmosphere.

  Hereinafter, the present invention will be described more specifically with reference to examples. This example does not limit the technical scope of the present invention.

Diaminomaleonitrile (DAMN) (Alpha Aesar, purity 98%), 3-ethynylaniline (Alpha Aesar), acrolein (Aldrich, purity 95%), trifluoroacetic acid (TFA) (Aldrich) ), Pluronic (registered trademark) P123 ((C ₂ H ₄ O) ₂₀ (C ₃ H ₆ O) ₇₀ (C ₂ H ₄ O) ₂₀ , manufactured by BASF), dimethylformamide (DMF) (manufactured by Aldrich), Dimethyl sulfoxide (DMSO) and tetrahydrofuran (THF) were used without purifying commercially available products, and a P-type silicon (100) substrate (available through Active Business Company GmbH) was used as the silicon substrate Acrodam (chemical name: (1Z ) -1-Amino-1,2-dicyano-3-aza-1,3,5-hexatriene)) Was synthesized by the method described in known literature (DM Johnson et al, Macromolecules 2005, 38, 3615). The structure of the obtained Acrodam was confirmed by analysis to be the same as previously reported. Polyacrodames (referred to herein as acrodamum oligomers) were obtained by substituting THF for diethyl ether in the previously reported method.
(Synthesis Example 1)
DAMN (5.41 g, 50 mmol) and THF (60 mL) were placed in a 250 mL round bottom flask, and stirring was started using a magnetic stirrer. After the mixture was cooled in a cold bath for 15 minutes, acrolein (4.0 mL, 55 mmol) was added. The mixture was again cooled in the cold bath for 15 minutes before TFA (0.06 g) was added. After adding TFA, the mixture was stirred for 30 minutes until the reaction mixture became homogeneous. The reaction solution was distilled off under reduced pressure to obtain a solid. The obtained solid was pulverized in a mortar. As a result of drying the pulverized solid at 60 ° C. under reduced pressure, polyacrodames were quantitatively obtained. The obtained polyacrodames were soluble in THF, DMF and DMSO. As a result of molecular weight measurement by gel permeation chromatography (eluent: DMSO, calibration curve method, standard substance: polymethyl methacrylate (PMMA) having a known molecular weight), the number average molecular weight was 2500 and the weight average molecular weight was 5000.
(Reference Example 1)
Polyacrodam (0.10 g), Pluronic (registered trademark) P123 (1 mg), DMF (0.45 g) and THF (0.45 g) were mixed in a glass bottle to obtain a coating solution for spin coating. A silicon substrate (3 × 3 cm) was set on the spinner. While rotating the silicon substrate, a sufficient amount of THF was poured and washed. After confirming that the coating solution was a uniform solution, a part thereof was poured onto a cleaned silicon substrate. The silicon substrate was rotated at 1200 rpm for 15 seconds and then placed on a heating plate at 200 ° C. for 1 minute. The silicon substrate was cooled to room temperature and then placed in a ceramic container. Under a nitrogen stream, the temperature was raised at a rate of 100 ° C./hour until the temperature reached 800 ° C. and then calcined at 800 ° C. for 1 hour. A silicon substrate having a smooth film on the surface was obtained. When the surface was analyzed by infrared absorption spectrum (IR), peaks near 3400 cm ⁻¹ derived from carbon-hydrogen and nitrogen-hydrogen bonds decreased, and 1220 cm ⁻ derived from carbon-nitrogen sp ³ bonds. ^Since the peak of ¹ increased, it was confirmed that a carbon nitride film was formed. Restricted field electron diffraction (SAED) and Raman spectral analysis suggested that the carbon nitride film was amorphous. When the cross section was observed with a scanning electron microscope (SEM), the thickness of the carbon nitride film was about 720 nm. The sheet resistance value was 230 ohms / sq. The mass of the film was about 60% before calcination.
Example 1
3-Ethynylaniline (1.17 g, 10 mmol) and THF (10 mL) were placed in a 250 mL round bottom flask, and stirring was started using a magnetic stirrer. After the mixture was cooled in a cold bath for 15 minutes, acrolein (0.8 mL, 11 mmol) was added. The mixture was again cooled in the cold bath for 15 minutes before TFA (0.01 g) was added. After adding TFA, the mixture was stirred for 30 minutes until the reaction mixture became homogeneous. The reaction was warmed to about 25 ° C. and then heated to reflux for 24 hours. The reaction solution was distilled off under reduced pressure to obtain a solid. The obtained solid was pulverized in a mortar. As a result of drying the pulverized solid at 60 ° C. under reduced pressure, oligomer 1 was quantitatively obtained.
(Example 2)
Oligomer 1 (0.10 g), Pluronic (registered trademark) P123 (1 mg), DMF (0.45 g), and THF (0.45 g) were mixed in a glass bottle to obtain a coating solution for spin coating. A silicon substrate (3 × 3 cm) was set on the spinner. While rotating the silicon substrate, a sufficient amount of THF was poured and washed. After confirming that the coating solution was a uniform solution, a part thereof was poured onto a cleaned silicon substrate. The silicon substrate was rotated at 1200 rpm for 15 seconds and then placed on a heating plate at 200 ° C. for 1 minute. The silicon substrate was cooled to room temperature and then placed in a ceramic container. Under a nitrogen stream, the temperature was raised at a rate of 100 ° C./hour until the temperature reached 800 ° C., and then calcined at 800 ° C. for 1 hour. A silicon substrate having a carbon nitride film on the surface was obtained. The mass of the film was about 65% before calcination.

(Reference Example 2)
A silicon substrate provided with a carbon nitride film on the surface was obtained in the same procedure as in Example 2, except that the compound described in the following formula was used as a raw material at 2/1/1 (molar ratio basis). The obtained carbon nitride film had a resistance value of about 2 kohms.

(Example 3)
A silicon substrate having a carbon nitride film on the surface was obtained in the same procedure as in Example 2 except that the compound described in the following formula was used as a raw material at 2/3/2 (molar ratio basis). The obtained carbon nitride film had a resistance value of about 4 kohms.

Claims (3)

Heating the compound represented by the following formula (1) in the presence or absence of a radical generator to obtain a polymer;
Applying a composition comprising the polymer and a solvent on a support;
Heating the support coated with the composition in an inert gas;
A method for producing a carbon nitride film comprising:
(In the formula (1), Ar represents an aromatic hydrocarbon group having 6 to 18 carbon atoms or a group in which part of carbon on the aromatic ring is substituted with a nitrogen atom. Hydrogen on the aromatic hydrocarbon group. A part or all of the atoms may be substituted with a halogen atom, an amino group, a cyano group, an aliphatic hydrocarbon group having 1 to 8 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms. ¹ Represents a polymerizable group. P ² Represents an organic group having a hydrogen atom or a carbon-carbon unsaturated bond forming a conjugated system together with the carbon-nitrogen double bond in the above formula (1). R ¹ Represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 8 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms. m represents 0 or an integer of 1 or more. ) P ¹ The method for producing a carbon nitride film according to claim 1, wherein is an ethenyl group or an ethynyl group, and m is an integer of 1 or more. The method for producing a carbon nitride film according to claim 1, wherein the composition further contains a porogen, and the obtained carbon nitride film is a porous carbon nitride film.